4. Pediatrics MCQs

DISCUSSION: The child has a near complete central physeal arrest of the distal femur. She will develop worsening limb-length discrepancy. She is growing at the average rate for the population. The distal femoral physis grows roughly at a rate of 9 mm/year. Girls finish their growth roughly at 14 years. Thus, at maturity, the uninjured side will be 6.4 cm longer than the injured side. Since she has not developed an angular deformity at this point and her arrest is central, she is unlikely to develop angular deformity in any plane. REFERENCES: Little DG, Nigo L, Aiona MD: Deficiencies of current methods for the timing of epiphysiodesis. J Pediatr Orthop 1996;16:173-179. Moseley CF: Assessment and prediction in leg-length discrepancy. Instr Course Lect 1989;38:325-330.

DISCUSSION: Distal radial physeal stress syndrome has been reported in up to 25% of nonelite gymnasts showing premature closure of the distal radial physis and distal ulnar overgrowth, producing positive ulnar variance. The diagnosis should be suspected when there is tenderness at the distal radial physis in a young gymnast. The pathology is thought to be the result of repetitive compressive stresses caused by upper extremity weight-bearing forces. The recommended treatment is 3 to 6 months of rest. Salter-Harris fractures with a distal radial epiphyseal slip are unlikely, especially in the absence of a specific traumatic event.

DISCUSSION: The patient has spinal muscular atrophy, type 2. This type is intermediate in severity between the Werdnig-Hoffmann type (type 1) and the Kugelberg-Welander type (type 3). It normally manifests itself between the ages of 3 and 15 months. Survival until adolescence is common. All three types of spinal muscular atrophy have been linked to the SMN gene at the 5q12.2-13.3 locus. DNA testing is available and is preferred to muscle biopsy because it is less invasive and more definitive. REFERENCES: Biros I, Forrest S: Spinal muscular atrophy: Untangling the knot? J Med Genet 1999;36:1-8. Zerres K, Wirth B, Rudnik-Schoneborn S: Spinal muscular atrophy: Clinical and genetic correlations. Neuromuscul Disord 1997;7:202-207.

This patient likely has a physeal injury to the distal femoral physis. Stress radiographs or an MRI scan will most reliably reveal this diagnosis. The growth plate, when injured, is most commonly fractured through the hypertrophic zone of cartilage, its weakest point. This patient is optimally treated in a cylindrical or long-leg cast.

With the patient standing, add blocks under the short leg until the pelvis is level, then measure the blocks to determine the discrepancy. This method is an accurate, simple, and inexpensive way to assess limb-length discrepancy. Differences of less than 2 cm need no treatment. Increasing discrepancy in a growing child should be followed clinically. Radiographic examination can include scanography, CT scanography, or a standing pelvic radiograph with the pelvis leveled. CT scanography is the most accurate diagnostic test when hip, knee, or ankle contractures are present.

Patients with dysplasia often have a hypertrophic labrum. Abnormal contact between the femoral neck and the acetabular rim leads to labral injury, especially in the anterior-superior acetabular zone. Typically, young patients with the condition report pain with activity or long periods of sitting or driving. The hips often have limited motion, in particular in internal rotation and flexion. Forceful adduction with the maneuver causes pain.(SBQ13PE.10) Which statement is true regarding discoid menisci?Review TopicMost commonly involves the medial meniscusBilateral in >75% of casesAsymptomatic discoid meniscus should undergo saucerizationRadiographs will commonly show a hyperplastic lateral intercondylar spineRadiographs will commonly show squaring of affected condyle with cupping of tibial plateauRadiographs of knees with discoid menisci will commonly show squaring of affected condyle (lateral>medial) with cupping of tibial plateau.Discoid meniscus refers to the abnormal development of a hypertrophic and discoid shaped meniscus. It occurs in 3-5% of the population and it is considered the most common cause of a symptomatic clicking or clunking in a childs knee. The lateral meniscus is most commonly affected and it will occur bilaterally in 25% of affectedpeople. The Watanabe Classification describes the 3 types of discoid menisci. Type 1= Incomplete, Type 2 = Complete, Type 3 = Wrisberg (lack of posterior meniscotibial attachment to tibia)Kramer et al. looked at the presentation of pediatric knee pain. They showed that the lateral meniscus is more commonly affected than the medial meniscus. The majority of discoid tears occur in the posterior or middle aspect of the discoid meniscus.Lee et al. retrospectively reviewed 36 patients aged less than 15 years who underwent arthroscopic procedures for torn discoid menisci. The mean patient age at the time of surgery was 9.5 years. They showed that partial meniscectomy yielded better radiologic results than subtotal/total meniscectomy for torn discoid menisci in this population.Illustration A shows the 3 classifications of discoid menisus as originally described by Watanabe. Type 4 is a ring type discoid that was not originally described by Watanabe in his 1978 paper. Illustration B shows an AP and lateral radiograph of a discoid meniscus knee. Note squaring of affected lateral condyle in the presence of a lateral discoid meniscus. Illustration C shows 4 consecutive sagittal MRI images with meniscus continuity. It is important to note that the diagnosis of discoid menisci can be made when 3 or more 5mm sagittal images show meniscal continuity.Incorrect Answers:

DISCUSSION: 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. REFERENCES: 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. Haynes RJ: Developmental dysplasia of the hip: Etiology, pathogenesis, and examination and physical findings in the newborn. Instr Course Lect 2001;50:535-540.

This patient has undergone arthroscopic saucerization of his discoid meniscus. The indication for this procedure is treatment of a symptomatic meniscal tear. Arthroscopic treatment of lateral discoid meniscus injuries has the advantages of reducing trauma, precise resection or repair of the meniscus, and saucerization of the remaining discoid meniscus. Operative treatment is usually limited to patients with pain and mechanical symptoms that are undergoing partial meniscectomy or repair. Asymptomatic discoid meniscus without tears are not considered a surgical indication for routine saucerization.

One of the suggested causes of Perthes disease is a hypercoagulable state in a child. This would lead to thrombotic venous occlusion in the proximal femur resulting in venous hypertension and osteonecrosis of the femoral head. Therefore, look for an answer that would result in a hypercoagulable state. There is no link between hypophosphatemia or high dietary cholesterol intake and a hypercoagulable state. Elevated levels of antithrombin III would result in bleeding, not coagulation. The referenced paper demonstrated a familial occurrence in protein S and protein C deficiency and elevated levels of lipoprotein A. Protein C and S are antithrombotic factors and lipoprotein A is a thrombogenic, atherogenic lipoprotein associated with osteonecrosis in adults.

DISCUSSION: In pediatric patients who have pain and recurrent hemarthrosis in the knee, hemangioma is often seen as an internal derangement of the knee, and long delays in diagnosis are common. An MRI scan is noninvasive and will best aid in diagnosis. In this patient, the MRI scan shows a hemangioma with no evidence of meniscal injury or discoid meniscus. Hemophilia is unlikely because the patient is female. The presence of hemarthrosis makes JRA an unlikely diagnosis.

DISCUSSION: In a child with myelomeningocele, the guiding principle of treatment is to achieve a plantigrade foot by the time the child is ready to stand. The standard clubfoot protocol should be followed, but these children will require an aggressive surgical release to obtain a sufficient correction.

DISCUSSION: Malrotation of the foot is frequently overlooked in this clinical setting. This can be judged by evaluating and comparing the transmalleolar axes of the affected and unaffected legs. The rotation occurs through the physis and frequently is not recognized until the patient has been walking for a few months. The other conditions are not expected to occur in the clinical setting described. REFERENCES: Phan VC, Wroten E, Yngve DA: Foot progression angle after distal tibial physeal fractures. J Pediatr Orthop 2002;22:31-35. Brook GJ, Greer RB: Traumatic rotational displacements of the distal tibial growth plate. J Bone Joint Surg Am 1970;52:1666-1668.

DISCUSSION: The child has a Salter-Harris type IV injury involving both the growth plate and the articular surface of the ankle. This injury pattern has a high risk of physeal arrest; open reduction and internal fixation is indicated to realign the physis and joint surface. The best method of fixation to avoid growth arrest is one that does not cross the physis. This is usually achieved by an epiphyseal screw or pins parallel to the physis. If the metaphyseal fragment were large enough, a transverse metaphyseal screw could be used. The incidence of growth arrest following physeal ankle injuries is high and long-term follow-up is indicated. REFERENCES: Cass JR, Peterson HA: Salter-Harris type-IV injuries of the distal tibial epiphyseal growth plate, with emphasis on those involving the medial malleolus. J Bone Joint Surg Am 1983;65:1059-1070. Barmada A, Gaynor T, Mubarak SJ: Premature physeal closure following distal tibia physeal fractures: A new radiographic predictor. J Pediatr Orthop 2003;23:733-739.

