ICF linking of patient-reported therapy goals for children with acquired upper extremity impairment.

BACKGROUND: Patient reported outcome measures are used to evaluate hand therapy outcomes. Yet, limited evidence is available regarding the outcomes children desire from hand therapy. PURPOSE: To determine the desired treatment outcomes of children with acquired upper extremity impairments. STUDY DESIGN: Descriptive case series METHODS: Two raters independently applied International Classification of Function, Disability and Health (ICF) linking rules to the Canadian Occupational Performance goals of 151 children, age 6-18, receiving occupational therapy for acquired upper extremity impairments. Prevalence of the linked ICF codes was examined using frequency distributions. Kappa and the proportion of positive agreement assessed inter-rater agreement of the linked codes. RESULTS: Following consensus, two independent raters linked 894 meaningful concepts to the study population's 501 goals derived from the Canadian Occupational Performance. Ninety-two unique ICF codes were linked to these 894 meaningful concepts. Twenty-three ICF codes account for 77.2% of the most frequently linked codes. For these top 23 codes, the greatest proportion (51.4%) of ICF codes are in the d4 mobility chapter representing specific constructs of hand and arm use. The second largest proportion (14.2%) of linked codes are in the d9 Community, society and civic life chapter aligning with participation in sports, music, performing arts and play. Within the d5 self-care chapter, the study population's top priorities included hair care, fitness and drinking. The primary concerns within the b body functions domain are reduced pain, improved joint mobility and strength. CONCLUSION: The study population's top priorities align with specific dimensions of hand and arm use and participation in sports and fitness, performing arts, and play. Further research may elucidate alignment of these patient-desired outcomes and the item banks of commonly used patient reported outcome measurement scales in this population.

Timing of proteasome inhibition as a pharmacologic strategy for prevention of muscle contractures in neonatal brachial plexus injury.

Neonatal brachial plexus injury (NBPI) causes disabling and incurable contractures, or limb stiffness, which result from proteasome-mediated protein degradation impairing the longitudinal growth of neonatally denervated muscles. We recently showed in a mouse model that the 20S proteasome inhibitor, bortezomib, prevents contractures after NBPI. Given that contractures uniquely follow neonatal denervation, the current study tests the hypothesis that proteasome inhibition during a finite window of neonatal development can prevent long-term contracture development. Following neonatal forelimb denervation in P5 mice, we first outlined the minimum period for proteasome inhibition to prevent contractures 4 weeks post-NBPI by treating mice with saline or bortezomib for varying durations between P8 and P32. We then compared the ability of varying durations of longer-term proteasome inhibition to prevent contractures at 8 and 12 weeks post-NBPI. Our findings revealed that proteasome inhibition can be delayed 3-4 days after denervation but is required throughout skeletal growth to prevent contractures long term. Furthermore, proteasome inhibition becomes less effective in preventing contractures beyond the neonatal period. These therapeutic effects are primarily associated with bortezomib-induced attenuation of 20S proteasome ß1 subunit activity. Our collective results, therefore, demonstrate that temporary neonatal proteasome inhibition is not a viable strategy for preventing contractures long term. Instead, neonatal denervation causes a permanent longitudinal growth deficiency that must be continuously ameliorated during skeletal growth. Additional mechanisms must be explored to minimize the necessary period of proteasome inhibition and reduce the risk of toxicity from long-term treatment.

Rare Presentation of Pediatric Multiple Enchondromatosis Limited to Single Ray or Single Nerve Distribution in the Hand: A Multicenter Case Series.

BACKGROUND: Multiple enchondromas in the pediatric hand is a relatively rare occurrence and the literature regarding its incidence and treatment is sparse. Within this rare subset of patients, we identified a unique cohort in which lesions are confined to multiple bones in a single ray or adjacent rays within a single nerve distribution. We review the clinical and pathologic characteristics and describe the indications for and outcomes of treatment in this unique subset of patients as well as offer conjectures about its occurrence. METHODS: Institutional review board (IRB)-approved retrospective multicenter study between 2010 and 2018 identified subjects with isolated multiple enchondromas and minimum 2-year follow-up. Data analyzed included demographics, lesion quantification and localization, symptoms and/or fracture(s), treatment of lesion(s), complications, recurrence, and presence of malignant transformation. RESULTS: Ten patients were evaluated with average age at presentation of 9 years (range: 4 to 16) and mean clinical follow-up of 6 years (range: 2.8 to 8.6). Five subjects had multiple ray involvement in a single nerve distribution and 5 had single ray involvement with an average of 4 lesions noted per subject (range: 2 to 8). All children in the study had histopathologic-proven enchondromas and underwent operative curettage±bone grafting. Indications for surgical intervention included persistent pain, multiple prior pathologic fractures, impending fracture and deformity. During the study period three subjects experienced pathologic fracture treated successfully with immobilization. Recurrence was noted in 40% at an average of 105 weeks postoperatively (range: 24 to 260) and appears higher than that reported in the literature. No case of malignant transformation was observed during the study period. CONCLUSIONS: A rare subset of pediatric patients with multiple enchondromas of the hand is described with lesions limited to a single ray or single nerve distribution. Further awareness of this unique subset of patients may increase our understanding of the disease and improve patient outcomes. LEVEL OF EVIDENCE: Level IV-therapeutic (case series).

