Orthopedic Pediatrics 2026 MCQs: Board Review Part 2

Question 1

Figure 17 shows the radiograph of a 2-year-old girl who sustained a fracture of the femur in a fall while walking with her parents. History reveals that this is her third long bone fracture, having sustained a humerus fracture 1 year ago and a fracture of the opposite femur 9 months ago. There is no family history of any similar problem. Examination reveals distinctly blue sclerae, normal appearing teeth, and no skin lesions. What is the most likely cause of this patient's disorder?

Explanation

Osteogenesis imperfecta (OI) is a genetically determined disorder of type I collagen synthesis that is characterized by bone fragility. This patient has had three fractures of the long bones by age 2 years, with the last one occurring after relatively minor trauma. The patient's history and clinical features are consistent with a diagnosis of Sillence type IA OI. Type I OI is the mildest and most common form. Inheritance is autosomal-dominant; however, as in this patient, new mutations are frequent. Type I is subclassified into the A type (absence of dentinogenesis imperfecta) and B type (presence of dentinogenesis imperfecta). The sclerae are blue, and the first fractures usually occur in the preschool years after walking has begun. Cells from individuals with type I OI largely demonstrate a quantitative defect of type I collagen; they synthesize and secrete about half the normal amount of type I procollagen. Qualitative mutations that lead to an abnormal type I procollagen molecule result in more severe types of the disorder. There are no indications that this child has been abused. Radiographs of the femur show no evidence of rickets, pyknodysostosis, or osteopetrosis. Morquio syndrome, characterized by excess excretion of keratin sulfate in the urine, is not associated with bone fragility. Kocher MS, Shapiro F: Osteogenesis imperfecta. J Am Acad Orthop Surg 1998;6:225-236. Sillence DO, Senn A, Danks DM: Osteogenesis imperfecta: An expanding panorama of variants. Clin Orthop 1981;159:11-25.

Question 2

An 8-year-old boy with severe hemophilia A (factor VIII) and no inhibitor is averaging eight transfusions per month for bleeding into the right ankle. Examination shows synovial hypertrophy; range of motion consists of 0 degrees of dorsiflexion and 20 degrees of plantar flexion. The patient's knees, elbows, and left ankle have no restriction of motion. Standing radiographs of the right ankle are shown in Figure 18. Management should consist of

Explanation

The patient has bilateral hypertrophic synovitis that is causing repeated hemarthroses and progressive arthropathy. Ankle synovectomy in patients with hemophilia is effective in significantly reducing the rate of joint bleeding and in slowing the progression of the arthropathy; therefore, bilateral synovectomies is the treatment of choice. Range of motion can be effectively maintained after ankle synovectomy. Bracing and prophylactic transfusions would be ineffective at this time. Ankle arthrodesis should be reserved for patients with severe pain. Compared with patients who have juvenile rheumatoid arthritis, patients with hemophilia generally do not have involvement of the subtalar joint and rarely require a pantalar arthrodesis. Greene WB: Synovectomy of the ankle for hemophilic arthropathy. J Bone Joint Surg Am 1994;76:812-819.

Question 3

Figures 19a through 19c show radiographs of the cervical spine of an asymptomatic patient with Down syndrome who wants to participate in a Special Olympics running event. The neurologic examination is normal. Management should consist of

Explanation

19b 19c An atlanto-dens interval (ADI) of up to 4 mm in children is considered normal. Children with Down syndrome have increased ligamentous laxity, with atlantoaxial instability occurring in as many as 15% to 20% of patients. These patients are at risk for catastrophic injury following minor trauma and should be routinely screened for instability, generally beginning when the patient starts to walk. Patients with an ADI of greater than 5 mm should avoid contact sports and high-risk activities such as gymnastics, diving, the high jump, and the butterfly stroke. The American Academy of Pediatrics Committee of Sports Medicine and Fitness guidelines recommend that lateral views of the cervical spine in neutral, flexion, and extension should be obtained in all children with Down syndrome who wish to participate in sports. Patients with normal radiographs and examinations do not need repeat radiographs, although some authors suggest that instability increases with age, and therefore recommend repeat radiographs every 5 years. Cervical spine fusion in patients with Down syndrome has a high rate of complications and should be performed only on patients with symptoms and evidence of myelopathy. American Academy of Pediatrics Committee of Sports Medicine and Fitness: Atlantoaxial instability in Down syndrome. Pediatrics 1995;96:151-154. Copley LA, Dormans JP: Cervical spine disorders in infants and children. J Am Acad Orthop Surg 1998;6:204-214.

Question 4

Compared with amputation, limb salvage for osteosarcoma of the distal end of the femur will result in

Explanation

Major advances in diagnostic imaging, neoadjuvant chemotherapy, and surgical techniques have allowed limb salvage to be performed as an alternative to amputation in children with osteosarcoma. The outcome of treatment of nonmetastatic, high-grade osteosarcoma of the distal femur was studied in 227 patients from 26 institutions. The authors found no difference in the long-term survival or quality of life between patients treated with limb salvage and those treated with amputation. Patients treated with limb salvage had a higher rate of reoperation, but a better functional outcome. Rougraff BT, Simon MA, Kneisl JS, Greenberg DB, Mankin HJ: Limb salvage compared with amputation for osteosarcoma of the distal end of the femur: A long-term oncological, functional, and quality-of-life study. J Bone Joint Surg Am 1994;76:649-656.

Question 5

Examination of a 7-year-old boy reveals 20 degrees of valgus following a lawn mower injury to the lateral femoral epiphysis. Treatment consists of total distal femoral epiphyseodesis and varus osteotomy. Following surgery, he has a limb-length discrepancy of 3 cm and 5 degrees of genu valgum. Assuming that he undergoes no further treatment, the patient's predicted limb-length discrepancy at maturity would be how many centimeters?

Explanation

The distal femoral epiphysis grows approximately 1 cm per year and in boys, growth ceases at approximately age 16 years. Therefore, the patient's limb-length discrepancy at maturity would be 12 cm (9 cm plus the 3-cm discrepancy he has from the previous surgery). Little DG, Nigo L, Aiona MD: Deficiencies of current methods for the timing of epiphyseodesis. J Pediatr Orthop 1996;16:173-179.

Question 6

When the iliac apophysis starts ossifying in the normal adolescent, growth of the sitting height or trunk height is characterized by

Explanation

Studies by Anderson and associates have resulted in a growth-remaining chart for sitting height that shows an increase of 3 to 5 cm in girls and an increase of 5 to 8 cm in boys. Future growth of the spine may impact brace longevity and fit. Anderson M, Hwang SC, Green WT: Growth of the normal trunk in boys and girls during the second decade of life: Related to age, maturity, and ossification of the iliac epiphyses. J Bone Joint Surg Am 1965;47:1554-1564.

