Pediatric Orthopedic MCQs: Hip, Spine & Trauma

Question 1

The mother of a 24-month-old girl reports that the child cannot rotate her right forearm. She also notes delayed development, with the child first walking at 18 months. The child has a five-word vocabulary and has not begun using simple phrases. Examination reveals that the right forearm is fixed in 80 degrees of pronation. The remainder of the examination of both upper extremities is otherwise normal. A radiograph is shown in Figure 41. Which of the following studies will best aid in diagnosis?

Explanation

The patient has classic radioulnar synostosis. Patients with this disorder frequently have duplication of sex chromosomes. Synostosis is often seen in females with 48-XXXX or 49-XXXXX in association with delayed development and mental retardation. In males, it can be associated with 48-XXXY or 49-XXXXY. Radioulnar synostosis is not usually associated with muscle disorders, congenital heart disease, or renal anomalies. MRI of the forearm can reveal other soft-tissue anomalies, but this information is not particularly helpful in planning therapy. Osteotomy is sometimes indicated to improve rotational position of the wrist, but this patient's rotation is quite functional for everyday tasks, and rotational osteotomy is not indicated.

Question 2

Figure 42 shows the radiograph of a patient with spinal muscular atrophy. Examination reveals good upper extremity function, and she can tie her shoes and propel a manual wheelchair. Posterior instrumentation and fusion may result in

Explanation

Spinal muscular atrophy is caused by an abnormal survival motor neuron gene that prevents apoptosis of the motor nerves. Spinal fusion results in better sitting balance, stabilized or improved pulmonary function, and high parental satisfaction, but it may result in at least temporary loss of upper extremity function. Bentley G, Haddad F, Bull TM, Seingry D: The treatment of scoliosis in muscular dystrophy using modified Luque and Harrington-Luque instrumentation. J Bone Joint Surg Br 2001;83:22-28. Furumasu J, Swank SM, Brown JC, Gilgoff I, Warath S, Zeller J: Functional activities in spinal muscular atrophy patients after spinal fusion. Spine 1989;14:771-775.

Question 3

A 2-week-old infant has had diminished movement of the right upper extremity since birth. Examination reveals weakness of shoulder abduction and external rotation, elbow flexion, and forearm supination. Both pupils are equally round and responsive to light. The remainder of the examination is normal. Radiographs of the upper limb show a healing middle-third clavicle fracture. Management should consist of

Explanation

The patient has a classic Erb's palsy with weakness of the muscles innervated by the fifth and sixth cervical roots. Horner syndrome, a poor prognostic indicator for recovery, is absent in this infant. All infants with brachial plexus birth palsies initially should be monitored for spontaneous recovery during the first 3 to 6 months of life. During this period of observation, glenohumeral motion, especially external rotation, should be maintained. Many infants will begin to show recovery within the first 6 to 8 weeks after birth and continue on to normal function. The timing of microsurgery is controversial. A recent study found that the outcome of microsurgical repair in patients who had no recovery of biceps function within 3 months after birth was similar compared to those who had recovery of biceps function between 3 and 6 months and no microsurgical repair. The author concluded that microsurgical repair was effective in improving function in those infants who had no evidence of recovery of biceps function within the first 6 months of life. Waters PM: Comparison of the natural history, the outcome of microsurgical repair, and the outcome of operative reconstruction in brachial plexus birth palsy. J Bone Joint Surg Am 1999;81:649-659.

Question 4

Progressive paralysis is most likely to be seen in association with what type of congenital vertebral abnormality?

Explanation

Anterior failure of formation results in a progressive kyphosis that may lead to cord compression and progressive neurologic deficit. Anterior failure of segmentation can also produce progressive kyphosis but usually is not severe enough to cause cord compression. Posterior failure of formation is seen in conditions such as myelomeningocele in which the neurologic deficit is generally stable. Lateral abnormalities and posterior failure of segmentation are rarely associated with progressive neurologic deficit. McMaster MJ, Singh H: Natural history of congenital kyphosis and kyphoscoliosis: A study of one hundred and twelve patients. J Bone Joint Surg Am 1999;81:1367-1383.

Question 5

A 9-year-old child has right groin pain after falling from a tree. Examination reveals that the right leg is held in external rotation, and there is significant pain with attempts at passive range of motion. Radiographs are shown in Figures 43a and 43b. Management should consist of

Explanation

The complications of femoral neck fractures in children include osteonecrosis, malunion, nonunion, and premature physeal closure. It is presumed that the risk of osteonecrosis is directly related to the amount of displacement at the time of injury and is not affected by the type of treatment. The risk of the other complications can be decreased depending on the type of treatment. Anatomic reduction by either closed or open methods can reduce the risk of malunion. The addition of internal fixation allows for maintenance of the reduction. In young children who cannot comply with a partial or non-weight-bearing status, the addition of a spica cast gives added protection. Canale ST: Fractures of the hip in children and adolescents. Orthop Clin North Am 1990;21:341-352.

Question 6

An 8-year-old boy with moderate factor VIII hemophilia played kickball earlier in the day and now reports progressively severe groin pain and is unable to walk. Examination reveals marked paresthesias over the medial aspect of the distal tibia. What is the most likely diagnosis?

Explanation

The iliacus muscle is a frequent site of hemorrhage in patients with severe or moderate hemophilia. In patients with moderate hemophilia, hemorrhage into the iliacus muscle often follows play or sporting events that include forceful contraction of the hip flexor muscles. An expanding iliacus hematoma compresses the adjacent femoral nerve, with one study reporting 60% complete femoral nerve palsy in hemophiliacs with an iliacus or iliopsoas hemorrhage. Femoral nerve compression typically includes paresthesias in the distribution of the terminal saphenous nerve branch. Hip joint hemarthrosis may occur, but this condition is not as frequent in hemophiliacs as muscle hemorrhage into the iliacus muscle. More importantly, a hip joint hemarthrosis is not associated with significant compression of the femoral nerve. Avulsion fractures of the anterior superior iliac spine typically occur during adolescence and are not associated with saphenous nerve paresthesias. Slipped capital femoral epiphysis does not have an increased association with hemophilia and usually occurs during the adolescent years. Greene WB: Diseases related to the hematopoietic system, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, pp 379-426.

Question 7

The patient shown in Figure 44 reports that her toes hurt when she walks. Management should consist of

Explanation

Brachymetatarsia is a congenital hypoplasia of one or more metatarsals. Shortening of the fourth metatarsal is the most common form of brachymetatarsia and is often bilateral. Taping and manipulative reduction attempts are ineffective, and extensor tenotomy and capsulotomy are not likely to sufficiently correct the deformity. Fusion or metatarsal lengthening result in complications and generally are not indicated. Shoe modifications, such as extra-depth or extra-wide shoes, generally will improve symptoms. If pressure and trauma persist in the older child, metatarsal lengthening or amputation may be indicated. Stevens PM: Toe deformities, in Drennan JC (ed): The Child's Foot and Ankle. New York, NY, Raven Press, 1992, p 195.

