100 Orthopedic MCQs: Spine, Trauma, Sports & Joint Replacement | Comprehensive ABOS Board Review

The radiograph and intraoperative photograph show osteonecrosis with near complete head loss/collapse. A stemmed implant is more appropriate in this patient because there is very little bone to support a resurfacing implant. In a younger patient, a glenoid implant should be delayed as long as possible because of the eventual need for revision secondary to glenoid loosening and wear, especially in a young active male. The hemiarthroplasty may be converted to a total shoulder arthroplasty in the future. Levy O, Copeland SA: Cementless surface replacement arthroplasty of the shoulder: 5- to 10-year results with the Copeland mark-2 prosthesis. J Bone Joint Surg Br 2001;83:213-221.

The patient has an AP I pelvic ring disruption with minimal symphyseal widening. The best treatment is nonsurgical management and weight bearing as tolerated. This will help close the anterior pelvic ring during the healing process. Pelvic binders are excellent for acute treatment of widely displaced pelvic fractures but are not recommended for long-term use. Open reduction and internal fixation is not indicated for this injury and furthermore, the posterior ring is not injured. Matta JM: Indications for anterior fixation of pelvic fractures. Clin Orthop Relat Res 1996;329:88-96. Templeman DC, Schmidt AH, Sems SA, et al: Diastasis of the symphysis pubis: Open reduction internal fixation, in Wiss D (ed): Masters Techniques in Orthopaedic Surgery-Fractures, ed 2. Philadelphia, PA, Lippincott Williams and Wilkins, 2006, pp 639-648.

The diagnosis is myositis ossificans resulting from an injury. The initial radiograph reveals a small amount of mineralization in the soft tissues overlying the left hip. The MRI scan shows signal abnormality of the entire gluteus minimus muscle with a mineralized mass in the center. The current radiograph shows a lesion within the abductor musculature with mature ossification peripherally. The imaging studies are diagnostic and the patient is asymptomatic; therefore, the management of choice is observation with no further evaluation or treatment indicated. Miller AE, Davis BA, Beckley OA: Bilateral and recurrent myositis ossificans in an athlete: A case report and review of treatment options. Arch Phys Med Rehabil 2006;87:286-290.

The radiograph shows a bony avulsion of the ACL attachment site on the tibial spine in this skeletally immature patient. In this age group, injury often results in failure of the bony attachment site rather than the substance of the ligament. Avulsion of the patellar tendon insertion site can occur, but this structure is located at the apophysis of the tibial tubercle. The attachment site of the PCL is much more posterior. In adults, bony avulsion is more commonly associated with PCL injuries than with ACL injuries. When a small bony avulsion of the lateral capsule from the lateral tibial plateau is seen on the AP view, this finding is considered pathognomonic of an ACL injury (Segond sign) in adults. The area of the pes anserinus is anterior and distal; avulsion would be unusual. Baxter MP, Wiley JJ: Fractures of the tibial spine in children: An evaluation of knee stability. J Bone Joint Surg Br 1988;70:228-230. Meyers MH, McKeever FM: Fracture of the intercondylar eminence of the tibia. J Bone Joint Surg Am 1970;52:1677-1684.

The radiographs show a fracture-dislocation with translation in both the coronal and sagittal planes, evidence of significant instability requiring surgical stabilization. Anterior instrumentation is not as effective as posterior instrumentation in restoring stability, and because there is little bony destruction, the anterior column can be successfully reconstructed with simple realignment. The treatment of choice is multisegment posterior fusion with instrumentation. Lewandrowski KU, McLain RF: Thoracolumbar fractures: Evaluation, classification, and treatment, in Frymoyer JW, Wiesel SW (eds): The Adult and Pediatric Spine. Philadelphia, PA, Lippincott Williams and Wilkins, 2004, pp 817-843.

Deep sepsis of the shoulder following rotator cuff repair is an uncommon problem. Patients with infections of this type typically report persistent pain and are not systemically ill. They may have signs of local wound problems such as erythema, drainage, and dehiscence. Laboratory studies can be helpful in making an accurate diagnosis. Most patients will not show a significant elevation of the WBC count; however, an elevated erythrocyte sedimentation rate is nearly always present and should alert the clinician to the presence of infection. Aspiration of both subacromial and glenohumeral joint spaces is necessary to confirm the diagnosis. The most effective treatment for deep shoulder sepsis following rotator cuff repair involves extensive surgical debridement, removing all suspicious soft tissue as well as implants. Administration of appropriate antibiotic therapy is needed for complete control of the infection. Mirzayan R, Itamura JM, Vangsness CT, et al: Management of chronic deep infection following rotator cuff repair. J Bone Joint Surg Am 2000;82:1115-1121. Settecerri JJ, Pitnu MA, Rock MG, et al: Infection after rotator cuff repair. J Shoulder Elbow Surg 1994;8:105.

The natural history of the patient's hips, if left untreated, is gradual progression to dislocation. To prevent future pain, prevention of dislocation is often helpful. The patient is too old for soft-tissue releases alone. Therefore, the treatment of choice is medial release of both hips to obtain 45 degrees or better of hip abduction in conjunction with psoas tenotomy and bilateral femoral varus osteotomies. Presedo A, Oh CW, Dabney KY, et al: Soft-tissue releases to treat spastic hip subluxation in children with cerebral palsy. J Bone Joint Surg Am 2005;87:832-841.

As shown by Palm and associates from the Hip Fracture Study group, the integrity of the lateral femoral cortex in intertrochanteric hip fractures is a significant predictor of reoperation. Baumgartner and associates have shown that a tip-apex distance of greater than 25 mm is associated with a high risk of femoral head cut-out. Lastly, intertrochanteric hip fractures can be described as standard obliquity or reverse obliquity when describing the fracture pattern. Mechanistically, a reverse obliquity pattern is important to recognize because it reflects the presence or absence of a lateral buttress to which the proximal fracture fragment may compress. Palm H, Jacobsen S, Sonne-Holm S, et al: Integrity of the lateral femoral wall in intertrochanteric hip fractures: An important predictor of a reoperation. J Bone Joint Surg Am 2007;89:470-475. Sadowski C, Lübbeke A, Saudan M, et al: Treatment of reverse oblique and transverse intertrochanteric fractures with use of an intramedullary nail or a 95 degrees screw-plate: A prospective, randomized study. J Bone Joint Surg Am 2002;84:372-381.

If the Buford complex is mistakenly reattached to the neck of the glenoid, severe painful restriction of external rotation will occur. Williams MM, Snyder SJ, Buford D Jr: The Buford complex - the "cord-like" middle glenohumeral ligament and absent anterosuperior labrum complex: A normal anatomic capsulolabral variant. Arthroscopy 1994;10:241-247.

According to NASCIS III, the high-dose steroid protocol involves infusion of 30 mg/kg methylprednisolone followed by 5.4 mg/kg/h for 24 hours if the patient has sustained a spinal cord injury within the last 3 hours. The drip is continued for 48 hours if administration is started between 3 and 8 hours of the onset of neurologic deficit. No benefit has been conclusively demonstrated with steroids administered beginning 8 hours or longer after injury. Steroid use is not indicated for nerve root deficits, brachial plexus deficits, or gunshot wounds. Kellam JF, Fischer TJ, Tornetta P III, Bosse MJ, Harris MB (eds): Orthopaedic Knowledge Update: Trauma 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 319-328.

The radiographs reveal a scaphoid fracture with displacement and comminution and an unstable fracture pattern. Treatment should consist of open reduction and internal fixation. In displaced scaphoid fractures and fractures with unstable fracture patterns, closed reduction is ineffective and is likely to lead to nonunion. Limited intercarpal fusion and proximal row carpectomy are used to correct a variety of traumatic and posttraumatic problems of the wrist. Amadio PC, Taleisnik J: Fractures of the carpal bone, in Green DP, Hotchkiss RN, Pederson WC (eds): Green's Operative Hand Surgery, ed 4. Philadelphia, PA, 1999, pp 809-823. Rettig ME, Kozin SH, Cooney WP: Open reduction and internal fixation of acute displaced scaphoid waist fractures. J Hand Surg Am 2001;26:271-276. Cooney WP, Dobyns JH, Linscheid RL: Fractures of the scaphoid: A rational approach to management. Clin Orthop 1980;149:90-97.

