This practice set contains high-yield board review questions covering key concepts in 4. Pediatrics. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 1861
Topic: 4. Pediatrics
A newborn with myelomeningocele has no movement below the waist and has bilateral hips that dislocate with provocative flexion and adduction. What is the best treatment option for the hip instability?
Correct Answer & Explanation
. Observation with range-of-motion exercises to minimize contractures
Explanation
The status of the hips (located or dislocated) in children with thoracic-level myelomeningocele has no effect on the functional outcome of these patients. Management of unstable hips in this population should be limited to treatment of the contractures that may lead to poor limb positioning in either braces or a wheelchair. The use of the Pavlik harness and/or spica cast is contraindicated because they would promote flexion and abduction contractures. In the past, open reduction either through an anterior or medial approach had been performed with a high incidence of redislocation and other complications, with little functional gain for the child. Gabriel KG: Natural history of hip deformity in spina bifida, in Sarwark JR, Lubicky JP (eds): Caring for the Child With Spina Bifida. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2001, pp 89-103.
Question 1862
Topic: Pediatric Upper Extremity & Spine
A 34-year-old man underwent a transtibial amputation as the result of a work-related injury. The amputation was performed at the inferior level of the tibial tubercle. The residual limb has a soft-tissue envelope composed of gastrocnemius muscle that is used as soft-tissue cushioning for the distal tibia. Despite undergoing several prosthetic fittings, he continues to report pain and instability. Examination reveals that the prosthesis appears to fit well with no apparent pressure points or areas of skin breakdown. He is not willing to have any further surgery. Which of the following modifications will most likely provide relief?
Correct Answer & Explanation
. Add double metal uprights and a leather corset.
Explanation
While transtibial amputees can be fitted with a prosthesis with a residual limb as short as 5 cm, or with retention of the insertion of the patellar tendon, this patient has an unstable gait because of the limited ability of the prosthetic socket to maintain a snug and stable fit. While cumbersome and bulky, double metal uprights and a corset is the only predictable method of gaining stability. The other methods attempt to add an element of stability; however, they are unlikely to be successful. Bowker JH, Goldberg B, Poonekar PD: Transtibial amputation: Surgical procedures and postsurgical management, in Bowker JH, Michael JW (eds): Atlas of Limb Prosthetics. St Louis, MO, Mosby Year Book, 1992, pp 429-452.
Question 1863
Topic: 4. Pediatrics
A 6-year-old boy with severe spastic quadriplegic cerebral palsy is nonambulatory. Examination reveals 10 degrees of hip abduction on the left and 30 degrees on the right with the hips and knees extended. The Thomas test shows 20 degrees of flexion bilaterally, and Ely test results are 3+/4 bilaterally. Radiographs show a center edge angle of 0 degrees on the left and -10 degrees on the right. The neck shaft angles are 170 degrees bilaterally. Which of the following procedures would offer the best results?
The patient has bilateral subluxated hips, with nearly vertical neck shaft angles; therefore, the treatment of choice is varus derotation osteotomy. Shortening of the bone on one or both sides may be necessary to allow adequate range of motion postoperatively. In patients this age and with this degree of bony deformity, soft-tissue releases are not likely to lead to hip stability. Botulinum toxin has been shown to be effective in the treatment of ankle equinus, but its efficacy in other areas has not been demonstrated as yet. The indications for obturator neurectomy are unclear at present. Proximal femoral resection is a salvage procedure for long-standing hip dislocations that are symptomatic and not reconstructable. Tylkowski CM, Rosenthal RK, Simon SR: Proximal femoral osteotomy in cerebral palsy. Clin Orthop 1980;151:183-192.
Question 1864
Topic: 4. Pediatrics
A newborn girl with an isolated unilateral dislocatable hip is placed in a Pavlik harness with the hips flexed 100 degrees and at resting abduction. Figure 23 shows an ultrasound obtained 2 weeks later. What is the next step in management?
