100 Orthopedic MCQs: Basic Science, Oncology, Trauma & Spine | Comprehensive ABOS Review

Joshi and associates reported a 96% incidence of pain relief in 181 total hip arthroplasties in patients with ankylosing spondylitis. Only 65% of patients had good to excellent functional results, primarily the result of associated systemic diseases and spinal deformity. The incidence of infection was slightly higher, and the incidence of heterotopic ossification was higher in this group of patients.

Ginkgo biloba is a popular nutraceutical for patients who have early dementia, intermittent claudication secondary to peripheral vascular disease, vertigo, and tinnitus. It is reported to improve mental alertness and cognitive deficiency. It has antiplatelet properties as a result of one of its components, ginkgolide B, which displaces platelet-activating factor from its receptor binding sight. Rowin and Lewis reported on spontaneous bilateral subdural hematomas associated with chronic ginkgo biloba ingestion. Vale also reported on subarachnoid hemorrhage associated with ginkgo biloba. Bebbington and associates reported on persistent postoperative bleeding after total hip arthroplasty secondary to ginkgo biloba usage. Furthermore, the use of ginkgo biloba with aspirin or other antiplatelet agents or anticoagulants represents a relative contraindication. Physicians should be aware not only of prescribed medications but also alternative nutraceuticals that are used by the patient. Rowin J, Lewis SL: Spontaneous bilateral subdural hematomas associated with chronic ginkgo biloba ingestion. Neurology 1996;46:1775-1776. Vale S: Subarachnoid hemorrhage associated with ginkgo biloba. Lancet 1998;352:36.

The subtrochanteric femur has been identified as an anatomic site that is particularly prone to pathologic fracture. An avulsion fracture of the lesser trochanter is a sign of impending femoral fracture. While the other anatomic locations are also frequently involved in metastatic bone disease, pathologic fractures occur less commonly. Simon MA, Springfield DS, et al: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, p 683.

Two recent studies by Pollak and associates and Marsh and associates have focused on function after high-energy tibial plafond fractures. Findings are unfavorable even when anatomic reduction is performed in the best centers and patients are provided excellent rehabilitation. Function improves up to 2 years after injury, but even basic walking skills remain adversely affected. Virtually all patients have long-term adverse general health effects compared to their gender and age-matched peers. Posttraumatic degenerative arthritis is present in most ankles. Patients should be told early about the long-term prognosis, and early vocational/psychological counseling should be given. Despite these adverse outcomes, only a minority of patients require fusion or arthroplasty. Pollak AN, McCarthy ML, Bess RS, et al: Outcomes after treatment of high-energy tibial plafond fractures. J Bone Joint Surg Am 2003;85:1893-1900.

The radiographs show posterior flexion instability that is the result of a flexion-extension gap imbalance and posterior cruciate ligament incompetence after a posterior cruciate ligament-retaining TKA. The femur is anteriorly displaced on the tibia, with lift-off of the femoral component from the tibial polyethylene. Revision to a larger femoral component will address the larger flexion gap relative to the extension gap, and a posterior stabilized implant will address the posterior cruciate ligament insufficiency. Pagnano and associates, reporting on a series of painful TKAs previously diagnosed as pain of unknown etiology, showed that the pain was secondary to flexion instability. Pain relief was achieved by revision to a posterior stabilized implant. Pagnano MW, Hanssen AD, Lewallen DG, et al: Flexion instability after primary posterior cruciate retaining total knee arthroplasty. Clin Orthop 1998;356:39-46. Fehring TK, Valadie AL: Knee instability after total knee arthroplasty. Clin Orthop 1994;299:157-162.

A positive lift-off test and increased passive external rotation are diagnostic of a subscapularis tear or detachment. Although a similar injury could produce anterior instability, this will test the integrity of the subscapularis. A locked dislocation has limited passive movement. A ruptured biceps tendon will most likely produce ecchymosis and findings similar to supraspinatus trauma. Internal impingement is not associated with subscapularis weakness. Gerber C, Krushell RJ: Isolated rupture of the tendon of the subscapularis muscle: Clinical features in 16 cases. J Bone Joint Surg Br 1991;73:389-394.

The patient has a calcaneonavicular tarsal coalition. Symptoms of calcaneonavicular coalitions typically are seen between the ages of 10 and 14 years. The cause of pain has not been clearly established. It has been postulated that the coalition stiffens with maturity and microfractures can result, producing pain. Resection of a calcaneonavicular coalition generally has been associated with a satisfactory result. Soft-tissue interposition, most commonly using the extensor digitorum brevis muscle, appears to be helpful. A hindfoot arthrodesis (usually triple) would be reserved if coalition resection proves to be unsuccessful. Achilles tendon lengthening and orthotic support, as well as debridement of the sinus tarsi, are not expected to result in a satisfactory outcome. The patient does not have a flatfoot deformity. Vaccaro AR (ed): Orthopaedic Knowledge Update 8. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2005, pp 757-765.

Most children with amyoplasia are ambulatory and when a decrease in function occurs because of a severe contracture, it must be addressed. A radical posterior soft-tissue release, including the posterior knee capsule and often the collateral ligaments and the posterior cruciate ligament, is needed to obtain extension. After the age of 1 year, aggressive physical therapy will do little to correct a contracture. Botulinum toxin A is indicated for spasticity and is contraindicated with severe contractures. Supracondylar femoral extension osteotomy works well, but will remodel at an average rate of 1 degree per month, which is not considered ideal in a young patient. Gradual correction with a circular ring external fixator is an option, but a soft-tissue release will also most likely be needed for a contracture of this severity. Sarwark JF, MacEwen GD, Scott CI Jr: Amyoplasia (a common form of arthrogryposis). J Bone Joint Surg Am 1990;72:465-469. DelBello DA, Watts HG: Distal femoral extension osteotomy for knee flexion contracture in patients with arthrogryposis. J Pediatr Orthop 1996;16:122-126.

Severely displaced acromioclavicular injuries disrupt the deltotrapezial fascia and muscular origin in addition to the ligaments (acromioclavicular and coracoclavicular or trapezoid and conoid). When the deltoid is still attached to the clavicle, an isometric shoulder shrug will tend to reduce the displacement. When the deltoid is detached but the trapezius is attached, this manuever will increase the deformity and surgery may be indicated.

Flexor digitorum profundus ruptures are classified into three types. In type I, the tendon retracts into the palm. In type II, the tendon retracts to the level of the proximal phalanx, the vinculum remains intact, and the blood supply is preserved to the tendon. A small fleck of bony fragment observed at the A2 pulley is pathognomonic for a type II rupture. Successful primary repair of the type II rupture has been reported as late as 2 months after the injury. Type III injuries have large fragments of the distal phalanx attached and are caught distally by the A1 pulley. Type III ruptures can be repaired up to several months after the injury. Leddy JP: Avulsions of the flexor digitorum profundus. Hand Clin 1985;1:77-83.

The patient has a displaced femoral neck fracture. Although the treatment remains controversial, most clinicians advocate either a closed or open reduction in younger active patients. Achieving an anatomic reduction is necessary to avoid loss of reduction, nonunion, or osteonecrosis. An acceptable reduction may have up to 15 degrees of valgus angulation and 10 degrees of posterior angulation. Parallel multiple screws or pins are the most common method of internal fixation. Prosthetic replacement is generally reserved for older and less active individuals. Callaghan JJ, Dennis DA, Paprosky WG, et al (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1995, pp 97-108.

The PCBMN originates from the median nerve proper between 3 and 21 cm proximal to the wrist with moderate variation. It virtually always originates from the radial side of the nerve and travels distally with the median nerve, radial to the palmaris longus, and ulnar to the flexor carpi radialis. Hobbs RA, Magnussen PA, Tonkin MA: Palmar cutaneous branch of the median nerve. J Hand Surg Am 1990;15:38-43.

