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

Celiac sprue results in rapid gastrointestinal transit and fatty stools that impair the absorption of calcium and vitamin D and result in nutritional-deficiency osteomalacia with secondary hyperparathyroidism. The radiographs show marked osteopenia with brown tumors. A pathologic fracture is seen in the proximal humerus through a large brown tumor. Serum findings include low or normal calcium, low phosphate, elevated alkaline phosphatase, low 1,25(OH)2D, and increased PTH levels. Secondary hyperparathyroidism is associated with a variety of conditions including malabsorption syndromes. Potts JT: Parathyroid hormone: Past and present. J Endocrinol 2005;187:311-325. Corazza GR, Di Stefano M, Maurino E, et al: Bones in coeliac disease: Diagnosis and treatment. Best Pract Res Clin Gastroenterol 2005;19:453-465.

Because the patient is skeletally mature with a curve of less than 40 degrees, there is no benefit to bracing and surgery is not indicated. Management should consist of observation and follow-up radiographs in 6 months. Lonstein JE, Carlson JM: The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg Am 1984;66:1061-1071.

Early mobilization and resumption of normal activities immediately after neck sprain has been shown to improve functional outcome and decrease subjective symptoms as measured 6 months after injury. Borchgrevink GE, Kaasa A, McDonagh D, Stiles TC, Haraldseth O, Lereim I: Acute treatment of whiplash neck injuries: A randomized trial during the first 14 days after a car accident. Spine 1998;23:25-31.

The definition of brachial neuritis or Parsonage-Turner syndrome is a rare disorder of unknown etiology that causes pain or weakness of the shoulder and upper extremity. The loss of active motion excludes cervical C6-7 radiculopathy and impingement. A normal MRI scan and full passive motion exclude a rotator cuff tear and adhesive capsulitis, respectively. Misamore GW, Lehman DE: Parsonage-Turner syndrome (acute brachial neuritis). J Bone Joint Surg Am 1996;78:1405-1408.

Organisms may develop resistance to antibiotics by production of specific enzymes. S aureus develops methicillin resistance by production of penicillin-binding protein 2a (PBP2a). The strains of S aureus that have acquired the mecA gene for PBP2a are designated as methicillin-resistant S aureus (MRSA). The enzyme manifests resistance to covalent modification by beta-lactam antibiotics at the active-site serine residue in two ways. First, the microscopic rate constant for acylation (k2) is attenuated by three to four orders of magnitude over the corresponding determinations for penicillin-sensitive PBPs. Second, the enzyme shows elevated dissociation constants (Kd) for the noncovalent preacylation complexes with the antibiotics, the formation of which ultimately would lead to enzyme acylation. The two factors working in concert effectively prevent enzyme acylation by the antibiotics in vivo, giving rise to drug resistance. Catalase and oxidase are enzymes produced by some bacteria that confer virulence to the organism but do not make the organisms methicillin resistant. Glycocalix is the pericellular layer produced by bacteria that serves many functions including attachment to surfaces. Beta-lactam describes a class of antibiotics. Fuda C, Suvorov M, Vakulenko SB, et al: The basis for resistance to beta-lactam antibiotics by penicillin-binding protein 2a (PBP2a) of methicillin-resistant staphylococcus aureus. J Biol Chem 2004;279:40802-40806. Lim D, Strynadka NC: Structural basis for the beta lactam resistance of PBP2a from methicillin-resistant Staphylococcus aureus. Nat Struct Biol 2002;9:870-876.

In cementless total knee replacement, the risk of osteolysis is 30% if both components are placed without cement and screws are used for tibial fixation. The risk is 10% when a cemented tibial component is used, and the risk is 0% when both components are cemented. Loss of motion, patellofemoral pain, heterotopic bone formation, and patellar clunk are complications that can occur after cemented or cementless components are placed.

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

The floating elbow is best managed with early open reduction and internal fixation of the humeral and forearm fractures, followed by early range of motion. These fractures predispose the elbow to stiffness, and early range of motion is recommended. Solomon HB, Zadnik M, Eglseder WA: A review of outcomes in 18 patients with floating elbow. J Orthop Trauma 2003;17:563-570.

Paucytopenia is a common problem in patients with metastatic disease. Causes include chemotherapy, external beam radiation, marrow replacement by tumor, and anemia of chronic disease. There is no correlation with decreased calcium and a decrease in hematopoiesis. Supportive care with granulocyte-colony stimulating factor (G-CSF) and neupogen can stimulate hematopoiesis.

The patient will most likely exhibit ipsilateral weakness of the tibialis anterior. Gaenslen's test is designed to detect sacroiliac inflammation as a source of low back pain. Beevor's sign tests the innervation of the rectus abdominus and paraspinal musculature (L1 innervation). The extensor hallucis longus is predominantly innervated by L5. The peroneals are predominantly innervated by S1. Hoppenfeld S: Physical Examination of the Spine and Extremities. Appleton, WI, Century-Crofts, 1976.

The patient has an L5 radiculopathy secondary to an L4-5 disk herniation that is compressing the traversing L5 nerve root.

A favorable prognosis can be expected in up to 70% of children with Legg-Calve-Perthes disease who are younger than age 6 years. Containment treatment has not been shown to alter the outcome in this age group. The goals of treatment in this patient are to reduce pain (synovitis), restore motion, and improve function. Symptomatic treatment modalities include bed rest, traction, crutches, activity modification, and nonsteroidal anti-inflammatory drugs. Herring JA: The treatment of Legg-Calve-Perthes disease: A critical review of the literature. J Bone Joint Surg Am 1994;76:448-458.

An enchondroma is the most common primary tumor of the long bones of the hand. The lesion is usually asymptomatic and often is detected when there is a pathologic fracture. Shimizu K, Kotoura Y, Nishijima N, Nakamura T: Enchondroma of the distal phalanx of the hand. J Bone Joint Surg Am 1997;79:898-900.

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

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

Maffucci's syndrome is a form of enchondromatosis associated with subcutaneous and deep hemangiomas. Similar to Ollier's disease, the risk of malignant transformation of the enchondromas is much higher than that of a solitary enchondroma. Multifocal nonossifying fibromas associated with other clinical findings such as mental retardation and café-au-lait spots is known as Jaffe-Campanacci syndrome. There are two types of multifocal forms of histiocytosis: Letterer-Siwe and Hand-Schüller-Christian disease. Schwartz HS, Zimmerman NB, Simon MA, et al: The malignant potential of enchondromatosis. J Bone Joint Surg Am 1987;69:269-274. Frassica F: Orthopaedic pathology, in Miller M (ed): Review of Orthopaedics, ed 2. Philadelphia, PA, WB Saunders, 1996, pp 292-335.