Question 8

Figures 45a and 45b show the AP and lateral radiographs of a 15-year old patient who is undergoing surgery to add 3 cm of length to the femur. Based on the radiographic findings, what is the next most appropriate step in management?

Explanation

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

Question 9

Examination of a 9-year-old boy reveals a right thoracic prominence on forward flexion. Neurologic examination is normal, and no other abnormalities are noted. AP radiographs reveal a 30-degree right thoracic curve. Initial management should consist of

Explanation

The patient has juvenile scoliosis. MRI has shown an association between juvenile scoliosis and intraspinal abnormalities, most often syringomyelia and Arnold-Chiari malformations. All juvenile curves greater than 20 degrees should be evaluated with MRI despite the absence of neurologic findings. Weinstein SL (ed): The Pediatric Spine: Principles and Practice, ed 1. New York, NY, Raven Press, 1994, pp 685-705 Nohria V, Oakes WJ: Chiari I malformation: A review of 43 patients. Pediatr Neurosurg 1990-91;16:222-227.

Question 10

A 13-year-old boy is comatose and has irregular breathing after being struck by a car while riding his bicycle. Auscultation suggests a pneumothorax on the right side and swelling about the right arm and leg. Initial management should consist of

Explanation

The first priority is to gain control of the airway with intubation. Following intubation, management should consist of ventilation and placement of a chest tube if needed, vascular access and circulatory stabilization, radiographs of the cervical spine and chest, and CT of the brain. American College of Surgeons Committee on Trauma. Advanced Trauma Life Support Course. Instructor's Manual. Chicago, IL, American College of Surgeons, 1984.

Question 11

Overgrowth of a limb in a patient with neurofibromatosis type 1 (NF1) is most likely associated with the presence of

Explanation

Plexiform neurofibromas are lesions found in patients with NF1. Clinical reports show the prevalence of plexiform neurofibroma to be 20% to 30% but increases to 40% when imaging studies are routinely obtained. The lesions are characterized by diffuse hypertrophy of the involved nerves but with preservation of the nerves' fascicular organization. The lesions may involve the dermis or may arise in the deeper structures. Palpation of a dermal lesion provokes an image of a "bag of worms." Plexiform neurofibromas may cause disfigurement and hyperpigmentation of the overlying skin. The lesions also can cause diffuse hypertrophy of the soft tissue and bone, with resultant changes ranging from a relatively minor limb-length discrepancy to gigantism of the entire extremity. Dural ectasia is frequently found in patients with NF1. Therefore, MRI should be obtained prior to planning spinal procedures in these patients; however, dural ectasia is not the cause of limb overgrowth. Lisch nodules are benign hamartomas of the iris. The lesions are uncommon during early childhood but are found in all adults with NF1. Juvenile xanthogranuloma has a low occurrence rate in patients with NF1; its presence is associated with juvenile chronic myeloid leukemia. Malignant peripheral nerve sheath tumors, formally called neurofibrosarcoma, result from malignant degeneration of a plexiform neurofibroma. This condition occurs in up to 4% of patients with NF1. Localized pain, an enlarging mass, or progressive neurologic symptoms suggest a malignant peripheral nerve sheath tumor in a patient with NF1. However, progressive neurologic symptoms also may occur with benign growth of a plexiform neurofibroma. Alman BA, Goldberg MJ: Syndromes of orthopaedic importance, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, pp 287-338.

Question 12

A 14-year-old girl with a right thoracic curve from T4 through L2 measuring 78 degrees is scheduled to undergo posterior spinal fusion for scoliosis. The surgical plan is to fuse from T3 through L2, using pedicle screws at L2 and about the apex at T8. What neural monitoring modality is most likely to identify a reversible neurologic deficit during surgery?

Explanation

Neural monitoring during scoliosis surgery was initially developed to avoid the devastating effects of spinal cord injury, particularly paraplegia. Monitoring in some form has become standard for this type of surgery. Somatosensory-evoked potentials in the lower extremities will detect many but not all neurologic difficulties with the spinal cord. Anterior spinal cord vascular disruption also can be detected by monitoring motor potentials. Electromyography following stimulation of lumbar pedicle screws can prevent nerve root injury that is the result of misplacement of the screws. This is best documented in the lumbar spine and has not been routinely used in the thoracic spine. The most common neural deficits following spinal surgery, however, are in the upper extremities because of the positioning of the patient in the prone position for long periods. In Schwartz and associates series of 500 patients, impending upper extremity neural injury was detected by somatosensory-evoked potentials in 18 (3.6%) patients. In contrast, lower extremity deficits were detected by combined motor- and sensory-evoked potentials in only 2 (0.4%) out of 500 patients in Padberg and associates series. Neural compression in the upper extremity can be easily detected by somatosensory-evoked potentials, and injury can be prevented by repositioning the patient. Padberg AM, Wilson-Holden TJ, Lenke LG, Bridwell KH: Somatosensory- and motor-evoked potential monitoring without wake-up test during idiopathic scoliosis surgery: An accepted standard of care. Spine 1998;23:1392-1400.

Question 13

Figure 46 shows the radiograph of an obese 12-year-old boy who has had left hip pain for the past 3 months. What is the best course of action?

Explanation

The patient has an obvious slipped capital femoral epiphysis of the left hip for which the recommended treatment is percutaneus pinning in situ. Development of a contralateral slip is less likely at this age; therefore, observation of the right hip is indicated because there is no general agreement regarding prophylactic fixation. Typically, there is no role for spica casting. Physical therapy is not indicated as a primary treatment, and reduction is contraindicated, as it has been associated with osteonecrosis. Loder RT, Aronsson DD, Greenfield ML: The epidemiology of bilateral slipped capital femoral epiphysis: A study of children in Michigan. J Bone Joint Surg Am 1993;75:1141-1147. Aronsson DD, Karol LA: Stable slipped capital femoral epiphysis: Evaluation and management. J Am Acad Orthop Surg 1996;4:173-181. Hurley JM, Betz RR, Loder RT, Davidson RS, Alburger PD, Steel HH: Slipped capital femoral epiphysis: The prevalence of late contralateral slip. J Bone Joint Surg Am 1996;78:226-230.

Question 14

A 7-year-old boy sustained a head contusion and small bowel injuries in a motor vehicle accident in which he was wearing a lap belt. He subsequently required a bowel resection. Six weeks after the accident, his parents note a painful mass in his lower back. His neurologic examination is normal. A radiograph and CT scans are shown in Figures 47a through 47c. Definitive management should now consist of

Explanation

The posttraumatic lumbar kyphotic deformity will not remodel and is likely to worsen with time because the central line of gravity lies anterior to the deformity and the ligamentous disruption will not heal. The worsening deformity also puts the patient at some risk for future neurologic damage. Ebraheim NA, Savolain ER, Southworth SR, et al: Pediatric lumbar seat belt injuries. Orthopedics 1991;14:1010-1013.

