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Pediatric Hip MCQs

Practice Set 13 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 241

Topic: Pediatric Hip

A 13-year-old overweight boy presents with a limp and right groin pain for 3 weeks. On physical examination, as the right hip is passively flexed, the limb obligatorily rotates externally. What is the most likely diagnosis?

. Legg-Calve-Perthes disease
. Transient synovitis
. Slipped capital femoral epiphysis (SCFE)
. Developmental dysplasia of the hip
. Septic arthritis of the hip

Correct Answer & Explanation

. Slipped capital femoral epiphysis (SCFE)

Explanation

Obligatory external rotation with passive hip flexion is the classic clinical sign of a Slipped Capital Femoral Epiphysis (SCFE). This occurs most commonly in overweight adolescents during their growth spurt.

Question 242

Topic: Pediatric Hip
In a child diagnosed with Legg-Calvé-Perthes disease (idiopathic avascular necrosis of the proximal femoral epiphysis), what is the single most significant independent prognostic factor for developing premature hip osteoarthritis in adulthood?
. Age of the patient at the time of clinical onset
. The gender of the patient
. The presence of an ipsilateral knee effusion
. The patient's body mass index (BMI) at diagnosis

Correct Answer & Explanation

. Age of the patient at the time of clinical onset

Explanation

Age at clinical onset is the most critical prognostic factor in Legg-Calvé-Perthes disease. Children who present at a younger age (typically under 6 to 8 years) have significantly more time for remodeling and generally achieve much better long-term outcomes.

Question 243

Topic: Pediatric Hip

A 4-month-old infant is undergoing closed reduction for developmental dysplasia of the hip (DDH). The intraoperative arthrogram demonstrates medial pooling of dye and a failure to achieve concentric reduction. Which anatomic structure most commonly blocks closed reduction extracapsularly?

. Ligamentum teres
. Pulvinar
. Transverse acetabular ligament
. Inverted limbus
. Iliopsoas tendon

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

While the pulvinar, ligamentum teres, and transverse acetabular ligament are common intracapsular blocks to reduction, the iliopsoas tendon is classically the most significant extracapsular block to closed reduction in DDH.

Question 244

Topic: Pediatric Hip

A 13-year-old obese boy presents with left thigh pain and an obligatory external rotation of the hip during active flexion. A diagnosis of Slipped Capital Femoral Epiphysis (SCFE) is made. What is the most devastating complication associated with forceful closed reduction of a displaced SCFE?

. Chondrolysis of the hip joint
. Avascular necrosis (AVN) of the femoral head
. Premature physeal closure
. Femoroacetabular impingement (CAM type)
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

Forceful or non-gentle closed reduction of a SCFE significantly increases the risk of avascular necrosis of the femoral head by kinking or tearing the already tenuous retinacular blood supply.

Question 245

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of left thigh pain and a limp.

On physical examination, his left hip obligatorily externally rotates when flexed. What is the most appropriate definitive treatment?

. Closed reduction and spica casting
. In situ single screw fixation
. Closed reduction and pinning
. Proximal femoral osteotomy
. Observation with protected weight-bearing

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The clinical presentation of obligatory external rotation with hip flexion in an obese adolescent is classic for slipped capital femoral epiphysis (SCFE). The gold standard treatment is in situ fixation with a single cannulated screw.

Question 246

Topic: Pediatric Hip

A 12-year-old obese male presents with a stable slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning. Six months later, he develops severe hip stiffness and a flexion contracture. Radiographs show significant uniform loss of the joint space. What is the most likely diagnosis?

. Avascular necrosis (AVN)
. Chondrolysis
. Implant failure
. Femoroacetabular impingement (FAI)
. Septic arthritis

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a severe complication of SCFE characterized by progressive stiffness, pain, and uniform loss of joint space. It is strongly associated with unrecognized pin penetration into the joint space during fixation.

Question 247

Topic: Pediatric Hip

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the infant is noted to have absent spontaneous extension of the knee on the treated side. Which nerve is most likely compressed due to improper harness positioning?

. Sciatic nerve
. Obturator nerve
. Femoral nerve
. Lateral femoral cutaneous nerve
. Tibial nerve

Correct Answer & Explanation

. Femoral nerve

Explanation

Hyperflexion of the hip in a Pavlik harness can compress the femoral nerve, leading to decreased quadriceps function and absent knee extension. Treatment involves loosening or temporarily removing the anterior straps.

