Kenneth J. Noonan

Background: The aim of this study was to determine if radiographic measurements, taken before tenotomy, can predict outcome in children with idiopathic clubfoot treated by the Ponseti method. Methods: A retrospective chart and radiographic review was performed on children with idiopathic clubfoot treated with the Ponseti method over a 10-year period with minimum 2-year follow-up that had a forced dorsiflexion lateral foot radiograph before tenotomy. All angles were measured in duplicate on the pretenotomy radiographs, including: foot dorsiflexion (defined as the 90 minus the angle between the tibial shaft and a plastic plate used to dorsiflex the foot), tibio-calcaneal, talo-calcaneal, and talo-first metatarsal angles. Clinical review of patient records identified different patient outcomes: no additional treatment required, relapse (additional casting and/or surgery required), recurrence (any additional surgery required), or reconstruction (surgery not including repeat tenotomy). Results: Forty-five patients (71 feet) were included in the study. The median age at follow-up was 4.6 years. The intrareader reliability was acceptable for all measures. Thirteen of the 71 (18%) feet required additional surgery, occurring at a median age of 3.6 years. Of the 4 radiographic measures, only pretenotomy foot dorsiflexion predicted recurrence (hazard ratio=0.96, P=0.03). Youden’s method identified 16.6 degrees of dorsiflexion as the optimal cutoff. Feet with at least that amount of dorsiflexion pretenotomy (n=21) experienced no recurrences; feet with less than that amount of dorsiflexion (n=50) experienced 13 recurrences (P=0.007). Conclusions: Reduced foot dorsiflexion on lateral forced dorsiflexion pretenotomy radiograph was associated with an increased risk of recurrence. Radiographic dorsiflexion to 15 degrees past neutral before tenotomy appears to predict successful treatment via the Ponseti method. Level of Evidence: Level IV.

Introduction: It is common for pediatric patients with a history of hip dysplasia to undergo anteroposterior (AP) and frog-leg (FL) lateral radiographs to monitor development of the hip. Because of sensitivity of pediatric tissues to ionizing radiation, we sought to document the relationship between AP and FL radiographs and to determine which image was better to assess acetabular dysplasia. Methods: An Institutional Review Board–approved, retrospective review was conducted on 33 patients screened for hip dysplasia at a single institution. We sought to determine whether either film was more likely to be qualitatively better in position and whether there were differences in acetabular measures between the 2 radiographs. Standard measurements on AP and FL radiographs were made by 5 observers on 2 different occasions to assess interobserver and intraobserver variability. Results: The mean age was 23+1 months, and 80% were female; none of the children had hip dysplasia. There was no statistical significance in the quotient of pelvic rotation (AP 1.2+0.1 degrees and FL 1.1+0.1 degrees; P=0.84). There was a statistical difference in obturator height in mm (AP 16.0+0.3 and FL 17.8+0.2; P=7.2E−10). The mean intraobserver variability for the acetabular index was 1.8+0.2 and 1.7+0.2 degrees for AP and FL alignments, respectively (P=0.58), and the mean interobserver variability was 1.7+0.1 and 1.7+0.1 degrees, respectively (P=0.75). The measurements of linear variability between the AP and FL showed no statistical significant difference with the exception of the left Hilgenreiner distance in mm (AP 1.00+0.08 and FL 0.81+0.08; P=0.02). Discussion: These results demonstrate that there is little clinical difference in variability of positioning and rotational variables between AP and FL radiographs for hip dysplasia. These results indicate that either image could be used assess to acetabular dysplasia thus decreasing risks of ionizing radiation. Level of Evidence: Level III.

### Developmental Dysplasia of the Hip A prospective randomized trial evaluating immediate treatment compared with active sonographic surveillance for infants with dysplastic, nondislocatable hips demonstrated that surveillance halved the need for treatment without having an effect on the radiographic appearance of the hip at the age of one year1. In a study in which twenty-nine patients with bilateral dislocation of the hip were compared with thirty-eight patients with unilateral dislocation, there was no significant difference between the two groups with regard to the failure of Pavlik treatment2. Two studies analyzed factors associated with unsuccessful Pavlik harness treatment of dislocated hips3,4. In one series of 221 hips, successful reduction was obtained in 81.9% of the hips, with development of osteonecrosis in 8.8%3. Adduction contracture and decreased distance from the proximal medial femoral metaphysis (indicated by the “a” line) were identified as risk factors that were predictive of failure. Another study of eighty-five patients demonstrated a rate of Pavlik harness failure of 37%4. Sonographic findings associated with unsuccessful Pavlik harness treatment included an increased beta angle, superior femoral head migration relative to the labrum, and total femoral head displacement less than −30°4. In a retrospective review of late-presenting patients (age range, six to twenty-four months) who were managed with Pavlik harness reduction, 60% of Graf type-3 hips were reduced with no associated osteonecrosis, whereas no Graf type-4 hips were reduced5. A single-institution review of operative reduction of dislocated hips in late-presenting children demonstrated that femoral shortening osteotomy was more common in children with an age of more than thirty-six months or with femoral displacement of >30% of the pelvic height, with an overall prevalence of 35%6. In the study by Spence et al., open reduction combined with varus derotational proximal …