Question 7

A 10-year-old girl was thrown over the handlebars of her bicycle and landed directly on her left shoulder. She was treated with a figure-of-8 strap and analgesics. Follow-up examination 2 weeks later reveals that the lateral end of the clavicle is superiorly dislocated relative to the acromion. A radiograph of the shoulder shows calcification lateral to the coracoid process at the level of the acromion, and the clavicle is superiorly displaced. Management should consist of

Explanation

In adults, a direct blow on the acromion usually results in an acromioclavicular dislocation. In children, however, the usual injury from this mechanism is a physeal fracture of the lateral clavicle. The clavicular shaft fragment, analogous to the metaphyseal portion of a physeal fracture, herniates through the periosteum, leaving the distal periosteal sleeve in contact with the lateral (distal) physeal fragment. The treatment of choice is immobilization until the patient is pain-free. Falstie-Jensen S, Mikkelsen P: Pseudodislocation of the acromioclavicular joint. J Bone Joint Surg Br 1982;64:368-369.

Question 8

Figures 20a and 20b show the radiographs of an obese 15-year-old boy who has severe left groin pain and is unable to bear weight following a minor injury. Treatment should consist of

Explanation

20b The radiographs and history are consistent with an acute unstable slipped capital femoral epiphysis. Aronson and Loder documented an increased rate of osteonecrosis associated with manipulative reduction. They recommended bed rest with skin traction to allow the synovitis to resolve, followed by in situ pinning. They noted, however, that many of these slips reduced with anesthesia and positioning on a fracture table. Biomechanic studies have shown a slight increased resistance to shear stress when two screws are used, but it is unknown if this is significant in the clinical setting. Open epiphyseodesis does not provide postoperative stability; therefore, adjunctive fixation or immobilization is required. Numerous studies have noted the inadvisability of using multiple screws. Casting has a high rate of complications, including chondrolysis and progression of the slip. Aronson DD, Loder RT: Treatment of the unstable (acute) slipped capital femoral epiphysis. Clin Orthop 1996;322:99-110. Karol LA, Doane RM, Cornicelli SF, Zak PA, Haut RC, Manoli A II: Single versus double screw fixation for treatment of slipped capital femoral epiphysis: A biomechanical analysis. J Pediatr Orthop 1992;12:741-745.

Question 9

What is the recommended treatment of a skeletally immature 12-year-old boy who has an anterior cruciate ligament-deficient knee?

Explanation

Traditional surgeries for anterior cruciate ligament-deficient knees carry the potential risk of premature physeal closure in young athletes. Therefore, most surgeons are reluctant to recommend intra-articular reconstruction using bone tunnels with bone-patellar tendon-bone autografts or hamstring tendons. The current recommendation for young athletes is activity modification, rehabilitation, and functional bracing until the patient is near skeletal maturity. At that time, for the very symptomatic patient, the treatment of choice is intra-articular repair of the anterior cruciate ligament. If a skeletally immature patient continues to have instability despite rehabilitation and bracing, a modification of the femoral tunnel to the over-the-top position will not place the lateral femoral physis at risk for premature closure and deformity. A centrally placed tibial tunnel will minimize the risk of angular deformity and minimize limb-length discrepancy if physeal arrest occurs. Barry P: Anterior cruciate ligament injuries, in Andrews JR, Timmerman LA (eds): Diagnostic and Operative Arthroscopy. Philadelphia, Pa, WB Saunders, 1997, p 358. McCarroll JR, Shelbourne KD, Porter DA, Rettig AC, Murray S: Patellar tendon graft reconstruction for midsubstance anterior cruciate ligament rupture in junior high school athletes: An algorithm for management. Am J Sports Med 1994;22:478-484. Nottage WM, Matsuura PA: Management of complete traumatic anterior cruciate ligament tears in the skeletally immature patient: Current concepts and review of the literature. Arthroscopy 1994;10:569-573.

Question 10

Figures 21a and 21b show the radiographs of a 12-year-old patient with an L4-level myelomeningocele who has scoliosis that has been slowly progressing for the past several years. There has been no loss of motor function. An MRI scan shows no syringomyelia or increased hydrocephalus. Management should consist of

Explanation

21b Scoliosis is a common occurrence in children with myelomeningocele, with the incidence increasing as the neurologic level moves cephalad. The rate of pseudarthrosis for isolated anterior or posterior fusions has been reported as high as 75%. The combination of anterior and posterior fusions with some type of instrumentation has been shown to decrease the rate of pseudarthrosis to 20%. Brace treatment in smaller curves can be used as a temporizing measure to delay surgery, but as with idiopathic scoliosis, the brace is ineffective for larger curves. Observation is not indicated with a curve of this magnitude. Ward WT, Wenger DR, Roach JW: Surgical correction of myelomeningocele scoliosis: A critical appraisal of various spinal instrumentation systems. J Pediatr Orthop 1989;9:262-268.

Question 11

A 3-year-old child is referred for evaluation of bowed legs. History reveals no dietary deficiencies; however, family history is significant for several members with bowed legs. Examination reveals genu varum, and the child is in the 5th percentile for height and weight. Laboratory studies show normal renal function, a normal calcium level, a decreased phosphate level, and an elevated alkaline phosphatase level. A plain radiograph of the lower extremities is shown in Figure 22. What is the most likely diagnosis?

Explanation

The differential diagnosis of genu varum includes physiologic genu varum, Blount's disease, skeletal dysplasia, and metabolic bone disease. Children with Blount's disease are generally in the 95th percentile for height and weight, and usually multiple family members are not affected. The radiographs show widening of the physis and metaphyseal flaring. In Blount's disease, the characteristic radiographic changes involve only the tibia, and at this age, most commonly show beaking of the medial metaphysis. Skeletal dysplasias, such as chondrometaphyseal dysplasia, are associated with short stature, and the radiographic changes are similar to those seen here. However, laboratory studies in these children will be within normal limits. Children with chronic renal disease will often be of short stature, and the radiographic findings are again similar to those shown here. However, BUN and creatinine levels are elevated and phosphate levels are elevated rather than decreased in children with renal disease. The absence of dietary deficiencies and positive family history rules out vitamin D-deficient rickets. There are four types of vitamin D-resistant rickets: failure of production of 1,25-dihydroxy vitamin D, phosphate diabetes (hypophosphatemic rickets), end organ insensitivity to vitamin D, and renal tubular acidosis. All types of vitamin D-resistant rickets are resistant to treatment with physiologic doses of vitamin D. The patient's clinical picture, family history, laboratory studies, and radiographs are most consistent with hypophosphatemic rickets. This entity is inherited as a sex-linked dominant trait. 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. Loeffler RD Jr, Sherman FC: The effect of treatment on growth and deformity in hypophosphatemic vitamin D-resistant rickets. Clin Orthop 1982;162:4-10. Loder RT, Johnston CE II: Infantile tibia vara. J Pediatr Orthop 1987;7:639-646.

Question 12

A 14-year-old boy sustained a femoral neck fracture in a fall from a tree and underwent open reduction and internal fixation 6 months ago. Follow-up examination now reveals an antalgic Trendelenburg gait and painful range of motion. A radiograph is shown in Figure 23, and a CT scan shows a nonunion. Treatment should consist of

Explanation

The coxa vara deformity and fracture nonunion should be treated simultaneously; therefore, the treatment of choice is curettage of the nonunion, intertrochanteric valgus osteotomy, and revision internal fixation. In addition, valgus osteotomy will convert the shear forces across the nonunion to compression, aiding in healing of the nonunion. None of the other procedures addresses both issues, and hip fusion is inappropriate under these conditions. Lam SF: Fractures of the neck of the femur in children. J Bone Joint Surg Am 1971;53:1165-1179.