Question 248

Topic: Pediatric Hip

Prophylactic in situ pinning of the contralateral asymptomatic hip in Slipped Capital Femoral Epiphysis (SCFE) is most strongly indicated in a patient with which of the following underlying conditions?

. Obesity
. Hypothyroidism
. Attention deficit hyperactivity disorder
. Type 1 Diabetes Mellitus
. Trisomy 21

Correct Answer & Explanation

. Hypothyroidism

Explanation

Endocrine disorders, such as hypothyroidism and renal osteodystrophy, significantly increase the risk of bilateral SCFE. In these populations, prophylactic pinning of the contralateral asymptomatic hip is highly recommended due to the high rate of subsequent slippage.

Question 249

Topic: Pediatric Hip

A 3-month-old infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. Hyperflexion of the hips in the harness places the child at highest risk for which of the following complications?

. Avascular necrosis of the femoral head
. Femoral nerve palsy
. Sciatic nerve palsy
. Inferior hip dislocation
. Obturator nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion of the hips in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy. In contrast, excessive abduction is the primary risk factor for avascular necrosis.

Question 250

Topic: Pediatric Hip

A 13-year-old obese male presents with acute-on-chronic left hip pain and inability to bear weight. Radiographs confirm a severe, unstable slipped capital femoral epiphysis (SCFE). Which of the following factors is most strongly associated with the development of avascular necrosis (AVN) in this patient?

. Degree of initial slip displacement
. Time to surgical intervention greater than 24 hours
. Use of a single cannulated screw instead of two
. Inability to bear weight prior to surgery
. Prophylactic pinning of the contralateral hip

Correct Answer & Explanation

. Inability to bear weight prior to surgery

Explanation

Unstable SCFE, defined clinically by the inability to bear weight even with crutches, has the highest association with developing AVN. While aggressive reduction can also cause AVN, clinical instability is the primary patient-related prognostic factor.

Question 251

Topic: Pediatric Hip

A 4-month-old infant is diagnosed with developmental dysplasia of the hip (DDH) after an ultrasound demonstrates a dislocated left hip with an alpha angle of 40 degrees. A Pavlik harness is prescribed. Which complication is most likely if the hip is positioned in excessive flexion?

. Femoral nerve palsy
. Avascular necrosis of the femoral head
. Obturator nerve palsy
. Inferior dislocation of the hip
. Acetabular dysplasia

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive flexion (>120 degrees) in a Pavlik harness can stretch and compress the femoral nerve, leading to a femoral nerve palsy. Excessive abduction, on the other hand, is the primary risk factor for avascular necrosis of the femoral head.

Question 252

Topic: Pediatric Hip

A 12-year-old obese male undergoes in situ pinning for a stable slipped capital femoral epiphysis (SCFE). Post-operatively, it is discovered that the screw penetrated the anterosuperior quadrant of the femoral head into the joint unrecognized. What is the most likely complication?

. Avascular necrosis of the femoral head
. Chondrolysis
. Slip progression
. Femoral neck fracture
. Premature physeal closure leading to leg length discrepancy

Correct Answer & Explanation

. Chondrolysis

Explanation

Unrecognized intra-articular hardware penetration during SCFE fixation is the most common iatrogenic cause of chondrolysis. It leads to rapid, irreversible loss of articular cartilage and profound joint stiffness.

Question 253

Topic: Pediatric Hip

During the ultrasound evaluation of a 6-week-old infant for developmental dysplasia of the hip (DDH), the Graf classification is utilized. What anatomical landmark defines the baseline for measuring the alpha angle?

. The bony roof of the acetabulum
. The cartilaginous roof of the acetabulum
. The straight portion of the ilium
. The triradiate cartilage
. The labrum

Correct Answer & Explanation

. The straight portion of the ilium

Explanation

In the Graf ultrasound technique, the baseline is drawn along the straight portion of the ilium. The alpha angle is measured between this baseline and the bony acetabular roof line, with an angle greater than 60 degrees considered normal.

Question 254

Topic: Pediatric Hip

A 12-year-old boy with a history of panhypopituitarism presents with a stable, slipped capital femoral epiphysis (SCFE) of the left hip. What is the most appropriate management regarding the contralateral right hip?

