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Pediatric Hip MCQs

Practice Set 95 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 1881

Topic: Pediatric Hip

When performing a closed reduction and spica casting for developmental dysplasia of the hip (DDH), the 'safe zone' of Ramsey defines the range between:

. Maximum extension and minimum flexion
. Maximum abduction and the angle of re-dislocation in adduction
. Maximum internal rotation and minimum external rotation
. Maximum adduction and the angle of re-dislocation in abduction
. Maximum flexion and the angle of re-dislocation in extension

Correct Answer & Explanation

. Maximum abduction and the angle of re-dislocation in adduction

Explanation

Ramsey's safe zone is the range of abduction between the angle of re-dislocation (when the hip is adducted) and maximum abduction. Keeping the hip within this zone minimizes the risk of re-dislocation while mitigating the risk of avascular necrosis caused by forced extreme abduction.

Question 1882

Topic: Pediatric Hip

Prophylactic in situ pinning of the contralateral asymptomatic hip in a patient with a unilateral slipped capital femoral epiphysis (SCFE) is most strongly indicated in which of the following scenarios?

. A 14-year-old male with a BMI of 25
. A 10-year-old female with idiopathic SCFE
. A 12-year-old male with underlying chronic renal failure
. An 11-year-old female with a slip angle of 15 degrees
. A 15-year-old male with acute trauma

Correct Answer & Explanation

. A 12-year-old male with underlying chronic renal failure

Explanation

Prophylactic contralateral pinning is highly recommended in patients with SCFE related to underlying endocrinopathies or metabolic bone diseases (like chronic renal failure), as well as in patients undergoing radiation therapy or those under 10 years of age, due to the high risk of bilateral involvement.

Question 1883

Topic: Pediatric Hip
In the treatment of Legg-Calvé-Perthes disease, surgical containment yields the most significant improvement in radiographic outcomes compared to nonoperative treatment in which specific patient population?
. Children less than 6 years of age at onset
. Children over 8 years of age at onset with Lateral Pillar B or B/C involvement
. Children over 8 years of age with Lateral Pillar A involvement
. Children of any age with complete Lateral Pillar C collapse
. Adolescents with healed, spherical femoral heads

Correct Answer & Explanation

. Children over 8 years of age at onset with Lateral Pillar B or B/C involvement

Explanation

Studies (e.g., Herring et al.) have demonstrated that surgical containment provides significantly better radiographic outcomes than nonoperative management in children who are over 8 years old at symptom onset and have Lateral Pillar B or B/C border disease. Type C hips perform poorly regardless of treatment.

Question 1884

Topic: Pediatric Hip

A 12-year-old obese male presents with acute-on-chronic left hip pain and inability to bear weight. Radiographs confirm an unstable slipped capital femoral epiphysis (SCFE). What is the most significant risk factor for developing avascular necrosis (AVN) following surgical fixation?

. Open physes
. Obesity
. Degree of initial slip
. Preoperative instability
. Choice of single vs dual screw fixation

Correct Answer & Explanation

. Preoperative instability

Explanation

Preoperative instability (inability to bear weight even with crutches) is the highest risk factor for AVN in SCFE. The risk of AVN in unstable SCFE can be up to 50%, compared to near zero in stable slips.

Question 1885

Topic: Pediatric Hip
In a 7-year-old boy with Legg-Calvé-Perthes disease, which of the following radiographic "head-at-risk" signs (Catterall) suggests a poor prognosis and potential need for surgical containment?
. Increased medial joint space
. Gage sign
. Subchondral fracture
. Calcification lateral to the epiphysis
. Lateral subluxation of the femoral head

Correct Answer & Explanation

. Lateral subluxation of the femoral head

Explanation

Lateral subluxation of the femoral head is a critical "head-at-risk" sign indicating loss of containment and impending hinge abduction. This finding often prompts surgical intervention, such as a varus derotational osteotomy or pelvic osteotomy.

Question 1886

Topic: Pediatric Hip
A 16-year-old female presents with persistent lateral hip pain. Radiographs show a lateral center edge angle (LCEA) of 15 degrees and a Tönnis angle of 18 degrees with an intact Shenton's line. Joint space is preserved. What is the most appropriate surgical treatment?
. Total hip arthroplasty
. Bernese periacetabular osteotomy (PAO)
. Proximal femoral varus osteotomy
. Hip arthroscopy with labral repair
. Shelf arthroplasty

Correct Answer & Explanation

. Bernese periacetabular osteotomy (PAO)

Explanation

This patient has symptomatic developmental dysplasia of the hip (DDH) with preserved joint space. PAO allows powerful reorientation of the acetabulum while preserving the posterior column, making it the ideal treatment for symptomatic dysplasia in adolescents and young adults.

Question 1887

Topic: Pediatric Hip

A 13-year-old boy undergoes in situ pinning of a stable, moderate left SCFE. One year later, he presents with progressive stiffness and pain in the left hip. Examination reveals severe global restriction of hip motion. Radiographs show joint space narrowing and subchondral sclerosis without focal collapse. What is the most likely diagnosis?