Question 13

A 22-month-old child has scrapes and bruises on his head and a severe deformity of the forearm after being thrown from a car as an unrestrained passenger in a motor vehicle accident. Examination reveals a Glasgow Coma Scale score of 12. Prior to treatment of the forearm, management should include

Explanation

As CT scanning has become available, the use of radiographs of the skull has decreased in importance for evaluation of head trauma. The indications for CT scanning for suspected head trauma include any degree of obtundation, focal neurologic deficit, history of a high-velocity injury, amnesia for the injury, progressive headache, persistent vomiting, children younger than age 2 years, serious facial injury, posttraumatic seizure, skull penetration, or a Glasgow Coma Scale score of 13 or less. Evidence of improved outcome with use of steroids in head trauma is lacking. Steroids are useful for increased intracranial pressure caused by brain tumors or abscesses. High-dose IV methylprednisolone is indicated for spinal cord trauma and improves the ultimate degree of recovery of function. When herniation is suspected in a patient with asymmetric neurologic findings or the patient's condition is deteriorating rapidly, a mannitol infusion may be used. Hall DE: Head injuries, in Hoekelman RA (ed): Primary Pediatric Care. St Louis, Mo, Mosby, 1997, pp 1709-1712. Nelson WE, Behrman RE, Kliegman RM (eds): Nelson Essentials of Pediatrics. Philadelphia, Pa, WB Saunders, 1998, p 712.

Question 14

Examination of a 5-year-old boy with amyoplasia shows a flexion contracture of 70 degrees of the right knee. The active arc of motion is from 70 degrees to 90 degrees, and the opposite knee has a flexion contracture of 10 degrees. Both hips are dislocated with flexion contractures of 10 degrees, passive hip motion is from 10 degrees to 90 degrees of flexion, and the feet are plantigrade and easily braceable. Despite a daily stretching program, the parents and physical therapists note that it is increasingly difficult for him to walk because of the flexion contracture of the right knee. Management of the knee flexion contracture should now include

Explanation

Most children with amyoplasia are ambulatory and when a decrease in function occurs because of a severe contracture, it must be addressed. A radical posterior soft-tissue release, including the posterior knee capsule and often the collateral ligaments and the posterior cruciate ligament, is needed to obtain extension. After the age of 1 year, aggressive physical therapy will do little to correct a contracture. Botulinum toxin A is indicated for spasticity and is contraindicated with severe contractures. Supracondylar femoral extension osteotomy works well, but will remodel at an average rate of 1 degree per month, which is not considered ideal in a young patient. Gradual correction with a circular ring external fixator is an option, but a soft-tissue release will also most likely be needed for a contracture of this severity. Sarwark JF, MacEwen GD, Scott CI Jr: Amyoplasia (a common form of arthrogryposis). J Bone Joint Surg Am 1990;72:465-469. DelBello DA, Watts HG: Distal femoral extension osteotomy for knee flexion contracture in patients with arthrogryposis. J Pediatr Orthop 1996;16:122-126.

Question 15

A 13-year-old girl who is 2 years postmenarche has been referred for management of scoliosis. She denies any history of back pain. Radiographs show a right thoracic curve of 35 degrees. She has a Risser sign of 4 and a bone age of 15.5 years. Management should consist of

Explanation

Because the patient is skeletally mature with a curve of less than 40 degrees, there is no benefit to bracing and surgery is not indicated. Management should consist of observation and follow-up radiographs in 6 months. Lonstein JE, Carlson JM: The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg Am 1984;66:1061-1071.

Question 16

In children with isolated zone II lacerations of the flexor tendon, poor digital motion is best correlated with

Explanation

In a recent study on restoration of motion following zone I and zone II flexor tendon repairs in children, age was found to have no effect on the results of zone II tendon repairs. Early passive motion offered no better results than immobilization for 3 weeks. Immobilization for more than 4 weeks correlated with poorer results.

Question 17

In a longitudinal study of children with spastic diplegia, analysis of long-term function will most likely reveal

Explanation

In a longitudinal study of 18 patients with spastic diplegia over a period of 32 months, three-dimensional gait analysis revealed a deterioration of gait stability with increases in double support time and decreases in single support time. Kinematic data also identified a loss of excursion about the knee, ankle, and pelvis. Interestingly, the static examination of the children showed a decrease in the popliteal angle over time. The authors concluded that ambulatory ability tends to worsen over time in children with spastic diplegia.

Question 18

Examination of a 7-year-old girl with myelomeningocele reveals calcaneal deformities of both feet. She ambulates on both extremities wearing ankle-foot orthoses and has no upper extremity aids. She has grade 5/5 motor strength to the tibialis anterior muscles and absent motor strength to the triceps surae. There is no varus or valgus deformity of the hindfoot, and the skin over the heels is intact; however, mild callosities are present. Management should consist of

Explanation

A calcaneal deformity of the foot may occur in children who have low lumbar myelomeningocele. Strong dorsiflexors overcome a weak or absent gastrocnemius-soleus complex, leading to downward growth of the calcaneal apophysis. The deformity is usually progressive and does not respond to nonsurgical management. Most authorities recommend transfer of the tibialis anterior muscle through the interosseous membrane to the posterior aspect of the calcaneus. This procedure has been reported to be effective in limiting progression of the deformity. An extra-articular subtalar arthodesis, a treatment option for valgus deformity of the hindfoot, is not indicated. Similarly, Achilles tendon tenodesis to the fibula, an option for managing valgus of the ankle, is not indicated. Calcaneal osteotomy may be used in older children with severe calcaneal deformity. Stott NS, Zionts LE, Gronley JK, Perry J: Tibialis anterior transfer for calcaneal deformity: A postoperative gait analysis. J Pediatr Orthop 1996;16:792-798.

Question 19

Figure 24 shows the radiograph of a 4-year-old girl with spina bifida. Examination reveals an L3 motor level, excellent sitting and standing balance, and satisfactory range of motion at the hips. Management should consist of

Explanation

Children with spina bifida and bilateral symmetrical dislocation of the hips usually do not require treatment. A level pelvis and good range of motion of the hips are more important for ambulation than reduction of bilateral hip dislocations. Because the patient has good sitting and standing balance and good range of motion, maintenance of that range of motion and symmetry is more important than reduction. Surgery is not recommended.

Question 20

Posterior spinal fusion for scoliosis should be performed on a patient with Duchenne muscular dystrophy when

Explanation

Progressive scoliosis develops in most patients with Duchenne muscular dystrophy. The onset of spinal deformity typically follows the cessation of walking, and curves can be expected to progress about 10 degrees per year. Posterior spinal fusion with instrumentation should be performed as soon as a curve of 25 degrees or greater is documented and before deterioration of pulmonary function (a FVC of less than 30%) precludes surgery. Patients with kyphotic posture tend to progress more rapidly than those with lordotic posture. Brace treatment is contraindicated because it is not definitive and it may mask curve progression while pulmonary function is concomitantly worsening. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 635-651.