Return to play decisions after traumatic spinal or spinal cord injury are not always clear-cut and often must be made on a patient-by-patient basis. The Torg ratio has been found to have low sensitivity in patients with large vertebral bodies. Abnormal electromyographic studies can persist in the face of normal function and do not define spinal injury. Duration of quadriplegia is not related to anatomic pathology. Findings on MRI scans or contrast-enhanced CT scans consistent with stenosis include lack of a significant cerebrospinal fluid signal around the cord, bony or ligament hypertrophy, or disk encroachment. Based on these findings, return to play should be avoided. Cantu RC, Bailes JE, Wilberger JE Jr: Guidelines for return to contact or collision sport after a cervical spine injury. Clin Sports Med 1998;17:137-146. Herzog RJ, Wiens JJ, Dillingham MF, Sontag MJ: Normal cervical spine morphometry and cervical stenosis in asymptomatic professional football players: Plain film radiography, multiplanar computer tomography, and magnetic resonance imaging. Spine 1991;16:178-186.

The patient sustained an injury to the long thoracic nerve, which supplies the serratus anterior. Branches of C5 and C6 enter the scalenus medius, unite in the muscle, and emerge as a single trunk and pass down the axilla. On the surface of the serratus anterior, the long thoracic nerve is joined by the branch from C7 and descends in front of the serratus anterior, providing segmental innervation to the serratus anterior.

The major determinant of ALS (Lou Gehrig disease) is progressive loss of motor neurons. The loss usually begins in one area, is asymmetrical, and later becomes evident in other areas. The first signs of ALS may include either upper or lower motor neuron loss. Recognition of upper motor neuron involvement depends on clinical signs, but electromyography and nerve conduction velocity studies can help identify lower motor neuron involvement. Electrodiagnostic abnormalities in three or more areas are required to make a definitive diagnosis. The motor unit potentials (MUPs) changes in ALS include impaired MUPs recruitment, unstable MUPs, and abnormal MUPs size and configuration. A number of abnormal spontaneous discharges can occur with ALS, especially fibrillation potentials and fasciculation potentials. In ALS, the motor nerve conduction study will be abnormal, but a co-existing normal sensory study is definitive for this disease. de Carvalho M, Johnsen B, Fuglsang-Frederiksen A: Medical technology assessment: Electrodiagnosis in motor neuron diseases and amyotrophic lateral sclerosis. Neurophysiol Clin 2001;31:341-348. Daube JR: Electrodiagnostic studies in amyotrophic lateral sclerosis and other motor neuron disorders. Muscle Nerve 2000;23:1488-1502.

Rehabilitation of the quadriceps muscle following a partial tear of the PCL has been associated with a favorable outcome. The quadriceps acts an antagonist to the PCL because its contraction results in anterior tibial translation, which reduces the tensile stress on the injured ligament. Strengthening of the hamstring musculature increases posterior tibial translation and is contraindicated during the early rehabilitative phase following a PCL injury. Brace use has not been found to significantly alter the outcome following nonsurgical management of PCL tears. Parolie JM, Bergfeld JA: Long-term results of nonoperative treatment of isolated posterior cruciate ligament injuries in the athlete. Am J Sports Med 1986;14:35-38.

Because the patient's thoracolumbar scoliosis is of a large enough magnitude, observation or bracing is not recommended. The thoracolumbar curve is flexible enough and L4 corrects well enough to the pelvis to consider anterior spinal fusion from T10 to L4. Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 161-171. Turi M, Johnston CE II, Richards BS: Anterior correction of idiopathic scoliosis using TSRH instrumentation. Spine 1993;18:417-422.

Osteosarcoma is the most common primary malignant tumor of bone in childhood, followed by Ewing's sarcoma. Rhabdomyosarcoma is a soft-tissue sarcoma of childhood. Chondrosarcoma rarely occurs in childhood. Osteochondromas are benign tumors of the bone. Simon M, Springfield D, et al: Osteogenic Sarcoma: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, p 226.

The radiograph reveals a distal clavicle fracture. In children, a periosteal sleeve will remain attached to the intact coracoclavicular ligament, and as such, remodeling can be expected. Therefore, nonsurgical management with a sling is preferred. Surgical treatment is not necessary, and a shoulder spica cast offers no advantage over a simple sling.

The child has a trigger thumb deformity. A trigger thumb is a developmental mechanical problem rather than a congenital deformity. The anomaly generally is not noted at birth. A fixed flexion deformity of the IP joint of the thumb most commonly occurs in children in the first 2 years of life. A stretching and splinting program may correct the deformity in the first year of life, but nonsurgical management after age 3 years results in a success rate of only 50%. Release of the proximal annular pulley of the flexor sheath is recommended at this age. Tan AH, Lam KS, Lee EH: The treatment outcome of trigger thumb in children. J Pediatric Orthop B 2002;11:256-259. Slakey JB, Hennrikus WL: Acquired thumb flexion contracture in children: Congenital trigger thumb. J Bone Joint Surg Br 1996;78:481-483.

This radiolucent lesion with a "fallen leaf sign" is typical for a unicameral bone cyst(UBC). The most appropriate treatment is to allow the fracture to heal with clinical and radiographic observation. Curettage and bone grafting is not the best initial management for UBC. Wide resection is not indicated for UBC. The proximal humerus is the most common site for UBC. While staging studies consisting of MRI, bone scan, and CT of the chest are appropriate for lesions suspected of being malignant, the classical appearance of this UBC is such that this work-up is not necessary initially. Following fracture healing, aspiration and injection of the cyst may be indicated. Dormans JP, Pill SG: Fractures through bone cysts: Unicameral bone cysts, aneurysmal bone cysts, fibrous cortical defects, and nonossifying fibromas. Instr Course Lect 2002;51:457-467.

Tuberculosis is uncommon in the cervical spine but has a relatively greater incidence in young children. In a review of 40 patients with lower cervical spine involvement (C2 to C7), 24 were younger than age 10 years at presentation. In children, the disease is characterized by more extensive involvement with the formation of large abscesses. In older patients with lower cervical tuberculosis, the disease is more localized but is more likely to cause paraplegia. Four-drug antituberculosis therapy should be used. For patients with pain or neurologic dysfunction, anterior excision of diseased bone and grafting are indicated. Whether vertebral body excision and grafting should be done in an asymptomatic 10-year-old child is debatable. The CT scan shows a large "cold" abscess that is partially calcified. Hsu LC, Leong JC: Tuberculosis of the lower cervical spine (C2 to C7): A report on 40 cases. J Bone Joint Surg Br 1984;66:1-5.

This child has the potential to walk and therefore should have all the contracted structures in the feet released as necessary to place the feet in a plantigrade position for fitting of ankle-foot orthoses. Physical therapy, manipulation, and casting may provide some benefit in a newborn with flexible feet but are not effective in an older infant with rigid clubfeet. Botulinum injections and tendon transfers are of no use because there are no muscles functioning below the knee. Tendon releases are more effective than tendon transfers in children with myelomeningocele. Mazur JM: Management of foot and ankle deformities in the ambulatory child with myelomeningocele, in Sarwark JR, Lubicky JP (eds): Caring for the Child with Spina Bifida. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2001, pp 155-160.

The two sesamoids of the metatarsophalangeal joint are embedded in the tendons of the short flexor of the great toe. They are held together by the intersesamoid ligament and the plantar plate, which inserts on the base of the proximal phalanx of the hallux. The flexor hallucis longus tendon inserts onto the distal phalanx of the great toe. The plantar calcaneonavicular (spring) ligament, by supporting the head of the talus, principally maintains the arch of the foot. The plantar fascia inserts distally onto the skin and to the flexor tendons and transverse metatarsal ligaments at each metatarsophalangeal joint. The intermetatarsal ligament attaches to the base of the second through fifth metatarsals. Lewis WH (ed): Gray's Anatomy of the Human Body, ed 20. Philadelphia, PA, Lea & Febiger, 2000.

