Orthopedic Pediatrics Board Review 2026: MCQs Part 4

Question 1

A 4-year-old boy sustained a nondisplaced, but complete, fracture of the left proximal tibial metaphysis 1 year ago. The fracture healed uneventfully in an anatomic position. Examination of the injured extremity now reveals 18 degrees of valgus compared with 3 degrees of valgus on the opposite side. Management should now include

Explanation

The development of a valgus deformity after this type of fracture is a well-known occurrence, and the patient's parents should be informed about this risk. In a patient who is age 4 years, the natural history is one of gradual correction by the development of a physiologic varus deformity at the distal tibial physis; therefore, no active intervention is needed at this time. Bracing has no effect on the deformity, and the child is too young for any procedure on the growth plate. Proximal tibial osteotomy is reserved until the patient nears skeletal maturity because of the risk of recurrence of the deformity. Lateral stapling can be done near skeletal maturity if the deformity persists, but this is unlikely to be necessary. Zionts LE, MacEwen GD: Spontaneous improvement of posttraumatic tibia valga. J Bone Joint Surg Am 1986;68:680-687.

Question 2

A 16-year-old boy with spastic quadriplegic cerebral palsy has been referred for evaluation and management of scoliosis. His parents report increasing problems with sitting balance, positioning, and hygiene because of the deformity. The radiograph shown in Figure 46 reveals a lordoscoliosis of 105 degrees with marked pelvic obliquity. Attempts at correcting the pelvic obliquity on supine bending radiographs show significant rigidity. Management should consist of

Explanation

Spinal stabilization is the treatment of choice in patients with severe scoliosis who have progressive positioning, sitting balance, and/or hygiene problems despite maximal nonsurgical management. Pelvic rigidity and marked frontal plane deformity necessitate anterior and posterior procedures so as to maximize correction and fusion. Weinstein SL (ed): The Pediatric Spine: Principles and Practice. New York, NY, Raven Press, 1994, pp 977-997.

Question 3

A 10-year-old boy reports a gradual onset of weakness; however, he is fully ambulatory. History reveals that he has a 17-year-old brother who has just stopped walking because of a similar condition. Laboratory studies show a creatine kinase level of 5,480 IU/L (normal 25 to 232 IU/L), and examination shows a slightly positive Gower sign. What is the most likely diagnosis?

Explanation

The patient has Becker muscular dystrophy. Patients with this condition have a slower rate of progression of disease compared with patients who have Duchenne muscular dystrophy, and walking may continue into the late teens. The creatine kinase level is not as high as in Duchenne muscular dystrophy, which can range from 20,000 to 30,000 IU/L. Becker muscular dystrophy is allelic to Duchenne muscular dystrophy, resulting in a mutation in the dystrophin gene. Myotonic dystrophy is characterized by a progressive inability to relax the muscles after contracture. The Gower sign is not helpful in this disease. Patients with Charcot-Marie-Tooth disease, one type of which is also known as HMSN type II, do not have elevated creatine kinase levels and usually present with a foot deformity. Spinal muscular atrophy, type II, usually presents with severe weakness in the second year of life. Matsuo M: From molecular diagnosis to gene therapy. Brain Dev 1996;18:167-172. Darras BT: Molecular genetics of Duchenne and Becker muscular dystrophy. J Pediatr 1990;117:1-15.

Question 4

Figure 47 shows the radiograph of a 2-day-old girl who has been referred for swelling and limited use of the right upper extremity. The second of twins, the infant was breech and delivered with forceps at age 38 weeks, weighing 5.37 lb. Difficulty in moving the arm was noted shortly after birth. Examination shows no active motion of the shoulder, elbow, or wrist. Active finger flexion and extension are present. The elbow is mildly swollen, and passive motion shows lack of full extension of 20 degrees, lack of full flexion of 15 degrees, and no restriction of pronation or supination. What is the most likely diagnosis?

Explanation

Fractures involving the entire distal humeral physis may be a complication of a difficult delivery. Basing the diagnosis on radiographs can be difficult at this age because the secondary ossification center of the lateral condyle has not developed. The key to the diagnosis is the constant relationship of the radius and ulna, with medial and posterior displacement of the forearm relative to the humerus. An ultrasound can be obtained to confirm the diagnosis in newborns. Because the fracture is through cartilage, examination may reveal only mild swelling, and crepitation may be muffled or not apparent. The lack of apparent active motion of the shoulder, elbow, and wrist is secondary to pseudoparalysis. Child abuse is a common mechanism of this injury in a child who is age 1 month to age 3 years. Beaty JH, Wilkins KE: Fractures involving the entire distal humeral physis, in Rockwood CA, Wilkins KE, Beaty JH (eds): Fractures in Children, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, vol 3, pp 790-801. Dias JJ, Lamont AC, Jones JM: Ultrasonic diagnosis of neonatal separation of the distal humeral epiphysis. J Bone Joint Surg Br 1988;70:825-828.

Question 5

Examination of a 12-year-old girl with a painful flatfoot deformity reveals tenderness in the region of the sinus tarsi and no appreciable subtalar motion. Radiographs are shown in Figures 48a through 48c. Two attempts to relieve her symptoms by cast immobilization fail to relieve the pain. Management should now consist of

Explanation

48b 48c Surgical treatment is indicated for a symptomatic tarsal coalition that has failed to respond to nonsurgical management. In this patient, the radiographs reveal a calcaneonavicular coalition and no degenerative changes. The patient is symptomatic, and two attempts at use of a short leg walking cast have failed to provide relief. For calcaneonavicular coalitions, good results have been reported following resection and interposition of the extensor digitorum brevis. A retrospective study of this procedure achieved good to excellent results in 58 of 75 feet (77%). Degenerative arthritis or persistent pain following resection of a coalition is a reasonable indication for a triple arthodesis. A medial closing wedge osteotomy of the calcaneus may be indicated for a rigid flatfoot with severe valgus deformity. There are no studies documenting the long-term effectiveness of a manipulation under general anesthesia for this condition. Gonzalez P, Kumar SJ: Calcaneonavicular coalition treated by resection and interpostion of the extensor digitorum brevis muscle. J Bone Joint Surg Am 1990;72:71-77.

Question 6

When counseling a patient with hypophosphatemic rickets, which of the following scenarios will always result in a child with the same disorder?

Explanation

Hypophosphatemic rickets is an inherited disorder that is transmitted by a unique sex-linked dominant gene. Therefore, if a male patient has a female offspring, his affected X chromosome will be transmitted and all of his female children will have hypophosphatemic rickets. All male offspring of a male patient will be unaffected. All offspring of a female patient have a 50% chance of having the disorder. Understanding the inheritance of hypophosphatemic rickets facilitates early diagnosis and early treatment. Medical treatment with phosphorus and some types of vitamin D (most authors recommend calcitriol) improves, but does not fully correct, the mineralization defect in hypophosphatemic rickets. However, if medical treatment is begun before the child begins walking, the growth plate is then adequately protected and a bowleg deformity will most likely be prevented. Evans GA, Arulanantham K, Gage JR: Primary hypophosphatemic rickets: Effect of oral phosphate and vitamin D on growth and surgical treatment. J Bone Joint Surg Am 1980;62:1130-1138.

