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

Morphologic and anatomic studies confirm the pedicle is smaller on the concave side of thoracic curves. The dura is also closer to the pedicle on the concave side of the curves. Liljenqvist U, Allkemper T, Hackenberg L, et al: Analysis of vertebral morphology in idiopathic scoliosis with use of magnetic resonance imaging and multiplanar reconstruction. J Bone Joint Surg Am 2002;84:359-368.

The patient has the classic signs of Little Leaguer's shoulder, with findings that include pain localized to the proximal humerus during the act of throwing and radiographic evidence of widening of the proximal humeral physis. Examination usually reveals tenderness to palpation over the proximal humerus, but the presence of any swelling, weakness, atrophy, or loss of motion is unlikely. The treatment of choice is rest from throwing for at least 3 months, followed by a gradual return to pitching once the shoulder is asymptomatic. Carson WG Jr, Gasser SI: Little Leaguer's shoulder: A report of 23 cases. Am J Sports Med 1998;26:575-580.

Exposure of polyethylene to radiation and then heating it to quench the free radicals leads to a cross-linked material. It converts a high molecular weight polyethylene macromolecule to an interpenetrating network structure of polymer chains. The ductility of the material is decreased, hence the greater risk of fracture. While the wear rate (measured as fewer and smaller particles) against a smooth counterface is markedly reduced, cross-linked polyethylene has shown a larger increase in wear rate when a rougher counterface is used compared to noncross-linked material. Due to reduced mechanical strength, highly cross-linked polyethylene is less resistant to abrasive wear.

Popliteal snapping syndrome represents the most likely diagnosis. Barnes and Scott noted that the popliteus tendon can be a potential source of internal derangement after total knee arthroplasty. They noted that it can be subluxated anteriorly and posteriorly over a retained lateral femoral condyle osteophyte. Allardyce and associates described the condition as a popliteus condition, snapping as it rolls over a retained lateral femoral condylar osteophyte. Patellar clunk syndrome is a distinct syndrome associated with the patella and has been reported in posterior stabilized knees. In addition to crepitation with range of motion, the patella literally snaps or jumps as the knee is taken from flexion to extension. Beight JL, Yao B, Hozack WJ, et al: The patellar "clunk" syndrome after posterior stabilized total knee arthroplasty. Clin Orthop 1994;299:139-142. Barnes CL, Scott RD: Popliteus tendon dysfunction following total knee arthroplasty. J Arthroplasty 1995;10:543-545.

Bisphosphonates are stable analogues of pyrophosphate that have a strong affinity for bone hydroxyapatite; these agents inhibit bone resorption by reducing the recruitment and activity of osteoclasts and increasing apoptosis. Bone formed while patients are receiving bisphosphonate treatment is histologically normal. Bisphosphonates have been shown to be effective in decreasing pathologic fractures, bone pain, and the need for radiation therapy in patients with multiple myeloma and metastatic carcinoma to bone. The most effective method of administration is via monthly intravenous infusion. Osteonecrosis of the mandible is sometimes a complication of this treatment. Gass M, Dawson-Hughes B: Preventing osteoporosis-related fractures: An overview. Am J Med 2006;119:S3-S11.

Dislocation following total hip arthroplasty is twice as common in women than in men. It is more likely to occur in older patients. There is no clear association between dislocation and the method of fixation or the type of bearing, so long as the bearing diameter is the same.

Motion segments that demonstrate more than 4 mm of translation or 10 degrees of angulation compared with adjacent motion segments on flexion-extension radiographs have excessive motion and instability. Anterior marginal osteophytes form at the insertion of the annulus from increased forces but do not indicate increased motion. A spondylolisthesis or lateral listhesis is often static without increased motion. More than 3.5 mm of translation or 11 degrees of angulation is considered instability criteria for the cervical spine. Internal disk disruption does not denote instability. Boden SD, Wiesel SW: Lumbosacral segmental motion in normal individuals. Have we been measuring instability properly? Spine 1990;15:571-576.

The patient has an acute grade III posterior cruciate ligament injury. The majority of grade I and II injuries can be treated with protected weight bearing and quadriceps rehabilitation, and most patients can return to sports within 2 to 4 weeks. In contrast, grade III injuries require immobilization in full extension for 2 to 4 weeks to protect the posterior cruciate ligament and the other posterolateral structures presumed to be damaged. The mainstay of postinjury rehabilitation for all posterior cruciate ligament injuries is quadriceps strengthening exercises, which have been shown to counteract posterior tibial subluxation. Miller MD, Bergfeld JA, Fowler PJ, Harner CD, Noyes FR: The posterior cruciate ligament injured knee: Principles of evaluation and treatment. Instr Course Lect 1999;48:199-207.

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.

The rate of symptomatic degeneration at an adjacent segment warranting either decompression or arthrodesis was predicted to be 16.5% at 5 years and 36.1% at 10 years based on a Kaplan-Meier analysis.

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.

When you are employed as a team physician, you are obligated to inform the players and the team organization of all athletically relevant medical issues. This differs significantly from the normal rule of patient confidentiality. If the player came to see you and you were not the team physician, you may not inform the team unless the player so desires. As the team physician, you are not obligated to inform the media. Tucker AM: Ethics and the professional team physician. Clin Sports Med 2004;23:227-241.

The images show a complex, lobular lesion of the thigh that has signal characteristics that follow fat. The size of the lesion, the areas of stranding within the mass, along with mild uptake on the gadolinium sequences and the mild edema within the lesion on the T2-weighted image make liposarcoma the most likely diagnosis and simple intramuscular lipoma far less likely. All other diagnoses listed would not follow fat characteristics shown on the MRI sequences.

Crossover second toes are attributed to attenuation or rupture of the plantar plate and lateral collateral ligament and are associated with varying degrees of instability. Flexor-to-extensor transfer (Girdlestone/Taylor procedure) can provide intrinsic stability to the toe. Although plantar metatarsal head condylectomy can increase stability by resulting in scarring of the plantar plate, excision of the entire second metatarsal head carries a high risk of transfer metatarsalgia. Removal of the base of the proximal phalanx destabilizes the toe and should be reserved as a salvage procedure. Simple flexor tenotomy alone will not improve stability, and arthrodesis of the second metatarsophalangeal joint will limit motion and impair function. Coughlin MJ: Crossover second toe deformity. Foot Ankle 1987;8:29-39.

A player who has an acute cervical disk herniation should not be allowed to return to play until the acute phase is over. Certain players with large herniations may require surgery before returning to play to eliminate the risk of disk-related stenosis and cord compression. Morganti C, Sweeney CA, Albanese SA, Burak C, Hosea T, Connolly PJ: Return to play after cervical spine injury. Spine 2001;26:1131-1136.