The glenoid labrum receives its blood supply from the suprascapular, posterior humeral circumflex, and circumflex scapular arteries. The labral vessels arise from the capsular and periosteal vessels that penetrate the periphery of the labrum. The bone does not appear to be a source of vascularity. The posterior/superior and inferior labrum have a fairly robust vascular supply, whereas the anterior/superior labrum has relatively poor vascularity, which may influence the success of superior lateral repairs.

TFCC tears are common in athletes. As the athlete braces for a fall, the wrist is most commonly in an extended position and the forearm is pronated. Cohen MS: Ligamentous injuries of the wrist in the athlete. Clin Sports Med 1998;17:533-552.

The presence of synchronous bone disease in young patients carries a dismal prognosis, one that is even worse than the presence of resectable pulmonary metastasis. Many osteosarcomas cross the physis; therefore, this has not been shown to be of prognostic importance. Similarly, the presence of the soft-tissue mass has less prognostic significance.

The radiograph reveals developmental dysplasia of both hips. The patient has classic anterolateral undercoverage of the femoral head on the right side as demonstrated by a high acetabular index (measured at 27 degrees). Anterior undercoverage can be determined by drawing the marking for the anterior wall that fails to overlap the femoral head in this patient. Currently in North America, the most accepted surgical management for symptomatic dysplasia of the hip with good joint space is a Bernese (Ganz) periacetabular osteotomy. Surgical dislocation of the hip and femoroacetabular osteoplasty may be considered for patients with symptomatic femoroacetabular impingement of the hip. Ganz R, Klaue K, Vinh TS, et al: A new periacetabular osteotomy for the treatment of hip dysplasias: Technique and preliminary results. Clin Orthop 1988;232:26-36.

Although cervical instability is a contraindication to posterior decompression alone, segmental instability in the myelopathic cervical spine can be addressed with concomitant posterior fusion with instrumentation. Cervical lordosis represents the ideal scenario for posterior decompressive procedures for myelopathy (laminectomy and laminoplasty) because compression from anterior osteophytes, if present, is relieved as the spinal cord migrates posteriorly. The anteroposterior diameter of the spinal canal does not have an impact on the selection of surgical approach. Posterior unroofing-type procedures in kyphotic cervical spines, however, are ineffective because anterior impingement on the spinal cord will remain; therefore, kyphosis of more than 10 degrees is considered a contraindication for posterior decompression. Emery SE: Cervical spondylotic myelopathy: Diagnosis and treatment. J Am Acad Orthop Surg 2001;9:376-388.

The patient has sustained high-energy upper extremity and chest injuries. He continues to remain hemodynamically unstable with no obvious thoracic or abdominal injury responsible for bleeding. The pelvic fracture is unlikely to be causing significant bleeding. A scapulothoracic dissociation and possible disruption of one of the great vessels of the upper extremity should be considered. Evaluation of peripheral pulses or blood pressure indices bilaterally in the upper extremities is a simple way to evaluate the need for further work-up. If there is any discrepancy or further concern, angiography of the involved extremity is necessary. Althausen PL, Lee MA, Finkemeier CG: Scapulothoracic dissociation: Diagnosis and treatment. Clin Orthop 2003;416:237-244.

The triad of menstrual dysfunction, disordered eating, and stress fracture is well recognized in women who participate in endurance sports. The best treatment remains to be determined, but at present, the combination of oral contraceptives to regulate menses, an increased intake of calcium and vitamin D, as well as nutritional counseling, is the recommended treatment for decreased bone mass related to exercise-induced amenorrhea. Nattiv A, Armsey TD Jr: Stress injury to bone in the female athlete. Clin Sports Med 1997;16:197-224.

Closed kinetic chain exercises are used early in the rehabilitation process. The distal segment is fixed, and an axial load is applied which provides glenohumeral compression and reduces the demand on the rotator cuff. These exercises stimulate co-contractions of the scapular and rotator cuff muscles, load scapular stabilizers, and facilitate active motion. Facilitated active motion exercises use proximal segment motion to stimulate and facilitate motion in the target tissue. These exercises are often performed in diagonal movements. Resistive active motion exercises are used later in the rehabilitation process. These are typically open kinetic chain exercises that involve active glenohumeral motion with extrinsic loads such as weights or exercise tubing. During the later stages of upper extremity rehabilitation, plyometrics are added. These exercises help to prepare the athlete for return to sport. When performed at slower speeds, these exercises emphasize stabilization and control. As the speeds increase, muscles begin to work in the stretch-shortening sequence associated with sports participation. Garrick JG (ed): Orthopaedic Knowledge Update: Sports Medicine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 129-136.

Because the patient is essentially asymptomatic, the most appropriate course of action is observation. Prophylactic hallux valgus surgery is not medically indicated. Steroid injection would only risk infection, as well as joint and capsule damage. There are no data to support the use of a custom orthosis to delay the progression of a hallux valgus deformity. Special shoe wear or an extra-depth shoe is not necessary and is unlikely to be accepted by the patient. Donley BG, Tisdel CL, Sferra JJ, Hall JO: Diagnosing and treating hallux valgus: A conservative approach for a common problem. Cleve Clin J Med 1997;64:469-474.

The terminal branch of the posterior interosseous nerve is contained in the fourth dorsal compartment. The contents of the various dorsal wrist compartments are as follows: 1st Compartment: Abductor pollicis longus, extensor pollis brevis; 2nd Compartment: Extensor carpi radialis brevis, extensor carpi radialis longus; 3rd Compartment: Extensor pollicis longus; 4th Compartment: Extensor digitorum comminus, extensor indicus proprius, posterior interosseous nerve; 5th Compartment: Extensor digiti minimi; 6th Compartment: Extensor carpi ulnaris. The extensor indicis proprius is also contained in the fourth dorsal compartment. The extensor digiti minimi is located in the fifth dorsal compartment. The extensor carpi radialis brevis is located in the second dorsal compartment. The extensor pollicis longus is located in the third dorsal compartment, and the abductor pollicis longus is located in the first dorsal compartment. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics, ed 2. Philadelphia, PA, Lippincott-Raven, 1994, pp 150-151.

The projection of the sacroiliac joint on the outer surface of the ilium should be well understood to avoid violation of the joint during bone graft harvesting and to help in insertion of the screw across the joint. The sacroiliac joint has superior and inferior limbs. The average lengths of the superior and inferior limbs are 4.4 cm and 5.6 cm, respectively. The average width of each limb is 2.0 cm. The average distance from the longitudinal axis of the superior limb to the posterior superior iliac spine is 5.5 cm. The average longitudinal axis of the inferior limb is 1.2 cm superior to the inferior margin of the posterior inferior iliac spine. The average angle between the two axes is 93 degrees. Figure 21c most closely shows the projection of the sacroiliac joint on the outer table of the ilium. Waldrop JT, Ebraheim NA, Yeasting RA, Jackson WT: The location of the sacroiliac joint on the outer table of the posterior ilium. J Orthop Trauma 1993;7:510-513.

