AAOS Pediatric Orthopedic MCQs: Scoliosis & Fractures

Question 1

A 10-year-old boy with an L1 myelomeningocele has a low-grade fever and a swollen thigh that is warm to touch and erythematous. AP and lateral radiographs are shown in Figures 24a and 24b. Management should consist of

Explanation

Fractures of the long bones are common in patients with myelodysplasia, and the frequency of fracture increases with higher level defects. Fractures also occur following surgery and immobilization secondary to disuse osteoporosis. The response to the fracture (swelling, fever, warmth, erythema) is often confused with infection, osteomyelitis, or cellulitis. Management should consist of a short period of immobilization in a well-padded splint. Long-term casting results in further osteopenia and repeated fractures. Lock TR, Aronson DD: Fractures in patients who have myelomeningocele. J Bone Joint Surg Am 1989;71:1153-1157.

Question 2

A 6-year-old African-American boy with sickle cell disease has had pain and limited use of his right arm for the past 3 days. History reveals that he sustained a humeral fracture approximately 3 years ago. A lateral radiograph is shown in Figure 25. Based on these findings, a presumptive diagnosis of chronic osteomyelitis is made. What are the two most likely organisms?

Pediatrics 2004 Practice Questions: Set 3 (Solved) - Figure 3

Explanation

The risk of Salmonella osteomyelitis is much greater in patients with sickle cell disease than the general population. The exact reason for this increased risk is still unclear, but it appears to be associated with an increased incidence of gastrointestinal microinfarcts and abscesses. Both Staphylococcus aureus and Salmonella have been mentioned as the most prevalent causative organisms. Piehl FC, David RJ, Prugh SI: Osteomyelitis in sickle cell disease. J Pediatr Orthop 1993;13:225-227. Givner LB, Luddy RE, Schwartz AD: Etiology of osteomyelitis in patients with major sickle hemoglobinopathies. J Pediatr 1981;99:411-413. Epps CH Jr, Bryant DD III, Coles MJ, Castro O: Osteomyelitis in patients who have sickle-cell disease: Diagnosis and management. J Bone Joint Surg Am 1991;73:1281-1294.

Question 3

A 7-year-old child is unresponsive, tachycardic, and has a systolic blood pressure of 50 mm Hg after being struck by a car. The patient is intubated and venous access is obtained. The secondary survey reveals an unstable pelvis. Despite adequate resuscitation, the patient continues to be hemodynamically unstable. What is the best course of action?

Explanation

The patient is hemodynamically unstable, so any treatment should be aimed at stabilization. Airway, breathing, and circulation are the most important areas to control initially; the patient has been intubated and has adequate venous access. Despite fluid resuscitation, the child remains hypotensive, indicating continued blood loss. With an unstable pelvic fracture there can be significant hemorrhage. Decreasing the pelvic volume can decrease blood loss related to the pelvic fracture. This can be done in the emergency department by applying a pelvic sling. Other means of decreasing pelvic volume include a pelvic clamp, a simple anterior frame pelvic external fixator, or a simple sheet tied around the pelvis. These maneuvers may stabilize the patient so that further evaluation and treatment can be undertaken. All of the other choices will delay stabilization and should be postponed until the patient is stabilized. Torode I, Zieg D: Pelvic fractures in children. J Pediatr Orthop 1985;5:76-84. Eichelberger MR, Randolph JG: Pediatric trauma-initial resuscitation, in Moore EE, Eisman B, Van Way CE (eds): Critical Decisions in Trauma. St Louis, MO, CV Mosby, 1984, p 344.

Question 4

A 3-year-old boy with severe cerebral palsy is unable to sit independently and does not crawl. Examination reveals a 40-degree hip flexion contracture by the Thomas test and 25 degrees of passive abduction. A radiograph of the pelvis shows subluxation of both hips, with a migration index of 30%. Management should consist of

Explanation

Progressive hip subluxation occurs in up to 50% of children with spastic quadriparesis. The subluxation is the result of chronic muscle hypertonicity, especially in the adductor muscle group. In time, the constant muscle tension will lead to dislocation, dysplastic changes in the acetabulum, and erosive changes in the cartilage of the femoral head. Many of these children will experience pain. Two recent studies have shown that early soft-tissue releases can successfully prevent progressive subluxation in children who are younger than age 4 years and who have a Reimers index (migration index) of less than 40%. Botulinum toxin A injections may reduce tone in the adductors for 4 to 6 months, but it is difficult to inject into the iliopsoas. Additionally, there are no long-term studies documenting the efficacy of botulinum toxin A to treat progressive hip subluxation in patients who have spastic quadriparesis. In general, proximal femoral osteotomy, combined with soft-tissue release as necessary, is indicated in older children (older than age 4 years) with progressive subluxation. Although selective dorsal rhizotomy has been used in nonambulatory patients, outcomes are less well documented than in ambulatory patients. There are no studies documenting the effect of selective dorsal rhizotomy on progressive hip subluxation in nonambulatory children. Miller F, Cardoso Dias R, Dabney KW, et al: Soft-tissue release for spastic hip subluxation in cerebral palsy. J Pediatr Orthop 1997;17:571-584.

Question 5

The parents of a 3-year-old girl who has had pain and swelling in the right ankle for the past 3 months now report that she has a limp and that the right knee and both ankles are painful and swollen. The limp and difficulty walking are most severe in the morning when the child first gets out of bed and are also more severe after extended walking. The parents deny fever, chills, weight loss, or night pain. Examination shows mild swelling and slightly restricted motion of the right knee and both ankles but is otherwise normal. In addition to initiation of treatment, the child should be referred to which of the following specialists?

Explanation

Pauciarticular juvenile rheumatoid arthritis (JRA) is the most common subgroup of JRA. It typically presents between the ages of 2 to 4 years with a mild swelling of one to four joints. Girls are affected four times more often than boys. The ankle and knee are commonly involved, and limping is typically worse in the morning and after extended activity. The diagnosis of pauciarticular JRA is typically one of exclusion because laboratory studies, including erythrocyte sedimentation rate and rheumatoid factor, are usually within normal limits. Pauciarticular JRA has the highest incidence of chronic uveitis, and in the subgroup with elevated antinuclear antibody (ANA) titers, the incidence is 75%. In JRA, uveitis usually occurs after the onset of synovitis but may precede the joint symptoms. At the early stage of uveitis, the patient is asymptomatic. If the eye condition is not detected and treated, progressive loss of vision may occur. Orthopaedic surgeons may be instrumental in making the diagnosis of pauciarticular JRA. Pauciarticular JRA is not associated with conditions that require input from the other specialists. Carey TP: Inflammatory arthritides: Juvenile rheumatoid arthritis, seronegative spondyloarthropathies, transient synovitis, hemophilic arthropathy, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1315-1321.

Question 6

A 9-year-old boy has pain over the midfoot medially with activity. Based on the findings shown in Figures 26a and 26b, which of the following is considered the most effective short-term management?

