100 Orthopedic MCQs: Trauma, Spine & Sports Medicine | Comprehensive AAOS/ABOS Review

The patient has a dynamic varus deformity secondary to spasticity of the tibialis anterior during stance phase with inverter/everter imbalance. The patient still has active motion of the tibialis anterior; therefore, an out-of-phase posterior tibial tendon transfer should not be performed. The same is true of the Bridle procedure. Transfer of the posterior tibialis in this patient may also result in subsequent planovalgus deformity. Lengthening of the Achilles tendon through a percutaneous tenotomy will restore dorsiflexion and decrease clonus from the stretch response. If adequate dorsiflexion is not obtained intraoperatively, then posterior tibialis tendon lengthening may be considered. A split tibialis anterior tendon transfer to the lateral cuneiform, or, transfer of the entire tendon to the cuneiform should correct the varus component and compensate for the weakened peroneals. Yamamoto H, Okumura S, Morita S, et al: Surgical correction of foot deformities after stroke. Clin Orthop Relat Res 1992;282:213-218. Piazza SJ, Adamson RL, Moran MF, et al: Effects on tensioning errors in split transfers of tibialis anterior and posterior tendons. J Bone Joint Surg Am 2003;85:858-865.

Linazolid is the first agent of the oxazolidinone group of antibiotics and is very active against methicillin-sensitive Staphylococus aureus, S epidermidis, and vancomycin-resistant enterococci. The drug has no gram-negative activity. Linazolid inhibits protein synthesis by blocking formation of the 70S ribosomal translation complex. This mechanism of action is unique to the oxazolidinones. Rybak MJ, Cappelletty DM, Moldovan T, et al: Comparative in vitro activities and postantibiotic effects of the oxazolidinone compounds eperezolid (PNU-100592) and linezolid (PNU-100766) versus vancomycin against Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus faecalis, and Enterococcus faecium. Antimicrob Agents Chemother 1998;42:721-724.

The radial head is an important secondary stabilizer of the elbow, helping to resist valgus forces. There has been a movement toward open reduction and internal fixation of the radial head when technically feasible, especially in a relatively high-demand athlete or laborer. The examination and radiograph suggest that displacement of the fragment is great enough to create a mechanical block. Extended splinting would only serve to encourage arthrofibrosis. Early range of motion is appropriate if there is minimal displacement of the radial head fragement, it is stable, and there is no mechanical block to motion. Fragments larger than one third of the joint surface should be excised only if it is not possible to reduce and repair the fragment. Primary excision of the radial head should be avoided if possible. Complications after excision of the radial head include muscle weakness, wrist pain, valgus elbow instability, heterotopic ossification, and arthritis. Hotchkiss RN: Displaced fractures of the radial head: Internal fixation or excision? J Am Acad Orthop Surg 1997;5:1-10.

A Keller proximal phalanx resection procedure usually results in reduced weight bearing under the first ray because of shortening of the toe and disruption of intrinsic flexor function. This can be an effective method of offloading a neuropathic ulcer under the great toe at the interphalangeal or metatarsophalangeal joint area. However, these features are generally undesirable in young active patients. The procedure has a high rate of recurrent deformity in patients with rheumatoid arthritis. It would exacerbate transfer metatarsalgia in a patient with a hypermobile first ray. Lin SS, Bono CM, Lee TH: Total contact casting and Keller arthroplasty for diabetic great toe ulceration under the interphalangeal joint. Foot Ankle Int 2000;21:588-593.

Because the man is only recently removed from his injury and is judged capable of returning to work with some restrictions, the term that best describes his work status is temporary partial disability.

In a relatively young patient who is an avid tennis player, the treatment of choice is a joint preserving procedure. The radiographs reveal varus alignment with loading of the medial compartment. After all nonsurgical management options have been used, the best treatment option is a medial opening wedge osteotomy. A lateral closing wedge osteotomy of the proximal tibia is also a reasonable option, but it is not one of the choices. A unicompartmental arthroplasty or a total knee arthroplasty would place significant restrictions in this patient. A unispacer may be a temporizing procedure but is controversial and without substantial data in the literature. The knee arthroscopy will not address the medial compartment osteoarthritis. Nagel A, Insall JN, Scuderi GR: Proximal tibial osteotomy: A subjective outcome study. J Bone Joint Surg Am 1996;78:1353-1358. Rinonapoli E, Mancini GB, Corvaglia A, et al: Tibial osteotomy for varus gonarthrosis: A 10- to 21-year followup study. Clin Orthop 1998;353:185-193.

Despite the relatively few problems with porous-coated cementless stems, stress shielding and thigh pain do occur. One design feature of proximally coated stems that has been associated with a higher incidence of distal osteolysis is the presence of noncircumferential proximal porous coating. Tapered, modular with sleeve, and hydroxyapatite proximally porous-coated stems have all performed well. Fully porous-coated straight stems have a high survivorship rate as well. Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 175-180. Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 417-451.

Scapular body fractures in children are rare and are often associated with other injuries of the chest and thorax. Management is generally nonsurgical, unless the injury is open, and usually consists of support with a sling and gentle range-of-motion exercises to minimize shoulder stiffness. Green N, Swiontkowski M: Skeletal Trauma in Children, ed 2. Philadelphia, PA, WB Saunders, 1998, vol 3, pp 319-341.

The area indicated by the arrow represents gadolinium contrast extending into a separation between the lateral labrum and its acetabular attachment. This can be a traumatic detachment, but occasionally a cleft may be present as a normal variant of the labral morphology. The capsular attachment of the iliofemoral ligament is peripheral to the labrum. The pulvinar is the common name applied to the fat and overlying synovium contained within the acetabular fossa above the ligamentum teres. The zona orbicularis is a circumferential thickening of the capsule around the femoral neck, and the retinacular vessels travel within the capsular synovium up the femoral neck to supply the femoral head. Petersilge CA, Haque MA, Petersilge WJ, Lewin JS, Lieberman JM, Buly R: Acetabular labral tears: Evaluation with MR arthrography. Radiology 1996;200:231-235. Czerny C, Hofmann S, Neuhold A, et al: Lesions of the acetabular labrum: Accuracy of MR imaging and MR arthrography in detection and staging. Radiology 1996;200:225-230.

Gaucher's disease is characterized by macrophage accumulation of glucocerebroside that is caused by a deficiency of lysosomal enzyme glucocerebrosidase. It is an autosomal-recessive trait and is most commonly found in Ashkenazi Jews. Orthopaedic surgeons see patients with Gaucher's disease usually because of osteonecrosis of the hip. Calcium pyrophosphate is associated with pseudogout. Hydroxyproline is a breakdown product of collagen and is found in high levels in patients with Paget's disease. Homogentisic acid is associated with ochronosis (alkaptonuria). Beatty JH: Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 247-252. Goldblatt J, Sacks S, Beighton P: The orthopedic aspects of Gaucher disease. Clin Orthop 1978;137:208-214.