Correct Answer & Explanation
. Continued harness treatment in the current position
Explanation
The infant has a well-positioned hip in the Pavlik harness and treatment should be continued in the current position. The success rate is over 90% with the use of this device for a dislocatable hip. Ultrasound is a useful tool to confirm appropriate positioning of the cartilaginous femoral head during treatment. If the femoral head is not reduced after 2 to 3 weeks in the harness, this mode of treatment should be abandoned. Forceful extreme abduction can cause osteonecrosis of the femoral epiphysis and should be avoided. Closed reduction, arthrography, and spica casting are indicated if the hip cannot be maintained in a reduced position with the harness. Lehmann HP, Hinton R, Morello P, et al: Developmental dysplasia of the hip practice guideline: Technical report. Committee on Quality Improvement, and Subcommittee on Developmental Dysplasia of the Hip. Pediatrics 2000;105:E57.
Question 1865
Topic: 4. Pediatrics
Thyroid hormone regulates skeletal growth at the physis by stimulation of
Correct Answer & Explanation
. chondrocyte hypertrophy, type X collagen synthesis, and alkaline phosphatase activity.
Explanation
Children with hypothyroidism have delayed bone age, reduced thickness of the physis, disorganization of the cartilage columns of the physis, and impaired differentiation of proliferating chondrocytes into hypertrophic cells. As a result, these children have severe growth retardation, and slipped capital femoral epiphysis may develop because of mechanical weakening of the physis. Thyroid hormone regulates terminal differentiation of the growth plate chondrocytes, with a resultant increase in type X collagen and alkaline phosphatase. These substances are important factors in matrix mineralization. Insulin-like growth factors and FGF-2 appear to act synergistically to stimulate mitotic activity of the growth plate chondrocytes. TGF-beta= and PTHrP stimulate proteoglycan synthesis and mitotic activity of the chondrocytes and inhibit type X collagen and alkaline phosphatase activity. Ballock RT: Regulation of skeletal growth and maturation by thyroid hormone, in Buckwalter JA, Ehrlich MG, Sandell LJ, Trippel SB (eds): Skeletal Growth and Development: Clinical Issues and Basic Science Advances. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1998, pp 301-317. Rosier RN, O'Keefe RJ, Reynolds PR, Hicks DG, Puzas JE: Expression and function of TGF-beta= and PTHrP in the growth plate, in Buckwalter JA, Ehrlich MG, Sandell LJ, Trippel SB (eds): Skeletal Growth and Development: Clinical Issues and Basic Science Advances. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1998, pp 285-299.
Question 1866
Topic: 4. Pediatrics
Figure 30 shows the AP radiograph of a 9-month-old girl who has been referred for evaluation of unequal leg lengths. Examination reveals symmetrical abduction of the hips. When the hips are flexed 90 degrees, the right knee height is greater than the left knee. The girth of the right thigh and calf is larger than the contralateral side. There are no cutaneous lesions, and examination of the spine is normal. The infant is moving all extremities equally and spontaneously. Management should consist of
Correct Answer & Explanation
. a renal ultrasound.
Explanation
Hemihypertrophy or hemihypotrophy is usually idiopathic, and either the leg or the entire side of the body may be involved. In the infant or young child, it is often difficult to determine which side is abnormal if the condition is mild. Because of the association of Wilms' tumor with hemihypertrophy, these patients should undergo a yearly renal ultrasound until at least age 5 years. Other conditions that may exhibit hemihypertrophy include Klippel-Trenaunay-Weber syndrome, Proteus syndrome, and neurofibromatosis. In this patient, the mild hemihypertrophy is idiopathic. Because of the normal spinal examination and absence of neurologic findings, an MRI scan is unnecessary. The absence of clinical and radiographic evidence of hip dysplasia makes both an ultrasound of the hips and application of a Pavlik harness unnecessary. Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont Ill, American Academy of Orthopaedic Surgeons, 1996, pp 185-193. Sponseller PD: Localized disorders of bone and soft tissue, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 305-344.
Question 1867
Topic: 4. Pediatrics
Figures 9a and 9b show the spinal radiographs of a 3-year-old child with short limb dwarfism. The lateral radiograph is obtained with maximal lumbar extension. Management should consist of
Correct Answer & Explanation
. close clinical follow-up.
Explanation
The patient has kyphosis in association with achondroplasia. The AP radiograph shows decreased interpedicular distance at the lower lumbar vertebrae, a feature considered to be a distinctive sign of achondroplasia. Most patients with achondroplasia have kyphosis, and this usually resolves spontaneously. When the fixed component is greater than 30 degrees, however, brace treatment is recommended. Spinal fusion is seldom required.
Question 1868
Topic: 4. Pediatrics
In a juvenile Tillaux ankle fracture, what ligament causes the displacement of the fracture fragment?