Question 21

Figures 25a and 25b show the radiograph and MRI scan of a 7 1/2-year-old boy who has been limping for 1 year. His pain has worsened over the past 2 weeks, and his parents note swelling over the dorsum of the foot for the past 4 days. Examination reveals no fever, and laboratory studies show a WBC of 6,700/mm3, an erythrocyte sedimentation rate of 26 mm/h, and a normal C-reactive protein level. What is the most likely diagnosis?

Explanation

25b The diagnosis of tuberculous osteomyelitis in children is often delayed. In one series of 23 children, the average interval between the onset of symptoms and definite diagnosis was 4.3 months. In these patients, the presenting signs and symptoms were found to be mild, with the most common signs being localized swelling (69.6%) and a painful disability of the involved limbs (65.2%). A mild elevation of the erythrocyte sedimentation rate may be present, but the C-reactive protein level is usually normal. In patients who have osteoarticular tuberculosis, an MRI scan generally shows large intra-articular effusions, periarticular osteoporosis, and gross thickening of the synovial membrane. Differential diagnosis between tuberculosis and pyogenic arthritis is difficult, and an accurate diagnosis usually requires biopsy of synovial tissue. Aspiration of synovial fluid often results in insufficient information to make a diagnosis. Treatment generally consists of surgical debridement and combined antituberculous chemotherapy with isoniazid, ethambutol, and rifampin. Wang MN, Chen WM, Lee KS, Chin LS, Lo WH: Tuberculous osteomyelitis in young children. J Pediatr Orthop 1999;19:151-155.

Question 22

A 10-year-old boy who plays baseball reports acute pain after throwing a softball from the outfield to second base. A radiograph is shown in Figure 26. Management should consist of

Explanation

The patient has a fracture through a unicameral bone cyst, as evidenced by the "falling leaf" sign on the radiograph. Following healing of the fracture, treatment should consist of corticosteroid injection or bone marrow injection. Some cysts heal with the fracture and do not require injections. Biopsy is unnecessary because the radiograph shows that the cyst is benign. Curettage and bone grafting are seldom necessary because these cysts regularly heal with injections. Corticosteroids are useful when injected into the cyst, but are not used systemically. Pulsed electromagnetic fields have not been used therapeutically in this condition.

Question 23

The mother of an otherwise healthy 1-month-old infant reports that he is not moving his left leg after falling from his high chair 2 days ago. He has a temperature of 99.5 degrees F (37.5 degrees C). Examination reveals that the left thigh is moderately tender to palpation. Because the infant is apprehensive, range of motion is difficult to quantify, but appears to be normal at the hips and ankles. Range of motion of the left knee is approximately 25 degrees to 90 degrees. A radiograph of the leg is shown in Figure 27. Management should consist of

Explanation

The patient has a bucket-handle fracture of the distal femur with bilateral corner fractures of the distal femur and a transverse fracture of the proximal tibia. These fractures are virtually pathognomonic of child abuse. The infant should be admitted to the hospital, and child protection services should be notified for investigation of possible abuse. A skeletal survey should be obtained, along with laboratory studies that include a CBC, a platelet count, a prothrombin time, a partial thromboplastin time, and a bleeding time. Akbarnia BA: The role of the orthopaedic surgeon in child abuse, in Morrissy RT, Weinstein SL (eds): Lovell & Winter's Pediatric Orthopaedics, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 1315-1334.

Question 24

A 12-year-old girl with juvenile rheumatoid arthritis (JRA) has had chronic pain and synovitis about the knee that is now well-controlled medically. Examination reveals 20 degrees of valgus at the knee. Knee range of motion shows 10 degrees to 90 degrees of flexion. Treatment should consist of

Explanation

Children with JRA frequently have valgus in association with hypervascularity because of chronic inflammation. This is normally caused by overgrowth of the medial femoral epiphysis. Staple hemiepiphyseodesis, if done early, can reverse the deformity. Osteotomy is usually unnecessary at this age, and there is a risk of stiffness of the knee following the procedure. Synovectomy may be helpful but will not prevent or correct a deformity.

Question 25

Figure 28 shows the radiograph of a 6-year-old girl who has a right thoracic scoliosis that measures 60 degrees. Examination shows multiple cafe-au-lait spots, and family history reveals that the child's mother has the same disorder. The gene responsible for this disorder codes for

Explanation

The patient has the dystrophic type of scoliosis seen in patients with neurofibromatosis type I (NF-1). The NF-1 gene is located on chromosome 17 and codes for neurofibromin, believed to be a tumor-suppresser gene. Abnormalities in the dystrophin gene are seen in Duchenne muscular dystrophy and Becker muscular dystrophy. A mutation in the frataxin gene is responsible for Friedreich ataxia. The most common type of hereditary motor and sensory neuropathy (Charcot-Marie-Tooth), HMSN type IA is caused by a complete duplication of the peripheral myelin protein gene. A defect in the cellular sulfate transport protein results in undersulfation of proteoglycans seen in diastrophic dysplasia.

Question 26

A 12-year-old obese boy presents with sudden severe left groin pain and inability to bear weight after a minor fall. Radiographs show a severe left slipped capital femoral epiphysis. He is treated with urgent open reduction and internal fixation via a surgical hip dislocation approach to decompress the intracapsular hematoma. Which of the following is the most likely complication of this injury?

Explanation

Unstable SCFE (inability to bear weight) has a much higher rate of osteonecrosis compared to stable SCFE. Urgent decompression and anatomic reduction may help minimize this risk, but AVN remains the most devastating complication.

Question 27

A 6-week-old female infant is treated with a Pavlik harness for a dislocated left hip (Graf Type IV). After 3 weeks of strict harness wear, ultrasound shows the hip remains persistently dislocated. What is the most appropriate next step in management?

Explanation

Continued use of a Pavlik harness for a persistently dislocated hip beyond 3 to 4 weeks risks posterior acetabular wear (Pavlik harness disease). The next step is abandonment of the harness and progression to closed reduction and spica casting.

Question 28

A 5-year-old boy falls from monkey bars and sustains a widely displaced extension-type supracondylar humerus fracture. On presentation, his hand is pink and warm, but the radial pulse is absent. After prompt closed reduction and percutaneous pinning, the hand remains pink and warm, but the radial pulse is still absent. Doppler signal is present in the radial artery. Management should consist of:

Explanation

In a pink, pulseless hand following reduction of a supracondylar humerus fracture, observation is the standard of care as collateral circulation is adequate. Vascular exploration is indicated if the hand is white and pulseless after reduction.

Question 29

A 14-year-old boy sustains a Type III tibial tubercle avulsion fracture while playing basketball. He undergoes open reduction and internal fixation. Twelve hours postoperatively, he complains of unremitting leg pain disproportionate to the injury and pain with passive toe extension. What is the most critical next step?

Explanation

Tibial tubercle avulsion fractures have a well-documented association with anterior compartment syndrome due to disruption of the anterior tibial recurrent artery. Severe, unremitting pain and pain on passive stretch are hallmark signs requiring emergent fasciotomy.

Question 30

A 4-year-old boy who was treated for a right idiopathic clubfoot with the Ponseti method presents with a recurrent deformity. Examination reveals active supination of the foot during the swing phase of gait and dynamic forefoot adductus. Ankle dorsiflexion is 10 degrees. What is the most appropriate treatment?