The findings are consistent with a neurapraxia of the anterior interosseous branch of the median nerve. This is the most common nerve palsy seen with supracondylar humerus fractures, followed closely by radial nerve palsy. Nearly all cases of neurapraxia following supracondylar humerus fractures resolve spontaneously, and therefore, further diagnostic studies and surgery are not indicated. Cramer KE, Green NE, Devito DP: Incidence of anterior interosseous nerve palsy in supracondylar humerus fractures in children. J Pediatr Orthop 1993;13:502-505.

The patient has a complete tear of the ulnar collateral ligament as defined by MCP joint laxity of greater than 30 degrees (or 15 degrees greater laxity compared with the opposite side). Primary repair is the treatment of choice because displacement of the ligament superficial to the adductor aponeurosis (Stener lesion) must be corrected. Any volar plate injury can be addressed during repair of the ulnar collateral ligament.

Cadaveric studies have shown that external rotation of the tibia is most pronounced following transection of the posterior cruciate and lateral collateral ligaments with the knee at 90 degrees of flexion. Isolated release of the lateral collateral ligament results in increased external tibial rotation at 30 degrees. Gollehon DL, Torzilli PA, Warren RF: The role of the posterolateral and cruciate ligaments in the stability of the human knee: A biomechanical study. J Bone Joint Surg Am 1987;69:233-242. Cooper DE: Tests for posterolateral instability of the knee in normal subjects: Results of examination under anesthesia. J Bone Joint Surg Am 1991;73:30-36.

Split posterior tibial tendon transfers are best performed in patients with spastic cerebral palsy who are between the ages of 4 and 7 years and have flexible equinovarus deformities. Rigid deformities typically require bony reconstruction procedures. Tendon transfers in patients with athetosis are unpredictable. Green NE, Griffin PP, Shiavi R: Split posterior tibial-tendon transfer in spastic cerebral palsy. J Bone Joint Surg Am 1983;65:748-754.

If the neck is immobilized in excessive extension, it can be difficult for the patient to swallow. If the patient had injured the recurrent or superior laryngeal nerve at the time of the accident, it is likely to have manifested itself earlier on. Esophageal trauma or retropharyngeal edema or hematoma from the fracture also should have manifested itself earlier. Because the fracture was completely reduced, it is unlikely that moving the small fragment posteriorly would have injured the esophagus. Garfin SR, Botte MJ, Waters RL, Nickel VL: Complications in the use of halo fixation device. J Bone Joint Surg Am 1986;68:320-325.

Normal articular cartilage is composed of three zones that are based on the shape of the chondrocytes and the distribution of the type II collagen. The tangential zone has flattened chondrocytes, condensed collagen fibers, and sparse proteoglycan. The intermediate zone is the thickest layer with round chondrocytes oriented in perpendicular or vertical columns paralleling the collagen fibers. The basal layer is deepest with round chondrocytes. The tidemark is deep to the basal layer and separates the true articular cartilage from the deeper cartilage that is a remnant of the cartilage anlage, which participated in endochondral ossification during longitudinal growth in childhood. The tidemark divides the superficial uncalcified cartilage from the deeper calcified cartilage and also is the division between nutritional sources for the chondrocytes. The tidemark is the zone in which chondrocyte renewal took place in childhood. The tidemark is found only in joints and not in the cap of an enchondroma. It is seen most prominently in the adult, nongrowing joint.

Due to the relatively high incidence of delayed union and nonunion associated with this mildly displaced Jones-type fracture, and the temporal proximity to his playing season, intramedullary screw fixation is the treatment of choice in this collegiate athlete to best ensure healing and expedite his return to football. If nonsurgical management were elected, application of a non-weight-bearing short leg cast would be appropriate since a higher likelihood of healing is expected with it versus a short leg walking cast. The risk of recurrent fracture of fractures that heal with nonsurgical management has reportedly been high (approximately 30%). Quill GE: Fractures of the proximal fifth metatarsal. Orthop Clin North Am 1995;26:353-361. Torg JS, Balduini FC, Zelko RR, et al: Fractures of the base of the fifth metatarsal distal to the tuberosity: Classification and guidelines for nonsurgical and surgical management. J Bone Joint Surg Am 1984;66:209-214.

Precoating of the femoral stem with PMMA results in increased bonding of the stem to the cement mantle. However, this has not been shown to result in superior survivorship compared with nonprecoated stems of similar design. In one series, the rate of revision of precoated stems was greater than that of nonprecoated cohorts. The wear and infection rates have not been shown to differ between precoated and nonprecoated stems. Sporer SM, Callaghan JJ, Olejniczak JP, Goetz DD, Johnston RC: The effects of surface roughness and polymethylmethacrylate precoating on the radiographic and clinical results of the Iowa hip prosthesis: A study of patients less than fifty years old. J Bone Joint Surg Am 1999;81:481-492.

This approach is criticized for the episodic limp associated with the muscle detachment and reattachment. Classically, two thirds of the gluteus medius is detached as a sleeve with the vastus lateralis. This exposes the gluteus minimus and the ligament of Bigelow. These must also be detached to allow dislocation of the hip and osteotomy of the femoral neck. The rectus femoris lies medially and anteriorly and does not need to be addressed. The piriformis and obturator internus are exposed during the posterior approach. Neither the gluteus maximus nor tensor fascia lata attach to the anterior femur. The sartorius and iliopsoas are not exposed during this dissection. Hoppenfeld S, deBoer P (eds): Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, pp 333-335.

The radiographs show localized diffuse cortical thickening that is characteristic of melorheostosis. The condition may be monostotic or it may involve many bones in one extremity (monomelic) in the distribution of a sclerotome. Bone scans will show increased uptake at the site or sites of skeletal involvement. Long tubular bones are most commonly involved. Melorheostosis is usually asymptomatic and requires no treatment. On rare occasions, there may be associated soft-tissue contractures. Dorfman H, Czerniak B: Bone Tumors. St Louis, MO, Mosby Inc, 1998, pp 1105-1107. Campbell CJ, Papademetriou T, Bonfiglio M: Melorheostosis: A report of the clinical, roentgenographic, and pathological findings in fourteen cases. J Bone Joint Surg Am 1968;50:1281-1304.