. Avascular necrosis (AVN)
. Chondrolysis
. Septic arthritis
. Osteoarthritis
. Hardware failure

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a severe complication of SCFE, presenting with global loss of motion and joint space narrowing. It is commonly associated with unrecognized pin penetration into the joint but can also occur idiopathically in severe slips.

Question 1888

Topic: Pediatric Hip

A 28-year-old hockey player presents with groin pain worsened by deep hip flexion and internal rotation. Radiographs display an alpha angle of 65 degrees. What is the primary pathomechanism of cartilage damage in this specific condition?

. Linear contact between the acetabular rim and femoral neck causing labral infolding
. Pincer impingement leading to contrecoup cartilage lesions posteromedially
. Shear forces at the chondrolabral junction leading to articular cartilage delamination
. Global joint incongruity mimicking developmental dysplasia
. Chondral necrosis secondary to retinacular vascular compression

Correct Answer & Explanation

. Shear forces at the chondrolabral junction leading to articular cartilage delamination

Explanation

Cam impingement (high alpha angle) involves a non-spherical femoral head entering the acetabulum, creating shear forces at the chondrolabral junction. This leads to inside-out delamination of the acetabular cartilage.

Question 1889

Topic: Pediatric Hip
In the evaluation of a 7-year-old boy with Legg-Calvé-Perthes disease, the Herring lateral pillar classification dictates prognosis and treatment. Which of the following radiographic findings correctly defines a Herring Group C classification?
. No loss of height in the lateral pillar
. Less than 50% loss of lateral pillar height
. Greater than 50% loss of lateral pillar height
. A visible subchondral crescent sign extending into the entire lateral pillar
. Medial joint space widening greater than 5 millimeters

Correct Answer & Explanation

. Greater than 50% loss of lateral pillar height

Explanation

The Herring classification assesses the height of the lateral pillar on AP radiographs during the fragmentation phase. Group C is defined by >50% loss of height, portending a poorer prognosis and a higher likelihood of non-spherical healing.

Question 1890

Topic: Pediatric Hip

A 13-year-old obese male sustains an acute-on-chronic slipped capital femoral epiphysis (SCFE) and is unable to bear weight even with crutches. He is treated with single in situ screw fixation. What is the most devastating, yet relatively common, complication specifically associated with this variant of SCFE?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Progressive slip post-fixation
. Intra-articular pin penetration
. Subtrochanteric femur fracture

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

By the Loder classification, the inability to bear weight defines an unstable SCFE. Unstable slips carry a high risk of avascular necrosis (up to 47%), resulting from kinking or disruption of the vulnerable retinacular vessels.

Question 1891

Topic: Pediatric Hip

A 35-year-old female with secondary osteoarthritis due to severe developmental dysplasia of the hip (Crowe Type IV) requires a total hip arthroplasty. To successfully place the acetabular cup in the true acetabulum and safely reduce the hip, which adjunctive procedure is most frequently required?

. Greater trochanteric advancement
. Proximal femoral valgus osteotomy
. Subtrochanteric shortening osteotomy
. Distal femoral extension osteotomy
. Ischial tuberosity osteotomy

Correct Answer & Explanation

. Subtrochanteric shortening osteotomy

Explanation

Crowe Type IV DDH involves a high, completely dislocated hip. Bringing the femoral head down to the true acetabulum heavily stretches the sciatic nerve, routinely requiring a subtrochanteric shortening osteotomy to prevent nerve palsy.

Question 1892

Topic: Pediatric Hip

A 5-year-old girl with developmental dysplasia of the hip (DDH) requires a pelvic osteotomy. The surgeon plans an incomplete osteotomy through the ilium, hinging on the triradiate cartilage, to reduce the acetabular volume and improve anterior and lateral coverage. Which osteotomy is described?

. Salter osteotomy
. Pemberton osteotomy
. Chiari osteotomy
. Steel osteotomy
. Ganz osteotomy

Correct Answer & Explanation

. Pemberton osteotomy

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the triradiate cartilage. It actively alters the shape of the acetabulum and reduces its volume, making it highly effective for true acetabular dysplasia.

Question 1893

Topic: Pediatric Hip

A 12-year-old obese male presents with a unilateral stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest clinical indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Male sex
. Body mass index greater than the 95th percentile
. Age greater than 14 years
. Initial slip angle greater than 50 degrees
. Presentation with a concomitant endocrine disorder

Correct Answer & Explanation

. Presentation with a concomitant endocrine disorder

Explanation

Endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy) carry a very high risk of bilateral involvement in SCFE. This makes underlying endocrinopathy a strong, widely accepted indication for prophylactic pinning of the contralateral hip.