Question 15

A 5-month-old girl with arthrogryposis has a limb-length discrepancy. Examination and radiographs reveal unilateral hip dislocation. Management should consist of

Explanation

In this age group of patients with arthrogryposis, open reduction through a medial approach is generally recommended. Open reduction through an anterior approach is reserved for patients in which a medial approach has failed or for older patients who require simultaneous femoral shortening and/or pelvic osteotomy. Closed treatment of unilateral hip dislocation in association with arthrogryposis is rarely successful. In bilateral hip dislocation associated with arthrogrypsis, the consensus is that the hips are best left unreduced because of the difficulty in obtaining excellent clinical and radiographic results bilaterally. Staheli LT, Chew DE, Elliot JS, Mosca VS: Management of hip dislocations in children with arthrogryposis. J Pediatr Orthop 1987;7:681-685. Szoke G, Staheli LT, Jaffe K, Hall JG: Medial-approach open reduction of hip dislocation in amyoplasia-type arthrogryposis. J Pediatr Orthop 1996;16:127-130.

Question 16

A 10-year-old boy who has had progressive low back and right buttock pain for the past 3 days is now unable to bear weight on the right side secondary to pain. He has a temperature of 101.3 degrees F (38.5 degrees C). Examination reveals full hip range of motion; but he reports pain on the right side with external rotation. Pain is elicited with compression of the iliac wings and with direct palpation of the right sacroiliac (SI) joint. An MRI scan of the pelvis shows no abscess, but there is inflammation of the SI joint. Management should consist of

Explanation

The clinical presentation and MRI findings are consistent with an acute infection of the SI joint. Bed rest and nonsteroidal anti-inflammatory drugs alone are insufficient to treat the problem. Staphylococcus aureus is the causative organism in most of these infections; therefore, unless there is an unusual factor in the history such as IV drug use, immune system compromise, or unusual travel, SI joint aspiration is unnecessary. It is often difficult to enter the SI joint, even under radiographic guidance. Management should consist of hospital admission and IV antibiotics. Blood cultures may be positive and should be obtained prior to starting antibiotics. Surgical fusion of the SI joint is not indicated. Morrissey RT: Bone and Joint Sepsis in Pediatric Orthopaedics. Philadelphia, PA, JB Lippincott, 1990. Beaupre A, Carroll N: The three syndromes of iliac osteomyelitis in children. J Bone Joint Surg Am 1979;61:1087-1092.

Question 17

Figures 48a and 48b show the elbow radiographs of a 5-year-old boy who fell from a tree after dinner. Examination reveals that he is unable to extend his wrist. Management should consist of immediate

Explanation

In the absence of vascular compromise, there has been no proven value to proceeding immediately to surgery, especially when the patient has a full stomach and runs a significant risk of perioperative aspiration. It would be more prudent to wait until the next morning with a surgical plan of closed reduction and pinning. Open reduction should be reserved for the unusual case of where closed treatment has not been successful. The implication that there may be a radial nerve injury associated with this fracture does not alter the treatment plan, and with a high level of certainty would be expected to resolve. Attempting closed reduction in the emergency department creates the opportunity for uncertain results and is not tolerated well by most patients. Skeletal traction, with its associated lengthy hospitalization and the technical difficulties associated with both the traction and radiographic evaluations, has fallen into disfavor for typical clinical situations. Iyengar SR, Hoffinger SA, Townsend DR: Early versus delayed reduction and pinning of type III displaced supracondylar fractures of the humerus in children: A comparative study. J Orthop Trauma 1999;13:51-55.

Question 18

In addition to the radiographic features seen in Figures 49a and 49b, this patient will most likely have which of the following findings?

Explanation

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

Question 19

A biopsy of the involved physis in a patient with slipped capital femoral epiphysis (SCFE) would most likely reveal

Explanation

Vascular invasion, histologically similar to granulation tissue, has been noted between the columns in the zone of hypertrophy, leading to the theory of microtrauma as an etiology. SCFE is also associated with conditions that increase the height of the zone of hypertrophy, including the adolescent growth spurt and endocrinopathies. The perichondral ring has been shown to decrease in thickness with age. Normal undulations in the growth plate also decrease during this time, possibly further destabilizing the physis. Abnormal accumulations of proteoglycan have been reported. Chung SM, Batterman SC, Brighton CT: Shear strength of the human femoral capital epiphyseal plate. J Bone Joint Surg Am 1976;58:94-103.

Question 20

A 12-year-old girl has a 4-cm limb-length discrepancy following a fracture of the left distal femur 2 years ago. Examination reveals 18 degrees of genu valgum on the involved side, with 7 degrees of genu valgum on the opposite side. Radiographs show that the left distal femoral growth plate is now closed; however, the tibial growth plate is still open. Her bone age matches her chronologic age. Management should consist of

Explanation

The patient has a projected limb-length discrepancy of 7 cm. This includes the 4 cm she already has, plus 3 cm expected growth of the uninvolved distal femur during the 3 years of growth she has remaining. She also has moderate limb deformity. Femoral lengthening is considered the treatment of choice because it can address both the limb-length discrepancy and the deformity. Epiphyseodesis will not result in limb-length equality at maturity, with only approximately 1.8 cm of equalization expected from this procedure. Use of closed femoral shortening of 7 cm runs the risk of weakening the quadriceps on the normal side and will leave the patient with a remaining residual valgus deformity. Tibial lengthening will leave the knees at different levels. A shoe lift can be prescribed as a temporary measure but is not a good long-term solution. Westh RN, Menelaus MB: A simple calculation for the timing of epiphyseal arrest: A further report. J Bone Joint Surg Br 1981;63:117-119. Sasso RC, Urquhart BA, Cain TE: Closed femoral shortening. J Pediatr Orthop 1993;13:51-56.

Question 21

The parents of a previously healthy 3-year-old child report that she refused to walk on awakening. Examination later in the day reveals that the patient can walk but with a noticeable limp. She has a temperature of 99.5 degrees F (37.5 degrees C). Range of motion measurements are shown in Figure 50. An AP pelvis radiograph is normal. Laboratory studies show a WBC count of 9,000/mm3 and an erythrocyte sedimentation rate of 10 mm/h. Management should consist of

Explanation

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

Question 22

A 12-year-old boy with hemophilia A and no known inhibitors sustains a tibia fracture and has pain with passive motion of the deep toe flexors. Appropriate management should consist of

Explanation

In a patient with hemophilia, factor replacement followed by assessment of compartment pressures is essential. If the patient has inhibitors, the problem is more difficult. Porcine factor has been helpful in patients with inhibitory antibodies. Recent evidence points to using activated factor VII and bypassing the intrinsic pathway. Desmopressin is an adjunct to therapy but is not as effective as factor VII. Dumontier C, Sautet A, Man M, Bennani M, Apoil A: Entrapment and compartment syndromes of the upper limb in haemophilia. J Hand Surg Br 1994;19:427-429. Carr ME Jr, Loughran TP, Cardea JA, Smith WK, Kuhn JG, Dottore MV: Successful use of recombinant factor VIIa for hemostasis during total knee replacement in a severe hemophiliac with high-titer factor VIII inhibitor. Int J Hematol 2002;75:95-99.