The patient has a severe high-energy injury from axial loading to the left ankle and distal tibia. This is a closed injury, but the soft tissues are injured and severely swollen. Initial treatment should focus on skeletal stabilization, and incisions directly over the fracture area should be avoided until soft-tissue stabilization has occurred. Immediate spanning external fixation with plans for a delayed reconstruction as needed for the joint surface is the treatment of choice. Closed reduction and application of a constrictive long leg cast may lead to increased risk of tissue necrosis. Immediate open procedures to internally fix the fracture add the risks of soft-tissue necrosis and are to be avoided. Percutaneous plating may be one of the delayed fixation options but should not be used immediately. Primary ankle arthrodesis is not indicated. Thordarson DB: Complications after treatment of tibial pilon fractures: Prevention and management strategies. J Am Acad Orthop Surg 2000;8:253-265. Marsh JL, Bonar S, Nepola JV, DeCoster TA, Hurwitz SR: Use of an articulated external fixator for fractures of the tibial plafond. J Bone Joint Surg Am 1995;77:1498-1509.

Patients with Duchenne's muscular dystrophy show progressive muscular weakness because of the absence of dystrophin and have the clinical picture of progressive muscle weakness. The condition is an X-linked genetic disease. Fitzgerald RH, Kaufer H, Malkani AL: Orthopaedics. St Louis, MO, Mosby Year Book, 2002, pp 1573-1583.

The radioscaphocapitate ligament is the most radial of the extrinsic volar ligaments of the wrist. It has a mean attachment to the radius 4 mm from the tip of the radial styloid. Nakamura T, Cooney WP III, Lui WH, et al: Radial styloidectomy: A biomechanical study on the stability of the wrist joint. J Hand Surg Am 2001;26:85-93.

The scans show a lipohemarthrosis. There is the characteristic layering of a superior zone containing fat (high signal intensity), a central zone containing serum (low signal intensity), and an inferior zone that contains red blood cells (low signal intensity). The most common cause of a lipohemarthrosis is an intra-articular fracture with leakage of marrow fat into the joint. 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.

In a review of 13,000 spinal procedures, nine patients were treated with heparin following development of pulmonary emboli. Of these patients, six had serious complications ranging from wound drainage to paralysis. Heparin therapy instituted within 10 days of the surgical procedure resulted in a 100% complication rate. Vena cava filter placement has a complication rate of 0.12% to 10.1%. Removable filters are currently in clinical trials. Cain JE Jr, Major MR, Lauerman WC, et al: The morbidity of heparin therapy after development of pulmonary embolus in patients undergoing thoracolumbar or lumbar spinal fusion. Spine 1995;20:1600-1603. Roberts AC: Venous imaging and inferior vena cava filters. Curr Opin Radiol 1992;4:88-96.

Tensile testing of the inferior glenohumeral ligament at near physiologic strain rates has shown that the anterior band of the IGHL has the greatest stiffness of the three ligament regions and the glenoid insertion site shows greater strain than the ligament midsubstance. Bigliani LU, Pollock RG, Soslowsky LJ, Flatow EL, Pawluk RJ, Mow VC: Tensile properties of the inferior glenohumeral ligament. J Orthop Res 1992;10:187-197.

The patient has a significant hallux valgus and instability of the first ray, causing transfer metatarsalgia to the second metatarsal head. Therefore, the best procedure is fusion of the metatarsal cuneiform joint with soft-tissue realignment of the first metatarsophalangeal joint. This procedure provides the best chance of relieving symptoms under the second metatarsal head, as well as correcting the hallux valgus.

Curettage and bone grafting typically is the preferred method of treatment for chondroblastoma, with local recurrence rates of approximately 10%. Some clinicians advocate the addition of adjuvants such as phenol. Left alone, these lesions can destroy bone and invade the joint. Large intra-articular lesions may require major joint reconstruction. Wide local excision rarely is required to eradicate the tumor. Radiation therapy rarely is indicated and only for unresectable or multiply recurrent lesions. Springfield DS, Capanna R, Gherlinzoni F, Picci P, Campanacci M: Chondroblastoma: A review of seventy cases. J Bone Joint Surg Am 1985;67:748-755.

The overriding factor determining treatment in this case is the appearance of the surgical wound. Based on MacPhearson's work, this "C" wound is best managed with two-stage exchange. The functional outcome is markedly diminished following a knee arthrodesis compared to revision knee arthroplasty. Harwin SF: The diagnosis and management of infected total knee replacement. Seminars Arthroplasty 2002;13:9-22. Goldmann RT, Scuderi GR, Insall JN: 2-stage reimplantation for infected total knee replacement. Clin Orthop 1996;331:118-124.

The radiograph is consistent with a unicameral (simple) bone cyst. The MRI scan reveals that the cyst is juxtaposed to the physis and therefore can be classified as active (latent cysts are more than 1 cm away from the physis). Active cysts are treated with aspiration and steroid injection, although repeated injections may be necessary. Curettage and bone grafting results in more reliable healing but may lead to growth arrest in active cysts. Iannotti JP, Williams GR: Disorders of the Shoulder: Diagnosis and Management, ed 1. Philadelphia, PA, Lippincott Williams & Wilkins, 1999, pp 945-946.

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 patient has a tension pneumothorax. This is a life-threatening emergency where air is trapped between the pleura and the lung, which prevents expansion of the lung. This causes hypoxia and cardiopulmonary compromise. The first line of treatment is to place a needle into the second intercostal space in the midclavicular line. The athlete should then be transported to the emergency department for chest tube placement. The athlete cannot return to play, and resuscitation is not necessary because he has not gone into cardiopulmonary arrest. Amaral JF: Thoracoabdominal injuries in the athlete. Clin Sports Med 1997;16:739-753.

Ewing's sarcoma is the second most common primary tumor of bone in children. Depending on the site and extent of disease, chemotherapy, radiation therapy, and surgery are all treatment options. In this patient with extensive pelvic and metastatic disease, chemotherapy and radiation therapy offer the best oncologic control while preserving functional outcome. Gibbs CP Jr, Weber K, Scarborough MT: Malignant bone tumors. Instr Course Lect 2002;51:413-428. Thacker MM, Temple HT, Scully SP: Current treatment for Ewing's sarcoma. Expert Rev Anticancer Ther 2005;5:319-331.

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.

The patient has infantile fibrosarcoma. For unresectable lesions, the treatment of choice is chemotherapy with vincristine, actinomycin-D, and cyclophosphamide, followed by excision if there is an adequate decrease in the size of the lesion.

Convex hemiarthrodesis and hemiepiphysiodesis are procedures designed to gradually reduce curve magnitude in congenital scoliosis because of hemivertebrae. They are used to surgically create an anterior and posterior bar to arrest growth on the convexity of the existing deformity. Success of the technique is predicated on continued growth on the concave side of the deformity. Prerequisites for this procedure include curves of limited length (less than or equal to five vertebrae), curves of reasonable magnitude (less than 70 degrees), absence of kyphosis, concave growth potential, and appropriate age (younger than age 5 years).