Explanation

While Kohler's disease has a benign course, temporary cast immobilization has been shown to result in a shortened duration of symptoms. Core decompression or other surgery is not warranted because of the benign nature. Shoe inserts may be beneficial, but there are no studies to support their use. Borges JL, Guile JT, Bowen JR: Kohler's bone disease of the tarsal navicular. J Pediatr Orthop 1995;15:596-598.

Question 7

During the first 2 years of life, which of the following actions is most responsible for increasing structural stability of the physis?

Explanation

The zone of Ranvier provides the earliest increase in strength of the physis. During the first year of life, the zone spreads over the adjacent metaphysis to form a fibrous circumferential ring bridging from the epiphysis to the diaphysis. This ring increases the mechanical strength of the physis. The zone also helps the physis grow latitudinally. In turn, the increased width of the physis helps the physis further resist mechanical forces. The change in shape of the physis to its progressively more undulating form is also a factor in increasing physeal strength, but this occurs over a longer period of time, as the child's activity level increases. The undulations of the physis seen in some growth plates also add to stability but to a lesser extent. The other changes contribute little toward increasing physeal strength. Burkus J, Ogden J: Development of the distal femoral epiphysis: A microscopic morphological investigation of the zone of Ranvier. J Pediatr Orthop 1984;4:661-668.

Question 8

Because the patient shown in Figure 27 can no longer fit in shoes, treatment of the deformity should consist of

Pediatrics 2004 Practice Questions: Set 3 (Solved) - Figure 6

Explanation

In local gigantism, a ray resection allows proper fitting of shoes. The ray resection narrows the foot and shortens the length. The foot may require further surgery with growth. Debulking, physeal arrest, and distal phalanx amputation are unlikely to be effective. Turra S, Santini S, Cagnoni G, Jacopetti T: Gigantism of the foot: Our experience in seven cases. J Pediatr Orthop 1998;18:337-345.

Question 9

Examination of a 9-year-old girl who injured her left elbow in a fall reveals tenderness and swelling localized to the medial aspect of the elbow. Motor and sensory examinations of the hand are normal, and circulation is intact. A radiograph is seen in Figure 28. Management should consist of

Pediatrics 2004 Practice Questions: Set 3 (Solved) - Figure 7

Explanation

Avulsion fractures of the medial epicondyle are caused by a valgus stress applied to the immature elbow and usually occur in children between the ages of 9 and 14 years. Long-term studies have shown that isolated fractures of the medial epicondyle with between 5 to 15 mm of displacement heal well. Brief immobilization (1 to 2 weeks) in a long arm cast or splint yields results similar to open reduction and internal fixation. Fibrous union of the fragment is not associated with significant symptoms or diminished function. Surgical excision of the fragment yielded the worst results in one study and should be avoided. Open reduction is best reserved for those injuries in which the medial epicondylar fragment becomes entrapped in the elbow joint during reduction and cannot be extracted by closed manipulation. Farsetti P, Potenza V, Caterini R, Ippolito E: Long-term results of treatment of fractures of the medial humeral epicondyle in children. J Bone Joint Surg Am 2001;83:1299-1305.

Question 10

A 2-year-old child has refused to bear weight on his leg for the past 2 days. His parents report that he will crawl, has no fever, and has painless full range of motion of his hip and knee. Examination reveals no deformity or bruising, but there is mild swelling and tenderness over the anterior tibia. C-reactive protein, WBC count, and erythrocyte sedimentation rate studies are normal. Radiographs are negative. What is the best course of action?

Explanation

Despite the negative radiographic findings, the child's age and presentation are most consistent with a toddler's fracture. There is often not a witnessed injury. The differential diagnosis of infection is unlikely given that the child is afebrile and shows no signs of illness. Immobilization will make the child more comfortable and will often allow weight bearing. Repeat radiographs at the end of treatment will show a healing fracture and confirm the diagnosis. Aspiration of the tibial metaphysis would be indicated to obtain material for culture. The bone scan and MRI would show abnormalities, but these studies are nonspecific, costly, and time-consuming. Occasionally, oblique radiographs will show the fracture. Halsey MF, Finzel KC, Carrion WV, Haralabatos SS, et al: Toddler's fracture: Presumptive diagnosis and treatment. J Pediatr Orthop 2001;21:152-156.

Question 11

A 7-year-old girl sustains the fracture shown in Figure 29a. Casting results in uneventful healing. Ten months later, the patient has a progressive valgus deformity of the right lower extremity. A radiograph is shown in Figure 29b. Management should now consist of

Explanation

Although fractures of the proximal tibial metaphysis in young children appear innocuous, development of a progressive valgus deformity is possible despite adequate and appropriate treatment. When treating a child with this injury, it is prudent to warn the parents that a valgus deformity of the tibia may develop. The most likely cause is asymmetric growth of the proximal tibial physis. Because spontaneous angular improvement can be expected in most patients, surgery to correct these deformities should be delayed at least 2 to 3 years and should be limited to patients who have symptoms. There are no studies that document the efficacy of bracing for this deformity. Tuten HR, Keeler KA, Gabos PG, et al: Posttraumatic tibia valga in children: A long-term follow-up note. J Bone Joint Surg Am 1999;81:799-810.

Question 12

An obese 10-year-old boy has had left groin pain and a limp for the past 2 months. Examination reveals decreased abduction and internal rotation. Laboratory studies show normal renal function and an elevated thyroid-stimulating hormone (TSH) level. AP and frog lateral radiographs of the pelvis are shown in Figures 30a and 30b. What is the best course of action?

Explanation

The radiographs show a grade I slipped capital femoral epiphysis (SCFE) that is classified as stable because the child is able to bear weight. The elevated TSH level indicates possible hypothyroidism. SCFE usually occurs in boys age 12 to 14 years. Because of the patient's young age and hypothyroidism, he is at increased risk for slippage of the contralateral hip; therefore, prophylactic pinning of the uninvolved side also should be considered. Because of the risk of slip progression, crutch treatment and nonsteroidal anti-inflammatory drugs are not indicated. Realignment osteotomy is not indicated for grade I SCFE. Traction to reduce the slip, followed by pinning, has been advocated for unstable slips but is not indicated here. Loder RT, Wittenberg B, DeSilva G: Slipped capital femoral epiphysis associated with endocrine disorders. J Pediatr Orthop 1995;15:349-356.