Question 23

A 10-year-old boy with spastic diplegic cerebral palsy walks in a crouched position with the hips and knees flexed. Maximum knee flexion is 15 degrees during early swing phase. Instrumented gait analysis shows quadriceps activity from terminal stance throughout swing phase. Treatment should consist of

Explanation

The rectus femoris muscle spans two joints and is active during running, sprinting, and walking at a fast pace during the preswing and early swing phase of gait. In these situations, the muscle helps to generate power to initiate hip flexion while absorbing or controlling the rate of knee flexion during early swing phase. Quadriceps activity, including the rectus femoris, is not normally needed when walking at a routine cadence. However, rectus femoris activity is commonly noted during preswing and the swing phase in patients with cerebral palsy, particularly those with diplegia. In an effort to initiate swing phase, the rectus femoris is "overactive." As a result, the knee flexion that commonly occurs at terminal stance and initial swing is restricted. Instead of achieving the normal 50 to 60 degrees of flexion during early swing, this patient's knee flexion is limited to 15 degrees. The goal of treatment is to retain rectus femoris activity for initiation of hip flexion but to diminish its restraint on knee flexion. Studies have shown that transfer of the distal rectus femoris tendon provides more flexion of the knee during the swing phase of gait than simply releasing the tendon. V-Y lengthening of the quadriceps tendon or a Z lengthening of the patellar tendon causes too much weakening of the quadriceps muscle and worsens the crouch deformity. In addition to transfer of the rectus femoris tendon, other procedures are often done concomitantly to obtain the best balance and realignment of hip-knee-ankle activity. Aiona MD: Guidelines for managing lower extremity problems in cerebral palsy, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1534-1541. Chambers H, Laure A, Kaufman K, Cardelia M, Sutherland D: Prediction of outcome after rectus femoris surgery in cerebral palsy: The role of cocontraction of the rectus femoris and vastus lateralis. J Pediatr Orthop 1998;18:703-711.

Question 24

A 4-year-old boy with arthrogryposis has little active motion of his knees or elbows. Both elbows are in full extension with good triceps strength, but he is unable to bring his hand to his face or feed himself. Management should consist of

Explanation

Elbow release and triceps transfer to restore motion can be performed in children who are age 4 years and older. The ability to flex the elbow either actively or passively is of great assistance in activities of daily living. Van Heest A, Waters PM, Simmons BP: Surgical treatment of arthrogrypsosis of the elbow. J Hand Surg Am 1998;23:1063-1070.

Question 25

A 14-year-old competitive gymnast has had activity-related low back pain for the past month. Examination reveals no pain with forward flexion, but she has some discomfort when resuming an upright position. She also has pain with extension and lateral bending of the spine. The neurologic examination is normal. Popliteal angles measure 20 degrees. AP, lateral, and oblique views of the lumbar spine are negative. What is the next most appropriate step in management?

Explanation

Symptoms of activity-related low back pain, physical findings of pain with extension, lateral bending, and resuming an upright position, and relative hamstring tightness are consistent with spondylolysis. While the initial diagnostic work-up should include plain radiographs of the lumbosacral spine, the findings may be negative because it can take weeks or months for the characteristic changes to become apparent. SPECT has been a useful adjunct in the diagnosis of spondylolysis when plain radiographs are negative. Since the patient's pain is activity related and she is otherwise healthy, evaluation for infection is not indicated. Because the neurologic examination is normal, electromyography, nerve conduction velocity studies, and MRI are not indicated. CT can be used in those instances in which SPECT and bone scans are negative. Ciullo JV, Jackson DW: Pars interarticularis stress reaction, spondylolysis, and spondylolisthesis in gymnasts. Clin Sports Med 1985;4:95-110. Collier BD, Johnson RP, Carrera GF, et al: Painful spondylolysis or spondylolisthesis studied by radiography and single photon emission computed tomography. Radiology 1985;154:207-211. Jackson DW, Wiltse LL, Cirincione RT: Spondylolysis in the female gymnast. Clin Orthop 1976;117:68-73.

Question 26

A 13-year-old obese male presents with acute left hip pain and an inability to bear weight following a minor fall. He reports intermittent mild hip pain for 3 months prior. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant risk factor for developing avascular necrosis (AVN) in this patient?

Explanation

The inability to bear weight, with or without crutches, defines an unstable SCFE according to the Loder classification. Unstable slips carry a significantly higher risk of AVN (up to 47%) compared to stable slips.

Question 27

A 3-year-old girl is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra at T8. Neurological examination is normal. As part of her initial workup, which of the following screening modalities is mandatory?

Explanation

Congenital scoliosis is highly associated with VACTERL anomalies. Up to 30% of patients have genitourinary abnormalities and 10-15% have cardiac defects, making a renal ultrasound and echocardiogram mandatory during initial evaluation.

Question 28

A 6-year-old boy falls from monkey bars and sustains a significantly displaced, extension-type supracondylar humerus fracture. On examination, he is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury presents as an inability to form the "OK" sign due to weakness of the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 29

A 6-week-old female infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the parents report she has stopped actively kicking her left leg. Examination reveals decreased active knee extension on the left side. What is the most appropriate next step in management?

Explanation

The infant has developed a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness should be discontinued temporarily until active quadriceps function returns, followed by a reassessment of treatment options.

Question 30

A 13-year-old girl twists her ankle while playing soccer. Radiographs reveal a fracture of the anterolateral aspect of the distal tibial epiphysis. What is the primary deforming force and mechanism responsible for this specific injury pattern?

Explanation

The patient has a juvenile Tillaux fracture, which occurs when the anterior inferior tibiofibular ligament (AITFL) avulses the anterolateral distal tibial epiphysis. This injury occurs via an external rotation mechanism during the transitional period of asymmetric distal tibial physeal closure.

Question 31

A 4-year-old boy presents with a 2-day history of right hip pain and refusing to bear weight. His temperature is 38.8 Celsius (101.8 F). Laboratory studies show a WBC count of 13,000/mm3, ESR of 45 mm/hr, and CRP of 3.0 mg/dL. Radiographs of the hip are normal. Based on these findings, what is the most appropriate next step?

Explanation

This patient meets all four Kocher criteria for septic arthritis (non-weight-bearing, temp >38.5 C, ESR >40, WBC >12,000), giving a 99% probability of the diagnosis. Urgent hip aspiration is required for definitive diagnosis and to guide treatment before considering surgical irrigation.

Question 32

A 5-year-old boy sustains a closed, isolated midshaft femur fracture. He weighs 22 kg (48 lbs). According to the AAOS Clinical Practice Guidelines, which of the following is the most appropriate definitive treatment?