Is a Right Angle the Right Angle? Normal Coronal Radiographic Alignment in the Pediatric Finger Phalanges.

BACKGROUND: Quantifying pediatric phalanx fracture displacement requires understanding the normal radiographic alignment of pediatric phalanges, which has never been assessed in the coronal plane, although prior studies have assumed the articular surfaces and physes to be perpendicular to the diaphyses. This study tests the hypothesis that these relationships are not uniformly perpendicular and instead vary by digit and age. METHODS: Normal hand bone age radiographs were retrospectively reviewed from 40 males and 40 females 2 to 18 years old. For each finger proximal phalanx (P1) and middle phalanx (P2), 2 raters each measured twice the angle between the diaphysis and distal articular surface (D-DA), diaphysis and physis (D-P, when physis present), and diaphysis and proximal articular surface (D-PA). Intra-rater and inter-rater reliability were calculated with intraclass correlation coefficients. 95% confidence intervals were calculated for each angle for each digit, phalanx, age group, and sex to determine which angles ~90 degrees. Variability among ages and sex was assessed with analysis of variance. RESULTS: Intra-rater and inter-rater intraclass correlation coefficients were >0.90, except in P2 ∠D-DA in children under 8 years old with unossified P2 condyles. Overall, only 173 (47.8%) of 362 confidence intervals included 90 degrees. Three angles of the small finger (P1 ∠D-DA, P2 ∠D-P, P2 ∠D-PA) never ~90 degrees at any age or sex, with an average 10 degrees ulnar tilt of the small finger proximal interphalangeal joint. Of the 24 angles across digits and phalanges, 10 varied significantly with age, especially in the index and middle finger P1 where initially wedge-shaped epiphyses progressively became more symmetric with age. CONCLUSIONS: The coronal radiographic angles between the phalangeal diaphyses and articular surfaces or physes differ from 90 degrees more than half the time in pediatric fingers, and nearly half the angles vary by age. These findings demonstrate that the articular surfaces and physes of the pediatric finger phalanges are not uniformly perpendicular to the diaphyses, underscoring the need to consider the variability among digits, phalanges, ages and subjects. LEVEL OF EVIDENCE: Level IV.

Describing pediatric fractures in the era of ICD-10.

Childhood fractures are extremely common. The recent trend is to direct certain fracture care from orthopedic specialists to primary care clinicians. However, to confirm an appropriate level of treatment, the initial diagnosis must be accurate, the description precise, and the communication between those caring for the child consistent. This review illustrates descriptors used at one institution that are based on terminology consensually created between radiologists and orthopedic surgeons for common pediatric fracture types and their displacement, and that satisfy the expanded and detailed International Statistical Classification of Diseases and Related Health Problems (ICD)-10 requirements for successful coding.

A psychometric comparison of patient-reported outcome measures used in pediatric hand therapy.

STUDY DESIGN: Retrospective case series. INTRODUCTION: Patient-reported outcome measures are important for research and also for informing clinical practice. The Pediatric Outcomes Data Collection Instrument (PODCI) and the Canadian Occupational Performance Measure (COPM) are commonly used in pediatric hand therapy. Both are validated in research, but no data exist regarding their relative merits for clinical practice. PURPOSE OF THE STUDY: This study compares the psychometric properties of the PODCI and COPM in children receiving hand therapy to examine their relative utility in clinical practice. METHODS: We assessed the psychometric properties of the PODCI and COPM in 75 children receiving hand therapy. Treatment outcomes were assessed simultaneously with the PODCI (Upper Extremity Function and Pain and Comfort scales), COPM (Performance and Satisfaction scales) at baseline and posttreatment time points. Interim scores were included for a subset of patients. Each scale was assessed for responsiveness, ceiling effect, and concurrent and discriminate validity. RESULTS: All scales, except PODCI/Pain from interim to completion, were able to detect changes over the course of therapy. However, both COPM scales demonstrated greater responsiveness and less severe ceiling effects than both PODCI scales at all time points. All scales had weak concurrent validity and limited discriminate validity. CONCLUSIONS: The COPM is more responsive to changes during treatment and less hindered by a ceiling effect than the PODCI. Weak concurrent validity between the PODCI and COPM suggests that they measure different things in this population.