The radiograph shows enlargement of the bone, coarse trabeculation, a blastic appearance, and thickening of the cortex, revealing the classic appearance of Paget's disease in the sclerotic phase, the most common presentation. While lymphoma may present as a blastic lesion, it will not have the same enlargement, coarse trabeculation of bone, and the significant sclerosis seen here. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 211-215.

Simple removal of the loose glenoid component or removal of the loose component followed by implantation of a new glenoid component are both appropriate treatment choices, depending on the remaining glenoid bone stock. However, removal and reimplantation appears to provide the most predictable pain relief and better function than removal alone. Antuna SA, Sperling JW, Cofield RH, et al: Glenoid revision surgery after total shoulder arthroplasty. J Shoulder Elbow Surg 2001;10:217-224.

Open release allows lengthening of the shortened subscapularis and is preferred when there are extra-articular contractures. Arthroscopic release, combined with the use of an interscalene catheter postoperatively, is an excellent treatment for capsular contractures but is contraindicated after procedures that result in extracapsular shortening (ie, Magnuson-Stack, Putti-Platt). Additional physical therapy or manipulation under anesthesia is not likely to be helpful. Shoulder hemiarthroplasty is contraindicated with normal articular surfaces, but prosthetic arthroplasty is sometimes necessary for arthritis associated with instability or overly tight instability repairs. Harryman DT II, Matsen FA III, Sidles JA: Arthroscopic management of refractory shoulder stiffness. Arthroscopy 1997;13:133-147. Warner JJ: Frozen shoulder: Diagnosis and management. J Am Acad Orthop Surg 1997;5:130-140. Warner JJ, Allen AA, Marks PH, Wong P: Arthroscopic release of postoperative capsular contracture of the shoulder. J Bone Joint Surg Am 1997;79:1151-1158.

Hip fusion provides successful long-term results (20 to 30 years). The usual mode of failure is symptomatic arthrosis of the lower back, contralateral hip, or the ipsilateral knee. Disabling low back pain is the best indication for conversion and responds well to the procedure. Degenerative changes in the other joints do not respond as well and frequently require replacement arthroplasty. Restoration of limb length is not predictable after conversion to hip replacement. Santore RF: Hip reconstruction: Nonarthroplasty, in Callaghan JJ, Dennis DA, Paprosky WG, Rosenberg AG (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1995, pp 109-115.

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.

Onlay grafts can provide more structural support than morcellized grafts. They are more easily incorporated into the host femur than bulk segmental total femur allografts; however, the incorporation is never complete. The use of onlay grafts is principally directed at addressing segmental defects of the femur; their use can be applied with either cementless or cement fixation of the femoral stem. Emerson RH Jr, Malinin TI, Cuellar AD, Head WC, Peters PC: Cortical strut allografts in the reconstruction of the femur in revision total hip arthroplasty: A basic science and clinical study. Clin Orthop 1992;285:35-44. Pak JH, Paprosky WG, Jablonsky WS, Lawrence JM: Femoral strut allografts in cementless revision total hip arthroplasty. Clin Orthop 1993;295:172-178.

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 radiographs and history are consistent with an acute unstable slipped capital femoral epiphysis. Aronson and Loder documented an increased rate of osteonecrosis associated with manipulative reduction. They recommended bed rest with skin traction to allow the synovitis to resolve, followed by in situ pinning. They noted, however, that many of these slips reduced with anesthesia and positioning on a fracture table. Biomechanic studies have shown a slight increased resistance to shear stress when two screws are used, but it is unknown if this is significant in the clinical setting. Open epiphyseodesis does not provide postoperative stability; therefore, adjunctive fixation or immobilization is required. Numerous studies have noted the inadvisability of using multiple screws. Casting has a high rate of complications, including chondrolysis and progression of the slip. Aronson DD, Loder RT: Treatment of the unstable (acute) slipped capital femoral epiphysis. Clin Orthop 1996;322:99-110. Karol LA, Doane RM, Cornicelli SF, Zak PA, Haut RC, Manoli A II: Single versus double screw fixation for treatment of slipped capital femoral epiphysis: A biomechanical analysis. J Pediatr Orthop 1992;12:741-745.

Recent in vivo and in vitro experiments demonstrate that immobilization of tendon decreases its tensile strength, stiffness, and total weight. Microscopically, there is a decrease in cellularity, overall collagen organization, and collagen fibril diameter.

It is common for patients with ankylosing spondylitis to sustain extension-type fractures, typically near the cervicothoracic junction. These fractures can be minimally displaced, making them difficult to diagnose. In addition, the vertebral bodies are vascular and their canals are relatively enclosed, making them vulnerable to epidural bleeding. The MRI scan shows an epidural hematoma posteriorly compressing the cord. Bohlman HH: Acute fractures and dislocations of the cervical spine. J Bone Joint Surg Am 1979;61:1119-1142. Weinstein PR, Karpman RR, Gall EP, et al: Spinal cord injury, spine fracture and spinal stenosis in ankylosing spondylitis. J Neurosurg 1982;57:609-616.

The patient has a displaced four-part proximal humerus fracture. Given her age and the presence of osteopenia, a cemented hemiarthroplasty is the treatment of choice. The glenoid is uninjured so a total shoulder arthroplasty is not indicated. Percutaneous pinning in younger individuals with good bone quality may be indicated but not in an 82-year-old woman with osteopenia. Sling immobilization and immediate pendulum exercises will lead to a nonunion. Sling immobilization for 6 weeks followed by active range of motion will result in a nonunion or malunion with unacceptable functional results. Neer CS II: Displaced proximal humeral fractures: I. Classification and evaluation. J Bone Joint Surg Am 1970;52:1077-1089.

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.

Flexion contractures are the most common complication of elbow dislocations. About 15% of patients lose more than 30 degrees of flexion. The risk of contracture is proportional to the duration of immobilization. Elbows should be moved within the first few days after reduction. The splinting is for comfort and protection only while the pain subsides. Mehlhoff TL, Noble PC, Bennett JB, Tullos HS: Simple dislocation of the elbow in the adult: Results after closed treatment. J Bone Joint Surg Am 1988;70:244-249. Linscheid RL, O'Driscoll SW: Elbow dislocations, in Morrey BF (ed): The Elbow and Its Disorders, ed 2. Philadelphia, PA, WB Saunders, 1993, pp 441-452. O'Driscoll SW, Jupiter JB, King GJ, Hotchkiss RN, Morrey BF: The unstable elbow. Instr Course Lect 2001;50:89-102.