Explanation

For children aged 5-11 years with isolated femur fractures who weigh less than 50 kg, flexible intramedullary nailing is the treatment of choice. It offers excellent alignment, faster recovery, and avoids the risk of avascular necrosis associated with rigid piriformis-entry nails in this age group.

Question 33

A 12-year-old boy presents with right hip pain and inability to bear weight for the past 24 hours. Radiographs confirm a slipped capital femoral epiphysis (SCFE).

According to the Loder classification, which of the following is the most likely major complication associated with his condition?

Explanation

The inability to bear weight with or without crutches defines an unstable SCFE according to the Loder classification. Unstable slips carry a high risk of avascular necrosis (AVN), ranging from 20% to 50%, compared to nearly 0% in stable slips.

Question 34

A 3-month-old girl with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, her parents report that she is no longer actively extending her knee on the treated side. Which of the following positioning errors is the most likely cause of this complication?

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy and decreased active knee extension. Hyperabduction increases the risk of avascular necrosis (AVN) of the femoral head.

Question 35

A 4-year-old boy is brought to the emergency department after a high-speed motor vehicle collision. Lateral cervical spine radiographs reveal a 3.5 mm anterior displacement of C2 on C3. Swischuk's line (posterior cervical line) passes 1 mm anterior to the anterior aspect of the posterior arch of C3. What is the most appropriate management?

Explanation

The findings describe physiologic pseudosubluxation of C2 on C3, common in children under 8 years old. A Swischuk line passing within 1.5 mm of the anterior aspect of the C3 posterior arch confirms this is a benign, physiologic variant requiring no intervention.

Question 36

A 14-year-old female presents with a progressive right thoracic scoliotic curve. Radiographs reveal an adolescent idiopathic scoliosis (AIS) curve measuring 55 degrees. Her Risser stage is 0. What is the primary indication for surgical intervention in this patient?

Explanation

In Adolescent Idiopathic Scoliosis, surgical fusion is generally indicated for curves greater than 45-50 degrees, especially in patients with significant remaining growth (Risser 0). This prevents further progression, which inevitably occurs even after skeletal maturity for curves >50 degrees.

Question 37

A 6-year-old boy presents with an established nonunion of a lateral humeral condyle fracture sustained 2 years ago.

He demonstrates a progressive cubitus valgus deformity. Which of the following neurologic complications is most strongly associated with this condition?

Explanation

Nonunion of a lateral condyle fracture typically leads to a progressive cubitus valgus deformity. Over time, this valgus angulation stretches the ulnar nerve, leading to tardy (late) ulnar nerve palsy.

Question 38

A 2-year-old boy is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra at T8. Which of the following sets of screening studies is mandatory for this patient?

Explanation

Congenital scoliosis is frequently associated with VACTERL anomalies, necessitating evaluation of the genitourinary and cardiovascular systems. Up to 30% of these patients have structural urologic abnormalities (requiring renal ultrasound) and 10% have congenital heart defects (requiring an echocardiogram).

Question 39

A 9-year-old boy is diagnosed with Legg-Calvé-Perthes disease.

Anteroposterior pelvis radiographs reveal that the lateral pillar of the femoral head has collapsed to less than 50% of its original height. According to the Herring Lateral Pillar Classification, into which group does he fall, and what is the general prognosis?

Explanation

Maintaining <50% of the lateral pillar height defines Herring Group C. Children over the age of 8 with Group C involvement have a generally poor prognosis regarding joint congruency and early osteoarthritis, regardless of whether surgical containment is performed.

Question 40

A 5-year-old girl sustains a Gartland type III supracondylar humerus fracture.

Upon evaluation in the emergency department, her hand is pink and warm, but the radial pulse is absent. What is the most appropriate next step in management?

Explanation

A "pulseless, pink" hand following a supracondylar humerus fracture indicates adequate collateral perfusion. The standard of care is urgent closed reduction and percutaneous pinning (CRPP), which frequently restores the anatomic alignment and the radial pulse.

Question 41

A 3-year-old boy presents with a temperature of 38.8°C, an ESR of 45 mm/hr, a WBC count of 14,000/mm³, and refusal to bear weight on his left leg. According to the Kocher criteria, what is the approximate probability that this child has septic arthritis of the hip?

Explanation

The patient meets all 4 of the classic Kocher criteria (fever >38.5°C, ESR >40, WBC >12,000, and non-weight-bearing). The presence of all 4 criteria correlates with a 99% predictive probability for septic arthritis of the hip.

Question 42

A 4-year-old boy sustains an isolated closed diaphyseal fracture of the right femur. He is treated with an early spica cast. What is the maximum acceptable amount of initial fracture shortening in this age group to account for expected overgrowth?

Explanation

In children aged 2 to 10 years, femoral fractures stimulate a hyperemic response that leads to bony overgrowth. Approximately 1.5 to 2.0 cm (15-20 mm) of initial shortening is acceptable and expected to correct through this overgrowth phenomenon.

Question 43

A 5-year-old girl presents with a painless waddling gait. Radiographs reveal developmental coxa vara. The Hilgenreiner Epiphyseal Angle (HEA) is measured at 65 degrees. What is the most appropriate management?

Explanation

An HEA greater than 60 degrees in congenital coxa vara indicates a high risk of progression and nonunion of the cartilaginous defect. The definitive treatment is a valgus-producing proximal femoral osteotomy to convert shear forces into compressive forces.

Question 44

A 13-year-old girl sustains an inversion and external rotation injury to her ankle. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. Avulsion of which ligament is responsible for this specific fracture pattern?

Explanation

This is a Tillaux fracture, caused by external rotation forces. The anterior inferior tibiofibular ligament (AITFL) is stronger than the anterolateral distal tibial physis in adolescents, resulting in an avulsion fracture as the central and medial physis has already closed.

Question 45

A 6-month-old infant is noted to have a left-sided thoracic scoliosis measuring 25 degrees. The Rib-Vertebral Angle Difference (RVAD) of Mehta is measured at 28 degrees. What does this finding indicate regarding the natural history of the curve?

Explanation

In infantile idiopathic scoliosis, an RVAD (Mehta's angle) greater than 20 degrees is highly predictive of curve progression. These progressive curves typically require intervention, such as serial Mehta casting or bracing, to prevent severe deformity.

Question 46

A 14-year-old boy with Duchenne Muscular Dystrophy (DMD) has a progressive neuromuscular scoliosis of 40 degrees. His Forced Vital Capacity (FVC) is 45% of predicted. What is the recommended surgical strategy to optimize his quality of life and sitting balance?

Explanation

In DMD, scoliosis progresses rapidly and impairs sitting balance and respiratory function. Fusion extending to the pelvis is recommended for curves >20-30 degrees while the FVC is still >35% to level the pelvis, maintain sitting balance, and minimize perioperative pulmonary morbidity.

