ABOS Pediatric MCQs (Set 3): Fractures & DDH Questions

Question 1

Figures 29a and 29b show the radiographs of a 13-year-old competitive gymnast who has had elbow pain for the past 2 weeks. The pain is worse with tumbling activities. Examination reveals a mild effusion and slight limitation of extension and forearm rotation with no locking. Initial management should consist of

Explanation

The radiographs show a lesion in the capitellum that is consistent with osteochondritis dissecans. There is no evidence of a loose body at this time. Initial management should consist of cessation of gymnastic activities. Nonsteroidal anti-inflammatory drugs and ice may help to alleviate acute symptoms; most symptoms usually resolve in 6 to 12 weeks. The patient may then begin range-of-motion and strengthening exercises, with a slow return to activities once full range of motion and good strength have been achieved. However, the prognosis for a return to high-level competitive gymnastics is guarded. Surgery is indicated for intra-articular loose bodies, a locked elbow, or failure of nonsurgical management. Surgery may be done either open or arthroscopically. Loose bodies should be removed, and cartilage flaps should be debrided. The results of bone grafting and internal fixation generally have been poor. Drilling the base of the defect may stimulate replacement with fibrocartilage, but the benefits of this procedure are not well documented. Maffulli N, Chan D, Aldridge MJ: Derangement of the articular surfaces of the elbow in young gymnasts. J Pediatr Orthop 1992;12:344-350. Bauer M, Jonsson K, Josefsson PO, Linden B: Osteochondritis dissecans of the elbow: A long-term follow-up study. Clin Orthop 1992;284:156-160.

Question 2

A 12-year-old boy who has had a 1-month history of right thigh pain and a limp reports worsening of the pain after a fall, and he can no longer walk or bear weight on the involved extremity. Radiographs of the pelvis reveal a slipped capital femoral epiphysis with moderate to severe displacement. While positioning the patient on the fracture table for screw fixation, partial reduction of the slip is achieved. No further reduction maneuvers are attempted, and the epiphysis is stabilized with a single cannulated screw. What complication is most likely to develop following this procedure?

Explanation

Traditional classification of slipped capital femoral epiphyses is based on the following temporal criteria: acute (symptoms that persist for less than 3 weeks); chronic (symptoms that persist for more than 3 weeks); or acute on chronic (acute exacerbation of long-standing symptoms). A newer classification differentiates between a stable slip where weight bearing is possible, and an unstable slip if it is not. Reduction of an unstable slip often occurs unintentionally with induction of anesthesia and positioning of the patient for surgery. The rate of satisfactory results is lower primarily because of a much higher incidence of osteonecrosis following internal fixation of an unstable slip. Loder RT, Richards BS, Shapiro PS, Reznick LR, Aronson DD: Acute slipped capital femoral epiphysis: The importance of physeal stability. J Bone Joint Surg Am 1993;75:1134-1140.

Question 3

Figure 30 shows the AP radiograph of a 9-month-old girl who has been referred for evaluation of unequal leg lengths. Examination reveals symmetrical abduction of the hips. When the hips are flexed 90 degrees, the right knee height is greater than the left knee. The girth of the right thigh and calf is larger than the contralateral side. There are no cutaneous lesions, and examination of the spine is normal. The infant is moving all extremities equally and spontaneously. Management should consist of

Explanation

Hemihypertrophy or hemihypotrophy is usually idiopathic, and either the leg or the entire side of the body may be involved. In the infant or young child, it is often difficult to determine which side is abnormal if the condition is mild. Because of the association of Wilms' tumor with hemihypertrophy, these patients should undergo a yearly renal ultrasound until at least age 5 years. Other conditions that may exhibit hemihypertrophy include Klippel-Trenaunay-Weber syndrome, Proteus syndrome, and neurofibromatosis. In this patient, the mild hemihypertrophy is idiopathic. Because of the normal spinal examination and absence of neurologic findings, an MRI scan is unnecessary. The absence of clinical and radiographic evidence of hip dysplasia makes both an ultrasound of the hips and application of a Pavlik harness unnecessary. Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont Ill, American Academy of Orthopaedic Surgeons, 1996, pp 185-193. Sponseller PD: Localized disorders of bone and soft tissue, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 305-344.

Question 4

What is the mechanism of action of an intramuscular injection of botulinum type A toxin in reducing spasticitiy?

Explanation

The use of intramuscular botulinum type A toxin has been shown to be a useful adjuvant in the management of dynamic deformity in patients with cerebral palsy. Botulinum type A toxin is a neurotoxin produced by Clostridium botulinum that works by interfering with presynaptic acetylcholine release at cholinergic nerve terminals. At the cellular level, the mechanism involves endocytosis of the intact botulinum toxin molecule by cells in the end plate, followed by disulfide cleavage and translocation of the light chain into the cytosol where it disrupts the normal binding of the synaptosomal vesicles to the axon terminal membrane. Neither the nerve terminal nor the neuromuscular junction is damaged. The muscle paralysis is reversible and dose-dependent. Baclofen is a neuropharmacologic agent that functions as a GABA agonist. Dorsal rhizotomy is a neurosurgical procedure that reduces spasticity by dividing afferent (excitatory) fibers in the posterior rootlet of the spinal nerves. Koman LA, Mooney JF III, Smith B, Goodman A, Mulvaney T: Management of cerebral palsy with botulinum-A toxin: Preliminary investigation. J Pediatr Orthop 1993;13:489-495.

Question 5

A 5-year-old boy has had right hip pain and a limp for the past 3 months. Examination of the right hip reveals irritability and restricted abduction and internal rotation. AP and lateral radiographs of the hips are shown in Figures 31a and 31b. Initial management should consist of

Explanation

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

Question 6

Hamstring lengthening and posterior transfer of the rectus femoris will be most successful in a patient with cerebral palsy who has which of the following gait abnormalities?

Explanation

Children with cerebral palsy typically ambulate with a crouched gait characterized by excessive flexion of the hips and knees during stance. Many patients exhibit co-contracture of the quadriceps and hamstrings, causing a stiff-knee gait. Normally, the rectus femoris fires at the initiation of swing and in terminal swing through initial contact. Prolonged activity of the rectus femoris throughout the swing phase interferes with normal knee flexion. This contributes to a stiff knee during swing phase and prevents clearance of the foot. Lengthening of the hamstrings alone will not improve foot clearance. Hamstring lengthening is contraindicated when there is hyperextension during stance. Transfer of the rectus femoris to one of the knee flexors has been shown to improve knee flexion during swing by an average of 15 degrees. This allows improved foot clearance. Gage JR, Perry J, Hicks RR, Koop S, Werntz JR: Rectus femoris transfer to improve knee function of children with cerebral palsy. Dev Med Child Neurol 1987;29:159-166.

Question 7

Figures 32a and 32b show the radiographs of a 13-year-old boy who sustained a fracture while playing football 1 week ago. Management at the time of injury included application of a cast and the use of crutches. A follow-up office visit reveals a normal neurologic examination, and the patient reports no discomfort with the cast and crutches. Management should now include

Explanation

Stable fractures and minimally displaced fractures in children can and should be treated by closed methods. Because loss of reduction is common, alignment of tibia fractures must be monitored closely for the first 3 weeks after cast application. This is most easily handled in a cooperative patient by cast wedging. Some children require application of a second cast under general anesthesia 2 to 3 weeks after injury, particularly if the subsidence of swelling has caused the cast to loosen. Surgical indications include the presence of soft-tissue injuries, unstable fracture patterns, fractures associated with compartment syndrome, and the child with multiple injuries. Surgical options in children include percutaneous pins, external fixation, plates and screws, and intramedullary nails. Heinrich SD: Fractures of the shaft of the tibia and fibula, in Rockwood CA, Wilkins KE, Beaty JH (eds): Fractures in Children, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 1340-1346.