The lateral calcaneal nerve is a branch of the sural nerve that runs along the lateral border of the Achilles tendon to innervate the lateral heel pad. Ankle arthroscopy involves posterior portals that hug the Achilles tendon to avoid the main trunks of the sural nerve and tibial nerve; however, the lateral calcaneal branch remains potentially vulnerable. The first branch of the lateral plantar nerve is actually a medial structure that partially innervates the plantar fascia and the abductor digiti quinti. The deep peroneal nerve is anterior to the ankle. Sitler DF, Amendola A, Bailey CS, et al: Posterior ankle arthroscopy: An anatomic study. J Bone Joint Surg Am 2002;84:763-769.

With the arm in the abducted, externally rotated position, the anterior band of the inferior glenohumeral ligament complex moves anteriorly, preventing anterior humeral head translation. Both the coracohumeral ligament and the superior glenohumeral ligament restrain the humeral head to inferior translation of the adducted arm, and to external rotation in the adducted position. The middle glenohumeral ligament is a primary stabilizer to anterior translation with the arm abducted to 45 degrees. The posterior band of the inferior glenohumeral ligament complex resists posterior translation of the humeral head when the arm is internally rotated. Harryman DT II, Sidles JA, Harris SL, et al: The role of the rotator interval capsule in passive motion and stability of the shoulder. J Bone Joint Surg Am 1992;74:53-66.

The MRI scan reveals an abnormal signal in the trapezoid, which lies adjacent to the capitate in the distal carpal row. The tumor is a giant cell tumor of bone. Cooney WP, Linscheid RL, Dobyns JH: The Wrist: Diagnosis and Operative Treatment. St Louis, MO, Mosby-Year Book, 1998, vol 1, pp 278-282. Green DP, Hotchkiss RN, Pederson WC (eds): Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, pp 2238-2240. bar based on these measurements is shown in Figure 54d. Initial treatment should consist of 1- bony bar resection and distal fibula epiphysiodesis. 2- bony bar resection and corrective osteotomy. 3- bony bar resection and physiodesis of the opposite distal tibial physis. 4- corrective osteotomy and a limb-lengthening procedure. 5- corrective osteotomy and physiodesis of the opposite distal tibial physis. 2 54a 54b 54c 54d Mapping of a physeal bar from biplane polytomography or CT helps to identify lesions that should be treated surgically and aids in planning the surgical approach and resection. Criteria for surgical excision are at least 2 years of longitudinal growth remaining and involvement of no more than 50% of the physis. Osteotomy is required if angular deformity is greater than 20 degrees. Although this physeal bar is large, it is slightly less than 50% of the total area of the physis. Limb lengthening in this case should be reserved for failure of bar resection. Physiodesis of the opposite distal tibia at this age would result in disproportionate shortening of both tibiae. Carlson WO, Wenger DR: A mapping method to prepare for surgical excision of a partial physeal arrest. J Pediatr Orthop 1984;4:232-238.

When managing a complex intra-articular fracture, it is imperative that there is adequate visualization of the joint; this usually means an extensile approach. At the elbow, this is usually through a transolecranon osteotomy. The recent addition of a muscle-sparing approach as described by Bryan and Morrey has gained popularity, but it is difficult to maintain soft-tissue viability and it may put the ulnar nerve at risk. A triceps-splitting approach, which can be used for simple single articular splits into the joint where extra-articular reduction is available, is possible and good results have been reported. To date, there is minimal data on these alternative approaches for comminuted intra-articular distal humeral fractures. McKee MD, Mehne DK, Jupiter JP: Fractures of the distal humerus: Part II, in Browner BD, Jupiter JP, Levine AM, Trafton P (eds): Skeletal Trauma, ed 2. Philadelphia, PA, WB Saunders, 1998, pp 1483-1522 McKee MD, Wilson TL, Winston L, Schemitsch EH, Richards RR: Functional outcome following surgical treatment of intra-articular distal humeral fractures through a posterior approach. J Bone Joint Surg Am 2000;82:1701-1707. Patterson SD, Bain GI, Mehta JA: Surgical approaches to the elbow. Clin Orthop 2000;370:19-33.

The radiographs show an eccentric metaphyseal lesion with a well-defined reactive rim of bone that is consistent with a nonossifying fibroma. Pathologic fractures through benign lesions should be treated as appropriate for the fracture, allowing the fracture to heal. Biopsy is not needed when the radiographic diagnosis is benign. MRI, in the presence of a fracture, is not particularly helpful because of the hematoma. If radiographic findings reveal that the lesion appears aggressive, a biopsy should be performed, obtaining tissue away from the fracture site. Marks KE, Bauer TW: Fibrous tumors of bone. Orthop Clin North Am 1989;20:377.

Sural nerve entrapment is the major risk of percutaneous repair. A small mini-open technique with a suture guide can obviate that issue. Re-rupture rates after surgical repair are approximately 3%. Infection and wound problems are rarely encountered with percutaneous repair; they are issues with open repair. Aracil J, Pina A, Lozano JA, et al: Percutaneous suture of Achilles tendon ruptures. Foot Ankle 1992;13:350-351. Sutherland A, Maffulli N: A modified technique of percutaneous repair of the ruptured Achilles tendon. Oper Orthop Traumatol 1998;10:50-58.

In the normal adult, the distance between the basion and the tip of the dens is 4 mm to 5 mm. Any distance greater than 5 mm is considered abnormal. This is one way to detect occipitocervical dissociation other than using the Power's ratio, which relies on an anterior dislocation. Wiesel SW, Rothman RH: Occipitoatlantal hypermobility. Spine 1979;4:187-191.

Although all of the above displaced injuries require reduction, the sacroiliac joint dislocation is a ligamentous injury. Without fixation, healing is unlikely and the result will be a painful dislocation. Both Holdsworth and Tile showed that the sacroiliac joint must be reduced anatomically and stabilized. The injuries through bone will unite fairly rapidly and, if reduced and stabilized with traction or external fixation, will generally result in an acceptable outcome unless modified by other associated problems such as neurologic injury. Tile M: Fractures of the Pelvis and the Acetabulum. Baltimore, MD, Williams and Wilkins, 1995. Holdsworth F W: Dislocation and fracture dislocation of the pelvis. J Bone Joint Surg Br 1948;30:461-465.

The findings are consistent with an aneurysmal bone cyst. The MRI scan demonstrates a lesion involving the posterior elements of the vertebrae with fluid-fluid levels and neural compression. Fibrovascular tissue with multinucleated giant cells surrounding a vascular lake is seen on the histology. The most appropriate treatment is a marginal resection of the involved posterior elements. Although the recurrence rate can be as high as 25% to 30%, wide surgical resection could result in permanent neurologic injury and is not necessary. Aspiration and steroid injection have been advocated but would not relieve the nerve compression in this patient. Radiation therapy and chemotherapy are not indicated. Mankin HJ, Hornicek FJ, Ortiz-Cruz E, et al: Aneurysmal bone cyst: A review of 150 patients. J Clin Oncol 2005;23:6756-6762.

The initial stages of posterior tibial tendon insufficiency, where the deformity remains supple, may be treated with bracing or an orthotic for pain relief. The Arizona brace was introduced in 1988, and assists in pain relief and deformity correction by minimizing hindfoot valgus alignment, lateral calcaneal displacement, and medial ankle collapse. It is particularly helpful in those patients with advanced disease that cannot tolerate an ankle-foot orthosis. All other choices are incorrect because of the addition of lateral posting, which is not advantageous in valgus deformities. The addition of medial posting to any of the above choices would render them correct alternatives. A heel lift is applicable in Achilles tendon disorders, not posterior tibial tendon disorders. Chao W, Wapner KL, Lee TH, et al: Nonoperative management of posterior tibial tendon dysfunction. Foot Ankle Int 1996;17:736-741.

