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 401
Topic: Pediatric Hip
A 28-year-old male hockey player presents with groin pain exacerbated by hip flexion and internal rotation. An AP pelvis radiograph demonstrates a 'crossover sign' and a 'prominent ischial spine sign.' These radiographic findings are most indicative of which of the following pathologies?
Correct Answer & Explanation
. Cam-type femoroacetabular impingement
Explanation
The crossover sign (anterior wall of the acetabulum crossing the posterior wall), prominent ischial spine sign, and posterior wall sign are radiographic markers of acetabular retroversion. This focal overcoverage leads to pincer-type femoroacetabular impingement (FAI).
Question 402
Topic: Pediatric Hip
A 45-year-old female presents with severe end-stage osteoarthritis secondary to developmental dysplasia of the hip (DDH). Radiographs demonstrate complete dislocation of the femoral head with proximal migration greater than 100% of the femoral head height (Crowe IV).
During total hip arthroplasty, the acetabular component is placed at the level of the true acetabulum. Which of the following is the most appropriate technique to safely reduce the hip and minimize the risk of sciatic nerve palsy?
Correct Answer & Explanation
. Aggressive intraoperative stretching of the sciatic nerve
Explanation
In Crowe IV DDH, restoring the anatomic center of rotation (true acetabulum) often requires distalizing the femur several centimeters. To accomplish this without causing catastrophic stretching of the sciatic nerve (lengthening > 4cm is high risk), a subtrochanteric shortening osteotomy is frequently required.
Question 403
Topic: Pediatric Hip
A 12-year-old boy presents with left hip pain and an acutely worsening limp. Radiographs confirm a severe, unstable slipped capital femoral epiphysis (SCFE) of the left hip. The right hip is radiographically normal and asymptomatic. Which of the following is the strongest universally accepted indication for prophylactic in situ pinning of the contralateral asymptomatic hip?
Correct Answer & Explanation
. Modified Southwick angle greater than 50 degrees on the affected side
Explanation
The primary indications for prophylactic pinning of a contralateral asymptomatic hip in a patient with SCFE include an underlying endocrine or metabolic disorder (e.g., hypothyroidism, renal osteodystrophy), patient age less than 10 years, and open triradiate cartilage. These factors represent a high risk for subsequent contralateral slip.
Question 404
Topic: Pediatric Hip
A 12-year-old boy presents with right-sided groin pain and an externally rotated leg. Radiographs confirm a unilateral slipped capital femoral epiphysis (SCFE). Which of the following conditions constitutes the strongest absolute indication for prophylactic in situ pinning of the asymptomatic contralateral hip?
Correct Answer & Explanation
. Age of 14 years
Explanation
Patients with an underlying endocrinopathy (such as hypothyroidism) or renal osteodystrophy have an exceptionally high risk of developing contralateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these systemic conditions.
Question 405
Topic: Pediatric Hip
A 12-year-old overweight male presents with an atraumatic limp and left knee pain. An AP radiograph of the pelvis reveals a positive Trethowan sign. Which of the following defines a positive Trethowan sign in this context?
Correct Answer & Explanation
. A line drawn along the superior border of the femoral neck failing to intersect the lateral portion of the femoral epiphysis
Explanation
The Trethowan sign is defined by Klein's line. Klein's line is drawn along the superior border of the femoral neck on an AP radiograph. In a normal hip, this line intersects the lateral portion of the capital femoral epiphysis. A positive Trethowan sign occurs when Klein's line does not intersect the epiphysis, highly indicative of a Slipped Capital Femoral Epiphysis (SCFE).
Question 406
Topic: Pediatric Hip
A 12-year-old obese male presents with a stable, mild slipped capital femoral epiphysis (SCFE) of the left hip. Under which of the following circumstances is prophylactic in situ pinning of the contralateral, asymptomatic right hip most strongly indicated?
Correct Answer & Explanation
. Presence of a diagnosed underlying endocrine disorder such as hypothyroidism
Explanation
While prophylactic pinning of the contralateral hip in SCFE remains controversial for idiopathic cases, it is strongly indicated in patients with underlying endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency). These patients have an extremely high risk (often >50-80%) of developing bilateral SCFE. Other relative indications for prophylactic pinning include younger age (e.g., girls <10, boys <12) and open triradiate cartilage (modified Oxford bone age).
Question 407
Topic: Pediatric Hip
A 12-year-old obese male presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. The surgeon recommends in situ pinning of the left hip. What is the most widely accepted absolute indication for prophylactic in situ pinning of the asymptomatic, contralateral right hip?