The hockey player is suffering from commotio cordis, in which a cardiac arrhythmia occurs after a sudden blunt impact to the chest. Treatment of commotio cordis is defibrillation. As the time to defibrillation increases, the likelihood of survival decreases. In animal models, chest protectors have not shown efficacyagainst ventricular fibrillation. The velocity of the projectile (most commonly baseball, hockey puck or lacrosse ball) has also not been shown to alter survival.

DISCUSSION: A favorable prognosis can be expected in up to 70% of children with Legg-Calve-Perthes disease who are younger than age 6 years. Containment treatment has not been shown to alter the outcome in this age group. The goals of treatment in this patient are to reduce pain (synovitis), restore motion, and improve function. Symptomatic treatment modalities include bed rest, traction, crutches, activity modification, and nonsteroidal anti-inflammatory drugs. REFERENCES: Herring JA: The treatment of Legg-Calve-Perthes disease: A critical review of the literature. J Bone Joint Surg Am 1994;76:448-458. Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1996, pp 161-166.

Unwitnessed spiral fractures should raise the possibility of child abuse, especially prior to walking age. With nonaccidental trauma being considered in the differential diagnosis, a skeletal survey is indicated to determine if there are other fractures in various stages of healing.(SBQ13PE.60) If a child develops dynamic supination after treatment of idiopathic clubfoot with Ponseti casting, at what age would it be appropriate to consider transfer of the tibialis anterior tendon to the lateral dorsum of the foot?Review TopicIn the first six months of life, immediately following failed cast treatment12 months4 years12 years15 yearsTibialis tendon transfer to the dorsum of the foot should be performed to address dynamic supination when the lateral cuneiform has ossified. This is typically after at least 2 years of age and usually not before age 3.

DISCUSSION: The prognosis for most patients with Osgood-Schlatter disease is good. When the secondary ossification center unites with the main body of the tibial tubercle, the patellar tendon has a more rigid anchor, and heterotopic ossification and its associated reaction often become quiescent. However, even after closure of the growth plates, some patients have persistent symptoms. Excision of the ossicle and prominence of the tibial tuberosity decompresses the patellar tendon and allows most patients to resume sports activities. Nonsurgical modalities are ineffective. Better results have been reported after excision than after drilling of the tubercle. Excision of the ossicle is not indicated prior to skeletal maturity because symptoms will resolve in most patients when the secondary ossification center unites.

DISCUSSION: Anterolateral bowing of the tibia is normally associated with congenital pseudarthrosis of the tibia. This, in turn, is associated with neurofibromatosis. Posterior bowing is more benign and usually corrects spontaneously. However, anterolateral bowing also corrects spontaneously, and the limb-length discrepancy may be the only remaining sequela when associated with duplication of the great toe. Lisch nodules and axillary freckling are pathognomonic findings in neurofibromatosis but would not be expected in this patient because this type of tibial deformity is not associated with neurofibromatosis. REFERENCE: Weaver KM, Henry GW, Reinker KA: Unilateral duplication of the great toe with anterolateral tibial bowing. J Pediatr Orthop 1996;16:73-77.

DISCUSSION: The growth plate in the distal femur has an undulating topography, with prominences called mammillary bodies that interdigitate with other portions of the physis to provide stability at the distal femur. A typical distal femoral physeal fracture propagates through multiple layers of the growth plate as opposed to most Salter-Harris type I physeal fractures. REFERENCES: Smith DG, Geist RW, Cooperman DR: Microscopic examination of a naturally occurring epiphyseal plate fracture. J Pediatr Orthop 1985;5:306-308. Jaramillo D, Kammen BF, Shapiro F: Cartilaginous path of physeal fracture separations: Evaluation with MR imaging: An experimental study with histologic correlation in rabbits. Radiology 2000;215:504-511.

A type II injury consists of a fracture along the hypertrophic zone of the growth plate with an attached metaphyseal bony fragment. The hypertrophic zone is the metaphyseal fragment and is located on the compressive or concave side, whereas periosteum is torn on the tensile or convex side. The reserve and proliferative zones remain with the epiphysis and the circulation is usually preserved.