The radiographs show Ficat and Arlet stage 2 osteonecrosis. The femoral head remains round, and there are sclerotic changes in the superolateral quadrant. Patients with systemic lupus erythematosus are at risk for osteonecrosis because of prednisone use and the underlying metabolic changes associated with the condition (hypofibrinolysis and thrombophilia). MRI is the best diagnostic method for detecting osteonecrosis, with a greater than 98% sensitivity and specificity. For this patient, an MRI can assess the contralateral hip for any involvement and can quantify the extent of the lesion. Mont MA, Jones LC, Sotereanos DG, Amstutz HC, Hungerford DS: Understanding and treating osteonecrosis of the femoral head. Instr Course Lect 2000;49:169-185.

Based on the MR arthrogram in which gadolinium (bright on T1-weighted images) was injected into the joint space prior to imaging, the study shows a tear of the anterior band of the ulnar collateral ligament (UCL). The disruption in the distal end of the UCL is outlined by contrast. A small collection of contrast extravasation into the flexor musculature further confirms the presence of a tear. The UCL has a broad-based attachment on the medial epicondyle and has a pointed or tapered attachment distally on the ulna. Most UCL tears occur distally at the ulnar (coronoid) attachment. MR arthrography provides improved sensitivity compared to conventional MRI, without contrast, for the detection of UCL pathology, particularly in the subacute or chronic setting. After the soft-tissue edema and joint fluid associated with the injury have resolved, the torn end of the ligament may lie in contact with its adjacent attachment and create a false-negative appearance. In this patient, a noncontrasted MR arthrogram showed no tear, yet the tear is apparent with intra-articular contrast and distention. MR arthrography of the elbow also may be useful in detecting intra-articular bodies or in evaluation for loose osteochondral fragments or flaps. Morrey BF: Acute and chronic instability of the elbow. J Am Acad Orthop Surg 1996;4:117-128.

The MRI scan shows a far lateral disk herniation. With the L4-5 disk, a far lateral herniation abuts the left L4 nerve root. The findings would be consistent with those of a left L4 radiculopathy and would include pain or a sensory deficit on the anteromedial aspect of the knee, diminished patellar tendon reflex, and quadriceps weakness, perhaps making it difficult to walk up and down stairs. Fardin DF, Garfin SR (eds): Orthopaedic Knowledge Update: Spine 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 329.

Anatomic studies have shown that the thickest bone of the occiput is at the level of the external occipital protuberance. It ranges from 11.5 mm to 15.1 mm in men and from 9.7 mm to 12 mm in women. In general, the bone thins as it extends distally from the external occipital protuberance and it also moves laterally from the midline. The structures at risk during screw placement include the venous sinuses. Nadim Y, Lu J, Sabry FF, et al: Occipital screws in occipitocervical fusion and their relation to the venous sinuses: An anatomic and radiographic study. Orthopedics 2000;23:717-719.

The patient has snapping hip syndrome of the internal type, which is more common in ballet dancers. It is caused by the iliopsoas tendon gliding over the iliopectineal line or the femoral head. The diagnosis usually can be made by the history and physical examination. Snapping is reproduced by hip flexion and extension or flexion with external rotation and abduction. Conventional and dynamic ultrasonography will confirm the snapping structure. Radiographs occasionally show calcifications near the lesser trochanter. MRI can be used to rule out other diagnoses that can simulate snapping hip. Gruen GS, Scioscia TN, Lowenstein JE: The surgical treatment of internal snapping hip. Am J Sports Med 2002;30:607-613.

The size of the rotator cuff tear in both anteroposterior and mediolateral dimensions has been found to correlate best with outcome. Older patient age and rupture of the long head of the biceps tend to be associated with larger tears and, therefore, may be associated indirectly with a poorer outcome. Iannotti JP: Full-thickness rotator cuff tears: Factors affecting surgical outcome. J Am Acad Orthop Surg 1994;2:87-95.

Improvement in the appearance of the hip joint on functional radiographic evaluation (abduction/adduction views) has been shown to be predictive of outcome following joint preserving surgery. CT and MRI findings have not been shown to be predictive of outcome.

The patient has primary scapulotrapezius winging caused by surgical damage to the spinal accessory nerve during a lymph node biopsy. Other causes include blunt trauma, traction, and penetrating injuries. With spinal accessory palsy, the shoulder appears depressed and laterally translated because of unopposed serratus anterior muscle function. With primary serratus anterior winging that is the result of long thoracic nerve palsy, the scapula assumes a position of elevation and medial translation with the inferior angle rotated medially. The thoracodorsal nerve innervates the latissimus dorsi and is not associated with scapular winging. Kuhn JE, Plancher KD, Hawkins RJ: Scapular winging. J Am Acad Orthop Surg 1995;3:319-325.

Because the radiograph reveals an intermetatarsal angle of greater than 15 degrees and an incongruent metatarsophalangeal joint, the treatment of choice is a proximal first metatarsal osteotomy with distal soft-tissue realignment. A distal chevron procedure would not correct this degree of deformity. A Keller procedure is reserved for a less active elderly individual. Arthrodesis is appropriate for a patient with advanced arthritis of the metatarsophalangeal joint. The double osteotomy is reserved for the congruent metatarsophalangeal joint with hallux valgus. Coughlin MJ, Carlson RE: Treatment of hallux valgus with an increased distal metatarsal articular angle: Evaluation of double and triple first ray osteotomies. Foot Ankle Int 1999;20:762-770.

Because the patient has a transverse midshaft fracture with no evidence of comminution, the treatment of choice is closed reduction and stabilization with flexible intramedullary nails. Transverse fractures treated with an external fixator heal with poor callus and have a high refracture rate. In addition, the pin tracks produce undesirable and excessive scarring. Femoral pin traction is safe and effective but results in considerable muscle wasting and a slow return to function. Interlocking nails run the risk of greater trochanteric growth disturbance and/or osteonecrosis of the femoral head in this age group. Plate fixation, while effective, requires considerable tissue dissection with large scar formation. It also requires a rather extensive dissection for later plate removal. Ligier JN, Metaizeau JP, Prevot J, Lascombes P: Elastic stable intramedullary nailing of femoral shaft fractures in children. J Bone Joint Surg Br 1988;70:74-77.

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.

Patella baja is commonly encountered when converting a high tibial osteotomy (HTO) to a TKA. Patella baja most likely occurs because of scarring. Meding and associates' study did not show an increased rate of lateral release when converting a knee that had undergone a previous HTO. Yoshino N, Shinro T: Total knee arthroplasty after failed high tibial osteotomy, in Callaghan JJ, Rosenberg AG, Rubash HE, et al (eds): The Adult Knee. Philadelphia, PA, JB Lippincott, 2003, vol 2, pp 1265-1271.

Nonbloody effusions that are greater than 1 mL are readily detected by MRI. They appear black on T1-weighted images and white on T2-weighted images. A sanguinous effusion is seen as white on T1-weighted images and black on T2-weighted images. Resnick D, Kang HS: Synovial joints, in Resnick D, Kang HS (eds): Internal Derangements of Joints: Emphasis on MR Imaging. Philadelphia, PA, WB Saunders, 1997, pp 49-53.

The radiograph reveals an atrophic nonunion of the diaphysis of the clavicle. Electrical or ultrasound stimulation may be an option in diaphyseal nonunions that have shown some healing response with callus formation, but these techniques are not successful in an atrophic nonunion. The preferred technique for achieving union is open reduction and internal fixation with bone graft. Percutaneous fixation has no role in treatment of nonunions of the clavicle. Boyer MI, Axelrod TS: Atrophic nonunion of the clavicle: Treatment by compression plating, lag-screw fixation and bone graft. J Bone Joint Surg Br 1997;79:301-303.