Nonsurgical modalities remain the mainstay for treatment of herniated disks. Spontaneous resorption of herniated disks frequently is detected by MRI. Marked infiltration by macrophages and neovascularization are observed on histologic examination of herniated disks, and the resorption is believed to be related to this process. Many cytokines such as vascular endothelial growth factor, tumor necrosis factor-alpha, and metalloproteinases have been implicated in this process, but none has been found to be singularly responsible. Haro H, Kato T, Kamori H, et al: Vascular endothelial growth factor (VEGF)-induced angiogenesis in herniated disc resorption. J Orthop Res 2002;20:409-415.

The patient has diskitis. Administration of IV antibiotics speeds resolution and minimizes recurrence. Bed rest and cast immobilization have been successfully used to treat this disorder but can be associated with prolonged recovery and frequent recurrence, even when oral antibiotics are administered. A perivertebral abscess seen in association with this condition usually resolves without surgery. Ring D, Johnston CE II, Wenger DR: Pyogenic infectious spondylitis in children: The convergence of discitis and vertebral osteomyelitis. J Pediatr Orthop 1995;15:652-660.

Recurrent posterolateral rotatory instability of the elbow is difficult to diagnose. Such instability can be demonstrated only by the lateral pivot-shift test. The cause for this condition is laxity of the ulnar part of the lateral collateral ligament, which allows a transient rotatory subluxation of the ulnohumeral joint and a secondary dislocation of the radiohumeral joint. The annular ligament remains intact, so the radioulnar joint does not dislocate. Treatment consists of surgical reconstruction of the lax ulnar part of the lateral collateral ligament. The anterior band is the most important part of the medial collateral which is lax in valgus instability of the elbow. Morrey BF: Acute and chronic instability of the elbow. J Am Acad Orthop Surg 1996;4:117-128.

Patients who are in compensated shock have normal vital signs but still have hypoperfusion of organ beds such as the splanchnic circulation due to preferential perfusion of the heart and brain. The response to this continued hypoperfusion may be the development of a systemic inflammatory response that may lead to multiple organ failure. The patients are thought to be at risk for a "primed" immune system due to the ongoing stimulation of the immune system and may have an exaggerated response to a second stimulus such as surgery or infection. Other markers of resuscitation should be used besides vital signs to determine when resuscitation has been completed. The use of temporizing fixation has been shown to lower systemic complication rates, and the infection and union rate after staged fixation is not altered. Schulman AM, Claridge JA, Carr G, et al: Predictors of patients who will develop prolonged occult hypoperfusion following blunt trauma. J Trauma 2004;57:795-800.

The anterior cruciate ligament can be visualized on an axial MRI scan as a low-signal structure lying in the lateral aspect of the intercondylar notch. Visualization in multiple planes increases the accuracy of MRI to view the anterior cruciate ligament. The posterior cruciate ligament and ligament of Wrisberg are located on the medial wall of the notch. The ligamentum mucosum is anterior to the notch, and the popliteus tendon is posterior to the lateral femoral condyle. Resnick D, Kang HS (eds): Internal Derangements of Joints: Emphasis on MR Imaging. Philadelphia, PA, WB Saunders, 1997, pp 675-699.

Of the levels given, T5 has the most narrow pedicle in anatomic studies. One study in patients with scoliosis did note that T7 on the concave side was more narrow than T5, but T7 is not listed here as a possible answer. O'Brien MF, Lenke LG, Mardjetko S, et al: Pedicle morphology in thoracic adolescent idiopathic scoliosis: Is pedicle fixation an anatomically viable technique? Spine 2000;25:2285-2293.

Spinal stabilization is the treatment of choice in patients with severe scoliosis who have progressive positioning, sitting balance, and/or hygiene problems despite maximal nonsurgical management. Pelvic rigidity and marked frontal plane deformity necessitate anterior and posterior procedures so as to maximize correction and fusion. Weinstein SL (ed): The Pediatric Spine: Principles and Practice. New York, NY, Raven Press, 1994, pp 977-997.

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.

Esler and associates evaluated the use of manipulation under anesthesia in 47 knees. Manipulation was considered when intensive physical therapy failed to increase flexion to more than 80 degrees. The mean time from arthroplasty to manipulation was 11.3 weeks, and the mean active flexion before manipulation was 62 degrees. One year later, the mean gain was 33 degrees. Definite sustained gains in flexion were achieved even when manipulation was performed 4 or more months after arthroplasty. An additional 21 patients who met the criteria for manipulation declined the procedure, and despite continued physical therapy, they showed no significant increase in knee flexion.

While all of the above may contribute to the etiology of a tibial plateau fracture following unicompartmental knee arthroplasty, the recent literature has clearly noted that pin placement for fixation of tibial resection guides is the most critical factor associated with a tibial plateau fracture following unicompartmental knee arthroplasty. Vince and Cyran suggest that fractures associated with unicompartmental knee arthroplasty might be avoidable by limiting the number and paying attention to the location of the pin holes that are created to secure the tibial resection guides. Brumby and associates suggest avoiding multiple guide pin holes in the proximal tibia for unicompartmental knee arthroplasty. They currently recommend the use of one centrally placed pin and an ankle clamp to stabilize the resection guide. Yang and associates note that a medial tibial plateau fracture in association with minimally invasive unicompartmental knee arthroplasty can be eliminated by avoiding fixation pins close to the medial tibial cortex. Brumby SA, Carrington R, Zayontz S, et al: Tibial plateau stress fracture: A complication of unicompartmental knee arthroplasty using 4 guide pinholes. J Arthroplasty 2003;18:809-812. Yang KY, Yeo SJ, Lo NN: Stress fracture of the medial tibial plateau after minimally invasive unicompartmental knee arthroplasty: A report of 2 cases. J Arthroplasty 2003;18:801-803.

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

Studies on older systems, as well as newer designs, have confirmed that metal-on-metal bearing surfaces undergo linear wear of 2 to 5 um per year. Ceramic bearing surfaces produced with recent technology perform even better, with a wear rate of 0.5 to 2.5 um per year. Clinical wear rates of metal-on-crosslinked polyethylene have not yet been determined. McKellop H, Park SH, Chiesa R, et al: In vivo wear of three types of metal on metal hip prostheses during two decades of use. Clin Orthop 1996;329:S128-S140.

To mobilize the common iliac vessels across the midline, the iliolumbar vein must be ligated. It has a short trunk and can be torn if mobilization is attempted without ligation. It is the only branch off the common iliacs (there are no arterial branches) prior to the terminal branches, the internal (hypogastric) and external iliacs. The middle sacral vessels run distally from the axilla of the bifurcation and are a factor when accessing the L5-S1 disk. Baker JK, Reardon PR, Reardon MJ, et al: Vascular injury in anterior lumbar surgery. Spine 1993;18:2227-2230.

Absolute toe pressures greater than 40 to 50 mm Hg are a good sign of healing potential. An ABI of greater than 0.45 favors healing, but indices greater than 1 are falsely positive due to calcifications in the vessels. Normal albumin is an overall indication of nutritional status. A transcutaneous oxygen level should be greater than 40 mm Hg for healing. Mizel MS, Miller RA, Scioli MW (eds): Orthopaedic Knowledge Update: Foot and Ankle 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 113-122.