Question 8

A 14-year-old patient with an L3 myelomeningocele underwent anterior and posterior spinal fusion for a curve of 50 degrees. Follow-up examination 1 week after the procedure now reveals persistent drainage from the posterior wound. Results of laboratory cultures show Streptococcus viridans, Staphylococcus aureus, and Enterococcus. In addition to IV antibiotics, surgical irrigation, and debridement, management should include

Explanation

The rate of wound infections has dramatically decreased with the routine use of prophylactic antibiotics. Factors known to increase the risk of infection include instrumentation, prolonged surgical time, excessive blood loss, poor perioperative nutritional status, a history of surgery, and a history of infection. The use of allograft does not result in an increased rate of infection. Adequate treatment requires early diagnosis and intervention. Temperature elevation and persistent wound drainage are highly suspicious for infection. An erythrocyte sedimentation rate and a WBC are not useful in diagnosis unless serial examinations show rising levels. Patients should be taken to the operating room where the entire wound can be reopened, irrigated, and debrided. Bone graft can be washed and replaced. Hardware should not be removed. The wound should be closed over suction drains. IV antibiotics should be given for a period of at least 10 days, followed by 6 weeks orally. Leaving the wound open to granulate with dressing changes results in prolonged hospitalization, inadequate treatment of the infection, and a poor cosmetic result. Lonstein JE: Complications of treatment, in Bradford DS, Lonstein JE, Moe JH, et al (eds): Moe's Textbook of Scoliosis and Other Spinal Deformities, ed 2. Philadelphia, Pa, WB Saunders, 1987, p 476.

Question 9

What is the primary mechanism of injury for the fracture shown in Figures 33a and 33b?

Explanation

The radiographs show a triplane fracture of the ankle. In adolescence, closure of the distal tibial physis starts peripherally at the anteromedial aspect of the medial malleolus and extends posteriorly and laterally. The anterolateral quadrant of the physis is the last to close, making this region the most susceptible to separation. When the foot is twisted into external rotation, the anterolateral portion of the epiphysis is avulsed by the pull of the anterior tibiofibular ligament. When this fragment alone is avulsed, the result is a juvenile Tillaux fracture. When the fracture extends to involve the remainder of the physis and posterior metaphysis, as in this patient, the result is a triplane fracture. Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1996, pp 267-272. Dias LS, Giegerich CR: Fractures of the distal tibial epiphysis in adolescence. J Bone Joint Surg Am 1983;65:438-444.

Question 10

Figure 34 shows the standing AP radiograph of a 2-year-old girl who has a left bowleg deformity. Her mother states that she first noticed the problem when the child began walking at age 10 months, and the deformity has worsened over the past 6 months. Examination reveals a definite lateral thrust of the knee during the stance phase of gait. Management should consist of

Explanation

Infantile tibia vara is a developmental condition characterized by a varus angulation of the proximal end of the tibia that is caused by a growth disturbance of the proximal medial physis. In a study of 42 affected extremities in 24 children younger than age 3 years, it was found that daytime ambulatory brace treatment favorably altered the natural history of tibia vara. Another study of 27 patients with stage II Langenskiöld disease found a success rate of 70% (improved alignment without the need for osteotomy) using brace treatment. These authors also noted that children with unilateral disease were more likely to obtain correction of the deformity compared with those with bilateral disease. In this patient, observation is not warranted because untreated tibia vara has a significant risk for progressive worsening. Osteotomy is best reserved for those patients who, despite bracing, do not show satisfactory clinical and radiographic improvement by age 4 years. Elevation of the medial tibial plateau is a treatment option for older patients who have more advanced disease. An MRI scan would not provide any useful clinical information at this time. Zionts LE, Shean CJ: Brace treatment of early infantile tibia vara. J Pediatr Orthop 1998;18:102-109. Richards BS, Katz DE, Sims JB: Effectiveness of brace treatment in early infantile Blount's disease. J Pediatr Orthop 1998;18:374-380.

Question 11

Figures 35a and 35b show the radiographs of a 7-year-old patient who has progressive deformity of the right thigh accompanied by a dull persistent pain radiating to the knee. Examination reveals an obvious bulge in the right thigh, with flexion of the hip beyond 50 degrees only if the hip is allowed to externally rotate. Management should consist of

Explanation

The patient has radiographic signs of osteogenesis imperfecta, including osteopenia, mild acetabular protrusio, cortical thinning, and bowing associated with anterior stress fracturing. The treatment of choice is correction of the bow with osteotomies, followed by intramedullary fixation to prevent further deformity. Biphosphonates, such as pamidronate, may be useful in increasing bone density and preventing fractures. Large multicenter studies on biphosphonate efficacy are currently in progress. Zionts LE, Ebramzadeh E, Stott NS: Complications in the use of the Bailey-Dubow extensible nail. Clin Orthop 1998;348:186-195. Luhmann SJ, Sheridan JJ, Capelli AM, Schoenecker PL: Management of lower-extremity deformities in osteogenesis imperfecta with extensible intramedullary rod technique: A 20-year experience. J Pediatr Orthop 1998;18:88-94.

Question 12

Figures 36a and 36b show the MRI scans of a 15-year-old girl who has had pain and recurrent hemarthrosis in the knee for the past year. Plain radiographs are normal. What is the most likely diagnosis?

Explanation

In pediatric patients who have pain and recurrent hemarthrosis in the knee, hemangioma is often seen as an internal derangement of the knee, and long delays in diagnosis are common. An MRI scan is noninvasive and will best aid in diagnosis. In this patient, the MRI scan shows a hemangioma with no evidence of meniscal injury or discoid meniscus. Hemophilia is unlikely because the patient is female. The presence of hemarthrosis makes JRA an unlikely diagnosis.

Question 13

A 2-year-old child has marked hypotonia and depressed reflexes. History reveals that the child was normal at birth and developed normally for the first year. The child also began to ambulate, but lost this ability during the next 6 months. Laboratory studies show a creatine phosphokinase level that is within the normal range. DNA testing confirms a deletion in the survival motor neuron (SMN) gene. What is the most likely diagnosis?

Explanation

The patient has spinal muscular atrophy, type 2. This type is intermediate in severity between the Werdnig-Hoffmann type (type 1) and the Kugelberg-Welander type (type 3). It normally manifests itself between the ages of 3 and 15 months. Survival until adolescence is common. All three types of spinal muscular atrophy have been linked to the SMN gene at the 5q12.2-13.3 locus. DNA testing is available and is preferred to muscle biopsy because it is less invasive and more definitive. Biros I, Forrest S: Spinal muscular atrophy: Untangling the knot? J Med Genet 1999;36:1-8.

Question 14

A 13-year-old boy sustains a valgus stress injury to the knee while playing football, and he is unable to bear weight after the injury. Examination reveals tenderness medially superior to the joint line. The knee is held in flexion, and he has a large effusion and localized medial swelling. Plain radiographs show no obvious fracture. What is the next diagnostic step?