Question 7

A 15-year-old boy with Duchenne muscular dystrophy has a progressive scoliosis that now measures 55 degrees. He is in foster care and is no longer ambulatory. Because posterior spinal fusion with instrumentation is the recommended treatment, the patient participates in a thorough discussion of the risks and benefits of the procedure. However, he refuses the surgery. The physician should now

Explanation

Traditionally, patients have been viewed as ignorant about medical matters and ill-equipped to determine what is in their best interest. This has been especially true for minors. However, recent informed consent policies are now based on the patient's right to self-determination. While most spinal surgeons would agree that spinal fusion improves pulmonary function, sitting balance, and comfort, they would also agree that this comes at considerable risk in a patient with compromised pulmonary function and ultimately, a terminal condition. With increasing frequency, young people older than age 14 years are gaining greater autonomy in decision making about their health care matters. This includes do not resuscitate orders when young patients are terminally ill, as well as in less serious situations. Surgery could be performed with the permission of the legal guardians; however, in this situation it is preferable to follow the patient clinically until he consents to surgery along with the legal guardians. Bracing is contraindicated. Reich WT (ed): Encyclopedia of Bioethics. New York, NY, Simon and Schuster, 1995, pp 1256-1265. Confidential health services for adolescents. Council on Scientific Affairs, American Medical Association. JAMA 1993;269:1420-1424.

Question 8

Figure 49 shows the radiograph of a 3-year-old child with progressive bowlegs. Laboratory studies show a calcium level of 9.5 mg/dL (normal 9.0 to 11.0 mg/dL), a phosphorus level of 4.2 mg/dL (normal 3 to 5.7 mg/dL), and an alkaline phosphatase level of 305 IU/L (normal 104 to 345 IU/L). What is the most likely diagnosis?

Explanation

The patient has bowlegs associated with very wide physes, particularly noted at the hips. The widening of the growth plates is a classic sign of rickets; however, the normal levels of calcium, phosphorus, and alkaline phosphatase rule out both nutritional and hypophosphatemic rickets. Patients with nutritional rickets or hypophosphatemic rickets have hypophosphatemia and increased alkaline phosphatase levels. Jansen metaphyseal dysostosis has very severe radiographic findings that are not found in this patient; however, these radiographic findings are classic for Schmid metaphyseal dysostosis. This disorder is caused by a mutation in the gene for type X collagen, which is found only in the growth plates of growing children. Lachman RS, Rimoin DL, Spranger J: Metaphyseal chondrodysplasia - Schmid type: Clinical and radiographic delineation with a review of the literature. Pediatr Radiol 1988;18:93-102.

Question 9

Figures 50a and 50b show the standing clinical photographs of a 12-year-old boy who has had increasing pain in the left foot for the past 9 months. He reports that the pain is activity related, aching in nature, and localized to the medial aspect of the midfoot and hindfoot. History reveals that he sustained a puncture wound located superior and posterior to the medial malleolus from a plate glass window 18 months ago. Examination reveals no restriction of ankle or subtalar motion, normal neurovascular status, no masses, and a well-healed 1.5-cm laceration posterior to the superior aspect of the medial malleolus. Inversion strength of the foot is decreased to grade 3/5. Radiographs of the foot show no bony abnormalities. Treatment should consist of

Explanation

50b The photographs show a planovalgus posture of the foot. The foot deformity and decreased inversion strength are secondary to laceration of the posterior tibial tendon 18 months ago. If the injury had been recognized acutely, optimal treatment would have consisted of repair of the tendon; however, contracture now precludes that possibility. Therefore, transfer of the flexor digitorum longus or flexor hallucis longus is the preferred treatment. In adults with posterior tibial dysfunction, the entire tendon is typically degenerated and the transfer must be anchored through a drill hole in the navicular. In this patient, the distal end of the posterior tibial tendon is a satisfactory insertion site. Lengthening osteotomy of the calcaneus could be combined with the tendon transfer if the patient had a fixed deformity of the foot. UCBL orthoses and an ankle-foot orthosis are not considered good long-term solutions for a 12-year-old patient. Mosca VS: Flexible flatfoot and skewfoot, in Drennan JC (ed): The Child's Foot and Ankle. New York, NY, Raven Press, 1992, pp 355-376.

Question 10

Which of the following clinical scenarios represents an appropriate indication for convex hemiepiphysiodesis/hemiarthrodesis in the treatment of a child with a congenital spinal deformity?

Explanation

Convex hemiarthrodesis and hemiepiphysiodesis are procedures designed to gradually reduce curve magnitude in congenital scoliosis because of hemivertebrae. They are used to surgically create an anterior and posterior bar to arrest growth on the convexity of the existing deformity. Success of the technique is predicated on continued growth on the concave side of the deformity. Prerequisites for this procedure include curves of limited length (less than or equal to five vertebrae), curves of reasonable magnitude (less than 70 degrees), absence of kyphosis, concave growth potential, and appropriate age (younger than age 5 years).

Question 11

Figures 51a through 51c show the radiographs of a 7-year-old soccer player who reports a gradual onset of midfoot pain that began shortly after the start of soccer season. He states that the pain is worse with activity and is partially alleviated by rest. Examination reveals soft-tissue swelling, and tenderness and warmth in the region of the talonavicular and navicular cunieform joints. Management should consist of

Explanation

51b 51c Osteochondrosis of the tarsal navicular (Kohler disease) is an infrequent cause of midfoot pain in children, and the etiology is unknown. The typical radiographic findings include flattening and irregular ossification of the tarsal navicular. The medial cunieform and talus maintain their normal articular contours. The acute process is best treated with rest and immobilization. A short leg walking cast results in relief of pain and a quicker return to activity compared with orthotics, although long-term success is similar with either method of treatment. Children may return to activities when the symptoms subside. The radiographic appearance of the talus begins to normalize by about 8 to 10 months following the onset of symptoms.

Question 12

A 10-year-old child with cerebral palsy undergoes bilateral hamstring lengthening for severe knee flexion contractures, and knee immobilizers are applied postoperatively. Examination at the initial postoperative check 2 hours after surgery reveals that she can dorsiflex her toes on the right foot, but not on the left foot. The physician should now

Explanation

Children with cerebral palsy are often difficult to examine. However, this patient clearly has a peroneal nerve deficit, most likely from the acute stretch after the hamstring lengthening. The nerve has the best chance of recovery if it is relaxed by flexing the knee. Once the nerve has recovered, gradual knee extension can be accomplished. Aspden RM, Porter RW: Nerve traction during correction of knee flexion deformity: A case report and calculation. J Bone Joint Surg Br 1994;76:471-473.