Osteoid osteomas are painful bone lesions, with radiographs revealing a dense sclerotic cortex surrounding a small radiolucency or nidus. Symptoms often are worse at night but usually are not activity related. While treatment in the past has consisted of open en bloc excision, current means of removal include percutaneous drilling under CT guidance and percutaneous radiofrequency coagulation. Success rates of percutaneous treatment are comparable to those seen following open procedures. The characteristic radiographic appearance of this lesion usually obviates the need for biopsy. Because the lesion is not caused by pyogenic organisms, antibiotics are not indicated. Donahue F, Ahmad A, Mnaymneh W, Pevsner NH: Osteoid osteoma: Computed tomography guided percutaneous excision. Clin Orthop 1999;366:191-196.

The extensor carpi radialis brevis, supinator muscle, arcade of Frohse, and leash of Henry are potential sites of compression for the posterior interosseous nerve. The most common location of spontaneous entrapment is the arcade of Frohse. The lateral intermuscular septum is a site of compression for the radial nerve.

Postoperative subscapularis detachment can be identified with a positive lift-off test that reveals weakness in internal rotation. This complication does not necessarily compromise the anterior capsule repair. The load-and-sift maneuver and articular contrast studies may be normal. Supraspinatus tests for impingement and weakness should be negative. Gerber C, Krushell RJ: Isolated ruptures of the tendon of the subscapularis muscle: Clinical fractures in 16 cases. J Bone Joint Surg Br 1991;73:389-394.

Meniscal tears have many configurations and locations. The normal medial meniscus has a bow-tie configuration on the two most medial consecutive sagittal views. Toward the center of the joint the anterior and posterior horns have a triangular shape. These images show an abnormal intra-articular low-signal structure located anterior to the intact posterior cruciate ligament. This most likely represents a torn and displaced posterior horn of the medial meniscus, sometimes called "double PCL sign". A popliteal cyst and ligaments of Wrisberg and Humphry are not visible on these figures. Helms CA: MR image of the knee, in Fundamentals of Skeletal Radiology, ed 2. Philadelphia, PA, WB Saunders, 1995, pp 172-191.

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.

Sodium deficiency is the cause of heat cramps. It is the principle electrolyte of sweat and is readily lost during training, especially in warmer temperatures. The condition can be avoided by adding extra table salt to food and maintaining good hydration before and after sports activities. Salt tablets are to be avoided when a patient has heat cramps because the high soluble load will cause gastric irritation. Bergeron MF, Armstrong LE, Maresh CM: Fluid and electrolyte losses during tennis in the heat. Clin Sports Med 1995;14:23-32.

Freiberg's infraction is believed to be an osteochondrosis of the second metatarsal head. It is the only osteochondrosis that has a predilection for females. The typical patient is an athletically active adolescent female. The radiograph shows stage II disease wherein reossification is occurring; it is at this time that the second metatarsal head is most susceptible to deformation. Therefore, initial management should consist of a short leg walking cast.

When markedly diminished space available for the cord (demonstrated by a posterior atlantoaxial interval of less than 10 mm) is seen, there is a poor prognosis for recovery (25% of Ranawat class IIIb patients) following surgery. A posterior atlantoaxial interval of 14 mm or less is a predictor of increased risk of paralysis, but patients with an interval between 10 mm and 14 mm have a greater chance of recovery. Space available for the cord that is at least 14 mm is not associated with an increased risk of neurologic deficit. Boden SD, Dodge LD, Bohlman HH, et al: Rheumatoid arthritis of the cervical spine: A long-term analysis with predictors of paralysis and recovery. J Bone Joint Surg Am 1993;75:1282-1297.

The indications of bisphosphonate therapy in breast cancer patients range from the correction of hypercalcemia to the prevention of cancer treatment-induced bone loss. Bisphosphonates reduce metastatic bone pain in at least 50% of patients and can reduce the frequency of skeletal-related events by 30% to 40%. Osteonecrosis of the jaw could occur in up to 2.5% of breast cancer patients during long-term bisphosphonate therapy.

The radiographs show the characteristic features of osteopetrosis. The condition results from defective resorption of immature bone by osteoclasts. There are three distinct clinical forms: (1) infantile-malignant, which is autosomal recessive and fatal in the first few years of life if untreated; (2) intermediate autosomal recessive; and (3) autosomal dominant. These conditions do not follow a malignant course, and patients have normal life expectancy with orthopaedic problems and anemia. In the malignant form, the clinical features include frequent fractures, macrocephaly, progressive deafness and blindness, hepatosplenomegaly, and severe anemia beginning in early infancy or in utero. Deafness and blindness are generally thought to represent effects of pressure on nerves and usually occur later in life. The anemia is caused by encroachment of bone on marrow, resulting in obliteration, and the hepatosplenomegaly is caused by compensatory extramedullary hematopoiesis. Dental caries and abscesses, as well as osteomyelitis of the mandible, are also seen. Most patients have normal intelligence. Treatment of the malignant form includes high dose 1,25 dihydroxy vitamin D with a low-calcium diet to stimulate bone resorption, not because there are vitamin deficiencies. Bone marrow transplant has also been successful. Herring JA: Tachdjian's Pediatric Orthopedics, ed 4. Philadelphia, PA, WB Saunders, 2002, p 1550. Zaleske DJ: Metabolic and endocrine abnormalities, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, pp 212-214.

Distant bone metastasis is associated with an extremely poor prognosis for patients with osteosarcoma (5-year survival rate of less than 10%). Most osteosarcomas are high grade and extracompartmental, and approximately half are greater than 8 cm at presentation. The 5-year survival rate for these patients is approximately 70%. Patients with a solitary pulmonary metastasis have a prognosis worse than patients without detectable metastases but not as bad as those with bone metastases. Bielack SS, Kempf-Bielack B, Delling G, et al: Prognostic factors in high-grade osteosarcoma of the extremities or trunk: An analysis of 1,702 patients treated on neoadjuvant cooperative osteosarcoma study group protocols. J Clin Oncol 2002;20:776-790. Heck RK, Stacy GS, Flaherty MJ, et al: A comparison study of staging systems for bone sarcomas. Clin Orthop Relat Res 2003;415:64-71.