Question 13

A 7-year-old boy has had chronic left leg pain that is worse at night but is not activity related. Use of nonsteroidal anti-inflammatory drugs for the past 6 months has failed to provide relief. A CBC count with differential, erythrocyte sedimentation rate, and C-reactive protein are within normal limits. Radiographs and a CT scan are shown in Figures 31a through 31c. Management should consist of

Explanation

Osteoid osteomas are painful bone lesions, with radiographs revealing a dense sclerotic cortex surrounding a small radiolucency or nidus. Symptoms often are worse at night but usually are not activity related. While treatment in the past has consisted of open en bloc excision, current means of removal include percutaneous drilling under CT guidance and percutaneous radiofrequency coagulation. Success rates of percutaneous treatment are comparable to those seen following open procedures. The characteristic radiographic appearance of this lesion usually obviates the need for biopsy. Because the lesion is not caused by pyogenic organisms, antibiotics are not indicated. Donahue F, Ahmad A, Mnaymneh W, Pevsner NH: Osteoid osteoma: Computed tomography guided percutaneous excision. Clin Orthop 1999;366:191-196.

Question 14

In patients with neurofibromatosis, what is the most important sign of impending rapid progression of a spinal deformity?

Explanation

Neurofibromatosis can progress very rapidly. Rib penciling is the only singular prognostic factor. Significant progression has been observed in 87% of the curves with three or more penciled ribs. The other factors are often present but do not have a high correlation with rapid, severe progression. Crawford AH, Schorry EK: Neurofibromatosis in children: The role of the orthopaedist. J Am Acad Orthop Surg 1999;7:217-230.

Question 15

The fracture shown in Figure 32 is strongly indicative of what diagnosis?

Pediatrics 2004 Practice Questions: Set 3 (Solved) - Figure 15

Explanation

Fractures that occur through the primary spongiosa at the subphyseal region of the metaphysis are highly specific for child abuse. On radiographic studies, the metaphyseal lucency in these injuries may appear as either the so-called "bucket-handle" or "metaphyseal corner" fracture. These fractures are not typical features of osteogenesis imperfecta or vitamin D-resistant rickets. The ingestion of lead may lead to thick, transverse bands of increased density at the distal metaphysis. Fractures in the subphyseal region of the metaphysis are not typically seen in children who have osteomyelitis. Kocher MS, Kasser JR: Orthopaedic aspects of child abuse. J Am Acad Orthop Surg 2000;8:10-20.

Question 16

Figures 33a and 33b show the radiographs of a 10-year-old girl who reports a 4-month history of medial foot pain after she was kicked while playing soccer. The pain is worse with activity and partially relieved by rest. Examination reveals tenderness directly over a prominent navicular tuberosity. Management should consist of

Explanation

An accessory tarsal navicular is located at the medial tuberosity of the navicular bone. Nearly all children and adolescents who have a symptomatic accessory tarsal navicular bone become asymptomatic when they reach skeletal maturity. Initial management should include activity restrictions, shoe modification to avoid pressure over the prominent navicular, and non-narcotic analgesics. Although anecdotal, the use of arch supports may be helpful. When pain is refractory to these methods, a short period of cast immobilization may be useful. Surgery should be reserved for patients who have disabling symptoms despite a prolonged period of nonsurgical management. When surgery is indicated, simple excision of the accessory navicular is recommended. Sella EJ, Lawson JP, Ogden JA: The accessory navicular synchondrosis. Clin Orthop 1986;209:280-285.

Question 17

An 18-month-old child with obstetrical palsy has a maximum external rotation as shown in Figure 34. The parents should be advised that without surgical treatment the likelihood that glenoid dysplasia will develop is approximately what percent?

Pediatrics 2004 Practice Questions: Set 3 (Solved) - Figure 18

Explanation

Based on the available literature, the probability of development of glenoid dysplasia in the setting of a significant limitation of external rotation is close to 70%. Humeral dysplasia is also likely and can be managed surgically. Efforts are being made to identify procedures that will prevent glenoid dysplasia and help maintain function. Pearl ML, Edgerton BW: Glenoid deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am 1998;80:659-667. Waters PM, Smith GR, Jaramillo D: Glenohumeral deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am 1998;80:668-677.

Question 18

A 10-year-old boy has a painful, swollen knee after falling off his bicycle. Examination reveals no other injuries. Radiographs are shown in Figures 35a and 35b. Initial management of this fracture should consist of

Explanation

The radiographs show a minimally displaced fracture of the tibial eminence, which is classified as a McKeever type II injury. In a number of studies, it has been found that most of these fractures will reduce with extension of the knee. This is often made easier with evacuation of the hemarthrosis. The position of knee immobilization is controversial, with some authors preferring full extension and others preferring 20 degrees of flexion. Flexion to 90 degrees will further displace the fragment. If the fragment does not reduce or if the patient has a McKeever type III or IV injury, reduction and internal fixation are required. This can be done with either an open or an arthroscopic procedure. Excision of the fragment is not indicated. Meyers MH, McKeever FM: Fractures of the intercondylar eminence of the tibia. J Bone Joint Surg Am 1970;52:1677-1684. Wiley JJ, Baxter MP: Tibial spine fractures in children. Clin Orthop 1990;255:54-60 Janarv PM, Westblad P, Johansson C, Hirsch G: Long-term follow-up of anterior tibial spine fractures in children. J Pediatr Orthop 1995;15:63-68.

Question 19

Figures 36a and 36b show the radiographs of a 3-year old child who has a congenital upper extremity deformity. Which of the following features would be a major contraindication to a centralization procedure?

Explanation

The patient has bilateral absent radii or radial clubhand. Patients who lack elbow flexion take advantage of the hand position to reach their mouths, and a centralization procedure would take away that ability. This procedure can be performed on patients with partial to complete absence of the radius. A hypoplastic thumb can be addressed at a staged procedure; it does not represent a contraindication to centralization. Complete thumb absence can be addressed by pollicizing the index ray. Green DP: Operative Hand Surgery, ed 2. New York, NY, Churchill Livingstone, 1988, pp 269-271.

Question 20

Examination of a 4-year old child with obstetrical palsy reveals weak deltoids, pectoralis major strength of 4-5, and normal hand function. External rotation of the shoulder is limited. What is the most appropriate surgical procedure to restore external rotation?

Explanation

Transfer of the latissimus dorsi and teres major to the posterior rotator cuff will restore external rotation and some abduction. The procedure should be performed in children who are approximately age 4 years, following spontaneous recovery and prior to significant stiffness. External rotation osteotomy is more appropriate for an older child. Fusion should not be performed until skeletal maturity. Distal biceps rerouting restores pronation for a supination deformity. Latissimus dorsi and teres major transfer to the subscapularis would accentuate the internal rotation. In younger patients without significant bony deformity, a subscapularis slide or lengthening can restore external rotation. Strecker WB, McAllister JW, Manske PR, Schoenecker PL, Dailey LA: Sever-L'Episcopo transfers in obstetrical palsy: A retrospective review of twenty cases. J Pediatr Orthop 1990;10:442-444.

Question 21

A 7-month-old girl has had a severe flatfoot deformity since birth. The talar head is prominent in the medial plantar arch of the foot. No other deformities of the spine or extremities are present. Motor and sensory examinations of the extremities are normal. Figures 37a through 37c show simulated weight-bearing AP and lateral radiographs and a planter flexion lateral view. What is the most likely diagnosis?