Outcomes of Spinal Accessory-to-Suprascapular Nerve Transfers for Brachial Plexus Birth Injury.

PURPOSE: The results of a spinal accessory nerve-to-suprascapular (SAN-SSN) nerve transfer for brachial plexus birth injuries (BPBIs) have thus far been presented only in limited case series. Our study evaluates the recovery of shoulder function of patients who underwent an SAN-SSN for BPBI as an isolated procedure or as part of a multinerve reconstruction (MNR) surgery. METHODS: We retrospectively reviewed the medical records of patients at a single institution who underwent an SAN-SSN after BPBI. Inclusion criteria were patients with both preoperative and a minimum 12-months postoperative active movement scale (AMS) scores. Patients for whom the primary surgery involved tendon transfers were excluded. The primary outcome measures were AMS scores for shoulder abduction, forward flexion, and external rotation and secondary outcomes included the need for further shoulder surgery to improve function. RESULTS: Seventy-three patients met the inclusion criteria. Forty-three patients (58.9%) obtained functional shoulder motion (AMS ≥ 6) of at least 1 of 3 planes (abduction/flexion/external rotation) following surgery, with 13 patients (17.8%) achieving full recovery of 1 of these shoulder motions against gravity (AMS = 7). Fifty-six patients (76.7%) did not undergo subsequent tendon transfers or corrective osteotomies to augment shoulder function. The MNR procedures were performed in 46 patients (63%), of whom 45.7% gained a functional recovery. In 27 patients for whom SAN-SSN nerve transfer was conducted in isolation, 81.5% gained functional shoulder motion. However, isolated SAN-SSNs were conducted at a later age than MNR procedures (13.2 vs 4.8 months) and had higher preoperative AMS scores. The anterior and posterior approaches for SAN-SSN were both found to be effective when used for SAN-SSN in BPBI. When the follow-up duration cutoff was set to 3 years, the outcomes were found to be superior. CONCLUSIONS: In 76.7% of the patients, SAN-SSN was able to recover function that was sufficient to prevent tendon transfers and corrective osteotomies. A cutoff of 3 postoperative years should be used as a benchmark for analyzing the results of this procedure. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

A Bundled Payment Model for Pediatric Distal Radius Fractures: Defining an Episode of Care.

BACKGROUND: Distal radius fractures are the most common fracture of childhood, occurring in ∼1 per 100 children annually. Given the high incidence of these fractures, we explored feasibility of a bundled payment model. We determined the total treatment costs for each child and identified components of fracture management that contributed to variations in cost. METHODS: We retrospectively reviewed all hospital and physician costs related to the treatment of closed distal radius fractures at a large academic children's hospital. We included all children age 2 to 15 years treated by an orthopaedic surgeon for an isolated closed distal radius fracture between 2013 and 2015. We compared total treatment costs by fracture management approach. We then estimated the contribution of each component of fracture management to total treatment costs using linear regression. RESULTS: We identified 5640 children meeting the inclusion criteria, of which 4602 (81.6%) received closed treatment without manipulation, 922 (16.3%) underwent closed reduction in the clinic, emergency department, or radiology procedure suite, and 116 (2.1%) underwent treatment in the operating room. The median cost for closed treatment without manipulation was $1390 [interquartile range (IQR) 1029 to 1801], compared with $4263 (IQR, 3740 to 4832) for closed reduction and $9389 (IQR, 8272 to 11,119) for closed reduction and percutaneous pinning (P<0.001). In multivariable regression analysis, fracture management approach and use of the operating room environment were the largest cost drivers (P<0.001, R=0.88). Closed reduction in the clinic or emergency department added $894 (95% confidence interval, 819-969) to treatment costs, while closed reduction in the operating room added $5568 (95% confidence interval, 5224-6297). Location of the initial clinical evaluation, number of radiographic imaging series obtained, and number of orthopaedic clinic visits also contributed to total costs. CONCLUSIONS: Closed pediatric distal radius fractures treated without manipulation show small variations in treatment costs, making them well suited for bundled payment. Bundled payments for these fractures could reduce costs by encouraging adoption of existing evidence-based practices. LEVEL OF EVIDENCE: Level III-therapeutic.

Increasing Brace Treatment for Pediatric Distal Radius Buckle Fractures: Using Quality Improvement Methodology to Implement Evidence-based Medicine.

