Intrarater and Interrater Reliability of Radiographic Characteristics in Skeletally Immature Patients With Anterior Cruciate Ligament Tears: A PLUTO Study Group Reliability Study.

BACKGROUND: Radiographic measurements of limb alignment in skeletally immature patients with anterior cruciate ligament (ACL) tears are frequently used for surgical decision-making, preoperative planning, and postoperative monitoring of skeletal growth. However, the interrater and intrarater reliability of these radiographic characteristics in this patient population is not well documented. HYPOTHESIS: Excellent reliability across 4 raters will be demonstrated for all digital measures of length, coronal plane joint orientation angles, mechanical axis, and tibial slope in skeletally immature patients with ACL tears. STUDY DESIGN: Cohort study (diagnosis). METHODS: Three fellowship-trained orthopaedic surgeons and 1 medical student performed 2 rounds of radiographic measurements on digital imaging (lateral knee radiographs and long-leg radiographs) of skeletally immature patients with ACL tears. Intrarater and interrater reliability for continuous radiographic measurements was assessed with intraclass correlation coefficients (ICCs) across 4 raters with 95% CIs for affected and unaffected side measurements. Interrater reliability analysis used an ICC (2, 4) structure and intrarater reliability analysis used an ICC (2, 1) structure. A weighted kappa coefficient was calculated for ordinal variables along with 95% CIs for both interrater and intrarater reliability. Agreement statistic interpretations are based on scales described by Fleiss, and Cicchetti and Sparrow: <0.40, poor; 0.40 to 0.59, fair; 0.60 to 0.74, good; and >0.74, excellent. RESULTS: Radiographs from a convenience sample of 43 patients were included. Intrarater reliability was excellent for nearly all measurements and raters. Interrater reliability was also excellent for nearly all reads for all measurements. CONCLUSION: Radiographic reliability of long-leg radiographs and lateral knee x-rays in skeletally immature children with ACL tears is excellent across nearly all measures and raters and can be obtained and interpreted as reliable and reproducible means to measure limb length and alignment. LEVEL OF EVIDENCE: Level III.

Differential DNA methylation and transcriptional signatures characterize impairment of muscle stem cells in pediatric human muscle contractures after brain injury.

Limb contractures are a debilitating and progressive consequence of a wide range of upper motor neuron injuries that affect skeletal muscle function. One type of perinatal brain injury causes cerebral palsy (CP), which affects a child's ability to move and is often painful. While several rehabilitation therapies are used to treat contractures, their long-term effectiveness is marginal since such therapies do not change muscle biological properties. Therefore, new therapies based on a biological understanding of contracture development are needed. Here, we show that myoblast progenitors from contractured muscle in children with CP are hyperproliferative. This phenotype is associated with DNA hypermethylation and specific gene expression patterns that favor cell proliferation over quiescence. Treatment of CP myoblasts with 5-azacytidine, a DNA hypomethylating agent, reduced this epigenetic imprint to TD levels, promoting exit from mitosis and molecular mechanisms of cellular quiescence. Together with previous studies demonstrating reduction in myoblast differentiation, this suggests a mechanism of contracture formation that is due to epigenetic modifications that alter the myogenic program of muscle-generating stem cells. We suggest that normalization of DNA methylation levels could rescue myogenesis and promote regulated muscle growth in muscle contracture and thus may represent a new nonsurgical approach to treating this devastating neuromuscular condition.

Contribution of extracellular matrix components to the stiffness of skeletal muscle contractures in patients with cerebral palsy.