Question 13

Figures 52a and 52b show the plain radiographs of a 12-year-old girl who has right distal leg pain. She reports that symptoms are present with weight-bearing activities and improve with rest. Examination reveals diffuse tenderness over the distal tibial metaphysis and mild swelling. A photomicrograph of the biopsy specimen is shown in Figure 52c. What is the most likely diagnosis?

Explanation

52b 52c This lytic lesion is in the epiphyseal-metaphyseal region of the distal tibia. The most common lesion in this area is a giant cell tumor. Although these lesions are most commonly seen in adults, they can also occur in the skeletally immature patient. The photomicrograph shows a lesion with multiple giant cells, the nuclei of which are similar to those in the background stroma; this finding is characteristic of giant cell tumors. Giant cells can be seen in many benign lesions, including aneurysmal bone cysts, Brown tumors, and eosinophilic granuloma. These lesions usually have fewer giant cells with less nuclei. The location of this lesion in the epiphyseal-metaphyseal area is not seen in aneurysmal bone cysts, unicameral bone cysts, Ewing's sarcoma, or eosinophilic granuloma.

Question 14

A 15-year-old boy with epilepsy who is treated with phenytoin sustains a vertebral compression fracture during a breakthrough seizure. Radiographs of the spine reveal generalized osteopenia. What is the most likely cause of the osteopenia?

Explanation

As a side effect of treatment, phenytoin induces osteomalacia, or rickets, in growing children, through interference with metabolism of vitamin D. Oral supplementation of vitamin D can minimize this effect in patients who are undergoing prolonged treatment with phenytoin.

Question 15

Figure 53 shows the pedigree of a family with an unusual type of muscular dystrophy. This pedigree is most consistent with what type of inheritance pattern?

Explanation

The pedigree documents involvement of male offspring only, and it also shows transmission through an uninvolved female carrier. This inheritance pattern is most consistent with a x-linked recessive inheritance. It would be inconsistent with a dominant inheritance pattern unless there was incomplete penetrance. Autosomal-recessive inheritance would be possible only if the family member labeled II.F was also a carrier of the same gene; however, this is unlikely. Mitochondrial inheritance is possible, but as with autosomal patterns, mitochondrial inheritance normally affects both male and female offspring. It is transmitted only through the maternal line.

Question 16

Which of the following is considered the most accurate test to determine the amount of limb-length discrepancy in a patient with a knee flexion contracture of 35 degrees?

Explanation

Flexion contractures and angular deformities of a limb cause inaccurate limb-length measurement results with most clinical methods. A CT scanogram is more accurate than standard scanograms for determining limb length in patients with knee flexion contractures of 30 degrees or more. The cost and time necessary to complete the examinations are comparable, but the CT scanogram delivers only 20% of the radiation needed for standard scanograms. Aaron A, Weinstein D, Thickman D, Eilert R: Comparison of orthoroentgenography and computed tomography in the measurement of limb-length discrepancy. J Bone Joint Surg Am 1992;74:897-902.

Question 17

Figures 54a and 54b show the radiograph and MRI scan of a 7-year-old boy who has a painful right thoracic scoliosis that measures 35 degrees. Neurologic examination is normal. Management should consist of

Explanation

54b Because hydrosyringomyelia, with or without an Arnold-Chiari malformation, is now being recognized as the etiology of many infantile and juvenile idiopathic scolioses, management should consist of a neurosurgical consultation. Observation with follow-up radiographs is not an option in curves of this magnitude. A technitium Tc 99m bone scan is unnecessary because the etiology of the curve has been identified. Although spinal fusion may be needed in the future, it should not be undertaken before the neurosurgical problem has been addressed. Zadeh HG, Sakka SA, Powell MP, Mehta MH: Absent superficial abdominal reflexes in children with scoliosis: An early indicator of syringomyelia. J Bone Joint Surg Br 1995;77:762-767. Schwend RM, Hennrikus W, Hall JE, Emans JB: Childhood scoliosis: Clinical indications for magnetic resonance imaging. J Bone Joint Surg Am 1995;77:46-53.

Question 18

A 10-month-old girl has the spinal deformity shown in Figures 55a and 55b with no apparent neurologic finding. The next step in evaluation should be to obtain

Explanation

55b Approximately 60% of patients with a congenital spine abnormality have associated malformations outside the spinal column. Genitourinary abnormalities are probably the most common, occurring in up to 37% of patients. These are usually anatomic anomalies, such as renal agenesis, duplication, fusion, and ectopia. A genitourinary ultrasound is the least invasive screening tool. Other associated anomalies include cervical vertebral abnormalities, VATER syndrome, and intraspinal abnormalities such as diastematomyelia. An MRI scan is not recommended as part of the screening examination; however, if the patient had neurologic signs or symptoms, an MRI scan would be indicated. Beals RK, Robbins JR, Rolfe B: Anomalies associated with vertebral malformations. Spine 1993;18:1329-1332.

Question 19

A 12-year-old girl has scoliosis at T5-T10 that measures 62 degrees. A clinical photograph of the axilla is shown in Figure 56. Management should consist of

Explanation

Neurofibromatosis type 1 (NF-1) is an autosomal-dominant disorder affecting about 1 in 4,000 people. NF-1 causes tumors to grow along various types of nerves and affects the development of non-nervous tissues, such as bone and skin. The gene for NF-1 is located on the long arm of chromosome 17 and codes the protein neurofibromin. Research indicates that NF-1 acts as a tumor-suppressor gene and, as such, plays an important role in the control of cell growth and differentiation. Axillary and inguinal freckling is considered a good diagnostic marker for NF-1. The hyperpigmented spots that measure from 2 mm to 4 mm may be congenital, but these typically appear and increase later in life. Scoliosis is the most common musculoskeletal disorder of NF-1. The curves are frequently dystrophic, kyphotic, and have a high risk of pseudarthrosis following spinal fusion. Anterior and posterior spinal fusion with rigid posterior segmental instrumentation is the treatment of choice. Goldberg Y, Dibbern K, Klein J, Riccardi VM, Graham JM Jr: Neurofibromatosis type 1: An update and review for the primary pediatrician. Clin Pediatr 1996;35:545-561.