Explanation

In the skeletally mature individual, this mechanism of injury will often result in a sprain of the medial collateral ligament. In skeletally immature patients, the same mechanism can cause a fracture of the distal femoral physis. If the fracture is nondisplaced, the plain radiographs may show only soft-tissue swelling or effusion. While the MRI scan may show edema in the soft tissues on the medial side of the knee and even an abnormality of the physis, stress radiographs provide a quicker and less expensive means of making the diagnosis. Arthroscopy and arthrography would not be helpful in making the diagnosis. Arthroscopy may result in further displacement of the injury. Smith L: Concealed injury to the knee. J Bone Joint Surg Am 1962;44:1659-1660.

Question 15

Figure 37 shows the clinical photograph of a 1-day-old infant who weighed 10.25 lb at birth. Examination reveals an absent right Moro reflex and limited active motion of the right shoulder, elbow, and wrist, but flexion of the fingers. Passive range of motion of the shoulder and elbow is normal. What is the most likely diagnosis?

Explanation

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

Question 16

Figure 38 shows the radiograph of a 5-year-old child who sustained a type III supracondylar fracture. Examination reveals the absence of a radial pulse, but an otherwise well-perfused hand. Following closed reduction and percutaneous pinning, the radial pulse remains absent; however, the hand is pink and well perfused. Management should now include

Explanation

In a study of over 400 patients with displaced supracondylar fractures, 3.2% of the fractures were associated with the absence of the radial pulse with an otherwise well-perfused hand. Based on this study, a period of close observation with frequent neurovascular checks should be completed before attempting invasive correction of the problem. Because of the satisfactory results with expectant management, angiography, exploration, removal of fixation and exploration, and thrombectomy are contraindicated.

Question 17

Figures 39a and 39b show the radiographs of an otherwise healthy 10-year-old boy who has had thigh pain and a limp for the past 9 months. Examination reveals that the left lower extremity is 1 cm shorter, with reduced flexion, abduction, and internal rotation on the left side. The patient is at the 50th percentile for height and the 90th percentile for weight. Serum studies will most likely show

Explanation

The patient has a slipped capital femoral epiphysis (SCFE) at a younger than average age (average age 13.5 years for boys and 12.0 years for girls); therefore, an etiology that is not idiopathic must be considered. Hypothyroidism can result in a SCFE, but these children typically fall into the category of less than the 10th percentile for height. SCFE may develop in children with a growth hormone deficiency who have undergone hormonal replacement. Osteodystrophy caused by chronic renal failure may result in a SCFE, but the bone quality is markedly osteopenic on radiographs and the children are chronically ill with both low height and weight percentiles. An elevated estrogen level results in physeal closure and is protective to physeal slippage. Therefore, this child will most likely have normal laboratory values. Loder RT, Hensinger RN: Slipped capital femoral epiphysis associated with renal failure osteodystrophy. J Pediatr Orthop 1997;17:205-211.

Question 18

A 7-year-old patient has had a painless limp for several months. Examination reveals pain and spasm with internal rotation, and abduction is limited to 10 degrees on the involved side. Management consists of 1 week of bed rest and traction, followed by an arthrogram. A maximum abduction/internal rotation view is shown in Figure 40a, and abduction and adduction views are shown in Figures 40b and 40c. The studies are most consistent with

Explanation

The radiographs show classic hinge abduction. The diagnostic feature is the failure of the lateral epiphysis to slide under the acetabular edge with abduction, and the abduction view shows medial dye pooling because of distraction of the hip joint. Persistent hinge abduction has been shown to prevent femoral head remodeling by the acetabulum. Radiographic changes are characteristic of severe involvement with Legg-Calve-Perthes disease.The Catterall classification cannot be well applied without a lateral radiograph, but this degree of involvement would likely be considered a grade III or IV. Because the lateral pillar is involved, this condition would be classified as type C using the Herring lateral pillar classification scheme.

Question 19

A 14-year-old football player has had thigh pain and weakness following a full-contact scrimmage 24 hours ago. He recalls that he felt a sharp pain in his back after colliding with a much heavier player. Examination reveals that the spine is minimally tender to palpation in the upper lumbar region. Motor testing reveals quadriceps weakness bilaterally, and a reverse straight leg raising test is positive. Plain radiographs of the thoracolumbar spine are normal. A myelogram, a CT scan with contrast, and an MRI scan are shown in Figures 41a through 41c. What is the most likely diagnosis?

Explanation

Fracture of the vertebral end plate is a relatively uncommon injury that is most often seen in adolescent boys. The injury is characterized by traumatic displacement of the vertebral ring-apophysis into the spinal canal and associated disk herniation. Over one third of these injuries are seen in children with lumbar Scheuermann disease. The injury most frequently involves the midlumbar vertebra, and symptoms are often indistinguishable from those associated with a herniated disk. The injury is usually not visible on plain radiographs. The diagnosis is typically made after obtaining MRI or contrast CT scans. Treatment consists of laminotomy and excision of the osteochondral fragments. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 635-651.

Question 20

Figure 42 shows the radiograph of a 12-year-old boy who has a limp and pain in the left hip with athletic activity. Examination reveals decreased abduction and internal rotation of the left hip, with pain at the extremes of motion and a 1-cm limb-length discrepancy. Management should consist of

Explanation

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

Question 21

The mother of a 5-year-old child reports that he has had a fever of 103 degrees F (39.4 degrees C), leg swelling, and has been unwilling to bear weight on his right lower leg for the past 7 days. Examination reveals point tenderness at the distal femur. Aspiration at the metaphysis yields 10 mL of purulent fluid, and a Gram stain reveals gram-positive cocci. In addition to hospital admission, management should include

Explanation

The patient has a subperiosteal abscess. Because aspiration revealed 10 mL of purulent fluid, the treatment of choice is surgical incision and drainage of the abscess, followed by immobilization to reduce the risk of pathologic fracture. With an adequate response to IV antibiotics and a susceptible bacteria, the patient may then be switched to oral antibiotics.

Question 22

Figure 43 shows the lateral radiograph of a 12-year-old boy with mild osteogenesis imperfecta who injured his left elbow after pushing his brother. Treatment should consist of

Explanation

The patient has a displaced fracture of the apophysis of the olecranon for which most authorities recommend surgical treatment. In older children, stability of the reduction may be achieved by the use of two parallel medullary Kirschner wires and a figure-of-8 tension band loop of either stainless steel wire or absorbable suture. The use of an absorbable suture does not require removal of the implant. Absorbable suture alone is best used in very young patients who have this type of injury. An intramedullary screw would pose an unnecessary risk of future growth disturbance. A displaced, isolated fracture of the apophysis of the olecranon is an unusual injury in a child. It has been suggested by several authors that children who have osteogenesis imperfecta may be especially prone to this injury. One study reported seven of these fractures occurring in five children who had the mild form of osteogenesis imperfecta (Sillence type IA). The authors of this study suggest that the diagnosis of osteogenesis imperfecta be considered in any child who has a displaced fracture of the apophysis of the olecranon, especially when the injury is associated with relatively minor trauma. Stott NS, Zionts LE: Displaced fractures of the apophysis of the olecranon in children who have osteogenesis imperfecta. J Bone Joint Surg Am 1993;75:1026-1033. Gaddy BC, Strecker WB, Schoenecker PL: Surgical treatment of displaced olecranon fractures in children. J Pediatr Orthop 1997;17:321-324.