Question 1894

Topic: Pediatric Hip

A 5-year-old boy is evaluated for a painless waddling gait. Radiographs show developmental coxa vara. The Hilgenreiner's epiphyseal angle (HEA) is measured at 65 degrees. What is the most appropriate management?

. Observation and annual radiographs
. Hip spica casting
. Proximal femoral valgus osteotomy
. Greater trochanteric epiphysiodesis
. Pelvic support osteotomy

Correct Answer & Explanation

. Proximal femoral valgus osteotomy

Explanation

An HEA greater than 60 degrees in developmental coxa vara generally indicates a progressive deformity that will not resolve spontaneously. A proximal femoral valgus osteotomy is required to correct the neck-shaft angle and mechanical axis.

Question 1895

Topic: Pediatric Hip
A 45-year-old male presents with early-onset hip osteoarthritis. He has a history of Legg-Calvé-Perthes disease as a child. Radiographs show an enlarged, flat femoral head that is congruent with a similarly flattened acetabulum. This presentation most closely correlates with which Stulberg classification from childhood?
. Stulberg I
. Stulberg II
. Stulberg III
. Stulberg IV
. Stulberg V

Correct Answer & Explanation

. Stulberg III

Explanation

Stulberg III describes an aspherical but congruent joint (coxa magna), which leads to mild-to-moderate osteoarthritis in middle age. Stulberg IV and V are aspherical and incongruent, typically leading to severe, early arthritis before age 40.

Question 1896

Topic: Pediatric Hip

A 6-month-old girl undergoes closed reduction and spica casting for developmental dysplasia of the hip. Which of the following positions during casting is most heavily associated with the development of iatrogenic avascular necrosis (AVN) of the femoral head?

. Hip flexion of 90 degrees and abduction of 45 degrees
. Hip flexion of 100 degrees and adduction of 10 degrees
. Extreme hip abduction greater than 60 degrees with internal rotation
. Hip extension and external rotation
. Hip flexion of 60 degrees and neutral abduction

Correct Answer & Explanation

. Extreme hip abduction greater than 60 degrees with internal rotation

Explanation

Immobilization in extreme hip abduction (the 'frog-leg' position) increases pressure on the delicate retinacular vessels. This dramatically increases the risk of iatrogenic avascular necrosis of the femoral head in DDH treatment.

Question 1897

Topic: Pediatric Hip

A 12-year-old boy with a BMI in the 98th percentile presents with 3 weeks of insidious onset left groin pain and a limp. Radiographs confirm a mild slipped capital femoral epiphysis (SCFE). What is the most appropriate initial management?

. Spica cast immobilization
. Closed reduction and percutaneous pinning
. In situ single screw fixation
. Open reduction and surgical subluxation
. Observation and non-weight-bearing with crutches

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The standard of care for a stable, mild to moderate SCFE is in situ single screw fixation using a fully threaded screw to promote physeal closure and prevent further slippage. Closed reduction increases the risk of avascular necrosis and is generally contraindicated.

Question 1898

Topic: Pediatric Hip

A 6-week-old female infant with an irreducible developmental dysplasia of the hip (DDH) is placed in a Pavlik harness. After 3 weeks of strict, full-time wear, an ultrasound shows the hip remains completely dislocated. What is the next most appropriate step in management?

. Continue the Pavlik harness for an additional 3 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld splint)
. Immediate closed reduction and spica casting
. Immediate open reduction and spica casting
. Discontinue treatment and observe until 6 months of age for surgical intervention

Correct Answer & Explanation

. Transition to a rigid abduction orthosis (e.g., Ilfeld splint)

Explanation

If a Pavlik harness fails to achieve reduction after 3 to 4 weeks, it should be discontinued to prevent "Pavlik harness disease" (damage to the posterior acetabular lip). Transitioning to a rigid abduction orthosis is the standard next step before considering closed reduction under anesthesia.

Question 1899

Topic: Pediatric Hip

In addition to hypoplastic or absent clavicles, which of the following is a classic radiographic finding associated with cleidocranial dysplasia?

. Coxa valga
. Premature closure of cranial sutures
. Widened symphysis pubis
. Acetabular protrusio
. Erlenmeyer flask deformity of the distal femur

Correct Answer & Explanation

. Widened symphysis pubis

Explanation

Cleidocranial dysplasia is associated with delayed ossification of midline structures. Classic findings include a widened symphysis pubis, delayed closure of cranial sutures (with wormian bones), and coxa vara.

Question 1900

Topic: Pediatric Hip

A 15-year-old boy presents for evaluation of delayed dental eruption. Examination reveals open skull sutures and absent clavicles.

Which of the following associated orthopedic conditions should also be screened for in this patient?

. Coxa vara
. Atlantoaxial instability
. Radial head dislocation
. Slipped capital femoral epiphysis
. Tibia vara

Correct Answer & Explanation

. Coxa vara

Explanation

Patients with cleidocranial dysplasia frequently develop coxa vara and scoliosis. Screening for these orthopedic manifestations is standard in managing the condition.

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