Paletta and Laskins performed a retrospective study of the results of TKA with cement in 22 patients who had a previous patellectomy. Nine of the patients had insertion of a posterior cruciate ligament-substituting implant. Thirteen patients had insertion of a posterior cruciate ligament-sparing implant. The 5-year postoperative knee scores were 89 for the posterior cruciate ligament-substituting knee versus 67 for the posterior cruciate ligament-sparing knee (P < 0.01). The patella functions to increase the lever arm of the extensor mechanism and to position the quadriceps tendon and the patellar ligament roughly parallel to the anterior cruciate ligament and posterior cruciate ligament, respectively. The patellar ligament thereby provides a strong reinforcing structure that functions to prevent excessive anterior translation of the femur during flexion of the knee. The absence of the patella results in the patellar ligament and the quadriceps tendon being relatively in line with one another. After a patellectomy, the resultant quadriceps force is no longer parallel to the posterior cruciate ligament. This results in loss of the reinforcing function of the patellar ligament. The authors believe this loss of reinforcing function may place increased stresses on the posterior cruciate ligament and posterior aspect of the capsule, which may result in stretching of these structures over time. They found a high rate of anteroposterior instability, a high prevalence of recurvatum, and a high rate of loss of full active extension compared with passive extension in the posterior cruciate ligament-sparing group, which supports their theory. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 559-582.

Endoscopic ACL reconstructive techniques may result in a vertical graft placement. The reconstructed ligament will resist anterior translation of the tibia but the graft will not restore rotatory stability. Decreased flexion and extension are caused by placement of the femoral tunnel too anterior and posterior, respectively. Impingement of the graft on the femoral notch is caused by anterior placement of the tibial tunnel or inadequate notchplasty. Scopp JM, Jasper LE, Belkoff SM, et al: The effect of oblique femoral tunnel placement on rotational constraint of the knee reconstructed using patellar tendon autografts. Arthroscopy 2004;20:294-299.

The patient has an axillary nerve injury, which is relatively uncommon after surgery for instability. This type of injury generally is the result of a stretch injury rather than transection or a hematoma. Therefore, observation is indicated in the early postoperative period. After approximately 6 weeks, electromyography can be used to confirm and document the point of injury. Interscalene blocks can cause prolonged nerve injury but usually are not limited to the axillary nerve.

Retrograde ejaculation is a sequela of injury to the superior hypogastric plexus. The structure needs protection, especially during anterior exposure of the lumbosacral junction. The use of monopolar electrocautery should be avoided in this region. The ideal exposure starts with blunt dissection just to the medial aspect of the left common iliac vein, sweeping the prevertebral tissues toward the patient's right side. Although erectile dysfunction can be seen after spinal surgery, it is not typically related to the surgical exposure because erectile function is regulated by parasympathetic fibers derived from the second, third, and fourth sacral segments that are deep in the pelvis and are not at risk with the anterior approach. The other choices are complications of spinal surgery but are not uniquely associated with an anterior L5-S1 exposure. Flynn JC, Price CT: Sexual complications of anterior fusion of the lumbar spine. Spine 1984;9:489-492. Watkins RG (ed): Surgical Approaches to the Spine, ed 1. New York, NY, Springer-Verlag, 1983, p 107.

Flexor tenosynovitis of the thumb flexor tendon sheath can spread proximally and form an abscess within the thenar space of the palm. The flexor pollicis longus tendon does not pass through the central space of the palm or the hypothenar space of the palm. The flexor pollicis longus tendon does pass through the carpal tunnel, but this is not a palmar space. The three palmar spaces include the hypothenar space, the thenar space, and the central space. The posterior adductor space would likely only be involved secondarily after spread from a thenar space infection. Hollinshead W: Anatomy for Surgeons: The Back and Limbs, ed 3. Philadelphia, PA, Harper and Row, 1982, vol 3, pp 478-479.

Without more distal immobilization such as a thigh extension, the lower two lumbar segments generally show the same or even increased mobility with a TLSO. White AA, Panjabi MM: Clinical Biomechanics of the Spine, ed 2. Philadelphia, PA, JB Lippincott, 1990, pp 475-509.

The strongest biomechanical construct is posterior to anterior fixation with the entry point being at the level of the posterolateral tubercle of the talus. This uses the interval between the peroneus brevis and the flexor hallucis longus. The interval between the flexor digitorum longus and the flexor hallucis longus with entry at the posteromedial tubercle of the talus is not an accepted approach for fixation of talar neck fractures. All of the other options use screw placements from anterior to posterior. Swanson TV, Bray TJ, Homes GB Jr: Fractures of the talar neck: A mechanical study of fixation. J Bone Joint Surg Am 1992;74:544-551.

In two different biomechanical studies performed in both bovine and human cadaveric spines, all posterior techniques of stabilization were found to be superior to anterior plating in flexion-distraction injuries of the cervical spine. These injuries usually have an intact anterior longitudinal ligament that allows posterior fixation to function as a tension band. Anterior plating with grafting destroys this last remaining stabilizing structure and does not allow for a tension band effect because all of the posterior stabilizing structures have been destroyed with the injury. In clinical practice, however, anterior plating can be effective in the treatment of this injury with appropriate postoperative orthotic management. Sutterlin CE III, McAfee PC, Warden KE, et al: A biomechanical evaluation of cervical spine stabilization methods in a bovine model: Static and cyclical loading. Spine 1988;13:795-802.

The patient is at risk for a pelvic vascular injury and major hemorrhage. This type of complication of pelvic trauma is highest in motorcyclists. Once it is recognized that the pelvic ring has opened, it is important to close that ring to tamponade any venous bleeding with a pelvic binder and to add a skeletal traction pin to the limb on the involved side. This will correct any translational displacement. The noninvasive pelvic binders or sheets are easy to apply and are very effective. They do not compromise future care and allow the surgeons access to the abdomen. External fixation or pelvic resuscitation clamps require a certain amount of skill to apply and are not always available. If the pelvic stabilization does not improve the hemodynamic parameters in 10 to 15 minutes, angiography is necessary.

The patient has bilateral hypertrophic synovitis that is causing repeated hemarthroses and progressive arthropathy. Ankle synovectomy in patients with hemophilia is effective in significantly reducing the rate of joint bleeding and in slowing the progression of the arthropathy; therefore, bilateral synovectomies is the treatment of choice. Range of motion can be effectively maintained after ankle synovectomy. Bracing and prophylactic transfusions would be ineffective at this time. Ankle arthrodesis should be reserved for patients with severe pain. Compared with patients who have juvenile rheumatoid arthritis, patients with hemophilia generally do not have involvement of the subtalar joint and rarely require a pantalar arthrodesis. Greene WB: Synovectomy of the ankle for hemophilic arthropathy. J Bone Joint Surg Am 1994;76:812-819.

The incidence of injury associated with horseback rising is estimated to be one per 350 riding hours to one per 1,000 riding hours. Of these injuries, approximately 15% to 27% are severe enough to warrant hospital admission. Significant and serious injuries in equestrian activities are associated with recreational riders and those not wearing a helmet. Head and spine injuries are more common in recreational and nonhelmeted riders. Extremity injuries are more common in professional and helmeted riders. Professional riders are less likely to be admitted to the hospital than recreational riders, and are about half as likely to be disabled at 6 months after injury as recreational riders. Lim J, Puttaswamy V, Gizzi M, et al: Pattern of equestrian injuries presenting to a Sydney teaching hospital. ANZ J Surg 2003;73:567-571.

The supraspinatus tendon shows clear detachment and retraction from its greater tuberosity attachment by the absence of the normal dark subacromial signal extending to the attachment on the greater tuberosity. There is no anterior inferior glenoid labral detachment that usually is seen in a Bankart lesion. The acromioclavicular joint shows no evidence of separation. The humeral head is migrated cranially, indicating a chronic rotator cuff tear. Iannotti JP, Zlatkin MB, Esterhai JL, Kressel HY, Dalinka MK, Spindler KP: Magnetic resonance imaging of the shoulder: Sensitivity, specificity, and predictive value. J Bone Joint Surg Am 1991;73:17-29. Seeger LL, Gold RH, Bassett LW, Ellman H: Shoulder impingement syndrome: MR findings in 53 shoulders. Am J Roentgenol 1988;150:343-347.

Patients with a degenerative spondylolisthesis and severe stenosis who have failed appropriate nonsurgical management are candidates for surgical intervention. Most studies show good to excellent results in more than 85% of patients after lumbar decompression for stenosis. Atlas and associates found that at 8- to 10-year follow-up, leg pain relief and back-related functional status were greater in those patients opting for surgical treatment of the stenosis. Similarly, the decision to fuse a spondylolisthetic segment has been supported in the literature. Herkowitz and Kurz compared decompressive laminectomy alone and decompressive laminectomy with intertransverse arthrodesis in 50 patients with single-level spinal stenosis and degenerative spondylolisthesis. They demonstrated good to excellent results in 90% of the fused group compared to 44% in the nonfusion group. The decision to include instrumentation during the fusion is more controversial. Whereas the use of instrumentation has shown to improve fusion rates, it has not been conclusively shown to improve the overall clinical outcomes of patients. Atlas SJ, Keller RB, Wu YA, et al: Long-term outcomes of surgical and nonsurgical management of lumbar spinal stenosis: 8 to 10 year results from the Maine lumbar spine study. Spine 2005;30:936-943. Herkowitz HN, Kurz LT: Degenerative lumbar spondylolisthesis with spinal stenosis: A prospective study comparing decompression with decompression and intratransverse process arthrodesis. J Bone Joint Surg Am 1991;73:802-808.