Flexion contractures and angular deformities of a limb cause inaccurate limb-length measurement results with most clinical methods. A CT scanogram is more accurate than standard scanograms for determining limb length in patients with knee flexion contractures of 30 degrees or more. The cost and time necessary to complete the examinations are comparable, but the CT scanogram delivers only 20% of the radiation needed for standard scanograms. Aaron A, Weinstein D, Thickman D, Eilert R: Comparison of orthoroentgenography and computed tomography in the measurement of limb-length discrepancy. J Bone Joint Surg Am 1992;74:897-902.

The radiograph shows changes that are most consistent with Legg-Calve Perthes disease. Valgus extension osteotomy is the salvage procedure of choice in patients with late symptomatic Perthes disease with severe joint incongruity. Prerequisites for valgus extension osteotomy include an adequate range of hip adduction and proof of improved congruity in the new position. Total hip arthroplasty is not a good alternative in the young patient. Varus osteotomy would further shorten the extremity and place a flattened portion of the femoral head in the acetabulum. A prerequisite of the innominate osteotomy is a congruent reduction. Skaggs DL, Tolo VT: Legg-Calve-Perthes disease. J Am Acad Orthop Surg 1996;4:9-16.

A knowledge of the safe quadrants for screw placement for acetabular component implantation is essential when performing total hip arthroplasty. The external iliac vessels are on the inner wall of the pelvis, corresponding to the anterior superior quadrant of the acetabulum. Keating EM, Ritter MA, Faris PM: Structures at risk from medially placed acetabular screws. J Bone Joint Surg Am 1990;72:509-511.

Lateral condylar fractures are challenging to treat because of late displacement and development of a nonunion that may lead to valgus instability, pain, or tardy ulnar nerve palsy. Fractures such as this one with more than 2 mm of displacement on any radiographic view are prone to nonunion and should be stabilized. Fractures with less than 2 mm of displacement usually are stable and may be treated nonsurgically. In these patients, careful follow-up is recommended within several days of casting to check for fracture displacement. Arthrography or MRI may be helpful in these minimally displaced fractures. Fractures with an intact articular cartilage surface, such as noted on these studies, are unlikely to displace further. Finnbogason T, Karlsson G, Lindberg L, et al: Nondisplaced and minimally displaced fractures of the lateral humeral condyle in children: A prospective radiographic investigation of fracture stability. J Pediatr Orthop 1995;15:422-425. Attarian DE: Lateral condyle fractures: Missed diagnoses in pediatric elbow injuries. Mil Med 1990;155:433-434. Flynn JC: Nonunion of slightly displaced fractures of the lateral humeral condyle in children: An update. J Pediatr Orthop 1989;9:691-696.

The axillary artery commences at the first rib as a direct continuation of the subclavian artery and becomes the brachial artery at the lower border of the teres major. The arteriogram reveals a nonfilling defect in the third portion of the artery just distal to the subscapular artery. The complex arterial collateral circulation in this region often permits distal perfusion of the extremity despite injury.

At least 8 cm of the posterior aspect of the proximal region of the humeral diaphyseal cortex can be exposed through the interval between the lateral head of the triceps and the deltoid muscle. No nerves or blood vessels need to be exposed in the dissection. The deltoid muscle is innervated by the axillary nerve and the triceps muscle by the radial nerve. This is a true internervous plane.

The patient has a bilateral facet dislocation of C6-C7 with preservation of at least some neurologic function. Urgent reduction is necessary. However, because she is sedated and unable to follow commands, an MRI scan is necessary before any closed or open posterior reduction to look for an associated disk herniation. If a disk herniation is present, it must be removed prior to any reduction maneuver to prevent iatrogenic neurologic injury. It is very unlikely that this injury can be reduced with an open anterior procedure alone. Spivak JM, Connolly PJ (eds): Orthopaedic Knowledge Update: Spine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 189-199.

Necrotizing fasciitis is an aggressive and rapidly spreading soft-tissue infection, usually caused by group A beta-hemolytic Streptococcus pyogenes. Presentation is typical of a rapidly ascending cellulitis, recalcitrant to antibiotic treatment. Differentiation between cellulitis and impetigo is difficult, and success depends on a high level of suspicion. The skin and subcutaneous tissues are affected, with sparing of the muscles. Septic shock and multi-organ system failure can be fatal. Treatment is aggressive surgical debridement with broad-spectrum antibiotics. Repeat irrigation and debridement may be necessary. Hyperbaric oxygen studies have shown inconsistent results. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2003, pp 199-205.

The clinical photograph shows an acute capsulolabral avulsion from the anterior glenoid, also referred to as a Perthes-Bankart lesion. In patients who sustain an acute dislocation that requires a manual reduction, this pathologic lesion is observed with high frequency. In several research studies, it has been visualized in 80% to 95% of patients at arthroscopy. Taylor DC, Arciero RA: Pathologic changes associated with shoulder dislocations: Arthroscopic and physical examination findings in first-time, traumatic anterior dislocations. Am J Sports Med 1997;25:306-311.

The most common mechanism of injury for turf toe is a hyperextension injury to the MTP joint. The foot is typically in a dorsiflexed position with the heel raised when an external force drives the MTP joint into further dorsiflexion. The joint capsule usually tears at the metatarsal neck because its attachment is weaker there than at the proximal phalanx. Some compression injuries to the dorsal articular surface of the metatarsal head can result from extension or hyperextension. Clanton TO, Ford JJ: Turf toe injury. Clin Sports Med 1994;13:731-741.

Excessive hindfoot valgus can lead to abutment between the calcaneus and fibula. This valgus force can lead to a stress fracture of the distal fibula. Surgery may be required if an insufficiency fracture recurs despite orthotic management. Of the choices listed, a subtalar arthrodesis is most likely to achieve rebalancing of the foot at the level of the deformity. Stephens HM, Walling AK, Solmen JD, Tankson CJ: Subtalar repositional arthrodesis for adult acquired flatfoot. Clin Orthop 1999;365:69-73

After an osteoporotic vertebral compression fracture, the risk of subsequent fractures at adjacent levels increases. This is felt to be the result of a shifting of the sagittal alignment more anteriorly, putting more stress on the osteopenic vertebral bodies and their anterior cortices. Pain generally resolves with rest, but this may take weeks or months. It has been demonstrated experimentally that osteoporotic vertebral bodies are actually less stiff and weaker after a compression fracture; therefore, deformity predisposes to further deformity. The extensor musculature often fatigues over time and usually does not hypertrophy. Frontal plane deformity is a rare development. Heaney RP: The natural history of vertebral osteoporosis: Is low bone mass an epiphenomenon? Bone 1992;13:S23-S26.

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 histologic features of multiple myeloma are distinctive for this lesion. The plasma cells are round or oval and have an eccentric nucleus and prominent nucleolus. These characteristics and a clear area next to the eccentric nucleus representing the prominent Golgi center are pathognomonic for plasma cells. Lymphoma is in the differential diagnosis; the most frequent types that occur in bone are large cell or mixed small and large cell types. The histologic appearance of the specimen is not consistent with the other choices.