Developmental dysplasia of the hip (DDH) leads to early arthritis of the hip as seen in this patient. Although DDH is believed to mostly affect the acetabulum, most patients with DDH also have anatomic aberrations of the femur. Using three-dimensional computer models generated by reconstruction of CT scans, dysplastic femurs were shown to have shorter necks and smaller, straighter canals than the controls. The shape of the canal became more abnormal with increasing subluxation. The studies also have shown that the primary deformity of the dysplastic femur is rotational, with an increase in anteversion of 5 degrees to 16 degrees, depending on the degree of subluxation of the hip. The rotational deformity of the dysplastic femur arises within the diaphysis between the lesser trochanter and the isthmus and is not attributable to a torsional deformity of the metaphysis. Osteopenia is not a concern in a patient with an excellent cortical index (thick cortices and narrow canal). Femoral varus or bowing of the femur is not a typical finding in patients with DDH. Noble PC, Kamaric E, Sugano N, et al: Three-dimensional shape of the dysplastic femur: Implications for THR. Clin Orthop 2003;417:27-40.

Engh and associates reported on the results of 63 knees (56 patients) following polyethylene exchange. The mean interval between exchange and the index total knee arthroplasty was 59 months. The mean follow-up after exchange was 7.4 years. Seven of 48 knees with adequate follow-up failed. Greater failure occurred if there was more severe wear before the exchange. Greater undersurface wear also resulted in a higher failure rate. Perioperative osteolysis or intraoperative observation of metallosis did not have an impact on the failure of polyethylene exchange. The risk of infection is no different from other total knee arthroplasty revisions. Wasielewski RC, Parks N, Williams I, et al: Tibial insert undersurface as a contributing source of polyethylene wear debris. Clin Orthop 1997;345:53-59.

The spleen is the most common organ injured in the abdomen as the result of blunt trauma. It is also the most common cause of death because of an abdominal injury. The liver is the second most commonly injured organ. Injury to the other organs is rare. The diagnosis can be made with CT. Treatment ranges from observation to splenectomy, depending on the severity of injury. Green GA: Gastrointestinal disorders in the athlete. Clin Sports Med 1992;11:453-470.

The patient has chronic posterolateral instability with a varus knee alignment; therefore, the most effective treatment is a valgus-producing HTO. A repeat soft-tissue reconstruction without correction of the varus alignment will most likely fail. An ACL reconstruction is not indicated with a normal Lachman's test. Physical therapy and bracing will have little effect. Naudie DD, Amendola A, Fowler PJ: Opening wedge high tibial osteotomy for symptomatic hyperextension-varus thrust. Am J Sports Med 2004;32:60-70.

The median nerve passes through the pronator teres and deep to the flexor digitorum superficialis. The ulnar artery passes deep to both. Anderson JE (ed): Grant's Atlas of Anatomy, ed 7. Baltimore, MD, Williams and Wilkins, 1978, pp 6-55.

The adult menisci are considered to be relatively avascular structures, with the peripheral blood supply originating predominately from the lateral and medial genicular arteries. Branches of these vessels form the perimeniscal capillary plexus, which supplies the peripheral border throughout its attachment to the joint capsule. Vascular penetration studies have shown that 10% to 30% of the peripheral portion of the medial meniscus and 10% to 25% of the lateral meniscus are vascularized. Arnoczky SP, Warren RF: Microvasculature of the human meniscus. Am J Sports Med 1982;10:90-95.

The MRI scan reveals a lobular mass that is below the vitamin E tablet marker taped to the skin. This is juxtaposed to the tibialis anterior tendon. It is slightly more enhanced than the surrounding subcutaneous fat and is consistent with a ganglion. Osteosarcoma, aneurysmal bone cyst, or unicameral bone cyst all would demonstrate enhancement or pathology in the bone. This is clearly a well-defined soft-tissue mass. Gouty tophi show low to intermediate signal on T1- and T2-weighted images. Kransdorf MJ, Jelinek JS, Moser RP Jr, et al: Soft tissue masses: Diagnosis using MR imaging. Am J Roentgenol 1989;153:541-547. Wetzel LH, Levine E: Soft-tissue tumors of the foot: Value of MR imaging for specific diagnosis. Am J Roentgenol 1990;155:1025-1030.

The patient has a midstem periprosthetic fracture, which commonly results in loosening of the prosthesis. Patients who have a large amount of bone loss may require an allograft with the surgical reconstruction. Although the patient reported a fall, her history is also consistent with preexisting loosening of the prosthesis. Chronic infection has been shown in up to 16% of these fractures; however, the patient's work-up revealed no infection. Garbuz DS, Masri BA, Duncan CP: Periprosthetic fractures of the femur: Principles of prevention and management, in Cannon WD Jr (ed): Instructional Course Lectures 47. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 237-242. Bethea JS III, DeAndrade JR, Fleming LL, Lindenbaum SD, Welch RB: Proximal femoral fractures following total hip arthroplasty. Clin Orthop 1982;170:95-106.

The sural nerve and its terminal branches course through the lateral hindfoot and midfoot area and are directly at risk in surgeries involving the peroneal tendon complex and the fifth metatarsal. The first branch of the lateral plantar nerve originates in the tarsal tunnel region and courses across the plantar heel area to innervate the abductor digiti minimi; it is not at direct risk with fifth metatarsal surgery. The saphenous, superficial peroneal, and deep peroneal nerves are not at risk anatomically with a lateral midfoot incision. Donley BG, McCollum MJ, Murphy GA, Richardson EG: Risk of sural nerve injury with intramedullary screw fixation of fifth metatarsal fractures: A cadaver study. Foot Ankle Int 1999;20:182-184.

The most likely diagnosis is transient synovitis. Initial management should consist of bed rest and serial observation to rule out atypical septic arthritis of the hip. In an unreliable family situation, hospitalization for bed rest and observation may be indicated. Other disorders such as proximal femoral osteomyelitis, leukemia, juvenile rheumatoid arthritis, pelvic osteomyelitis, diskitis, and arthralgia secondary to other inflammatory disorders should be considered. However, these disorders are unlikely because of the paucity of abnormal clinical signs exhibited by the patient. On the other hand, transient synovitis of the hip in children is a diagnosis of exclusion; other possibilities should be explored if the patient's symptoms do not follow a typical course and resolve in 4 to 21 days.

The patient is a young laborer with osteoarthritis. Initial treatment should begin with nonsurgical management that may include anti-inflammatory drugs, cortisone injections, and physical therapy to diminish pain and improve motion. The other choices may eventually be necessary but should only follow a course of nonsurgical management. Norris TR (ed): Orthopaedic Knowledge Update: Shoulder and Elbow 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 257-266.

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 CT scan reveals a completely displaced physeal fracture of the medial clavicle with marked posterior displacement of the distal fragment. This fracture pattern is associated with potential injury to the vascular structures of the mediastinum. Reduction should be performed for this fracture and generally can be done closed with shoulder retraction and upward pull on the clavicle with a towel clip. Once reduced, the fracture is relatively stable and typically will heal in good position. Reduction should be performed in the operating room in the event that a vascular injury is detected once compression is removed from the clavicle. Open reduction may be necessary if closed reduction is not possible; however, pinning or ligament reconstruction usually is not necessary. Rockwood CA, Matsen FA (eds): The Shoulder, ed 2. Philadelphia, PA, WB Saunders, 1998, p 581.

The on-field evaluation and management of a seriously injured athlete requires that health care teams have a game plan in place and proper equipment that is readily available. The initial step, which consists of stabilizing the head and neck by manually holding them in a neutral position, is then followed by assessment of breathing, pulses, and level of consciousness. If the athlete is breathing, management should consist of mouth guard removal and airway maintenance. If the athlete is not breathing, the face mask should be removed, with the chin strap left in place. The airway must be established, followed by initiation of assisted breathing. CPR is instituted only when breathing and circulation are compromised. In the unconscious athlete or if a cervical spine injury is suspected, the helmet must not be removed until the athlete has been transported to an appropriate facility and the cervical spine has been completely evaluated. McSwain NE, Garnelli, RL: Helmet removal from injured patients. Bull of Am Coll Surg 1997;82:42-44.

The majority of large collagen fibers within the menisci are oriented circumferentially. It is these fibers that develop the hoop stress with compressive loading of the menisci. Most meniscal tears are longitudinal and occur between these circumferential fibers. Mow VC, et al: Structure and function relationships of the menisci of the knee, in Mow VC, Arnoczky SP, Jackson DW (eds): Knee Meniscus: Basic and Clinical Foundations. New York, NY, Raven Press, 1992, pp 37-57.