Radiation-associated sarcomas typically occur at least 5 years following radiation therapy, in the radiation therapy field, and with different histology than the original disease. The radiograph shows a lytic destructive lesion of the medial clavicle. The radiographic differential could include any of the above etiologies. The CT and MRI scans show this same reaction with extension into the adjacent soft tissue and periosteal reaction. These findings eliminate a degenerative process or radiation-induced osteonecrosis but do not distinguish between a neoplastic and infectious process. A PET scan showed marked uptake in the distal clavicle, which is more consistent with a malignant neoplastic process than a reactive process, like that of an infection. These findings, combined with the cellular atypia and bone formation on the biopsy specimen, confirm the diagnosis of radiation-associated sarcoma. In this older patient, radiation-associated sarcoma appears in an unusual location secondary to her previous radiation treatment in that region, which can occur 3 to 50 years after previous radiation therapy. Shaheen M, Deheshi BM, Riad S, et al: Prognosis of radiation-induced bone sarcoma is similar to primary osteosarcoma. Clin Orthop Relat Res 2006;450:76-81.

Small vesicles on the fingers of a health care worker suggest a herpetic infection, and the management of choice is observation. Incision and drainage may result in a bacterial infection. Marsupialization is used in the treatment of a chronic paronychia. Calcium gluconate is used for hydrofluoric acid burns, and copper sulfate is used for white phosphorus burns. Fowler JR: Viral Infections. Hand Clin 1989;5:613-627.

The radiographs show a small minimally displaced radial head fracture that is amenable to nonsurgical management. Early range-of-motion exercises will best restore function and minimize stiffness. A long arm cast for any length of time will result in severe elbow stiffness. Morrey BF: Radial head fracture, in Morrey BF (ed): The Elbow and Its Disorders, ed 3. Philadelphia, PA, WB Saunders, 2000, pp 341-364.

The studies show marginal syndesmophyte formation characteristic of ankylosing spondylitis. These patients typically have diffuse ossification of the disk space without large osteophyte formation. DISH typically presents with large osteophytes, referred to as nonmarginal syndesmophytes. In this patient, the zygoapophyseal joints are fused rather than degenerative as would be seen in rheumatoid arthritis, and the costovertebral joints are also fused. Osteopetrosis does not normally ankylose the disk space. McCullough JA, Transfeldt EE: Macnab's Backache, ed 3. Baltimore, MD, Williams and Wilkins, 1997, pp 190-194.

The patient has the typical history and presentation of transient synovitis of the hip, a condition that is more common in children age 2 to 5 years but which may affect children up to 12 years. The discomfort typically is noted on awakening, and the child will refuse to walk. Later in the day, the pain commonly improves and the child can walk but will have a limp. Mild to moderate restriction of hip abduction is the most sensitive range-of-motion restriction. The extent of the evaluation for transient synovitis depends on the intensity and duration of symptoms. Because she has been afebrile for the past 24 hours, observation is the management of choice. In the differential diagnosis of suspected transient synovitis, septic arthritis of the hip is the primary disorder to exclude. Osteomyelitis of the proximal femur also should be considered. In most patients, clinical examination will differentiate of these disorders to a reasonable certainty. Plain radiographs are normal in the early stage of an infectious process. Ultrasonography shows increased fluid in the hip joint in both transient synovitis and septic arthritis. MRI can differentiate the two conditions; however, this test would require general anesthesia and is not required in most patients in this age group. If a child with transient synovitis has a concurrent infectious process such as an upper respiratory tract infection or otitis media, the temperature will most likely be elevated. In this situation, a full evaluation for an infectious process and initiation of IV antibiotics should be considered. This would include radiographs, CBC count, erythrocyte sedimentation rate, blood cultures, aspiration of the hip joint, and IV antibiotics. Del Beccaro MA, Champoux AN, Bockers T, Mendelman PM: Septic arthritis versus transient synovitis of the hip: The value of screening laboratory tests. Annals Emerg Med 1992;21:1418-1422.

Whereas a patient age of older than 50 years used to be a contraindication for open reduction and internal fixation of displaced intra-articular calcaneal fractures, new data suggest that the presence of associated medical comorbidities that affect wound healing such as smoking, diabetes mellitus, and peripheral vascular disease are more relevant to postoperative functional outcome. Surgical treatment of Sanders II and III displaced intra-articular calcaneal fractures with initial Bohler angles of > 15 degrees results in better outcomes as compared to nonsurgical management. Indications for primary fusion might include Sanders IV fractures in which articular congruity or Bohler angles cannot be restored. Given the condition of the soft tissues at presentation, delayed fixation is recommended. Herscovici D Jr, Widmaier J, Scaduto JM, et al: Operative treatment of calcaneal fractures in elderly patients. J Bone Joint Surg Am 2005;87:1260-1264. Buckley R, Tough S, McCormack R, et al: Operative compared with nonoperative treatment of displaced intra-articular calcaneal fractures: A prospective, randomized, controlled multicenter trial. J Bone Joint Surg Am 2002;84:1733-1744.

The most likely diagnosis is chronic multifocal osteomyelitis. This is a culture-negative polyostotic disease that is most commonly found in young people. The treatment of choice is anti-inflammatory drugs. The pathology does not suggest eosinophilic granuloma. Antiviral therapy, broad-spectrum antibiotics, and surgical resection are not indicated for this disease.

Mechanical loosening of the hip is best revealed by serial radiographs of the prosthetic joint. None of the other methods of evaluation is considered reliable in diagnosing mechanical loosening. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 455-492.

The increased emphasis on restoring offset in total hip arthroplasty has implications for the forces applied to the components and the fixation interfaces. Static analysis has shown that with an increased affect, joint reaction force on the articulation is decreased. When the resultant load on the hip is "out of plane" (ie, directed anterior to posterior), there is increased torsion where the stem is turned into more retroversion. Buckwalter JA, Einhorn TA, Simon SR (eds): Orthopaedic Basic Science, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 134-180. Hurwitz DE, Andriaacchi TP: Biomechanics of the hip, in Callaghan J, Rosenberg AG, Rubash HE (eds): The Adult Hip. Philadelphia, PA, Lippincott-Raven , 1998.

The 1,2 intercompartmental supraretinacular artery is a branch of the radial artery. The vessel provides a reliable source of vascularized bone graft with an adequate pedicle length for use in scaphoid nonunions. Sheetz KK, Bishop AT, Berger RA: The arterial blood supply of the distal radius and ulna and its potential use in vascularized pedicled bone grafts. J Hand Surg 1995;20:902-914.

The treatment of choice for proximal pole scaphoid fractures is open reduction and internal fixation with a differential pitch screw via a dorsal approach. Healing rates of 100% have been reported for these acute fractures. Casting results in slow healing, with recommendations including 16 weeks or more in a cast. Vascularized bone grafts are not indicated for acute fractures. Rettig ME, Raskin KB: Retrograde compression screw fixation of acute proximal pole scaphoid fractures. J Hand Surg 1999;24:1206-1210.

The MRI scan reveals a L4-L5 foraminal disk herniation originating from the L4-5 disk space that has migrated up into the foramen, compressing the left L4 nerve root. There is normal distribution of the roots in the cerebrospinal fluid, excluding arachnoiditis as a diagnosis, and disk herniation in this location would not result in cauda equina syndrome or myelopathy.

Transphyseal fractures of the proximal femur at birth are more likely to occur in large newborns after a difficult delivery. At rest, the patients are comfortable and show a pseudoparalysis; however, passive motion of the lower extremity results in discomfort. Teratologic hip dislocations will have a positive Galeazzi sign, but are not painful. Development of a septic hip would be unlikely within 12 hours postpartum. Congenital coxa vara is typically painless. Postpartum ligamentous laxity might account for a positive Ortolani sign, but is painless. Weinstein JN, Kuo KN, Millar EA: Congenital coxa vara: A retrospective review. J Pediatr Orthop 1984;4:70-77.