Multiple attempts at closed reduction, delayed surgery for proximal humeral fractures, and associated closed head injury all have been associated with a higher incidence of heterotopic ossification. Rockwood CA Jr, Matsen FA III (eds): The Shoulder. Philadelphia, PA, WB Saunders, 1998, vol 1, p 291.

The radiographs reveal osteoarthritis and proximal humeral head migration. Integrity of the rotator cuff must be questioned based on these radiographic changes. The status of the rotator cuff is the most influential factor affecting postoperative function in shoulder hemiarthroplasty. The coracoacromial ligament provides a barrier to humeral head proximal migration in the face of a rotator cuff tear. The radiographs do not indicate significant humeral head or glenoid erosion. Acromioclavicular arthritis is often asymptomatic. Iannotti JP, Norris TR: Influence of preoperative factors on outcome of shoulder arthroplasty for glenohumeral osteoarthritis. J Bone Joint Surg Am 2003;85:251-258.

The most common finding at exploration of an inappropriately placed pedicle screw is displacement of the nerve. Pedicle breach is common, ranging from 2% to 20%, but most are asymptomatic. All of the choices are possible, but in a large series conducted by Lonstein and associates, the authors reported that displacement of the root, most often medial, was the most common finding. Laceration, contusion, or transfixion usually was not seen. Spinal fluid leakage occurs less frequently and is not expected in the minimal broach illustrated. Esses SI, Sachs BL, Dreyzin V: Complications associated with the technique of pedicle screw fixation: A selected survey of ABS members. Spine 1993;18:2231-2238. Laine T, Lund T, Ylikoski M, et al: Accuracy of pedicle screw insertion with and without computer assistance: A randomised controlled clinical study in 100 consecutive patients. Eur Spine J 2000;9:235-240.

Once degenerative changes have occurred, soft-tissue procedures are not indicated. Triple arthrodesis is the treatment of choice for adult-acquired flatfoot. Isolated fusion of the subtalar or talonavicular joint will not be sufficient to correct the problem. Lutter LD, Mizel MS, Pfeffer GB (eds): Orthopaedic Knowledge Update: Foot and Ankle. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 269-282.

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.

Progressive scoliosis develops in most patients with Duchenne muscular dystrophy. The onset of spinal deformity typically follows the cessation of walking, and curves can be expected to progress about 10 degrees per year. Posterior spinal fusion with instrumentation should be performed as soon as a curve of 25 degrees or greater is documented and before deterioration of pulmonary function (a FVC of less than 30%) precludes surgery. Patients with kyphotic posture tend to progress more rapidly than those with lordotic posture. Brace treatment is contraindicated because it is not definitive and it may mask curve progression while pulmonary function is concomitantly worsening. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 635-651.

By placing the forearm at neutral rotation, as shown in Figures 43c and 43d, the distal fragment has become malrotated by 90 degrees. This is evident by the fact that the bicipital tuberosity is rotated 90 degrees to the radial styloid. Normally, it should be directly opposite (180 degrees) to the radial styloid. The correct alignment was present in the original radiographs shown in Figures 43a and 43b. Another clue to the malrotation in the postreduction radiographs is the difference in the diameters of the opposing radial shafts. To correct this rotational malalignment, the distal fragment needs to be remanipulated into supination so that it is correctly aligned with the supinated proximal radius. Evans EM: Fractures of the radius and ulna. J Bone Joint Surg Br 1951;33:548-561.

There are no red flags in the history or examination to warrant MRI. Limited bed rest (less than 3 days) has been shown to be more beneficial to early recovery compared with prolonged bed rest (more than 7 days). No data support the use of epidural or facet steroid injections for acute low back pain.

Terminal non-weight-bearing knee extension exercises from 60 degrees to 0 degrees of flexion increase anterior tibial translation. It is for this reason that this type of exercise should be avoided in the early phase of rehabilitation following anterior cruciate ligament reconstruction so as not to place a tensile strain on the graft. The other rehabilitation exercises either lead to posterior tibial translation in relation to the femur or have no significant effect on tibial translation. Grood ES, Suntay WJ, Noyes FR, et al: Biomechanics of the knee extension exercise: Effect of cutting the anterior cruciate ligament. J Bone Joint Surg Am 1984;66:725-734. Lutz GE, Palmitier RA, An KN: Comparison of tibiofemoral joint forces during open-kinetic-chain and closed-kinetic-chain exercises. J Bone Joint Surg Am 1993;75:732-739.

To define bacteria responsible for dog and cat bite infections, a prospective study yielded a median of five bacterial isolates per culture. Pasteurella is most common from both dog bites (50%) and cat bites (75%). Pasteurella canis was the most frequent pathogen of dog bites, and Pasteurella multocida was the most common isolate of cat bites. Other common aerobes included streptococci, staphylococci, moraxella, and neisseria.

Both the medial collateral ligament and the olecranon contribute to valgus stability of the elbow. Excessive olecranon resection increases the demand placed on the medial collateral ligament in resisting valgus forces during throwing. Bone removal from the olecranon should be limited to osteophytes. Garrick JG (ed): Orthopaedic Knowledge Update: Sports Medicine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 101-111.

The differential diagnosis includes septic hip and transient synovitis. Both disorders may present with a joint effusion. The increased teardrop distance and loss of range of motion implies that there is excess fluid in the joint. While the other tests can confirm this, only aspiration can characterize the fluid further, thereby indicating the etiology of the effusion. Provided there is enough fluid obtained at aspiration, the joint fluid should be sent for Gram stain, culture, cell count, glucose, and protein studies.

Cutaneous sensation to the buttock is provided by the superior, middle, and inferior cluneal nerves. The superior cluneal nerves are the lateral branches of the dorsal rami of the upper three lumbar nerves and penetrate deep fascia just proximal to the iliac crest. They pass distally to the skin of the buttock and will be injured if the exposure extends more than 8 cm anterolateral to the posterior superior iliac spine. The lateral femoral cutaneous nerve can be injured in an anterior ilium bone graft. The superior gluteal nerve or even the sciatic nerve can be injured if bone is removed from the sciatic notch or dissection is not kept subperiosteal; however, the rate of injury is far less than cluneal nerve injury. The L5 and S1 nerve roots are anterior and can be injured if the inner table bone is harvested and the dissection is not kept subperiosteal or is too medial; however, the rate of injury still is far less than cluneal nerve injury. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, pp 295-297. Hollinshead WH: Textbook of Anatomy, ed 3. Hagerstown, MD, Harper and Row, 1974, p 379. Last RJ: Anatomy: Regional and Applied, ed 6. London, England, Churchill Livingstone, 1978, p 23.

In this young patient, every attempt must be made to retain the native proximal humerus; therefore, open reduction and internal fixation should be attempted of both the articular segment and tuberosities to the humeral shaft. This is best accomplished through an open approach. Shoulder arthroplasty should be reserved for the elderly and for failed internal fixation. Ko JY, Yamamoto R: Surgical treatment of complex fractures of the proximal humerus. Clin Orthop Relat Res 1996;327:225-237.

