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Pediatric Hip MCQs

Practice Set 100 of 104

This practice set contains high-yield board review questions covering key concepts in Pediatric Hip. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1981

Topic: Pediatric Hip
A 14-year-old boy underwent in situ single-screw fixation for an unstable slipped capital femoral epiphysis (SCFE). Six months later, he complains of severe hip stiffness. Radiographs show a marked reduction in the joint space to <3 mm without femoral head collapse. What is the most likely diagnosis?
. Avascular necrosis (AVN)
. Chondrolysis
. Septic arthritis
. Femoroacetabular impingement
. Implant failure

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis presents with acute joint space narrowing and severe stiffness following a SCFE, often associated with unrecognized articular pin penetration. Unlike AVN, chondrolysis does not typically involve structural collapse of the femoral head.

Question 1982

Topic: Pediatric Hip

A 9-year-old boy with known Legg-Calve-Perthes disease presents with increasing hip pain and decreased range of motion. A dynamic hip arthrogram reveals hinge abduction, demonstrating the anterolateral femoral head impinging on the acetabular rim. What is the most appropriate surgical management?

. Adductor tenotomy and Petrie casting
. In situ pinning of the capital femoral epiphysis
. Varus derotational osteotomy of the proximal femur
. Valgus extension osteotomy of the proximal femur
. Core decompression of the femoral head

Correct Answer & Explanation

. Valgus extension osteotomy of the proximal femur

Explanation

Hinge abduction occurs when the enlarged, extruded anterolateral femoral head impinges against the lateral acetabular rim during abduction. A valgus-extension proximal femoral osteotomy is indicated to redirect the impinging segment away from the rim, improving congruency and relieving pain.

Question 1983

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute on chronic knee pain and an inability to bear weight. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant prognostic risk factor for the development of avascular necrosis (AVN) in this patient?

. Failure to perform a capsulotomy
. Time to surgery greater than 24 hours
. Concomitant obesity
. An unstable slip
. Bilateral involvement

Correct Answer & Explanation

. An unstable slip

Explanation

The most significant risk factor for AVN in slipped capital femoral epiphysis is an unstable slip, defined clinically by the patient's inability to bear weight. While timing of surgery and decompression are debated, instability remains the strongest predictor.

Question 1984

Topic: Pediatric Hip

A 12-year-old obese boy presents with a 3-week history of left groin pain and a limp. He is diagnosed with a stable left slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning. The parents ask about the risk to the right hip. Prophylactic pinning of the contralateral, asymptomatic hip is most strongly indicated in patients with which of the following characteristics?

. Age greater than 14 years at presentation
. Underlying endocrine disorder, such as hypothyroidism
. Body Mass Index (BMI) greater than the 95th percentile
. Presentation with an acute-on-chronic slip
. Slip angle greater than 50 degrees on the affected side

Correct Answer & Explanation

. Underlying endocrine disorder, such as hypothyroidism

Explanation

Correct Answer: Underlying endocrine disorder, such as hypothyroidismThe risk of developing a contralateral SCFE is approximately 20-40% overall. However, prophylactic pinning of the contralateral hip is generally reserved for patients at exceptionally high risk. Strong indications for prophylactic pinning include underlying endocrine disorders (e.g., hypothyroidism, growth hormone deficiency), renal osteodystrophy, previous radiation therapy to the pelvis, and very young age at presentation (typically less than 10 years old for boys). While obesity (high BMI) is a risk factor for SCFE, it alone is not an absolute indication for prophylactic pinning of the contralateral side. The severity of the initial slip or an acute-on-chronic presentation does not dictate contralateral prophylactic pinning.

Question 1985

Topic: Pediatric Hip
A 7-year-old boy presents with a painless limp of 2 months' duration. Radiographs of the pelvis demonstrate fragmentation and sclerosis of the right capital femoral epiphysis, consistent with Legg-Calvé-Perthes disease. Which of the following is considered the most important prognostic factor for the final radiographic outcome of the hip?
. Gender of the patient
. Age of the patient at the time of clinical onset
. Body mass index
. Presence of a metaphyseal cyst
. Degree of initial pain

Correct Answer & Explanation

. Age of the patient at the time of clinical onset

Explanation

In Legg-Calvé-Perthes disease, the age of the patient at the onset of the disease is the single most important prognostic factor. Children who develop the disease at a younger age (typically under 6 years) have a much better prognosis because they have more time for the femoral head to remodel before skeletal maturity. Patients who present at an older age (especially over 8 years) have a higher risk of developing a permanently deformed femoral head (coxa magna, coxa plana) and subsequent early-onset osteoarthritis. While lateral pillar involvement (Herring classification) is also a critical prognostic radiographic factor, age is the most important demographic/clinical factor.