The vertebral artery traverses through the arcuate foramen after exiting the lateral aspect of C1 and before entering the skull. The foramen usually is not fully formed, but a complete foramen such as this one has been reported in up to 18% of patients. Stubbs DM: The arcuate foramen: Variability in distribution related to race and sex. Spine 1992;17:1502-1504.

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

Normal glenohumeral kinematics are represented by ball-and-socket modeling when the rotator cuff is intact. This is true for motion that involves more than 30 degrees of abduction. In patients with shoulder pain and symptomatic rotator cuff tears, superior translation occurs with abduction beyond 30 degrees. This is quite evident in massive tears but is seen consistently to a lesser degree with smaller tears. Yamaguchi K, Sher JS, Anderson WK, et al: Glenohumeral motion in patients with rotator cuff tears: A comparison of asymptomatic and symptomatic shoulders. J Shoulder Elbow Surg 2000;9:6-11.

Studies examining the impact of graded water debt have clearly shown that the magnitude of core temperature and heart rate increase accompanying work are proportional to the magnitude of water debt at the onset of exercise. Though added thermal burden from hot climates is a factor, it appears to be less significant. Latzka WA, Montain SJ: Water and electrolyte requirements for exercise. Clin Sports Med 1999;18:513-524. Montain SJ, Sawka MN, Latzka WA, et al: Thermal and cardiovascular strain from hypohydration: Influence of exercise intensity. Int J Sports Med 1998;19:87-91.

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

Brown-Sequard syndrome results from an injury to one half of the spinal cord and is characteristically seen in penetrating injuries. The spinothalamic fibers cross the midline below the level of the lesion, resulting in contralateral loss of pain and temperature sensation. The posterior columns and corticospinal tracts carry vibratory, position, and light touch sensation, as well as motor function from the ipsilateral side of the body. This results in the characteristic neurologic findings seen with Brown-Sequard syndrome. Northrup BE, Evaluation and early treatment of acute injuries to the spine and spinal cord, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia, PA, Lippincott Raven, 1998, pp 541-549.

At the ankle level, the anterior tibial artery lies medial to the EHL tendon. The artery becomes the dorsalis pedis after crossing onto the dorsum of the foot. At this point, the artery lies lateral to the tendon. Resch S: Functional anatomy and topography of the foot and ankle, in Myerson M (ed): Foot and Ankle Disorders. Philadelphia, PA, WB Saunders, 2000, vol 1, pp 25-49.

Based on the mechanism of injury and findings of medial laxity, the most likely diagnosis is injury to either the growth plate or the medial collateral ligament. With the open physeal plate, this area of injury is presumed present until proven otherwise; therefore, stress radiographs should be obtained before implementing any treatment or ordering more extensive and expensive tests. DeLee JC: Ligamentous injury of the knee, in Stanitski CL, DeLee JC, Drez D Jr (eds): Pediatric and Adolescent Sports Medicine. Philadelphia, PA, WB Saunders, 1994, vol 3, pp 406-432. Clanton TO, DeLee JC, Sanders B, Neidre A: Knee ligament injuries in children. J Bone Joint Surg Am 1979;61:1195-1201.

The radiograph reveals densities within the articular cartilage of the knee commonly referred to as chondrocalcinosis. The term chondrocalcinosis refers to the presence of calcium-containing crystals detected as radiodensities in cartilage. Calcium-containing crystals other than calcium pyrophosphate dihydrate may also deposit in articular cartilage and menisci, producing both radiographically detectable densities in cartilage and joint inflammation or degeneration. Hemochromatosis, alkaptonuria (ochronosis), and Wilson's disease are characterized by cellular deposition of iron, calcium, and copper ions, respectively, into various tissues including articular cartilage and can give this appearance. Septic arthritis does not usually cause chondrocalcinosis. Klippel JH (ed): Primer on the Rheumatic Diseases, ed 11. Atlanta, GA, Arthritis Foundation, 1997, pp 226-229 and 328-331.

The patient is showing signs of vertebral artery stroke. The signs of Wallenberg syndrome include those listed above, as well as contralateral loss of pain and temperature sensation throughout the body, an ipsilateral Horner's syndrome, dysphagia, and ataxia. Vertebral artery injuries are not unusual in significant cervical facet injuries. A lesion in the cervical spinal cord is not associated with these symptoms, and an intracranial hemorrhage from trauma is unlikely to present in this manner. Young PA, Young PH: Basic Clinical Neuroanatomy. Baltimore, MD, Williams and Wilkins, 1997, pp 242-243. Hauop JS, et al: The cause of neurologic deterioration after acute cervical spinal cord injury. Spine 2001;26:340-346.

Type 2A hangman's fractures are thought to have a flexion mechanism rather than extension and axial loading. This allows them to rotate around the anterior longitudinal ligament into flexion. Anterior translation of greater than 3 mm and angulation distinguish type 2 fractures from type 1 fractures. Although there is an association between C1 ring fractures and C2 fractures, this does not factor into the classification. If a C2-3 facet dislocation exists in combination with a C2 pars fracture, it is considered a type 3 fracture. Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 197-217.

Pitchers tend to have a decrease in internal rotation and an increase in external rotation. The increase in external rotation is felt to be multifactorial. An increase in humeral retroversion occurs from repeated throwing. This results in increased soft-tissue stretching and results in a posterior capsular contracture. Meister K, Buckley B, Batts J: The posterior impingement sign: Diagnosis of rotator cuff and posterior labral tears secondary to internal impingement in overhand athletes. Am J Orthop 2004;33:412-415.

Spontaneous swelling with the appearance of joint subluxation may be associated with an acute, subacute, or chronic bacterial infection of the sternoclavicular joint. Common causes of infection include bacteremia, rheumatoid arthritis, alcoholism, intravenous drug use, and chronic debilitating diseases. Subclavian vein catheterization and renal dialysis can predispose patients to sepsis and osteomyelitis of the sternoclavicular joint. Renoult B, Lataste A, Jonon B, et al: Sternoclavicular joint infection in hemodialysis patients. Nephron 1990;56:212-213.

The venous plexus was described by Batson and helps to explain the common distribution of metastatic cells to the vertebrae, skull, ribs, and proximal long bones. Batson studied the vertebral vein system extensively by using contrast agents in human cadavers and live monkeys. Batson's plexus is a valveless system that allows retrograde embolism from the major organs such as the breast, prostate, lung, kidney, and thyroid. It is located within the thoracoabdominal cavity and has connections to the proximal long bones and an intercommunicating network of thin-walled veins with a low intraluminal pressure. Batson OV: Function of vertebral veins and their role in spread of metastases. Ann Surg 1940;112:138-149.