Question 20

A 12-year-old girl has bilateral developmentally dislocated hips. History reveals no previous treatment, and she reports no discomfort. Good long-term clinical results are most likely to occur with

Explanation

The natural history of complete developmental dislocation of the hip is dependent on two factors: bilaterality and the presence or absence of a false acetabulum. Patients with bilateral dislocations may have low back pain because of hyperlordosis, but they tend to have less disability than patients with unilateral dislocations who have secondary problems related to limb-length inequality. Degenerative joint disease and clinical disability are most likely to develop in patients with completely dislocated hips and well-developed false acetabula. In a 12-year-old child who has bilateral developmental hip dislocations, it would be difficult to obtain surgical treatment results that are better than the natural history of the disorder. Abductor strengthening exercises are unlikely to influence the long-term outcome in this disorder. Surface replacements are not indicated in young asymptomatic patients. Weinstein SL: Natural history of congenital hip dislocation (CDH) and hip dysplasia. Clin Orthop 1987;225:62-76.

Question 21

Thyroid hormone regulates skeletal growth at the physis by stimulation of

Explanation

Children with hypothyroidism have delayed bone age, reduced thickness of the physis, disorganization of the cartilage columns of the physis, and impaired differentiation of proliferating chondrocytes into hypertrophic cells. As a result, these children have severe growth retardation, and slipped capital femoral epiphysis may develop because of mechanical weakening of the physis. Thyroid hormone regulates terminal differentiation of the growth plate chondrocytes, with a resultant increase in type X collagen and alkaline phosphatase. These substances are important factors in matrix mineralization. Insulin-like growth factors and FGF-2 appear to act synergistically to stimulate mitotic activity of the growth plate chondrocytes. TGF-beta= and PTHrP stimulate proteoglycan synthesis and mitotic activity of the chondrocytes and inhibit type X collagen and alkaline phosphatase activity. Ballock RT: Regulation of skeletal growth and maturation by thyroid hormone, in Buckwalter JA, Ehrlich MG, Sandell LJ, Trippel SB (eds): Skeletal Growth and Development: Clinical Issues and Basic Science Advances. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1998, pp 301-317. Rosier RN, O'Keefe RJ, Reynolds PR, Hicks DG, Puzas JE: Expression and function of TGF-beta= and PTHrP in the growth plate, in Buckwalter JA, Ehrlich MG, Sandell LJ, Trippel SB (eds): Skeletal Growth and Development: Clinical Issues and Basic Science Advances. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1998, pp 285-299.

Question 22

A newborn has an anterolateral bow of the tibia and a duplication of the great toe. Which of the following conditions will develop as the infant grows?

Explanation

Anterolateral bowing of the tibia is normally associated with congenital pseudarthrosis of the tibia. This, in turn, is associated with neurofibromatosis. Posterior bowing is more benign and usually corrects spontaneously. However, anterolateral bowing also corrects spontaneously, and the limb-length discrepancy may be the only remaining sequela when associated with duplication of the great toe. Lisch nodules and axillary freckling are pathognomonic findings in neurofibromatosis but would not be expected in this patient because this type of tibial deformity is not associated with neurofibromatosis.

Question 23

During stabilization of a slipped capital femoral epiphysis, the screw penetrates into the joint. The screw is repositioned so that it is within the femoral head. This transient penetration of the hip joint will most likely lead to

Explanation

Chondrolysis may be associated with unrecognized permanent penetration of the joint space by a pin or screw. However, transient penetration by the guide wire or screw is not associated with this problem. One study described 11 hips in which there was transient intraoperative penetration of the joint space by a guide wire or screw. These patients were followed for at least 2 years, with none showing any clinical or radiographic evidence of chondrolysis. Another retrospective study of 55 slipped epiphyses described 11 hips with transient intraoperative pin penetration, with none showing development of chondrolysis. There are no studies to suggest that transient pin penetration leads to osteonecrosis, stiffness, or premature physeal closure. Zionts LE, Simonian PT, Harvey JP Jr: Transient penetration of the hip joint during in situ cannulated-screw fixation of slipped capital femoral epiphysis. J Bone Joint Surg Am 1991;73:1054-1060.

Question 24

The mother of a 3-month-old infant states that she has difficulty positioning the infant's legs during diaper changes. Examination reveals limited abduction of both hips and a negative Ortolani sign. A radiograph reveals bilaterally dislocated hips. Initial management consists of guided reduction in a Pavlik harness, with weekly follow-up. Figures 57a and 57b show the radiograph and CT scan obtained after 6 weeks in the harness. Management should now consist of

Explanation

57b In an infant younger than age 6 months with a complete dislocation of the hip that is not initially reducible, the Pavlik harness may be used for a trial of guided reduction. When the harness is used in these patients, the infant should be followed at weekly intervals to see if reduction has been achieved. If the hip does not reduce after 3 to 4 weeks of harness wear, the harness should be discontinued, and closed or open reduction should be considered to avoid secondary deformation of the posterolateral acetabulum, also known as Pavlik harness pathology. Changing to other abduction braces is not indicated. Jones GT, Schoenecker PL, Dias LS: Developmental hip dysplasia potentiated by inappropriate use of the Pavlik harness. J Pediatr Orthop 1992;12:722-726. Atar D, Lehman WB, Grant AD: Pavlik harness pathology. Isr J Med Sci 1991;27:325-330.

Question 25

A 6-year-old boy with severe spastic quadriplegic cerebral palsy is nonambulatory. Examination reveals 10 degrees of hip abduction on the left and 30 degrees on the right with the hips and knees extended. The Thomas test shows 20 degrees of flexion bilaterally, and Ely test results are 3+/4 bilaterally. Radiographs show a center edge angle of 0 degrees on the left and -10 degrees on the right. The neck shaft angles are 170 degrees bilaterally. Which of the following procedures would offer the best results?

Explanation

The patient has bilateral subluxated hips, with nearly vertical neck shaft angles; therefore, the treatment of choice is varus derotation osteotomy. Shortening of the bone on one or both sides may be necessary to allow adequate range of motion postoperatively. In patients this age and with this degree of bony deformity, soft-tissue releases are not likely to lead to hip stability. Botulinum toxin has been shown to be effective in the treatment of ankle equinus, but its efficacy in other areas has not been demonstrated as yet. The indications for obturator neurectomy are unclear at present. Proximal femoral resection is a salvage procedure for long-standing hip dislocations that are symptomatic and not reconstructable. Tylkowski CM, Rosenthal RK, Simon SR: Proximal femoral osteotomy in cerebral palsy. Clin Orthop 1980;151:183-192.

Question 26

A 3-week-old boy is undergoing serial casting for idiopathic clubfoot. The physician is preparing to correct the equinus deformity. According to the Ponseti method, what is the correct approach to addressing this deformity?

Explanation

In the Ponseti method, equinus is the final deformity to be corrected. It requires a percutaneous Achilles tenotomy in over 80% of cases, performed only after the cavus, adductus, and varus deformities have been fully corrected and the heel is in valgus.