Question 23

Figure 44 shows the radiograph of an 11-year-old girl who has hip pain. Further diagnostic workup should include

Explanation

The patient has severe acetabular protrusio, a condition that is frequently associated with Marfan syndrome. An echocardiogram is necessary to rule out the most serious consequence of this syndrome, aortic root widening, which can lead to aortic valve dysfunction or fatal aortic rupture. An electromyogram may be indicated for Charcot-Marie-Tooth disease, which is associated with acetabular dysplasia, but not protrusio. The renal ultrasound, the MRI scan, and the biopsy would be of no value in this patient. Protrusio can also be seen in patients with osteogenesis imperfecta and juvenile rheumatoid arthritis. Steel HH: Protrusio acetabuli: Its occurrence in the completely expressed Marfan syndrome and its musculoskeletal component and a procedure to arrest the course of protrusion in the growing pelvis. J Pediatr Orthop 1996;16:704-718.

Question 24

Figure 45 shows the radiograph of a 2-year-old patient who has progressive lumbar scoliosis as the result of hemivertebra. Examination reveals no associated cutaneous lesions, and an MRI scan shows no associated intraspinal anomalies. Treatment should consist of

Explanation

In a retrospective review of 10 patients treated with hemivertebra excision for hemivertebra in the levels of T12 to L3, the procedure was found to be safe and effective. The procedure provided an average curve correction of 67 degrees and was greatest in patients who were younger than age 4 years at the time of surgery. Long anterior and posterior fusion with instrumentation is not the treatment of choice at this age. Either anterior hemiepiphyseodesis or posterior hemiarthrodesis in this isolated hemivertebra setting would be inadequate. Brace treatment is ineffective in management of the primary curvature.

Question 25

A 10-year-old girl with a history of an obstetrical brachial plexus palsy has been referred for evaluation. Examination reveals a severe adduction internal rotation contracture of the shoulder and a mild flexion contracture of the elbow. Hand function is normal. Radiographs show mild glenohumeral joint incongruity. To achieve the best functional outcome, management should consist of

Explanation

The patient has an upper plexus palsy (Erb palsy) with severe shoulder contracture. While physical therapy for stretching is the treatment of choice to prevent contracture in the newborn, it is unlikely to be of benefit in the older child with an established contracture. Contracture release alone or in combination with muscle transfers can improve the cosmetic appearance, and in the case of a mild deformity, may also improve function. These procedures are less likely to help when there is deformity of the shoulder joint or when arthritic changes are present. The procedure of choice for an older child with joint deformity is rotational osteotomy of the proximal humerus because it can improve cosmesis and function, even in the face of joint deformity. Jahnke AH Jr, Bovill DF, McCarroll HR Jr, James P, Ashley RK: Persistent brachial plexus birth palsies. J Pediatr Orthop 1991;11:533-537. Strecker WB, McAllister JW, Manske PR, Schoenecker PL, Dailey LA: Sever-L'Episcopo transfers in obstetrical palsy: A retrospective review of 20 cases. J Pediatr Orthop 1990;10:442-444.

Question 26

A 6-week-old female infant is currently being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). At her 2-week follow-up, the ultrasound reveals that the left hip remains dislocated. During the physical examination, you note that she has an absent patellar reflex on the left side and decreased spontaneous extension of the left knee. 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 most appropriate initial management is to discontinue the harness to allow for neurologic recovery, which typically resolves spontaneously.

Question 27

A 6-year-old boy sustains a completely displaced Gartland type III extension-type supracondylar humerus fracture. On initial presentation, his hand is pink but the radial pulse is not palpable. Following urgent closed reduction and percutaneous pinning, the fracture is anatomically aligned, but the hand remains pink and pulseless. Capillary refill is less than 2 seconds. What is the most appropriate management?

Explanation

A pink, pulseless hand post-reduction of a supracondylar humerus fracture with adequate perfusion (capillary refill < 2 seconds) should be observed. Collateral circulation is typically sufficient, and surgical exploration is reserved for hands that become or remain pale and poorly perfused after reduction.

Question 28

An 8-month-old boy is evaluated for infantile idiopathic scoliosis. Radiographs demonstrate a 25-degree left thoracic curve. According to Mehta's criteria, a Rib-Vertebra Angle Difference (RVAD) greater than which of the following values is most predictive of curve progression?

Explanation

Mehta described the Rib-Vertebra Angle Difference (RVAD) to predict progression in infantile idiopathic scoliosis. An RVAD > 20 degrees is highly associated with progressive curves and warrants treatment, such as serial derotational casting.

Question 29

A 14-year-old boy presents with an ankle injury after an external rotation force during football. Radiographs and a subsequent CT scan reveal a Salter-Harris type III fracture of the anterolateral aspect of the distal tibial epiphysis, with 3.5 mm of displacement. What anatomic structure is responsible for the avulsion of this specific fracture fragment?

Explanation

This is a juvenile Tillaux fracture, caused by avulsion via the anterior inferior tibiofibular ligament (AITFL). It occurs in adolescents because the distal tibial physis closes from central to anteromedial to posteromedial, leaving the anterolateral physis open last and susceptible to avulsion.

Question 30

During an open reduction of a late-presenting Developmental Dysplasia of the Hip (DDH) via a medial (Ludloff) approach, several anatomical structures blocking reduction can be accessed. Which of the following pathological obstacles to reduction CANNOT be adequately addressed through this approach?

Explanation

The medial approach accesses the inferior and medial obstacles to reduction, including the iliopsoas, transverse acetabular ligament, and ligamentum teres. It cannot safely access or address a redundant superior capsule or an inverted limbus, which require an anterior approach.

Question 31

A 12-year-old boy with Duchenne muscular dystrophy presents with a progressive, sweeping thoracolumbar neuromuscular scoliosis measuring 45 degrees. He became wheelchair-bound 6 months ago. His forced vital capacity (FVC) is 45% of predicted. What is the most appropriate definitive management for his spinal deformity?

Explanation

Surgical stabilization is indicated in Duchenne muscular dystrophy when curves reach 20-30 degrees in non-ambulatory patients to maintain sitting balance and pulmonary function. Fusion must routinely extend to the pelvis to address pelvic obliquity.

Question 32

A 9-year-old boy undergoes closed reduction and casting for a midshaft both-bone forearm fracture. During healing, he develops an angular malunion. Loss of which of the following anatomic features is most likely to significantly restrict his functional supination and pronation?

Explanation

The native lateral bow of the radius is critical for allowing the radius to rotate around the ulna during supination and pronation. Angular deformities that flatten or reverse the radial bow cause profound deficits in forearm rotation.

Question 33

A 35-year-old male presents with numbness in his small and ring fingers, along with intrinsic muscle weakness in his dominant hand. He reports a history of an elbow fracture treated non-operatively with a cast when he was 5 years old. Examination reveals significant valgus carrying angle at the elbow. Which of the following pediatric fracture patterns is most likely responsible for this late presentation?

Explanation

Pediatric lateral condyle fractures have a high risk of nonunion if displaced and treated non-operatively. A nonunion leads to progressive cubitus valgus deformity, which eventually causes stretching of the ulnar nerve and a tardy ulnar nerve palsy years later.