The history is consistent with a stress fracture. Findings on the plain radiograph are marginal, but the MRI scan shows evidence of stress reaction in the medial neck of the femur (compression side). A lesion on the compression side is not normally at risk for displacement and usually can be managed nonsurgically. A bone scan would further identify the lesion but is not necessary. A skeletal survey and chest radiograph are used in staging a tumor. Radioisotope injection and guided biopsy are sometimes used for osteoid osteomas. Boden BP, Osbahr DC: High-risk stress fractures: Evaluation and treatment. J Am Acad Orthop Surg 2000;8:344-353.

When retropulsion of the posterior vertebral wall is present, nothing prohibits the cement from following the path of least resistance into the canal or from pushing a bone fragment further into the canal; most clinicians consider it a contraindication to these techniques. Patient age itself is not a contraindication as long as there are no medical contraindications to surgery. An acute fracture in a patient who remains immobile and hospitalized because of pain may be a good indication for such a technique. Prior compression fracture and older compression fractures are not contraindications, but pain relief may be less predictable. Phillips FM, Pfeifer BA, Leiberman IH, et al: Minimally invasive treatment of osteoporotic vertebral compression fractures: Vertebroplasty and kyphoplasty. Instr Course Lect 2003;52:559-567. Truumees E, Hilibrand A, Vaccaro AR: Percutaneous vertebral augmentation. Spine J 2004;4:218-229.

Fatigue from repetitive loading of the stem with the distal aspect well-fixed resulted in stem failure. If the stem had loosened, it would not have broken. Crevice corrosion occurs at a taper interface; galvanic corrosion occurs at the junction of two metals of differing electrochemical potentials, not along a uniform portion of the implant. Simon SR (ed): Orthopaedic Basic Science. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 449-486.

CT studies show that approximately 10% to 20% of patients with high-grade osteosarcoma have pulmonary metastases at diagnosis. Although not visible on current staging studies, it is believed that up to 80% of patients have micrometastatic disease that requires systemic chemotherapy. Because it is not possible to identify those patients who do not have disseminated micrometastatic disease, most patients are treated presumptively with chemotherapy. Kaste SC, Pratt CB, Cain AM, et al: Metastases detected at the time of diagnosis of primary pediatric extremity osteosarcoma at diagnosis: Imaging features. Cancer 1999;86:1602-1608.

Disk nutrition occurs via diffusion through pores in the end plates. The disk has no direct blood supply, and the anulus is not porous to allow diffusion. The dorsal root ganglion does not provide blood supply to the disc. Biyani A, Andersson GB: Low back pain: Pathophysiology and management. J Am Acad Orthop Surg 2004;12:106-115. Urban JG, Holm S, Maroudas A, et al: Nutrition of the intervertebral disc: Effect of fluid flow on solute transport. Clin Orthop 1982;170:296-302.

In examining a traditional Muslim woman, a male physician should have another woman present, and the patient's husband, if possible. Only the affected limb or area needing examination should be exposed.

The ligaments shown are the components of the lateral collateral ligament complex, and the structure indicated by the letter "A" is the radial collateral ligament. The lateral ulnar collateral ligament is the structure indicated by the letter "C" and the annular ligament is indicated by the letter "B." The transverse ligament is a component of the medial collateral ligament complex. Morrey BF: Anatomy of the elbow joint, in Morrey BF (ed): The Elbow and Its Disorders. Philadelphia, PA, WB Saunders, 1993, p 30.

The radiograph shows multiple wide physes, consistent with a diagnosis of rickets. A low serum phosphorous level and an elevated alkaline phosphatase level are the hallmarks in diagnosing familial hypophosphatemic Vitamin D-resistant rickets. Serum calcium is usually normal or low normal. This disease is inherited as an X-linked dominant trait and usually presents at age 18 to 24 months. The disease results from a poorly defined problem with renal phosphate transport in which normal dietary intake of vitamin D is insufficient to achieve normal bone mineralization. Renal tubular dysfunction is associated with urinary phosphate wasting. Treatment involves oral phosphate supplementation, which can cause hypocalcemia and secondary hyperparathyroidism. To prevent associated problems, high doses of Vitamin D are administered. While obtaining a scanogram may be clinically indicated in an associated limb-length discrepancy, and subsequent corrective surgery may be indicated, either of these choices would not be the first course of action. An orthosis may slow the progression of genu varum in this disorder but is less important than establishing the correct diagnosis to begin pharmacologic treatment. This amount of varum and tibial bowing far exceeds the normal limits of physiologic genu varum. Skeletal dysplasias usually are not associated with abnormal laboratory values. Herring JA: Metabolic and endocrine bone diseases, in Tachdjian's Pediatric Orthopaedics, ed 3. New York, NY, WB Saunders, 2002, pp 1685-1743.

The patient has a symptomatic os trigonum caused by impingement that occurs with maximal plantar flexion of the ankle in the demi-pointe or full-pointe position. Patients frequently report posterolateral pain localized behind the lateral malleolus that may be misinterpreted as a disorder of the peroneal tendon. Pain with passive plantar flexion (the plantar flexion sign) indicates posterior impingement, not a problem with the peroneal tendon. The symptoms are not characteristic of a stress fracture, nor do the radiographs show a stress fracture or an osteochondritis dissecans lesion. The os trigonum is modest in its dimensions. The incidence or magnitude of symptoms does not correlate with the size of the fragment. Large fragments may be asymptomatic, while small lesions may create significant symptoms. Marotta JJ, Micheli LJ: Os trigonum impingement in dancers. Am J Sports Med 1992;20:533-536.

The genitofemoral nerve and the sympathetic plexus consistently lie on the ventral surface of the psoas muscle. The ilioinguinal and iliohypogastric nerves are the most superior branches of the lumbar plexus and emerge along the upper lateral border of the psoas muscle traveling toward the quadratus lumborum. Both the obturator and femoral nerves are deep and lateral to the psoas muscle. Watkins RG (ed): Surgical Approaches to the Spine, ed 1. New York, NY, Springer-Verlag, 1983, p 107. Johnson R, Murphy M, Southwick W: Surgical approaches to the spine, in Herkowitz HH (ed): The Spine, ed 4. Philadelphia, PA, WB Saunders, 1992, p 1559.