Explanation

Congenital vertical talus is a fixed dorsal dislocation of the talonavicular joint with equinus of the ankle joint. The AP radiograph shows valgus of the midfoot and an increased talocalcaneal angle; the lateral radiograph shows a vertically positioned talus and equinus of the ankle joint, and the plantar flexion lateral view shows that the talonavicular joint does not reduce. A line drawn through the long axis of the talus passes below the long axis of the first metatarsal. Initial management should consist of serial casting to stretch the dorsal soft-tissue structures; surgery eventually will be required to reduce the talonavicular joint. The differential diagnosis of congenital vertical talus includes pes calcaneovalgus, flexible pes planus, and peroneal spastic flatfoot. Pes calcaneovalgus, flexible pes planus, congenital short Achilles tendon, and peroneal spastic flatfoot would not show resistent dorsal dislocation of the navicular on the plantar flexion view. Kodros SA, Dias LS: Single-stage surgical correction of congenital vertical talus. J Pediatr Orthop 1999;19:42-48.

Question 22

A 12-year-old boy has severe left shoulder pain after being struck by an automobile. A chest radiograph, AP and lateral radiographs, and a CT scan with three-dimensional reconstruction of the scapula are shown in Figures 38a through 38d. Management should consist of

Explanation

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

Question 23

Figure 39 shows the radiograph of a 4-month old infant who has been undergoing weekly casting since birth for a congenital equinovarus deformity. Management should now consist of

Pediatrics 2004 Practice Questions: Set 3 (Solved) - Figure 30

Explanation

The radiograph shows the development of a rocker-bottom foot deformity. A rocker-bottom foot occurs in the treatment of clubfoot when casting is continued in the presence of a very tight gastrocnemius-soleus complex and an uncorrected hindfoot. While there are some preliminary reports on using Botox injection and continued casting for the equinus deformity, most authors recommend posterior or posterior medial release. Percutaneous tenotomy has been recently recommended with the resurgence of the Ponsetti technique. Lehman WB, Atar D: Complications in the management of talipes equinovarus, in Drennan JC (ed): The Child's Foot and Ankle. New York, NY, Raven Press, 1992, pp 135-136. Herring JA: Tachdjian's Pediatric Orthopedics, ed 4. Philadelphia, PA, WB Saunders, 2002, pp 927-935.

Question 24

A 1-year-old infant has the hand deformities shown in Figure 40. What pathologic process is the most likely cause of these deformities?

Pediatrics 2004 Practice Questions: Set 3 (Solved) - Figure 31

Explanation

Streeter's dysplasia is clearly related to rupture of the amnion in utero and is now most commonly referred to as premature amnion rupture sequence. The deformities arise from amniotic bands that wrap about protruding parts and from uterine packing because of the accompanying oligohydramnios. Clubfoot can develop as a result of the latter mechanism. Three limb involvement is most commonly seen, along with syndactyly. Treatment involves resection of bands and Z-plasty of skin. The disease is not genetic and has not been related to teratogen exposure or to iatrogenic influences such as amniocentesis. Developmental field disruption is not seen in this disease, and the growth potential of the involved parts is normal unless neurovascular disruption has arisen from band formation.

Question 25

A 13-year-old girl with hallux valgus reports pain after playing basketball. Radiographs show a hallux valgus angle of 20 degrees, an intermetatarsal angle of 11 degrees, a distal metatarsal articular angle of 10 degrees, and a congruent joint. Management should consist of

Explanation

Shoe wear modification is the most appropriate management based on the patient's age, high activity level, and relatively minor symptoms. She also has a mild hallux valgus. Normal radiographic measurements are an intermetatarsal angle of less than 9 degrees, a hallux valgus angle of less than 15 degrees, and a distal metatarsal articular angle of less than 9 degrees. Surgical procedures should be reserved for patients with more severe or progressive deformities. Stephens HM: Bunions, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1510-1519.

Question 26

A 9-month-old boy is being evaluated for progressive infantile idiopathic scoliosis. Radiographs demonstrate a left thoracic curve of 35 degrees and a rib-vertebra angle difference (RVAD) of 25 degrees. What is the most appropriate initial management?

Explanation

An RVAD greater than 20 degrees in infantile idiopathic scoliosis indicates a high risk of progression. Serial EDF (Mehta) casting is the gold standard for progressive infantile curves to harness remaining growth and potentially achieve a cure.

Question 27

A 6-week-old infant with developmental dysplasia of the hip (DDH) is placed in a Pavlik harness. Two weeks later, the parents report that the infant is no longer actively kicking the right leg. On examination, the knee lacks active extension. Which of the following is the most likely cause of this complication?

Explanation

Excessive flexion in the anterior straps of a Pavlik harness (typically >120 degrees) can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy. The harness should be temporarily discontinued or adjusted.

Question 28

A 5-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. Upon presentation, his hand is pink and well-perfused, but the radial pulse is absent. Following closed reduction and percutaneous pinning, the fracture is perfectly aligned, but the radial pulse remains absent while the hand remains pink. What is the most appropriate next step in management?

Explanation

In a 'pulseless, pink' hand following adequate reduction and stabilization of a supracondylar humerus fracture, observation is appropriate. Collateral circulation provides adequate perfusion, and the brachial artery spasm usually resolves over 24-48 hours.

Question 29

A 3-year-old girl is diagnosed with congenital scoliosis. Which of the following vertebral anomalies carries the highest risk for rapid curve progression and typically requires early surgical intervention?

Explanation

A unilateral unsegmented bar with a contralateral fully segmented hemivertebra provides the most severe growth imbalance. This pattern progresses rapidly and predictably, often necessitating early in situ fusion to prevent severe deformity.

Question 30

A 2-year-old girl presents with a limp. Radiographs reveal a previously undiagnosed left-sided developmental dysplasia of the hip (DDH) with complete dislocation. What is the most appropriate definitive management?

Explanation

In a child over 18-24 months of age with a completely dislocated hip, closed reduction is rarely successful or stable. Open reduction combined with a pelvic osteotomy (and sometimes a femoral shortening osteotomy) is indicated to address secondary acetabular dysplasia.

Question 31

A 4-year-old boy falls off monkey bars and sustains a displaced lateral condyle fracture of the humerus. Which of the following complications is most specifically associated with a failure of this fracture to unite?

Explanation

Lateral condyle fractures are intra-articular and prone to nonunion because the fracture site is bathed in synovial fluid. Nonunion leads to a progressive cubitus valgus deformity, which can stretch the ulnar nerve and cause tardy ulnar nerve palsy years later.

Question 32

A 12-year-old girl presents with adolescent idiopathic scoliosis. She is pre-menarchal. Her Risser sign is 1. Radiographs show a right thoracic curve of 34 degrees. What is the most widely accepted standard of care?

