Orthopedic Pediatrics 2026 MCQs: Board Review Qs

Question 1

Figures 11a and 11b show the clinical photograph and radiograph of a newborn. Based on these findings, what is the best course of action?

Explanation

11b The newborn has posteromedial bowing of the tibia and calcaneal valgus deformity of the foot. Both are thought to be caused by abnormal intrauterine positioning. The foot deformity typically responds to stretching. The tibial bowing straightens with growth. The long-term problem is limb-length discrepancy. Heyman CH, Herndon CH, Heiple KG: Congenital posterior angulation of the tibia with talipes calcaneus. J Bone Joint Surg Am 1959;41:476-488.

Question 2

Figure 12 shows the radiograph of a patient who has anterior knee pain. History reveals a femoral fracture at age 5 years. What is the most likely cause of the deformity?

Explanation

The radiograph shows a recurvatum deformity of the proximal tibia with growth arrest of the tibial tubercle apophysis. This deformity has been described in association with femoral shaft fractures in children and has been attributed to a clinically silent, concommitant injury to the proximal tibial physes and also to iatrogenic injury associated with a proximal tibial traction pin. Overlengthened hamstrings and rupture of the posterior cruciate ligament may lead to knee hyperextension; however, these problems should not cause bone deformity. Osgood-Schlatter disease occurs when growth is nearly complete and usually leads to prominence of the tibial tubercle. Patellar tendon rupture is rare in children and would not cause this deformity unless the repair was performed with screws across the apophysis. Hresko MT, Kasser JR: Physeal arrest about the knee associated with non-physeal injuries of the lower extremity. J Bone Joint Surg Am 1989;71:698-703.

Question 3

An 11-year-old boy has had a fever and pain and swelling over the lateral aspect of his right ankle for the past 3 days. Examination reveals warmth, swelling, and tenderness over the lateral malleolus, and he has a temperature of 103.2 degrees F (39.5 degrees C). Laboratory studies show a WBC count of 13,200/mm3 with 61% neutrophils, an erythocyte sedimentation rate of 112 mm/h, and a C-reactive protein of 15.7. Radiographs and a T2-weighted MRI scan are shown in Figures 13a through 13c. Aspiration yields 1 mL of purulent fluid. Management should now consist of

Explanation

13b 13c The initial signs and symptoms of acute hematogenous osteomyelitis vary widely but usually include fever, bone pain, and impaired use of the involved extremity. In lower extremity infections, the child may limp or refuse to walk. Examination often reveals bone tenderness. In more advanced cases, erythema, warmth, and swelling may be present. The WBC and neutrophil counts are not always elevated, but the erythocyte sedimentation rate will be abnormal in more than 90% of patients. When the infection is diagnosed early, before a subperiosteal abscess has formed, antibiotics alone may be adequate to treat the infection. This patient has a more advanced infection, however, with the MRI scan revealing a subperiosteal abscess that was confirmed by aspiration. When an abscess is present, surgical drainage is generally indicated to remove devitalized tissue and to enhance the efficacy of the antibiotics. Further studies, such as bone or indium scans, are not necessary and will delay definitive treatment. Scott RJ, Christofersen MR, Robertson WW Jr, et al: Acute osteomyelitis in children: A review of 116 cases. J Pediatr Orthop 1990;10:649-652.

Question 4

Figure 14 shows the clinical photographs and radiograph of an 8-year-old girl who has a progressive equinus deformity of the right ankle. There is no history of trauma or infection. What is the most likely diagnosis?

Explanation

14 14 Focal scleroderma is characterized by the formation of patches of sclerotic skin, also known as morphea, or streaks of sclerosis (linear scleroderma). Systemic involvement in focal scleroderma is unusual; however, progression during childhood is common. Contracture of underlying tissues is common, often resulting in serious joint contractures. Bony changes similar to those seen in melorheostosis can be seen. This patient has characteristic skin changes, atrophy of the soft tissues, Achilles tendon contractures, and calcaneal deformities. There are no signs of arthrogryposis, which usually presents with bilateral congenital deformities, including equinovarus. Klippel-Trenaunay-Weber syndrome is characterized by venous malformation in association with focal overgrowth.

Question 5

Which of the following patients is considered the most appropriate candidate for an isolated split posterior tendon transfer?

Explanation

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.

Question 6

The mother of a 2-year-old boy reports that he had pain in the right hip all night and refuses to walk on the leg this morning. He is afebrile. Examination reveals pain on hip extension and adduction, but he is able to internally and externally rotate the hip approximately 20 degrees in each direction without pain. Laboratory studies reveal a WBC count of 7,400/mm3, with 62% polymorphonuclear neutrophil leukocytes. The AP radiograph shown in Figure 15 reveals a left teardrop distance of 8 mm, while the right side measures 10 mm. Which of the following diagnostic studies will best help confirm the diagnosis?

Explanation

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

Question 7

A senior resident is scheduled to perform a posterior medial release on a 10-month-old infant who has a congenital clubfoot deformity. Informed consent is obtained for the procedure. The supervising surgeon is obligated to give the parents what information?

Explanation

Informed consent is generally considered to be a process of mutual decision making between the physician and patient. The physician is required to provide to the patient all material information that is needed for the patient to make an informed decision. The courts have held that a patient's choice of surgeon is as important to the consent as the procedure itself. Assistance by a surgical trainee with adequate supervision is permissible when there has been adequate disclosure. Adequate supervision may be defined as active participation by the attending during the essential parts of the procedure. Allowing a substitute surgeon to operate on a patient without the patient's knowledge "ghost surgery" may result in charges of battery against the substitute surgeon and malpractice against the surgeon to whom the patient gave consent. Kocher MS: Ghost surgery: The ethical and legal implications of who does the operation. J Bone Joint Surg Am 2002;84:148-150.

Question 8

Figure 16 shows the clinical photograph of a 3-month-old infant with a foot deformity that has been nonprogressive since birth. Examination reveals that the deformity corrects actively and with passive manipulation. There is no associated equinus. Management should consist of

Explanation

The patient has bilateral metatarsus adductus deformities. In a long-term follow-up study by Farsetti and associates, deformities that were passively correctable spontaneously resolved and no treatment was required. More rigid deformities were successfully treated with serial manipulation, with good results in 90%. There were no poor results. Therefore, observation is the management of choice for passively correctable deformities. In feet that are more rigid, serial manipulation and casting is the management of choice.

Question 9

Figure 17 shows the radiograph of an 11-year-old boy with Duchenne muscular dystrophy who has been nonambulatory for the past 2 years. Management of the spinal deformity should consist of

Explanation

The presence of any curve greater than 20 degrees in a nonambulatory patient with Duchenne muscular dystrophy is an indication for posterior fusion with instrumentation. Because of progressive cardiomyopathy and pulmonary deficiency, waiting until the curve is larger can increase the risk of pulmonary or cardiac complications during or following surgery. There is some disagreement as to whether all such fusions must extend to the pelvis. Bracing or other nonsurgical management is ineffective and is not indicated in this situation. Sussman M: Duchenne muscular dystrophy. J Am Acad Orthop Surg 2002;10:138-151.