Question 47

A 4-month-old infant presents to the emergency department with a swollen left thigh. Radiographs reveal a metaphyseal "corner" fracture of the distal femur. Which of the following steps is the most critical next action?

Explanation

Metaphyseal corner (or bucket-handle) fractures in non-ambulatory infants are highly specific for non-accidental trauma (child abuse). The immediate, mandatory next steps include ensuring the child's safety, performing a skeletal survey, and notifying CPS.

Question 48

A 9-year-old girl, whose weight is in the 40th percentile, presents with right groin pain and a limp. Radiographs confirm a slipped capital femoral epiphysis (SCFE).

Given her presentation, an endocrine workup is indicated. Which of the following is the most common underlying endocrine disorder associated with this condition?

Explanation

Atypical SCFE (patients aged <10 or >16, or weight < 50th percentile) warrants an endocrine workup. Hypothyroidism is the most common underlying endocrine disorder associated with atypical SCFE.

Question 49

A 5-year-old boy sustains a type III extension supracondylar humerus fracture. After closed reduction and percutaneous pinning, the hand is noted to be pink but lacks a palpable radial pulse. Doppler confirms a monophasic signal at the wrist. What is the most appropriate next step in management?

Explanation

A pink, pulseless hand following adequate closed reduction and pinning of a supracondylar humerus fracture indicates sufficient collateral circulation. Observation is the recommended management, as pulses typically return over several days.

Question 50

A 2-year-old boy is diagnosed with a congenital hemivertebra in the lower thoracic spine. Which of the following screening studies is most critically indicated in the initial workup?

Explanation

Congenital scoliosis is frequently associated with VACTERL anomalies, notably genitourinary and intraspinal defects. A renal ultrasound and a whole-spine MRI are indicated to screen for missing kidneys, structural urinary tract defects, and a tethered cord.

Question 51

A 3-month-old girl with developmental dysplasia of the hip (DDH) is being treated in a Pavlik harness. During a follow-up examination, the orthopedist notes decreased active extension of the left knee. What is the most likely cause of this finding?

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy. This presents as decreased active knee extension and usually resolves with temporary relaxation of the anterior straps.

Question 52

A 14-year-old boy sustains a juvenile Tillaux fracture of the distal tibia while skateboarding.

This fracture pattern occurs due to the specific sequence of distal tibial physeal closure. What mechanism of injury is most classically responsible for this fracture?

Explanation

A juvenile Tillaux fracture is a Salter-Harris III avulsion of the anterolateral distal tibial epiphysis caused by an external rotation force on the foot. It occurs because the lateral portion of the distal tibial physis is the last to close.

Question 53

A 6-year-old child falls from monkey bars and sustains a displaced extension-type supracondylar humerus fracture. Which of the following physical examination findings corresponds to the most common neurological injury associated with this specific fracture pattern?

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury results in the inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (an abnormal "A-OK" sign).

Question 54

Which of the following fixed spinopelvic radiographic parameters is most strongly associated with the severity and progression risk of an isthmic spondylolisthesis in a pediatric patient?

Explanation

High pelvic incidence strongly correlates with the severity and progression risk of isthmic spondylolisthesis. It is a fixed morphological parameter defined as the sum of pelvic tilt and sacral slope.

Question 55

A 13-year-old boy underwent in situ pinning for a stable slipped capital femoral epiphysis (SCFE) 6 months ago. He now presents with a severely stiff, painful hip. Radiographs show a concentric, severe narrowing of the joint space. What is the most likely diagnosis?

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute loss of articular cartilage and a globally stiff, painful hip. It is strongly associated with unrecognized intra-articular hardware penetration.

Question 56

A 6-year-old child sustains a displaced lateral condyle fracture of the humerus that is missed and not treated operatively. If this progresses to a nonunion, which of the following long-term complications is most likely to develop years later?

Explanation

Nonunion of a lateral condyle humerus fracture leads to progressive cubitus valgus deformity. This chronic valgus stretching of the ulnar nerve over time frequently results in a tardy ulnar nerve palsy.

Question 57

A 5-year-old boy presents with a limp, a temperature of 38.9°C (102°F), and an inability to bear weight on his right leg. Laboratory tests show an ESR of 55 mm/hr and a WBC count of 14,000/mm3. According to the modified Kocher criteria, what is the predictive probability that this child has septic arthritis of the hip?

Explanation

The modified Kocher criteria include fever >38.5°C, inability to bear weight, ESR >40 mm/hr, and WBC >12,000/mm3. The presence of all four criteria yields a 99% probability of septic arthritis.

Question 58

An 8-month-old infant is evaluated for a left-sided thoracic spinal curve. Radiographs show an infantile idiopathic scoliosis with a Rib-Vertebra Angle Difference (RVAD) of 28 degrees. What is the most appropriate next step in management?

Explanation

Infantile idiopathic scoliosis with a Rib-Vertebra Angle Difference (RVAD) > 20 degrees (Phase 2) indicates a highly progressive curve. Serial derotational casting (Mehta cast) is the standard of care to guide spinal growth and prevent progression.

Question 59

An 11-year-old boy weighing 65 kg (143 lbs) sustains a closed, length-stable midshaft femur fracture. If this fracture is treated with titanium elastic nails (TENs), the patient is at highest risk for which of the following complications compared to submuscular plating?

Explanation

Titanium elastic nails are ideal for pediatric femur fractures in children aged 5-11 weighing under 50 kg (110 lbs). Patients heavier than 50 kg have significantly higher rates of malunion and loss of sagittal alignment when treated with flexible nails.

Question 60

A 12-year-old premenarchal girl presents with adolescent idiopathic scoliosis. Radiographs demonstrate a right thoracic curve of 32 degrees. Her Risser stage is 0. What is the most appropriate management?

Explanation

Bracing in adolescent idiopathic scoliosis is indicated for curves between 25 and 40 degrees in skeletally immature patients (Risser 0-2). The goal of the TLSO brace is to halt progression, not to correct the existing deformity.

Question 61

A 7-year-old boy with Down syndrome undergoes routine cervical spine screening radiographs. Flexion-extension views reveal an Atlanto-Dens Interval (ADI) of 9 mm. He is neurologically intact and asymptomatic. What is the recommended management?

Explanation

Atlantoaxial instability is common in Down syndrome. An ADI > 4.5 mm suggests instability, and an ADI > 8-10 mm or the presence of neurologic symptoms is an absolute indication for posterior C1-C2 arthrodesis.

Question 62

A 13-year-old obese boy presents with 3 weeks of left knee pain and a limp. Examination reveals obligatory external rotation of the left hip when it is passively flexed. Radiographs confirm a mild slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate initial management?

Explanation

The standard of care for a stable, mild SCFE is in situ pinning with a single central cannulated screw. Multiple screws increase the risk of joint penetration and avascular necrosis without providing significant biomechanical advantage.