Question 27

A 13-year-old boy presents with severe groin pain and inability to bear weight on his right leg after a minor fall 2 days ago. Radiographs reveal an unstable slipped capital femoral epiphysis (SCFE). To minimize the risk of avascular necrosis, what is the most appropriate management?

Explanation

Unstable SCFE (inability to bear weight) carries a high risk of avascular necrosis. Current evidence supports urgent stabilization with joint capsulotomy (decompression) or an open reduction via a modified Dunn approach to relieve intracapsular pressure and preserve blood supply.

Question 28

An 8-year-old boy presents with a painless limp and is diagnosed with Legg-Calvé-Perthes disease. Radiographs reveal that the lateral pillar of the femoral head is maintained at 60% of its normal height. According to the Herring classification, what is his group and recommended management?

Explanation

A lateral pillar height of 60% places the patient in Herring Group B (50-100% maintenance). For children 8 years and older at the time of onset, Group B hips show significantly better outcomes with surgical containment compared to conservative management.

Question 29

A 4-week-old girl is being treated with a Pavlik harness for developmental dysplasia of the left hip. At her 2-week follow-up, she is noted to have decreased active extension of the left knee and an absent patellar reflex. What is the most likely cause of this finding?

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hip compressing the nerve against the inguinal ligament. Management involves temporary removal or loosening of the anterior straps.

Question 30

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. Prior to reduction, the hand is pink but pulseless. After closed reduction and percutaneous pinning, the hand remains pink and pulseless with capillary refill of 2 seconds. What is the next best step in management?

Explanation

A 'pink, pulseless' hand following an anatomic reduction of a supracondylar humerus fracture indicates adequate collateral perfusion. Close observation is indicated, as routine vascular exploration is unnecessary unless the hand becomes pale and poorly perfused.

Question 31

A 12-year-old premenarchal girl is evaluated for adolescent idiopathic scoliosis. Radiographs demonstrate a 35-degree right thoracic curve, and her Risser stage is 0. What is the most appropriate management?

Explanation

In a skeletally immature patient (Risser 0-2, premenarchal) with an adolescent idiopathic scoliosis curve between 25 and 40 degrees, rigid bracing (TLSO) is the standard of care to halt curve progression and reduce the need for surgery.

Question 32

A 6-year-old boy with spastic quadriplegic cerebral palsy (GMFCS Level V) is undergoing routine hip surveillance. Radiographs show a migration percentage of 45% bilaterally. He has no pain but exhibits limited hip abduction. What is the most appropriate surgical intervention?

Explanation

In children with cerebral palsy, a hip migration percentage >40% typically indicates failing soft-tissue containment. Bony reconstruction with a proximal femoral VDRO and a pelvic osteotomy (e.g., Dega or San Diego) is required to stabilize the hip.

Question 33

A 4-year-old boy presents with progressive bilateral genu varum. Standing radiographs reveal depression of the medial tibial plateau, metaphyseal beaking, and a metaphyseal-diaphyseal angle of 18 degrees. What is the most appropriate definitive treatment?

Explanation

An MDA >16 degrees confirms the diagnosis of infantile Blount disease. Because the child is 4 years old, bracing is unlikely to be effective, and a proximal tibial valgus osteotomy is the gold standard for realignment and joint preservation.

Question 34

A 14-year-old boy complains of recurrent ankle sprains and chronic lateral foot pain. Examination shows bilateral rigid flatfeet with peroneal spasticity. Oblique radiographs of the foot reveal an 'anteater nose' sign. Which of the following is the most appropriate initial treatment?

Explanation

The 'anteater nose' sign on an oblique radiograph is pathognomonic for a calcaneonavicular coalition. Initial management of symptomatic tarsal coalitions is nonoperative, utilizing a short leg cast or CAM boot to immobilize the joint and reduce inflammation.

Question 35

A 14-year-old nonambulatory boy with Duchenne muscular dystrophy presents with a progressive 35-degree scoliosis. His current forced vital capacity (FVC) is 45% of predicted. What is the recommended management of his spinal deformity?

Explanation

Scoliosis in Duchenne muscular dystrophy progresses rapidly once the child is wheelchair-bound. Posterior spinal fusion to the pelvis is indicated for curves >20-30 degrees while the patient's FVC is still >35%, ensuring they can tolerate the anesthetic and surgery.

Question 36

A 3-year-old girl with recurrent fractures, blue sclerae, and dentinogenesis imperfecta has severe anterolateral bowing of her femurs preventing ambulation. She is diagnosed with osteogenesis imperfecta type III. What is the surgical treatment of choice for her deformities?

Explanation

In osteogenesis imperfecta, severe long bone deformities are best treated with realignment via multiple osteotomies (Sofield-Millar procedure). Fixation with telescopic intramedullary rods (e.g., Fassier-Duval) is preferred as they accommodate patient growth.

Question 37

A 12-year-old obese boy presents with acute left hip pain and inability to bear weight after a minor fall. Radiographs show a severe slipped capital femoral epiphysis. He is unable to walk even with crutches. What is the most significant complication associated with this specific presentation compared to a patient who can bear weight?

Explanation

An unstable SCFE is defined by the inability to bear weight. This presentation carries a significantly higher risk of avascular necrosis (up to 47%) compared to stable SCFE.

Question 38

A 6-week-old infant is being treated with a Pavlik harness for a dislocated left hip. After 4 weeks of strict full-time wear, ultrasound shows the hip remains persistently dislocated. What is the most severe complication of continuing the Pavlik harness in this scenario?

Explanation

Prolonged use of a Pavlik harness in a persistently dislocated hip causes posterior acetabular wear ('Pavlik disease'). The harness should be discontinued after 3 to 4 weeks if reduction is not achieved.

Question 39

During the Ponseti method for the treatment of idiopathic clubfoot, what is the first component of the deformity that must be corrected?

Explanation

The CAVE acronym denotes the sequence of correction: Cavus, Adductus, Varus, Equinus. Cavus is corrected first by supinating the forefoot to align the first ray with the rest of the foot.

Question 40

A 6-year-old boy presents with painless limping. Radiographs show sclerosis and fragmentation of the lateral pillar of the femoral head, with 60% of the lateral pillar height maintained. According to the Herring lateral pillar classification, what is the appropriate group and typical recommendation for this patient?

Explanation

This is a Herring Group B classification (>50% lateral pillar height). In children under 8 years of age, Group B hips generally do well with symptomatic nonoperative management.

Question 41

A 5-year-old girl falls from monkey bars and sustains a widely displaced extension-type supracondylar humerus fracture. On examination, she cannot flex her thumb interphalangeal joint or index finger distal interphalangeal joint. What is the most likely injured nerve structure?

Explanation

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

Question 42

A 14-year-old girl sustains an ankle injury. Radiographs show a fracture of the anterolateral distal tibial epiphysis. What is the primary mechanism of injury for this specific fracture?