Explanation

Dynamic supination in a relapsed clubfoot treated with the Ponseti method is best managed with a split anterior tibial tendon (STATT) transfer or full anterior tibial tendon transfer to the lateral cuneiform, provided the foot is passively correctable.

Question 31

A 14-year-old girl with adolescent idiopathic scoliosis presents with a right thoracic curve of 55 degrees and a left lumbar curve of 35 degrees. On bending films, the lumbar curve reduces to 15 degrees. The apical vertebral translation of the thoracic curve is 4 cm and the lumbar curve is 1 cm. What is the correct Lenke classification curve type for this patient?

Explanation

Lenke Type 1 curves have a structural main thoracic curve and a nonstructural lumbar curve. A lumbar curve that bends out to 25 degrees or less is considered nonstructural.

Question 32

A 4-year-old boy with spastic diplegic cerebral palsy (GMFCS Level IV) is evaluated for hip surveillance. He has bilateral hip flexion and adductor contractures. Anteroposterior pelvis radiograph shows a migration percentage of 45% bilaterally. What is the most appropriate management?

Explanation

In GMFCS level IV/V children with a migration percentage >40%, reconstructive surgery including VDRO and often a pelvic osteotomy is indicated to prevent hip dislocation. Soft tissue releases alone are insufficient for migration of this severity.

Question 33

A 2-month-old infant is undergoing treatment for right-sided idiopathic clubfoot using the Ponseti method. After four casts, the foot is fully abducted, but there is residual equinus of the ankle. During the planned percutaneous Achilles tenotomy, the surgeon must be careful to avoid injuring which of the following structures located immediately anterior and lateral to the tendon?

Explanation

The sural nerve and lesser saphenous vein lie directly lateral and anterior to the Achilles tendon. They are at risk during percutaneous tenotomy if the scalpel blade is directed laterally.

Question 34

A 6-year-old girl sustains a severely displaced extension-type supracondylar humerus fracture. On presentation, her hand is pink but the radial pulse is absent. After closed reduction and percutaneous pinning, the fracture is anatomically aligned, the hand remains pink and warm, but the radial pulse remains impalpable by Doppler. What is the most appropriate next step in management?

Explanation

A "pulseless, pink" hand after anatomic reduction of a supracondylar fracture is typically managed with observation. Collateral circulation is sufficient, and the pulse often returns within a few days; exploration is only indicated if the hand becomes poorly perfused.

Question 35

A 7-year-old boy presents with progressive valgus deformity of his left elbow and paresthesias in his ring and small fingers. He sustained an elbow fracture at age 3 that was treated nonoperatively. Radiographs show a nonunion of the lateral condyle. Which of the following is the most likely cause of his current neurologic symptoms?

Explanation

Nonunion of a pediatric lateral condyle fracture leads to a progressive cubitus valgus deformity. Over time, this valgus drift stretches the ulnar nerve, resulting in a tardy ulnar nerve palsy.

Question 36

An 18-month-old girl is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra at T8. The parents note no other medical history. What is the most important initial screening study for this patient?

Explanation

Congenital scoliosis has a high association with VACTERL anomalies, particularly renal (up to 30%) and intraspinal abnormalities (20-40%). A renal ultrasound and whole spine MRI are essential to rule out these concomitant issues.

Question 37

A 13-year-old obese boy presents with 2 weeks of worsening left hip pain and an inability to bear weight. Radiographs reveal a severe slipped capital femoral epiphysis (SCFE). He cannot ambulate even with crutches. Which of the following management strategies carries the highest risk of avascular necrosis (AVN) in this patient?

Explanation

Forceful closed reduction of an unstable SCFE significantly increases the risk of AVN. It disrupts the vulnerable, stretched retinacular vessels supplying the femoral head.

Question 38

A 6-month-old infant with achondroplasia is brought to the clinic due to episodes of central apnea, hyperreflexia, and profound hypotonia. Which of the following is the most appropriate diagnostic test to evaluate the underlying cause of these symptoms?

Explanation

Infants with achondroplasia are at risk for foramen magnum stenosis, which causes cervicomedullary compression leading to central apnea, myelopathy, and sudden death. MRI of the craniocervical junction is the gold standard for evaluation.

Question 39

A 3-year-old girl is evaluated for severe bilateral genu varum. Standing radiographs demonstrate medial tibial metaphyseal beaking, a metaphyseal-diaphyseal angle of 18 degrees, and depression of the medial physis. What is the most appropriate initial treatment for this patient?

Explanation

The patient has infantile Blount disease (Langenskiold stage II). In a symptomatic child under 4 years of age with progressive changes, KAFOs are the initial nonoperative treatment of choice.

Question 40

A 14-year-old boy presents with rigid flat feet and recurrent lateral ankle sprains. Examination reveals a lack of subtalar motion. Radiographs show a "C sign" on the lateral view. Which of the following represents the most likely anatomical location of the primary pathology?

Explanation

The "C sign" on a lateral radiograph is highly indicative of a talocalcaneal coalition. This coalition most commonly involves the middle facet of the subtalar joint.

Question 41

A 4-year-old boy previously treated with the Ponseti method for a right idiopathic clubfoot presents with dynamic supination of the foot during the swing phase of gait. Passive range of motion is normal. What is the most appropriate surgical intervention?

Explanation

Dynamic supination during the swing phase is a classic sign of clubfoot relapse caused by an overpowering tibialis anterior. It is treated with a complete anterior tibial tendon transfer (ATTT) to the lateral cuneiform.

Question 42

A 9-year-old girl with a history of right femoral shaft fracture treated non-operatively now has a 3 cm leg length discrepancy. According to the multiplier method, which of the following data points is strictly required to predict her discrepancy at skeletal maturity?

Explanation

The Paley multiplier method simplifies the prediction of leg length discrepancy at skeletal maturity. It uniquely requires only the child's current chronologic age, gender, and current leg length discrepancy.

Question 43

An 8-week-old female infant is being treated with a Pavlik harness for developmental dysplasia of the left hip. At her 2-week follow-up, the mother reports the infant is no longer kicking her left leg. On examination, the knee lacks active extension, but ankle and toe movements are normal. What is the most likely cause of this complication?

Explanation

Femoral nerve palsy in a Pavlik harness is typically caused by excessive hip flexion pressing the nerve against the pelvis. The treatment is temporary adjustment or removal of the harness, and the palsy usually resolves spontaneously.

Question 44

A 5-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. He is unable to flex the IP joint of his thumb and the DIP joint of his index finger. Which of the following nerve structures is most likely injured?

Explanation

The AIN is the most commonly injured nerve in extension-type supracondylar fractures. It presents with the inability to form an "OK" sign due to weakness of the FPL and FDP to the index finger.

Question 45

A 13-year-old obese boy presents with acute on chronic left groin pain and an inability to bear weight. Radiographs confirm a severe, unstable slipped capital femoral epiphysis (SCFE). Which of the following complications is most significantly increased in this patient compared to a stable SCFE?

Explanation

Unstable SCFE (defined by the inability to bear weight) carries a much higher risk of avascular necrosis (up to 50%) compared to stable SCFE. Urgent decompression and fixation can help mitigate this risk.

Question 46

An infant is born with bilateral idiopathic clubfeet. During the Ponseti casting technique, which of the following represents the correct sequence of deformity correction?