Question 1986

Topic: Pediatric Hip

A 13-year-old boy presents with a stable left slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning. The parents inquire about the risk of the right hip developing a similar problem. Which of the following is the strongest radiographic predictor for the development of a contralateral slip?

. Posterior sloping angle greater than 15 degrees
. Open triradiate cartilage
. Klein's line intersecting less than 10% of the epiphysis
. Alpha angle greater than 55 degrees
. Metaphyseal blanch sign of Steel

Correct Answer & Explanation

. Open triradiate cartilage

Explanation

Correct Answer: BThe status of the triradiate cartilage is a strong radiographic predictor of future contralateral slip in patients presenting with a unilateral SCFE. An open triradiate cartilage indicates significant remaining skeletal growth and correlates with a high risk (up to 80% in some studies) of developing a contralateral SCFE. The modified Oxford bone age score is also used to assess this risk, heavily weighting the triradiate cartilage and iliac apophysis. Prophylactic pinning of the contralateral hip is often considered in patients with open triradiate cartilage, endocrine disorders, or an inability to follow up reliably. The posterior sloping angle and Klein's line are used to diagnose or quantify the severity of the current slip, not predict contralateral occurrence. The alpha angle is used to assess for femoroacetabular impingement (cam morphology), which can be a sequela of SCFE. The metaphyseal blanch sign of Steel is a radiographic sign of SCFE on an AP pelvis radiograph, representing the overlapping of the posteriorly displaced epiphysis and the metaphysis.

Question 1987

Topic: Pediatric Hip

A 4-week-old female is being treated with a Pavlik harness for a dislocated right hip. At her 2-week follow-up appointment, the parents report that she is not kicking her right leg as much as her left. On examination, she has absent active knee extension on the right, but normal active ankle and toe movements. What is the most likely cause of this finding?

. Obturator nerve palsy from excessive abduction
. Femoral nerve palsy from excessive hyperflexion
. Sciatic nerve palsy from excessive extension
. Avascular necrosis of the femoral head
. Transient synovitis of the hip

Correct Answer & Explanation

. Femoral nerve palsy from excessive hyperflexion

Explanation

Correct Answer: BThe clinical presentation of absent active knee extension with preserved distal motor function in an infant wearing a Pavlik harness is classic for a femoral nerve palsy. This complication is typically caused by excessive hyperflexion of the hip in the harness, which compresses the femoral nerve against the inguinal ligament or pelvic brim. The appropriate management is to temporarily remove the harness or adjust it to decrease the amount of flexion, allowing the nerve palsy to resolve, which it almost always does. Excessive abduction in a Pavlik harness is associated with avascular necrosis (AVN) of the femoral head, not an isolated obturator nerve palsy. Sciatic nerve palsy is not a typical complication of Pavlik harness treatment and would present with distal deficits (ankle/toe movement). Transient synovitis is a cause of hip pain in older children (typically 3-8 years) and does not cause isolated motor nerve palsies.

Question 1988

Topic: Pediatric Hip
An 8-year-old boy presents with a painless limp of 3 months duration. Radiographs show fragmentation of the capital femoral epiphysis with lateral subluxation, consistent with Legg-Calvé-Perthes disease. Which of the following is considered the most significant prognostic factor for the long-term outcome of the hip?
. Gender of the patient
. Age at clinical onset
. Presence of a metaphyseal cyst
. Degree of restricted internal rotation
. Body mass index

Correct Answer & Explanation

. Age at clinical onset

Explanation

The most significant prognostic factor for the long-term outcome in Legg-Calvé-Perthes disease is the age of the patient at the onset of the disease. Children who develop the disease before the age of 6 generally have a good prognosis because they have more time for the femoral head to remodel before skeletal maturity. Children over the age of 8 at onset have a significantly worse prognosis and a higher likelihood of developing early osteoarthritis, as there is less remaining growth for remodeling. The lateral pillar classification (Herring) is the most important radiographic prognostic factor, but age remains the most critical overall clinical factor. While restricted motion and metaphyseal cysts are part of the clinical picture, they do not supersede age in prognostic value.