Question 63

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. On initial presentation, his hand is pink but the radial pulse is absent. Following closed reduction and percutaneous pinning, the hand remains pink and well-perfused, but the radial pulse is still non-palpable. What is the most appropriate next step in management?

Explanation

A pink, pulseless hand following adequate reduction of a supracondylar humerus fracture should be managed with close clinical observation. Vascular exploration is indicated only if the hand is persistently cold, pale, and poorly perfused after reduction.

Question 64

A 14-year-old female gymnast presents with persistent low back pain that radiates to her posterior thighs. Nonoperative management has failed after 6 months. Radiographs demonstrate a Grade III isthmic spondylolisthesis at L5-S1 with a slip angle of 45 degrees. Which of the following surgical treatments is most appropriate?

Explanation

High-grade (Grade III or IV) isthmic spondylolisthesis failing conservative management in adolescents is best treated with L5-S1 posterior or global spinal fusion. Pars repair is reserved for Grade I slips or spondylolysis without significant slippage.

Question 65

A 7-year-old boy presents with a painless limp of 2 months duration. Radiographs reveal fragmentation and increased density of the right capital femoral epiphysis consistent with Legg-Calve-Perthes disease. Which of the following is the most significant prognostic factor for the final outcome of his hip?

Explanation

Age at clinical presentation is the most critical prognostic factor in Legg-Calve-Perthes disease. Children who present at an older age (typically >8 years) have a higher risk of a poor radiographic and clinical outcome compared to younger children.

Question 66

A 2-month-old girl is being treated with a Pavlik harness for developmental dysplasia of the hip. At her 2-week follow-up, the mother reports that the infant has stopped kicking her left leg. On examination, the left knee does not actively extend, but passive range of motion is normal. Which of the following is the most appropriate management?

Explanation

Transient femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion. The appropriate management is to temporarily discontinue or loosen the harness until active quadriceps function returns.

Question 67

A 6-month-old infant is referred for a left thoracic curve measuring 25 degrees. The rib-vertebra angle difference (RVAD) of Mehta at the apical vertebra is 25 degrees. There are no other abnormalities. What is the most likely natural history of this curve?

Explanation

In infantile idiopathic scoliosis, an RVAD (Mehta's angle) greater than 20 degrees strongly indicates a high likelihood of curve progression. Curves with an RVAD less than 20 degrees typically resolve spontaneously.

Question 68

A 6-year-old boy weighing 22 kg (48 lbs) sustains a closed, isolated midshaft femur fracture after falling from a tree. What is the most appropriate treatment?

Explanation

Flexible intramedullary nailing is the treatment of choice for midshaft femur fractures in school-aged children (typically 5-11 years old) weighing less than 50 kg. Immediate spica casting is preferred for children under 5 years, while rigid nailing is reserved for older adolescents.

Question 69

A 13-year-old boy sustains an ankle injury. Radiographs and CT scan demonstrate a fracture of the distal tibia with a sagittal fracture through the epiphysis, an axial fracture through the physis, and a coronal fracture through the posterior metaphysis. This injury is best classified as an equivalent to which Salter-Harris pattern?

Explanation

A triplane fracture involves the epiphysis, physis, and metaphysis of the distal tibia. Because the fracture line traverses all three zones, it acts biomechanically and anatomically as a Salter-Harris Type IV equivalent.

Question 70

A 14-year-old girl sustains a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the primary mechanism of injury for this specific fracture pattern?

Explanation

A juvenile fracture of Tillaux is an avulsion of the anterolateral distal tibial epiphysis caused by tension from the anterior inferior tibiofibular ligament (AITFL). This typically occurs due to external rotation of the foot within the mortise as the physis begins its asymmetric medial-to-lateral closure.

Question 71

A 14-year-old girl underwent uncomplicated in situ pinning for a stable SCFE 6 months ago. She now presents with a worsening limp and a stiff hip. Examination reveals a painful, global restriction of hip motion. Radiographs show concentric narrowing of the hip joint space. What is the most likely diagnosis?

Explanation

Chondrolysis is a recognized complication of SCFE characterized by acute cartilage necrosis, presenting with severe stiffness, global loss of motion, and concentric joint space narrowing on radiographs. It can occur spontaneously or secondary to hardware penetration.

Question 72

A newborn male is noted to have congenital scoliosis due to a fully segmented hemivertebra at T8.

Which of the following screening evaluations is mandatory to detect associated, occult abnormalities?

Explanation

Congenital scoliosis has a high association with VACTERL anomalies, notably cardiac (approx 20%) and genitourinary/renal anomalies (approx 30%). An echocardiogram and renal ultrasound are essential screening tools in these patients.

Question 73

A 4-week-old infant is referred for congenital muscular torticollis. The head is tilted to the right and rotated to the left. A firm mass is palpable in the right sternocleidomastoid muscle. In addition to physical therapy for the neck, what additional screening is most strongly indicated?

Explanation

Congenital muscular torticollis has a known association with developmental dysplasia of the hip (DDH), occurring in up to 10-20% of cases. Screening with a hip ultrasound is strongly recommended for these infants.

Question 74

A 5-year-old boy sustains a fall and presents with elbow pain. Radiographs reveal a displaced (>2 mm) lateral condyle fracture of the humerus. If left untreated, what is the most likely long-term complication of this injury?

Explanation

Displaced pediatric lateral condyle fractures have a high rate of nonunion if not surgically stabilized. A nonunion can lead to a progressive cubitus valgus deformity, which stretches the ulnar nerve and often results in tardy ulnar nerve palsy.

Question 75

A 10-year-old boy is evaluated for a leg length discrepancy 2 years after sustaining a distal femoral physeal fracture. Radiographs show a central 30% bony bar across the distal femoral physis with 2 years of growth remaining. What is the most appropriate management?

Explanation

For a physeal bar occupying less than 50% of the physis in a child with at least 2 years of remaining growth, resection of the bar with interposition of fat or Cranioplast is the recommended treatment to restore longitudinal growth.

Question 76

A 7-year-old girl with spastic quadriplegic cerebral palsy presents for routine evaluation. Pelvic radiographs demonstrate a Reimers migration percentage of 55% in the right hip. There is no evidence of joint space narrowing or femoral head deformity. What is the most appropriate surgical management?

Explanation

In a child with spastic cerebral palsy and hip subluxation with a migration percentage >50%, soft tissue release alone is insufficient. Bony reconstruction with a varus derotational osteotomy (VDRO) and a concurrent pelvic osteotomy is required to provide stable, long-term coverage.

Question 77

A 12-year-old obese boy presents with acute-on-chronic left hip pain and inability to bear weight. Radiographs confirm an unstable slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate initial management to minimize the risk of avascular necrosis?

Explanation

Unstable SCFE is associated with a high rate of avascular necrosis. Urgent capsulotomy and in situ pinning or gentle reduction are recommended to decompress the joint and stabilize the epiphysis.