Purpose: Joint contractures in children with cerebral palsy contain muscle tissue that is mechanically stiffer with higher collagen content than typically developing children. Interestingly, the correlation between collagen content and stiffness is weak. To date, no data are available on collagen types or other extracellular matrix proteins in these muscles, nor any information regarding their function. Thus, our purpose was to measure specific extracellular protein composition in cerebral palsy and typically developing human muscles along with structural aspects of extracellular matrix architecture to determine the extent to which these explain mechanical properties. Materials and Methods: Biopsies were collected from children with cerebral palsy undergoing muscle lengthening procedures and typically developing children undergoing anterior cruciate ligament reconstruction. Tissue was prepared for the determination of collagen types I, III, IV, and VI, proteoglycan, biglycan, decorin, hyaluronic acid/uronic acid and collagen crosslinking. Results: All collagen types increased in cerebral palsy along with pyridinoline crosslinks, total proteoglycan, and uronic acid. In all cases, type I or total collagen and total proteoglycan were positive predictors, while biglycan was a negative predictor of stiffness. Together these parameters accounted for a greater degree of variance within groups than across groups, demonstrating an altered relationship between extracellular matrix and stiffness with cerebral palsy. Further, stereological analysis revealed a significant increase in collagen fibrils organized in cables and an increased volume fraction of fibroblasts in CP muscle. Conclusions: These data demonstrate a novel adaptation of muscle extracellular matrix in children with cerebral palsy that includes alterations in extracellular matrix protein composition and structure related to mechanical function.

Skeletal muscle maximal mitochondrial activity in ambulatory children with cerebral palsy.

AIM: To compare skeletal muscle mitochondrial enzyme activity and mitochondrial content between independently ambulatory children with cerebral palsy (CP) and typically developing children. METHOD: Gracilis biopsies were obtained from 12 children during surgery (n=6/group, children with CP: one female, five males, mean age 13y 4mo, SD 5y 1mo, 4y 1mo-17y 10mo; typically developing children: three females, three males, mean age 16y 5mo, SD 1y 4mo, 14y 6mo-18y 2mo). Spectrophotometric enzymatic assays were used to evaluate the activity of mitochondrial electron transport chain complexes. Mitochondrial content was evaluated using citrate synthase assay, mitochondrial DNA copy number, and immunoblots for specific respiratory chain proteins. RESULTS: Maximal enzyme activity was significantly (50-80%) lower in children with CP versus typically developing children, for complex I (11nmol/min/mg protein, standard error of the mean [SEM] 1.7 vs 20.7nmol/min/mg protein, SEM 4), complex II (6.9nmol/min/mg protein, SEM 1.2 vs 21nmol/min/mg protein, SEM 2.7), complex III (31.9nmol/min/mg protein, SEM 7.4 vs 72.7nmol/min/mg protein, SEM 7.2), and complex I+III (7.4nmol/min/mg protein, SEM 2.5 vs 31.8nmol/min/mg protein, SEM 9.3). Decreased electron transport chain activity was not the result of lower mitochondrial content. INTERPRETATION: Skeletal muscle mitochondrial electron transport chain enzymatic activity but not mitochondrial content is reduced in independently ambulatory children with CP. Decreased mitochondrial oxidative capacity might explain reported increased energetics of movement and fatigue in ambulatory children with CP. What this paper adds Skeletal muscle mitochondrial electron transport chain enzymatic activity is reduced in independently ambulatory children with cerebral palsy (CP). Mitochondrial content appears to be similar between children with CP and typically developing children.

Comparison of Staged Versus Same-day Bilateral Hip Surgery in Nonambulatory Children With Cerebral Palsy.