Lonner and associates conducted a prospective study to determine the reliability of analysis of intraoperative frozen sections for the identification of infection during 175 consecutive revision total joint arthroplasties (142 hips and 33 knees). The mean interval between the primary arthroplasty and the revision arthroplasty was 7.3 years (range, 3 months to 23 years). Of the 175 patients, 23 had at least 5 polymorphonuclear leukocytes per high-powered field on analysis of the frozen sections and were considered to have an infection. Of these 23 patients, five had 5 to 9 polymorphonuclear leukocytes per high-powered field and 18 had at least 10 polymorphonuclear leukocytes per high-powered field. The frozen sections for the remaining 152 patients were considered negative. On the basis of cultures of specimens obtained at the time of the revision surgery, 19 of the 175 patients were considered to have an infection. Of the 152 patients who had negative frozen sections, three were considered to have an infection on the basis of the results of the final cultures. Of the 23 patients who had positive frozen sections, 16 were considered to have an infection on the basis of the results of the final cultures; all 16 had frozen sections that showed at least 10 polymorphonuclear leukocytes per high-powered field. The sensitivity and specificity of the frozen sections were similar regardless of whether an index of 5 or 10 polymorphonuclear leukocytes per high-powered field was used. Analysis of the frozen sections had a sensitivity of 84% for both indices, whereas the specificity was 96% when the index was 5 polymorphonuclear leukocytes and 99% when it was 10 polymorphonuclear leukocytes. However, the positive predictive value of the frozen sections increased significantly (P < 0.05), from 70% to 89%, when the index increased from 5 to 10 polymorphonuclear leukocytes per high-powered field. The negative predictive value of the frozen sections was 98% for both indices. At least 10 polymorphonuclear leukocytes per high-powered field was predictive of infection, while 5 to 9 polymorphonuclear leukocytes per high-powered field was not necessarily consistent with infection. Less than 5 polymorphonuclear leukocytes per high-powered field reliably indicated the absence of infection. Feldman DS, Lonner JH, Desai P, Zuckerman JD: The role of intraoperative frozen sections in revision total joint arthroplasty. J Bone Joint Surg Am 1995;77:1807-1813. Lonner JH, Desai P, Dicesare PE, Steiner G, Zuckerman JD: The reliability of analysis of intraoperative frozen sections for identifying active infection during revision hip or knee arthroplasty. J Bone Joint Surg Am 1996;78:1553-1558. Spangehl MJ, Younger AS, Masri BA, Duncan CP: Diagnosis of infection following total hip arthroplasty, in Cannon WD Jr (ed): Instructional Course Lectures 47. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 285-295.

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

The 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.

The superior ulnar collateral, inferior ulnar collateral, and posterior ulnar recurrent arteries provide consistent vascular supply to the ulnar nerve. This supply is segmental in nature. No identifiable direct anastomosis is seen between the superior ulnar collateral and the posterior ulnar recurrent arteries. The inferior ulnar collateral artery provides the only direct vascularization to the nerve and is located in the region just proximal to the cubital tunnel. The segmental nature of the blood supply to the ulnar nerve underscores the importance of its preservation during transposition.

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.

Osteochondritis dissecans occurs in the older child or adolescent (typically older than age 13 years). It involves the lateral compartment. The etiology is felt to be microtraumatic vascular insufficiency from repetitive rotatory and compressive forces. MRI typically shows separation of cartilage from the capitellum and chondral fissuring. Panner's disease is usually seen in children younger than age 10 years, involves the entire capitellar ossific nucleus, and resolves typically with no residual deformity or late sequelae. There is no evidence of ligamentous injury. Defelice GS, Meunier MJ, Paletta GA: Elbow injury in the adolescent athlete, in Altchek DW, Andrews JR (eds): The Athlete's Elbow. New York, NY, Lippincott Williams & Wilkins, 2001, pp 231-248.

Forearm rotation results from a complex interaction of osseous articulations and soft tissues including the radiocapitellar articulation, proximal and distal radioulnar joints, the interosseous membrane, and the adjacent forearm muscles. The rotation occurs around a longitudinal forearm axis extending from the center of the radial head proximally through the foveal region of the ulnar head distally. Werner FW, An KN: Biomechanics of the elbow and forearm. Hand Clin 1994;10:357-373.

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 orthosis shown is a carbon reinforced Morton's extension, and it is commonly used for hallux rigidus. It decreases motion of the first metatarsophalangeal joint and subsequently decreases pain.

The radiograph reveals an increased distance between the scaphoid and the lunate, which is indicative of scapholunate disassociation. A ring sign is also present, which represents the distal pole of the scaphoid viewed end on in a palmarly flexed position. In the acute setting, the scapholunate can be repaired. Open repair and percutaneous pinning is the treatment of choice. Dorsal capsulodesis is performed in the chronic setting if such an injury is initially missed. Cohen MS: Ligamentous injuries of the wrist in the athlete. Clin Sports Med 1998;17:533-552.

Radiographs reveal malunion of a Monteggia fracture-dislocation. Dislocation of the posterior radial head is caused by the malunited ulnar fracture. The deformity includes shortening with an apex posterior angulation. In the acute setting, open reduction of the radial head rarely is necessary; however, in chronic dislocations, open reduction is required. Without ulnar osteotomy, recurrent radial head dislocation is likely.

The first extensor compartment of the wrist typically contains a single extensor pollicis brevis tendon and the abductor pollicis longus tendon that nearly always has multiple tendon slips. The extensor pollicis brevis tendon is frequently found to be separated from the slips of the abductor pollicis longus tendon by an intracompartmental septum. During surgery, this septum must be divided to complete the release of the compartment. Jackson WT, Viegas SF, Coon TM, Stimpson KD, Frogameni AD, Simpson JM: Anatomical variations in the first extensor compartment of the wrist: A clinical and anatomical study. J Bone Joint Surg Am 1986;68:923-926.

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 MRI scan reveals a full-thickness rotator cuff tear with retraction and increased signal in the subacromial space indicating joint fluid. Herzog RJ: Magnetic resonance imaging of the shoulder. Instr Course Lect 1998;47:3-20.

Diabetes mellitus, obesity, and exposure to steroids have all been associated with the development of Achilles tendinopathy. In addition, Achilles tendinopathy has been associated with a history of hormone replacement therapy and the use of oral contraceptives. Quinolone antibiotics have also been linked to Achilles tendinopathy. Holmes GB, Lin J: Etiologic factors associated with symptomatic Achilles tendinopathy. Foot Ankle Int 2006;27:952-959.

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.

The Vancouver classifications describes periprosthetic hip fractures in the following way. Type A fractures are in the trochanteric region. Type B1 fractures occur around the stem or at the tip in the face of a well-fixed stem. These are usually treated with open reduction and internal fixation, usually including struts, cable, and/or cable plates. Type B2 fractures occur in the same region with a loose stem. Type B3 fractures occur with a loose stem where the proximal bone is of poor quality and/or severely comminuted. Type C fractures occur well below the stem. Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 149-154. Parvizi J, Rapuri VR, Purtill JJ, et al: Treatment protocol for proximal femoral periprosthetic fractures. J Bone Joint Surg Am 2004;86:8-16.

The radiographs and CT scan reveal osteoarthritis with posterior subluxation and posterior bone loss. Total shoulder arthroplasty with reaming of the high side to neutralize the glenoid surface has been shown to yield better results than hemiarthroplasty. The amount of bone loss in this patient does not require posterior glenoid augmentation. Reverse total shoulder arthroplasty is indicated for rotator cuff tear arthropathy; therefore, it is not applicable. Arthroscopic debridement has yielded poor results with advanced osteoarthritis and posterior subluxation. Results from glenoid osteotomy have been variable and glenoid osteotomy is not indicated with associated osteoarthritis. Iannotti JP, Norris TR: Influence of preoperative factors on outcome of shoulder arthroplasty for glenohumeral osteoarthritis. J Bone Joint Surg Am 2003;85:251-258.