Spontaneous subluxation of the sternoclavicular joint occurs without any significant trauma. It is usually accentuated by placing the extremity in an overhead position. Discomfort usually resolves within 4 to 6 weeks with nonsurgical management. Rockwood CA, Wirth MA: Disorders of the sternoclavicular joint, in Rockwood CA, Matsen FA, Wirth MA, et al (eds): The Shoulder. Philadelphia, PA, WB Saunders, 2004, vol 2, pp 1078-1079.

Avulsion fractures of the medial epicondyle are caused by a valgus stress applied to the immature elbow and usually occur in children between the ages of 9 and 14 years. Long-term studies have shown that isolated fractures of the medial epicondyle with between 5 to 15 mm of displacement heal well. Brief immobilization (1 to 2 weeks) in a long arm cast or splint yields results similar to open reduction and internal fixation. Fibrous union of the fragment is not associated with significant symptoms or diminished function. Surgical excision of the fragment yielded the worst results in one study and should be avoided. Open reduction is best reserved for those injuries in which the medial epicondylar fragment becomes entrapped in the elbow joint during reduction and cannot be extracted by closed manipulation. Farsetti P, Potenza V, Caterini R, Ippolito E: Long-term results of treatment of fractures of the medial humeral epicondyle in children. J Bone Joint Surg Am 2001;83:1299-1305.

This patient has shoulder laxity without apprehension. Because there is a wide range of normal laxity in asymptomatic shoulders, the physician should inform the student of these findings, recommend shoulder strengthening exercises, and allow unrestricted sports participation unless symptoms develop. Harryman DT, Sidles JA, Harris SL, Matsen FA III: Laxity of the normal glenohumeral joint: A quantitative in vivo assessment. J Shoulder Elbow Surg 1992;1:66-76. Hawkins RJ, Bokor RJ: Clinical evaluation of shoulder problems, in Rockwood CA Jr, Matsen FA III (eds): The Shoulder. Philadelphia, PA, WB Saunders, 1998, vol 1, p 186. McFarland EG, Campbell G, McDowell J: Posterior shoulder laxity in asymptomatic athletes. Am J Sports Med 1996;24:468-471.

The plain radiographs show a horizontal orientation of the C5 facet joint. The CT scan through C5 reveals an ipsilateral pedicle and lamina fracture (floating facet). This injury involves two adjacent motion segments and is extremely unstable. Lateral mass plates, with or without the purchase of the "floating facet," provide the best means of stabilization and should include the facet above (C4) and below (C6) the level of injury. Orthotic immobilization is insufficient for this particular injury. Halo vest treatment does not control the subaxial spine well and is of limited value. While simple midline (Rogers) wiring provides some tension band restoration, it is not optimal for rotational control. The use of lateral mass plates provides rotational stability. Another option would be anterior fusion and plating, which would save cervical segments. Levine AM, Mazel C, Roy-Camille R: Management of fracture separations of the articular mass using posterior cervical plating. Spine 1992;17:S447-S454. Levine AM: Facet fractures and dislocations, in Levine AM, Eismont FJ, Garfin S, Zigler JE (eds): Spine Trauma. Philadelphia, PA, WB Saunders, 1998, pp 360-362. Whitehill R, Richman JA, Glaser JA: Failure of immobilization of the cervical spine by the halo vest: A report of five cases. J Bone Joint Surg Am 1986;68:326-332.

From birth until the age of 4 years, the primary blood supply to the femoral head is from the medial and lateral circumflex arteries that traverse the femoral neck. After the age of 4 years, the contribution of the lateral femoral circumflex artery, which traverses the anterior portion of the femoral neck, becomes negligible. The posterosuperior and posteroinferior retinacular vessels, branches of the medial femoral circumflex artery, become the primary blood supply to the epiphysis. The contribution of the artery of the ligamentum teres is minimal after the age of 4 years. Hughes LO, Beaty JH: Fractures of the head and neck of the femur in children. J Bone Joint Surg Am 1994;76:283-292.

The most important consequence of a displaced talar neck fracture after closed or open treatment is malunion. Because displacement of the talar neck is associated with displacement of the subtalar joint, any malunion leads to intra-articular incongruity or malalignment of the subtalar joint. Varus malunion is common when there is comminution of the medial talar neck. This results in pain, osteoarthritis, and hindfoot deformity that requires further treatment. Because of these complications, it is imperative that all displaced talar neck fractures are reduced anatomically; fragmented fractures may require bone grafting to maintain the length and rotation of the neck. Tile M: Fractures of the talus, in Schatzker J, Tile M (eds): Rationale of Operative Fracture Care, ed 2. Berlin, Springer-Verlag, 1996, pp 563-588. Daniels TR, Smith JW, Ross TI: Varus malalignment of the talar neck: Its effect on the position of the foot and on subtalar motion. J Bone Joint Surg Am 1996;78:1559-1567.

The stiffness is most influenced by the geometry, in particular the diameter of the stem. The bending rigidity increases to the fourth power of the radius. The elastic modulus of the material increases as a direct linear relationship. The surface coating does not affect the bending rigidity greatly unless it increases the diameter significantly.

While guidelines for predicting fracture risk are at best imprecise, the scoring system by Mirels (pain, anatomic location, and pattern of bony destruction) has been shown to be most predictive of fracture risk. Functional pain, peritrochanteric location, and lytic bone destruction are the greatest risk factors for pathologic fracture. The factors of patient weight, age, soft-tissue mass, and location within bone are all of lesser importance. Frassica FJ, Frassica DA, McCarthy EF, Riley LH III: Metastatic bone disease: Evaluation, clinicopathologic features, biopsy, fracture risk, nonsurgical treatment, and supportive management. Instr Course Lect 2000;49:453-459.

The femoral construct shown in the radiograph has failed to produce ingrowth of the stem. The stem has subsided and rotated. Impingement of the trochanter did not occur until after the stem subsided. There is no evidence of osteolysis or third-body wear debris from the cerclage wire. A larger femoral stem needs to be implanted to achieve rigid fixation. Pelicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 217-238.

The axillary nerve lies within millimeters of the anterior inferior capsule. The inferior capsule is of varying thickness, and thermal energy used in shortening the ligament can cause damage to the sensory fibers of the axillary nerve. Clinically, this is manifested as a burnt skin sensation in the axillary nerve distribution area. The motor branch of the axillary nerve is usually spared. The suprascapular nerve and the radial nerve are far from the shrinkage zone. The musculocutaneous nerve, frequently at risk with open procedures, lies well anterior. Fanton GS: Arthroscopic electrothermal surgery of the shoulder. Op Tech Sports Med 1998;6:157-160.

It is not uncommon for patients with ankylosing spondylitis to sustain extension-type fractures, most typically of the cervicothoracic junction. These fractures can appear nondisplaced or minimally displaced initially, making them difficult to diagnose. Because there is no mobility between vertebrae, fractures tend to occur more like those of a transverse fracture of a long bone. In addition, the vertebral bodies are vascular and their canals are relatively enclosed, making them vulnerable to epidural bleeding. The MRI scan reveals an epidural hematoma located posteriorly on the cord; therefore, the treatment of choice is surgical evacuation and a posterior laminectomy. Because of the intrinsic instability of such fractures at the time of the laminectomy, internal fixation and stabilization with a posterior fusion is warranted. A simple laminectomy will only increase instability, and control is unlikely with halo vest immobilization. An anterior procedure will not effectively treat the problem given the location of the hematoma. Consideration can be given to methylprednisolone and observation; however, this will not eradicate the problem. Bohlman HH: Acute fractures and dislocations of the cervical spine. J Bone Joint Surg Am 1979;61:1119-1142.