The patient has an atypical adult flatfoot deformity. The radiographs reveal forefoot abduction, mild loss of calcaneal pitch, and marked plantar flexion sag through the naviculocuneiform joint. The inability to perform a single limb heel rise indicates that the posterior tibial tendon is nonfunctional; however, the deformity remains flexible. In this patient, surgical treatment should include a tendon transfer, lateral column lengthening, medial column arthrodesis, and heel cord lengthening. Because a substantial portion of the deformity stems from the naviculocuneiform joint in this instance, tendon transfer and lateral column lengthening alone provide insufficient deformity correction. Triple arthrodesis and heel cord lengthening is best reserved for fixed flatfoot deformities. Soft-tissue procedures alone are associated with a high failure rate, as are attempted tendon repairs. Greisberg J, Assal M, Hansen ST Jr, et al: Isolated medial column stabilization improves alignment in adult-acquired flatfoot. Clin Orthop Relat Res 2005;435:197-202.

The patient has an isthmic spondylolysis. The plain radiographs are normal, but the MRI scans show increased marrow edema and signal at the L5 pars interarticularis. Findings of bilateral hamstring tightness and increased pain with extension over flexion suggests spondylolysis. The MRI scans do not show any signs of the other conditions. Wiltse LL, Rothman SL: Spondylolisthesis: Classification, diagnosis and natural history. Sem Spine Surg 1993;5:264-280.

An extended trochanteric osteotomy has been shown to be very efficient in removing a well-fixed distal implant and cement with minimal complications. Direct lateral, posterior, and transtrochanteric osteotomy exposures do not provide exposure of the midfemur.

The severe depression of the proximal medial tibial epiphysis is most consistent with the diagnosis of neglected infantile Blount's disease. Blount's disease in adolescents produces a deformity in the metaphyseal region. Septic arthritis and JRA affect both sides of the joint. Hemophilia produces a characteristic widening of the intercondylar notch. Thompson GH, Carter JR: Late-onset tibia vara (Blount's Disease). Clin Orthop 1990;255:24-35.

Etanercept is a molecule consisting of the Fc portion of IgG fused to the extracellular domain of the p76 human THF-a receptor. It is soluble and binds TNF-a. Infliximab is the monoclonal antibody that binds TNF-a. IL-1 receptor antagonists are still in development. Leflunomide is a drug that inhibits pyrimidine synthesis and is similar to methotrexate as an antimetabolite.

The hallmark for RSD or SMP is the presence of pain that is out of proportion to that expected for the degree of the injury. SMP often extends well beyond the involved area and is present in a nonanatomic distribution. The pain is frequently described as a burning sensation, with extreme sensitivity to light touch. Joint stiffness can be present but is a nonspecific finding. There may be cold intolerance, but this is not a cardinal symptom. Sweating actually may be increased. Osteopenia, if present, is a late finding. Lindenfeld TN, Bach BR Jr, Wojtys EM: Reflex sympathetic dystrophy and pain dysfunction in the lower extremity. Instr Course Lect 1997;46:261-268.

Mineralization occurs at the site of hole zones between the collagen fibrils. Crystals begin from the necessary ions of the lattice that come together with the correct orientation to form the first stable crystal. Formation of this critical nucleus is the most energy-demanding step of crystallization. Enzymes within the extracellular matrix vesicles degrade inhibitors such as adenosine triphosphate, pyrophosphate, and proteoglycans found in the surrounding extracellular matrix. Bone mineral consists of numerous impurities (carbonate, magnesium) that are more soluble, allowing the bone to act as a reservoir for calcium, phosphate, and magnesium ions. Crystals may form by addition of ions or ion clusters to the critical nucleus in many directions, with 'kink' sites forming to branch and exponentially proliferate the crystals. Macromolecules facilitate formation of the critical nucleus and increasing local concentrations of necessary ions. Once the crystals are formed and proliferating, macromolecules bind to the surface and block the growth of the crystal, regulating size, shape, and number of crystals. Lian JB, Stein GS, Canalis E, et al: Bone formation: Osteoblast lineage cells, growth factors, matrix proteins, and the mineralization process, in Favus MJ (ed): Primer on Metabolic Bone Diseases and Disorders of Mineral Metabolism, ed 4. Philadelphia, PA, Lippincott Williams & Wilkins, 1999, pp 14-29.

Ewing's sarcoma typically can occur in the diaphysis of the long bones (50% to 55%). It is often accompanied by a large soft-tissue mass. Abnormal findings are common, including a low-grade fever, an elevated ESR, and leukocytosis. The histology is consistent with a small round blue cell tumor. The unique pathology and other findings exclude osteosarcoma. Giant cell tumor and chondrosarcoma have a different histologic appearance and typically are more metaphyseal in location. Chondrosarcoma typically is found in older age groups, has a different histologic pattern, and rarely occurs in the midshaft of the femur.

The blood supply to the adult capitellum and lateral trochlea comes from posterior vessels arising from the radial recurrent, radial collateral, and interosseous recurrent arteries. These arteries penetrate the distal humerus posterior and superior to the capitellum.

The patient has a grade 4 spondylolisthesis. Optimal surgical management is posterior spinal fusion from L4 to the sacrum. The use of instrumentation is controversial. Vertebrectomy is typically reserved for spondylo-optosis (grade 5) cases. Spinal fusion from L5 to S1 usually is not successful for a slip that is greater than 50%. Isolated anterior spinal fusion has not been successful, and direct repair of the pars defect is only useful for spondylolysis without spondylolisthesis. Lenke LG, Bridwell KH: Evaluation and surgical treatment of high-grade isthmic dysplastic spondylolisthesis. Instr Course Lect 2003;52:525-532.

The lateral cord divides into the musculocutaneous and median nerves. The posterior cord terminates into the axillary and radial nerves. The medial cord divides into the ulnar and median nerves. Hollinshead WH: Anatomy for Surgeons, ed 3. Philadelphia, PA, Harper and Row, 1982, pp 228-236.

This cuboid compression fracture ("nutcracker" injury) is associated with subtle injury to the Lisfranc complex. This diagnosis must be made to ensure proper treatment.

Using the traditional concussion grading scale, the patient sustained a grade I concussion because he did not lose consciousness and his abnormal cognitive level lasted less than 1 hour. If this was the player's first concussion, theoretically he could return to play later in the game provided that he had no confusion, headache, or associated symptoms. However, because it was the third concussion for the year, participation in contact sports should be terminated for the season. Guskiewwicz KM, Barth JT: Head injuries, in Schenk RC Jr (ed): Athletic Training and Sports Medicine. Rosemont, IL, American Academy of Orthopedic Surgeons, 1999, pp 143-167.

Children with spastic diplegic cerebral palsy often have contractures of multiple joints. Because the gait abnormalities can be complex, isolated surgery is rarely indicated. To avoid compensatory deformities at other joints, it is preferable to correct all deformities in a single operation. Isolated heel cord lengthening in the presence of tight hamstrings and hip flexors will lead to progressive flexion at the hips and knees, thus worsening a crouched gait. Split posterior tibial tendon transfer is used for patients with hindfoot varus, which is not present in this patient. Gage JR: Distal hamstring lengthening/release and rectus femoris transfer, in Sussman MD (ed): The Diplegic Child. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1992, pp 324-326.