Question 10

A 13-year-old girl with Down syndrome has bilateral chronic patellar dislocations. She denies knee pain. She is able to straighten her knees and walks with a symmetric but awkward gait. She does not flex her knees in midstance. Examination reveals that the patellae cannot be brought into a reduced position. Management should consist of

Explanation

Chronic dislocation of the patella is occasionally seen in patients with Down syndrome. In early childhood, patellar realignment may restore stability of the patellae. In later childhood, bony changes in the patellar groove interfere with stability, even if surgical realignment is performed. Realignment can also lead to increased knee pain postoperatively. In asymptomatic patients who are able to extend their knees, continued observation is the management of choice. Dugdale TW, Renshaw TS: Instability of the patellofemoral joint in Down syndrome. J Bone Joint Surg Am 1986;68:405-413.

Question 11

A 3-year-old patient with L3 myelomeningocele has bilateral dislocated hips. Management should consist of

Explanation

In patients with myelomeningocele, the presence of bilateral hip dislocation does not affect ambulation, bracing requirements, sitting ability, degree of scoliosis, or level of comfort. There is little evidence to support active treatment of bilateral hip dislocations in patients with myelomeningocele proximal to L4. Fraser RK, Hoffman EB, Sparks LT, et al: The unstable hip and mid-lumbar myelomeningocele. J Bone Joint Surg Br 1992;74:143-146.

Question 12

A 4-year-old child sustains a spiral fracture to the tibia in an unwitnessed fall. History reveals three other fractures to long bones, and the parents are vague about the etiology of each. There is no family history of bone disease. The parents ask if the child has osteogenesis imperfecta (OI); however, there are no clinical or radiographic indications of this diagnosis. In addition to fracture care, management should include

Explanation

Child abuse and OI are frequently both in the differential diagnosis of a child with multiple fractures. If OI is suspected, testing is appropriate to confirm this diagnosis. This may include skull radiographs to look for wormian bones and/or fibroblast culturing and collagen analysis of a punch biopsy. Unfortunately, because of the large number of mutations that can yield the disease, DNA testing is not commercially available for OI. In this patient, however, the physician suspects nonaccidental trauma and is legally obligated in most states to notify child protective services. Because the child may be at considerable risk of further injury, hospitalization is indicated to protect the child until child protective services can complete a home investigation and assess the degree of risk. Work-up for both OI and child abuse can be done during the hospitalization. Rockwood CA, Wilkins KE, King RE (eds): Fractures in Children. Philadelphia, PA, JB Lippincott, 1984, vol 3, pp 173-175. Kempe CH, Silverman FN, Stelle BF, Droegemueller W, Silver HK: The battered-child syndrome. JAMA 1962;181:17-24.

Question 13

A 10-year-old girl has been unable to walk for the past 5 days because of bilateral hip pain. Administration of IV morphine has provided some pain relief. She is afebrile. History reveals that she had an upper respiratory tract infection 3 weeks ago that resolved uneventfully. Examination reveals moderate pain with internal rotation and abduction, while log rolling maneuvers do not cause significant pain. An MRI scan shows a small effusion of one hip; however, a bone scan and plain radiographs are normal. Initial laboratory studies showed a markedly elevated WBC count, which subsequently declined to normal levels with IV antibiotics. Current studies show an erythrocyte sedimentation rate (ESR) of 100 mm/h. Aspiration of the hip obtains 3 mL of fluid; Gram stain is negative for bacteria, but a cell count shows a WBC count of 16,500/mm3. Streptozyme titer of the peripheral blood is 200 units (normal is less than 100 units). Management should now consist of

Explanation

This clinical situation requires careful analysis because some data suggest infection and some a noninfectious inflammatory process. Bilateral hip involvement, the absence of significant fluid collection or fever, the streptozyme level, and the history of upper respiratory infection all suggest poststreptococcal toxic synovitis as the most likely cause for the clinical presentation. In the first 24 hours, this type of presentation might warrant incision and drainage given uncertainty of the diagnosis and the risks associated with missing an infection. However, 5 days after onset, surgery is not warranted, especially given that the patient remains afebrile and her symptoms are improving. Cardiology consultation would be appropriate. There is no evidence to suggest slipped capital femoral epiphysis. Treatment with antibiotics is not advised because there is no bacteriologic data on which to base treatment. De Cunto CL, Giannini EH, Fink CW, et al: Prognosis of children with poststreptococcal reactive arthritis. J Pediatr Infect Dis 1988;7:683-686.

Question 14

What is the best initial screening test for a patient with a limb-length discrepancy?

Explanation

With the patient standing, add blocks under the short leg until the pelvis is level, then measure the blocks to determine the discrepancy. This method is an accurate, simple, and inexpensive way to assess limb-length discrepancy. Differences of less than 2 cm need no treatment. Increasing discrepancy in a growing child should be followed clinically. Radiographic examination can include scanography, CT scanography, or a standing pelvic radiograph with the pelvis leveled. CT scanography is the most accurate diagnostic test when hip, knee, or ankle contractures are present. Herring JA: Tachdjian's Pediatric Orthopedics, ed 4. Philadelphia, PA, WB Saunders, 2002, pp 1041-1045. Schoenecker PL, Rich MM: The lower extremity, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, pp 1120-1122. Stanitski DF: Limb-length inequality: Assessment and treatment options. J Am Acad Orthop Surg 1999;7:143-153.

Question 15

A 6-year-old girl has never been able to crawl or walk and can sit only when propped. History reveals no complications during pregnancy or delivery. Examination reveals a 30-degree scoliosis from T4 to L3. Deep tendon reflexes are absent, but fasciculations are present. The most likely genetic defect is the result of an abnormality in

Explanation

The patient's findings are consistent with an intermediate form of spinal muscular atrophy. Children with this condition appear normal at birth but are not able to walk. The disorder affects anterior horn cells. Fasciculations may be present, but deep tendon reflexes are typically absent. The development of scoliosis is almost universal with this type of spinal muscular atrophy. More than 90% of patients with spinal muscular atrophy have deletions in the telomeric survival motor neuron gene. Peripheral myelin protein 22 is abnormal in Charcot-Marie-Tooth type IA. Connexin 32 is abnormal in the X-linked type of Charcot-Marie-Tooth disease. Neurofibromin is affected in neurofibromatosis type 1. Friedreich's ataxia is secondary to a disorder of frataxin. Buckwalter JA, Einhorn TA, Simon SR (eds): Orthopaedic Basic Science, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 111-131.