Although pseudarthrosis can be found anywhere within the spine that has been fused using long multisegmental fixation to the sacrum, it most commonly occurs at the lumbosacral junction. The thoracolumbar junction is another common site of potential pseudarthrosis. In this location, the anatomy changes from lumbar transverse processes to thoracic through the transition zone, and overlying instrumentation often makes it difficult to obtain enough sound bone on decorticated bone to achieve a successful fusion. Saer EH III, Winter RB, Lonstein JE: Long scoliosis fusion to the sacrum in adults with nonparalytic scoliosis: An improved method. Spine 1990;15;650-653. Kostuik JP, Hall BB: Spinal fusions to the sacrum in adults with scoliosis. Spine 1983;8:489-500.

The patient has Ewing's sarcoma. Management options for local tumor control include radiation therapy, resection, or a combination; however, in this patient wide resection is preferred over radiation therapy. Radiation therapy is associated with damage to the growth plate, pathologic fracture, radiation-induced sarcomas, and a local recurrence rate of approximately 10% to 12%. Radiation therapy is used for positive margins, unresectable tumors, or for tumors that have a poor response to chemotherapy. Amputation is not necessary since the tumor is resectable. Chemotherapy has improved overall survival rates to over 60% of patients. Sailer SL: The role of radiation therapy in localized Ewing' sarcoma. Semin Radiat Oncol 1997;7:225-235. Shankar AG, Pinkerton CR, Atra A, Ashley S, Lewis I, Spooner D, et al: Local therapy and other factors influencing site of relapse in patients with localised Ewing's sarcoma. United Kingdom Children's Cancer Study Group (UKCCSG). Eur J Cancer 1999;35:1698-1704. Carrie C, Mascard E, Gomez F, Habrand JL, Alapetite C, Oberlin O, et al: Nonmetastatic pelvic Ewing sarcoma: Report of the French society of pediatric oncology. Med Pediatr Oncol 1999;33:444-449.

Unwitnessed spiral fractures should raise the possibility of child abuse, especially prior to walking age. With nonaccidental trauma being considered in the differential diagnosis, a skeletal survey is indicated to determine if there are other fractures in various stages of healing. Kempe CH, Silverman FN, Steele BF, et al: The battered-child syndrome. JAMA 1962;181:17-24.

Though anatomic variations exist, both divisions of the sciatic nerve most commonly pass between the piriformis and superior gemellus. This anatomic consideration is relevant during the posterior approach to the hip, where careful retraction of the rotators avoids sciatic nerve injury. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, pp 335-348.

The use of multiagent chemotherapy has been shown to be associated with a survival benefit in patients with osteosarcoma. The use of chemotherapy in adults with soft-tissue sarcoma remains somewhat controversial. It has not been associated with improved survival rates in patients with renal carcinoma, dedifferentiated chondrosarcoma, or melanoma. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 53.

A high index of suspicion is required to identify a possible navicular stress fracture, especially in runners. High pain tolerance in the competitive athlete and often minimal swelling contribute to frequent delays in diagnosis. Localized tenderness over the dorsal navicular (so-called "N spot") in a running athlete should alert the treating physician. In this patient, the radiographs are negative and the MRI scan shows marrow edema within the navicular. This could represent a stress reaction, stress fracture, or osteonecrosis. Appropriate management should include non-weight-bearing immobilization and obtaining a CT scan to determine if a fracture is present. Early surgical treatment may be considered but only if a fracture is identified. Lee A, Anderson R: Stress fractures of the tarsal navicular. Foot Ankle Clin 2004;9:85-104.

Collagen type X is produced only by hypertrophic chondrocytes during enchondral ossification (growth plate, fracture callus, heterotopic ossification) and is associated with calcification of cartilage in the deep zone of articular cartilage. Collagen type I is the predominant collagen in bone, ligament, and tendon. Collagen type II is the predominant collagen in articular cartilage. Proteoglycan aggrecan and hyaluronic acid are components of the extracellular matrix and are involved in the compressive strength characteristics of articular cartilage. Buckwalter JA, Mankin HJ: Articular cartilage: Tissue design and chondrocyte matrix interactions. Instr Course Lect 1998;47:477-486.

The patient has end-stage rotator cuff tear arthropathy. The radiograph shows complete proximal humeral migration (acromiohumeral interval of 0 mm), severe glenohumeral arthritis, and acetabularization of the acromion. In addition, she has "pseudoparalysis" with active elevation of only 30 degrees. Reverse shoulder arthroplasty affords her the best opportunity for pain relief and functional improvement. The other procedures have mixed results but typically are better for pain relief than they are for functional gains. 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.

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.

Multidirectional instability is a common finding in young female athletes. The anatomic structures are all intact but are hypermobile; therefore, CT and bone scans and scapular Y-views are often normal. Obtaining a weighted or AP stress view while applying downward traction on the arm will document instability and hypermobility of the joint. MRI generally is not indicated in this condition. Ultrasound is used primarily for rotator cuff pathology. Neer CS II, Foster CR: Inferior capsular shift for involuntary inferior and multidirectional instability of the shoulder: A preliminary report. J Bone Joint Surg Am 1980;62:897-908.

The phenomenon of tumors misdiagnosed as athletic injuries has been termed "sports tumors." Lewis and Reilly presented a series of 36 patients who initially were thought to have a sports-related injury but ultimately were diagnosed with a primary bone tumor, soft-tissue tumor, or tumor-like condition. Muscolo and associates presented a series of 25 tumors that had been previously treated with an intra-articular procedure as a result of a misdiagnosis of an athletic injury. Initial diagnoses included 21 meniscal lesions, one traumatic synovial cyst, one patellofemoral subluxation, one anterior cruciate ligament tear, and one case of nonspecific synovitis. The final diagnoses were a malignant tumor in 14 patients and a benign tumor in 11 patients. The authors noted that oncologic surgical treatment was affected in 15 of the 25 patients. The most frequent causes of erroneous diagnosis were initial poor quality radiographs and an unquestioned original diagnosis despite persistent symptoms. Persistent symptoms warrant further diagnostic studies, not additional treatment such as physical therapy, corticosteroid injection, or an unloader brace. Although a bone scan may be helpful in this case and confirm arthrosis of the medial compartment, the suspicion of a soft-tissue mass makes MRI the imaging modality of choice. Muscolo DL, Ayerza MA, Makino A, et al: Tumors about the knee misdiagnosed as athletic injuries. J Bone Joint Surg Am 2003;85:1209-1214.

The recurrent laryngeal nerve lies between the trachea and the esophagus. The vagus nerve lies in the carotid sheath. The sympathetic trunk lies anterior to the longus colli muscles. The hypoglossal and superior laryngeal nerves are both at risk during the exposure but are not located between the trachea and the esophagus. Flynn TB: Neurologic complications of anterior cervical interbody fusion. Spine 1982;7:536-539.

The patient has respiratory distress as manifested by his difficulty in lying flat. In addition, the diaphoresis and the change in his voice indicate retropharyngeal edema or hematoma that is compressing his larynx. The only appropriate treatment is hospital admission and elective intubation. During intubation it is possible to cause laryngospasm in a patient with a hyperacute airway; therefore, the surgeon should be prepared to perform a cricothyroidotomy. Often a fiberoptically guided intubation is the only way to find the airway in the presence of retropharyngeal edema or hematoma. Emery SE, Smith MD, Bohlman HH: Upper-airway obstruction after multilevel cervical corpectomy for myelopathy. J Bone Joint Surg Am 1991;73:544-551.

Despite the negative radiographic findings, the child's age and presentation are most consistent with a toddler's fracture. There is often not a witnessed injury. The differential diagnosis of infection is unlikely given that the child is afebrile and shows no signs of illness. Immobilization will make the child more comfortable and will often allow weight bearing. Repeat radiographs at the end of treatment will show a healing fracture and confirm the diagnosis. Aspiration of the tibial metaphysis would be indicated to obtain material for culture. The bone scan and MRI would show abnormalities, but these studies are nonspecific, costly, and time-consuming. Occasionally, oblique radiographs will show the fracture. Halsey MF, Finzel KC, Carrion WV, Haralabatos SS, et al: Toddler's fracture: Presumptive diagnosis and treatment. J Pediatr Orthop 2001;21:152-156.

