Kristen L. Carroll

Outcomes of External fixation of pediatric femoral shaft fractures

Thirty-seven femoral shaft fractures, in 33 patients, were treated with unilateral external fixation after reduction from 1992 through 1998. Ten girls and 23 boys ranged in age from 4 to 14 years. Thirteen children had multiple injuries, whereas 20 children had isolated fractures. Average follow-up was 3 years, 9 months, with only five children lost to follow-up. The average duration in fixator was 107 days. Thirty-six of 37 fractures healed, and there was one delayed union. There was minimal angulation, and limb-length inequality was generally <1 cm; 72.7% had pin-tract infections. Eight (21.6%) patients refractured; four occurred in the four patients with bilateral femur fractures. We agree with previous reports that external fixation remains a viable option for treatment of pediatric femoral shaft fractures. However, in our series, rate of refracture (21.6%) after removal of the external fixator is significantly higher than previously reported in literature. Children with bilateral femur fractures were at greatest risk.

Clinical correlation to genetic variations of hereditary multiple exostosis.

Hereditary multiple exostosis (HME) is an autosomal dominant disorder leading to polyostotic periphyseal osteochondroma formation. These tumorous lesions can cause growth disturbances, painful local symptoms, restriction of joint motion, and neurologic compromise. Malignant transformation has been noted. The reports of the incidence of these complications vary widely in the literature. Recently, genetic lineage mapping disclosed three locations for HME with loci on chromosomes 8, 11, and 19. It is possible that these three genotypes may result in different phenotypic expression of HME and thus explain the variable manifestations of the disease. This study attempts to record the clinical findings of HME patients who have undergone genetic mapping to determine whether varying clinical patterns may exist for each genotype of HME.

Coxa vara : Surgical outcomes of valgus osteotomies

Since the 1950s, valgus-producing femoral osteotomy has been the preferred treatment for significant coxa vara. Despite well-performed surgeries, the literature cites recurrence rates of 30-70%. The present study reviews our past 15 years of surgical experience for coxa vara; 26 children with 37 affected hips were retrospectively evaluated for outcome following valgus osteotomy. Both congenital and acquired types of coxa vara were included. Overall recurrence rate following valgus osteotomy was 50%. Age at time of surgery, type of surgery, and type of implant and etiology were found to have no bearing on recurrence. However, if Hilgenreiners epiphyseal angle was corrected to < 38 degrees, 95% of children had no recurrence of varus. In contrast, head-shaft angle was found not to be a reliable indicator of appropriate correction. Only six of 37 hips required pelvic osteotomy (five Pemberton, one Chiari) for dysplasia, and four of these had developmental dysplasia of the hip as the underlying etiology for their coxa vara. However, if the proximal femur was corrected and maintained before age 10, 83% of children had excellent acetabular depth, spherical congruency, relief from pain, and correction of Trendelenburg gait at latest follow-up.

A Prospective Evaluation of the Clinical Presentation of Pediatric Pelvic Fractures

BACKGROUND We sought to describe pediatric, blunt trauma patients with pelvic fracture (PF) and to evaluate pelvis examination sensitivity and specificity. METHODS We conducted a prospective study of blunt trauma patients at a Level I pediatric trauma center. A pediatric emergency medicine physician attempted to diagnose a PF, solely on the basis of the history and pelvis examination. Patients with blunt trauma but no pelvic fracture (NPF) were used as controls. RESULTS We enrolled 140 patients (16 PF, 124 NPF), and no significant differences were found regarding median age, gender, injury mechanism, acuity, and medical outcome. Approximately 25% of PF patients had iliac-wing fractures; 37%, single pelvic ring; 25%, double pelvic ring; and 13%, acetabular fractures. Eleven patients with PF had an abnormal pelvis examination (69% sensitivity), compared with six NPF patients (95% specificity, negative predictive value 0.91). CONCLUSION Pediatric patients with PF have low mortality and few complex fractures. The pelvis examination appears to have both high specificity and negative predictive value.