Question 34

In the evaluation of Adolescent Idiopathic Scoliosis using the Lenke classification, specific radiographic criteria are used to determine if a minor curve is structural. Which of the following findings correctly defines a proximal thoracic minor curve as structural?

Explanation

In the Lenke classification, a minor proximal thoracic or main thoracic curve is considered structural if the residual Cobb angle is >= 25 degrees on a side-bending radiograph, or if the regional kyphosis is >= 20 degrees.

Question 35

A 4-week-old female infant with a breech presentation history is referred for a developmental dysplasia of the hip (DDH) ultrasound. When obtaining a standard Graf coronal view, the sonographer must ensure a standard plane is captured. Which bony landmark must be clearly visualized to confirm a true standard coronal view?

Explanation

To calculate Graf alpha and beta angles accurately, a true standard coronal plane must be achieved. The three essential sonographic landmarks required are the lower limb of the bony ilium (straight edge), the labrum, and the osseous margin of the acetabular roof.

Question 36

An 8-year-old, 32 kg boy sustains an isolated, length-stable midshaft transverse femur fracture and undergoes treatment with titanium elastic nails. Which of the following is the most frequently encountered complication specific to this fixation method in this age group?

Explanation

The most common complication following the use of flexible intramedullary nails for pediatric femur fractures is soft tissue irritation and pain at the distal insertion site near the knee, often requiring nail removal once the fracture has healed.

Question 37

A 2-year-old child is being evaluated for congenital scoliosis. Radiographs reveal multiple vertebral anomalies. Which of the following patterns of vertebral malformation carries the highest risk for rapid, unrelenting curve progression?

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra provides maximal asymmetric growth potential. The tethered side cannot grow, while the contralateral side with an extra growth center (hemivertebra) grows rapidly, leading to the worst prognosis for progression.

Question 38

A 3-month-old female infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During her 2-week follow-up, the parents report she has stopped kicking her left leg. On examination, there is an absence of active knee extension on the left, but she flexes the hip and moves the toes spontaneously. What is the most appropriate next step in management?

Explanation

The clinical presentation is classic for a femoral nerve palsy, a known complication of extreme hip flexion in a Pavlik harness. The most appropriate initial management is to discontinue the harness to allow the nerve palsy to resolve, which typically occurs within a few days to weeks.

Question 39

A 14-month-old boy presents with a left thoracic curve.

The physician is evaluating the curve to determine the risk of progression. Which of the following is the most reliable radiographic prognostic factor for progression in infantile idiopathic scoliosis?

Explanation

Mehta's rib-vertebral angle difference (RVAD) is the most reliable predictor of curve progression in infantile idiopathic scoliosis. An RVAD greater than 20 degrees strongly correlates with progressive curves requiring intervention.

Question 40

A 6-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture.

He presents with an absent radial pulse but a well-perfused, pink hand. After closed reduction and percutaneous pinning, the hand remains pink, but the radial pulse remains non-palpable. Doppler signals are audible at the wrist. What is the most appropriate management?

Explanation

A 'pink, pulseless' hand following adequate reduction and pinning of a supracondylar humerus fracture indicates adequate collateral circulation. The standard of care is admission and close clinical observation for 24-48 hours rather than immediate surgical exploration.

Question 41

A 12-year-old boy presents with right elbow deformity and a history of a fracture at age 4 that was treated non-operatively. Examination reveals severe cubitus valgus and numbness extending to the palmar aspect of the small finger and ulnar half of the ring finger. This condition most likely resulted from nonunion of which of the following fractures?

Explanation

Nonunion of a lateral condyle fracture leads to progressive cubitus valgus. This angular deformity chronically stretches the ulnar nerve, resulting in tardy ulnar nerve palsy.

Question 42

A 2-year-old child is diagnosed with congenital scoliosis. Which of the following vertebral anomalies carries the highest probability of rapid, unrelenting curve progression?

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra represents the worst prognosis for congenital scoliosis. Growth is tethered on the concave side and accelerated by the extra growth plates on the convex side, leading to rapid progression.

Question 43

A 24-month-old girl presents with a painless limp. Examination demonstrates a positive Trendelenburg sign on the left.

Radiographs confirm a dislocated left hip with a false acetabulum and severe acetabular dysplasia. What is the most appropriate initial treatment?

Explanation

In a child older than 18-24 months presenting with an untreated, dislocated DDH, open reduction is almost always necessary due to adaptive soft tissue contractures. A concomitant pelvic osteotomy (e.g., Salter) is required to correct the secondary acetabular dysplasia.

Question 44

A 13-year-old girl twists her ankle. Radiographs reveal a Salter-Harris III fracture of the anterolateral aspect of the distal tibia. This specific fracture pattern (Juvenile Tillaux fracture) is primarily due to which of the following anatomical factors?

Explanation

A juvenile Tillaux fracture occurs due to the asymmetric closure of the distal tibial physis. The physis closes first centrally, then medially, and finally anterolaterally, leaving the anterolateral portion vulnerable to avulsion via the AITFL during external rotation.

Question 45

A 12-year-old premenarchal girl has a right thoracic curve of 32 degrees on standing posteroanterior radiographs. Her Risser stage is 0. What is the most appropriate management?

Explanation

Bracing is indicated for immature patients (Risser 0-2, premenarchal) with an idiopathic curve between 25 and 40 degrees. A full-time TLSO brace is the standard of care to prevent curve progression to surgical magnitude.

Question 46

A 14-year-old non-ambulatory male with spastic quadriplegic cerebral palsy presents with a 75-degree sweeping neuromuscular scoliosis and marked pelvic obliquity, causing difficulty with wheelchair seating. What is the recommended surgical intervention?

Explanation

In patients with severe neuromuscular scoliosis and significant pelvic obliquity, fusion must typically extend to the pelvis to correct the obliquity, provide a level foundation for sitting, and prevent the 'crankshaft' phenomenon or distal add-on over time.

Question 47

In an ultrasound evaluation of a 4-week-old infant's hip for developmental dysplasia,

what specific anatomic feature is quantified by the alpha angle?

Explanation

The alpha angle on a developmental hip ultrasound measures the bony roof of the acetabulum. An angle of 60 degrees or greater is considered normal (Graf Type I).

Question 48

A 3-year-old boy is brought to the emergency department after a fall while running, resulting in a closed spiral fracture of the femoral shaft. Non-accidental trauma has been definitively ruled out. What is the most appropriate definitive treatment?

Explanation

For children between 6 months and 5 years of age with an isolated, low-energy femoral shaft fracture and acceptable shortening (<2 cm), early hip spica casting is the gold standard of treatment.

Question 49

A 10-year-old boy presents with a stable slipped capital femoral epiphysis (SCFE) of the right hip. Under which of the following conditions is prophylactic pinning of the contralateral, asymptomatic hip most strongly indicated?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with underlying endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) or prior radiation, due to the exceptionally high risk of bilateral involvement.

Question 50

A 14-year-old boy sustains a triplane fracture of the distal tibia following a fall. By definition, this fracture complex involves fracture lines propagating through three distinct planes. Which of the following accurately describes these planes?

Explanation

A standard triplane fracture of the distal tibia consists of a coronal fracture through the posterior metaphysis, a transverse fracture through the physis, and a sagittal fracture through the epiphysis.