The patient has a supple plantigrade foot that would benefit from a drop foot brace to prevent catching of the toes. Tendon transfer should not be considered until the patient has undergone bracing. Achilles tendon lengthening is not necessary because the foot is plantigrade and flexible. Nerve grafting is not indicated because of the length of time the peroneal nerve palsy has been present. Dehne R: Congenital and acquired neurologic disorders, in Mann RA, Coughlin MJ (eds): Surgery of the Foot and Ankle, ed 7. St Louis, MO, Mosby, 1999, vol 1, pp 552-553.

Fractures through the cartilage on the inferior pole of the patella, the so-called sleeve fracture, are often difficult to diagnose because of the paucity of ossified bone visible on the radiographs. If the fracture is missed and the fragments are widely displaced, the patella may heal in an elongated configuration that may result in compromise of the extensor mechanism function. The treatment of choice is open reduction and internal fixation using a tension band wire technique to achieve close approximation of the fragments and restore full active knee extension. Heckman JD, Alkire CC: Distal patellar pole fractures: A proposed common mechanism of injury. Am J Sports Med 1984;12:424-428.

MRI-arthrography has been shown to be an accurate technique for assessing the glenoid labrum in patients with suspected labral tears. Often standard MRI technique will not identify labral lesions. The use of MRI-arthrography with an intra-articular injection of gadolinium provides improved visualization of labral lesions. Bencardino and associates demonstrated a sensitivity of 89%, a specificity of 91%, and an accuracy of 90% in detecting labral lesions. SLAP lesions can be visualized on coronal oblique sequences as a deep cleft between the superior labrum and the glenoid that extends well around and below the biceps anchor. Often, contrast will diffuse into the labral fragment, causing it to appear ragged or indistinct. Applegate GR, Hewitt M, Snyder SJ, et al: Chronic labral tears: Value of magnetic resonance arthrography in evaluating the glenoid labrum and labral-bicipital complex. Arthroscopy 2004;20:959-963. Bencardino JT, Beltran J, Rosenberg ZS, et al: Superior labrum anterior-posterior lesions: Diagnosis with MR arthrography of the shoulder. Radiology 2000;214:267-271.

The obturator vessels and nerve pass along the lateral pelvic wall along the true pelvic brim (nerve lies anterior to the vessels and lies on the obturator internus muscle) and descend into the obturator groove at the upper portion of the obturator foramen. Higuchi T: Normal anatomy and magnetic resonance appearance of the pelvis, in Takahashi HE, Morita T, Hotta T, et al (eds): Operative Treatment of Pelvic Tumors. Tokyo, Japan, Springer-Verlag, 2003, pp 4-21.

Current literature supports the use of reinforcement cages for the reconstruction of failed, loosened acetabular components associated with major bone loss as seen in this patient. Although results of revision using the so-called jumbo cup with screws generally have been good, the amount of bone loss and medial wall penetration shown here and the likelihood of pelvic discontinuity precludes the use of that technique. With either technique, bone grafting of remaining defects is recommended. Sporer SM, O'Rourke M, Paprosky WG: The treatment of pelvic discontinuity during acetablular revision. J Arthroplasty 2005;20:79-84.

The patient has an oligotrophic nonunion of the distal femoral fracture. Although the proximal fracture appears incompletely united, it was stable at exchange nailing. The treatment of choice is exchange reamed nailing to at least 2 mm above the nail in place. Bone grafting is debatable. Recent studies have shown a 70% to 75% success rate with exchange nailing only, so in nonhypertrophic nonunions, bone grafting can be considered. Nonsurgical management consisting of observation or external stimulation runs the risk of implant failure. Plate fixation is acceptable but is considered a second choice because of the need to consider stabilization of the proximal fracture until union is achieved. Also, plate fixation definitely requires bone grafting. Webb LX, Winquist RA, Hansen ST: Intramedullary nailing and reaming for delayed union or nonunion of the femoral shaft: A report of 105 consecutive cases. Clin Orthop 1986;212:133-141. Weresh MJ, Hakanson R, Stover MD, et al: Failure of exchange reamed intramedullary nailing for ununited femoral shaft fractures. J Orthop Trauma 2000;14:335-338.

This is a case of synovial sarcoma. The radiograph shows some soft-tissue swelling in the upper arm. The MRI scans show a lesion that has increased signal on T2-weighted images and low signal on T1-weighted images. There is a suggestion of a large cystic component to this lesion. The pathology shows a biphasic population of cells, a spindle cell component, and an epithelioid component. Up to 20% of synovial cell sarcomas have areas of cyst formation. The most common cytogenetic translocation with synovial cell sarcoma is X; 18. The 11; 22 translocation is most commonly associated with Ewing's sarcomas; the 12; 22 translocation is most commonly associated with clear cell sarcomas; the 2; 13 translocation is most commonly associated with alveolar rhabdomyosarcomas, and the 12; 16 translocation is most commonly associated with myxoid liposarcomas. Kawai A, Woodruff J, Healey JH, et al: SYT-SSX gene fusion as a determinant of morphology and prognosis in synovial sarcoma. New Engl J Med 1998;338:153-160.

Although previous theories on acetabular wear implicated fatigue cracking and delamination as primary wear mechanisms, these have actually manifested as major modes of polyethylene wear in knees. The primary mechanism of wear in polyethylene acetabular components appears to be adhesion and abrasion. In an analysis of 128 components retrieved at autopsy or revision surgery, wear appeared to occur mostly at the surface of the components and was the result of large strain plastic deformation and orientation of the surface layers into fibrils that subsequently ruptured during multidirectional motion. It was also shown conclusively that 32-mm heads displayed significantly more wear (volumetric wear) than either 22-mm or 26-/28-mm heads (1-mm increase in size increased volumetric wear by 10%). The wear at the articulating surface was characterized by highly worn polished areas superiorly and less worn areas inferiorly separated by a ridge. Abrasion was very common, occurring after adhesion and plastic deformation of polyethylene fibrils, and abrasion secondary to third-body wear. Wear rates decreased with longer survival of components, indicating a "bedding in" phenomenon, arguing against oxidative and fatigue wear. Crevice corrosion occurs in fatigue cracks with low oxygen tension (under screw heads, etc). Oscillatory fretting consists of cyclical abrading of the outer surface from small movements. Fatigue and delamination is predominant in total knee arthroplasty where stresses are maximum just below the surface of the polyethylene component, causing fatigue over time with subsequent delamination. In contrast, hip wear occurs primarily at the surface of the polyethylene component. Jasty M, Goetz DD, Bragdon CR, et al: Wear of polyethylene acetabular components in total hip arthroplasty: An analysis of one hundred and twenty-eight components retrieved at autopsy or revision operations. J Bone Joint Surg Am 1997;79:349-358. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 47-53. Bell CJ, Walker PS, Abeysundera MR, et al: Effect of oxidation on delamination of ultrahigh-molecular-weight polyethylene tibial components. J Arthroplasty 1998;13:280-290.

The major criteria for the diagnosis of fat embolism syndrome include hypoxemia (PaO2 of less than 60 mm Hg), central nervous system depression, and a petechial rash that is most often located in the axillae, conjunctivae, and palate. The rash is often transient. Tachycardia, pyrexia, anemia, thrombocytopenia, and the presence of fat in the urine are all considered minor criteria. To establish the diagnosis of fat embolism syndrome, one major and four minor signs should be present. Pulmonary embolism, which is the major differential diagnosis, usually is not associated with conjunctival petechia or thrombocytopenia.

While difficult to appreciate on the AP radiograph of the shoulder, the increased physeal signal demonstrated on the axial MRI scan is consistent with a nondisplaced growth plate fracture. A comparison radiograph of the left shoulder also could be considered and the injured shoulder evaluated for physeal widening. Proximal humeral fractures in children are somewhat unusual, representing less than 1% of all fractures seen in children and only 3% to 6% of all epiphyseal fractures. Physeal injuries are classified according to the Salter-Harris classification scheme. Salter-Harris type I fractures represent approximately 25% of physeal injuries to the proximal humerus in adolescents. The proximal humeral physis is responsible for 80% of the longitudinal growth of the humerus; therefore, there is tremendous potential for remodeling of fractures in this region. Management for nondisplaced Salter-Harris type I fractures is limited to a short period of immobilization followed by a gradual return to activities as clinical symptoms resolve. Curtis RJ, Rockwood CA Jr: Fractures and dislocations of the shoulder in children, in Rockwood CA Jr, Matsen FA III (eds): The Shoulder. Philadelphia, PA, WB Saunders, 1990, pp 991-1007.