Question 1989

Topic: Pediatric Hip

A 12-year-old obese boy presents with 3 weeks of left groin and knee pain. He walks with an antalgic, externally rotated gait. Radiographs confirm a mild, stable slipped capital femoral epiphysis (SCFE). He undergoes in situ single-screw fixation. Which of the following is the most significant risk factor for the development of chondrolysis in this patient?

. Unrecognized joint penetration by the screw
. Severe initial slip angle
. Concomitant prophylactic pinning of the contralateral hip
. Delay in surgical intervention greater than 24 hours
. Use of a fully threaded screw

Correct Answer & Explanation

. Unrecognized joint penetration by the screw

Explanation

Correct Answer: Unrecognized joint penetration by the screwChondrolysis is a devastating complication of SCFE characterized by the rapid destruction of articular cartilage, leading to a stiff, painful hip and joint space narrowing on radiographs. The most significant and well-documented risk factor for chondrolysis following surgical fixation of SCFE is unrecognized intra-articular hardware penetration. To prevent this, surgeons must utilize the "approach-withdraw" technique under fluoroscopy to ensure the screw has not breached the articular surface. While severe slip angle and unstable slips increase the risk of avascular necrosis (AVN), hardware penetration is the primary culprit for chondrolysis. Prophylactic pinning of the contralateral hip does not increase the risk of chondrolysis in the operative hip. Delay in surgery for a stable slip does not inherently cause chondrolysis, though it may allow the slip to progress.

Question 1990

Topic: Pediatric Hip

A 12-year-old obese male presents with left knee pain and an antalgic gait for 3 weeks. Examination reveals obligatory external rotation of the left hip with passive flexion. Radiographs confirm a mild, stable slipped capital femoral epiphysis (SCFE) of the left hip. The right hip is radiographically normal. Which of the following is the strongest indication for prophylactic in situ pinning of the contralateral (right) hip?

. A) Patient age of 12 years
. B) Male sex
. C) Body mass index > 95th percentile
. D) Initial slip angle > 30 degrees
. E) Presence of an underlying endocrine disorder

Correct Answer & Explanation

. E) Presence of an underlying endocrine disorder

Explanation

Correct Answer: EProphylactic pinning of the contralateral hip in SCFE is a topic of debate, but there are absolute and relative indications. The strongest indication for prophylactic pinning is the presence of an underlying endocrine disorder (e.g., hypothyroidism, renal osteodystrophy, panhypopituitarism) or prior radiation therapy. Patients with endocrine disorders have a bilateral involvement rate approaching 100%, compared to the 20-40% bilateral rate in idiopathic cases. Other relative indications for prophylactic pinning include an inability to follow up, young age at presentation (males < 12, females < 10), and open triradiate cartilage. While obesity (Option C) and young age (Option A) increase the risk of a contralateral slip, an endocrine disorder is the most definitive and strongest indication among the choices provided. Slip angle (Option D) and sex (Option B) are not primary determinants for prophylactic contralateral pinning.

Question 1991

Topic: Pediatric Hip

A 4-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the parents report that she is not kicking her left leg as much as her right. On physical examination, the infant lacks active knee extension on the left side, but exhibits normal ankle dorsiflexion and plantar flexion. What is the most likely cause of this physical examination finding?

. Excessive abduction of the hip in the harness
. Excessive flexion of the hip in the harness
. Excessive extension of the hip in the harness
. Inadequate flexion of the hip in the harness
. Excessive adduction of the hip in the harness

Correct Answer & Explanation

. Excessive flexion of the hip in the harness

Explanation

Correct Answer: Excessive flexion of the hip in the harnessThe patient is presenting with a femoral nerve palsy, which is a known complication of Pavlik harness treatment for DDH. Femoral nerve palsy presents as a loss of active knee extension and is caused by hyperflexion of the hip in the harness, which compresses the femoral nerve against the inguinal ligament. If this occurs, the harness should be temporarily removed or adjusted to decrease the amount of hip flexion until nerve function returns. Excessive abduction of the hip (Option A) is associated with avascular necrosis (AVN) of the femoral head, not femoral nerve palsy. Inadequate flexion (Option D) or excessive adduction (Option E) would lead to failure of reduction or posterior dislocation of the hip, rather than a nerve palsy.