Because the radiographs demonstrate severe arthritis, hallux metatarsophalangeal arthrodesis is the treatment of choice. Cheilectomy alone will not relieve pain because the entire joint is degenerative. Joint replacement has not been shown to be a long-term solution. Keller resection arthroplasty is not indicated in younger active patients. Hallux valgus correction will not address arthritis of the joint and could stiffen the joint further. Smith RW, Joanis TL, Maxwell PD: Great toe metatarsophalangeal joint arthrodesis: A user-friendly technique. Foot Ankle 1992;13:367-377.

Osteosarcoma is the most common primary malignant bone tumor (5.6 per 1 million children younger than age 15 years), and Ewing's sarcoma is second (2.1 per 1 million children). Giant cell tumor and chondrosarcoma are rare in children. Osteochondroma is more common than any of the above tumors in children, but it is not malignant. Himelstein BP, Dormans JP: Malignant bone tumors of childhood. Pediatr Clin North Am 1996;43:967-984. Pierz KA, Womer RB, Dormans JP: Pediatric bone tumors: Osteosarcoma, Ewing's sarcoma, and chondrosarcoma associated with multiple hereditary osteochondromatosis. J Pediatr Orthop 2001;21:412-418.

The radiograph reveals a four-part fracture-dislocation of the proximal humerus. Humeral hemiarthroplasty and tuberosity repair is the treatment of choice because the risk of osteonecrosis is high after attempted repair of this injury. Glenoid resurfacing is reserved for acute fractures in which there is significant preexisting glenoid arthrosis, such as in patients with rheumatoid arthritis. Neer CS II: Displaced proximal humeral fractures: II. Treatment of three- and four-part displacement. J Bone Joint Surg Am 1970;52:1090-1103.

The radiographs show a fracture of the distal radius and ulna physis. The most likely complication is growth arrest of the distal ulna. In contradistinction to physis fractures of the radius (growth arrest incidence of less than 5%), the incidence of growth arrest in the ulna is between 30% and 40%. Entrapment of the EPL tendon and cross union between the two bones is extremely rare. Vanheest A: Wrist deformities after fracture. Hand Clin 2006;22:113-120. Cannata G, De Maio F, Mancini F, et al: Physeal fractures of the distal radius and ulna: Long-term prognosis. J Orthop Trauma 2003;17:172-179. Ray TD, Tessler RH, Dell PC: Traumatic ulnar physeal arrest after distal forearm fractures in children. J Pediatr Orthop 1996;16:195-200.

In the early 1990s, a transition was made from a two-incision ACL reconstruction to a single-incision ACL reconstruction, and there was concern over divergence of the femoral screws. It was shown radiographically that approximately 5% of the time, divergence of the screw was greater than 15 degrees from the bone plug. In a bovine model, there was significant loss of pull-out strength with an increase in divergence from 15 degrees to 30 degrees. Therefore, attempts should be made to minimize divergence to 15 degrees or less. Lemos MJ, Jackson DW, Lee TO, et al: Assessment of initial fixation of endoscopic interference femoral screws with divergent and parallel placement. Arthroscopy 1995;11:37-41.

Several studies have shown that sitting ability by age 2 years is highly prognostic of walking. Molnar and Gordon reported that children not sitting independently by age 2 years had a poor prognosis for walking. Wu and associates reported that children sitting without support by age 2 years had an odds ratio of 26:1 of walking compared with those unable to sit. This was far higher than the odds ratios for cerebral palsy location, motor dysfunction, crawling, creeping, scooting, or rolling. Molnar GE, Gordon SU: Cerebral palsy: Predictive value of selected clinical signs for early prognostication of motor function. Arch Phys Med Rehabil 1976;57:153-158.

The exact anatomic event responsible for vocal cord paralysis associated with anterior cervical surgery remains a question. Apfelbaum and associates, in an excellent review of 900 anterior cervical surgeries, identified 30 patients with vocal cord paralysis, 3 of which were permanent. They showed that retractors placed under the longus coli for anterior cervical exposures can compress the laryngeal-tracheal branches within the larynx against the tented endotracheal tube rather than the recurrent laryngeal nerve, which is extrinsic to the larynx. By releasing the endotracheal cuff and allowing the tube to recenter itself after placement of the retractors, they were able to decrease vocal cord injury from 6.4% to 1.7%. Jewett and associates suggested that a left-sided approach may result in a lower incidence of injury. Endotracheal intubation is the second most common cause of vocal cord injury, with an incidence of approximately 2%. Apfelbaum RI, Kriskovich MD, Haller JR: On the incidence, cause, and prevention of recurrent laryngeal nerve paralysis during anterior cervical spine surgery. Spine 2000;25:2906-2912.

The radiograph shows a benign-appearing cortically based lesion eroding the underlying cortex, producing a saucer-shaped defect typical of a periosteal chondroma. The histology shows benign-appearing neoplastic cartilage. Although enchondroma would have the same histologic appearance, radiographs generally show a lesion with a central medullary epicenter. The benign-appearing histology does not support chondrosarcoma. Chondromyxoid fibroma will generally show histologic elements of its fibrous and myxoid components. Chondroblastoma typically demonstrates histologic findings of polyhedral cells separated by a chondroid matrix with pericellular, lattice-like "chicken wire" calcification. Schajowicz F: Tumors and Tumorlike Lesions of Bone: Pathology, Radiology, and Treatment, ed 2. Berlin, Springer-Verlag, 1994, pp 147-151.

The rate of revision has been found to be significantly increased in patients with a dislocated hip preoperatively compared with patients with a subluxated hip. This may be the result of compromised acetabular bone stock. The rate of nerve palsy may be increased because of the greater degree of lengthening required to reduce the reconstructed hip. Numair J, Joshi AB, Murphy JC, Porter ML, Hardinge K: Total hip arthroplasty for congenital dysplasia or dislocation of the hip: Survivorship analysis and long-term results. J Bone Joint Surg Am 1997;79:1352-1360.

The most common complication associated with tarsometatarsal joint injury is posttraumatic arthritis. In one series, symptomatic arthritis developed in 25% of the patients and half of those went on to fusion. In another series, 26% had painful arthritis. Initial treatment should consist of shoe modification, inserts, and anti-inflammatory drugs. Fusion is reserved for failure of nonsurgical management. Hardware failure may occur, but it is clinically unimportant. Kuo RS, Tejwani NC, DiGiovanni CW, et al: Outcome after open reduction and internal fixation of Lisfranc joint injuries. J Bone Joint Surg Am 2000;82:1609-1618. Arntz CT, Veith RG, Hansen ST Jr: Fractures and fracture-dislocations of the tarsometatarsal joint. J Bone Joint Surg Am 1988;70:173-181.