Correct Answer & Explanation
. Anterior tibiofibular
Explanation
The juvenile Tillaux ankle fracture usually occurs because the lateral half of the distal tibial physis remains open. During an external rotational force, the anterior tibiofibular ligament holds the lateral tibial epiphysis, separating it through at the junction of the middle closed physis and lateral open physis.
Question 1869
Topic: 4. Pediatrics
During stabilization of a slipped capital femoral epiphysis, the screw penetrates into the joint. The screw is repositioned so that it is within the femoral head. This transient penetration of the hip joint will most likely lead to
Correct Answer & Explanation
. no deleterious effect.
Explanation
Chondrolysis may be associated with unrecognized permanent penetration of the joint space by a pin or screw. However, transient penetration by the guide wire or screw is not associated with this problem. One study described 11 hips in which there was transient intraoperative penetration of the joint space by a guide wire or screw. These patients were followed for at least 2 years, with none showing any clinical or radiographic evidence of chondrolysis. Another retrospective study of 55 slipped epiphyses described 11 hips with transient intraoperative pin penetration, with none showing development of chondrolysis. There are no studies to suggest that transient pin penetration leads to osteonecrosis, stiffness, or premature physeal closure. Zionts LE, Simonian PT, Harvey JP Jr: Transient penetration of the hip joint during in situ cannulated-screw fixation of slipped capital femoral epiphysis. J Bone Joint Surg Am 1991;73:1054-1060.
Question 1870
Topic: Pediatric Upper Extremity & Spine
A 21-year-old right hand-dominant male collegiate swimmer reports painful clicking in the right shoulder. He states that he can occasionally feel his shoulder "slip out" when he is working out. AP, true AP, and axillary radiographs are shown in Figures 39a through 39c. What is the next most appropriate step in management?
Correct Answer & Explanation
. Physical therapy
Explanation
The radiographs show glenoid hypoplasia. The common radiographic findings of glenoid hypoplasia include an inferior and posterior glenoid deficiency, enlargement of the distal end of the clavicle, and sometimes an indentation in the glenoid. It is usually bilateral and rarely associated with other syndromes; therefore, an echocardiogram, abdominal ultrasound, or a skeletal survey is unnecessary unless the patient has stigmata of a syndrome such as Holt-Oram or Apert's. Although posterior instability has been reported, the results of glenoid osteotomy have been variable and should not be considered initially. Physical therapy is the mainstay of initial management, but the patient should be counseled that this may be a recurrent problem with early osteoarthritis developing in many patients. Radiographs of the contralateral side should be obtained because this is usually bilateral. Wirth MA, Lyons FR, Rockwood CA Jr: Hypoplasia of the glenoid: A review of sixteen patients. J Bone Joint Surg Am 1993;75:1175-1184.
Question 1871
Topic: 4. Pediatrics
A 10-year-old girl has been unable to walk for the past 5 days because of bilateral hip pain. Administration of IV morphine has provided some pain relief. She is afebrile. History reveals that she had an upper respiratory tract infection 3 weeks ago that resolved uneventfully. Examination reveals moderate pain with internal rotation and abduction, while log rolling maneuvers do not cause significant pain. An MRI scan shows a small effusion of one hip; however, a bone scan and plain radiographs are normal. Initial laboratory studies showed a markedly elevated WBC count, which subsequently declined to normal levels with IV antibiotics. Current studies show an erythrocyte sedimentation rate (ESR) of 100 mm/h. Aspiration of the hip obtains 3 mL of fluid; Gram stain is negative for bacteria, but a cell count shows a WBC count of 16,500/mm3. Streptozyme titer of the peripheral blood is 200 units (normal is less than 100 units). Management should now consist of
Correct Answer & Explanation
. discontinuation of antibiotics and administration of nonsteroidal anti-inflammatory drugs, followed by physical therapy.