Explanation

The Ponseti method corrects deformities in the specific order of CAVE: Cavus, Adduction, Varus, and finally Equinus. The first step involves elevating the first ray to correct the forefoot cavus.

Question 47

A 2-month-old girl is being treated for developmental dysplasia of the hip with a Pavlik harness. At her 2-week follow-up, she exhibits decreased active knee extension on the right side. The harness is noted to be holding the hips in 120 degrees of flexion. What is the most appropriate next step in management?

Explanation

The infant has developed a femoral nerve palsy secondary to excessive hyperflexion in the Pavlik harness. The anterior straps should be loosened immediately to reduce hip flexion, which usually allows for full resolution.

Question 48

A 7-year-old boy with spastic diplegic cerebral palsy ambulates with a crouch gait. He has dynamic knee flexion contractures but no fixed bony deformities. Which of the following surgical interventions is contraindicated as an isolated procedure, as it may exacerbate his crouch gait?

Explanation

Isolated lengthening of the Achilles tendon in a patient with crouch gait will weaken plantar flexion. This leads to increased forward tibial advancement and severe exacerbation of the crouch deformity.

Question 49

A 10-month-old boy presents with anterolateral bowing of his left tibia. Radiographs reveal diaphyseal sclerosis and a narrow medullary canal. Which of the following systemic conditions is most closely associated with this clinical presentation?

Explanation

Anterolateral bowing of the tibia is the hallmark precursor to congenital pseudarthrosis of the tibia. This condition is highly associated with Neurofibromatosis type 1 (NF1).

Question 50

A 6-year-old boy presents with a displaced lateral condyle fracture of the humerus (Milch Type II). Open reduction and internal fixation is performed. Which of the following long-term complications is most characteristic if this fracture initially went unrecognized and progressed to nonunion?

Explanation

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

Question 51

A 14-year-old boy with a history of recurrent ankle sprains complains of deep, aching lateral hindfoot pain. On examination, he has rigid subtalar motion and pes planovalgus. Radiographs demonstrate a "C-sign" on the lateral view. Which of the following is the most likely diagnosis?

Explanation

A rigid flatfoot with a "C-sign" on lateral ankle radiographs indicates a talocalcaneal coalition. The C-sign represents the continuous bony outline bridging the medial talar dome and the sustentaculum tali.

Question 52

A 3-year-old girl is brought to the emergency department for a limp. She has a temperature of 38.8°C, an ESR of 45 mm/hr, and a WBC count of 13,000/mm³. She refuses to bear weight on her right leg. According to the Kocher criteria, what is the approximate probability that she has septic arthritis of the hip?

Explanation

This patient has all four Kocher predictors: fever >38.5°C, non-weight bearing, ESR >40, and WBC >12,000. The presence of all four criteria yields a 93% to 99% probability of septic arthritis.

Question 53

A 2-year-old boy is evaluated for genu varum. Standing radiographs demonstrate a metaphyseal-diaphyseal angle (Drennan angle) of 18 degrees on the right tibia. What is the most likely diagnosis?

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees strongly suggests infantile Blount disease. Angles less than 10 degrees are typical of physiologic bowing.

Question 54

An infant presents at 6 weeks of age with a right-sided neck mass. Her head is tilted to the right and her chin is rotated to the left. She has limited passive cervical range of motion. Which of the following screening tests should be routinely ordered for this condition?

Explanation

This infant has congenital muscular torticollis (CMT). Because up to 20% of infants with CMT have coexisting developmental dysplasia of the hip (DDH), a screening hip ultrasound is highly recommended.

Question 55

A 14-year-old girl sustains an ankle injury while sliding into a base. Radiographs reveal a Salter-Harris type III fracture of the anterolateral distal tibial epiphysis. What is the primary deforming force causing this specific fracture?

Explanation

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

Question 56

A 6-year-old boy is diagnosed with Legg-Calvé-Perthes disease. During the fragmentation stage, his anteroposterior radiograph demonstrates that the lateral aspect of the capital femoral epiphysis has maintained 40% of its original height. According to the Herring lateral pillar classification, what is his grade?

Explanation

In the Herring lateral pillar classification, Group C is defined by the lateral pillar maintaining less than 50% of its original height. Group B maintains >50%, and Group A has no lateral pillar involvement.

Question 57

A 14-year-old boy with a BMI of 38 presents with left hip pain and an antalgic gait for 6 weeks. Radiographs show a mild slipped capital femoral epiphysis. He undergoes uncomplicated in situ pinning. Three years later, he presents with groin pain exacerbated by hip flexion and internal rotation. What is the most likely cause of his current symptoms?

Explanation

Following in situ pinning of SCFE, the residual anterior metaphyseal prominence can lead to cam-type femoroacetabular impingement (FAI). This typically presents as groin pain with flexion and internal rotation due to abutment against the anterior acetabular rim.

Question 58

A 6-month-old girl with developmental dysplasia of the hip is taken to the operating room for a closed reduction and spica casting. An intraoperative arthrogram demonstrates a medial dye pool of 7 mm. What is the most appropriate next step in management?

Explanation

A medial dye pool greater than 5 mm on an arthrogram indicates an interposed soft tissue structure preventing a concentric reduction. Open reduction is indicated to clear obstructions such as an inverted limbus, pulvinar, or transverse acetabular ligament.

Question 59

A 9-year-old boy presents with a 4-month history of right hip pain and a painless limp. Radiographs reveal fragmentation of the right capital femoral epiphysis. The lateral pillar maintains 40% of its normal height. According to the Herring classification, what is the most appropriate treatment?

Explanation

This patient has Herring Group C (less than 50% lateral pillar height) Legg-Calvé-Perthes disease. In children older than 8 years of age with Group B or B/C borderline disease, surgical containment via proximal femoral osteotomy has been shown to yield better outcomes than nonoperative management.

Question 60

A 7-year-old boy is evaluated for a progressive deformity of his right elbow. He sustained a supracondylar humerus fracture 4 years ago that was treated with closed reduction and percutaneous pinning. Physical examination reveals a cubitus varus deformity of 15 degrees. If left untreated, what long-term complication is most uniquely associated with this specific deformity?

Explanation

Cubitus varus alters the mechanical axis, shifting the triceps line of pull medially. Over time, this repetitive stress causes chronic stretching of the lateral collateral ligament complex, leading to tardive posterolateral rotatory instability (PLRI) of the elbow.

Question 61

A 6-week-old female infant is undergoing treatment for developmental dysplasia of the left hip with a Pavlik harness. After 4 weeks of strict full-time harness wear, a follow-up ultrasound reveals that the left hip remains completely dislocated. What is the most appropriate next step?

Explanation

Continued use of a Pavlik harness in a persistently dislocated hip beyond 3 to 4 weeks significantly increases the risk of "Pavlik harness disease," which involves damage to the posterior acetabular wall. The harness should be discontinued, and the patient transitioned to a rigid orthosis or closed reduction.

Question 62

A 13-year-old obese boy presents with 3 weeks of vague groin pain and a limp. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). He undergoes in situ percutaneous pinning with a single screw. Which of the following screw positions carries the highest risk of accelerating chondrolysis?

Explanation

Screws placed in the anterosuperior quadrant of the femoral head frequently have unrecognized joint penetration, which is the leading cause of chondrolysis in SCFE pinning. The ideal position is center-center or slightly posteroinferior.