Question 1992

Topic: Pediatric Hip

A 12-year-old obese male presents with a 3-week history of left groin pain and an antalgic gait. Radiographs confirm a mild, stable slipped capital femoral epiphysis (SCFE) on the left. The right hip is radiographically normal and asymptomatic. Which of the following patient factors represents the strongest indication for prophylactic in situ pinning of the contralateral (right) hip?

. Patient age of 12 years
. Body Mass Index (BMI) > 95th percentile
. Presence of primary hypothyroidism
. Slip angle of 45 degrees on the affected side
. Male sex

Correct Answer & Explanation

. Presence of primary hypothyroidism

Explanation

Correct Answer: Presence of primary hypothyroidismProphylactic pinning of the contralateral hip in SCFE is a debated topic, but there are clear absolute and relative indications. The strongest indication for prophylactic pinning is the presence of an underlying endocrine disorder, such as hypothyroidism, panhypopituitarism, or renal osteodystrophy, as these patients have a significantly higher risk (up to 100% in some studies) of developing a contralateral slip. Other indications include patients undergoing radiation therapy, and chronologic age less than 10 years (or open triradiate cartilage). While obesity (Option B) and male sex (Option E) are risk factors for SCFE in general, they are not absolute indications for prophylactic pinning on their own. The severity of the slip on the affected side (Option D) does not dictate the need for contralateral prophylaxis.

Question 1993

Topic: Pediatric Hip
An 8-year-old boy presents with a painless limp of 4 months' duration. Radiographs reveal fragmentation of the capital femoral epiphysis. Which of the following is considered the most important prognostic factor for long-term hip survival and the development of osteoarthritis in a patient with Legg-Calvé-Perthes disease?
. Age at the onset of disease
. Patient gender
. Body Mass Index (BMI)
. Degree of initial pain
. Presence of a positive Trendelenburg sign

Correct Answer & Explanation

. Age at the onset of disease

Explanation

Legg-Calvé-Perthes disease is an idiopathic avascular necrosis of the proximal femoral epiphysis in children. The two most critical prognostic factors for long-term outcomes (i.e., development of premature osteoarthritis and sphericity of the femoral head at skeletal maturity) are the age of the patient at the onset of the disease and the extent of epiphyseal involvement (often measured by the Herring Lateral Pillar classification). Children who develop the disease before age 6 generally have a good prognosis regardless of treatment because they have more time for remodeling. Children over the age of 8 have a worse prognosis and are more likely to benefit from surgical containment (e.g., femoral or pelvic osteotomy) if they fall into Herring Lateral Pillar group B or B/C. Gender, BMI, and initial pain are not the primary determinants of long-term joint survival.

Question 1994

Topic: Pediatric Hip

A 13-year-old boy undergoes in situ single-screw fixation for a stable slipped capital femoral epiphysis (SCFE). Six months postoperatively, he returns to the clinic complaining of severe hip stiffness and pain with any range of motion. On physical examination, he has a 15-degree flexion contracture and global restriction of hip motion. Radiographs demonstrate concentric joint space narrowing of the affected hip without evidence of hardware penetration into the joint. What is the most likely diagnosis?

. Avascular necrosis of the femoral head
. Chondrolysis
. Septic arthritis
. Unrecognized hardware penetration
. Cam-type femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Correct Answer: ChondrolysisChondrolysis is a devastating complication of SCFE characterized by the rapid, progressive loss of articular cartilage. It presents clinically with severe global stiffness, pain, and flexion contractures. Radiographically, it is identified by concentric joint space narrowing (typically defined as a joint space < 3 mm). While unrecognized hardware penetration is a known cause of chondrolysis, the vignette explicitly states there is no evidence of hardware penetration, meaning this is idiopathic chondrolysis associated with the SCFE itself. Avascular necrosis (Option A) typically presents with segmental collapse and sclerosis of the femoral head, not isolated concentric joint space narrowing. Septic arthritis (Option C) would present more acutely with systemic signs of infection. Cam impingement (Option E) causes activity-related groin pain and restricted internal rotation, but not global stiffness and concentric joint space loss.

Question 1995

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department with hip pain. According to the Loder classification, which of the following criteria definitively distinguishes an unstable slipped capital femoral epiphysis (SCFE) from a stable SCFE?

