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 381
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.
Question 382
Topic: Pediatric Hip
Figures 8a and 8b show the current radiographs of a 10-year-old boy with a hip disorder who was treated with an abduction orthosis 3 years ago. If no further remodeling occurs, what is the most likely prognosis?
Correct Answer & Explanation
. Accelerated onset of degenerative arthritis will develop on the involved side in the fifth or sixth decade of life.
Explanation
DISCUSSION: The radiographs show a child with Legg-Calve-Perthes disease (LCPD) that has healed. Deformity (asphericity) of the femoral head is evident, but the femoral head and acetabulum are congruous. Stulberg and associates found that hips with aspherical congruity at skeletal maturity functioned well until the fifth or sixth decade of life. Similarly, another study found that degenerative arthritis caused deteriorating hip function after age 40 years in patients with this degree of residual deformity. Repeated episodes of ischemic necrosis are unlikely. Although some studies suggested coagulation abnormalities such as protein C and S deficiencies in children with LCPD, other studies failed to show any evidence of inherited thrombophilia in most children with this disorder. There are no studies to suggest growth acceleration occurs following LCPD. REFERENCES: Stulberg SD, Cooperman DR, Wallenstein R: The natural history of Legg-Calve-Perthes disease. J Bone Joint Surg Am 1984;66:479-489. McAndrew MP, Weinstein SL: A long-term follow-up of Legg-Calve-Perthes disease. J Bone Joint Surg Am 1984;66:860-869.
Question 383
Topic: Pediatric Hip
Of the following clinical situations, which is most likely to lead to osteonecrosis associated with a slipped capital femoral epiphysis (SCFE)?
Correct Answer & Explanation
. An unstable SCFE
Explanation
DISCUSSION: Osteonecrosis of the femoral head is the most devastating complication of SCFE. There is a 47% incidence of ischemic necrosis associated with an unstable SCFE. By definition, the patient with an unstable SCFE is unable to bear weight even with crutches. Osteonecrosis is most likely associated with the initial femoral head displacement rather than the result of either tamponade from hemarthrosis or from gentle repositioning prior to stabilization. Age, sex, and obesity are not risk factors for osteonecrosis. REFERENCES: Loder RT, Richards BS, Shapiro PS, et al: Acute slipped capital femoral epiphysis: The importance of physeal stability. J Bone Joint Surg Am 1993;75:1134-1140. Herring JA: Tachdjian’s Pediatric Orthopaedics, ed 3. Philadelphia, PA, WB Saunders, 2002, vol 2, pp 711-745.
Question 384
Topic: Pediatric Hip
Figures 39a and 39b show the current radiographs of an 8-year-old girl who has had pain in the left thigh for the past 3 months. She was recently diagnosed with hypothyroidism and started treatment 1 week ago. Examination reveals a mild abductor deficiency limp on the left side. She lacks 30 degrees of internal rotation on the left hip compared with the right hip. Management should consist of
Correct Answer & Explanation
. in situ pinning of both hips.
Explanation
DISCUSSION: The radiographs confirm a slipped capital femoral epiphysis of the left hip, as well as a widened growth plate on the contralateral hip. This is considered a stable slip because the patient is able to walk. Treatment options for stable slips include in situ pinning, bone graft epiphysiodesis, and in some centers severe slips are treated with primary osteotomy and epiphyseal fixation. Percutaneous in situ fixation is the most popular and widely used method of treatment. This juvenile patient has an endocrine condition and a widened growth plate on the right side; therefore, strong consideration should be given to pinning the contralateral hip as a "pre-slip." Muscle strengthening, hip spica casting, and closed reduction have no place in the primary treatment of a stable slipped capital femoral epiphysis. REFERENCES: Loder RT, Richards BS, Shapiro PS, et al: Acute slipped capital femoral epiphysis: The importance of physeal stability. J Bone Joint Surg Am 1993;75:1134-1140. Loder R, Wittenberg B, DeSilva G: Slipped capital femoral epiphysis associated with endocrine disorders. J Pediatr Orthop 1995;15:349-356. Aronson DD, Carlson WE: Slipped capital femoral epiphysis: A prospective study of fixation with a single screw. J Bone Joint Surg Am 1992;74:810-819.
Question 385
Topic: Pediatric Hip
A 12-year-old boy has had left thigh pain for the past 4 months. Examination shows lack of internal rotation and abduction, and external rotation with hip flexion. A radiograph is shown in Figure 87. What is the most appropriate treatment? Review Topic
Correct Answer & Explanation
. Physical therapy
Explanation
The patient has a stable slipped capital femoral epiphysis (SCFE). Preferred treatment of stable SCFE is in situ pinning. In situ fixation of stable SCFE has an extremely low rate of osteonecrosis. Gentle postural reduction with hip capsulotomy or surgical dislocation of the hip with reduction has been advocated for unstable SCFE.
Question 386
Topic: Pediatric Hip
A 3-year-old child has refused to walk for the past 2 days. Examination in the emergency department reveals a temperature of 102.2 degrees F (39 degrees C) and limited range of motion of the left hip. An AP pelvic radiograph is normal. Laboratory studies show a WBC count of 9,000/mm3, an erythrocyte sedimentation rate (ESR) of 65 mm/h, and a C-reactive protein level of 10.5 mg/L (normal < 0.4). What is the next most appropriate step in management?