Question 16

Figure 18a shows the clinical photograph of a 2-year old boy who has a deformity of the right leg. Examination reveals eight cutaneous markings similar to those shown in Figure 18b. Radiographs are shown in Figure 18c. Management should consist of

Explanation

18b 18c The diagnosis of neurofibromatosis may be based on the presence of at least six cafe-au-lait spots larger than 5 mm in diameter and the osseous lesion shown in Figure 18c. Neurofibromatosis occurs in 50% of patients who have an anterolateral bowing deformity of the tibia, and this bowing may be the first clinical manifestation of this disorder. The patient has anterolateral bowing of the tibia and fibula that warrants concern for a possible fracture and pseudarthrosis; therefore, the limb should be protected in a total contact orthosis to prevent fracture. In contradistinction to posteromedial bowing of the tibia and fibula, spontaneous remodeling of an anterolateral bowing deformity is not expected. Intramedullary nailing or the use of a vascularized fibula is reserved for the treatment of a congenital pseudarthrosis of the tibia. Crawford AH Jr, Bagamery N: Osseous manifestations of neurofibromatosis in childhood. J Pediatr Orthop 1986;6:72-88.

Question 17

What is the most common problem seen following epiphysiodesis for limb-length discrepancy?

Explanation

Errors in timing are by far the most common in this technically safe procedure. Incomplete growth arrest has been reported in up to 15% of patients versus timing errors in 61%. Fracture through the site has been reported rarely. Neurovascular and cartilaginous injury are extremely uncommon but always need to be considered when performing surgery in the vicinity of these structures. Blair VP III, Walker SJ, Sheridan JJ, Schoenecker PL: Epiphysiodesis: A problem of timing. J Pediatr Orthop 1982;2:281-284.

Question 18

Figure 19 shows the radiograph of a 6-month-old infant who has limited hip motion. History reveals no complications during pregnancy or delivery. Examination reveals that hip abduction is 45 degrees in flexion bilaterally. The neurologic examination is normal. What is the best course of action?

Explanation

Diminished hip abduction can occur in normal children and is not always associated with hip pathology; therefore, initial management should consist of observation.

Question 19

A 6-year-old boy with spastic diplegic cerebral palsy has a crouched gait. Examination reveals hip flexion contractures of 15 degrees and popliteal angles of 70 degrees. Equinus contractures measure 10 degrees with the knees extended. Which of the following surgical procedures, if performed alone, will worsen the crouching?

Explanation

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

Question 20

The parents of a 13-year-old boy with Down syndrome report that he has an increasing limp and decreased endurance with activities. Lateral flexion-extension radiographs of the cervical spine show no evidence of instability. Examination reveals a right Trendelenburg limp and an obvious limb-length discrepancy. Hip motion is symmetric except for some decreased abduction on the right side. A standing AP radiograph is shown in Figure 20. Management should consist of

Explanation

Ligamentous laxity and muscle hypotonia seen in Down syndrome contribute to the incidence of hip subluxation and dislocation. These factors can be progressive and lead to degenerative arthritis in adults with Down syndrome. Because this patient has a progressive limp and decreased endurance, observation and a shoe lift are not options. Bracing may be an option in the younger child before significant bony changes occur. Surgical intervention is the treatment of choice in this patient; however, all components of the deformity need to be addressed. Because of the increased capsular laxity, there is a high likelihood of recurrence if capsulorrhaphy is not included with the pelvic and femoral osteotomies. Surgery in these patients is associated with a high rate of complications. Shaw ED, Beals RK: The hip joint in Down's syndrome: A study of its structure and associated disease. Clin Orthop 1992;278:101-107. Aprin H, Zinc WP, Hall JE: Management of dislocation of the hip in Down's syndrome. J Pediatr Orthop 1985;5:428-431.

Question 21

A 9-year-old girl reports the immediate onset of severe groin pain and the inability to walk after tripping on a curb. Examination reveals marked hip pain with passive range of motion. A radiograph is shown in Figure 21. Regardless of treatment, what is the most common complication following this injury?

Explanation

The patient has an unstable slipped capital femoral epiphysis (SCFE). According to the classification system based on physeal stability, an unstable SCFE is one in which the patient is unable to walk, even with crutches. Ishemic necrosis, or osteonecrosis, of the femoral head is the most devastating complication of SCFE. One study found a 47% incidence of ischemic necrosis following unstable slips. This complication is most likely the result of vascular injury associated with initial femoral head displacement rather than the result of either tamponade from joint effusion or gentle repositioning prior to stabilization. Chondrolysis is a relatively uncommon complication following treatment of SCFE. This complication has been associated with persistent penetration of the hip joint with screws or pins used to stabilize the femoral head or with spica cast immobilization. There are no reports to suggest that osteochondritis dissecans, nonunion, or coxa magna follows treatment of SCFE. Loder RT, Richards BS, Shapiro PS, et al: Acute slipped capital epiphysis: The importance of physeal stability. J Bone Joint Surg Am 1993;75:1134-1140.

Question 22

An 8-year-old boy reports progressive difficulty with walking. Examination reveals muscle weakness, with proximal groups more affected than distal muscles. Deep tendon reflexes are within normal limits. Laboratory studies show a creatine kinase level of 7,200 IU. Based on these findings, what is the most likely diagnosis?

Explanation

Patients with Becker muscular dystrophy have an abnormality in dystrophin, but unlike patients with Duchenne muscular dystrophy, some dystrophin is present. As a result, the progression of muscle weakness is slower, with the diagnosis typically made after age 8 years. Similar to patients with Duchenne muscular dystrophy, patients with Becker muscular dystrophy have pseudohypertrophy of the calves, markedly increased creatine kinase levels, and X-linked transmission of the condition. In addition, these patients are more prone to cardiomyopathy; a condition that should be carefully evaluated if any surgery is required. Patients with spinal muscular atrophy also have proximal muscle weakness, but the onset of weakness occurs earlier in childhood. These patients also have absent deep tendon reflexes and fasciculations, but pseudohypertrophy is absent and creatine kinase levels are normal. Patients with Emery-Dreifuss dystrophy may have a similar clinical picture to Becker's muscular dystrophy, but pseudohypertrophy is absent and creatine kinase levels are only mildly elevated. In addition, neck extension, elbow flexion, and ankle equinus contractures develop at an early age. Limb girdle dystrophy is a group of progressive muscular dystrophies that is not associated with pseudohypertrophy or a significant elevation of creatine kinase levels. Guillain-Barre syndrome is a condition associated with results from postinfectious demyelination of the peripheral nerve. These patients have the acute onset of weakness, hypotonia, and areflexia; creatine kinase levels are normal. Sussman MD: Muscular dystrophy, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1573-1583.