Explanation

Bracing (typically full-time TLSO) is indicated for skeletally immature patients (Risser 0-2) with curves between 25 and 45 degrees. The goal of bracing is to halt progression, not to correct the curve.

Question 33

During open reduction for developmental dysplasia of the hip (DDH) through an anterior approach, several anatomic structures can block concentric reduction. Which structure typically causes the 'hourglass' constriction of the joint capsule?

Explanation

The iliopsoas tendon crosses the anterior capsule and compresses it, creating an 'hourglass' shape that acts as a primary extra-articular block to reduction. This tendon must be released during an anterior open reduction.

Question 34

A 3-year-old boy sustains an isolated, closed, length-stable diaphyseal femur fracture after a low-energy fall. He has no other injuries. What is the preferred treatment?

Explanation

For children 6 months to 5 years of age with closed, isolated, length-stable femur fractures (<2-3 cm of shortening), early spica casting is the gold standard treatment with excellent clinical outcomes.

Question 35

A 14-year-old boy with Duchenne muscular dystrophy develops a progressive 60-degree thoracolumbar scoliosis with significant pelvic obliquity. What is the most appropriate surgical approach?

Explanation

In patients with Duchenne muscular dystrophy and significant scoliosis, the curve tends to progress rapidly and impairs sitting balance. Posterior spinal fusion to the pelvis is necessary to correct pelvic obliquity and provide a stable sitting platform.

Question 36

When interpreting an infant hip ultrasound for DDH using the Graf method, the alpha angle is measured. What does the alpha angle specifically quantify?

Explanation

The alpha angle in the Graf classification measures the bony roof of the acetabulum. An alpha angle greater than or equal to 60 degrees is considered normal (Type I).

Question 37

A 13-year-old girl presents with ankle pain after twisting her leg. Radiographs reveal a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis (Tillaux fracture). What is the pathomechanics of this injury?

Explanation

A juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis caused by tension on the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury. It occurs in adolescents because the medial physis closes before the lateral physis.

Question 38

A 13-year-old boy with adolescent idiopathic scoliosis presents with an atypical curve pattern (a sharp left-sided thoracic curve). He also reports mild headaches. Which of the following is the most appropriate next step in evaluating this patient?

Explanation

Atypical curve patterns, such as a left thoracic curve in AIS, are considered 'red flags' for underlying intraspinal pathology (e.g., syringomyelia, Chiari malformation, tethered cord). An MRI of the entire neuraxis is mandatory to rule out these anomalies.

Question 39

Which of the following positions during spica casting for DDH places the infant at the highest risk for developing avascular necrosis of the femoral head?

Explanation

Extreme abduction (the 'frog-leg' position) in a spica cast dramatically increases the pressure on the medial circumflex femoral artery, leading to a high rate of avascular necrosis. The safe zone requires moderating abduction to 40-50 degrees.

Question 40

An 8-year-old boy sustains a supracondylar fracture of the humerus. Six months later, he demonstrates a prominent cubitus varus deformity. What is the primary underlying cause of this malalignment?

Explanation

Cubitus varus following a supracondylar fracture is primarily a cosmetic deformity resulting from malunion. It is typically caused by failure to correct coronal plane rotation or collapse of a comminuted medial column during initial fixation.

Question 41

A 7-year-old girl with a progressive 55-degree congenital scoliosis undergoes a posterior-only spinal fusion without instrumentation. Three years later, her curve has worsened significantly. What is the phenomenon responsible for this progression?

Explanation

The crankshaft phenomenon occurs in skeletally immature patients (open triradiate cartilage) who undergo posterior-only spinal fusion. Continued anterior growth of the vertebral bodies causes the spine to rotate and curve around the posterior fusion mass.

Question 42

Which of the following is the most pathognomonic radiographic sign of non-accidental trauma (child abuse) in an infant?

Explanation

The classic metaphyseal lesion (CML), also known as a corner fracture or bucket-handle fracture, is highly specific for non-accidental trauma. It results from violent pulling or twisting of an infant's extremity.

Question 43

A 14-year-old boy sustains a triplane fracture of the distal tibia. Radiographically, the fracture appears as a Salter-Harris type III fracture on the anteroposterior (AP) view. What does it resemble on the lateral view?

Explanation

A triplane fracture is a transitional fracture that acts as a Salter-Harris IV equivalent in 3D. Radiographically, it appears as a Salter-Harris III on the AP view and a Salter-Harris II on the lateral view.

Question 44

During a Pemberton pericapsular osteotomy for DDH, the osteotomy cut is directed toward and hinges on which of the following structures?

Explanation

The Pemberton osteotomy is an incomplete pericapsular pelvic osteotomy that hinges on the flexible triradiate cartilage. It relies on the plasticity of this cartilage to allow the acetabular roof to be rotated downward, thus improving coverage and decreasing acetabular volume.

Question 45

An 8-year-old boy falls on an outstretched hand and sustains an isolated plastic deformation of the ulna. On careful examination, he is unable to supinate his forearm and has pain at the elbow. What must be ruled out radiographically?

Explanation

Plastic deformation of the ulna can act similarly to a true ulnar fracture in a Monteggia lesion. It forces a change in forearm length, frequently resulting in a concomitant radial head dislocation that must be identified and reduced.

Question 46

A 2-month-old infant is diagnosed with developmental dysplasia of the hip (DDH). In which of the following scenarios is the use of a Pavlik harness absolutely contraindicated?

Explanation

The Pavlik harness relies on active infant motion to achieve and maintain reduction. It is contraindicated in teratologic dislocations, such as those associated with arthrogryposis or spina bifida, where muscle imbalance and stiffness prevent successful reduction.

Question 47

A 13-year-old girl with adolescent idiopathic scoliosis (AIS) presents for evaluation. Her menarche was 6 months ago. Radiographs reveal a right thoracic curve of 35 degrees and a Risser stage of 0. What is the most appropriate management?

Explanation

Full-time bracing is indicated for skeletally immature patients (Risser 0-2) with progressive curves between 25 and 45 degrees. At 35 degrees with significant remaining growth potential, a TLSO is the standard of care to prevent curve progression.

Question 48

A 5-year-old boy sustains a severe extension-type supracondylar humerus fracture. On presentation, his hand is warm and pink, but the radial pulse is not palpable. After closed reduction and percutaneous pinning, the hand remains well-perfused with an oxygen saturation of 99%, but the pulse remains non-palpable. What is the next best step in management?

Explanation

A pulseless but well-perfused (pink) hand after reduction and pinning of a supracondylar fracture should be closely observed. Collateral circulation is typically adequate, and the pulse often returns over time; surgical exploration is reserved for a pulseless, pale, and poorly perfused hand.

Question 49

A 12-year-old non-ambulatory boy with Duchenne muscular dystrophy presents with a progressive neuromuscular scoliosis of 35 degrees. His forced vital capacity (FVC) is currently 45% of predicted. What is the most appropriate recommendation regarding his spinal deformity?