Correct Answer & Explanation
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
Explanation
Prophylactic pinning of the contralateral hip in SCFE is universally recommended for patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or prior pelvic radiation, as their risk of developing a contralateral slip is exceedingly high (up to 100%).
Question 408
Topic: Pediatric Hip
In a 12-year-old male presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following factors is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?
Correct Answer & Explanation
. Underlying endocrine disorder
Explanation
While unilateral SCFE can progress to bilateral disease in about 20-40% of cases, patients with underlying endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency) have an exceptionally high risk of bilateral involvement (up to 100% in some series). Therefore, an underlying endocrinopathy is a strong and widely accepted absolute indication for prophylactic pinning of the contralateral hip.
Question 409
Topic: Pediatric Hip
When performing a total hip arthroplasty on a patient with Crowe Type IV developmental dysplasia of the hip (DDH), the true native acetabulum is characteristically deficient in which of the following regions?
Correct Answer & Explanation
. Anterior and superior
Explanation
In developmental dysplasia of the hip (DDH), the true acetabulum is classically shallow, with the greatest bony deficiency located in the anterior and superior walls. This morphological abnormality necessitates careful preoperative planning for acetabular cup placement and often requires the use of structural bone grafts or specialized augments to achieve adequate superior-anterior coverage.
Question 410
Topic: Pediatric Hip
A 13-year-old obese male presents to the emergency department with acute-on-chronic left knee pain and an absolute inability to bear weight on the left lower extremity. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following factors is the most significant predictor for the development of avascular necrosis (AVN) in this patient?
Correct Answer & Explanation
. The clinical instability of the slip (inability to bear weight)
Explanation
According to the Loder classification, SCFE is divided into stable (able to bear weight) and unstable (unable to bear weight, even with crutches). Unstable slips carry a significantly higher risk of avascular necrosis (AVN), reported to be up to 47%, whereas stable slips have an AVN rate approaching zero. This clinical feature is the most important prognostic factor for AVN.
Question 411
Topic: Pediatric Hip
A 4-month-old infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At the two-week follow-up, the mother reports that the infant has stopped kicking the leg on the affected side. Examination reveals an absent patellar reflex and profound quadriceps weakness. What is the most likely cause of this finding, and what is the next best step in management?
Correct Answer & Explanation
. Femoral nerve palsy from excessive hip flexion; temporarily loosen the anterior straps or discontinue the harness.
Explanation
Femoral nerve palsy is a known complication of Pavlik harness treatment, caused by hyperflexion of the hip which compresses the nerve against the pelvis. It presents with decreased active knee extension and an absent patellar reflex. The appropriate management is to loosen the anterior flexion straps or temporarily discontinue the harness to allow the nerve to recover, which it typically does within days to weeks.
Question 412
Topic: Pediatric Hip
A 12-year-old obese boy presents with a left-sided stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in situ pinning of the asymptomatic right hip?
Correct Answer & Explanation
. Presence of an endocrine disorder such as hypothyroidism
Explanation
Prophylactic pinning of the contralateral hip in SCFE is controversial but is strongly recommended in patients with endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) due to the exceedingly high risk of bilateral involvement. Age less than 10, open triradiate cartilage, and prior radiation therapy are also considered indications for prophylactic fixation.
Question 413
Topic: Pediatric Hip
A 22-year-old female is evaluated for symptomatic developmental dysplasia of the hip (DDH). Preoperative planning for a Bernese periacetabular osteotomy (PAO) is underway. Which of the following is a strict prerequisite for a successful PAO in this patient?
Correct Answer & Explanation
. A completely closed triradiate cartilage
Explanation
The Bernese periacetabular osteotomy (PAO) is indicated for symptomatic DDH in adolescents and young adults. A strict prerequisite is a closed triradiate cartilage to prevent growth arrest, as the osteotomy cuts through the ilium, ischium, and pubis around the acetabulum. Advanced osteoarthritis (Tonnis grade 2 or 3) is a relative contraindication, and the joint must demonstrate congruency on functional (abduction/internal rotation) views to ensure the redirected acetabulum will articulate properly.
Question 414
Topic: Pediatric Hip
A 9-year-old boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of the left hip. Prophylactic pinning of the asymptomatic, radiographically normal contralateral right hip is strongly indicated if the patient has a history of which of the following?
Correct Answer & Explanation
. Recent growth hormone therapy or hypothyroidism
Explanation
The overall risk of a contralateral slip in patients with SCFE is approximately 20-25%. However, prophylactic pinning of the contralateral asymptomatic hip is strongly recommended in patients with specific high-risk profiles, including underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or growth hormone therapy), previous pelvic radiation therapy, or presentation at an unusually young age (typically under 10 years for boys).