A positive margin is most closely related to subsequent local recurrence. The other factors cited, including the size and site of the tumor, may be related to local recurrence; however, they are more commonly prognostic because of the difficulty in obtaining wide surgical margins about large or proximal tumors. Radiation therapy has been noted to decrease the incidence of recurrence but is not felt to be as important as the surgical margin. The grade of the tumor has more influence on the prevalence of metastatic disease than the incidence of local recurrence. Lewis JJ, Leung D, Heslin M, Woodruff JM, Brennan MF: Association of local recurrence with subsequent survival in extremity soft tissue sarcoma. J Clin Oncol 1997;15:646-652.

Painful incisional neuromas after bunion surgery frequently involve the dorsomedial cutaneous branch of the superficial peroneal nerve. This is the medial branch of the superficial peroneal nerve that terminates as the dorsomedial cutaneous nerve to the hallux. Branches of the deep peroneal nerve to this area are rare, and no branches to this area exist from the sural nerve. The saphenous nerve branches are generally more proximal, and the medial plantar nerve lies plantarly. Kenzora JE: Sensory nerve neuromas: Leading to failed foot surgery. Foot Ankle 1986;7:110-117.

Unicompartmental arthroplasty of the knee for single compartment arthrosis has recently become more popular. Contraindications to unicompartmental knee arthroplasty include fixed varus or valgus deformity of more than 5 degrees, restricted range of motion, fixed flexion contracture, joint subluxation of 5 mm or greater, and arthrosis of the opposite and/or patellofemoral compartment. Cossey AJ, Spriggins AJ: The use of computer-assisted surgical navigation to prevent malalignment in unicompartmental knee arthroplasty. J Arthroplasty 2005;20:29-34. Iorio R, Healy WL: Unicompartmental arthritis of the knee. J Bone Joint Surg Am 2003;85:1351-1364.

The mutation of the retinoblastoma gene has been associated with an increased prevalence of osteosarcoma. The mutation resulting in EWS-FLI1 is associated with Ewing's sarcoma. The other mutations are associated with tumor formation and proliferation but not necessarily with osteosarcoma formation. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 4. Scholz R, Kabisch H, Delling G, Winkler K: Homozygous deletion within the retinoblastoma gene in a native osteosarcoma specimen of a patient cured of a retinoblastoma of both eyes. Pediatr Hematol Oncol 1990;72:65.

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.

Suprascapular nerve palsy is a fairly uncommon yet well-known cause of shoulder pain and weakness. A variety of causes have been described, including compression by a ganglion cyst, an anomalous or thickened superior transverse scapular ligament, a humeral and scapular fracture, and traction or kinking of the nerve in the suprascapular notch. In this patient, the injury is most likely caused by traction or compression of the nerve in the suprascapular notch as the result of positioning during abdominal surgery; therefore, the studies of choice are electromyography and nerve conduction velocity studies. While MRI of the cervical spine may be of some value in ruling out a radiculopathy, the clinical history does not support such a cause for this condition. Rengachary SS, Neff JP, Singer PA, Brackett CE: Suprascapular entrapment neuropathy: A clinical, anatomical, and comparative study. Part 1: Clinical study. Neurosurgery 1979;5:441-446. Rengachary SS, Burr D, Lucas S, Hassanein KM, Mohn MP, Matzke H: Suprascapular entrapment neuropathy: A clinical, anatomical and comparative study. Part 2: Anatomical study. Neurosurgery 1979;5:447-451.

The peroneus tertius, although absent in 10% of the population, originates on the distal third of the extensor surface of the fibula and inserts onto the base of the fifth metatarsal, possibly extending to the fascia over the fourth interosseous space. The muscle is located in the anterior compartment of the leg and is innervated by the deep peroneal nerve. The tendon produces dorsiflexion and eversion when walking and can be used as an insertion point during tendon transfers to assist dorsiflexion. This tendon is peculiar to humans and is a proximally migrated deep extensor of the fifth toe. Joshi SD, Joshi SS, Athavale SA: Morphology of the peroneus tertius muscle. Clin Anat 2006;19:611-614. Williams PL, Bannister LH, Berry MM, et al (eds): Gray's Anatomy, ed 38. London, Churchill Livingston, 1995, p 883.

Giant cell tumor of the tendon sheath is the most common solid soft-tissue mass in the hand. These tumors are slow-growing and may be present for months or years before coming to medical attention. Patients usually report mechanical difficulties because of the size or position of the tumor. The gross appearance is that of a lobulated mass that may be multicolored; typically yellow, brown, red, and gray. Histologically the lesion consists of multinucleated giant cells, polygonal mononuclear cells, and histiocytes that may contain abundant hemosiderin or lipid. Walsh EF, Mechrefe A, Akelman E, et al: Giant cell tumor of tendon sheath. Am J Orthop 2005;34;116-121.

The clinical photograph shows a classic boutonniere deformity. It is likely that the patient sustained a volar dislocation of the proximal interphalangeal joint, with a concomitant rupture of the central slip insertion of the extensor tendon. Peimer CA, Sullivan DJ, Wild DR: Palmar dislocation of the proximal interphalangeal joint. J Hand Surg Am 1984;9:39-48.

Total shoulder arthroplasty yields excellent pain relief and function in patients with osteoarthritis. It is favored over humeral arthroplasty, especially when there is asymmetric posterior glenoid wear and posterior humeral subluxation as shown on the axillary radiograph. Arthroscopic debridement of the glenohumeral joint may be helpful in delaying the need for arthroplasty when the arthritic changes are mild to moderate but is not indicated for advanced osteoarthritis. Cofield RH, Frankle MA, Zuckerman JD: Humeral head replacement for glenohumeral arthritis. Semin Arthroplasty 1995;6:214-221. Levine WN, Djurasovic M, Glasson JM, Pollock RG, Flatow EL, Bigliani LU: Hemiarthroplasty for glenohumeral osteoarthritis: Results correlated to degree of glenoid wear. J Shoulder Elbow Surg 1997;6:449-454.

Bone bruises are often noted on MRI after anterior cruciate and medial collateral ligament injuries. The significance of these injuries awaits long-term follow-up studies. The areas of increased signal on T2-weighted images represent areas of acute hemorrhage and are secondary to microfractures of the adjacent medullary trabeculae. Wright RW, Phaneuf MA, Limbird TJ, et al: Clinical outcome of isolated subcortical trabecular fractures (bone bruise) detected on magnetic resonance imaging in knees. Am J Sports Med 2000;28:663-667.

Based on the radiographic findings, the patient has a metallic foreign body in her foot that is consistent with a needle. She has local infection secondary to the continued presence of the foreign body. CT is not necessary to localize the foreign body as it is adequately visualized on the plain radiographs. The infection cannot be adequately treated until the foreign body is removed. Attempted removal of foreign bodies without proper anesthesia and fluoroscopy frequently results in frustration because of the inability to localize the foreign body. Removal in a surgical suite with proper anesthesia and fluoroscopy is the preferred option. Once the foreign body is removed, the local infection will resolve rapidly. Combs AH, Kernek CB, Heck DA: Orthopedic grand rounds: Retained wooden foreign body in the foot detected by computed tomography. Orthopedics 1986;9:1434-1435.