Question 23

A 7-year-old boy sustained a 2-cm laceration to the anterior aspect of his left knee after falling on a rock. Examination reveals that the joint surface is not visible through the wound. Radiographs show no evidence of a foreign body or free air in the joint. Management should consist of

Explanation

The possibility of an open joint injury should be considered in any patient who has a small periarticular laceration. Failure to promptly diagnose and treat such injuries may lead to septic arthritis. The diagnosis of an open joint is easily made when there is visible communication of the joint through the traumatic wound, or when intra-articular air is present on a radiograph. In the absence of these findings, the diagnosis of an open joint may be established by the saline load test, in which a volume of saline is injected into the joint under sterile conditions. If fluid extravasates through the traumatic wound, the diagnosis of an open joint is established. Voit and associates used a saline load test in 50 patients with periarticular lacerations suggestive of joint penetration. When they compared the clinical prediction of whether or not the laceration had penetrated the joint and the test results, the authors reported a false-positive clinical result in 39% of patients and a false-negative clinical result in 43%. The authors concluded that the saline load test was valuable in evaluating periarticular lacerations. Voit GA, Irvine G, Beals RK: Saline load test for penetration of periarticular lacerations. J Bone Joint Surg Br 1996;78:732-733.

Question 24

What radiographic measurement is best used to assess the adequacy of deformity correction for the patient shown in Figure 22?

Explanation

Developmental coxa vara develops in early childhood and results in a progressive decrease in the proximal femoral neck-shaft angle with growth. The characteristic radiographic features are seen in this patient and include a decreased neck-shaft angle, a more vertical position of the physeal plate, and a triangular metaphyseal fragment in the inferior femoral neck, surrounded by an inverted radiolucent Y pattern. The main goal of surgery is to correct the varus angulation into a more normal range. Valgus overcorrection is preferred. A recent study emphasized the importance of adequately correcting the Hilgenreiner physeal angle to less than 38 degrees to minimize the risk of recurrent angulation. No study has documented the use of any of the other listed radiographic measurements to the outcome of treating developmental coxa vara. Carroll K, Coleman S, Stevens PM: Coxa vara: Surgical outcomes of valgus osteotomies. J Pediatr Orthop 1997;17:220-224.

Question 25

Figure 23 shows the radiograph of a 7 year-old girl with a low thoracic-level myelomeningocele. She has a history of skin ulcers over the apex of the deformity, but her current skin condition is good. Management of the spinal deformity should consist of

Explanation

This form of severe kyphosis results in intractable difficulties with sitting position, compression of internal organs, and chronic skin breakdown. Kyphectomy and posterior fusion with instrumentation, while associated with a high rate of complications, provides one of the best solutions to this clinical dilemma. The other choices are either completely ineffective or inadequate in managing this degree of deformity. Lindseth RE: Spine deformity in myelomeningocele. Instr Course Lect 1991;40:273-279.

Question 26

A 6-year-old boy presents with a completely displaced extension-type supracondylar humerus fracture. On examination, the hand is pink and warm, but the radial pulse is absent. Capillary refill is less than 2 seconds. What is the most appropriate next step in management?

Explanation

The pulseless, pink hand is a well-described clinical scenario in completely displaced supracondylar humerus fractures. The most appropriate initial step is urgent closed reduction and percutaneous pinning, followed by reassessment of the vascular status.

Question 27

A 12-year-old boy with a BMI of 32 presents with an acute-on-chronic stable left slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral asymptomatic hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated in patients with underlying endocrine disorders (such as hypothyroidism or renal osteodystrophy) or prior radiation therapy, as they are at a markedly increased risk of bilateral involvement.

Question 28

A 6-week-old girl is being treated with a Pavlik harness for developmental dysplasia of the hip. At her 2-week follow-up, she is noted to have decreased active extension of the knee on the treated side. Which of the following is the most appropriate next step?

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. Management consists of adjusting the anterior straps to decrease hip flexion or temporarily removing the harness if symptoms persist.

Question 29

A 13-year-old girl sustains an ankle injury. Radiographs, similar to the example shown, demonstrate a Salter-Harris III fracture of the anterolateral distal tibia.

Which of the following describes the typical sequence of physeal closure in the distal tibia that predisposes to this specific injury pattern?

Explanation

The distal tibial physis closes asymmetrically: first centrally, then posteromedially, then anteromedially, and lastly laterally. This leaves the anterolateral portion vulnerable to avulsion by the anterior inferior tibiofibular ligament (Tillaux fracture).

Question 30

A 3-year-old boy treated successfully in infancy for idiopathic clubfoot with the Ponseti method presents with recurrent dynamic supination of the foot during the swing phase of gait. Passive range of motion of the foot is normal. What is the most appropriate surgical management?

Explanation

Dynamic supination in a relapsed idiopathic clubfoot treated by the Ponseti method is best managed by transferring the entire anterior tibial tendon to the third (lateral) cuneiform. A SPLATT is typically reserved for spastic conditions such as cerebral palsy.

Question 31

An 11-year-old girl presents with an ill-defined, permeative lytic lesion in the diaphysis of the femur with a prominent soft tissue mass and "onion-skin" periosteal reaction. Biopsy confirms Ewing sarcoma. Which of the following chromosomal translocations is most commonly associated with this diagnosis?

Explanation

Ewing sarcoma is classically driven by the t(11;22)(q24;q12) chromosomal translocation. This creates the pathognomonic EWS-FLI1 fusion protein found in approximately 85% of cases.

Question 32

A 6-week-old female is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 1-week follow-up, the parents report she has stopped kicking her left leg. On examination, there is decreased active extension of the left knee, but normal ankle movements. What is the most appropriate next step in management?

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness should be temporarily removed until nerve function recovers.

Question 33

A 2-week-old infant presents with idiopathic clubfoot. The Ponseti method is initiated. What is the correct sequence of deformity correction during serial casting?

Explanation

The Ponseti method corrects the deformities in a specific sequence summarized by the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus.

Question 34

A 12-year-old boy presents with left knee pain and a limp. Radiographs confirm a stable left slipped capital femoral epiphysis (SCFE). Which of the following is the most accepted indication for prophylactic pinning of the contralateral asymptomatic hip?

Explanation

Prophylactic pinning of the contralateral hip is strongly considered in patients with underlying endocrine disorders, renal failure, or who are very young, due to a high risk of bilateral involvement.

Question 35

A 6-year-old boy sustains an extension-type Gartland III supracondylar humerus fracture. Examination reveals weakness in flexing 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 with an inability to form the "A-OK" sign.

Question 36

In a child with Legg-Calve-Perthes disease, which of the following radiographic findings during the fragmentation stage is considered a "head-at-risk" sign indicating a poorer prognosis?

Explanation

Catterall's "head-at-risk" signs include the Gage sign (V-shaped radiolucency in the lateral epiphysis/metaphysis), lateral calcification, lateral subluxation, and horizontal physis.