Explanation

A Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis. It occurs via external rotation of the foot, which places tension on the anterior inferior tibiofibular ligament.

Question 43

A 4-year-old boy presents with a 2-day history of right hip pain, fever of 38.8°C (101.8°F), and refusal to bear weight. His WBC count is 14,000/mm3 and ESR is 55 mm/hr. According to Kocher's criteria, what is the approximate probability that this child has septic arthritis?

Explanation

The patient has 4 of 4 Kocher criteria (fever >38.5°C, non-weight-bearing, WBC >12,000, ESR >40). This correlates with a 99% probability of septic arthritis.

Question 44

Which of the following is the most significant risk factor for a poor clinical outcome in Legg-Calvé-Perthes disease?

Explanation

Age at onset is the single most important prognostic factor in Legg-Calvé-Perthes disease. Children older than 8 years have less remodeling potential and a higher risk of early osteoarthritis.

Question 45

A newborn boy is noted to have a shortened right lower extremity. Radiographs reveal an absent fibula, anterior bowing of the tibia, and an equinovalgus foot with three toes. What is the most common ankle anomaly associated with this condition?

Explanation

Fibular hemimelia is classically associated with an absent lateral ray, an equinovalgus foot deformity, and a ball-and-socket ankle joint.

Question 46

A 2-year-old child presents with anterior bowing of the left tibia. Radiographs show anterolateral bowing with narrowing of the medullary canal and cortical thickening. The parents report a family history of skin lesions. What is the most likely associated diagnosis?

Explanation

Anterolateral bowing of the tibia is characteristic of congenital pseudarthrosis of the tibia. This condition is strongly associated with Neurofibromatosis type 1.

Question 47

A 10-year-old boy complains of bilateral snapping and pain on the lateral aspect of the right knee during terminal extension. MRI shows a continuous band of meniscal tissue extending from the anterior to the posterior horn. Which type of discoid meniscus is characterized by an absent posterior meniscofemoral attachment?

Explanation

The Wrisberg variant of a discoid meniscus lacks normal posterior capsular attachments. This hypermobility causes the characteristic snapping knee.

Question 48

A 3-year-old girl is diagnosed with a completely displaced diaphyseal femur fracture after a minor fall. She weighs 14 kg (31 lbs). What is the most appropriate initial treatment?

Explanation

For children aged 6 months to 5 years weighing less than 50 lbs, immediate spica casting is the standard of care for diaphyseal femur fractures.

Question 49

A 13-year-old boy with a history of multiple fractures and blue sclerae is being treated for osteogenesis imperfecta with intravenous bisphosphonates. What is the primary mechanism of action of this medication?

Explanation

Bisphosphonates induce osteoclast apoptosis, thereby inhibiting bone resorption. This increases overall bone density and reduces fracture burden in osteogenesis imperfecta.

Question 50

A newborn infant presents with radial longitudinal deficiency (radial clubhand). The parents are counseled regarding associated systemic conditions. Which of the following congenital syndromes is NOT typically associated with this anomaly?

Explanation

Neurofibromatosis type 1 is not associated with radial clubhand. TAR, Holt-Oram, VACTERL, and Fanconi anemia are classically associated syndromes.

Question 51

A 14-year-old boy presents with a painful flatfoot and recurrent ankle sprains. Radiographs show a "C-sign" on the lateral view of the ankle. What is the best imaging modality to confirm the suspected diagnosis and assess its extent?

Explanation

The "C-sign" on lateral plain radiographs indicates a talocalcaneal coalition. A CT scan is the gold standard to define the size, location, and osseous nature of tarsal coalitions.

Question 52

A 12-year-old girl with adolescent idiopathic scoliosis presents with a right thoracic curve. She has not reached menarche and her Risser stage is 0. Her curve measures 35 degrees. What is the most appropriate management?

Explanation

In a skeletally immature patient (premenarchal, Risser 0-2) with a progressive curve between 25 and 45 degrees, bracing is the standard of care to prevent further progression.

Question 53

A 7-year-old boy has an isolated, closed midshaft fracture of the radius and ulna with 20 degrees of apex volar angulation. What is the maximum acceptable angulation for a diaphyseal both-bone forearm fracture in a child of this age?

Explanation

For children under 9 years old, up to 15 degrees of angulation and 45 degrees of malrotation are acceptable due to their immense remodeling potential.

Question 54

An 8-year-old boy presents with a mass in the popliteal fossa. The mass is painless, transilluminates, and is most prominent with the knee fully extended. What is the most appropriate management for this condition?

Explanation

Pediatric popliteal (Baker's) cysts rarely communicate with the joint and almost never indicate intra-articular pathology. Observation and reassurance are indicated as they typically resolve spontaneously.

Question 55

A 6-month-old girl is noted to have her head consistently tilted to the right and rotated to the left. A palpable mass is present in the right neck. What is the primary muscle involved in this condition?

Explanation

Congenital muscular torticollis results from contracture of the sternocleidomastoid muscle. It presents with ipsilateral head tilt and contralateral rotation.

Question 56

A 12-year-old boy with a BMI in the 95th percentile undergoes in situ pinning of a left stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest clinical or radiographic predictor for determining the risk of a contralateral slip, warranting prophylactic pinning?

Explanation

The status of the triradiate cartilage (modified Oxford bone age) is the strongest predictor of bilateral SCFE. Patients with an open triradiate cartilage or younger chronological age (typically <10 years) are at the highest risk for developing a contralateral slip.

Question 57

A 5-week-old female with an irreducible developmental dysplasia of the hip (DDH) is treated with a Pavlik harness. At her 3-week ultrasound follow-up, the hip remains dislocated. What is the most appropriate next step in management?

Explanation

Failure to achieve reduction in a Pavlik harness after 3 to 4 weeks is an indication to abandon the harness to prevent 'Pavlik disease' (acetabular erosion) and transition to a closed reduction and spica casting, or alternatively, trial a rigid abduction orthosis.

Question 58

A 4-year-old boy treated successfully with the Ponseti method for idiopathic clubfoot now presents with dynamic supination of the foot during the swing phase of gait. Passive range of motion of the foot and ankle is fully correctable. What is the standard surgical management for this relapse?

Explanation

Dynamic supination during the swing phase in a patient treated with the Ponseti method is best managed by a full anterior tibial tendon transfer to the lateral (third) cuneiform. A split transfer (SPLATT) is generally contraindicated in idiopathic clubfoot as it can tether the foot.

Question 59

An 11-year-old girl with primary hypothyroidism presents with unilateral groin pain and a limp. Radiographs demonstrate a mild slipped capital femoral epiphysis (SCFE) of the symptomatic hip. What is the most appropriate management?

Explanation

Patients with endocrine disorders, such as hypothyroidism, have a significantly higher risk of bilateral SCFE. Prophylactic pinning of the contralateral asymptomatic hip is strongly indicated to prevent subsequent displacement.