It is important that the radii of a metal-on-metal head to cup articulation be such that there is polar contact. As the radii become closer to equal, conditions favor higher frictional torque and equatorial seizing. The "bedding in" of metal-on-metal surfaces and their stiffness are both components of the properties considered in the design of polar contact surfaces.

Because the radiographs reveal poor regenerate bone, especially anteriorly and laterally, the first step in management is to slow the distraction rate. If this does not solve the problem, temporary reversal of the distraction, or "accordionization," can be used to induce a greater healing response. Maintaining the same distraction rate will further impair regenerate formation and delay healing. Bone grafting should be reserved as an option if decreasing the distraction rate or alternating a week of compression with a week of distraction fails to improve the callus formation. Repeat corticotomy is performed in patients with premature consolidation. Raney EM: Limb-length discrepancy, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1519-1526.

Corrective osteotomy of fibular malunions, with appropriate lengthening, even in the presence of early arthritis, has been shown to decrease ankle pain and increase stability. Reduction and bone grafting of the medial malleolar nonunion is also needed. There is no evidence supporting the use of intra-articular steroids or hyaluronic acid in the ankle joint. Lateral talar displacement of even 1 mm has been reproducibly shown to decrease tibiotalar contact by 40% to 42%, causing a predisposition to arthritis. Weber D, Friederich NF, Muller W: Lengthening osteotomy of the fibula for post-traumatic malunion: Indication, technique and results. Int Orthop 1998;22:149-152. Lloyd J, Elsayed S, Hariharan K, et al: Revisiting the concept of talar shift in ankle fractures. Foot Ankle Int 2006;27:793-796. Offierski CM, Graham JD, Hall JH, et al: Later revision of fibular malunion in ankle fractures. Clin Orthop Relat Res 1982;171:145-149.

The fracture is a both-column fracture in the Judet/Letournel classification and a C3 in the AO classification. There is extension into the sacroiliac joint along the pelvic brim and comminution along the posterior column above the sciatic notch. Both the anterior and posterior columns are separately broken and displaced. However, the defining feature of a both-column pattern, as seen in this patient, is that all articular fragments are on fracture fragments and no joint surface is left intact to the axial skeleton above. The use of three-dimensional images makes it easier to view the location of the fracture fragments and the amount and direction of displacement. Helfet DL, Beck M, Gautier E, et al: Surgical techniques for acetabular fractures, in Tile M, Helfet DL, Kellam JF (eds): Fractures of the Pelvis and Acetabulum. Philadelphia, PA, Lippincott Williams & Wilkins, 2003, pp 533-603. Tile M: Describing the injury: Classification of acetabular fractures, in Tile M, Helfet DL, Kellam JF (eds): Fractures of the Pelvis and Acetabulum, ed 3. Philadelphia, PA, Lippincott Williams & Wilkins, 2003, pp 427-475.

The correct progression of the annular and cruciform pulley in the digits is A1, A2, C1, A3, C2, A4, C3. The two cruciform pulleys are collapsible elements adjacent to the more rigid annular pulleys of the flexor tendon sheath. This arrangement enables unrestricted flexion of the proximal interphalangeal joint. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics, ed 2. Philadelphia, PA, Lippincott-Raven, 1994, pp 176-186.

Biomechanical ligament sectioning studies have implicated both the superior glenohumeral and coracohumeral ligaments as restraints to inferior translation when the shoulder is in 0 degrees of abduction and neutral rotation. Although there is controversy over the significance of each ligament, both are involved to some degree. The middle glenohumeral ligament is more important in the midranges of abduction, and the inferior ligament is more important at 90 degrees of abduction. The coracoacromial and coracoclavicular ligaments play no role in glenohumeral restraint. Warner JJ, Deng XH, Warren RF, et al: Static capsuloligamentous restraints to superior-inferior translation of the glenohumeral joint. Am J Sports Med 1992;20:675-685.

Soft-tissue sarcomas generally are treated with radiation therapy and wide surgical resection. In this patient, involvement of most of the posterior calf compartment and circumferential involvement of the posterior tibial and peroneal neurovascular bundle makes limb salvage impractical. Any attempt at wide surgical resection would leave a poorly functioning limb with questionable surgical margins. A high below-knee amputation would be the best option. Radiation therapy alone is contraindicated. Lindberg RD, Martin RG, Romsdahl MM, et al: Conservative surgery and post-operative radiotherapy in 300 adults with soft tissue sarcoma. Cancer 1981;47:2391-2397. Sim FT, Frassica FS, Frassica DA: Soft tissue tumors: Diagnosis, evaluation, and management. J Am Acad Orthop Surg 1994;2:202-211.

The extensor digiti mini quinti is most typically a tendon with two slips. The abductor pollicis longus has multiple slips that insert in order of frequency on the base of the first metacarpal, trapezium, and thenar muscles. The extensor pollicis longus, extensor carpi radialis brevis, and extensor indicis proprius consistantly have only one slip. von Schroeder HP, Botte MJ: Anatomy of the extensor tendons of the fingers: Variations and multiplicity. J Hand Surg Am 1995;20:27-34.

All of the above can be associated with myelomeningocele, but talipes equinovarus occurs in 50% to 90% of patients with myelomeningocele. Congenital vertical talus is rarely associated with any neuromuscular diseases other than myelomeningocele but is not the most common deformity in myelomeningocele. Stans AA, Kehl DK: The pediatric foot, in Baratz ME, Watson AD, Imbriglia JE (eds): Orthopaedic Surgery: The Essentials. New York, NY, Thieme, 1999, pp 702-703.

The radiographs show classic hinge abduction. The diagnostic feature is the failure of the lateral epiphysis to slide under the acetabular edge with abduction, and the abduction view shows medial dye pooling because of distraction of the hip joint. Persistent hinge abduction has been shown to prevent femoral head remodeling by the acetabulum. Radiographic changes are characteristic of severe involvement with Legg-Calve-Perthes disease.The Catterall classification cannot be well applied without a lateral radiograph, but this degree of involvement would likely be considered a grade III or IV. Because the lateral pillar is involved, this condition would be classified as type C using the Herring lateral pillar classification scheme.

Complications of thermal capsule shrinkage or accelerated rehabilitation include capsule ablation. Since the original surgery did not include labral reattachment, findings of a Bankart lesion or a glenoid fracture from a nontraumatic injury are unlikely. Subscapularis detachment or biceps subluxation is a postoperative complication of open repairs. Failure of early postoperative instability treatment should not produce loose bodies. Abrams JS: Thermal capsulorrhaphy for instability of the shoulder: Concerns and applications of the heat probe. Instr Course Lect 2001;50:29-36.

BMPs signal through the activation of a transmembrane serine/threonine kinase receptor that leads to the activation of intracellular signaling molecules called SMADs. There are currently eight known SMADs, and the activation of different SMADs within a cell leads to different cellular responses. The other mediators are not believed to be directly involved with BMP signaling. Lieberman J, Daluiski A, Einhorn TA: The role of growth factors in the repair of bone: Biology and clinical applications. J Bone Joint Surg Am 2002;84:1032-1044. Li J, Sandell LJ: Transcriptional regulation of cartilage-specific genes, in Rosier RN, Evans C (eds): Molecular Biology in Orthoapedics, Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 21-24.

Ankle sprains most commonly involve injury to the lateral collateral ligaments of the ankle (anterior talofibular, posterior talofibular, and calcaneofibular) from an inversion mechanism of injury. A different entity has been more recently described that involves an external rotation mechanism of injury that widens the ankle mortise and disrupts the anterior inferior tibiofibular ligament. Deltoid ligament and extensor retinaculum injuries do occur, although infrequently, and involve eversion and extreme plantar flexion mechanisms, respectively. Last RJ: Anatomy: Regional and Applied, ed 6. London, England, Churchill Livingstone, 1978, p 182. Kaye RA: Stabilization of ankle syndesmosis injuries with a syndesmosis screw. Foot Ankle 1989;9:290-293. Baxter DE: The Foot and Ankle in Sports. St Louis, MO, Mosby-Year Book, 1995, p 30.