Question 37

Which of the following fracture patterns in a 4-month-old infant is most highly specific for non-accidental trauma?

Explanation

Posterior rib fractures, metaphyseal corner fractures, and scapular fractures are highly specific for child abuse (non-accidental trauma) in infants.

Question 38

An 8-month-old female presents with an untreated developmental dysplasia of the hip (DDH) with a dislocated left hip. What is the most appropriate initial management?

Explanation

For DDH presenting between 6 and 18 months of age, closed reduction and spica casting is the initial treatment of choice. The Pavlik harness is typically ineffective after 6 months of age.

Question 39

A 13-year-old boy presents with frequent ankle sprains and rigid flatfeet. Radiographs demonstrate an elongated anterior process of the calcaneus (anteater sign). Which of the following is the most likely diagnosis?

Explanation

The "anteater sign" refers to an elongated anterior process of the calcaneus, which is pathognomonic for a calcaneonavicular tarsal coalition on an oblique foot radiograph.

Question 40

According to established hip surveillance guidelines for children with cerebral palsy, which Gross Motor Function Classification System (GMFCS) level is associated with the highest risk of hip displacement?

Explanation

The risk of hip displacement in cerebral palsy increases with clinical severity. GMFCS Level V has the highest risk, with up to a 90% chance of progressive hip subluxation.

Question 41

A 3-year-old child sustains an isolated closed spiral fracture of the femoral shaft after a fall. The child weighs 16 kg (35 lbs). What is the most appropriate definitive treatment?

Explanation

For children between 6 months and 5 years of age weighing less than 20 kg (44 lbs), early spica casting is the treatment of choice for closed, isolated femoral shaft fractures.

Question 42

A 14-year-old girl sustains an ankle injury. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the mechanism of this injury?

Explanation

A Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It is caused by an external rotation force that avulses the bone via the anterior inferior tibiofibular ligament (AITFL).

Question 43

A 12-year-old premenarchal girl presents with adolescent idiopathic scoliosis. Her primary thoracic curve measures 25 degrees. Her Risser stage is 0. What is her approximate risk of curve progression to greater than 50 degrees?

Explanation

In a patient with Risser stage 0-1 and a curve of 20 to 29 degrees, the risk of curve progression is approximately 68%. Bracing is strongly indicated in this scenario.

Question 44

Osteogenesis imperfecta is most commonly caused by an autosomal dominant mutation affecting which of the following?

Explanation

Osteogenesis imperfecta is primarily caused by defects in Type I collagen due to mutations in the COL1A1 or COL1A2 genes, leading to bone fragility.

Question 45

A 3-year-old boy presents with progressive bilateral genu varum. Radiographs reveal an increased metaphyseal-diaphyseal angle (Drennan angle) of 18 degrees and medial metaphyseal beaking. What is the most likely diagnosis?

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees, combined with medial metaphyseal beaking in a young child, is highly predictive of infantile Blount disease rather than physiologic bowing.

Question 46

According to the Kocher criteria, which of the following is NOT one of the four classic predictors used to differentiate septic arthritis of the hip from transient synovitis in children?

Explanation

The original Kocher criteria include non-weight-bearing status, ESR > 40, WBC > 12,000, and Temp > 38.5C. CRP > 2.0 was later added by Caird to improve the predictive model but is not one of the original four.

Question 47

A 7-year-old girl presents with a painless snapping sensation in her lateral knee. MRI reveals a completely discoid lateral meniscus without any tears or instability. What is the most appropriate management?

Explanation

An asymptomatic or painlessly snapping discoid meniscus requires observation only. Surgical intervention is reserved for symptomatic tears or painful mechanical symptoms.

Question 48

An 8-year-old boy presents with a limp, fever, and refusal to bear weight on his right leg. Blood cultures are drawn and he is taken for aspiration and debridement of suspected acute hematogenous osteomyelitis. Which of the following organisms is the most common cause of this condition?

Explanation

Staphylococcus aureus is the most common causative organism for acute hematogenous osteomyelitis across all pediatric age groups.

Question 49

Children with achondroplasia are at highest risk for which of the following life-threatening neurologic complications during infancy?

Explanation

Infants with achondroplasia have a narrow foramen magnum, predisposing them to cervicomedullary compression. This can lead to central apnea and sudden death if not decompressed.

Question 50

A 9-year-old child sustains a displaced radial neck fracture with 45 degrees of angulation. Closed reduction attempts in the emergency department fail to improve the alignment. What is the next best step in management?

Explanation

Radial neck fractures with unacceptable angulation (>30-45 degrees) that fail closed reduction are best treated with percutaneous techniques, such as the Métaizeau retrograde intramedullary pinning method.

Question 51

A 10-year-old boy with wide open physes sustains a complete anterior cruciate ligament (ACL) tear. He experiences recurrent instability despite bracing and physical therapy. Which surgical technique is most appropriate to minimize the risk of growth arrest?

Explanation

In prepubescent children with significant remaining growth (Tanner stages 1 and 2), a physeal-sparing all-epiphyseal reconstruction is recommended to prevent premature physeal closure and angular deformity.

Question 52

A 14-year-old gymnast presents with persistent low back pain. Radiographs demonstrate a Grade II isthmic spondylolisthesis at L5-S1. She has failed 6 months of physical therapy and bracing. Which of the following is the most appropriate surgical intervention?

Explanation

For a symptomatic Grade II isthmic spondylolisthesis that has failed conservative management, an L5-S1 posterior spinal fusion is the standard of care. Direct pars repair is generally reserved for Grade I slips or isolated pars defects.

Question 53

An 18-month-old girl presents with a limp. Pelvic radiographs reveal a completely dislocated left hip with an acetabular index of 42 degrees. She has had no prior treatment. What is the most appropriate management plan?

Explanation

In a child older than 18 months with a completely dislocated hip and significant acetabular dysplasia (acetabular index >40 degrees), an open reduction combined with a pelvic osteotomy is typically required. Closed reduction has a high failure rate at this age due to soft tissue interposition and fixed bony deformity.

Question 54

A 13-year-old obese boy presents to the emergency department unable to bear weight on his right leg after a minor slip. He reports a 3-month history of mild right knee pain. Examination shows the right hip resting in external rotation. Which of the following complications is most highly associated with this acute presentation?

Explanation

This patient has an unstable slipped capital femoral epiphysis (SCFE), defined by the inability to bear weight. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 47%) compared to stable SCFE.

Question 55

A 4-year-old boy treated successfully in infancy for idiopathic clubfoot with the Ponseti method presents with an abnormal gait. Examination reveals dynamic supination of the foot during the swing phase of gait, with no fixed rigid deformities. What is the treatment of choice?