Explanation
This clinical situation requires careful analysis because some data suggest infection and some a noninfectious inflammatory process. Bilateral hip involvement, the absence of significant fluid collection or fever, the streptozyme level, and the history of upper respiratory infection all suggest poststreptococcal toxic synovitis as the most likely cause for the clinical presentation. In the first 24 hours, this type of presentation might warrant incision and drainage given uncertainty of the diagnosis and the risks associated with missing an infection. However, 5 days after onset, surgery is not warranted, especially given that the patient remains afebrile and her symptoms are improving. Cardiology consultation would be appropriate. There is no evidence to suggest slipped capital femoral epiphysis. Treatment with antibiotics is not advised because there is no bacteriologic data on which to base treatment. De Cunto CL, Giannini EH, Fink CW, et al: Prognosis of children with poststreptococcal reactive arthritis. J Pediatr Infect Dis 1988;7:683-686.
Question 1872
Topic: 4. Pediatrics
A 2-year-old girl has had a swollen right knee for the past 7 weeks. There is no history of significant trauma, and she has not had a fever or been ill. Her parents report that she is stiff in the morning but otherwise does not report pain. A CBC count and erythrocyte sedimentation rate are normal. Treatment with naproxen at appropriate doses for the past 2 weeks has resulted in some improvement. Radiographs show only soft-tissue swelling. Examination reveals a healthy-appearing child with a warm and swollen right knee that is only slightly tender but lacks full extension by 20 degrees. What is the next most appropriate step in management?
Correct Answer & Explanation
. Ophthalmology consultation
Explanation
Up to 30% of children with juvenile rheumatoid arthritis (increasingly known now as juvenile idiopathic arthritis or JIA) already have potentially damaging uveitis at the time of diagnosis. This patient has typical oligoarticular JRA (JIA) and therefore is at significant risk for uveitis. MRI, radioisotope scanning, or an ACE level most likely would not provide additional useful diagnostic information because intra-articular derangement, osteomyelitis, or sarcoidosis are all unlikely. Arthrocentesis and triamcinolone hexacetonide joint injection might be indicated if continued use of nonsteroidal medication does not result in improvement, but should be held off for at least an additional 4 to 6 weeks to see if continued use of naproxen results in control of the arthritis. Wolf MD, Lichter PR, Ragsdale CG: Prognostic factors in the uveitis of juvenile rheumatoid arthritis. Ophthalmology 1987;94:1242. Cassidy JT, Petty RE: Textbook of Pediatric Rheumatology. Philadelphia, PA, WB Saunders, 2001, p 220.
Question 1873
Topic: Pediatric Hip
A 13-year-old obese male complains of left knee pain and a limp for 3 weeks. Radiographs are provided:
He is able to bear weight with crutches. During physical examination, as the affected hip is passively flexed, into which position will the limb obligately deviate?
Correct Answer & Explanation
. External rotation
Explanation
In slipped capital femoral epiphysis (SCFE), the proximal femoral epiphysis displaces posteriorly and inferiorly relative to the femoral neck. This altered anatomy leads to an obligate external rotation of the thigh during passive hip flexion, a classic physical examination finding.
Question 1874
Topic: 4. Pediatrics
A 6-week-old female infant is evaluated for clicking in her hips. An ultrasound is performed to evaluate for Developmental Dysplasia of the Hip (DDH).
What alpha angle is considered normal for a mature, appropriately formed hip on a coronal ultrasound view according to Graf's classification?
Correct Answer & Explanation
. <60 degrees
Explanation
According to Graf's classification of infant hip ultrasound, an alpha angle (measuring the bony roof of the acetabulum) of greater than 60 degrees is considered normal (Type I hip). An alpha angle between 50 and 59 degrees is physiologic immaturity (Type IIa) if the infant is <3 months old, and an angle less than 50 indicates dysplasia.
Question 1875
Topic: 4. Pediatrics
An 11-year-old obese male presents with left groin pain and an obligatory external rotation with hip flexion. Radiographs confirm a severe, stable slipped capital femoral epiphysis (SCFE). During percutaneous in situ fixation, the surgeon inadvertently places the single cannulated screw into the posterior-superior quadrant of the femoral head. Which of the following complications is most likely to occur as a direct result of this specific trajectory?
Correct Answer & Explanation
. Avascular necrosis (AVN) of the femoral head
Explanation
The blood supply to the femoral head in pediatric patients is heavily reliant on the lateral epiphyseal vessels (terminal branches of the medial femoral circumflex artery), which enter the epiphysis in the posterior-superior quadrant. Pinning in the posterior-superior quadrant significantly increases the risk of iatrogenic injury to these vessels, leading to avascular necrosis (AVN). Joint penetration is more commonly a risk with anterior-superior pin placement.