Full exposure of the volar plate of the proximal interphalangeal joint of the finger is best accomplished by incision of the distal C1, A3, and proximal C2 pulleys; followed by gentle retraction of the flexor digitorum superficialis and profundus tendons. Sacrifice of the A3 pulley, although associated with some biomechanic disadvantage, can be tolerated without causing functionally limiting bowstringing of the flexor tendon. Sacrifice of even a portion of the A2 or A4 pulleys can decrease the biomechanic leverage provided by the flexor tendon sheath, leading to bowstringing of the flexor tendons. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics, ed 2. Philadelphia, PA, Lippincott-Raven, 1994, pp 176-186. Strickland J: Flexor tendon-acute injuries, in Green DP, Hotchkiss RN, Pederson WC (eds): Green's Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, vol 2, pp 1853-1855.

The clinical photographs show a patient with a type I hereditary sensory motor neuropathy who has cavus feet with a flexible hindfoot. The Coleman block test shows that the hindfoot corrects into valgus. To prevent progressive cavus, patients with this condition may benefit from soft-tissue releases at a younger age while the foot is flexible. Once there is fixed deformity, combined soft-tissue and bone procedures usually are necessary. Metatarsal osteotomies will correct the cavus, but will do nothing for the drop foot. Transfer of the extensor hallucis longus to the neck of the first metatarsal and modified transfer of the extensor digitorum longus to the dorsum of the foot will prevent further claw toes and improve foot dorsiflexion. Anterior transfer of the posterior tibialis tendon will also aid in dorsiflexion. Calcaneal osteotomy should be reserved for fixed hindfoot varus that does not correct with block testing, and triple arthrodesis should be avoided as long as possible because the long-term outcome is poor. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 235-245. Coleman SS: Complex Foot Deformities in Children. Philadelphia, Pa, Lea & Febiger, 1983, pp 147-165.

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.

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.

The majority of patients with thoracolumbar burst fractures without neurologic deficit can be effectively treated with a TLSO or a hyperextension body cast. Indications for surgery are neurologic deficit and/or significant deformity (greater than 50% loss of anterior vertebral body height or marked kyphosis). Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 197-217.

As CT scanning has become available, the use of radiographs of the skull has decreased in importance for evaluation of head trauma. The indications for CT scanning for suspected head trauma include any degree of obtundation, focal neurologic deficit, history of a high-velocity injury, amnesia for the injury, progressive headache, persistent vomiting, children younger than age 2 years, serious facial injury, posttraumatic seizure, skull penetration, or a Glasgow Coma Scale score of 13 or less. Evidence of improved outcome with use of steroids in head trauma is lacking. Steroids are useful for increased intracranial pressure caused by brain tumors or abscesses. High-dose IV methylprednisolone is indicated for spinal cord trauma and improves the ultimate degree of recovery of function. When herniation is suspected in a patient with asymmetric neurologic findings or the patient's condition is deteriorating rapidly, a mannitol infusion may be used. Hall DE: Head injuries, in Hoekelman RA (ed): Primary Pediatric Care. St Louis, Mo, Mosby, 1997, pp 1709-1712. Nelson WE, Behrman RE, Kliegman RM (eds): Nelson Essentials of Pediatrics. Philadelphia, Pa, WB Saunders, 1998, p 712.

Polyethylene wear has been identified as a major contributor to failure of total knee implants, of which thickness is an important factor. Several studies have shown that the minimum thickness should be 6 to 8 mm. While Wright and Bartel have shown that 6 to 8 mm has been recommended as the minimum thickness of an ultra-high molecular weight polyethylene insert for a tibial component in total knee arthroplasty, more recent work by Meding and associates and Worland and associates has verified the clinical efficacy of 4 mm of polyethylene in compression-molded anatomic graduated nonmodular components. Bartel DL, Bicknell VL, Wright TM: The effect of conformity, thickness, and material on stresses in ultra-high molecular weight components for total joint replacement. J Bone Joint Surg Am 1986;68:1041-1051. Wright TM, Bartel DL: The problem of surface damage in polyethylene total knee components. Clin Orthop 1991;273:261-263. Meding JB, Ritter MA, Faris PM: Total knee arthroplasty with 4.4 mm of tibial polyethylene: 10-year followup. Clin Orthop 2001;388:112-117.

Both cemented and cementless total knee arthroplasties depend on adequate fixation of the tibial component to promote long-term survivorship. An effective stem and adequate peripheral fixation of the tibial component to the cancellous-cortical portion of the proximal tibia are necessary for cementless fixation. Peripheral screws and pegs can serve as adjunctive fixation to decrease micromotion and shear forces and allow bone ingrowth to occur. Careful preparation of the proximal tibial surface can minimize fixation failure. Cemented fixation of the tibial stem should be performed in addition to the plateau. Osteolysis, polyethylene wear, and failure at the insert/tray locking mechanism have not occurred. Posterior cruciate ligament retention has not caused the tibial component fixation failure.

The histology shows findings consistent with metastatic renal cell carcinoma. Renal cell carcinoma metastases are extremely vascular. Preoperative embolization helps minimize the amount of blood loss during curettage of these lesions. Chatziioannou AN, Johnson ME, Pneumaticos SG, et al: Preoperative embolization of bone metastases from renal cell carcinoma. Eur Radiol 2000;10:593-596.

The literature supports similar clinical outcomes after surgical and nonsurgical methods. The chief difference lies in the complications between the groups. Surgical patients experience more wound problems but a significantly lower rerupture rate. Although suturing the tendon allows earlier mobility, the tendon healing time is unchanged. Nonsurgical methods are less expensive to provide. Maffulli N: Rupture of the Achilles tendon. J Bone Joint Surg Am 1999;81:1019-1036. Cetti R, Christensen SE, Ejsted R, Jensen NM, Jorgensen U: Operative versus nonoperative treatment of Achilles tendon rupture: A prospective randomized study and review of the literature. Am J Sports Med 1993;21:791-799.

Ewing's sarcoma is the second most common primary sarcoma of bone in children and young adults. It is a malignant round cell tumor with uncertain histogenesis. Sheets of uniform small round blue cells with a high nuclear-to-cytoplasm ratio and the absence of osteoid formation differentiate this histologic diagnosis from the other conditions. Immunohistochemical staining and molecular diagnostic studies are useful to verify the diagnosis.