Explanation

In Duchenne muscular dystrophy, spinal fusion is typically recommended when curves reach 20 to 30 degrees in non-ambulatory patients, provided their FVC is greater than 35%. Bracing is ineffective and poorly tolerated in these patients.

Question 50

A 14-year-old boy sustains a juvenile Tillaux fracture of the ankle.

What is the characteristic mechanism of injury for this fracture pattern?

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. It is caused by an external rotation force that avulses the bony fragment via the anterior inferior tibiofibular ligament as the medial physis has already fused.

Question 51

A 13-year-old girl sustains a twisting injury to her ankle. Radiographs reveal a triplane fracture. Which of the following best describes the typical Salter-Harris classification appearances on orthogonal radiographs?

Explanation

A classic triplane fracture is a Salter-Harris IV equivalent but appears as a Salter-Harris III fracture on the anteroposterior (AP) radiograph and a Salter-Harris II fracture on the lateral radiograph. It typically occurs during the transitional period of physeal closure.

Question 52

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip. At the 2-week follow-up, the parents report that the child has stopped extending the knee on the treated side. What is the most likely cause of this complication?

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, caused by excessive hip flexion that compresses the nerve. It presents as decreased active quadriceps function (lack of knee extension) and resolves with temporary loosening or discontinuation of the flexion straps.

Question 53

A 6-year-old boy falls from the monkey bars and sustains a lateral condyle fracture of the distal humerus. Radiographs show a Milch Type II fracture with 3 mm of displacement. What is the most appropriate management?

Explanation

Lateral condyle fractures displaced > 2 mm require open reduction and internal fixation to ensure anatomic reduction of the articular surface and physis. This minimizes the risk of nonunion, malunion, and progressive cubitus valgus with tardy ulnar nerve palsy.

Question 54

A 4-year-old child presents with a congenital spinal deformity. Radiographs demonstrate a fully unsegmented unilateral bar with a contralateral hemivertebra at the same level. What is the expected natural history of this specific deformity?

Explanation

An unsegmented bar with a contralateral hemivertebra has the highest risk of rapid and severe progression among congenital scoliosis patterns. Early surgical intervention (in situ fusion or hemivertebra excision with fusion) is essential to prevent severe deformity.

Question 55

A 7-year-old boy with neurofibromatosis type 1 (NF1) presents with a progressive, short, sharp angular thoracic scoliosis. Radiographs demonstrate penciling of the ribs and severe apical wedging. What is the recommended surgical approach if operative intervention is deemed necessary?

Explanation

Dystrophic scoliosis in NF1 has a high rate of progression and pseudoarthrosis. Due to poor bone quality, dural ectasia, and severe angular deformity, a combined anterior and posterior spinal fusion is the recommended surgical treatment to achieve a solid arthrodesis.

Question 56

A 7-year-old boy sustains a forearm injury. Radiographs show a plastic deformation of the ulna and an anterior dislocation of the radial head. According to the Bado classification, what type of Monteggia lesion is this?

Explanation

A Bado Type I Monteggia fracture involves an anterior dislocation of the radial head with a fracture (or plastic deformation in children) of the ulnar diaphysis. It is the most common type of Monteggia lesion in the pediatric population.

Question 57

A 3-year-old girl presents with a painless limp. Examination reveals a positive Trendelenburg sign on the right. Radiographs confirm an untreated, complete right-sided developmental dislocation of the hip (DDH). What is the most appropriate initial definitive management?

Explanation

In a child older than 2 to 3 years with an untreated complete DDH, significant acetabular dysplasia and soft tissue contractures are present. Management typically requires an open reduction, a pelvic osteotomy to correct acetabular dysplasia, and a femoral shortening osteotomy to reduce the joint without excessive pressure.

Question 58

A 14-year-old patient with Marfan syndrome requires surgical correction for a rigid 65-degree scoliotic curve. During preoperative planning, an MRI of the spine is obtained. Which of the following findings is most commonly associated with Marfan syndrome and complicates surgical hardware placement?

Explanation

Dural ectasia (ballooning of the dural sac) is a major criterion for the diagnosis of Marfan syndrome and is present in a majority of these patients. It widens the spinal canal, erodes the pedicles, and complicates the safe placement of pedicle screws.

Question 59

An 8-year-old boy falls on an outstretched hand and sustains a fracture of the radial neck. Radiographs demonstrate 50 degrees of angulation.

What is the most appropriate initial step in management?

Explanation

For pediatric radial neck fractures, angulation greater than 30 degrees typically requires reduction to restore forearm rotation. Initial management should be a closed reduction, followed by percutaneous manipulation or intramedullary pinning if closed reduction fails.

Question 60

A 2-year-old boy is brought to the emergency department after tripping and falling while running on a carpet. Radiographs demonstrate a spiral fracture of the middle third of the femoral shaft. There are no signs of non-accidental trauma. What is the most appropriate treatment?

Explanation

In children ages 6 months to 5 years with isolated, length-stable or minimally shortened diaphyseal femur fractures, early spica casting is the gold standard treatment. It is associated with high union rates and minimal complications.

Question 61

A 12-year-old obese boy presents with acute, severe hip pain and inability to bear weight after a minor twisting injury. Radiographs confirm a severe, unstable slipped capital femoral epiphysis (SCFE). What is the most devastating complication directly associated with the instability of this specific fracture pattern?

Explanation

An unstable SCFE (defined by the inability to bear weight even with crutches) has a significantly higher risk of avascular necrosis (up to 47%) compared to stable slips. The disruption of the precarious retinacular blood supply during the acute slip or forced reduction causes the AVN.

Question 62

A 6-year-old girl sustains an extension-type Gartland III supracondylar humerus fracture. Upon initial clinical evaluation, she is unable to flex the interphalangeal joint of her thumb and the distal interphalangeal joint of her index finger. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar fractures. An AIN palsy presents with the inability to form an 'OK' sign due to weakness of the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 63

During ultrasound screening for DDH in a 6-week-old infant, the Graf classification is utilized. What specifically does the alpha angle measure on the coronal ultrasound image?

Explanation

In the Graf ultrasound method, the alpha angle measures the concavity of the bony acetabular roof relative to the straight iliac bone. An alpha angle greater than 60 degrees is considered normal and indicates adequate bony coverage.

Question 64

A 6-month-old infant is diagnosed with infantile idiopathic scoliosis. Radiographs show a 25-degree left thoracic curve. Which of the following radiographic parameters indicates a high likelihood of curve progression?

Explanation

Mehta's rib-vertebra angle difference (RVAD) greater than 20 degrees is highly predictive of curve progression in infantile idiopathic scoliosis. Phase 2 rib head relation is also a definitive sign of progression.

Question 65

A 4-month-old girl with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the infant exhibits decreased spontaneous movement of the affected side's knee and no active knee extension. What is the most likely cause of this finding?