Background: The fluoroquinolones are a relatively new class of antimicrobials with an appealing spectrum of activity. Their use in pediatric medicine is limited because of the concern over possible growth inhibition, as published reports have documented articular cartilage damage in animal models after their administration. These data, extrapolated to include the epiphyseal cartilage, suggest that these agents may reduce growth rates, but limited human data are at the least equivocal, if not strictly contradictory to such claims. Specific investigations into the effects of fluoroquinolones on epiphyseal plate cartilage and growth velocity have not been performed. Methods: Gatifloxacin and ciprofloxacin were used as representative agents of the fluoroquinolone class. Each drug was administered to experimental lambs over a 14-day interval at a dose designed to reflect those used in pediatric medicine. Recumbent versus standing intervals were used to monitor for arthropathy. Upon completion of fluoroquinolone administration, lambs underwent double fluorochrome labeling for determination of growth velocity. Gross and microscopic analysis of articular cartilage was performed to assess for pathologic changes. Age- and sex-matched lambs served as controls. Results: Neither gatifloxacin nor ciprofloxacin negatively affected growth velocity of the proximal tibial growth plate as measured by double fluorochrome labeling. In addition, no difference between experimental and control lambs in regard to recumbent versus standing intervals was noted. Examination of the articular cartilage failed to suggest chondrotoxicity. Conclusion: Fluoroquinolone antimicrobials do not affect growth velocity in the ovine model when administered along a dosing regimen that closely models that seen in pediatric medicine. Clinical Relevance: Fluoroquinolones may be acceptable for use in the pediatric population, as concerns over chondrotoxicity and growth inhibition may not be valid. These data suggest that expanded studies in lambs and other species, including humans, with differences in dosing and duration are justified to ultimately demonstrate clinical safety.

Distraction osteogenesis is a highly successful method of bone formation, yet muscle fibrosis and contractures can result in significant morbidity. In the current study, we investigate the efficacy of botulinum toxin A in preventing fibrosis and potentially increasing muscle development in distracted muscles. Fifteen New Zealand White rabbits underwent tibial distraction at 1.5 mm/day until a 20% gain was achieved. Treatment groups were divided by drug (saline or botulinum toxin) and target muscle (gastrocnemius or tibialis anterior). Two additional control animals received no treatment. Bromeodeoxyuridine was delivered continuously throughout the 8‐week experiment, and following muscle harvest. Tissues were stained for BrdU, Pax‐7, vimentin, and haematoxylin and eosin staining. Mitotic activity increased in all distracted animals; however, in the animals receiving botulinum toxin A injections into the gastrocnemius, the antagonist tibialis anterior suffered up to 9% less fibrosis than distraction alone (p = 0.024). Use of botulinum A toxin did not appear to promote or improve neogenesis of muscle fibers, nor did it decrease fibrosis in the injected muscles. It appears from this study, and a previously published study on the effects of this toxin on muscle function, that botulinum A toxin maybe of some benefit in decreasing morbidity in the antagonist muscle but not the muscle injected with the toxin. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:310–317, 2009

Purpose: Our current understanding of the rate and pattern of physeal closure is based on roentgenographic, magnetic resonance imaging, and qualitative histological studies. The purpose of this report is to provide a detailed histomorphometric/stereological analysis of a distal tibial human growth plate in the process of physiological epiphysiodesis. Methods: A human distal tibial growth plate was sampled in three regions (anterior, central, and posterior), with each region further separated medially, in the middle, and laterally. The regions were assessed for the location and extent of bony bar formation as well as for physeal height. Companion sections from optimally fixed tissue in the distal 100 µm of the hypertrophic zone were analyzed for hypertrophic chondrocytic volumes. Results: Physis closure started in the middle of the central region of the growth plate, with 46% of the volume in this area occupied by trans-physeal bridging bone. The growth plate was also narrowed with the lowest physeal heights evident in the middle of the central and anterior regions of the physis. Disruption of the regular columns of the physis was evident with the cells arranged in clusters with intervening areas of acellularity. The average hypertrophic cell volume was 5,900 µm³ and did not significantly differ between different areas of the physis. Conclusions: This is the first characterization of closure in a human distal tibial growth plate via optimum fixation and stereological techniques. The studied physis was during the earliest phases of closure and provides stereological support that the distal tibial physis closes in a central to medial direction.

Background: Thermal injuries caused by application of casts continue to occur despite the development of newer cast materials. We studied the risk of these injuries with contemporary methods of immobilization.

Background: Thermal injuries caused by application of casts continue to occur despite the development of newer cast materials. We studied the risk of these injuries with contemporary methods of immobilization.

Blount disease is a deformity of the knee as a result of abnormal mechanical forces known to influence the growth of the physis. Despite existing studies on mechanical forces on chondrocyte cultures or limited growth plate specimens, very little information characterizes the whole growth plate to asymmetrical loading. In this study, we evaluate the response of 5 ovine proximal tibial growth plates to asymmetrical mechanical loading. Fresh proximal tibia specimens were mounted, and compressive forces were applied via a servohydraulic test frame (MTS Systems Corporation, Minneapolis, Minn) machine at standardized locations while transducers recorded the displacement at different locations. With this method, we demonstrate that loading (cyclical or static) on 1 edge of the tibial surface results in compression through the physis under the site of pressure. In addition, we record statistically significant tensile displacement opposite the compressed side (P < 0.001); this effect diminished as loading cell moved central on the tibial surface. We further show that growth plate topography influences the amount of tension and compression observed. From this study, we conclude that asymmetrical loading (such as that observed in Blount disease) may lead to compression (which retards growth) but also develops tension on the convex side (which may be a mechanism to increase deformity via Depelch phenomenon). The relationship of physeal architecture (more undulations-less physeal strain) may explain why greater deformity is observed on the tibial side of the knee in adolescent Blount disease than on the femoral side.