Explanation

Dynamic supination in a relapsed Ponseti-treated clubfoot without rigid deformity is best treated with a complete transfer of the tibialis anterior tendon to the lateral cuneiform. A split transfer is less effective for this specific relapse pattern.

Question 56

A 6-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. On arrival, the hand is pink and well-perfused, but the radial pulse is absent. What is the most appropriate next step in management?

Explanation

For a 'pink, pulseless' hand associated with a supracondylar humerus fracture, the initial treatment is urgent closed reduction and percutaneous pinning. If the hand remains well-perfused after pinning, vascular exploration is not indicated, and the patient can be closely observed.

Question 57

A 7-year-old girl with spastic quadriplegic cerebral palsy has bilateral hip pain. Pelvic radiographs show bilateral hip subluxation with a Reimers migration percentage of 60%. What is the most appropriate surgical intervention?

Explanation

In an older child with CP and severe hip subluxation (migration percentage >50%), soft tissue releases alone are insufficient. Bony reconstruction consisting of proximal femoral VDRO and pelvic osteotomy is required to restore joint congruity and prevent progression.

Question 58

A 4-year-old obese boy presents with bilateral progressive bowing of the legs. Radiographs demonstrate a metaphyseal-diaphyseal angle of 18 degrees and profound depression of the medial proximal tibial physis (Langenskiold stage III). What is the recommended treatment?

Explanation

Infantile Blount disease in a child older than 3 years with advanced changes (Langenskiold stage III) and a high metaphyseal-diaphyseal angle (>16 degrees) rarely responds to bracing. A proximal tibial valgus-producing and derotational osteotomy is indicated to correct the deformity.

Question 59

A 14-year-old boy presents with rigid, painful flatfeet and a history of recurrent ankle sprains. Computed tomography confirms a talocalcaneal coalition. If non-operative management is chosen first, what is the most appropriate initial intervention?

Explanation

Initial non-operative management for symptomatic tarsal coalition is aimed at reducing inflammation and pain by restricting subtalar motion. A short leg cast or rigid CAM boot immobilization for 3 to 6 weeks is the most effective first-line conservative treatment.

Question 60

A 2-year-old girl is evaluated for recurrent fractures following minimal trauma. Clinical examination reveals blue sclerae and dentinogenesis imperfecta. A defect in which of the following genes is most likely responsible?

Explanation

The patient's clinical presentation is classic for Osteogenesis Imperfecta (OI). OI is most commonly caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode type I collagen.

Question 61

A 7-year-old boy has been limping for 6 months and is diagnosed with Legg-Calve-Perthes disease. Radiographs show fragmentation of the femoral head. Which of the following radiographic findings represents the poorest prognostic factor?

Explanation

Lateral subluxation (extrusion) of the femoral head is a major "head at risk" sign and a poor prognostic factor in Perthes disease. It can lead to hinge abduction, resulting in severe deformity and early osteoarthritis.

Question 62

Congenital pseudarthrosis of the tibia (CPT) is most frequently associated with which of the following systemic conditions?

Explanation

Congenital pseudarthrosis of the tibia (CPT) is strongly associated with Neurofibromatosis type 1 (NF1), occurring in approximately 50% of patients with CPT. It typically presents as anterolateral bowing of the tibia that progresses to fracture and nonunion.

Question 63

A 12-year-old boy presents with thigh pain and a low-grade fever. Radiographs show a permeative diaphyseal lesion of the femur with an "onion-skin" periosteal reaction. Biopsy reveals sheets of small round blue cells. Which chromosomal translocation is highly diagnostic for this tumor?

Explanation

Ewing sarcoma is a small round blue cell tumor classically presenting with an "onion-skin" periosteal reaction in the diaphysis of long bones. It is highly associated with the t(11;22) chromosomal translocation, which results in the EWS-FLI1 fusion protein.

Question 64

A 3-year-old boy sustains an isolated, closed, spiral midshaft fracture of the right femur after a fall from a playground slide. He has no other injuries, and child abuse is not suspected. What is the most appropriate definitive management?

Explanation

For isolated femoral shaft fractures in children aged 6 months to 5 years with less than 2 cm of shortening, immediate hip spica casting is the gold standard. Flexible nailing is generally reserved for children aged 5 to 11 years or those with severe shortening/polytrauma.

Question 65

A 14-year-old girl presents with ankle pain after a twisting injury. Radiographs show a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. This injury (Tillaux fracture) is caused by avulsion from which of the following structures?

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs due to an external rotation force causing the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphysis, which is the last portion of the physis to close.

Question 66

A 14-year-old female gymnast with chronic back pain has failed 6 months of non-operative management. Radiographs reveal an isthmic spondylolisthesis at L5-S1 with a 60% anterior slip (Meyerding Grade III). What is the most appropriate surgical treatment?

Explanation

High-grade isthmic spondylolisthesis (Meyerding Grade III or higher, >50% slip) that is symptomatic and recalcitrant to conservative care requires surgical stabilization. L5-S1 or L4-S1 instrumented posterior spinal fusion, with or without reduction, is the standard of care.

Question 67

A 12-year-old obese boy presents to the emergency department with severe right groin pain and an inability to bear weight on his right leg after a minor fall. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). He undergoes urgent in situ pinning. Which of the following complications is most highly associated with this patient's specific type of presentation?

Explanation

This patient has an unstable SCFE, defined by the inability to bear weight even with crutches. Unstable SCFE has a significantly higher rate of avascular necrosis (up to 20-50%) compared to stable SCFE, regardless of the treatment method used.

Question 68

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During the follow-up visit, the parents report that the infant is no longer actively extending the knee on the treated side. On examination, there is decreased spontaneous movement of the quadriceps. What is the most appropriate next step in management?

Explanation

The infant presents with a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The appropriate management is to loosen the anterior straps to decrease hip flexion, which usually leads to spontaneous resolution of the palsy.

Question 69

A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease (LCPD). Which of the following factors at the time of presentation is considered the most significant predictor of a poor long-term radiographic outcome?

Explanation

Age at onset is a critical prognostic factor in LCPD; children older than 8 years generally have a worse prognosis and a higher risk of developing residual deformity and secondary osteoarthritis. The Herring Lateral Pillar classification is also highly prognostic, but Group A represents a good outcome.

Question 70

A 5-year-old girl falls from monkey bars and sustains a widely displaced, extension-type Gartland III supracondylar humerus fracture. On initial evaluation, the hand is pink and warm, but the radial pulse is not palpable. What is the most appropriate initial management?

Explanation

A "pulseless, pink" hand in the setting of a displaced supracondylar fracture should be managed with prompt closed reduction and percutaneous pinning (CRPP). Routine exploration is not required unless the hand becomes poorly perfused (white) after reduction.

Question 71

A 3-year-old boy sustains an isolated, closed, midshaft femur fracture with 2 cm of shortening. The child has no other injuries, and child abuse is not suspected. What is the gold standard of treatment for this patient?