Question 60

A 5-month-old girl with developmental dysplasia of the hip (DDH) has been treated with a Pavlik harness for 4 weeks. Repeat ultrasound reveals an alpha angle of 45 degrees, and the hip remains persistently subluxated. What is the next most appropriate step in management?

Explanation

Continuing a Pavlik harness in an persistently dislocated or subluxated hip beyond 3 to 4 weeks risks 'Pavlik harness disease' (posterior acetabular wear). Transitioning to a rigid abduction orthosis (e.g., Rhino cruiser) or proceeding to closed reduction and spica casting is the standard next step.

Question 61

An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs classify the hip as Lateral Pillar B/C. According to current evidence-based guidelines, which treatment yields the best radiographic outcome for this patient?

Explanation

For children over the age of 8 with Lateral Pillar B or B/C involvement, surgical containment provides superior radiographic outcomes compared to nonoperative management. Osteotomies redirect the femoral head into the acetabulum to maintain sphericity during the healing phase.

Question 62

A 3-year-old boy previously treated with the Ponseti method for bilateral idiopathic clubfeet presents with a relapsed deformity. Gait evaluation reveals dynamic supination of the foot during the swing phase. What is the most appropriate surgical intervention?

Explanation

Dynamic supination during the swing phase is a classic sign of relapsed clubfoot following Ponseti casting. Transferring the tibialis anterior tendon to the lateral cuneiform balances the foot and minimizes further relapse.

Question 63

A 6-year-old boy sustains an extension-type Gartland III supracondylar humerus fracture. Upon initial presentation, the hand is pink but pulseless. After anatomical closed reduction and percutaneous pinning, the hand remains pink and well-perfused, but the radial pulse remains absent. What is the next best step?

Explanation

A pink, pulseless hand after an anatomic reduction of a supracondylar fracture indicates adequate collateral perfusion. The standard of care is close observation, as the pulse often returns spontaneously within 24 to 48 hours without the need for vascular exploration.

Question 64

An 8-year-old girl with spastic diplegic cerebral palsy is evaluated for progressive hip subluxation. Pelvic radiographs show a migration percentage of 45% bilaterally. What is the recommended management?

Explanation

In children with spastic cerebral palsy, a hip migration percentage greater than 40% usually dictates bony reconstructive surgery. Bilateral varus derotational osteotomies (VDRO), often combined with pelvic osteotomies, provide the necessary correction to stabilize the hips.

Question 65

A 3-year-old girl has been treated with a knee-ankle-foot orthosis (KAFO) for infantile Blount disease (Langenskiöld stage II) for the past 12 months. Radiographs demonstrate progressive bilateral tibia vara. What is the most appropriate next step in management?

Explanation

Infantile Blount disease that fails to improve after 12 months of bracing requires surgical intervention. Performing a proximal tibial valgus osteotomy by age 3 to 4 corrects the deformity and helps prevent irreversible medial physeal damage.

Question 66

A 9-year-old boy (Tanner stage 1) sustains a complete anterior cruciate ligament (ACL) tear. He experiences recurrent instability episodes despite 3 months of physical therapy. Which surgical option minimizes the risk of growth arrest?

Explanation

In prepubescent children (Tanner stage 1) with recurrent instability, an all-epiphyseal or extra-articular physeal-sparing reconstruction minimizes the risk of premature growth arrest. Delaying surgery until skeletal maturity significantly increases the risk of secondary meniscal and chondral damage.

Question 67

A 13-year-old boy presents with a rigid flatfoot and recurrent ankle sprains. A CT scan confirms a talocalcaneal coalition involving 25% of the posterior facet with no degenerative changes. He has failed 6 months of conservative management with casting and orthotics. What is the best definitive treatment?

Explanation

For a symptomatic talocalcaneal coalition involving less than 50% of the posterior facet without arthritic changes, surgical resection with interposition (fat or muscle) is the treatment of choice. Arthrodesis is reserved for larger coalitions (>50%) or cases with significant degenerative arthritis.

Question 68

A 13-year-old premenarchal girl (Risser stage 0) is diagnosed with a right thoracic adolescent idiopathic scoliosis measuring 35 degrees on standing radiographs. What is the most appropriate initial management?

Explanation

TLSO bracing is indicated for skeletally immature patients (Risser 0-2) with adolescent idiopathic scoliosis curves between 25 and 45 degrees. Bracing effectively halts curve progression and reduces the need for surgical intervention when compliance is high.

Question 69

An 8-year-old boy falls on an outstretched hand and sustains a radial neck fracture. Radiographs reveal 25 degrees of angulation. What is the most appropriate management?

Explanation

In children younger than 10 years, up to 30 degrees of radial neck angulation is acceptable due to their excellent remodeling potential. Therefore, observation and cast immobilization are the most appropriate initial management steps.

Question 70

An 18-month-old boy is evaluated for anterolateral bowing of the tibia. Radiographs demonstrate a sclerotic, narrowed tibial diaphysis consistent with impending congenital pseudarthrosis. Which systemic condition is most strongly associated with this finding?

Explanation

Anterolateral bowing of the tibia and congenital pseudarthrosis of the tibia (CPT) are hallmark musculoskeletal manifestations of Neurofibromatosis type 1. This condition is caused by a mutation in the neurofibromin gene on chromosome 17.

Question 71

A 14-year-old boy presents with an ankle injury after falling off a skateboard. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibia. Avulsion of which ligament is responsible for this fracture pattern?

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It is caused by an avulsion of the anterior inferior tibiofibular ligament (AITFL) occurring because the medial aspect of the distal tibial physis closes before the lateral aspect.

Question 72

A 5-year-old boy presents with an atraumatic limp and refuses to bear weight on his right leg. His temperature is 38.0°C (100.4°F), WBC count is 13,000/mm³, and ESR is 45 mm/hr. According to the Kocher criteria, what is the approximate probability that this child has septic arthritis of the hip?

Explanation

This patient meets three of the four Kocher criteria: non-weight-bearing, WBC >12,000/mm³, and ESR >40 mm/hr (his temperature is below the 38.5°C threshold). Having three criteria yields a 93% probability of septic arthritis.

Question 73

A 14-year-old gymnast presents with persistent low back pain and radiculopathy. Radiographs show a grade II L5-S1 isthmic spondylolisthesis. She has failed 6 months of nonoperative management. What is the best surgical option?

Explanation

For adolescents with a symptomatic low-grade (Grade I or II) isthmic spondylolisthesis that fails conservative management, L5-S1 posterior instrumented fusion in situ is the gold standard. Attempting full reduction in low-grade slips unnecessarily increases the risk of iatrogenic L5 nerve root injury.