The change noted is focal and confined to the cortex, sparing the opposite side, both lower extremities, and the subcortical waveforms, making all the choices unlikely with the exception of carotid compression with focal cortical ischemia. This may be associated with poor collateral flow from the opposite hemisphere due to an incomplete circle of Willis. Drummond JC, Englander RN, Gallo CJ: Cerebral ischemia as an apparent complication of anterior cervical discectomy in a patient with an incomplete circle of Willis. Anesth Analg 2006;102:896-899.

Using mechanical failure of fixation as the end point, Udomkiat and associates demonstrated a 12-year survivorship of 99.1% for titanium press-fit acetabular components without supplementary screw fixation. This study suggests that it is unlikely that the use of supplementary screws would lead to improved results. In addition, polyethylene wear debris tends to migrate through screw holes and along the course of screws. Screw holes also decrease the available surface for bone ingrowth. Screws that back up may be a source of backside polyethylene wear. This suggests that screw holes and the use of screws should be avoided when they are unnecessary for cup fixation.

The history, physical examination, and radiographs indicate that the patellofemoral pain is most likely caused by excessive lateral patellar pressure and patellar maltracking. Because the radiographs reveal the lateral tilt of the patella and lateral subluxation, the treatment of choice is bilateral lateral releases with anteromedialization of the tibial tubercles. This procedure corrects not only the excessive lateral patellar pressure, but also the lateral subluxation. The use of patella-stabilizing braces or taping may provide temporary relief, but these implements are not well-tolerated and they will not change the underlying biomechanics of the knee. Simple lateral release is indicated for isolated lateral tilt, but it does not correct the lateral subluxation. The use of thermal capsular shrinkage for the medial retinaculum has not been proven to provide long-term correction of the deformity. Boden BP, Pearsall AW, Garrett We Jr, et al: Patellofemoral instability: Evaluation and management. J Am Acad Orthop Surg 1997;5:47-57.

Several large clinical studies have shown that the most common problem after elastic nailing of a femoral shaft fracture is persistent pain and irritation at the nail insertion site. Unacceptable shortening and malunion are very rare in a 7-year-old patient. Rotational malalignment also is unusual. Osteonecrosis has been reported in solid antegrade nailing but not with elastic nailing of femoral shaft fractures in skeletally immature patients. Flynn JM, Luedtke LM, Ganley TJ, et al: Comparison of titanium elastic nails with traction and a spica cast to treat femoral fractures in children. J Bone Joint Surg Am 2004;86:770-777. Flynn JM, Hresko T, Reynolds RA, et al: Titanium elastic nails for pediatric femur fractures: A multicenter study of early results with analysis of complications. J Pediatr Orthop 2001;21:4-8.

The problem with this reconstruction is the medial protrusion of the base plate. The use of a base plate with an offset stem can prevent the protrusion and thus the impingement and pain. Allograft bone or smoothing the outline with cement would be just as prominent and likely to cause pain. An ingrowth surface may improve soft-tissue attachment but would still leave the implant protruding medially and likely to cause pain. A nonstemmed tibial base plate would lead to less medial protrusion but at the expense of a smaller area for load carriage on the proximal tibia.

The contracture is too large for a Z-plasty, which allows a 75% increase in length. Excision of the scar with placement of a skin graft is prone to contracture. A posterior interosseous fasciocutaneous flap will provide enough well-vascularized tissue and is well suited to reach the first dorsal web space. Buchler U, Frey HP: Retrograde posterior interosseous flap. J Hand Surg Am 1991;16:283-292.

The patient has an early prosthesis infection as a result of hematogenous seeding from dental surgery. Irrigation and debridement with polyethylene exchange and IV antibiotics have been successful in early postoperative infections; it is less likely to be effective for a late hematogenous infection. Immediate total component exchange also may be effective, but it should be reserved for failure of irrigation and debridement. Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 323-337.

Examination reveals an irritable hip, creating a differential diagnosis of transient synovitis versus pyogenic hip arthritis. Kocher and associates described four criteria to help predict the presence of infection: inability to bear weight, fever, ESR of more than 40 mm/h, and a peripheral WBC count of more than 12,000/mm3. This patient meets three of the four criteria, with a positive predictive value of 73% to 93% for joint infection. Therefore, aspiration of the hip is warranted, with a high likelihood that emergent hip arthrotomy will be indicated. Ideally, intravenous antibiotics should be administered after culture material has been obtained from needle aspiration of the hip. An urgent bone scan is better indicated as a screening test for sacroiliitis or diskitis. If the arthrocentesis proves negative, CT or MRI of the pelvis may be indicated to rule out a pelvic or psoas abscess. Del Beccaro MA, Champoux AN, Bockers T, et al: Septic arthritis versus transient synovitis of the hip: The value of screening laboratory tests. Ann Emerg Med 1992;21:1418-1422. Kocher MS, Mandiga R, Zurakowski D, et al: Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children. J Bone Joint Surg Am 2004;86:1629-1635.

Necrotizing fasciitis is a rapidly progressive soft-tissue infection with the potential to threaten both life and limb. Patients who are immunocompromised (HIV infection, diabetes mellitus, alcohol abuse) are at increased risk. However, any patient in the immediate postoperative phase is susceptible to wound infection. Early detection is the key. Necrotizing fasciitis is primarily a surgical problem that requires urgent debridement and broad-spectrum IV antibiotics. Rapid diagnosis and prompt treatment help to reduce mortality, which may approach 30%. Debridement of the bullae and observation are not indicated. Although elevation and close follow-up may be warranted early on, in this patient, surgical debridement is the next step. Ault MJ, Geiderman J, Sokolov R: Rapid identification of group A streptococcus as the cause of necrotizing fasciitis. Ann Emerg Med 1996;28:227-230.

The first branch of the lateral plantar nerve is susceptible to entrapment beneath the deep fascia of the adductor hallucis muscle adjacent to the calcaneal attachment of the plantar fascia. This can be a cause of chronic heel pain. Additionally, the nerve is vulnerable to injury by a blind dissection in releasing the plantar fascia. The dorsal cutaneous branch of the superficial peroneal nerve supplies sensation to the dorsum of the foot. The medial calcaneal branch of the posterior tibial nerve lies in the subcutaneous tissues and innervates the skin of the heel. It is vulnerable to injury from skin incisions on the medial side of the heel. The lateral branch of the medial plantar nerve forms the second and third common digital nerves. Entrapment of the proper medial plantar nerve can occur at the master knot of Henry. This is well distal to the calcaneal attachment of the plantar fascia, and the pain usually radiates more distally in the arch, separate from heel pain. The communicating branch of the fourth common digital nerve crosses to the third common digital nerve. Therefore, the third common digital nerve receives supply from both the lateral and medial plantar nerves. This dual supply has been implicated in the increased incidence of digital neuroma of the third common digital nerve. Bordelon RL: Heel pain, in Mann RA, Coughlin MJ (eds): Surgery of the Foot and Ankle, ed 6. St Louis, MO, CV Mosby, 1993, pp 837-857. Mann RA, Baxter DE: Diseases of the nerves, in Mann RA, Coughlin MJ (eds): Surgery of the Foot and Ankle, ed 6. St Louis, MO, CV Mosby, 1993, pp 543-574.

The semitendinosus and gracilis tendons lie beneath the superficial fascia and superficial to the medial collateral ligament. The semitendinosus is located more inferior to the gracilis tendon. The sartorius is more posterior and distal as is the medial collateral ligament. The semimembranosus is posterior. Pagnani MJ, Warner JJ, O'Brien SJ, Warren RF: Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest. Am J Sports Med 1993;21:565-571.

Nonsurgical management of a symptomatic accessory navicular should be attempted prior to surgery. Good relief is often obtained with a semi-rigid orthosis with a medial arch support. Myerson MS: Foot and Ankle Disorders. Philadelphia, PA, WB Saunders, 2000, p 655.

The MRI scan shows a large mass (lipoma) in the thenar muscles of the palm. The recurrent motor branch of the median nerve innervates the thenar muscles. The anterior interosseous nerve (AIN) in the proximal forearm innervates the flexor pollicis longus, pronator quadratus, and flexor digitorum pollicis to the index and frequently the middle finger. The terminal branch of the AIN innervates only the wrist capsule. The palmar cutaneous branch of the ulnar nerve is a sensory structure to the hypothenar area. There is no commonly described recurrent branch of the ulnar nerve.