. Prophylactic in situ pinning
. Observation with serial radiographs
. Spica casting
. Corrective osteotomy
. Epiphysiodesis

Correct Answer & Explanation

. Prophylactic in situ pinning

Explanation

Prophylactic contralateral pinning is strongly recommended in patients with SCFE associated with underlying endocrine disorders, such as panhypopituitarism or hypothyroidism, due to the extremely high risk of bilateral involvement.

Question 255

Topic: Pediatric Hip

A 6-week-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her follow-up examination, she is noted to have a new inability to actively extend her knee on the treated side. What is the most likely cause of this complication?

. Avascular necrosis of the femoral head
. Femoral nerve palsy from excessive hip flexion
. Sciatic nerve palsy from excessive hip abduction
. Obturator nerve palsy
. Ischemic contracture of the quadriceps

Correct Answer & Explanation

. Femoral nerve palsy from excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically caused by excessive hyperflexion of the hips compressing the nerve against the inguinal ligament. It manifests as a loss of active knee extension and usually resolves with temporary harness adjustment.

Question 256

Topic: Pediatric Hip

A 12-year-old boy presents with an acute on chronic slipped capital femoral epiphysis (SCFE) and is entirely unable to bear weight. Following in situ pinning, what is the most significant risk factor for the development of avascular necrosis (AVN) of the femoral head?

. Age greater than 10 years
. Obesity (>95th percentile)
. Unstable nature of the slip
. Bilateral presentation
. Male sex

Correct Answer & Explanation

. Unstable nature of the slip

Explanation

An unstable SCFE is defined by the inability to bear weight even with crutches. Unstable slips have a significantly higher rate of avascular necrosis (up to 50%) compared to stable slips.

Question 257

Topic: Pediatric Hip

A 6-month-old infant with developmental dysplasia of the hip (DDH) fails initial treatment with a Pavlik harness after 4 weeks. What is the next most appropriate step in management?

. Observation until 1 year of age
. Closed reduction and spica casting
. Immediate open reduction
. Femoral derotational osteotomy
. Pelvic osteotomy (Salter)

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

If a Pavlik harness fails to achieve reduction after 3 to 4 weeks in an infant, it should be discontinued to prevent "Pavlik harness disease" (posterior acetabular wear). The next step is a closed reduction and spica casting under anesthesia.

Question 258

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin pain and an obligatory external rotation of the hip during passive flexion. Which of the following is an absolute indication for open reduction and internal fixation of this condition rather than in-situ pinning?

. Stable SCFE with a slip angle > 50 degrees
. Unstable SCFE with an inability to bear weight
. Bilateral SCFE
. There is no absolute indication for open reduction over in-situ pinning
. Presence of a metaphyseal blanch sign of Steel

Correct Answer & Explanation

. There is no absolute indication for open reduction over in-situ pinning

Explanation

In-situ pinning remains the gold standard for both stable and unstable Slipped Capital Femoral Epiphysis (SCFE) to minimize the risk of osteonecrosis. Open reduction (e.g., modified Dunn procedure) is controversial and not considered an absolute indication.

Question 259

Topic: Pediatric Hip

A 13-year-old obese boy undergoes in-situ percutaneous pinning for a stable slipped capital femoral epiphysis (SCFE). He presents 6 months later with worsening hip stiffness and pain. Radiographs demonstrate joint space narrowing and subchondral cyst formation but no avascular necrosis. What is the most likely diagnosis?

. Chondrolysis
. Avascular necrosis
. Hardware failure
. Septic arthritis
. Femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a known complication of SCFE, characterized by progressive loss of articular cartilage and joint stiffness. It is associated with unrecognized intra-articular pin penetration, though it can occur idiopathically in the setting of the disease itself.

Question 260

Topic: Pediatric Hip

An infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the infant is noted to have an absent spontaneous quadriceps contraction and decreased active knee extension. Which of the following harness adjustments is required?

. Increase the flexion straps
. Decrease the flexion straps
. Increase the abduction straps
. Decrease the abduction straps
. Discontinue the harness entirely and cast immediately

Correct Answer & Explanation

. Decrease the flexion straps

Explanation

The clinical presentation is consistent with a femoral nerve palsy, a known complication caused by hyperflexion of the hips in the Pavlik harness. The most appropriate immediate management is to decrease the tension on the anterior flexion straps to alleviate nerve compression.

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