Question 51

A 9-year-old girl with Neurofibromatosis Type 1 (NF-1) has a sharp 45-degree thoracic kyphoscoliosis.

Radiographs demonstrate vertebral scalloping, spindling of the transverse processes, and penciling of the ribs. What is the most appropriate surgical treatment?

Explanation

The patient has dystrophic scoliosis secondary to NF-1. Because these curves are highly prone to rapid progression and pseudarthrosis with posterior fusion alone, a combined anterior and posterior spinal fusion is recommended.

Question 52

A 6-year-old boy sustains a completely displaced, overriding fracture of the distal third of the radius and ulna. Closed reduction under conscious sedation achieves 15 degrees of dorsal angulation and 1 cm of bayonet apposition in a well-molded long-arm cast. What is the most appropriate next step?

Explanation

In children under 9 years of age, complete displacement (bayonet apposition) of a distal third forearm fracture is perfectly acceptable as long as angulation is less than 15-20 degrees, due to massive remodeling potential. Attempting further reduction is unnecessary.

Question 53

When treating developmental dysplasia of the hip (DDH) with closed reduction and spica casting, maintaining the hip in forced, extreme abduction ('frog-leg' position) significantly increases the risk of which of the following complications?

Explanation

Forced abduction during spica casting compresses the cartilaginous femoral head against the acetabulum and compromises the medial circumflex femoral artery, leading to avascular necrosis. Hips should be immobilized in the 'human position' (hyperflexion, moderate abduction).

Question 54

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

Explanation

In a pulseless but well-perfused (pink) hand following reduction and pinning of a supracondylar humerus fracture, observation is recommended as collateral circulation is adequate. Exploration is indicated if the hand is pulseless and white (poorly perfused).

Question 55

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report she has stopped kicking her right leg. Examination reveals decreased active extension of the right knee, but she withdraws to pain. What is the most likely cause, and what is the appropriate management?

Explanation

Femoral nerve palsy is a known complication of Pavlik harness use, often due to hyperflexion. The appropriate management is temporary discontinuation of the harness until neurologic function returns.

Question 56

Which of the following factors represents the highest risk for curve progression in a 12-year-old girl with Adolescent Idiopathic Scoliosis (AIS)?

Explanation

Peak height velocity and maximal curve progression occur just before or during Risser 0 and open triradiate cartilages. An open triradiate cartilage is a strong predictor of high remaining growth potential and curve progression.

Question 57

A 5-year-old boy sustained a pediatric lateral condyle fracture of the distal humerus 2 years ago, which was treated non-operatively. He now presents with progressive cubitus valgus. Which of the following tardy nerve palsies is most likely to develop?

Explanation

Nonunion of a lateral condyle fracture can lead to progressive cubitus valgus. This deformity stretches the ulnar nerve behind the medial epicondyle, classically leading to tardy ulnar nerve palsy.

Question 58

A newborn girl with arthrogryposis multiplex congenita is found to have bilateral rigid, irreducible teratologic hip dislocations. What is the most appropriate management?

Explanation

Teratologic hip dislocations (e.g., in arthrogryposis or spina bifida) are rigid and fail conservative management like Pavlik harnesses. Open reduction is typically required and is usually performed prior to walking age.

Question 59

A 9-month-old boy is diagnosed with infantile idiopathic scoliosis. Radiographs show a 25-degree left thoracic curve. Which of the following radiographic parameters best predicts whether this curve will progress or spontaneously resolve?

Explanation

The Mehta Rib-Vertebra Angle Difference (RVAD) is critical in evaluating infantile idiopathic scoliosis. An RVAD greater than 20 degrees with phase 2 rib head overlap strongly predicts curve progression.

Question 60

A 13-year-old obese boy undergoes in-situ pinning for a unilateral stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral hip?

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with SCFE associated with an underlying endocrine disorder (like hypothyroidism or renal osteodystrophy) due to the high risk of bilateral involvement.

Question 61

A 2-year-old boy sustains a closed, isolated midshaft femur fracture. He is treated with early spica casting. Which of the following acceptable radiographic parameters is correct for this age group?

Explanation

In children aged 2 to 10 years, up to 15 mm of shortening is acceptable and expected to correct via overgrowth. Up to 15 degrees of varus/valgus and 20 degrees of anteroposterior angulation are generally acceptable limits.

Question 62

In the Lenke classification for Adolescent Idiopathic Scoliosis, a curve is considered "structural" if it fails to reduce to less than what Cobb angle on side-bending radiographs?

Explanation

According to the Lenke classification, a minor curve is structural if the Cobb angle is 25 degrees or greater on a side-bending radiograph, or if there is kyphosis of +20 degrees or more across the region.

Question 63

An 11-year-old boy presents with progressive ulnar deviation of the wrist 18 months after sustaining a distal radius Salter-Harris II fracture. Radiographs show a complete premature closure of the distal radius physis, with continued growth of the distal ulna (ulnar plus variance). What is the most appropriate surgical treatment?

Explanation

For a completely closed distal radius physis with symptomatic ulnar positive variance in a growing child, restoring alignment via distal radius lengthening and preventing further discrepancy by halting distal ulna growth is indicated. Bar excision is ineffective if the physis is completely closed.

Question 64

On an AP pelvis radiograph of a 6-month-old infant evaluated for DDH, the femoral head ossific nucleus is absent. Which of the following describes the normal expected position of the proximal femoral metaphysis?

Explanation

In a normal hip, the proximal medial metaphysis should be situated in the lower inner quadrant. This quadrant is formed by the intersection of Perkin's line (vertical) and Hilgenreiner's line (horizontal).

Question 65

A 9-year-old girl sustains a Delbet Type II (transcervical) femoral neck fracture after falling from a tree. She is treated with urgent open reduction and internal fixation with cannulated screws. Which of the following complications occurs at the highest rate in this specific injury pattern?

Explanation

Pediatric femoral neck fractures carry a high risk of avascular necrosis (AVN). Delbet Type I (transepiphyseal) and Type II (transcervical) have the highest rates of AVN, with Type II occurring at a rate of 30-50%.

Question 66

A 14-year-old boy sustains a twisting injury to his ankle. Radiographs show a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. What is the anatomical rationale for this specific fracture pattern?

Explanation

The distal tibial physis closes in a specific pattern: central, then posteromedial, and finally anterolateral. A juvenile Tillaux fracture occurs when the anterolateral portion is still open and is avulsed by the anterior inferior tibiofibular ligament.

Question 67

A 12-year-old boy with spastic quadriplegic cerebral palsy has a progressive 80-degree neuromuscular scoliosis with marked pelvic obliquity. He is non-ambulatory and has difficulty sitting in his wheelchair. Surgical planning should most likely involve:

Explanation

In non-ambulatory patients with severe neuromuscular scoliosis and significant pelvic obliquity, extending the spinal fusion to the pelvis is crucial. This achieves and maintains a level pelvis, allowing for proper sitting balance.

Question 68

A 6-year-old girl sustains a closed fracture of the distal third of the radius and ulna. Following closed reduction and casting, the radiographs show 15 degrees of apex volar angulation. What is the most appropriate management?

Explanation

In a child under 9 years of age with a distal third both-bone forearm fracture, up to 15-20 degrees of angulation is acceptable. The high remodeling potential near the rapidly growing distal physes makes observation and continuation of casting appropriate.