Question 63

A 3-year-old child who was successfully treated for idiopathic clubfoot using the Ponseti method presents with recurrent dynamic supination of the foot during the swing phase of gait. Passive range of motion reveals full dorsiflexion and neutral heel valgus. What is the most appropriate next step in management?

Explanation

Dynamic supination in a previously corrected clubfoot indicates a muscle imbalance. A full passive range of motion with dynamic supination is best treated with a tibialis anterior tendon transfer to the lateral cuneiform.

Question 64

A 6-year-old boy falls from monkey bars and sustains a Gartland type III supracondylar humerus fracture. On presentation, his hand is warm and pink, but the radial pulse is absent. After urgent closed reduction and percutaneous pinning, the hand remains pink and well-perfused, but the pulse is still absent by Doppler. What is the most appropriate next step?

Explanation

A "pulseless pink" hand after anatomic reduction and pinning of a supracondylar humerus fracture indicates adequate collateral perfusion. Observation is the standard of care, as the pulse often returns within 24 to 48 hours.

Question 65

A 4-year-old girl with spastic quadriplegic cerebral palsy (GMFCS level V) undergoes screening pelvis radiographs. Her migration percentage is calculated at 45% bilaterally. She has 30 degrees of hip abduction bilaterally with knees extended. What is the most appropriate intervention?

Explanation

In a child with CP and a migration percentage over 40%, soft tissue releases alone have an unacceptably high failure rate. Bony reconstruction with VDRO and possible pelvic osteotomy is the most reliable treatment to prevent further subluxation.

Question 66

A 6-week-old female infant is diagnosed with a dislocated but reducible left hip. She is placed in a Pavlik harness. After 3 weeks of compliant harness wear, ultrasound demonstrates the left hip remains dislocated. What is the most appropriate next step in management?

Explanation

Failure to reduce a dislocated hip after 3 to 4 weeks of Pavlik harness treatment requires discontinuation of the harness to prevent Pavlik harness disease. The next standard non-operative step is a rigid abduction orthosis, such as an Ilfeld or Rhino brace.

Question 67

A 2-year-old boy presents with a 3-day history of fever, irritability, and refusal to bear weight on his right leg. MRI reveals a subperiosteal abscess of the proximal femoral metaphysis with extension into the hip joint. What is the most likely mechanism of joint involvement?

Explanation

In the proximal femur, the metaphysis is intracapsular. Therefore, metaphyseal osteomyelitis can easily break through the cortex directly into the joint space, causing a concurrent septic arthritis.

Question 68

A 7-year-old boy is diagnosed with Legg-Calve-Perthes disease. Which of the following radiographic findings represents the classic "head-at-risk" sign described by Catterall?

Explanation

Catterall's "head-at-risk" signs include lateral subluxation, Gage's sign, metaphyseal cysts, and a horizontal physis. Lateral subluxation strongly predicts poor outcomes due to the risk of hinge abduction.

Question 69

A 10-month-old infant with homozygous achondroplasia presents with recent episodes of sleep apnea and delayed motor milestones. Examination shows exaggerated reflexes in the lower extremities. What is the best initial diagnostic study?

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis causing cervicomedullary compression, manifesting as central sleep apnea and hyperreflexia. Urgent MRI of the craniocervical junction is essential to evaluate the need for decompression.

Question 70

A 13-year-old boy sustains a twisting injury to his ankle. CT scan demonstrates a fracture pattern that is sagittal in the epiphysis, axial in the physis, and coronal in the metaphysis. Which direction of external force typically causes this specific fracture pattern?

Explanation

A triplane fracture typically occurs in adolescents due to an external rotation force. The asymmetric closure of the distal tibial physis (central, then anteromedial, then posteromedial, then lateral) dictates this classic multiplanar propagation.

Question 71

A 14-year-old girl with adolescent idiopathic scoliosis (AIS) has a right thoracic curve of 48 degrees and a Risser stage of 0. She has not reached menarche. What is the most appropriate recommendation?

Explanation

This patient has a curve approaching 50 degrees and has significant remaining growth potential (Risser 0, premenarchal). Surgery (posterior spinal fusion) is indicated for curves greater than 45-50 degrees to prevent continued progression into adulthood.

Question 72

An infant is born with Aitken Class C proximal focal femoral deficiency (PFFD) on the right. The acetabulum is severely dysplastic, the femoral head is absent, and there is a severe limb length discrepancy. What knee finding is most consistently associated with PFFD?

Explanation

PFFD is strongly associated with absence or hypoplasia of the cruciate ligaments, leading to anteroposterior knee instability. Fibular hemimelia is another extremely common concurrent finding.

Question 73

A 12-year-old boy presents with recurring ankle sprains and rigid flatfeet. CT scan confirms a large, symptomatic talocalcaneal coalition involving the middle facet, comprising 60% of the joint surface. Nonoperative management has failed. What is the most appropriate surgical treatment?

Explanation

For a talocalcaneal coalition involving greater than 50% of the posterior facet, isolated resection is associated with poor outcomes and recurrence. Subtalar arthrodesis is the most appropriate procedure to relieve pain and restore stability.

Question 74

A 3-year-old obese girl presents with progressive bilateral genu varum. Standing radiographs reveal a diaphyseal-metaphyseal angle (Drennan angle) of 22 degrees and medial metaphyseal beaking. What is the most appropriate initial treatment?

Explanation

Infantile Blount's disease in a child under 3-4 years with Langenskiold stage I or II is initially treated with orthotics (KAFOs) to offload the medial physis. Surgical intervention is reserved for older children, brace failure, or advanced stages.

Question 75

A 14-year-old girl sustains an isolated fracture of the anterolateral distal tibial epiphysis. Radiographs show 3 mm of displacement. What is the primary deforming force causing this specific fracture pattern?

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It is an avulsion fracture caused by the pull of the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury.

Question 76

A 15-year-old male gymnast complains of worsening low back pain with radicular symptoms into the L5 distribution. Radiographs reveal a high-grade (Meyerding Grade IV) L5-S1 isthmic spondylolisthesis. What is the most common neurologic complication following surgical reduction and instrumented fusion for this condition?

Explanation

The L5 nerve root is highly susceptible to stretch injury during the reduction of severe L5-S1 slips. Consequently, L5 radiculopathy is the most common neurologic complication associated with surgical treatment of high-grade spondylolisthesis.

Question 77

A 4-week-old female with a history of breech presentation is diagnosed with developmental dysplasia of the hip (DDH). Ultrasound shows an alpha angle of 45 degrees, a beta angle of 75 degrees, and 40% femoral head coverage. Treatment with a Pavlik harness is initiated. What is the most common iatrogenic nerve complication associated with this treatment?

Explanation

The most common nerve complication of a Pavlik harness is femoral nerve palsy, typically caused by excessive hyperflexion of the hips. It usually resolves completely after temporarily removing or adjusting the harness.

Question 78

A 13-year-old obese boy presents with 2 days of severe right hip pain after a minor fall and is completely unable to bear weight. Radiographs show a posterior and inferior slip of the proximal femoral epiphysis. What is the most appropriate management for this acute, unstable slipped capital femoral epiphysis (SCFE)?