Acute cauda equina syndrome, including saddle hypesthesia and bowel/bladder incontinence, is a red flag that demands emergent evaluation with MRI and urgent surgery if compression is confirmed. Results appear to be improved if surgery is performed within 48 hours. The other treatment approaches listed are not indicated if a cauda equina syndrome is present. Ahn UM, Ahn NU, Buchowski JM, et al: Cauda equina syndrome secondary to lumbar disc herniation: A meta-analysis of surgical outcomes. Spine 2000;25:1515-1522. Shapiro S: Medical realities of cauda equina syndrome secondary to lumbar disc herniation. Spine 2000;25:348-351.

The initial treatment for peritendinitis should consist of calf stretching in an eccentric mode and physical therapy. In a recent study, this treatment has been found superior to surgical debridement in nonextensive peritendinitis and pantendinitis. A non-weight-bearing cast, while useful in reducing inflammation, will result in calf atrophy and poorly organized collagen repair. Cortisone is contraindicated because of the danger of tendon damage. Tendon debridement at this stage is not indicated. Alfredson H, Pietila T, Jansson P, Lorentzon R: Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. Am J Sports Med 1998;26:360-366.

The superior gluteal nerve is located approximately 7.82 cm above the tip of the greater trochanter as it courses through the gluteus medius. This anatomic consideration is relevant during a Hardinge approach to the hip, where excessive proximal dissection or retraction could result in nerve injury. A split of the gluteus medius of no more than 4 cm above the greater trochanter is considered safe. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, pp 333-335.

Epithelioid sarcoma is a rare soft-tissue sarcoma that most commonly arises in the hand or upper extremity, and it is frequently misdiagnosed as an infection or granuloma. It tends to have a higher incidence of lymph node metastasis than other soft-tissue sarcomas. The mainstay of treatment is wide surgical excision, even if amputation is necessary. Gupta TD, Chaudhuri P (eds): Tumors of the Soft Tissues, ed 2. Stamford, CT, Appleton and Lange, 1998, p 475.

The radiograph reveals disruption of the syndesmosis with lateral displacement of the talus and widening of the medial ankle clear space. No fibular fracture is noted, although radiographs of the entire tibia and fibula are necessary to rule out a more proximal fibula fracture. There is clear instability of the syndesmosis, and surgical stabilization is needed, either by direct repair of the ligaments or more commonly with surgical stabilization of the fibula to the tibia with screws. Functional rehabilitation and early range of motion are indicated with anterior-lateral ankle sprains but not with true instability of the syndesmosis. In anterior syndesmotic injuries in which there are no signs of instability on plain radiographs or with stressing, cast immobilization and protected weight bearing until tenderness subsides is warranted. Long leg cast immobilization is unlikely to be adequate in maintaining reduction of the syndesmosis. Repair of the talofibular ligaments or fibular osteotomy does not address the pathology at the syndesmosis. Chronic syndesmotic disruption is likely to lead to chronic ankle pain and early arthrosis. Wuest TK: Injuries to the distal lower extremity syndesmosis. J Am Acad Orthop Surg 1997;5:172-181.

Warfarin acts by inhibiting clotting factors II, VII, IX, X. The actual mechanism of action is by inhibition of hepatic enzymes, vitamin K epoxide, and perhaps vitamin K reductase. This inhibition results in lack of carboxylation of vitamin K-dependent proteins (II, VII, IX, X). The anticoagulant effect of warfarin can be reversed with vitamin K or fresh-frozen plasma. The use of alcohol may lead to liver dysfunction and an even more limited margin of available factors. Lieberman JR, Wollaeger J, Dorey F, et al: The efficacy of prophylaxis with low-dose warfarin for prevention of pulmonary embolism following total hip arthroplasty. J Bone Joint Surg Am 1997;79:319-325.

The MRI scans show coronal oblique and sagittal oblique views of a partial articular surface supraspinatus tear or tendon avulsion (PASTA lesion). The arthroscopic view is a posterior portal of the glenohumeral joint viewing the articular surface of the supraspinatus. These tears are a common source of shoulder pain and are often amenable to transtendon arthroscopic repair without detachment of the intact bursal surface. Sanders TG, Miller MD: A systematic approach to magnetic resonance imaging interpretation of sports medicine injuries of the shoulder. Am J Sports Med 2005;33:1088-1105. McConville OR, Iannotti JP: Partial-thickness tears of the rotator cuff: Evaluation and management. J Am Acad Orthop Surg 1999;7:32-43.

As the chance of success of lumbosacral fusion increases with the stiffness and rigidity of the construct, fixation and stiffness improve with fixation into both the upper sacrum and the ilium. In a review of individuals treated with long constructs to the pelvis for adult scoliosis, Islam and associates reported that the rate of pseudarthrosis was significantly lower with sacral and iliac fixation compared with sacral fixation alone or iliac fixation alone. Iliac screws provide significant fixation anterior to the instantaneous axis of rotation for flexion and extension, as well as provides resistance to lateral bending and rotational forces. Numerous biomechanical studies support the concept of increasing biomechanical stabilization with increased fixation from the sacrum to the ilium. Islam NC, Wood KB, Transfeldt EE, et al: Extension of fusions to the pelvis in idiopathic scoliosis. Spine 2001;26:166-173. O'Brien N, et al: Sacral pelvic fixation and spinal deformity, in DeWald RL (ed): Spinal Deformities: A Comprehensive Text. New York, NY, Thieme, 2003, pp 601-614.

Elastofibroma is a rare tumor that most commonly occurs in adults who are older than age 55 years. The lesions usually grow between the chest wall and the scapula, and 10% are bilateral. Histologic analysis shows that they are composed of equal amounts of elastin and collagen with occasional fibroblasts. Briccoli A, Casadei R, Di Renzo M, Favale L, Bacchini P, Bertoni F: Elastofibroma dorsi. Surg Today 2000;30:147-152.

The Allen and Ferguson mechanistic classification system is a useful tool for evaluating cervical spine injuries. Cervical fractures are classified as compressive extension, distractive extension, compressive flexion, distractive flexion, vertical compression, and lateral flexion. The patient has a distractive flexion injury.

The patient has the typical end stage residuals from long-standing Charcot-Marie-Tooth disease. Initial management consisting of shoe wear modifications and orthotic devices is preferred, but these are not successful when the disease process has progressed. Surgical correction with calcaneal osteotomy or Achilles tendon lengthening and Steindler stripping is not indicated in the presence of significant hindfoot arthritis. Because this patient has findings consistent with hindfoot arthritis, a triple arthrodesis with correction of the cavus deformity is the preferred treatment. Roper BA, Tibrewal SB: Soft tissue surgery in Charcot-Marie-Tooth disease. J Bone Joint Surg Br 1989;71:17-20.

Internal impingement of the shoulder is a leading cause of shoulder pain in the throwing athlete. The primary lesion in pathologic internal impingement is excessive tightening of the posterior band of the inferior glenohumeral ligament complex. To obtain an accurate assessment of true glenohumeral rotation, the scapula is stabilized during examination. A loss of 20 degrees or more of internal rotation, as measured with the shoulder positioned in 90 degrees of abduction, indicates excessive tightness of the posterior band of the inferior glenohumeral ligament complex. Burkhart SS, Morgan CD, Kibler WB: The disabled throwing shoulder: Spectrum of pathology. Part I: Pathoanatomy and biomechanics. Arthroscopy 2003;19:404-420.

Complications of medial sesamoidectomy include stiffness, claw toe, and hallux valgus. Each sesamoid sits within its respective head of the flexor hallucis brevis tendon. Excision of one sesamoid can result in slack in its flexor hallucis brevis tendon; therefore, it is imperative to preserve or repair the flexor hallucis brevis tendon when removing the medial sesamoid. Dedmond BT, Cory JW, McBryde A Jr: The hallucal sesamoid complex. J Am Acad Orthop Surg 2006;14:745-753.

The MRI scan shows near complete involvement of the femoral head with bone marrow changes and some collapse of the necrotic segment. This is most suggestive of osteonecrosis.

The authors of several studies conducted in Europe have reported promising results in the short- and medium-term with use of a reversed or inverted shoulder implant. The most recent investigation, a multicenter study in Europe in which 77 patients (80 shoulders) with glenohumeral osteoarthritis and a massive rupture of the rotator cuff were treated with the Delta III prosthesis, described an improvement in the mean constant score of 42 points, an increase of 65 degrees in forward elevation, and minimal or no pain in 96% of the patients. Hemiarthroplasty, the "nonconstrained" option, has long been the standard of care for rotator cuff tear arthropathy. However, careful examination of the literature reveals that the results have not been uniform. Favard L, Lautmann S, Sirveaux F, et al: Hemiarthroplasty versus reverse arthroplasty in the treatment of osteoarthritis with massive rotator cuff tear, in Walch G, Boileau P, Mole D (eds): 2000 Shoulder Prosthesis Two to Ten Year Follow-Up. Montpellier, France, Sauramps Medical, 2001, pp 261-268. Frankle M, Siegal S, Pupello D, et al: The reverse shoulder prosthesis for glenohumeral arthritis associated with severe rotator cuff deficiency: A minimum two-year follow-up study of sixty patients. J Bone Joint Surg Am 2005;87:1697-1705.