Question 69

A 15-year-old boy presents with back pain and increased thoracic kyphosis. Standing lateral radiographs reveal a thoracic kyphosis of 65 degrees and anterior wedging of 3 consecutive vertebrae of 6 degrees each. What is the most appropriate initial management?

Explanation

The patient meets the radiographic criteria for Scheuermann's kyphosis (>5 degrees wedging across 3 consecutive vertebrae). For symptomatic curves between 50 and 75 degrees in skeletally immature or recently mature patients, extension bracing and physical therapy is the standard initial treatment.

Question 70

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the mother notes that the child is no longer kicking her leg on the affected side. On examination, the infant has decreased active knee extension but normal ankle movements. What is the most appropriate next step in management?

Explanation

The child has developed a femoral nerve palsy, a known complication of hyperflexion in a Pavlik harness. The harness should be removed or the anterior straps loosened; typically, complete removal and observation is recommended until full neurologic function returns.

Question 71

A 5-year-old boy falls on an outstretched hand and sustains a lateral condyle fracture of the distal humerus. Initial radiographs show 1 mm of displacement, and he is placed in a long arm cast. At 1-week follow-up, radiographs show 3 mm of displacement. What is the most appropriate management?

Explanation

Lateral condyle fractures displaced > 2 mm are at high risk for nonunion and cubitus valgus deformity because the fracture fragment is bathed in synovial fluid and subject to the pull of the extensor origin. ORIF is indicated to ensure precise anatomic reduction of the articular surface.

Question 72

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

Explanation

Bracing is strictly indicated for skeletally immature patients (Risser 0-2, premenarchal) with curves between 25 and 45 degrees. The primary goal of a TLSO brace is to halt curve progression to a surgical magnitude during the rapid adolescent growth spurt.

Question 73

A 6-year-old boy sustains a completely displaced posteromedial supracondylar humerus fracture. On presentation, the hand is pink and warm, but the radial pulse is absent. Capillary refill is 2 seconds. What is the most appropriate initial management?

Explanation

A "pulseless, pink" hand in the setting of a completely displaced supracondylar humerus fracture indicates adequate collateral perfusion. The immediate next step is urgent closed reduction and percutaneous pinning, which often restores the pulse by removing pressure from the brachial artery.

Question 74

An 18-month-old girl is brought to the clinic for a waddling gait. Examination shows restricted hip abduction on the left side and a positive Galeazzi sign. Radiographs confirm a dislocated left hip with a dysplastic acetabulum (acetabular index 38 degrees). What is the most appropriate initial surgical management?

Explanation

In children older than 18 months with a completely dislocated hip, closed reduction is rarely successful and carries a high risk of avascular necrosis. Open reduction combined with a femoral shortening osteotomy (to reduce tension) and a pelvic osteotomy (to address significant dysplasia) is typically required.

Question 75

A 3-year-old boy is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra at T8. Which of the following screening tests must be routinely obtained to evaluate for associated conditions?

Explanation

Congenital scoliosis is highly associated with VACTERL anomalies, including congenital cardiac and renal defects. All patients must be screened with an echocardiogram, a renal ultrasound, and an MRI of the entire neuroaxis to rule out intraspinal anomalies.

Question 76

A 10-year-old boy sustains a Salter-Harris II fracture of the distal femur. It is treated with closed reduction and percutaneous pinning. Which of the following is the most common complication associated with this specific injury?

Explanation

Distal femur physeal fractures have a notoriously high rate of growth arrest (up to 50%). This occurs because the undulating nature of the distal femoral physis leads to severe crushing of the physeal germinal cells during fracture displacement.

Question 77

On an anteroposterior pelvis radiograph of a 6-month-old infant being evaluated for DDH, the proximal femoral ossific nucleus is located in the upper outer quadrant formed by Hilgenreiner's and Perkin's lines. What does this radiographic finding indicate?

Explanation

In a normal hip, the proximal femoral ossific nucleus should be located in the lower inner (inferomedial) quadrant formed by the intersection of Hilgenreiner's (horizontal) and Perkin's (vertical) lines. Location in the upper outer quadrant confirms a lateral and superior dislocation.

Question 78

A 14-year-old boy with spastic quadriplegic cerebral palsy presents with a 75-degree thoracolumbar scoliosis and severe pelvic obliquity. He is non-ambulatory and has lost the ability to sit comfortably in his custom wheelchair. Which of the following surgical strategies is most appropriate?

Explanation

In non-ambulatory patients with severe neuromuscular scoliosis and pelvic obliquity (e.g., severe Cerebral Palsy), the primary goal is to provide a balanced, stable sitting spine. This typically requires a long posterior spinal fusion extending from the upper thoracic spine (T2 or T3) down to the pelvis.

Question 79

A 13-year-old boy complains of ankle pain after a twisting injury. Radiographs show a fracture of the distal tibia that appears as a Salter-Harris III on the AP view and a Salter-Harris II on the lateral view (Triplane fracture). What is the normal closure pattern of the distal tibial physis that predisposes adolescents to this injury?

Explanation

The distal tibial physis closes asymmetrically in a specific pattern: central, anteromedial, posteromedial, and finally anterolateral. This asymmetric closure dictates the fracture pattern seen in transitional injuries like Tillaux and Triplane fractures.

Question 80

During closed reduction and spica casting for a 9-month-old girl with DDH, the hip reduces at 40 degrees of abduction and re-dislocates at 20 degrees of abduction. The safe zone of Ramsey is 20 to 60 degrees. What is the primary risk of immobilizing the hip in excessive abduction (>60 degrees)?

Explanation

Immobilization of a dysplastic hip in extreme abduction (greater than 60 degrees) significantly increases the risk of avascular necrosis (AVN). The extreme position compresses the extracapsular vessels (medial circumflex femoral artery) against the margin of the acetabulum.

Question 81

A 10-month-old infant presents with infantile idiopathic scoliosis measuring 25 degrees. The rib-vertebral angle difference (RVAD) of Mehta is 28 degrees, and phase 2 rib-vertebral overlap is present on the convex side. What is the most likely natural history of this condition without intervention?

Explanation

A Mehta's RVAD greater than 20 degrees and the presence of Phase 2 rib-vertebral overlap (where the rib head overlaps the vertebral body on the convex side) are highly predictive of a progressive, non-resolving curve in infantile idiopathic scoliosis.

Question 82

A 7-year-old girl sustains a both-bone forearm fracture. Closed reduction is performed in the emergency department. Which of the following post-reduction radiographic parameters is considered unacceptable and requires surgical fixation or remanipulation?

Explanation

In pediatric both-bone forearm fractures, maintaining the radial bow is critical for preserving functional forearm pronation and supination. While minor angulation and complete translation can remodel adequately in a 7-year-old, loss of the radial bow will cause a permanent mechanical block to rotation.

Question 83

A 4-week-old boy is fitted with a Pavlik harness for an Ortolani-positive right hip. To ensure proper positioning and minimize neurovascular or ischemic complications, how should the harness straps be adjusted?

Explanation

The Pavlik harness should flex the hips to approximately 90-100 degrees to prevent femoral nerve palsy (caused by hyperflexion). The posterior straps should limit adduction to neutral to prevent redislocation while avoiding forced abduction, which causes avascular necrosis.