The most likely diagnosis is Lyme disease because of the patient's recent vacation in an area with a high risk of exposure. The most effective treatment is doxycycline. Neu HC: A perspective on therapy of Lyme infection. Ann NY Acad Sci 1988;539:314-316.

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.

Vascular anastamoses are exceedingly difficult with amputations distal to the nail fold as the digital vessels bifurcate or trifurcate at this level, and little functional benefit is gained compared to other means of soft-tissue coverage. Single digit amputations, other than the thumb, are a relative contraindication for replantation. Replantations at the level of the proximal phalanx lead to poor motion of the proximal interphalangeal joint. In a healthy active adult, an amputation through the wrist is an appropriate situation to proceed with a replantation. A transverse forearm amputation is a good indication with a warm ischemia time of less than 6 hours. Urbaniak JR: Replantation, in Green DP, Hotchkiss RN (eds): Operative Hand Surgery, ed 3. New York, NY, Churchill Livingstone, 1993, p 1085.

The zone of Ranvier provides the earliest increase in strength of the physis. During the first year of life, the zone spreads over the adjacent metaphysis to form a fibrous circumferential ring bridging from the epiphysis to the diaphysis. This ring increases the mechanical strength of the physis. The zone also helps the physis grow latitudinally. In turn, the increased width of the physis helps the physis further resist mechanical forces. The change in shape of the physis to its progressively more undulating form is also a factor in increasing physeal strength, but this occurs over a longer period of time, as the child's activity level increases. The undulations of the physis seen in some growth plates also add to stability but to a lesser extent. The other changes contribute little toward increasing physeal strength. Burkus J, Ogden J: Development of the distal femoral epiphysis: A microscopic morphological investigation of the zone of Ranvier. J Pediatr Orthop 1984;4:661-668.

The meniscal cartilage, like articular cartilage, possesses viscoelastic properties. The extracellular matrix is a biphasic structure composed of a solid phase (collagen, proteoglycan) that acts as a fiber-reinforced porous-permeable composite, and a fluid phase that may be forced through the solid matrix by a hydraulic pressure gradient. Although these properties are shared with articular cartilage, the meniscus is more elastic and less permeable than articular cartilage. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 3-23.

In the midforearm, the ulnar nerve travels deep to the flexor carpi ulnaris muscle and ulnar to the ulnar artery as it lies on the flexor digitorum profundus muscle. In this region, the ulnar nerve and artery lie side-by-side, whereas more proximal in the forearm, the ulnar artery originates from the brachial artery in the antecubital fossa, and the ulnar nerve lies within the cubital tunnel. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics, ed 2. Philadelphia, PA, Lippincott-Raven, 1994, pp 118-131.

The radiograph shows posttraumatic tibiofibular synostosis. This condition typically follows an eversion (high) ankle sprain that results in disruption of the interosseous membrane. Ossification usually develops within 6 to 12 months after the injury. Return to sports is possible despite the lack of normal ankle dorsiflexion and mobility between the tibia and fibula. Surgical excision is reserved for persistent pain that fails to respond to nonsurgical management once the ossification is "cold" on bone scintigraphy. Whiteside LA, Reynolds FC, Ellsasser JC: Tibiofibular synostosis and recurrent ankle sprains in high performance athletes. Am J Sports Med 1978;6:204-208. Henry JH, Andersen AJ, Cothren CC: Tibiofibular synostosis in professional basketball players. Am J Sports Med 1993;21:619-622.

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.

In childhood, the more common soft-tissue sarcomas are rhabdomyosarcoma, synovial sarcoma, and fibrosarcoma. Rhabdomyosarcoma, treated with radiation therapy and chemotherapy, is a round cell tumor and is inconsistent with this patient's histologic findings. Synovial sarcoma can be monophasic or biphasic with both spindle and epithelial-like cells and is associated with the characteristic reciprocal chromosomal translocation of t(x:18)(p11;q11) which is not found in fibrosarcoma. Synovial sarcoma also can be associated with cystic loculated areas best seen in a T2-weighted MRI scan. Nonrhabdomyosarcoma childhood soft-tissue sarcomas are treated with surgical excision in conjunction with chemotherapy and/or radiation therapy. The histology reveals no inflammatory cells to suggest an abscess; therefore, antibiotics and drainage are unnecessary. The MRI scans clearly show a mass of soft tissue and no bone involvement; therefore, proximal femoral resection is not appropriate. Serial observation is not appropriate because of the history of enlargement and insidious onset. Enzinger FM, Weiss SW: Soft Tissue Tumors, ed 3. St Louis, MO, Mosby Year Book, 1995, p 757.

Greater tuberosity anterior fractures associated with anterior glenohumeral dislocations respond very well to closed methods in the majority of patients. Closed reduction of the glenohumeral joint often anatomically reduces the greater tuberosity into its cancellous bed, without the need for open fixation or cuff repair. Once closed reduction of the joint is performed, tuberosity displacement and joint articulation should be evaluated radiographically with AP and scapular lateral views as well as an axillary view. The axillary view will not only definitively show the joint articulation but also demonstrate posterior displacement of the greater tuberosity missed on the AP and lateral views. If no or minimal (5 mm) displacement is found, then nonsurgical management consisting of a sling and gentle passive range-of-motion exercises can be instituted. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 271-286.

The patient has posttraumatic subtalar joint arthrosis that developed following a calcaneal fracture. Because there is no hindfoot deformity, in situ subtalar joint arthrodesis is the treatment of choice. Calcaneal osteotomy or distraction bone block arthrodesis is beneficial in patients with severe talar dorsiflexion or malunion of the calcaneal body. Triple arthrodesis is not warranted without changes at the transverse tarsal joint, and typically even with injury into the calcaneocuboid joint, this joint is often asymptomatic. Pantalar arthrodesis is not indicated as the pathology is occurring at the subtalar joint and not in the ankle joint. Sanders R: Fractures and fracture-dislocations of the calcaneus, in Coughlin MJ, Mann RA (eds): Surgery of the Foot and Ankle, ed 7. St Louis, MO, Mosby, 1999, pp 1422-1464. Juliano TJ, Myerson MS: Fractures of the hindfoot, in Myerson MS (ed): Foot and Ankle Disorders. Philadelphia, PA, WB Saunders, 2000, pp 1297-1340.

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.

Casali and associates provided a recent review of the treatment options for chordomas. These tumors are not radiosensitive; however, modern intensity modulated radiosurgery techniques may be of value. The combination of surgery and radiotherapy compared to surgery alone results in the same disease-free survival time. Complete surgical resection of the chondroma with clean margins offers the best survival; however, its location may make total removal impossible. Thus subtotal resection followed by radiotherapy results in better survival despite the tumor's lack of radiosensitivity.