. Duration of symptoms greater than 3 weeks
. Southwick slip angle greater than 50 degrees
. Ability to bear weight with or without crutches
. Presence of a joint effusion on ultrasound
. Degree of posterior tilt on the cross-table lateral radiograph

Correct Answer & Explanation

. Ability to bear weight with or without crutches

Explanation

The Loder classification defines an unstable SCFE purely clinically based on the patient's inability to bear weight, even with assistive devices. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 47%).

Question 1996

Topic: Pediatric Hip

An 18-month-old girl presents with a painless waddling gait. Pelvic radiographs demonstrate a completely dislocated left hip, a broken Shenton line, and an acetabular index of 42 degrees. What is the most appropriate definitive management?

. Closed reduction and application of a spica cast
. Application of a Pavlik harness
. Open reduction, capsulorrhaphy, and pelvic osteotomy
. Open reduction alone
. Observation until age 4 for skeletal maturity

Correct Answer & Explanation

. Open reduction, capsulorrhaphy, and pelvic osteotomy

Explanation

In walking-age children (over 18 months) with untreated developmental dysplasia of the hip (DDH), closed reduction often fails. Open reduction combined with a pelvic osteotomy (like a Pemberton or Salter) is indicated to address the significant secondary acetabular dysplasia.

Question 1997

Topic: Pediatric Hip

A 9-year-old boy is diagnosed with Legg-Calve-Perthes disease. Radiographs reveal collapse of the lateral pillar, maintaining only 40% of its original height. Based on the Herring lateral pillar classification, what is his group and optimal management?

. Group B, conservative management
. Group B, surgical containment
. Group C, surgical containment
. Group C, conservative management
. Group A, surgical containment

Correct Answer & Explanation

. Group C, surgical containment

Explanation

A lateral pillar maintaining less than 50% of its original height is classified as Herring Group C. In children over 8 years old, outcomes are generally poor regardless of treatment, but some evidence supports surgical containment for borderline B/C or C hips in older children to optimize sphericity.

Question 1998

Topic: Pediatric Hip

A 14-year-old boy presents to the emergency department unable to bear weight on his left leg after a minor fall. Radiographs show a severe left slipped capital femoral epiphysis (SCFE). He is diagnosed with an unstable SCFE. Which of the following is the most significant complication specific to this diagnosis compared to a stable SCFE?

. Chondrolysis
. Osteonecrosis of the femoral head
. Femoroacetabular impingement
. Contralateral slip
. Premature physeal closure

Correct Answer & Explanation

. Osteonecrosis of the femoral head

Explanation

Unstable SCFE, defined by the inability to bear weight even with crutches, carries a high risk of osteonecrosis (avascular necrosis) of the femoral head, with rates up to 50%. Stable SCFE has a very low risk of osteonecrosis in comparison.

Question 1999

Topic: Pediatric Hip
A 9-year-old boy presents with a 4-month history of a painless limp. Radiographs demonstrate fragmentation of the right capital femoral epiphysis with >50% lateral pillar involvement. According to the Herring lateral pillar classification, what is his prognostic group and the recommended treatment approach?
. Group A; symptomatic treatment only
. Group B; symptomatic treatment only
. Group B; surgical containment
. Group C; surgical containment
. Group C; total hip arthroplasty

Correct Answer & Explanation

. Group C; surgical containment

Explanation

Greater than 50% loss of lateral pillar height categorizes the patient as Herring Group C, which generally portends a poorer prognosis in Legg-Calvé-Perthes disease. In children over the age of 8, surgical containment (such as a proximal femoral osteotomy) is often recommended to improve outcomes.

Question 2000

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs reveal fragmentation of the femoral head with the lateral pillar maintaining exactly 40% of its original height. According to the Herring lateral pillar classification, what is the most appropriate grade and the associated long-term prognosis for joint congruency if treated non-operatively?
. Group C; poor prognosis with a high risk of an aspherical femoral head and early osteoarthritis.
. Group A; minimal risk of aspherical femoral head.
. Group B; favorable prognosis if the patient is over 8 years old.
. Group B; predictable remodeling into a spherical head regardless of age.
. Group B/C; guarded prognosis requiring immediate total hip arthroplasty.

Correct Answer & Explanation

. Group B; favorable prognosis if the patient is over 8 years old.

Explanation

In the Herring classification, Group C involves >50% loss of lateral pillar height (maintaining <50%). This group has a universally poor prognosis with a high risk of developing an aspherical femoral head and early osteoarthritis, often requiring surgical containment.

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