The patient's right upper extremity is held in the "head waiter's" posture with the shoulder internally rotated, the elbow extended, and the wrist in flexion. The Erb type of obstetrical brachial plexus palsy involves the C5 and C6 nerve root, and occasionally, as in this child, the C7 nerve root. Obstetrical palsy is a traction injury, and is associated with a high birth weight, shoulder dystocia, cephalopelvic disproportion, or the use of forceps. Erb palsy is four times more common than injury to the entire plexus or injury to the C8 and T1 nerve roots. It results from the shoulder being depressed while the head and neck are laterally rotated, extended, and tilted in the opposite direction. Most patients recover wrist extension and elbow flexion. Patients with residual weakness of shoulder external rotation and abduction will benefit from release of the pectoralis major, latissimus dorsi, and teres major, with transfer of the latissimus dorsi and the teres major to the posterosuperior aspect of the rotator cuff. Recent studies using arthrograms and CT scans have shown a higher incidence of posterior glenoid deficiency and posterior subluxation than that observed with plain radiographs. The posterior subluxation or dislocation can be effectively reduced by tendon release and transfer procedures. Hoffer MM, Phipps GJ: Closed reduction and tendon transfer for treatment of dislocation of the glenohumeral joint secondary to brachial plexus birth palsy. J Bone Joint Surg Am 1998;80:997-1001. Pearl ML, Edgerton BW: Glenoid deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am 1998;80:659-667.

Glassman and associates reported a significantly higher pseudarthrosis rate when ketorolac was used postoperatively compared to a similar group of patients who were not given ketorolac. Animal studies from the same institution support these clinical findings. To reduce narcotic dosage, nonsteroidal anti-inflammatory drugs (NSAIDs) have been promoted as an adjunct for postoperative analgesia in patients undergoing spinal fusion. However, a high failure rate of arthrodesis has been associated with postoperative use of NSAIDs. The analgesics oxycodone hydrochloride, hydrocodone/acetaminophen, and tramadol, as well as the tricyclic antidepressant imipramine, have not been shown to inhibit fusion. Glassman SD, Rose SM, Dimar JR, et al: The effect of postoperative nonsteroidal anti-inflammatory drug administration on spinal fusion. Spine 1998;23:834-838.

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 player's symptoms represent more than the mere "burner syndrome," which leads to unilateral symptoms that typically last less than 1 minute. Return to play following a burner is allowed following nonsurgical management and once the symptoms have subsided and the player exhibits normal strength and motion of the neck and upper extremities. This player has the history, symptoms, and examination findings that are consistent with cervical neurapraxia. Return to play in contact sports is contraindicated with bilateral symptoms prior to MRI evaluation of the cervical spine. CT of the brain is indicated with a history of loss of consciousness or other symptoms suggestive of a concussion. Torg JS, Sennett B, Pavlov H, et al: Spear tackler's spine: An entity precluding participation in tackle football and collision activities that expose the cervical spine to axial energy inputs. Am J Sports Med 1993;21:640-649. Torg JS: Cervical spinal stenosis with cord neurapraxia and transient quadriplegia. Sports Med 1995;20:429-434.

The patient has a degenerative collapse of the midfoot through the tarsometatarsal joints with significant forefoot abduction; therefore, a midfoot arthrodesis is required to address the arthritic joints and deformity at the tarsometatarsal articulation. All of the other procedures correct hindfoot deformities and therefore would not be appropriate treatment. Brage M: Degenerative joint disease of the midfoot. Foot Ankle Clin 1999;4:355-367.

The Coleman block test is used to evaluate the effect of the forefoot on the rearfoot varus. If the deformity corrects with the block, then the hindfoot deformity is flexible and the varus position is secondary to the plantar flexed first ray or valgus position of the forefoot. A rearfoot orthotic will not correct the forefoot cause of the deformity. The patient still may need a lateralizing calcaneal osteotomy to realign the hindfoot. Younger AS, Hansen ST Jr: Adult cavovarus foot. J Am Acad Orthop Surg 2005;13:302-315.

The woman has early basilar thumb arthritis. An extension osteotomy will redirect the force to the dorsal, more uninvolved portion of the first carpometacarpal joint and has been reported to alleviate pain in these patients. Arthrodesis is usually reserved for young, typically male laborers. Thermal shrinkage and denervation are considered experimental at this time. Interposition arthroplasty is typically used for more advanced stages of arthritis. Tomaino MM: Treatment of Eaton stage I trapeziometacarpal disease with thumb metacarpal extension osteotomy. J Hand Surg Am 2000;25:1100-1106. Pellegrini VD Jr, Parentis M, Judkins A, et al: Extension metacarpal osteotomy in the treatment of trapeziometacarpal osteoarthritis: A biomechanical study. J Hand Surg Am 1996;21:16-23.

The pathology demonstrates a very cellular chondroid matrix with multinucleated forms, atypia, and myxomatous regions. This is most consistent with a myxoid chondrosarcoma. The radiograph shows a well-circumscribed lesion in the superior and medial aspect of the right acetabulum. The CT and MRI scans confirm these same findings with no evidence of matrix mineralization or significant surrounding edema. Unfortunately, in this location with this appearance, the radiographic differential diagnosis includes all the diagnoses listed. Terek RM: Recent advances in the basic science of chondrosarcoma. Orthop Clin North Am 2006;37:9-14. Donati D, El Ghoneimy A, Bertoni F, et al: Surgical treatment and outcome of conventional pelvic chondrosarcoma. J Bone Joint Surg Br 2005;87:1527-1530.

Poland's syndrome has four main features: 1) short digits as the result of absence or shortening of the middle phalanx; 2) syndactyly of the short digits usually consisting of a simple, complete type; 3) hypoplasia of the hand and forearm; and 4) absence of the sternocostal head of the pectoralis major on the same side. Wilson MR, Louis DS, Stevenson TR: Poland's syndrome: Variable expression and associated anomalies. J Hand Surg 1988;13:880-882.

Orthopaedic surgeons are often responsible for interpreting radiographs of general examinations such as the chest radiograph shown. For accurate interpretation, it is important to systematically review all of the information available on the radiograph. Using this approach, the fracture of the left proximal humerus is readily recognized. Linear air soft-tissue density at the lung periphery would suggest a pneumothorax, but this finding is not shown on the radiograph. The upper thoracic spine is well aligned. The sternoclavicular and distal clavicles are normal.

Most lesions of eosinophilic granuloma are simply observed, but larger aggressive lesions may require curettage and bone grafting. Frequently, biopsy is required to rule out a malignant diagnosis. The differential diagnosis of eosinophilic granuloma is osteomyelitis, Ewing's sarcoma of bone, or osteogenic sarcoma. The biopsy alone can be followed by spontaneous resolution. In some patients, low-dose radiation therapy is used. Chemotherapy or amputation is not indicated for these benign lesions.