BACKGROUND: Multiple randomized trials have showed equivalent outcomes and improved patient/family satisfaction using a removable brace to treat pediatric distal radius buckle fractures (DRBF). We tested the hypothesis that we could use quality improvement (QI) methodology to increase the proportion of patients with DRBF treated with removable braces at 2 tertiary care orthopaedic clinics from a baseline of 34.8% to 80%. METHODS: Clinic billing records were reviewed monthly to determine treatment (brace vs. cast) of DRBF and tracked using control charts (p-chart). Balance measures including correct application of the diagnostic criteria and algorithm were monitored. Process measures including the number of follow-up visits, radiographs obtained, and total cost of treatment were collected. Baseline data were obtained over a 3-month period, followed by a 12-month period of interventions using Plan-Do-Study-Act cycles targeting both individuals and groups of providers. RESULTS: The proportion of DRBF treated in a brace increased from a combined baseline of 34.8% to a combined 84% at the end of the study period. Following intervention, 83% (15/18) of providers began using braces for a majority of patients (defined as >67%), with only 1 provider continuing to use casts 100% of the time. Patient preference was cited as the most common reason for use of cast treatment. There was a significant decrease in the number of radiographs obtained at 1 of 2 institutions. The charges for brace treatment averaged $630 less per patient than for cast treatment, leading to an estimated medical-cost savings of $205,000 following intervention. CONCLUSIONS: Implementation of brace treatment for pediatric DRBF using QI methodology resulted in a shift toward brace treatment in the majority of patients, leading to substantial medical and nonmedical cost savings. Although patient preference was cited as the most common reason for persistent cast treatment, the data show the use of cast treatment to be more dependent upon individual provider preference. LEVEL OF EVIDENCE: Level II-therapeutic.

Extensor Tendon Injury Associated With Dorsal Entry Flexible Nailing of Radial Shaft Fractures in Children: A Report of 5 New Cases and Review of the Literature.

BACKGROUND: Extensor pollicis longus (EPL) tendon injury following the dorsal approach to elastic stable intramedullary nailing (ESIN) of the radius has been reported in a growing number of cases in the literature. This study includes 5 new cases from our institution as well as a comprehensive review of previously reported cases from the literature. METHODS: We conducted a retrospective chart review of all patients undergoing ESIN between January 1, 2004 and December 31, 2013 at our institution. Those patients with an EPL injury or rupture were identified and clinical data collected included operative technique, diagnosis, treatment, and outcomes data. In addition, we performed a systematic review of the literature using Pubmed MEDLINE database, the Chochrane database, Scopus, Web of Science, and Embase. A total of 28 cases of EPL injury following ESIN of the radius were identified in the literature and the relevant data were extracted from those studies. RESULTS: All 33 pediatric cases of EPL tendon injury occurred after entry to the radial canal was obtained by the dorsal approach to ESIN. EPL injury was diagnosed an average of 10 weeks following the index procedure. Extensor indicis pollicis to EPL transfer was performed in 13 patients, tendon release/lysis of adhesions in 5, EPL repair in 2, EPL graft reconstruction from palmaris longus tendon in 1, 3 patients refused further intervention, and treatment was unreported in 7 cases. By 12-month follow-up, all operatively treated patients had a good functional outcome with near anatomic extension at the thumb interphalangeal joint, no pain, and no further complication. CONCLUSIONS: EPL tendon injury was found to be a complication unique to the dorsal entry approach for ESIN of the radius. The lateral approach appears to offer a safer alternative with regard to the EPL tendon. We suggest that physicians consider the risk of EPL tendon injury when planning for ESIN of the radius, and make an effort to avoid direct injury when using a dorsal approach. LEVEL OF EVIDENCE: Level III-therapeutic.

Pediatric Metacarpal Fractures.

Metacarpal fractures account for 10% to 35% of all pediatric hand fractures. Pediatric metacarpal fractures commonly occur in patients aged 13 to 16 years, with most injuries sustained during sports activities. Pseudoepiphyses can be confused with metacarpal fractures; however, a careful physical examination can help physicians distinguish the two. Thumb metacarpal base fractures that involve the physis warrant special attention. Thumb metacarpal base fractures with lateral metaphyseal fragments and pediatric Bennett fracture variants (Salter-Harris type III and type IV fractures) are unstable and require surgical management. Finger metacarpal base fractures, especially those in young children, are often the result of high-energ y injuries and should increase a physician's concern for compartment syndrome. Metacarpal shaft fractures can result from a simple bending moment; however, they also can result from a rotational force, which may cause finger crossover that will not remodel and requires reduction. Metacarpal neck fractures account for three-fourths of all finger metacarpal fractures, and increasing acceptable alignment of the index finger through the little finger metacarpal necks (10°, 20°, 30°, and 40° across the digits, respectively) is commonly recommended. Metacarpal head fractures are rare intra-articular injuries that require anatomic fixation and may be underappreciated in children because of the complex geometry and largely cartilaginous nature of the metacarpal head.