The patient's history, including the timing and type of symptoms, is typical for postoperative diskitis. The elevated ESR, 5 weeks after surgery, is also consistent with infection; a normal WBC count is not unusual. Management should consist of MRI with gadolinium; if positive, this should be followed by percutaneous biopsy to confirm the organism. Open biopsy may be considered if the percutaneous biopsy is unsuccessful. Anterior debridement and interbody fusion is reserved for the occasional patient that fails to respond to intravenous antibiotics, bed rest, and immobilization. Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 257-271.

Adult articular cartilage has less than 5% of the synthesis rate of type II collagen than that seen in developing teenagers. Both synthesis and degradation of type II collagen in normal adult articular cartilage is very low compared to children. In osteoarthrosis, both synthesis and degradation are increased, but the collagen does not properly incorporate into the matrix. Lippiello L, Hall D, Mankin HJ: Collagen synthesis in normal and osteoarthritic human cartilage. J Clin Invest 1977;59:593-600.

Following repair of a displaced intra-articular distal humerus fracture, the ability to regain full elbow range of motion is rare. Recent reports of olecranon osteotomy have yielded healing rates of between 95% to 100%. According to McKee and associates, patients can be expected to have residual loss of elbow flexion strength of 25%. McKee MD, Wilson TL, Winston L, et al: Functional outcome following surgical treatment of intra-articular distal humeral fractures through a posterior approach. J Bone Joint Surg Am 2000;82:1701-1707.

The patient has a transscaphoid dorsal perilunate dislocation. The radiographs clearly define a dorsal dislocation of the capitolunate joint, and the scaphoid fracture component is easily visible on the AP view. A scaphoid fracture alone is an unlikely diagnosis because of the midcarpal dislocation component. The radiocarpal joint is not dislocated because the lunate is sitting in the lunate fossa of the radius. Isolated radiocarpal dislocations are not associated with a midcarpal disruption. While a midcarpal dislocation is a component of a dorsal perilunate dislocation, this diagnosis does not address the scaphoid fracture. A volar lunate dislocation is not seen because the lunate is reduced in the lunate fossa of the distal radius. Volar lunate dislocations are in the spectrum of injury of perilunate dislocations and fracture-dislocations; however, the radiographs show a transscaphoid dorsal perilunate dislocation. Mayfield JK, Johnson RP, Kilcoyne RK: Carpal dislocations: Pathomechanics and progressive perilunar instability. J Hand Surg Am 1980;5:226-241.

The patient has a large zone of osteonecrosis of the left femoral head. The wedge-shaped zone of decreased signal intensity on the T1 image in the subchondral region of the femoral head is typical. Based on these findings, total hip arthroplasty is the most appropriate treatment. Open reduction and internal fixation will not help this condition. Incisional biopsy is indicated only if the MRI scan shows a probable neoplasm. Resection of the proximal femur is indicated only for aggressive malignancy. Arthrodesis may be considered in a younger patient but not in a 68-year-old individual. Other treatments, not listed, such as core decompression, vascularized fibular transplant, and osteotomy may be options in selected patients. Urbaniak JR, Jones JP Jr (eds): Osteonecrosis: Etiology, Diagnosis, and Treatment. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 213-223.

The most common benign bone tumors in childhood are discovered incidentally and include single bone cysts, fibrous cortical defects, nonossifying fibroma, and osteochondroma. Benign bone tumors can be classified as latent, active, or aggressive. Aggressive bone tumors usually present with pain, whereas active lesions present with pain or pathologic fracture. Only aggressive benign bone tumors are associated with a soft-tissue mass, and they are far less common than indolent bone tumors, especially in children. Aboulafia AJ, Kennon RE, Jelinek JS: Benign bone tumors of childhood. J Am Acad Orthop Surg 1999;7:377-388.

The brachialis muscle typically receives dual innervation. The major portion is innervated by the musculocutaneous nerve. Its inferolateral portion is innervated by the radial nerve. The others listed have single innervation. The anterior approach to the humerus, which requires splitting of the brachialis, capitalizes on this dual innervation.

The child has Kohler's disease. This is a self-limiting osteochondritis of the navicular. It is treated symptomatically with initial cast immobilization for 6 to 12 weeks, followed possibly by orthotic management. Findings shown in the radiograph usually will normalize within 1 year, and there are no long-term sequelae. Borges JL, Guille JT, Bowen JR: Kohler's bone disease of the tarsal navicular. J Pediatr Orthop 1995;15:596-598.

The relationship between the distal articular surface of the first metatarsal head and the long axis of the first metatarsal is called the distal metatarsal articular angle. This angle has been validated by Richardson and associates to measure and determine the congruence of the first metatarsophalangeal joint. This angle is critical in determining the appropriate surgical procedure to perform on a patient with a bunion deformity because a congruent joint requires a procedure to maintain congruence of the articular surfaces following osteotomy. Therefore, a chevron becomes a biplanar chevron, and a Lapidus procedure adds a second osteotomy of the distal metatarsal to tilt the metatarsal head into a congruent location. Coughlin MJ: Juvenile hallux valgus: Etiology and treatment. Foot Ankle Int 1995;16:682-697. Steel MW III, Johnson KA, DeWitz MA, et al: Radiographic measurements of the normal foot. Foot Ankle 1980;1:151-158.

The radiographs show a patellar tendon rupture following a total knee replacement. This infrequent, but serious, complication is reported to occur in 0.17% to 1.4% of patients after total knee arthroplasty. Although the radiographs show concerning features such as incomplete tibial and femoral periprosthetic lucencies, it is most important for the surgeon to recognize extensor mechanism disruption. Insall J, Salvati E: Patella position in the normal knee joint. Radiology 1971;101:101-104. Lynch AF, Rorabeck CH, Bourne RB: Extensor mechanism complications following total knee arthroplasty. J Arthroplasty 1987;2:135-140.

In a type III supracondylar distal humerus fracture of the elbow, the brachial artery can become incarcerated, yielding a pulseless extremity. In this situation, closed reduction may not be effective; therefore, open management is often necessary. The preferred surgical approach to the brachial artery and to this fracture is the anterior approach to the cubital fossa. The lacertus fibrosis is incised, and the dissection is carried out between the brachialis (musculocutaneous nerve) and the pronator teres (median nerve), mobilizing the brachial artery. Once the brachial artery is mobilized, the anterior elbow joint capsule may be exposed. The interval between the brachialis and the biceps describes the anterolateral approach to the elbow more commonly used for exposure of the proximal aspect of the posterior interosseous nerve. The dissection interval between the brachioradialis and the pronator teres describes the proximal extent of the anterior approach to the radius. Tubiana R, McCullough CJ, Masquelet AC: An Atlas of Surgical Exposures of the Upper Extremity. Philadelphia, PA, JB Lippincott, 1990, p 115.

A complete tear of the distal biceps brachii most often occurs from a large, rapid eccentric elbow extension load. A pop or tearing sensation usually occurs, and a palpable defect in the antecubital fossa is often present on examination. The treatment of choice is a direct primary repair by a two-incision technique. If left unrepaired, the most disabling consequence is the loss of forearm supination strength. It is unlikely that significant elbow or forearm motion will be lost if the rupture is left unrepaired and early motion exercises are initiated. Elbow flexion strength tends to return with time, but the loss of forearm supination strength remains problematic. D'Alessandro DF, Shields CL Jr, Tibone JE, Chandler RW: Repair of distal biceps tendon ruptures in athletes. Am J Sports Med 1993;21:114-119.

The hypoglossal nerve exits from the ansa cervicalis at approximately the C2-3 level and can be injured during retraction up to the C2 level. The superior laryngeal nerve lies at about C4-5. The facial nerve is much higher. The vagus nerve runs with the internal jugular and carotid much more laterally. The phrenic nerve exits posteriorly. Chang U, Lee MC, Kim DH: Anterior approach to the midcervical spine, in Kim DH, Henn JS, Vaccaro AR, et al (eds): Surgical Anatomy and Techniques to the Spine. Philadelphia, PA, Saunders Elsevier, 2006, pp 45-54.