Question 74

A 13-year-old boy presents to the emergency department with acute right hip pain after a minor fall. He is unable to bear weight. Radiographs demonstrate a slipped capital femoral epiphysis (SCFE) with 40 degrees of slip. What is the most significant risk associated with this specific presentation compared to a patient who is able to bear weight?

Explanation

This patient has an unstable SCFE, defined by the inability to bear weight even with crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (AVN), up to 50%, compared to nearly 0% in stable SCFE.

Question 75

A 6-week-old female infant is referred for an ultrasound of the hips due to a breech presentation. The ultrasound report notes an alpha angle of 50 degrees and a beta angle of 65 degrees. According to the Graf classification, what is the most appropriate management for this patient?

Explanation

An alpha angle less than 60 degrees indicates developmental dysplasia of the hip (Graf Type IIb or worse depending on age and specific angle). Treatment with a Pavlik harness is indicated for dysplastic hips in infants younger than 6 months.

Question 76

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

Explanation

For a pink, pulseless hand following anatomic reduction and pinning of a supracondylar humerus fracture, close clinical observation is the standard of care. Arterial exploration is indicated if the hand becomes pale and poorly perfused.

Question 77

A 4-year-old boy with a history of right idiopathic clubfoot treated successfully with the Ponseti method presents with a new gait abnormality. His parents note that he walks on the outside of his right foot. Examination reveals dynamic supination during the swing phase of gait, but the foot is passively correctable. What is the most appropriate surgical intervention?

Explanation

Dynamic supination in a previously corrected clubfoot is typically caused by an overactive tibialis anterior muscle. The treatment of choice for a flexible deformity in this age group is transfer of the entire tibialis anterior tendon to the lateral cuneiform.

Question 78

A 14-year-old boy presents with vague midfoot pain and a history of recurrent ankle sprains. Examination shows a rigid pes planovalgus foot with restricted subtalar motion. CT scan demonstrates a talocalcaneal coalition involving 60 percent of the middle facet, with degenerative changes in the posterior facet. What is the most appropriate definitive management?

Explanation

Resection of a talocalcaneal coalition is generally contraindicated if it involves greater than 50 percent of the middle facet or if degenerative changes are present in the posterior facet. Subtalar arthrodesis is the treatment of choice in this scenario.

Question 79

An 8-month-old infant with achondroplasia is noted by her parents to have episodes of apnea during sleep. She also exhibits brisk lower extremity reflexes and sustained clonus. Which of the following diagnostic studies is most urgent?

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis, which can lead to cervicomedullary compression, central sleep apnea, hyperreflexia, and sudden death. Urgent MRI of the craniocervical junction is required to assess the need for foramen magnum decompression.

Question 80

A 4-year-old girl is evaluated for worsening bilateral genu varum. Radiographs demonstrate an abrupt medial angulation of the proximal tibial metaphysis with depression of the medial aspect of the physis, consistent with Langenskiold stage III infantile Blount disease. Conservative management with bracing has failed. What is the most appropriate next step in management?

Explanation

For Langenskiold stage III infantile Blount disease in a 4-year-old child where bracing has failed, a proximal tibial valgus-producing osteotomy (with fibular osteotomy) is the gold standard. Guided growth alone is less reliable in advanced stages with significant physeal depression.

Question 81

A 12-year-old obese boy presents with sudden inability to bear weight on his left leg after a minor fall. Radiographs show a severe left slipped capital femoral epiphysis (SCFE). He has a known medical history of panhypopituitarism. What is the most appropriate management for the contralateral, asymptomatic right hip?

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine disorders, such as panhypopituitarism, due to the high risk of bilateral involvement. Bilateral slips can occur in up to 100% of patients with certain endocrinopathies.

Question 82

A 3-year-old boy treated successfully for idiopathic clubfoot as an infant using the Ponseti method presents with a relapsed deformity. His parents report compliance with bracing until age 2. On examination, he has dynamic supination during the swing phase of gait. Which of the following is the most appropriate surgical management?

Explanation

Dynamic supination in a relapsed clubfoot treated via the Ponseti method is best managed with a transfer of the entire tibialis anterior tendon to the lateral cuneiform. A SPLATT is typically reserved for spastic conditions like cerebral palsy.

Question 83

A 6-year-old girl sustains a severely displaced extension-type supracondylar humerus fracture. On initial presentation, her hand is pink and warm, but the radial pulse is absent. After closed reduction and percutaneous pinning, the hand remains pink with brisk capillary refill, but the radial pulse is still absent on Doppler ultrasound. What is the most appropriate next step in management?

Explanation

A "pulseless, pink hand" following anatomical reduction and pinning of a supracondylar humerus fracture can be safely observed if perfusion is clinically adequate (capillary refill <2 seconds). Vascular exploration is indicated only if the hand becomes dysvascular (cool, pale) after reduction.

Question 84

An 18-month-old girl presents with a limp. Pelvic radiographs reveal a dislocated left hip with a false acetabulum and an acetabular index of 42 degrees. Which of the following is the most appropriate primary surgical management?

Explanation

In children older than 18 months with untreated Developmental Dysplasia of the Hip (DDH), closed reduction has a high failure rate and elevated risk of osteonecrosis. The standard of care is open reduction, often combined with a pelvic osteotomy (e.g., Salter) to address significant residual acetabular dysplasia.

Question 85

A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs reveal fragmentation of the capital femoral epiphysis with >50% maintenance of the lateral pillar height. According to the Herring lateral pillar classification, what is his group and expected outcome without surgical intervention?

Explanation

According to the Herring classification, maintenance of >50% of the lateral pillar height defines Group B. Children diagnosed before age 8 with Group B LCPD generally have good outcomes with conservative management and rarely require surgical containment.

Question 86

A 10-year-old girl with Spinal Muscular Atrophy (SMA) type 2 presents with progressive neuromuscular scoliosis of 65 degrees. She is currently receiving intrathecal nusinersen treatments. What is a critical technical consideration when planning posterior spinal fusion for this patient?

Explanation

Patients with SMA receiving nusinersen require ongoing lifelong intrathecal access for drug delivery. When performing a posterior spinal fusion, leaving an interlaminar window (e.g., at L3-L4) un-fused and free of bone graft is critical to allow for continued administration.

Question 87

A 13-year-old girl sustains a twisting ankle injury. Radiographs show an isolated Salter-Harris III fracture of the anterolateral distal tibial epiphysis with 3 mm of displacement. What is the pathomechanics of this specific injury pattern?

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs due to avulsion by the anterior inferior tibiofibular ligament (AITFL) as the distal tibial physis closes in an asymmetric, predictable pattern (central, medial, then lateral).

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

Orthopedic Pediatrics 2026 MCQs: Board Review Questions & Answers (Part 4)

Key Takeaway

Orthopedic Pediatrics 2026 MCQs: Board Review Questions & Answers (Part 4)

Chapter Index