Explanation

Excessive hip flexion in a Pavlik harness can lead to femoral nerve palsy, presenting as decreased active knee extension. The harness must be adjusted or temporarily discontinued to allow neurological recovery.

Question 66

A 6-year-old boy falls on an outstretched hand and sustains an extension-type supracondylar humerus fracture, which is displaced posteromedially. Which nerve is most commonly at risk with this specific displacement pattern?

Explanation

Posteromedial displacement of an extension-type supracondylar humerus fracture causes the proximal fragment to translate anterolaterally, putting the radial nerve at greatest risk. Posterolateral displacement endangers the anterior interosseous nerve.

Question 67

An 18-month-old girl is diagnosed with residual acetabular dysplasia following successful closed reduction of DDH. Her current acetabular index (AI) is 38 degrees. What is considered the upper limit of normal for the acetabular index at this age?

Explanation

In children older than 1 year, an acetabular index greater than 25 degrees is generally considered abnormal and indicative of dysplasia. Persistent elevation may necessitate a pelvic osteotomy.

Question 68

A 12-year-old boy with Duchenne muscular dystrophy (DMD) has a progressive scoliosis of 45 degrees. His forced vital capacity (FVC) is currently 40% of predicted. What is the most appropriate management?

Explanation

Scoliosis in DMD is rapidly progressive once patients become wheelchair-bound, and bracing is ineffective. Posterior spinal fusion to the pelvis is indicated for curves exceeding 20-30 degrees before pulmonary function severely declines (FVC < 30-35% increases surgical risk).

Question 69

A 13-year-old girl sustains an ankle injury. Radiographs show a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. What is the pathomechanics of this specific fracture?

Explanation

A juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis by the AITFL, caused by an external rotation force. This occurs because the distal tibial physis closes from medial to lateral, leaving the lateral portion vulnerable.

Question 70

A 3-year-old boy presents with a painless limp. Examination shows a positive Trendelenburg gait and Galeazzi sign on the right. Radiographs confirm an untreated right developmental dislocation of the hip. What is the most appropriate surgical management?

Explanation

In a child older than 2-3 years with a completely dislocated hip, closed reduction is usually impossible and carries a high risk of AVN. Treatment typically requires open reduction combined with a femoral shortening osteotomy and a pelvic osteotomy to correct the dysplasia.

Question 71

A 5-year-old boy undergoes open reduction and internal fixation for a displaced lateral condyle fracture of the humerus. Which of the following is the most common complication of this fracture despite anatomic reduction?

Explanation

Lateral spur formation, or lateral condylar overgrowth, is the most common complication following a lateral condyle fracture. Nonunion and cubitus valgus are more severe but less common.

Question 72

A newborn is noted to have congenital scoliosis secondary to a fully segmented hemivertebra at T8. Which of the following organ systems is most critical to evaluate for associated anomalies?

Explanation

Congenital scoliosis is frequently associated with VACTERL anomalies, with genitourinary/renal anomalies occurring in up to 30% of cases. A renal ultrasound is mandatory during the initial evaluation.

Question 73

A 9-month-old infant is brought to the emergency department with a spiral fracture of the midshaft femur. The parents report the child caught his leg in the crib slats. What is the most appropriate next step in management?

Explanation

A femur fracture in a non-ambulatory infant is highly suspicious for non-accidental trauma. A skeletal survey and consultation with child protective services must be initiated before definitive discharge or care.

Question 74

A 13-year-old premenarcheal girl (Risser 0) presents with adolescent idiopathic scoliosis. Radiographs demonstrate a right thoracic curve of 32 degrees. What is the most appropriate treatment recommendation?

Explanation

Bracing is indicated for skeletally immature patients (Risser 0-2) with a curve between 25 and 40 degrees. A TLSO worn for 16 to 23 hours a day is the most effective nonsurgical method to halt curve progression.

Question 75

A newborn with arthrogryposis multiplex congenita is found to have bilateral rigid, dislocated hips. Which of the following statements regarding the management of these hips is most accurate?

Explanation

Teratologic hip dislocations in arthrogryposis are extremely rigid. Bilateral dislocations are frequently left untreated because surgical intervention carries a high risk of severe stiffness, while unreduced bilateral hips still permit functional ambulation.

Question 76

A 2-year-old child presents with a sudden onset of limping and refusal to bear weight on the right leg. There is no history of significant trauma. Physical exam shows mild tenderness over the distal tibia. Initial AP and lateral radiographs are normal. What is the most appropriate initial management?

Explanation

This clinical presentation is classic for a toddler's fracture (undisplaced spiral fracture of the distal tibia), which often does not appear on initial radiographs. Immobilization in a cast or splint with repeat imaging in 10-14 days to identify periosteal reaction is the standard of care.

Question 77

A 14-year-old gymnast presents with chronic low back pain exacerbated by extension. Radiographs show an L5-S1 isthmic spondylolisthesis with 25% slip (Grade 1). She has failed 6 months of conservative management. What is the most appropriate surgical treatment?

Explanation

For low-grade isthmic spondylolisthesis (Grade 1 or 2) that fails conservative care, a posterior/posterolateral fusion in situ without decompression is the gold standard. Pars repair is generally reserved for symptomatic spondylolysis without an active slip.

Question 78

Following closed reduction and spica casting for DDH, a 1-year-old child's radiograph demonstrates failure of the ossific nucleus to appear within 1 year post-reduction. The femoral head appears broad and the neck is short. This presentation is most consistent with which complication?

Explanation

Failure of the ossific nucleus to appear within 1 year, or early signs of a broad head and short neck (coxa brevis), are classic radiographic indicators of avascular necrosis following DDH treatment. It is primarily associated with extreme abduction in the spica cast.

Question 79

A 10-year-old boy sustains a completely displaced Salter-Harris II fracture of the proximal humerus. What is the most acceptable management for this injury?

Explanation

The proximal humerus has massive remodeling potential, contributing to 80% of humeral growth. Therefore, even completely displaced fractures in young children (under 11) can typically be managed conservatively with a sling and swathe, yielding excellent functional results.

Question 80

In the evaluation of typical adolescent idiopathic scoliosis (AIS), which of the following is commonly observed regarding the sagittal profile of the thoracic spine?

Explanation

Adolescent idiopathic scoliosis is a true three-dimensional deformity characterized by a loss of normal kyphosis (hypokyphosis or lordosis) in the sagittal plane at the apex of the thoracic curve. The presence of hyperkyphosis should raise suspicion for non-idiopathic causes like Scheuermann's disease.

Question 81

An 8-year-old boy sustains a mid-diaphyseal both-bone forearm fracture. What is the maximum acceptable angulation that will still allow for functional remodeling without significant loss of forearm rotation?

Explanation

In children younger than 9 years, up to 15 degrees of angulation and complete displacement are generally acceptable in midshaft forearm fractures due to robust remodeling potential. Greater angulation risks a clinically significant loss of pronation and supination.