BACKGROUND: Bilateral hip reconstructions with osteotomies are commonly required in patients with severe cerebral palsy (CP) and dysplasia. These procedures can be performed by staging each hip surgery, separated by weeks to months, or by addressing both hips in a single-event surgery. The optimal timing of such surgery is yet to be determined. The purpose of this study was to retrospectively compare major complications between the staged and single-event approaches. METHODS: Medical records of patients who underwent bilateral hip osteotomies, with at least one side including a pelvic osteotomy, were retrospectively reviewed. Subjects were identified who had a diagnosis of nonambulatory CP (defined by Gross Motor and Functional Classification System level IV or V), and at least 1 year of clinical follow-up. All hips were treated by 1 of 7 surgeons: 2 surgeons who always performing single-event surgery and 5 who always perform staged surgeries. Complications were stratified by the Modified Clavien-Dindo Classification (grades 1 to 5). The primary outcome was major complications (grade ≥3), while minor complications, readmissions, reoperations, and resource utilization outcomes were investigated secondarily. RESULTS: Sixty-five patients met our inclusion criteria: 35 received single-event surgery and 30 received staged surgery. The staged group had a higher rate of major complications per patient (0.30 vs. 0; P=0.013). Unplanned readmissions and reoperations were likewise increased in the staged group. Minor complication rates were high in both groups, with no differences observed between staged and single-event approaches (3.27 per patient vs. 2.91; P=0.952). There were no complications causing permanent disability or death. The total length of stay (6.2 vs. 4.0 d; P<0.001) and mean nonsurgical operating room time (65.7 vs. 45.6 min; P<0.001) were increased in the staged group versus the single-event group. CONCLUSIONS: The staged approach to bilateral hip reconstructions in the nonambulatory CP population was associated with a higher rate of major complications compared with a single-event approach. Minor complications were similar for both approaches. Both approaches can have an acceptable safety profile with no observed grade 4 or 5 complications. LEVEL OF EVIDENCE: Level III.

The Natural History of Meniscus Tears.

BACKGROUND: In order to determine whether treatments are effective in the treatment of meniscus tears, it is first necessary to understand the natural history of meniscus tears. The purpose of this paper is to review the literature to ascertain the natural history of meniscus tears in children and adolescents. METHODS: A search of the Pubmed and Embase databases was performed using the search terms "meniscus tears," "natural history of meniscus tears," "knee meniscus," "discoid meniscus," and "natural history of discoid meniscus tears." RESULTS: A total of 2567 articles on meniscus tears, 28 articles on natural history of meniscus tears, 8065 articles on "menisci," 396 articles on "discoid meniscus," and only 2 on the "natural history of discoid meniscus" were found. After reviewing the titles of these articles and reviewing the abstracts of 237 articles, it was clear that there was little true long-term natural history data of untreated meniscus tears nor whether treating meniscus tears altered the natural history. Twenty-five articles were chosen as there was some mention of natural history in their studies. CONCLUSIONS: There are few long-term data on untreated meniscal tears or discoid meniscus, or tears in children and adolescents. The literature suggests that there is a higher incidence of chondral injury and subsequent osteoarthritis, but there are many confounding variables which are not controlled for in these relatively short-term papers.

Loss of myogenic potential and fusion capacity of muscle stem cells isolated from contractured muscle in children with cerebral palsy.

Cerebral palsy (CP) is the most common cause of pediatric neurodevelopmental and physical disability in the United States. It is defined as a group of motor disorders caused by a nonprogressive perinatal insult to the brain. Although the brain lesion is nonprogressive, there is a progressive, lifelong impact on skeletal muscles, which are shorter, spastic, and may develop debilitating contractures. Satellite cells are resident muscle stem cells that are indispensable for postnatal growth and regeneration of skeletal muscles. Here we measured the myogenic potential of satellite cells isolated from contractured muscles in children with CP. When compared with typically developing (TD) children, satellite cell-derived myoblasts from CP differentiated more slowly (slope: 0.013 (SD 0.013) CP vs. 0.091 (SD 0.024) TD over 24 h, P < 0.001) and fused less (fusion index: 21.3 (SD 8.6) CP vs. 81.3 (SD 7.7) TD after 48 h, P < 0.001) after exposure to low-serum conditions that stimulated myotube formation. This impairment was associated with downregulation of several markers important for myoblast fusion and myotube formation, including DNA methylation-dependent inhibition of promyogenic integrin-ß 1D (ITGB1D) protein expression levels (-50% at 42 h), and ~25% loss of integrin-mediated focal adhesion kinase phosphorylation. The cytidine analog 5-Azacytidine (5-AZA), a demethylating agent, restored ITGB1D levels and promoted myogenesis in CP cultures. Our data demonstrate that muscle contractures in CP are associated with loss of satellite cell myogenic potential that is dependent on DNA methylation patterns affecting expression of genetic programs associated with muscle stem cell differentiation and muscle fiber formation.