Explanation

For children between the ages of 6 months and 5 years with an isolated diaphyseal femur fracture and less than 2-3 cm of shortening, early spica casting is the gold standard treatment. Flexible nailing is typically reserved for children aged 5 to 11 years.

Question 72

A 2-year-old child with a history of idiopathic clubfoot successfully treated with the Ponseti method presents with a dynamic supination deformity during the swing phase of gait. Passive range of motion is full, and the foot is completely correctable. What is the most appropriate surgical intervention?

Explanation

Relapsed clubfoot presenting as dynamic supination in a toddler with a flexible foot is best treated with a full transfer of the tibialis anterior tendon to the lateral cuneiform. This balances the foot by removing the supinating force and converting it to a dorsiflexing/everting force.

Question 73

A 30-month-old obese child presents with bilateral severe genu varum and a noticeable lateral thrust during gait. Radiographs show medial beaking of the proximal tibia. Which radiographic parameter most reliably differentiates infantile Blount disease from physiologic bowing?

Explanation

A metaphyseal-diaphyseal angle (Drennan's angle) of greater than 16 degrees on an AP radiograph is highly indicative of infantile Blount disease rather than physiologic genu varum. Angles less than 10 degrees usually resolve spontaneously.

Question 74

A 4-year-old boy presents with a 2-day history of right hip pain and a limp. He refuses to bear weight. His temperature is 38.8 C (101.8 F), ESR is 45 mm/hr, WBC count is 13,000/mm3, and serum CRP is 2.5 mg/dL. According to the classic Kocher criteria, what is the approximate probability that this child has septic arthritis?

Explanation

The child meets three of the four classic Kocher criteria (fever > 38.5 C, non-weight-bearing, ESR > 40, WBC > 12,000). The probability of septic arthritis with 3 criteria is approximately 93%.

Question 75

A 5-year-old girl is evaluated for multiple long bone fractures following minimal trauma. Clinical examination reveals blue sclerae and opalescent, abnormally worn teeth. Mutations in which of the following genes are the most common cause of her condition?

Explanation

The patient has osteogenesis imperfecta (OI), classically associated with blue sclerae and dentinogenesis imperfecta. OI is most commonly caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode type I collagen.

Question 76

An 8-year-old girl presents with a painless clicking and popping sound in her knee during extension. MRI reveals an abnormally thickened meniscus. The Wrisberg variant of this specific condition is characterized by the absence of which of the following stabilizing structures?

Explanation

The patient has a discoid meniscus. The Wrisberg variant lacks the normal posterior meniscotibial (coronary) ligaments, leaving the posterior horn hypermobile and attached only by the meniscofemoral ligament of Wrisberg.

Question 77

A 13-year-old boy sustains an ankle injury while playing soccer. Radiographs reveal a Salter-Harris type III fracture of the anterolateral aspect of the distal tibial epiphysis. What structure avulses this bone fragment during the injury mechanism?

Explanation

This describes a juvenile Tillaux fracture, which occurs due to an external rotation force. The fragment is avulsed by the tension of the anterior inferior tibiofibular ligament (AITFL) on the unfused anterolateral distal tibial epiphysis.

Question 78

A 14-year-old boy presents with a painful, rigid flatfoot and recurrent ankle sprains. Examination shows peroneal spasm. A lateral radiograph of the foot reveals a continuous "C-sign." This radiographic finding represents abnormal continuity between which of the following structures?

Explanation

The "C-sign" on a lateral radiograph is indicative of a talocalcaneal coalition. It represents the bony continuity between the medial outline of the talar dome and the posterior outline of the sustentaculum tali.

Question 79

A 10-year-old girl with widely open physes sustains a mid-substance anterior cruciate ligament (ACL) tear. Surgical reconstruction is planned. To minimize the risk of physeal arrest, particularly at the distal femur and proximal tibia, which technique is most appropriate?

Explanation

In prepubescent children with significant growth remaining (Tanner stage 1 or 2), a physeal-sparing (epiphyseal or extra-articular/intra-articular combination like the MacIntosh technique) reconstruction minimizes the risk of growth arrest by avoiding drilling across the open physes.

Question 80

A 6-year-old boy is evaluated for an acute fracture through the growth plate of a major long bone. Which of the following physeal fracture locations carries the highest intrinsic incidence of premature physeal closure, even in the setting of non-displaced Salter-Harris I and II patterns?

Explanation

The distal femoral physis has a unique undulating shape, making it highly susceptible to crushing forces during injury. Consequently, even low-grade Salter-Harris fractures (I and II) here have an unexpectedly high rate of premature growth arrest (up to 40-50%).

Question 81

Figure 37 shows a radiograph of a 13-year-old presenting with hip pain.

To assess for the condition seen, a line is drawn along the superior aspect of the femoral neck. In a normal hip, this line intersects the lateral aspect of the epiphysis. What is the eponymous sign when this line fails to intersect the epiphysis?

Explanation

The line described is Klein's line. In slipped capital femoral epiphysis (SCFE), Klein's line passes completely superior to the epiphysis rather than intersecting it; this finding is known as the Trethowan sign.

Question 82

A 12-year-old non-ambulatory boy with Duchenne muscular dystrophy (DMD) has developed a progressive scoliosis of 35 degrees. His forced vital capacity (FVC) is 45% of predicted. What is the most widely accepted orthopaedic management for this patient's spinal deformity?

Explanation

In Duchenne muscular dystrophy, spinal deformity is relentlessly progressive once the patient becomes wheelchair-bound. Bracing is ineffective and poorly tolerated. Early posterior spinal fusion extending to the pelvis is indicated to maintain sitting balance and optimize pulmonary function.

Question 83

A 9-year-old male soccer player presents with bilateral posterior heel pain. The pain worsens with activity and is relieved by rest. Examination reveals a positive "squeeze test" with pain on mediolateral compression of the posterior calcaneus. What is the primary pathophysiologic mechanism of this condition?

Explanation

The patient has Sever disease (calcaneal apophysitis). This is an overuse injury caused by repetitive microtrauma and traction from the Achilles tendon on the relatively weak calcaneal apophysis before it fuses.

Question 84

A newborn is evaluated in the nursery for a significantly shortened left lower extremity. The hip is maintained in a flexed, abducted, and externally rotated position. Radiographs reveal a severe deficiency of the proximal femur. Which of the following congenital anomalies is most commonly associated with this presentation?

Explanation

The clinical presentation describes proximal femoral focal deficiency (PFFD). Fibular hemimelia is the most common associated longitudinal deficiency seen in patients with PFFD, occurring in approximately 50% to 70% of cases.

Question 85

A 6-year-old child with spastic quadriplegic cerebral palsy is found to have a Reimer's migration percentage of 45% on a screening AP pelvis radiograph. Spasticity in which specific muscle groups is the primary deforming force leading to hip subluxation in this patient population?