A true compression fracture is a single-column injury that does not create canal compromise. A burst fracture is a two- or three-column injury that disrupts the middle column and thereby narrows the spinal canal. This patient has a burst fracture. The mechanism of injury is usually vertical compression or flexion compression. Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 197-217.

The radiographs show a benign-appearing, well-defined lytic lesion with a thin rim of surrounding reactive bone. The photomicrograph shows spindle cells with a myxoid cartilaginous matrix. These findings are diagnostic of chondromyxoid fibroma. This is a rare, benign tumor that usually causes pain and can be locally aggressive. Lersundi A, Mankin HJ, Mourikis A, et al: Chondromyxoid fibroma: A rarely encountered and puzzling tumor. Clin Orthop Relat Res 2005;439:171-175.

Soft-tissue sarcomas most frequently metastasize to the lung, but certain histologic types have a predilection for the lymph node system as well. Rhabdomyosarcoma, clear cell sarcoma, epithelioid sarcoma, and synovial sarcoma are four of the most common types to spread in this fashion. Careful evaluation and/or sentinel lymph node biopsy plays a role in disease staging and prognosis. Riad S, Griffin AM, Liberman B, et al: Lymph node metastasis in soft-tissue sarcoma in an extremity. Clin Orthop Relat Res 2004;426:129-134.

Excessive flexion gap tightness can be addressed with a variety of techniques; including: (a) recess and release the posterior cruciate ligament; (b) resect a posterior slope in the tibia; (c) avoid an oversized femoral component that moves the posterior condyles more distally; (d) resect more posterior femoral condyle and use a smaller femoral component placed more anteriorly; and (e) release the tight posterior capsule and balance the collateral ligaments.

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.

Congenital anomalies of the spine, including failure of formation and failure of segmentation, are associated with other anomalies in other organ systems that develop at the same time. These include anomalies in the genitourinary system, cardiac anomalies, Sprengel's deformity, radial hypoplasia, and gastrointestinal anomalies including imperforate anus and trachealesophageal fistula. Spinal dysraphism is the most common associated abnormality. McMaster found an 18% incidence before the common use of MRI. Bradford and associates reported on 16 of 42 patients with congenital spinal anomalies and spinal dysraphism using MRI. Neural axis lesions may be associated with visible midline abnormalities such as a hairy patch or nevus. The child has already had a cardiac and renal work-up, and based on the findings of the hairy patch and congenital vertebral anomalies, MRI of the entire spine is prudent at this time. Spinal fusion is indicated for progressive congenital scoliosis or kyphosis. Physical therapy does not affect the natural history of congenital scoliosis. McMaster MJ: Occult intraspinal anomalies and congenital scoliosis. J Bone Joint Surg Am 1984;66:588-601. Bradford DS, Heithoff KB, Cohen M: Intraspinal abnormalities and congenital spine deformities: A radiographic and MRI study. J Pediatr Orthop 1991;11:36-41.

In a normal knee, the hard subchondral bone helps to distribute loads across the joint surface. A metal-backed tibial component in total knee arthroplasty decreases the compressive stresses on the underlying, softer cancellous bone by distributing the load over a larger surface area, particularly when one condyle is loaded. Although metallic base plates also increase the tensile forces on the other condyle when one is loaded and may decrease the thickness of the polyethylene tray, these are not benefits. Compressive forces on the polyethylene tray are increased with metal backing. The conformity of the articular surfaces is not affected by metal backing of the tibial component.

The most common shoulder injury in hockey players is to the acromioclavicular joint. Early rest and control of pain and inflammation is the preferred management. Surgery is reserved for patients with significant coracoclavicular disruption that has failed to respond to nonsurgical management. Cross-chest stretches and overhead exercises may increase symptoms. A cortisone injection within the glenohumeral joint will have little effect. Nuber GW, Bowen MK: Acromioclavicular joint injuries and distal clavicle fractures. J Am Acad Orthop Surg 1997;5:11-18.

The MRI scans reveal an enlarged posterior tibial tendon, with degenerative signal within the tendon and an excessive amount of fluid in its sheath. This is a type II tear, as noted by Conti and associates, which is the most commonly seen tear. Slovenkai MP: Clinical and radiographic evaluation (Adult flatfoot: Posterior tibial tendon dysfunction). Foot Ankle Clin 1997;2:241-260.

The radiograph reveals a "bony mallet injury." As the distal phalanx is not volarly subluxated, extension splinting, similar to a classic mallet injury without bony involvement, is appropriate. If there is volar subluxation associated with a large bony fragment, surgical intervention is appropriate. Baratz ME, Schmidt CC, Hughes TB: Extensor tendon injuries, in Green DP, Hotchkiss RN, Pederson WC, et al (eds): Green's Operative Hand Surgery, ed 5. Philadelphia, PA, Elsevier, 2005, p 192.

The injury pattern is that of a burst fracture at L1 contiguous with a compression fracture at T12. There is associated kyphosis and slight spondylolisthesis of T12 on L1. Treatment of this type of burst fracture in neurologically intact patients is somewhat controversial, with at least one study demonstrating equal long-term results comparing nonsurgical treatment to surgical treatment. In this study, however, body casts were used initially in the nonsurgical group. Moreover, because this patient has multiple fractures, spinal fracture stabilization should be considered to facilitate early mobilization. Surgical stabilization and fusion via a posterior approach is the best treatment option in this patient. Anterior decompression is not necessary since the patient is neurologically intact. McLain RF, Benson DR: Urgent surgical stabilization of spinal fractures in polytrauma patients. Spine 1999;24:1646-1654. Wood K, Butterman G, Mehbod A, et al: Operative compared with nonoperative treatment of a thoracolumbar burst fracture without neurological deficit: A prospective, randomized study. J Bone Joint Surg Am 2003;85:773-781.

A thoracotomy in an adult with idiopathic scoliosis causes a reduction in pulmonary function that often does not return to preoperative levels. What pulmonary function that does recover, recovers over many months. Long-term improvement in pulmonary function, compared to preoperative function, is rarely seen. This should be considered in planning surgical intervention in adults with scoliosis. Graham EJ, Lenke LG, Lowe TG, et al: Prospective pulmonary function evaluation following open thoracotomy for anterior spinal fusion in adolescent idiopathic scoliosis. Spine 2000;25:2319-2325.