Explanation

Unstable SCFE requires urgent in situ fixation, typically with a single screw, to decompress the joint capsule and stabilize the slip. Forceful closed reduction is contraindicated as it significantly increases the risk of avascular necrosis.

Question 79

A 7-year-old boy presents with a painless limp. Radiographs demonstrate fragmentation of the capital femoral epiphysis consistent with Legg-Calve-Perthes disease. According to the Herring lateral pillar classification, a hip that maintains 60% of its lateral pillar height is classified into which group, and what is the generally expected outcome?

Explanation

Group B involves maintenance of >50% lateral pillar height. Patients under 8 years of age at the onset of Group B LCPD generally have good outcomes with containment treatment, whereas older children may have less favorable results.

Question 80

A 3-month-old infant treated with the Ponseti method for idiopathic clubfoot has undergone five serial casts. The midfoot is now fully corrected and abducted to 70 degrees, but severe equinus persists. What is the next most appropriate step in management?

Explanation

Once the cavus, adductus, and varus deformities are fully corrected via serial casting in the Ponseti method, residual equinus is treated with a percutaneous Achilles tenotomy followed by a final cast for 3 weeks.

Question 81

A 5-year-old boy falls from the monkey bars and sustains a Gartland type III extension supracondylar humerus fracture. Examination shows weakness in flexing the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN), 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 82

A 14-year-old boy with a history of recurrent ankle sprains presents with rigid, painful flatfeet and peroneal spasticity. A CT scan of the hindfoot is ordered to evaluate for a tarsal coalition. If a talocalcaneal coalition is present, which facet is most commonly involved?

Explanation

The middle facet is the most commonly involved facet in talocalcaneal coalitions. It is best visualized on coronal CT scans of the hindfoot and is a frequent cause of rigid flatfoot in adolescents.

Question 83

A 13-year-old premenarchal female (Risser 0) presents with right thoracic adolescent idiopathic scoliosis. Standing radiographs reveal a Cobb angle of 32 degrees. What is the most appropriate recommended treatment?

Explanation

TLSO bracing is indicated for skeletally immature patients (Risser 0-2) with an AIS curve of 25 to 45 degrees. Bracing has been proven to significantly decrease the risk of curve progression to the surgical threshold.

Question 84

A 6-year-old boy with spastic quadriplegic cerebral palsy (GMFCS Level V) is evaluated during routine hip surveillance. He is currently pain-free, but AP pelvis radiographs reveal a bilateral migration percentage of 45%. What is the most appropriate management?

Explanation

In a spastic CP patient, a hip migration percentage >40% typically requires bony reconstruction, including VDRO and often a pelvic osteotomy (like a Dega), to provide stable joint coverage. Soft tissue releases alone have a high failure rate at this degree of subluxation.

Question 85

A 4-year-old boy presents with right hip pain, a temperature of 38.6 C (101.5 F), refusal to bear weight, an ESR of 45 mm/hr, and a WBC count of 13,000/mm3. According to the Kocher criteria, what is the predictive probability that this child has septic arthritis of the hip?

Explanation

The Kocher criteria include non-weight-bearing status, temperature > 38.5 C, ESR > 40 mm/hr, and WBC > 12,000/mm3. Having all 4 positive criteria correlates with a 99% probability of septic arthritis.

Question 86

A 4-year-old girl presents with progressive bilateral genu varum. Radiographs show Langenskiold stage III changes of the proximal medial tibia with a metaphyseal-diaphyseal angle of 18 degrees. What is the recommended treatment?

Explanation

In infantile Blount disease, children older than 3 years with advanced Langenskiold stages (II or III) and severe deformity require surgical correction via a proximal tibial valgus osteotomy. Bracing is generally ineffective after age 3.

Question 87

A 10-year-old boy falls while skiing and sustains a displaced Meyers and McKeever Type III tibial eminence fracture. Which of the following structures is most commonly entrapped in the fracture site, preventing closed reduction?

Explanation

The anterior horn of the lateral meniscus is the most common structure to become entrapped in a displaced tibial eminence fracture. This interposition often necessitates arthroscopic or open reduction.

Question 88

A 14-year-old boy twists his ankle while playing soccer. X-rays show a Salter-Harris III fracture of the anterolateral distal tibia (Tillaux fracture). This fracture pattern is primarily determined by which of the following mechanisms of distal tibial physeal closure?

Explanation

The distal tibial physis closes in a predictable sequence: central, then medial, and finally lateral. The open anterolateral physis remains vulnerable to avulsion by the anterior inferior tibiofibular ligament, resulting in a Tillaux fracture.

Question 89

A 4-year-old boy, weighing 18 kg (40 lbs), sustains an isolated closed midshaft femur fracture after falling from a slide. What is the gold standard treatment for this patient?

Explanation

For preschool children aged 6 months to 5 years (and weighing less than 20 kg), early spica casting is the standard of care for isolated closed midshaft femur fractures, yielding excellent clinical outcomes.

Question 90

A 2-year-old child presents with an anterolateral bow of the tibia and a pseudarthrosis visible on radiographs. This condition is most strongly associated with which of the following genetic disorders?

Explanation

Congenital pseudarthrosis of the tibia (CPT) is characterized by anterolateral bowing and has a strong clinical association with Neurofibromatosis Type 1 (NF1), which is present in over 50% of these patients.

Question 91

An 8-year-old girl presents with lateral knee pain and a painful snapping sensation in her left knee. MRI confirms a complete discoid lateral meniscus without a tear. She has mechanical symptoms that restrict sports participation. Management should consist of:

Explanation

Symptomatic discoid menisci with mechanical symptoms are treated with partial meniscectomy (saucerization) to create a more normal C-shaped meniscus. Total meniscectomy is avoided due to the high risk of early-onset osteoarthritis.

Question 92

A 6-month-old infant is diagnosed with idiopathic infantile scoliosis with a 25-degree left thoracic curve. The rib-vertebra angle difference (RVAD) of Mehta is measured at 30 degrees. What is the most appropriate initial management?

Explanation

An RVAD (Mehta angle) greater than 20 degrees is highly predictive of curve progression in infantile idiopathic scoliosis. Early serial casting (Mehta casting) is the gold standard for progressive curves to harness growth for potential correction.

Question 93

A 14-year-old male gymnast reports 6 weeks of localized low back pain that worsens with lumbar extension. Neurologic exam is normal. Oblique radiographs show a radiolucency at the pars interarticularis of L5, and a SPECT scan shows intense focal uptake. Initial management should consist of:

Explanation

Acute or stress-reactive spondylolysis (indicated by positive SPECT or MRI bone edema) is initially managed nonoperatively with activity modification, core stabilization therapy, and often an antilordotic brace until symptoms resolve.

Question 94

An 18-month-old child with achondroplasia presents with central sleep apnea, hyperreflexia, and delayed motor milestones. Which of the following is the most likely anatomic cause of these symptoms?

Explanation

Foramen magnum stenosis in achondroplasia can cause severe cervicomedullary compression, presenting clinically with central sleep apnea, myelopathy (hyperreflexia), and a risk of sudden death. It requires urgent neurosurgical evaluation for decompression.

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

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

Key Takeaway

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

Chapter Index