Pemberton Pericapsular Osteotomy to Treat a Dysplastic Hip in Cerebral Palsy

We reviewed the results of Pemberton pericapsular osteotomy in nineteen hips (fifteen patients) that were subluxated (fifteen hips) or dislocated (two hips) or had severe acetabular dysplasia (two hips) secondary to spastic cerebral palsy. At least one concomitant procedure was performed in fifteen hips. These procedures included an intertrochanteric osteotomy to correct excessive femoral anteversion or valgus deformity of the neck-shaft angle (thirteen hips), a soft-tissue release (nine hips), and an open reduction (three hips). Four hips had no concomitant procedure. Five of the nineteen hips were painful preoperatively. The average age of the patients at the time of the index operation was seven years and nine months (range, three years and five months to twelve years and three months). The average duration of follow-up was ten years and nine months (range, three years and one month to nineteen years and nine months). All osteotomy sites healed without complications. At the latest follow-up examination, all of the hips were pain-free and satisfactorily reduced and none of the patients had deterioration in function. The average center-edge angle was -5 degrees (range, -45 to 18 degrees) preoperatively and 38 degrees (range, 17 to 53 degrees) at the latest follow-up examination. The average migration index of Reimers was 55 per cent (range, 30 to 100 per cent) preoperatively compared with 12 per cent (range, 0 to 46 per cent) at the latest follow-up examination. Sixteen of the nineteen hips were followed until closure of the triradiate cartilage. There were no instances of posterior uncovering or osteonecrosis of the femoral head or premature closure of the triradiate physeal cartilage leading to deficient acetabular coverage. Our results suggest that good clinical and radiographic results can be achieved with the Pemberton pericapsular osteotomy, with simultaneous intertrochanteric osteotomy and soft-tissue release when indicated, as treatment for subluxation or dislocation of the hip or acetabular dysplasia in cerebral palsy.

Surgical release of tethered spinal cord : Survivorship analysis and orthopedic outcome

Between January 1988 and February 1995, 133 tethered spinal cord-release procedures in 88 consecutive patients were performed at our institution and were used to determine survivorship data for surgical release of tethered spinal cord. The diagnoses included spinal dysraphism (67), achondroplasia (nine), isolated tethered cord (nine), cerebral palsy (three), and others (seven). Survivorship data were calculated for the initial and first-revision tethered cord release. There was a 50% revision rate by 5 years after initial tethered-cord release and a 57% revision rate by 2 years after a second release. Thirty-six patients were excluded for having <2 years of clinical follow-up, leaving 97 spinal cord releases in 52 patients available for outcome analysis. At a mean follow-up of 4.4 years (range, 2-11.3), 58% of patients required one or more orthopedic procedures after tethered-cord release. The average number of orthopedic procedures per year before release (0.28/year) was found to increase after initial release (0.39/year; p < 0.05). These data demonstrate the frequent need for operative revision after index tethered-cord release, especially in children with spinal dysraphism. In addition, the need for orthopedic procedures after tethered spinal-cord release frequently persists.

Use of allografts in Pemberton osteotomies

Twenty patients treated with 26 Pemberton osteotomies with allograft bone wedges were retrospectively evaluated radiographically. Two patients undergoing four osteotomies were excluded because of incomplete records or <1 year of follow-up. Eleven of the remaining 18 patients had other procedures performed. Osteotomies all united radiographically within 3 months. The acetabular index improved from 33° before surgery to 18° after surgery, and the lateral migration index improved from 60% to 26%. This new technique of Pemberton osteotomy with patellar allograft wedges allows good correction of acetabular dysplasia with immediate graft stability. This stability often obviates the need for postoperative spica casting, even for patients undergoing bilateral procedures, thereby allowing more rapid rehabilitation.

Long-term follow-up of open reduction surgery for developmental dislocation of the hip.

Background: We posed 2 questions: what is the long-term result of open reduction surgery in developmental dysplasia of the hip, and is there an age at surgery above which the outcome was too poor to recommend the operation? Methods: Between 1955 and 1995, 148 patients with 179 dislocated hips had open reduction surgery for developmental dysplasia of the hip (141 anterior and 38 Ludloff medial approaches). We attempted to locate all 148 patients for the follow-up evaluation. Results: Fifty-three patients (36%) with 66 hips (37%) were located and participated in the study. These 66 hips represented 34% of the anterior open reductions and 47% of the Ludloff medial reductions. Twenty-two of the 66 hips had Severin IV or worse outcomes and included 7 with total hip arthroplasties and 2 with hip fusions. Age at surgery was significantly lower for Severin I, II, and III, compared with Severin IV and above (P=0.003, 0.001, 0.003) with outcomes deteriorating substantially after age 3. Approximately half of the hips required further surgery for dysplasia. All hips that sustained osseous necrosis had Severin IV or worse outcomes, and hips that redislocated and required revision surgery only achieved Severin I or II ratings 18% of the time. Nine “normal” hips became dysplastic and 3 had pelvic osteotomies as teenagers. Two other normal hips developed osseous necrosis during treatment of the contralateral hip. Conclusions: Results deteriorate as the age at surgery increases. Osseous necrosis and redislocation predict a poor functional and radiographic result. The “normal” hip may develop insidious dysplasia and also may be injured during treatment of the involved hip. Above age 3, some patients may not have sufficient acetabular growth to remodel a surgically reduced hip. Level of Evidence: Level IV—case series.