The radiograph shows a pathologic fracture through a unicameral (simple) bone cyst (UBC). This is the most common location and presentation of a UBC. Less than 10% of UBCs heal spontaneously following a fracture. Urgent biopsy is not indicated because the lesion appears benign and the histology of fracture callus may be misinterpreted as osteosarcoma. After the fracture heals with the use of a sling and swathe, the UBC may be treated with a minimally invasive procedure such as injection of bone marrow and/or demineralized bone matrix. The chance for success is relatively low in an active cyst located adjacent to the physis. More invasive procedures, such as curettage, Rush rod fixation, or cannulated screw decompression, have been described but are rarely necessary for treatment of upper extremity cysts. Rougraff BT, Kling TJ: Treatment of active unicameral bone cysts with percutaneous injection of demineralized bone matrix and autogenous bone marrow. J Bone Joint Surg Am 2002;84:921-929. Robosch A, Saraph V, Linhart WE: Flexible intramedullary nailing for the treatment of unicameral bone cysts in long bones. J Bone Joint Surg Am 2000;82:1447-1453.

These are classic findings of osteonecrosis of the hip. The radiograph reveals the subchondral sclerotic pattern commonly seen in osteonecrosis and is quite extensive in this patient. The MRI scan reveals the typical serpentine-like region of low signal intensity with a central zone where the signal is similar to fat. Resnick D (ed): Diagnosis of Bone and Joint Disorders. Philadelphia, PA, WB Saunders, 2002, pp 3160-3162.

Rheumatoid arthritis is an inflammatory arthritis that usually involves multiple joints. Radiologic findings of periarticular erosion, osteopenia, and minimal osteophyte formation favor rheumatoid arthritis over osteoarthritis. Pigmented villonodular synovitis and Charcot arthropathy are more often considered monoarticular diseases. There are no radiographic findings of Paget's disease.

Fractures of the hook of the hamate frequently are not identified in the acute phase. Because the fracture can be difficult to see on plain radiographs, the lack of findings can lead to a painful nonunion. A carpal tunnel view may show the fracture, but a CT scan will best detect the injury. Immobilization is the treatment of choice and will result in union in most patients unless the diagnosis is delayed. However, excision of the fragment may be necessary for patients who have nonunion, persistent pain, or ulnar nerve palsy. Carroll RE, Lakin JF: Fracture of the hook of the hamate: Acute treatment. J Trauma 1993;34:803-805.

A complete answer necessarily includes the means and standard deviations of bone mineral density in both groups. Given these, which are the basic results of the study, the P-value can be calculated if desired. All of the other options preclude assessment of the actual data, that is, the information collected by the study. P-values and confidence intervals should be perceived as additional information, which help to assess the certainty of relating the study's findings to the general population, but they should not be reported instead of the results (ie, the means and standard deviations).

The patient has aseptic loosening of the original semiconstrained prosthesis and significant proximal ulnar bone destruction; therefore, the treatment of choice is revision arthroplasty using a semiconstrained design. Although orthotic stabilization could be used, it will not provide long-term pain relief. Resection arthroplasty after removal of the components may lead to painful instability. Elbow arthrodesis would be difficult with the bone stock loss and is not considered the best option. Two main contraindications to the use of an unconstrained prosthesis are significant bone loss and previous use of a hinged or semiconstrained prosthesis. An ulnar allograft could be combined with the use of a semiconstrained long-stemmed ulnar prosthesis as a treatment modification. Ewald FC, Simmons ED Jr, Sullivan JA, et al: Capitellocondylar total elbow replacement in rheumatoid arthritis: Long-term results. J Bone Joint Surg Am 1993;75:498-507.

Isolated split posterior tendon transfer alone is best performed in a patient with cerebral palsy who is between the ages of 4 and 7 years and has a flexible equinovarus foot. Rigid deformities often must be managed with a combination of soft-tissue and bony procedures. Patients with out-of-phase activity may be best managed with a transfer of the posterior tibialis to the dorsum of the foot, while those with continuous activity are better candidates for an isolated split posterior tendon transfer. Drennan JC (ed): The Child's Foot and Ankle. New York, NY, Raven Press, 1992, pp 291-294. Green NE, Griffin PP, Shiavi R: Split posterior tibial-tendon transfer in cerebral palsy. J Bone Joint Surg Am 1983;65:748-754.

Because of the long disease-free interval, it cannot be assumed that this is breast cancer. The lesion could represent metastasis from a new primary tumor or could itself be a primary tumor. CT-guided biopsy will most effectively identify the lesion and guide treatment options. Depending on the specific diagnosis, any of the other options may be appropriate.

The MRI scan shows a rupture of the patellar tendon. This injury is most appropriately addressed with primary repair. For athletic individuals, the results of nonsurgical management are suboptimal. Reconstructive procedures are not necessary. Matava MJ: Patellar tendon ruptures. J Am Acad Orthop Surg 1996;4:287-296.

Fractures of the lateral process of the talus in snowboarders have been thought to result from pure dorsiflexion, inversion, and axial loading. In a cadaveric study, 10 cadavers were placed in fixed dorsiflexion and inversion with an axial load. This was combined with or without external rotation. No fractures occurred after axial loading in the dorsiflexed-inverted position. Fractures of the lateral process of the talus occurred in 75% of the specimens with the addition of external rotation. Boon AJ, Smith J, Zobitz ME, et al: Snowboarder's talus fracture: Mechanism of injury. Am J Sports Med 2001;29:333-338.

The patient has a chronic ingrown nail on his great toe, which is not an uncommon occurrence in teenagers because of improper nail care. There is local infection and a foreign body reaction because of the nail. Continued conservative management with soaks and antibiotics will not improve the clinical situation. In the presence of local chronic infection, nail matrix ablation is contraindicated. Additionally, in the absence of a history of an ingrown nail, a nail matrix ablation is not medically indicated. The appropriate treatment is partial removal of the nail plate. With nail plate removal, the inflammation and local infection will resolve rapidly. Pettine KA, Cofield RH, Johnson KA, Bussey RM: Ingrown toenail: Results of surgical treatment. Foot Ankle 1988;9:130-134.

The most likely diagnosis is postpolio syndrome, which is characterized by increasing weakness in both the paretic and previously normal muscles. Fatigability, joint pain, muscle atrophy, respiratory insufficiency, dysphagia, and sleep apnea are also seen. Gentle exercise and modification in lifestyle demands are generally recommended. Vigorous rehabilitation is likely to be detrimental in this condition. Further diagnostic work-up is not indicated at this time. Dalakas MC, Elder G, Hallett M, et al: A long-term follow-up study of patients with post-poliomyelitis neuromuscular symptoms. N Eng J Med 1986;314:959-963.