Question 82

A 6-week-old female infant born breech is evaluated for DDH. Ultrasound examination using the Graf method reveals an alpha angle of 65 degrees and a beta angle of 45 degrees. What is the most appropriate management?

Explanation

According to the Graf ultrasound classification for DDH, an alpha angle greater than 60 degrees and a beta angle less than 55 degrees represent a normal, mature infant hip (Type I). No intervention is necessary.

Question 83

A 12-year-old girl with adolescent idiopathic scoliosis (AIS) presents with a right thoracic curve. She is premenarcheal, Risser 0, and her curve measures 35 degrees on standing PA radiograph. Which of the following is the most appropriate next step in management?

Explanation

Bracing is indicated for skeletally immature patients (Risser 0-2) with AIS curves between 25 and 45 degrees. A TLSO worn for 16-23 hours daily has been shown to significantly decrease the risk of curve progression to the surgical threshold.

Question 84

A 6-week-old female infant, born in the breech presentation, is evaluated for developmental dysplasia of the hip (DDH). Ultrasound reveals an alpha angle of 48 degrees and a beta angle of 80 degrees on the left hip. The hip is stable on clinical exam. What is the most appropriate management?

Explanation

An alpha angle of less than 60 degrees indicates acetabular dysplasia (Graf type II or worse). In a 6-week-old infant with dysplasia, a Pavlik harness is the gold standard initial treatment to promote normal acetabular development.

Question 85

A 6-year-old boy sustains a widely displaced, extension-type supracondylar humerus fracture. Upon presentation, his hand is pink and well-perfused, but he is unable to actively flex the interphalangeal joint of his thumb. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus and the flexor digitorum profundus to the index finger.

Question 86

A 4-year-old girl is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra at T8. Prior to surgical intervention, which of the following imaging studies is most critical to perform?

Explanation

Congenital scoliosis is highly associated with intraspinal anomalies, such as tethered cord, diastematomyelia, and syringomyelia (seen in 20-40% of patients). An MRI of the entire spine is required before any surgical intervention to rule out these anomalies.

Question 87

A 3-year-old child presents with a neglected right developmental dysplasia of the hip (DDH). She undergoes an open reduction, pelvic osteotomy, and femoral shortening osteotomy. Which of the following is the most devastating complication specific to the surgical treatment of DDH?

Explanation

Avascular necrosis of the femoral head is the most severe and specific complication of DDH treatment, often resulting from excessive pressure on the femoral head or disruption of the medial circumflex femoral artery during reduction.

Question 88

A 13-year-old boy presents with ankle pain following a fall. Radiographs demonstrate a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. What is the deforming force and the structure responsible for this avulsion fracture?

Explanation

This describes a Tillaux fracture, which occurs due to an external rotation force. The anterior inferior tibiofibular ligament (AITFL) avulses the anterolateral distal tibial epiphysis, which is the last portion of the physis to close.

Question 89

A 12-year-old non-ambulatory boy with Duchenne muscular dystrophy (DMD) has a progressive thoracolumbar scoliosis measuring 45 degrees. His forced vital capacity (FVC) is currently 40% of predicted. What is the most appropriate management of his spinal deformity?

Explanation

In DMD, scoliosis rapidly progresses once the patient becomes wheelchair-bound. Posterior spinal fusion to the pelvis is indicated for curves >20-30 degrees to improve sitting balance and prevent severe pulmonary decline, provided FVC >30%.

Question 90

A 5-month-old infant with developmental dysplasia of the hip has been treated in a Pavlik harness for 4 weeks. Repeat ultrasound reveals that the left hip remains persistently dislocated. What is the most appropriate next step in management?

Explanation

Failure to achieve reduction in a Pavlik harness after 3-4 weeks requires abandonment of the harness to prevent "Pavlik harness disease" (damage to the posterior acetabular wall). The next step is closed reduction and spica casting under anesthesia.

Question 91

A 6-year-old girl falls on an outstretched arm and sustains a lateral condyle fracture of the distal humerus with 3 mm of displacement. If this fracture goes untreated, what is the most likely late complication?

Explanation

Displaced lateral condyle fractures (>2 mm) require surgical fixation. Nonunion is a common complication of untreated or inadequately treated fractures, which leads to progressive cubitus valgus and subsequent tardy ulnar nerve palsy.

Question 92

An 8-month-old boy is diagnosed with infantile idiopathic scoliosis with a left-sided thoracic curve measuring 25 degrees. The rib-vertebral angle difference (RVAD) of Mehta is 12 degrees. What is the most likely natural history of this curve?

Explanation

Infantile idiopathic scoliosis curves with a Mehta RVAD of less than 20 degrees have a highly favorable prognosis, with the majority undergoing spontaneous resolution. Curves with an RVAD > 20 degrees are likely to progress.

Question 93

A neonate with arthrogryposis multiplex congenita is found to have bilateral teratologic hip dislocations. The hips are stiff and cannot be reduced on physical examination. What is the standard recommendation for management?

Explanation

Teratologic hip dislocations are stiff and irreducible by conservative means (Pavlik harness or simple closed reduction is contraindicated/ineffective). Treatment typically involves open reduction when the infant is older (6-12 months) to allow adequate size for surgery.

Question 94

A 13-year-old boy sustains a Salter-Harris II fracture of the proximal humerus. Radiographs show 40 degrees of apex anterior angulation and 50% translation. What is the most appropriate treatment?

Explanation

The proximal humerus physis provides 80% of the longitudinal growth of the humerus, offering immense remodeling potential. In a 13-year-old, up to 45 degrees of angulation and 50% translation are acceptable and can be managed non-operatively with a sling.

Question 95

A 14-year-old boy presents with progressive thoracic kyphosis and back pain. Standing lateral radiographs reveal a thoracic kyphosis of 65 degrees and anterior wedging of 6 degrees across three consecutive vertebrae. He is Risser 2. What is the most appropriate initial treatment?

Explanation

The patient has Scheuermann's kyphosis. For a skeletally immature patient (Risser < 4) with a progressive curve between 50 and 75 degrees and pain, bracing with an extension orthosis is the recommended treatment to halt progression.

Question 96

During the radiographic evaluation of a 2-year-old child for developmental dysplasia of the hip (DDH), the orthopedist draws a horizontal line connecting the bilateral triradiate cartilages. What is the name of this reference line?

Explanation

Hilgenreiner's line is a horizontal line drawn through the bilateral triradiate cartilages. Perkin's line is drawn perpendicular to Hilgenreiner's line at the lateral edge of the acetabulum, creating quadrants to locate the ossific nucleus of the femoral head.

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

AAOS Pediatric Orthopedic MCQs (Set 3): Scoliosis, DDH & Fractures | 2004 Board Review

Key Takeaway

AAOS Pediatric Orthopedic MCQs (Set 3): Scoliosis, DDH & Fractures | 2004 Board Review

Chapter Index