Question 84

A 13-year-old female with adolescent idiopathic scoliosis presents for routine evaluation. Radiographs reveal a 22-degree right thoracic curve. Evaluation of the iliac apophysis demonstrates ossification covering the anterior 75% of the iliac crest, but not yet reaching the posterior superior iliac spine (PSIS). What Risser stage does this represent?

Explanation

The Risser classification evaluates skeletal maturity based on the ossification of the iliac apophysis. Risser 3 corresponds to ossification covering 50% to 75% of the iliac crest. Risser 4 covers 75% to 100%, and Risser 5 indicates complete fusion to the ilium.

Question 85

A 4-month-old girl has been treated with a Pavlik harness for 4 weeks for an irreducible developmental dysplasia of the hip (DDH). Repeat ultrasound demonstrates a persistently dislocated left hip without significant improvement in the alpha angle. What is the most appropriate next step in management?

Explanation

Prolonged use of a Pavlik harness in an irreducible hip beyond 3 to 4 weeks can cause 'Pavlik harness disease', damaging the posterior acetabulum. The appropriate next step is a closed reduction and spica casting under anesthesia.

Question 86

A 6-year-old boy presents with a left-sided thoracic curve of 25 degrees. His neurological examination is unremarkable. What is the most appropriate next diagnostic step before considering orthotic management?

Explanation

Juvenile idiopathic scoliosis, particularly in males or when presenting with a left-sided thoracic curve, has a high association with intraspinal anomalies such as a syrinx or tethered cord. An MRI is strongly indicated to rule out these anomalies before initiating bracing or surgery.

Question 87

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

Explanation

In a pulseless, pink hand following adequate reduction and pinning of a supracondylar fracture, the extremity has adequate collateral perfusion. Close clinical observation is recommended as the palpable pulse often returns gradually without surgical exploration.

Question 88

An 18-month-old girl is newly diagnosed with developmental dysplasia of the right hip (DDH). The hip is completely dislocated but reducible on examination. Which of the following is the most appropriate initial treatment?

Explanation

In a child older than 6 months of age who has begun to stand or walk, the Pavlik harness has an unacceptably high failure rate. Closed reduction and spica casting is the preferred initial treatment for typical DDH in children aged 6 to 18 months.

Question 89

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

Explanation

Bracing is definitively indicated in a growing child (Risser 0-2, premenarchal) with an idiopathic curve measuring 25 to 45 degrees. Evidence shows it significantly decreases the likelihood of curve progression to the surgical threshold.

Question 90

A 3-year-old boy sustains a low-energy, isolated spiral fracture of the midshaft femur. Child abuse has been thoroughly ruled out. What is the gold standard of treatment for this injury?

Explanation

Early spica casting is the standard of care for isolated, low-energy diaphyseal femur fractures in children aged 6 months to 5 years. Operative fixation with flexible nails is generally reserved for older children, typically over 5 years of age.

Question 91

Which of the following congenital spinal anomalies has the highest risk of rapid curve progression and requires the earliest surgical intervention?

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra at the same level causes a severe tethering effect on one side with unchecked growth on the opposite side. This has a nearly 100% chance of progression and requires early spinal fusion.

Question 92

A 13-year-old boy sustains an intra-articular fracture of the distal tibia. Radiographs show a fracture line traversing the lateral epiphysis and extending superiorly through the lateral physis. What is the classic mechanism of this specific injury pattern?

Explanation

This describes a juvenile Tillaux fracture, which is an avulsion of the anterolateral distal tibial epiphysis by the anterior inferior tibiofibular ligament (AITFL). The typical mechanism is external rotation of the foot on the tibia.

Question 93

An ultrasound of the hip is performed on a 6-week-old infant suspected of having DDH. Which of the following sonographic measurements is most diagnostic of a dysplastic hip?

Explanation

The alpha angle measures the osseous roof of the acetabulum on coronal ultrasound. An alpha angle of less than 60 degrees indicates inadequate osseous coverage and acetabular dysplasia.

Question 94

A 14-year-old girl with adolescent idiopathic scoliosis presents for follow-up. Standing full-spine radiographs show a right thoracic curve of 55 degrees. She is post-menarchal and Risser 4. What is the most appropriate treatment recommendation?

Explanation

In a skeletally mature or nearly mature adolescent (Risser 4), a thoracic curve of 50 degrees or more is highly likely to continue progressing into adulthood. Surgical correction with posterior spinal fusion is the standard indication.

Question 95

An 8-year-old boy falls and sustains a closed diaphyseal both-bone forearm fracture. What is the maximum acceptable angulation in the middle third of the radius and ulna to allow for a satisfactory functional outcome with non-operative treatment?

Explanation

In children under 10 years old, up to 15 degrees of angulation and complete displacement in the middle third of the forearm are often acceptable due to robust remodeling potential. Beyond 15 degrees, closed reduction or operative fixation is typically required.

Question 96

An infant is born with bilateral dislocated hips and severe contractures of multiple joints consistent with arthrogryposis multiplex congenita. What is the expected outcome regarding the management of these teratologic hip dislocations?

Explanation

Teratologic hip dislocations, such as those associated with arthrogryposis or spina bifida, are inherently rigid and typically fail conservative orthotic treatment. They almost universally require open reduction to achieve stable relocation.

Question 97

A 14-year-old non-ambulatory boy with Duchenne muscular dystrophy develops a progressive neuromuscular scoliosis of 45 degrees. Which of the following is an established principle regarding surgical treatment for this patient?

Explanation

In non-ambulatory patients with Duchenne muscular dystrophy, spinal fusion is usually indicated for curves >20-30 degrees and should extend to the pelvis to correct pelvic obliquity and maintain a stable sitting posture. Pulmonary function decline is slowed, but rarely improves.

Question 98

A 12-year-old boy presents with an acute ankle injury. Radiographs reveal a distal tibia fracture that appears as a Salter-Harris III injury on the AP view and a Salter-Harris II injury on the lateral view. What is the most appropriate anatomical classification of this fracture?

Explanation

A triplane fracture is a transitional fracture of the distal tibia occurring in three planes. It is anatomically a Salter-Harris IV equivalent but classically presents with the appearance of a Salter-Harris III on the AP radiograph and a Salter-Harris II on the lateral radiograph.

Question 99

During the application of a spica cast for DDH, the hip is forcefully placed in a position of extreme abduction (the "frog-leg" position). What is the most devastating complication associated with this specific positioning?

Explanation

Forced abduction in a spica cast dramatically increases intracapsular pressure and mechanical compression on the extraosseous epiphyseal vessels. This "frog-leg" position is the primary risk factor for iatrogenic avascular necrosis (AVN) in DDH treatment.

Question 100

A 5-year-old child sustains a widely displaced (3 mm) lateral condyle fracture of the humerus. If left untreated and a nonunion develops, which of the following complications is most likely to present years later?

Explanation

Untreated displaced lateral condyle fractures have a high rate of nonunion, which frequently leads to a progressive cubitus valgus deformity. The resulting valgus stretch over time can stretch the ulnar nerve, producing a classic tardy ulnar nerve palsy.

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

Pediatric Orthopedic MCQs (Set 3): Fractures, DDH & Scoliosis | AAOS & ABOS Review

Key Takeaway

Pediatric Orthopedic MCQs (Set 3): Fractures, DDH & Scoliosis | AAOS & ABOS Review

Chapter Index