Shufflebarger and others have reported that the placement of anterior interbody structural support at the lumbosacral junction increases the overall construct stiffness and reduces the strain on posterior instrumentation, thereby reducing the risk of screw pull-out or fracture. The stiffness of the posterior instrumentation actually increases, whereas the actual strength of the instrumentation remains the same. Actual strain measured at an adjacent intervertebral disk to a fusion construct is expected to increase. Shufflebarger HL: Moss-Miami spinal instrumentation system: Methods of fixation of the spondylopelvic junction, in Margulies JI, Floman Y, Farcy JPC, et al (eds): Lumbosacral and Spinal Pelvic Fixation. Philadelphia, PA, Lippincott-Raven, 1996, pp 381-393. Cunningham BW: A biomechanical approach to posterior spinal instrumentation: principles and applications, in DeWald RL (ed): Spinal Deformities: A Comprehensive Text. New York, NY, Thieme, 2003, pp 588-600.

A total hip arthroplasty using the posterior approach has resulted in hip dislocation under certain circumstances. Reconstruction of the external rotator/capsular complex is recognized as a stability-enhancing mechanism for the posterior approach. During the procedure, the acetabular component should be placed in 15 to 20 degrees of anteversion and approximately 45 degrees of abduction. Relative retroversion is a risk factor for posterior dislocation. High abduction angles result in edge loading of the polyethylene and possible early failure, as well as an increased risk of dislocation. Smaller diameter heads and skirted neck extensions used together decrease the range of motion that is allowed before impingement occurs, and this can result in dislocation. Shorter neck lengths generally result in soft-tissue envelope laxity. If laxity occurs, increased offset, neck length, or both can improve stability. Pellicci PM, Bostrom M, Poss R: Posterior approach to total hip replacement using enhanced posterior soft tissue repair. Clin Orthop 1998;355:224-228.

The natural history of complete developmental dislocation of the hip is dependent on two factors: bilaterality and the presence or absence of a false acetabulum. Patients with bilateral dislocations may have low back pain because of hyperlordosis, but they tend to have less disability than patients with unilateral dislocations who have secondary problems related to limb-length inequality. Degenerative joint disease and clinical disability are most likely to develop in patients with completely dislocated hips and well-developed false acetabula. In a 12-year-old child who has bilateral developmental hip dislocations, it would be difficult to obtain surgical treatment results that are better than the natural history of the disorder. Abductor strengthening exercises are unlikely to influence the long-term outcome in this disorder. Surface replacements are not indicated in young asymptomatic patients. Weinstein SL: Natural history of congenital hip dislocation (CDH) and hip dysplasia. Clin Orthop 1987;225:62-76.

The patient has a complete rupture of the posterior tibial tendon with minimal hindfoot valgus deformity. The deformity is supple, and there is no arthritis in the subtalar, talonavicular, or calcaneocuboid joints; therefore, joint-sparing procedures are appropriate in this patient (avoidance of arthrodeses). The treatment of choice is flexor digitorum longus tendon transfer, medial slide calcaneal osteotomy, and spring ligament repair. Primary repair of an incompetent posterior tibial tendon can lead to failure and recurrence of pain and deformity. Talonavicular arthrodesis corrects the forefoot abduction and elevates a plantar flexed talus; however, the patient does not have this deformity; therefore, the procedure is not indicated. Myerson MS, Corrigan J, Thompson F, et al: Tendon transfer combined with calcaneal osteotomy for treatment of posterior tibial tendon insufficiency: A radiological investigation. Foot Ankle Int 1995;16:712-718. Trnka HJ, Easley ME, Myerson MS: The role of calcaneal osteotomies for correction of adult flat foot. Clin Orthop 1999;365:50-64. Jahss MH: Spontaneous rupture of the tibialis posterior tendon: Clinical findings, tenographic studies, and a new technique for repair. Foot Ankle 1982;3:158-166.

Examination findings that show flexion of only 55 degrees at discharge should alert the surgeon that the patient will require close scrutiny and follow-up. Mauerhan and associates examined the records of 745 patients who had a primary total knee arthroplasty from 1993 to 1996. At their institution, development and implementation of clinical pathways resulted in a significant decrease in the average length of stay, beginning in 1993 with 6.4 days +/- 1.8 days and progressively decreasing to 4.4 days +/- 1.0 days in 1996. The rate of manipulation (patients manipulated at 6 weeks/total number of patients receiving total knee arthroplasty) was 6.0% in 1993, 11.3% in 1994, 13.5% in 1995, and 12.0% in 1996. In the period of 1993 to 1996, patients requiring manipulation consistently had a lower range of motion of 69.0 degrees +/- 10 degrees at the time of discharge compared with patients not requiring manipulation who had a range of motion of 80.7 degrees +/- 10.6 degrees. In this era of outpatient services, however, another solution would be to arrange for outpatient physical therapy on a more frequent basis and to see the patient more frequently in the office until an acceptable range of motion is established.

The radiographs show an elbow dislocation associated with a comminuted radial head fracture. In the setting of comminution and instability, factures of the radial head are best managed with an arthroplasty rather than open reduction and internal fixation. Resection of the radial head will worsen the instability and is not recommended. Silastic radial head replacements are contraindicated. Hildebrand KA, Patterson SD, King GJ: Acute elbow dislocations: Simple and complex. Orthop Clin North Am 1999;30:63-79.

Traumatic mydriasis occurs from a contusion to the iris sphincter. This is a transient phenomenon during which the iris fails to constrict properly, resulting in a dilated pupil. More severe trauma can result in a tear of the sphincter and permanent pupillary deformity. In association with head injury, traumatic anisocoria would be a concerning indicator of the severity of injury. Retinal detachment, lens dislocation, corneal abrasion, and traumatic hyphema are all potential results of eye injury but are not reflected by this clinical description. Brucker AJ, Kozart DM, Nichols CW, Irving MR: Diagnosis and management of injuries to the eye and orbit, in Torg JS (ed): Athletic Injuries to the Head, Neck, and Face, ed 2. St Louis, MO, Mosby Year Book, 1991, pp 650-670.

The infant has a well-positioned hip in the Pavlik harness and treatment should be continued in the current position. The success rate is over 90% with the use of this device for a dislocatable hip. Ultrasound is a useful tool to confirm appropriate positioning of the cartilaginous femoral head during treatment. If the femoral head is not reduced after 2 to 3 weeks in the harness, this mode of treatment should be abandoned. Forceful extreme abduction can cause osteonecrosis of the femoral epiphysis and should be avoided. Closed reduction, arthrography, and spica casting are indicated if the hip cannot be maintained in a reduced position with the harness. Lehmann HP, Hinton R, Morello P, et al: Developmental dysplasia of the hip practice guideline: Technical report. Committee on Quality Improvement, and Subcommittee on Developmental Dysplasia of the Hip. Pediatrics 2000;105:E57.