Posterolateral rotatory instability (PLRI) of the elbow represents a three-dimensional injury pattern of rotational displacement of the ulna from the trochlea and the radius from the capitellum. The ulna supinates (externally rotates) past its normal limit and the radiocapitellar joint subluxates posterolaterally, permitting the coronoid process to slide beneath the trochlea. In cadaver studies, the lateral ulnar collateral ligament has been shown to be the essential lesion responsible for PLRI. The medial collateral ligament (of which the anterior bundle is the most important) is the primary restraint to valgus instability. The posterolateral capsule and radial collateral ligament may be disrupted in a complete posterolateral dislocation but are not essential injuries for PLRI. The primary function of the annular ligament is to stabilize the proximal radioulnar joint. O'Driscoll SW, Jupiter JB, King GJW, Hotchkiss RN, Morrey BF: The unstable elbow. J Bone Joint Surg Am 2000;82:724-738. Olsen BS, Sojbjerg JO, Dalstra M, Sneppen O: Kinematics of the lateral constraints of the elbow. J Shoulder Elbow Surg 1996;5:333-341.

The patient has chronic tibial osteomyelitis that is due to low virulent bacteria. The history and studies do not suggest the need for an amputation or a free-flap procedure. This is a localized tibial infection that is in a healed bone; there is no need to resect the entire area of the tibia bone around the infection. The most appropriate treatment is curettage, debridement of nonviable bone, and placement of absorbable antibiotic beads, followed by a course of IV antibiotics from 1 to 4 weeks and a 6-week course of oral antibiotics. Studies have shown that in cases of localized osteomyelitis that are of low virulence, as little as 1 week of IV antibiotics followed by 6 weeks of oral antibiotics is successful. Patzakis MJ, Zalavras CG: Chronic posttraumatic osteomyelitis and infected nonunion of the tibia: Current management concepts. J Am Acad Orthop Surg 2005;13:417-427.

Retrovascular cords are common in Dupuytren's disease and commonly require surgical treatment. Nerve injury in Dupuytren's surgery is an infrequent complication that occurs partly because the digital nerves can be displaced from their normal anatomic relationships by retrovascular cords. The nerves are displaced superficially, toward the center of the digit (palmarly and ulnarly). This displacement is typically seen at the level of the metacarpophalangeal joint.

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

Osteochondritis dissecans of the capitellum is seen most commonly in adolescent athletes. It should be distinguished from osteochondrosis of the capitellum (Panner's disease), a self-limiting condition seen in younger patients. Lesions are graded I through V based on radiographic and arthroscopic appearance. Grade I lesions show intact but soft cartilage. Grade II lesions show fissuring of the overlying cartilage. Grade III lesions show exposed bone or an attached osteoarticular flap that is not loose. Grade IV lesions show a loose but nondisplaced osteoarticular flap. Grade V lesions show a displaced fragment. Simple excision of the loose osteoarticular flap is the treatment of choice for grade IV and V lesions. More complex procedures such as drilling of the in situ lesion, bone grafting, or internal fixation are associated with significantly worse results. While some authors advocate abrasion chondroplasty, the long-term benefits of the procedure are yet to be proven. Baumgarten TE: Osteochondritis dissecans of the capitellum. Sports Med Arthroscopy Rev 1995;3:219-223.

Acetabular component loosening has been reported as the most common mode of failure following total hip arthroplasty in patients with a previous acetabular fracture. Following acetabular fracture and subsequent open reduction and internal fixation, the bone quality and vascularity are compromised, thus reducing the success rate of acetabular component cementless fixation. Jimenez ML, Tile M, Schenk RS: Total hip replacement after acetabular fracture. Orthop Clin 1997;28:435-446.

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

The laboratory findings are typical for rickets. Oncogenic rickets is a paraneoplastic syndrome that results from a substance secreted by the tumor that interferes with renal tubule reabsorption of phosphate. This substance previously had been called phosphatonin but recently has been identified as fibroblast growth factor 23. Nutritional rickets is rare in developed countries. Delayed onset familial hypophosphatemic rickets is possible, but the likelihood of having two rare diseases is unlikely. Osteosarcoma does not sequester calcium. Alkaline phosphatase levels can be elevated in osteosarcoma but does not cause muscle weakness. Tumor cachexia would occur only with advanced metastatic disease. A unilateral sacral mass would not cause a bilateral L5 neuropathy or the abnormal laboratory findings. Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 29-2001. A 14-year-old with abnormal bones and a sacral mass. N Engl J Med 2001;345:903-908.

Passing the 70-degree arthroscope through the intercondylar notch provides excellent visualization of the posteromedial corner of the knee. This view should be part of every knee arthroscopy because these structures are often not well visualized from the anterior portals. If this view is omitted, tears of the peripheral posterior horn of the medial meniscus can be overlooked. The arrow points to the peripheral aspect of the posterior horn of the medial meniscus. With an intact medial meniscus, the medial tibial plateau should not be seen from this view. The semimembranosus and gastrocnemius tendons are extra-articular and not visualized. Miller MD: Basic arthroscopic principles, in DeLee JC, Drez D Jr, Miller MD (eds): Orthopaedic Sports Medicine, ed 2. Philadelphia, PA, Saunders, 2003, pp 224-237.

The patient has lumbar spinal stenosis and the MRI scans reveal the pathology at L4-5, which is secondary to posterior disk bulging and hypertrophy and infolding of the ligamentum flavum, as well as degenerative facet arthrosis. The degree of spinal stenosis is moderate and his symptoms are positional in nature. Tadokoro and associates reported on a prospective study of 89 patients older than 70 years of age who underwent nonsurgical management for lumbar spinal stenosis. They found the prognosis to be relatively good with patients scoring at "excellent" or "good" for activities of daily living at final follow-up. However, they did note that patients with a complete block on myelography did not respond favorably to nonsurgical management. Amundsen and associates reported on a 10-year prospective study comparing surgical care to nonsurgical management. They concluded that, while the long-term results largely favored surgical treatment, more than half of the nonsurgically managed patients had a satisfactory outcome. They also concluded that a delay of surgery for some months did not worsen the prognosis. Therefore, their recommendation was for an initial primarily nonsurgical approach. Amundsen T, Weber H, Nordal HJ, et al: Lumbar spinal stenosis: Conservative or surgical management? A prospective 10-year study. Spine 2000;25:1424-1435. Hilibrand AS, Rand N: Degenerative lumbar stenosis: Diagnosis and management. J Am Acad Orthop Surg 1999;7:239-249.

Pelvic osteotomies that redirect hyaline cartilage over the femoral head offer the potential for long-term preservation of the hip; however, salvage procedures such as the Chiari osteotomy are indicated in patients without a concentrically reducible hip. Ito and associates reported that moderate dysplasia and moderate subluxation without complete obliteration of the joint space and a preoperative center-edge angle of at least minus 10 degrees are desirable selection criteria. Ohashi H, Hirohashi K, Yamano Y: Factors influencing the outcome of Chiari pelvic osteotomy: A long-term follow-up. J Bone Joint Surg Br 2000;82:517-525.