Correct Answer & Explanation
. Aspiration of the left hip
Explanation
DISCUSSION: Examination reveals an irritable hip, creating a differential diagnosis of transient synovitis versus pyogenic hip arthritis. Kocher and associates described four criteria to help predict the presence of infection: inability to bear weight, fever, ESR of more than 40 mm/h, and a peripheral WBC count of more than 12,000/mm3. This patient meets three of the four criteria, with a positive predictive value of 73% to 93% for joint infection. Therefore, aspiration of the hip is warranted, with a high likelihood that emergent hip arthrotomy will be indicated.
Question 387
Topic: Pediatric Hip
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
Correct Answer & Explanation
. fixation with one or two screws.
Explanation
DISCUSSION: 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.
Question 388
Topic: Pediatric Hip
A 13-year-old boy presents with severe left hip pain and inability to bear weight following a minor fall. Radiographs confirm a severe, unstable slipped capital femoral epiphysis (SCFE). A modified Dunn procedure is considered. What vascular structure is most at risk and must be meticulously protected during the surgical dislocation and callus debridement?
Correct Answer & Explanation
. Medial femoral circumflex artery (MFCA)
Explanation
The deep branch of the medial femoral circumflex artery (MFCA) is the primary blood supply to the femoral head. In the modified Dunn procedure (capital realignment via surgical hip dislocation) for severe unstable SCFE, the retinacular vessels branching from the MFCA must be meticulously preserved as they run along the posterosuperior femoral neck to prevent avascular necrosis (AVN).
Question 389
Topic: Pediatric Hip
A 6-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Which of the following radiographic findings is recognized as one of Catterall's 'head-at-risk' signs, indicating a poorer prognosis?
Correct Answer & Explanation
. Gage's sign
Explanation
Catterall's 'head-at-risk' signs for poor prognosis in Perthes disease include: Gage's sign (a V-shaped radiolucency in the lateral portion of the epiphysis/metaphysis), lateral subluxation of the femoral head, calcification lateral to the epiphysis, diffuse metaphyseal reaction, and a horizontal growth plate.
Question 390
Topic: Pediatric Hip
In the management of Legg-Calve-Perthes disease, the Herring Lateral Pillar Classification is widely used due to its strong prognostic value. Which radiographic feature specifically defines a Herring Group B classification?
Correct Answer & Explanation
. Less than 50% of the lateral pillar height is maintained
Explanation
The Herring Lateral Pillar classification evaluates the height of the lateral third of the femoral head on an AP pelvis radiograph during the fragmentation stage. Group A: No involvement of the lateral pillar. Group B: >50% of lateral pillar height is maintained. Group C: <50% of lateral pillar height is maintained. Group B/C border refers to exactly 50% height.
Question 391
Topic: Pediatric Hip
A 12-year-old obese male undergoes in-situ pinning for a slipped capital femoral epiphysis (SCFE). Intraoperatively, the slip is noted to be unstable as the patient could not bear weight prior to surgery. Compared to a stable SCFE, this patient is at significantly higher risk for which complication?
Correct Answer & Explanation
. Avascular necrosis of the femoral head
Explanation
Unstable SCFE, defined by the inability to bear weight even with crutches, carries a markedly higher risk of avascular necrosis (AVN) compared to stable SCFE. This is due to disruption or kinking of the retinacular vessels.
Question 392
Topic: Pediatric Hip
A 30-year-old male presents with activity-related groin pain. Pelvic radiographs reveal a crossover sign, a prominent ischial spine sign, and a posterior wall sign. Which anatomic abnormality is primarily responsible for his femoroacetabular impingement?
Correct Answer & Explanation
. Acetabular retroversion
Explanation
The crossover sign, ischial spine sign, and posterior wall sign are classic radiographic hallmarks of acetabular retroversion, which leads to focal anterior pincer-type impingement.
Question 393
Topic: Pediatric Hip
A 13-year-old obese boy requires in-situ pinning for a stable slipped capital femoral epiphysis (SCFE). To minimize the risk of joint penetration while maximizing mechanical stability, the single screw should be placed in which zone of the femoral head?
Correct Answer & Explanation
. Anterior-superior
Explanation
In SCFE pinning, the goal is to place a single screw in the center of the epiphysis (central-central position) perpendicular to the physis. This provides optimal stability and minimizes the risk of unrecognized intra-articular screw penetration.
Question 394
Topic: Pediatric Hip
A 6-year-old boy is diagnosed with Legg-Calve-Perthes disease. Radiographs reveal that exactly 60% of the lateral pillar height is maintained. According to the Herring lateral pillar classification, what is his group and the most appropriate standard initial management?
Correct Answer & Explanation
. Group A - Proximal femoral osteotomy
Explanation
Maintenance of >50% lateral pillar height defines Herring Group B. In a patient under the age of 8, Group B disease is typically treated non-operatively with observation, activity modification, and maintaining range of motion.