A two-dimensional stress analysis has been used to study the effects of some of the factors leading to early fatigue failure of the femoral stem in total hip arthroplasty. It has been demonstrated that loss of proximal stem support at the level of the calcar femorale and subsequent stem stress can lead to fatigue failure. In addition, the role of body weight and range of cyclic stress fluctuation play an important role in fatigue life under conditions where the stem has lost proximal support. These results indicate that stem design could be improved by incorporating some means of adequate support at the calcar femorale where maximum tensile stresses are found to occur. Femoral component fracture is a rare but well-documented complication after total hip arthroplasty. Historically, most stem fractures occur at the middle third of the implant where proximal stem loosening and solid distal stem fixation result in cantilever bending and eventual fatigue failure. The component shown is a modular fluted cementless stem that occasionally fractures at the modular junction in patients with poor proximal bone support. Andriacchi TP, Galante JO, Belytschko TB, et al: A stress analysis of the femoral stem in total hip prostheses. J Bone Joint Surg Am 1976;58:618-624.

Near complete correction and rebalancing of the spine can be achieved by hemivertebral resection that may be done as either a simultaneous or a staged procedure in the young patient. This eliminates the problem of future progression and possible development of compensatory curves. Nonsurgical management is not indicated in congenital scoliosis. Convex hemiepiphyseodesis is best suited for patients younger than age 5 years who have a short curve caused by fully segmented hemivertebrae that correct to less than 40 degrees with the patient supine. Hemiepiphyseodesis and isolated posterior fusion are not indicated. Bradford DS, Boachie-Adjei O: One-stage anterior and posterior hemivertibral resection and arthrodesis for congenital scoliosis. J Bone Joint Surg Am 1990;72:536-540.

The prevalence of postoperative ileus associated with total joint arthroplasty has been reported to be as high as 3%. Metabolic abnormalities such as hypokalemia are believed to contribute to the onset of ileus and Ogilvie's syndrome (acute pseudo-obstruction of the colon). Prolonged bed rest also has been associated with the development of ileus and Ogilvie's syndrome. Untreated Ogilvie's syndrome can result in cecal perforation. Ileus usually is not accompanied by mechanical obstruction. Antibiotic administration and the type of anesthesia used have not been correlated with development of ileus. Administration of warfarin has been associated with elevated prothrombin time/partial thromboplastin time and international normalized ratio levels when ileus is managed with a nasogastric tube and suction. Metabolic imbalances must be corrected to reverse the ileus process. Iorio R, Healy WL, Appleby D: The association of excessive warfarin anticoagulation and postoperative ileus after total joint replacement surgery. J Arthroplasty 2000;15:220-223.

Arthrodesis of the failed infected total knee arthroplasty may be accomplished by external fixation, intramedullary rod fixation, and dual plates and screws. External fixation runs the risk of pin tract infection, although after its removal, there are no metal surfaces left in place. Intramedullary rods have been used successfully in the treatment of infected total knees, although they also leave metal within the region of the infection. The dual plate technique of knee fusion is useful in patients with rheumatoid arthritis who require fusion in the absence of infection because it provides good initial stability and avoids the use of external pins. However, in the face of infection, the large surface area of the screws and plates may serve as a site for bacteria to hide within a glycocalyx and make eradication of the infection almost impossible.

A sulcus sign represents inferior subluxation of the shoulder. The elimination of this sign and correction of the inferior subluxation is best achieved through either an open or arthroscopic rotator interval closure. A SLAP repair stabilizes the biceps anchor but does not affect the sulcus sign. A Bankart repair, which corrects anterior-inferior laxity, is not sufficient to eliminate a sulcus sign. Subacromial decompression and supraspinatus repairs have no effect on inferior subluxation. Field LD, Warren RF, O'Brien SJ, et al: Isolated closure of rotator interval defects for shoulder instability. Am J Sports Med 1995;23:557-563.

Billote and associates compared patients with normal baseline hemoglobin levels who did and did not donate autologous blood prior to total hip arthroplasty. No patients received allogeneic blood perioperatively, and the autologous donors had significantly lower hemoglobin levels at the time of surgery and in the recovery room. Of the autologous donors, 69% received an autologous transfusion. The authors concluded that autologous donation was unnecessary in patients undergoing primary total hip arthroplasty who had a normal hemoglobin. Billote D, Glisson SN, Green D, Wixson RL: A prospective, randomized study of preoperative autologous donation for hip replacement surgery. J Bone Joint Surg Am 2002;84:1299-1304.

Tornetta and associates and Yang and associates found that nearly half of all femoral neck fractures associated with femoral shaft fractures were being missed at their institution. On the basis of the delayed diagnosis of these injuries, a best-practice protocol was developed by the attending trauma surgeons for the evaluation of the femoral neck in patients with a femoral shaft fracture. This protocol includes a preoperative AP internal rotation radiograph of the hip, a fine-cut (2-mm) CT scan through the femoral neck (as a part of the initial trauma scan), and an intraoperative fluoroscopic lateral evaluation of the hip just prior to fixation of the femoral shaft. In addition, postoperative AP and lateral radiographs of the hip are made in the operating room to specifically evaluate the femoral neck before the patient is awakened. They found that fine-cut CT (2 mm was the best screening tool in this group of patients) identified 12 of the 13 fractures, whereas 8 of the 13 fractures were visible on the dedicated preoperative AP internal rotation hip radiographs. Tornetta P III, Kain MS, Creevy WR: Diagnosis of femoral neck fractures in patients with a femoral shaft fracture: Improvement with a standard protocol. J Bone Joint Surg Am 2007;89:39-43.

The most commonly injured neurovascular structure during an anterior approach for the repair of a distal biceps tendon rupture is the lateral antebrachial cutaneous nerve. This structure is located lateral to the biceps tendon and in a superficial location just deep to the subcutaneous layer. The antecubital vein is medial and superficial with the brachial artery and median nerve also medial to the biceps tendon but deep to the common flexors. The posterior interosseous nerve is deep within the supinator muscle and can be injured in the deep dissection or through the posterior approach when using a two-incision approach. Kelly EW, Morrey BF, O'Driscoll SW: Complications of repair of the distal biceps tendon with the modified two-incision technique. J Bone Joint Surg Am 2000;82:1575-1581.

Gamma irradiation has long been used as a sterilization method for polyethylene. Exposure to gamma irradiation causes breakage of the chemical bonds in the polyethylene, and oxidation will occur if the material is subsequently exposed to air. The amount of oxidation and decrease in wear performance is also related to the length of time that the gamma-irradiated polyethylene is exposed to oxygen. Collier JP, Sutula LC, Currier BH, et al: Overview of polyethylene as a bearing material: Comparison of sterilization methods. Clin Orthop 1996;333:76-86. McKellop H, Shen FW, Lu B, et al: Effect of sterilization method and other modifications on the wear resistance of acetabular cups made of ultra-high molecular weight polyethylene: A hip-simulator study. J Bone Joint Surg Am 2000;82:1708-1725.

The presence of any curve greater than 20 degrees in a nonambulatory patient with Duchenne muscular dystrophy is an indication for posterior fusion with instrumentation. Because of progressive cardiomyopathy and pulmonary deficiency, waiting until the curve is larger can increase the risk of pulmonary or cardiac complications during or following surgery. There is some disagreement as to whether all such fusions must extend to the pelvis. Bracing or other nonsurgical management is ineffective and is not indicated in this situation. Sussman M: Duchenne muscular dystrophy. J Am Acad Orthop Surg 2002;10:138-151.

The plantar-medial cutaneous nerve is at risk with the surgical approach to the medial sesamoid. It is found directly underlying an incision made at the junction of the glabrous skin of the hallux and must be identified before the approach can proceed. Transection will result in a painful neuroma that impinges on the plantar-medial surface of the toe and cause problems with shoe wear. The only other structure that lies near the surgical field is the abductor hallucis tendon which lies dorsal to the incision.