Question 415
Topic: Pediatric Hip
A 6-week-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. Her hips were noted to be dislocated and irreducible (Ortolani negative) at presentation. Ultrasound at 3 weeks shows persistent dislocation. What is the most appropriate next step in management?
Correct Answer & Explanation
. Discontinue the Pavlik harness and switch to rigid abduction bracing or plan for closed reduction
Explanation
Continued use of a Pavlik harness in an persistently dislocated (irreducible) hip beyond 3 to 4 weeks is strictly contraindicated. Prolonged use in this setting compresses the femoral head against the posterior acetabular rim, causing 'Pavlik harness disease' (erosion of the posterior acetabulum) and a significantly increased risk of avascular necrosis. The harness must be abandoned in favor of rigid bracing or transition to closed reduction and spica casting.
Question 416
Topic: Pediatric Hip
A 12-year-old obese male presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. During surgical planning, prophylactic pinning of the asymptomatic right hip is discussed. Which of the following is the strongest specific indication for prophylactic pinning of the contralateral hip?
Correct Answer & Explanation
. Presence of an underlying endocrine disorder such as hypothyroidism or renal osteodystrophy
Explanation
While there is ongoing debate regarding universal prophylactic pinning of the contralateral hip in SCFE, strong, generally accepted indications include the presence of an underlying endocrine or metabolic disorder (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or previous radiation therapy. These conditions carry a much higher risk (often >50%) of bilateral involvement compared to idiopathic cases.
Question 417
Topic: Pediatric Hip
A 13-year-old obese boy presents to the emergency department with severe left hip pain and inability to bear weight for the past 24 hours. Radiographs confirm a slipped capital femoral epiphysis (SCFE). He cannot ambulate even with crutches. Which of the following management strategies minimizes the risk of avascular necrosis in this patient?
Correct Answer & Explanation
. Urgent open reduction and internal fixation with capsulotomy
Explanation
This is an unstable SCFE, defined by the inability to bear weight, which carries a high risk of avascular necrosis (AVN). Urgent incidental reduction, fixation, and capsulotomy/decompression is advocated to relieve intracapsular tamponade and reduce AVN risk.
Question 418
Topic: Pediatric Hip
A 13-year-old boy presents with severe left hip pain and inability to bear weight after a minor fall 2 days ago. Radiographs demonstrate a displaced slipped capital femoral epiphysis (SCFE). Which of the following is the most significant prognostic factor for the development of avascular necrosis (AVN)?
Correct Answer & Explanation
. Instability of the slip
Explanation
An unstable slip, defined by the inability to bear weight even with crutches, is the most significant risk factor for developing AVN. Rates of AVN in unstable SCFE can be as high as 47%, compared to nearly 0% in stable SCFE.
Question 419
Topic: Pediatric Hip
A 4-week-old female infant is diagnosed with a completely dislocated left hip that is reducible on examination (Ortolani positive). A Pavlik harness is applied. At the 3-week follow-up ultrasound, the hip remains persistently dislocated. What is the most appropriate next step in management?
Correct Answer & Explanation
. Discontinue the harness and plan for closed reduction with spica casting
Explanation
Failure of a Pavlik harness to achieve reduction of a dislocated hip within 3 to 4 weeks is an absolute indication to discontinue the harness to prevent Pavlik harness disease (posterior acetabular wear). The next appropriate step is typically a closed reduction and spica casting under anesthesia.
Question 420
Topic: Pediatric Hip
A 48-year-old woman reports bilateral thigh pain that is limiting her function as a librarian. A radiograph and a bone scan are shown in Figures 23a and 23b. What is the most likely diagnosis?
Correct Answer & Explanation
. Rheumatoid arthritis
Explanation
The radiograph reveals bilateral severe acetabular protrusio. The bone scan and history confirm involvement of multiple joints, including the knees and the hindfoot. Although the first four choices can all cause the acetabular protrusio, the associated multiple joint involvement suggests the diagnosis of rheumatoid arthritis. Arthrokatadysis, or primary protrusio acetabuli, is often associated with osteomalacia but not other joint disease. Developmental dysplasia is a common cause of bilateral hip pathology but does not have acetabular protrusio. Resnick D: Diagnosis of Bone and Joint Disorders, ed 3. Philadelphia, PA, WB Saunders, 1995, pp 956-957. Wheeless' Textbook of Orthopaedics: Acetabular Protrusio. www.wheelessonline.com/ortho/acetabular_protrusio
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