Question 78

A 3-month-old girl is being treated for developmental dysplasia of the hip with a Pavlik harness. During a follow-up visit, the mother notes that the child is no longer kicking her left leg. Examination reveals absent active knee extension on the left. The most appropriate next step is to:

Explanation

Absent active knee extension indicates a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness should be discontinued immediately to allow the nerve to recover.

Question 79

A 6-year-old boy presents with a limp and hip pain. Radiographs demonstrate Legg-Calve-Perthes disease with >50% lateral pillar collapse (Herring Group C). According to the literature, which of the following best describes the expected outcome?

Explanation

According to the Herring lateral pillar classification, patients over 8 years with Group B/C have better outcomes with surgery. However, Group C hips (regardless of age) generally have poor outcomes, and surgical containment does not significantly alter the natural history.

Question 80

A 5-year-old boy sustains a completely displaced extension-type supracondylar fracture of the humerus. On examination, the hand is pink and warm, but the radial pulse is absent. After urgent closed reduction and percutaneous pinning, the hand remains pink and warm, but the radial pulse remains non-palpable. What is the most appropriate next step?

Explanation

In a pulseless, pink, and well-perfused hand following a completely displaced supracondylar fracture, observation is the standard of care if perfusion remains intact after reduction and pinning. Vascular exploration is reserved for a pulseless, white (ischemic) hand.

Question 81

A 14-year-old boy sustains a Salter-Harris III fracture of the anterolateral distal tibial epiphysis (Tillaux fracture). This fracture pattern is directly caused by avulsion from which of the following structures?

Explanation

A juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis. It is caused by tension from the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury.

Question 82

A newborn is diagnosed with a congenital hemivertebra in the thoracic spine. Which of the following is the most appropriate initial screening protocol for associated anomalies?

Explanation

Congenital scoliosis is frequently associated with VACTERL anomalies. A renal ultrasound and echocardiogram are essential initial screening studies to rule out genitourinary and cardiac anomalies.

Question 83

A 13-year-old premenarchal girl presents with adolescent idiopathic scoliosis. Radiographs demonstrate a right thoracic curve of 55 degrees and a Risser stage of 0. Which of the following is the most appropriate treatment?

Explanation

A curve of 55 degrees in a skeletally immature patient (Risser 0, premenarchal) has a very high risk of progression. Posterior spinal fusion with instrumentation is the standard treatment for curves >50 degrees.

Question 84

A 6-year-old boy falls onto his outstretched arm and sustains a lateral condyle fracture of the humerus. Radiographs show a displacement of 4 mm. Which of the following is the most appropriate management?

Explanation

Lateral condyle fractures displaced >2 mm have a high risk of nonunion and subsequent cubitus valgus due to the pull of the extensor origin. Open reduction and internal fixation is the standard of care for >2 mm displacement.

Question 85

A 14-year-old male gymnast presents with chronic low back pain and a waddling gait. Radiographs reveal a Grade III isthmic spondylolisthesis at L5-S1 with a slip angle of 55 degrees. Nonoperative management has failed. What is the most appropriate surgical intervention?

Explanation

High-grade (Grade III or IV) isthmic spondylolisthesis in an adolescent requires stabilization. An in situ L4-S1 posterior instrumented fusion is the most reliable treatment to halt progression and relieve symptoms.

Question 86

A 7-month-old infant is brought to the emergency department with a swollen right thigh. Radiographs reveal a spiral fracture of the femoral shaft. The parents state the child caught his leg in the crib rails. What is the most critical next step in management?

Explanation

A spiral femur fracture in a non-ambulatory infant is highly suspicious for non-accidental trauma (child abuse). The most critical next step is a skeletal survey and involvement of child protective services.

Question 87

A 4-year-old boy presents with a 2-day history of right hip pain, a temperature of 38.8°C, and refusal to bear weight. Laboratory tests show an ESR of 50 mm/hr and a WBC of 14,000/mm³. Radiographs are unremarkable. What is the most appropriate next step?

Explanation

The patient meets 4 of 4 Kocher criteria for septic arthritis (fever, non-weight bearing, ESR >40, WBC >12,000). Ultrasound-guided aspiration is required to confirm the diagnosis and decompress the joint.

Question 88

A 6-year-old boy sustains a Bado Type I Monteggia fracture-dislocation. If a neurologic deficit is present upon initial examination, which of the following nerve branches is most likely affected?

Explanation

A Bado Type I Monteggia lesion involves an anterior dislocation of the radial head. The posterior interosseous nerve (PIN) is at the highest risk of injury due to its proximity to the radial neck.

Question 89

A 10-month-old infant presents with a left-sided thoracic curve measuring 30 degrees. The diagnosis of infantile idiopathic scoliosis is suspected. Which of the following radiographic parameters is most predictive of whether this curve will progress or spontaneously resolve?

Explanation

In infantile idiopathic scoliosis, Mehta's rib-vertebral angle difference (RVAD) is the most critical prognostic factor. An RVAD greater than 20 degrees is highly predictive of curve progression, whereas an RVAD less than 20 degrees typically indicates a resolving curve.

Question 90

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the left hip. The parents report that the child has stopped kicking the left leg. On examination, the left knee remains actively flexed, but the infant does not actively extend it. Patellar reflex is absent on the left. What is the most appropriate next step in management?

Explanation

The scenario describes a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness that manifests as an inability to extend the knee. The appropriate management is to temporarily remove the harness or adjust the anterior straps to decrease the degree of hip flexion, allowing the nerve to recover.

Question 91

A 6-year-old boy falls from the monkey bars and sustains a significantly displaced extension-type supracondylar humerus fracture. Prior to reduction, the examiner notes that the child cannot flex the interphalangeal joint of the thumb or the distal interphalangeal joint of the index finger. Which of the following nerves is most likely injured?

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type pediatric supracondylar humerus fractures. Injury clinically presents with the inability to flex the IP joint of the thumb and DIP joint of the index finger, disrupting the normal "OK" sign.

Question 92

A 13-year-old obese boy presents to the emergency department with sudden, severe left hip pain after tripping on a step. He is entirely unable to bear weight on the left leg, even with the use of crutches. Radiographs demonstrate a displaced slipped capital femoral epiphysis (SCFE). Which of the following represents the most significant complication risk specific to this presentation compared to a patient who can bear weight?

Explanation

The inability to bear weight even with assistive devices clinically defines an unstable SCFE. Unstable SCFE carries a significantly higher risk of osteonecrosis (up to 47%) compared to stable SCFE, necessitating careful surgical management and often joint decompression.

AAOS Orthopedic MCQs (Set 1): Spine Disorders, Sports Medicine & Arthroplasty | 2026 Board Review

Pediatric Orthopedic MCQs (Set 4): Hip, Spine & Trauma | ABOS OITE 2004 Review

Key Takeaway

Pediatric Orthopedic MCQs (Set 4): Hip, Spine & Trauma | ABOS OITE 2004 Review

Chapter Index