Risk Factors for Early ACL Reconstruction Failure in Pediatric and Adolescent Patients: A Review of 561 Cases.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction failure is relatively common in young high-risk athletes. The purpose of this study was to examine a single center's 10-year experience with ACL reconstructions in pediatric and adolescent patients to better define short-term failure rates and risk factors for revision ACL surgery. METHODS: This institutional review board-approved retrospective study included all patients who underwent a primary ACL reconstruction between 2002 and 2013. Chart and radiographic review was performed to assess patient demographic, injury, and surgical data including growth plate status, concomitant ligament/meniscus/cartilage injury, surgical procedures, femoral drilling technique, graft source and type, femoral and tibial fixation devices, and graft size. Graft failures had to be confirmed both with clinical examination and magnetic resonance imaging or the patient had to undergo a revision ACL reconstruction. Potential factors associated with failure were evaluated using either parametric or nonparametric analysis as appropriate. RESULTS: A total of 561 ACL reconstructions were performed that met our inclusion criteria. The average patient age was 15.4 years (range, 5 to 19 y) and 53% of the patients were male. In all, 54 failures were identified for a 9.6% failure rate. Soft tissue grafts were twice as likely to fail compared with patellar tendon grafts (13% vs. 6%; P<0.001). Multivariate analysis revealed that graft choice (soft tissue vs. patellar tendon) was the primary variable predictive of failure (P<0.05), with interactions/mediating effects contributed by maturity (growth plate status) and ACL technique (P<0.05). The average time to failure was 13.6 months and hamstring grafts and anatomic femoral tunnels were both found to fail earlier (P<0.05). During the study period, approximately 8% of patients sustained a contralateral ACL injury. CONCLUSIONS: ACL failure rates in adolescent and pediatric patients vary based on patient age, graft selection, and surgical technique. Bone patellar tendon bone autografts had the lowest failure rate in this high-risk population. LEVEL OF EVIDENCE: Level IV-retrospective case series.

Skeletal muscle fiber-type specific succinate dehydrogenase activity in cerebral palsy.

INTRODUCTION: Children with cerebral palsy (CP) exhibit increased energy expenditure during movement, but whether this is due in part to decrements in skeletal muscle mitochondrial oxidative capacity is unknown. Accordingly, we compared fiber-type specific succinate dehydrogenase (SDH) activity in children with CP with typically developing (TD) children. METHODS: SDH activity and myofiber areas of type 1 and 2A fibers were measured in semitendinosus biopsies of both groups (n = 5/group). RESULTS: SDH activity was ∼35% higher in type 1 compared with type 2A fibers, but there were no differences between groups. Average myofiber area was 45% smaller in CP versus TD (P < 0.05), and type 2A fibers were 32% larger than type 1 fibers (P < 0.05) only in TD children. CONCLUSIONS: Fiber-type specific SDH activity is similar between TD children and children with CP. This suggests that increased energy expenditure in children with CP is not related to impaired mitochondrial oxidative capacity. Muscle Nerve, 2016 Muscle Nerve 55: 122-124, 2017.

Update on neuromuscular disorders in pediatric orthopaedics: Duchenne muscular dystrophy, myelomeningocele, and cerebral palsy.

The purpose of this seminar was to review a large range of lower extremity and neuromuscular disorders. Because of the diversity of the topics covered, including clubfoot and vertical talus treatment, management of Legg-Calve-Perthes disease, and limb lengthening in dwarfism, this review will focus on the neuromuscular subsection reviewing the current management of the muscular dystrophies, myelomeningocele, and cerebral palsy.

Adults with cerebral palsy and functional decline: A cross-sectional analysis of patient-reported outcomes from a novel North American registry.