Explanation

In cerebral palsy, progressive hip subluxation and dislocation are driven by the muscle imbalance primarily caused by spasticity and contracture of the hip adductors and hip flexors (iliopsoas). This forces the hip into adduction and flexion, levering the femoral head out of the acetabulum.

Question 86

A 9-month-old boy is referred for a left-sided thoracic scoliosis. Upright radiographs demonstrate a 25-degree curve. Measurement of the rib-vertebra angle difference (RVAD) of Mehta at the apical vertebra is 25 degrees. Based on these findings, what is the most likely natural history and the appropriate next step in management?

Explanation

Infantile idiopathic scoliosis with a rib-vertebra angle difference (RVAD) greater than 20 degrees is highly likely to progress (Phase 2 curve). The standard early management for progressive infantile curves is serial corrective casting (Mehta casting) to harness growth and correct the deformity.

Question 87

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, it is noted that the harness is adjusted with excessive hip flexion. This specific malposition is most associated with which of the following complications?

Explanation

Excessive hip flexion in a Pavlik harness can cause impingement leading to a femoral nerve palsy. In contrast, excessive abduction is classically associated with avascular necrosis of the femoral head.

Question 88

A 13-year-old obese boy presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. What is the most established primary indication for prophylactic pinning of the asymptomatic contralateral hip?

Explanation

Prophylactic pinning of the contralateral hip is generally recommended for patients younger than 10 years or those with underlying endocrine disorders (e.g., hypothyroidism). These patients have a significantly higher risk of developing bilateral involvement.

Question 89

An 8-year-old boy with Legg-Calve-Perthes disease presents with hip pain and a limp. Radiographs reveal greater than 50% maintenance of the lateral pillar height (Herring B). According to the Herring lateral pillar classification, what is the most appropriate management?

Explanation

For patients 8 years and older with Herring group B or B/C border Perthes disease, surgical containment (pelvic or femoral osteotomy) is indicated. This approach yields better radiographic and clinical outcomes compared to nonoperative treatment in this older age group.

Question 90

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. After anatomic closed reduction and percutaneous pinning in the operating room, the hand is pink and capillary refill is brisk, but the radial pulse remains absent. What is the most appropriate next step in management?

Explanation

A pulseless but pink and well-perfused hand following adequate reduction and pinning of a supracondylar humerus fracture is an indication for close clinical observation and admission. Vascular exploration is only indicated if the hand remains white, cool, and poorly perfused after reduction.

Question 91

A 3-year-old girl presents with progressive bowing of her left leg. A clinical radiograph demonstrates medial physeal sloping and metaphyseal beaking.

Which radiographic measurement is most predictive of progression in this condition?

Explanation

The clinical scenario and imaging suggest infantile Blount's disease. A metaphyseal-diaphyseal angle (Drennan's angle) greater than 16 degrees on AP radiographs is highly predictive of progressive infantile tibia vara requiring treatment.

Question 92

A 3-year-old boy with a history of idiopathic clubfoot successfully treated with the Ponseti method presents with a recurrent deformity. Gait analysis reveals dynamic supination of the foot during the swing phase, but passive hindfoot range of motion is normal. What is the most appropriate treatment?

Explanation

Dynamic supination in a previously treated clubfoot with a supple hindfoot is best managed by transferring the entire anterior tibial tendon to the lateral cuneiform. A split transfer (SPLATT) is less effective for this specific condition and is usually reserved for neuromuscular disorders like cerebral palsy.

Question 93

A 9-year-old boy weighing 38 kg sustains an isolated, closed midshaft femur fracture. What is the current gold standard treatment modality for this patient?

Explanation

Flexible intramedullary nailing is the treatment of choice for length-stable femoral shaft fractures in school-aged children (5-11 years) weighing less than 50 kg. Rigid nailing via the piriformis is contraindicated in this age group due to the risk of avascular necrosis of the femoral head.

Question 94

A 14-year-old gymnast presents with chronic lower back pain and severe hamstring tightness. Radiographs reveal an L5-S1 isthmic spondylolisthesis with 60% anterior translation of L5 on S1 (Grade III). Nonoperative management has failed over 6 months. What is the most appropriate surgical intervention?

Explanation

For high-grade (Grade III or higher) isthmic spondylolisthesis in children, an L4-S1 fusion spanning the slip and the adjacent segment is recommended to prevent progression and reduce the high risk of pseudarthrosis. In situ posterolateral fusion is safe and has an excellent track record compared to aggressive reduction.

Question 95

A 5-year-old boy with recurrent fractures, blue sclerae, and dentinogenesis imperfecta is initiated on intravenous pamidronate therapy. Which of the following best describes the primary mechanism of action of this medication in this patient?

Explanation

Bisphosphonates like pamidronate act primarily by inducing apoptosis in osteoclasts, thereby inhibiting osteoclast-mediated bone resorption. This increases overall bone mineral density and decreases fracture burden in patients with osteogenesis imperfecta.

Question 96

A 12-year-old girl sustains a Salter-Harris type II fracture of the distal femur. She undergoes an anatomic closed reduction and percutaneous pinning. The parents are counseled regarding the prognosis. Which of the following complications is most notoriously common with this specific injury?

Explanation

Distal femur physeal fractures, regardless of displacement, have a very high rate of growth arrest (approaching 50%). This is due to the undulating, peg-and-groove anatomy of the distal femoral physis, which sustains severe crushing forces during injury.

Question 97

A 10-year-old boy sustains a completely displaced (Meyers and McKeever Type III) tibial eminence fracture during a bicycle accident. Closed reduction is attempted but is unsuccessful. Which of the following structures is most commonly entrapped, preventing an anatomic closed reduction?

Explanation

The anterior horn of the medial meniscus is the structure most frequently entrapped beneath a displaced tibial eminence fracture. This interposition blocks reduction and is a primary indication for arthroscopic or open surgical intervention.

Question 98

A 13-year-old boy presents with recurrent ankle sprains and rigid, painful flatfeet. A lateral radiograph of the foot demonstrates a prominent "C sign." Which of the following is the most likely diagnosis?

Explanation

The radiographic "C sign" is formed by the continuous bony outline of the medial talar dome and the sustentaculum tali, which is highly indicative of a talocalcaneal coalition. In contrast, a calcaneonavicular coalition typically presents with the "anteater nose" sign on an oblique radiograph.

AAOS Pediatric Orthopedic MCQs (Set 2): DDH, SCFE & Spinal Deformities | Board Review

Orthopedic Pediatrics 2026 MCQs: Board Review Questions & Answers (Part 2)

Key Takeaway

Orthopedic Pediatrics 2026 MCQs: Board Review Questions & Answers (Part 2)

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