Question 1876
Topic: Pediatric Upper Extremity & Spine
A 14-year-old female presents for operative evaluation of adolescent idiopathic scoliosis. Standing full-length spine radiographs show a main thoracic curve of 55 degrees and a lumbar curve of 35 degrees. The proximal thoracic curve is 20 degrees. On side-bending radiographs, the main thoracic curve corrects to 30 degrees, the lumbar curve corrects to 15 degrees, and the proximal thoracic curve corrects to 5 degrees. Based on the Lenke classification, what is the correct curve type?
Correct Answer & Explanation
. Type 1 (Main Thoracic)
Explanation
In the Lenke classification system, a curve is considered structural if it fails to correct to < 25 degrees on side-bending radiographs or has an associated regional kyphosis > +20 degrees. Here, the lumbar curve corrects to 15 degrees (non-structural) and the proximal thoracic corrects to 5 degrees (non-structural). The main thoracic curve is the major curve (largest magnitude, 55 degrees). A major main thoracic curve with non-structural minor curves is classified as a Lenke Type 1.
Question 1877
Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a severe extension-type supracondylar humerus fracture after a fall. Radiographs classify it as a Gartland Type III. The distal fragment is severely displaced posteromedially relative to the proximal shaft. Based on this specific displacement pattern, which of the following nerve structures is at greatest risk of tethering or injury from the proximal fragment?
Correct Answer & Explanation
. Radial nerve
Explanation
In an extension-type supracondylar humerus fracture, the displacement of the distal fragment dictates the direction of the proximal spike. If the distal fragment is displaced posteromedially, the sharp proximal fragment is thrust anterolaterally, placing the radial nerve at the highest risk of injury. Conversely, if the distal fragment displaces posterolaterally, the proximal spike goes anteromedially, placing the median nerve (and AIN) at greatest risk.
Question 1878
Topic: Pediatric Hip
In the evaluation of Slipped Capital Femoral Epiphysis (SCFE), which of the following scenarios is a widely accepted indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?
Correct Answer & Explanation
. Presence of an underlying endocrine disorder, such as renal osteodystrophy
Explanation
Prophylactic pinning of the contralateral hip in a unilateral SCFE presentation is indicated in patients who are at exceptionally high risk for developing a subsequent contralateral slip. Accepted indications include the presence of endocrinopathies (such as hypothyroidism, panhypopituitarism, and renal osteodystrophy), prior radiation therapy, or young age (females < 10, males < 12) at the time of initial presentation. Bone age that is delayed (not advanced) is a risk factor.
Question 1879
Topic: 4. Pediatrics
A 3-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the left hip. At the 2-week follow-up, the parents report the child has stopped kicking the left leg. On physical examination, the left knee rests in extension and there is absent active knee extension to tactile stimulation. Which of the following harness maladjustments is the most likely cause of this complication?
Correct Answer & Explanation
. Excessive flexion of the hip
Explanation
The infant's presentation (absent active knee extension) is consistent with a femoral nerve palsy, a known complication of the Pavlik harness. Femoral nerve palsy occurs when the anterior straps are pulled too tight, causing hyperflexion of the hip which compresses the femoral nerve against the inguinal ligament. Excessive abduction of the hip (caused by overtightening the posterior straps) is associated with an increased risk of avascular necrosis (AVN) of the femoral head.
Question 1880
Topic: 4. Pediatrics
A 7-year-old boy with spastic diplegic cerebral palsy presents to the orthopedic clinic for his routine hip surveillance program. Examination reveals significant bilateral hip adductor spasticity. AP pelvis radiographs are obtained to measure the Reimers migration percentage. According to established international guidelines for hip surveillance in cerebral palsy, a migration percentage strictly above which threshold designates the hip as subluxated and generally warrants surgical intervention?
Correct Answer & Explanation
. 30%
Explanation
In children with cerebral palsy, hip surveillance is mandatory to prevent silent hip dislocation. The Reimers migration percentage measures the proportion of the ossified femoral head outside the lateral margin of the acetabulum (Perkin's line). A migration percentage >30% is universally considered the threshold for defining hip subluxation in this population. Above 30%, nonoperative measures usually fail to prevent progression, and prophylactic surgical intervention (e.g., adductor releases or varus derotational osteotomy) is strongly indicated. A migration of 100% is a complete dislocation.
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