BACKGROUND: Adults with cerebral palsy (CP) have unique healthcare needs and risks, including high risk of functional decline. Understanding functional decline is an area of priority for CP research. OBJECTIVE: Describe factors associated with patient-reported changes in function among adults with CP living in the community. METHODS: Cross-sectional analysis of adult patient-reported outcomes collected by the CP Research Network (CPRN) Community Registry. RESULTS: Participants included 263 respondents (76% female (n = 200); mean age 42 years (SD 14); 95% White (n = 249); 92% non-Hispanic (n = 241)). Many reported functional changes, most commonly a decline in gross motor function since childhood (n = 158, 60%). Prevalence of gross motor decline varied significantly by Gross Motor Function Classification System (GMFCS) level (p < 0.001), but neither hand function decline (p = 0.196) nor communication decline (p = 0.994) differed by GMFCS. All types of decline increased with increasing age, with statistically significant differences between age groups (p < 0.001 gross motor; p = 0.003 hand function; p = 0.004 communication). Those with spastic CP (n = 178) most commonly reported gross motor functional decline (n = 108/178, 60.7%). However, the prevalence of gross motor decline did not significantly differ between those with spastic CP and those without spastic CP (p = 0.789). CONCLUSIONS: Many adults in the CPRN Community Registry reported functional decline, most commonly in gross motor function. Functional decline across domains increased with age. Further research into risk stratification and preventive and rehabilitative measures is needed to address functional decline across the lifespan.

Cerebral palsy research network community registry adult surveys on function & pain: Successes, challenges, and future directions.

NARRATIVE SUMMARY: The formation of a patient-reported outcomes registry to provide information about functional changes and pain among adults with cerebral palsy (CP) was identified as a priority to address the gap in knowledge and practice about aging and CP. The Cerebral Palsy Research Network collaborated with consumers, clinicians, and researchers to create an interactive internet platform, MyCP, to host a Community Registry. MyCP also provides educational programming, access to webinars and community forums, and fitness opportunities. The registry hosts surveys on function and pain for adults with CP, which provide cross-sectional and longitudinal data about these important issues. Surveys include previously validated measures with normative values that have been used with other populations and investigator developed questions. Enrollment in the registry is growing but needs to reflect the population of adults with CP, which limits generalizability. Future initiatives involve strategies to increase consumer engagement and enrollment.

Reduced satellite cell population may lead to contractures in children with cerebral palsy.

AIM: Satellite cells are the stem cells residing in muscle responsible for skeletal muscle growth and repair. Skeletal muscle in cerebral palsy (CP) has impaired longitudinal growth that results in muscle contractures. We hypothesized that the satellite cell population would be reduced in contractured muscle. METHOD: We compared the satellite cell populations in hamstring muscles from participants with CP contracture (n=8; six males, two females; age range 6-15y; Gross Motor Function Classification System [GMFCS] levels II-V; 4 with hemiplegia, 4 with diplegia) and from typically developing participants (n=8; six males, two females, age range 15-18y). Muscle biopsies were extracted from the gracilis and semitendinosus muscles and mononuclear cells were isolated. Cell surface markers were stained with fluorescently conjugated antibodies to label satellite cells (neural cell adhesion molecule) and inflammatory and endothelial cells (CD34 and CD4 respectively). Cells were analyzed using flow cytometry to determine cell populations. RESULTS: After gating for intact cells a mean of 12.8% (SD 2.8%) were determined to be satellite cells in typically developing children, but only 5.3% (SD 2.3%; p<0.05) in children with CP. Hematopoietic and endothelial cell types were equivalent in typically developing children and children with CP (p>0.05) suggesting the isolation procedure was valid. INTERPRETATION: A reduced satellite cell population may account for the decreased longitudinal growth of muscles in CP that develop into fixed contractures or the decreased ability to strengthen muscle in CP. This suggests a unique musculoskeletal disease mechanism and provides a potential therapeutic target for debilitating muscle contractures.