Measurement of the center edge angle and determination of the Severin classification using digital radiography, computer-assisted measurement tools, and a Severin algorithm: intraobserver and interobserver reliability revisited.

Background Numerous studies underscore the poor intraobserver and interobserver reliability of both the center edge angle (CEA) and the Severin classification using plain film measurements. In this study, experienced observers applied a computer-assisted measurement program to determine the CEA in digital pelvic radiographs of adults who had been previously treated for dysplasia of the hip (DDH). Using a teaching aid/algorithm of the Severin classification, the observers then assigned a Severin rating to these hips. Intraobserver and interobserver errors were then calculated on both the CEA measurements and the Severin classifications. Methods Four pediatric orthopaedic surgeons and 1 pediatric radiologist calculated the CEAs using the OrthoView TM planning system and then determined the Severin classification on 41 blinded digital pelvic radiographs. The radiographs were evaluated by each examiner twice, with evaluations separated by 2 months. All examiners reviewed a Severin classification algorithm before making their Severin assignments. The intraobserver and interobserver reliability for both the CEA and the Severin classification were calculated using the interclass correlation coefficients and Cohen and Fleiss &kgr; scores, respectively. Results The intraobserver and interobserver reliability for CEA measurement was moderate to almost perfect. When we separated the Severin classification into 3 clinically relevant groups of good (Severin I and II), dysplastic (Severin III), and poor (Severin IV and above), our interobserver reliability neared almost perfect. Conclusion The Severin classification is an extremely useful and oft-used radiographic measure for the success of DDH treatment. Our research found digital radiography, computer-aided measurement tools, the use of a Severin algorithm, and separating the Severin classification into 3 clinically relevant groups significantly increased the intraobserver and interobserver reliability of both the CEA and Severin classification. This finding will assist future studies using the CEA and Severin classification in the radiographic assessment of DDH treatment outcomes. Level of Evidence Diagnostic Studies-Investigating a Diagnostic Test, Level 1

Unsuspected osteochondroma-like outgrowths in the cranial base of Hereditary Multiple Exostoses patients and modeling and treatment with a BMP antagonist in mice

Hereditary Multiple Exostoses (HME) is a rare pediatric disorder caused by loss-of-function mutations in the genes encoding the heparan sulfate (HS)-synthesizing enzymes EXT1 or EXT2. HME is characterized by formation of cartilaginous outgrowths—called osteochondromas- next to the growth plates of many axial and appendicular skeletal elements. Surprisingly, it is not known whether such tumors also form in endochondral elements of the craniofacial skeleton. Here, we carried out a retrospective analysis of cervical spine MRI and CT scans from 50 consecutive HME patients that included cranial skeletal images. Interestingly, nearly half of the patients displayed moderate defects or osteochondroma-like outgrowths in the cranial base and specifically in the clivus. In good correlation, osteochondromas developed in the cranial base of mutant Ext1f/f;Col2-CreER or Ext1f/f;Aggrecan-CreER mouse models of HME along the synchondrosis growth plates. Osteochondroma formation was preceded by phenotypic alteration of cells at the chondro-perichondrial boundary and was accompanied by ectopic expression of major cartilage matrix genes -collagen 2 and collagen X- within the growing ectopic masses. Because chondrogenesis requires bone morphogenetic protein (BMP) signaling, we asked whether osteochondroma formation could be blocked by a BMP signaling antagonist. Systemic administration with LDN-193189 effectively inhibited osteochondroma growth in conditional Ext1-mutant mice. In vitro studies with mouse embryo chondrogenic cells clarified the mechanisms of LDN-193189 action that turned out to include decreases in canonical BMP signaling pSMAD1/5/8 effectors but interestingly, concurrent increases in such anti-chondrogenic mechanisms as pERK1/2 and Chordin, Fgf9 and Fgf18 expression. Our study is the first to reveal that the cranial base can be affected in patients with HME and that osteochondroma formation is amenable to therapeutic drug intervention.