Question 395
Topic: Pediatric Hip
Figure 10 shows the radiograph of a 7-year-old patient who has a bilateral Trendelenburg limp and limited range of hip motion but no pain. His work-up should include
Correct Answer & Explanation
. a skeletal survey.
Explanation
DISCUSSION: The radiograph shows bilateral flattening of the femoral heads with mottling and “fragmentation” suggestive of Legg-Calve-Perthes disease. However, when these changes occur bilaterally and are symmetric, multiple epiphyseal dysplasia or spondyloepiphyseal dysplasia should be suspected. Skeletal survey will show irregularity of the secondary ossification centers. With these conditions, there is no true osteonecrosis and no evidence that orthotic or surgical “containment” will alter the outcome of progressive degenerative arthritis. Cardiac anomalies and coagulopathies are not associated with the epiphyseal dysplasias. REFERENCES: Crossan JF, Wynne-Davies R, Fulford GE: Bilateral failure of the capital femoral epiphysis: Bilateral Perthes disease, multiple epiphyseal dysplasia, pseudoachondroplasia, and spondyloepiphyseal dysplasia congenita and tarda. J Pediatr Orthop 1983;3:297-301. Sponseller PD: The skeletal dysplasias, in Morrissy RT, Weinstein SL (eds): Lovell and Winter’s Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, pp 269-270.
Question 396
Topic: Pediatric Hip
A 15-year-old girl who swims the breaststroke has had hip pain after training excessively for a national level competition. Based on the MRI scans shown in Figures 5a through 5c, what is the most likely diagnosis?
Correct Answer & Explanation
. External rotator muscle tear
Explanation
Discussion: The MRI scans reveal open physes but no evidence of a slipped capital femoral epiphysis, labral tear, or acetabular dysplasia. The femoral neck does not show evidence of a fracture. The muscle tear seen on the right side lies near the musculotendinous junction of the external rotators of the hip at the level of the lesser trochanter, representing the obturator externus. This is consistent with the forced motion required for the breaststroke kick.
Question 397
Topic: Pediatric Hip
Figure 36 shows the radiograph of a 14-year-old boy who has been treated in the past for Perthes’ disease with an abduction brace. He now has hip pain that limits his activity, and nonsteroidal anti-inflammatory drugs have failed to provide relief. What is the most appropriate treatment?
Correct Answer & Explanation
. Shelf acetabuloplasty
Explanation
Several authors have reported good success in relieving pain with shelf acetabuloplasty. This patient’s Perthes’ disease is in the healed phase; therefore, proximal femoral varus and Salter innominate osteotomies aimed at improving containment are not indicated. The medial one half of the patient’s femoral head is markedly deformed, and rotating it into a weight-bearing position with proximal femoral valgus osteotomy is unlikely to relieve pain. Hip arthrodesis can always be performed as a salvage procedure if the shelf acetabuloplasty fails.
Question 398
Topic: Pediatric Hip
A 12-year-old obese male presents with left knee pain and a limp for 3 weeks. Examination reveals an antalgic gait. When the hip is passively flexed, it falls into obligatory external rotation.
What is the most appropriate definitive management for the left hip?
Correct Answer & Explanation
. In situ percutaneous screw fixation
Explanation
The clinical presentation (obese adolescent, knee/thigh pain, obligatory external rotation with hip flexion) is classic for a Slipped Capital Femoral Epiphysis (SCFE). The standard of care for a stable or unstable SCFE is in situ percutaneous screw fixation (usually a single cannulated screw placed centrally in the epiphysis) to prevent further slippage and promote physeal closure.
Question 399
Topic: Pediatric Hip
A 13-year-old obese male presents with insidious onset of left groin and knee pain. He walks with an externally rotated gait. When his left hip is passively flexed, it obligatory goes into external rotation. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). He undergoes in situ single-screw fixation. Which of the following is the most common long-term complication following successful fixation of this condition?
Correct Answer & Explanation
. Femoroacetabular impingement (FAI)
Explanation
The obligatory external rotation with hip flexion (Drehmann sign) is classic for SCFE. Following in situ fixation of a SCFE, the residual prominent anterior-superior femoral metaphysis frequently leads to Cam-type femoroacetabular impingement (FAI). While avascular necrosis (AVN) is the most devastating complication, it is far more common in unstable SCFE. Chondrolysis is less common today, historically associated with unrecognized intra-articular screw penetration. Thus, FAI is the most common long-term complication even after successful stable in situ pinning.
Question 400
Topic: Pediatric Hip
In a patient with a typical slipped capital femoral epiphysis (SCFE), what is the true anatomic displacement of the femoral metaphysis (femoral neck) relative to the epiphysis?
Correct Answer & Explanation
. Posterior and inferior
Explanation
In a SCFE, the clinical and radiographic appearance is often described as the epiphysis slipping "posterior and inferior." However, biomechanically and anatomically, the epiphysis remains relatively fixed in the acetabulum (tethered by the ligamentum teres). It is the femoral neck (metaphysis) that physically translates anteriorly and superiorly (and externally rotates). This anterior metaphyseal prominence is the classic source of Cam impingement post-SCFE.
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