Pediatric Phalanx Fractures.

Phalangeal fractures are the most common type of hand fracture that occurs in the pediatric population and account for the second highest number of emergency department visits in the United States for fractures. The incidence of phalangeal fractures is the highest in children aged 10 to 14 years, which coincides with the time that most children begin playing contact sports. Younger children are more likely to sustain a phalangeal fracture in the home setting as a result of crush and laceration injuries. Salter-Harris type II fractures of the proximal phalanx are the most common type of finger fracture. An unmineralized physis is biomechanically weaker compared with the surrounding ligamentous structures and mature bone, which make fractures about the physis likely. A thorough physical examination is necessary to assess the digital cascade for signs of rotational deformity and/or coronal malalignment. Plain radiographs of the hand and digits are sufficient to confirm a diagnosis of a phalangeal fracture. The management of phalangeal fractures is based on the initial severity of the injury and depends on the success of closed reduction techniques. Nondisplaced phalanx fractures are managed with splint immobilization. Stable, reduced phalanx fractures are immobilized but require close monitoring to ensure maintenance of fracture reduction. Unstable, displaced phalanx fractures require surgical management, preferably via closed reduction and percutaneous pinning.

Pediatric Distal Radius Fractures.

Distal radius fractures are the most common orthopaedic injury that occur in the pediatric population. The annual incidence of distal radius fractures has increased as a result of earlier participation in sporting activities, increased body mass index, and decreased bone mineral density. Most distal radius fractures are sustained after a fall onto an outstretched arm that results in axial compression on the extremity or from direct trauma to the extremity. Physeal fractures of the distal radius are described based on the Salter-Harris classification system. Extraphyseal fractures of the distal radius are described as incomplete or complete based on the amount of cortical involvement. A thorough physical examination of the upper extremity is necessary to rule out any associated injuries. PA and lateral radiographs of the wrist usually are sufficient to diagnose a distal radius fracture. The management of distal radius fractures is based on several factors, including patient age, fracture pattern, and the amount of growth remaining. Nonsurgical management is the most common treatment option for patients who have distal radius fractures because marked potential for remodeling exists. If substantial angulation or displacement is present, closed reduction maneuvers with or without percutaneous pinning should be performed. Patients with physeal fractures of the distal radius that may result in malunion who present more than 10 days postinjury should not undergo manipulation of any kind because of the increased risk for physeal arrest.

Pediatric Scaphoid Fractures.

Scaphoid fractures are the most common type of carpal injuries that occur in children and adolescents. The injury pattern seen in children and adolescents who have scaphoid fractures has recently shifted to resemble that of adults who have scaphoid fractures, with scaphoid waist fractures being the most common injury pattern. This shift has been attributed to increased body mass index in children and adolescents as well as more intense participation in extreme sports by both children and adolescents. The diagnosis of scaphoid fractures is based on both a clinical examination and radiographic fi ndings. If a scaphoid fracture is clinically suspected but initial radiographs are negative, cast immobilization followed by repeat imaging can lead to accurate diagnosis of the injury. MRI can aid in the diagnosis of a scaphoid injury in pediatric patients with incomplete ossifi cation of the scaphoid. Acute nondisplaced scaphoid fractures have a high rate of healing with cast immobilization; however, surgery should be considered in patients who have displaced scaphoid fractures with delayed presentation. In general, patients with scaphoid fractures who undergo appropriate treatment and achieve successful union have excellent long-term functional outcomes.

The Effect of Scapular Position on Magnetic Resonance Imaging Measurements of Glenohumeral Dysplasia Caused by Neonatal Brachial Plexus Palsy.

PURPOSE: Neonatal brachial plexus palsy (NBPP) frequently causes glenohumeral dysplasia. Quantification of this dysplasia on magnetic resonance imaging can determine the need for and the success of nonsurgical or surgical intervention. However, we hypothesize that the variable position of the scapula on the thorax between affected and unaffected shoulders affects dysplasia measurements. METHODS: Magnetic resonance imaging studies were analyzed from 19 NBPP patients (ages 0.8-18 years; median, 2.4 years) without prior shoulder surgery. Three reviewers measured the glenoid version angle (GVA) and percentage of humeral head anterior to the midscapular line (PHHA) on standard axial images ("thoracic axial") and on reformatted axial images aligned perpendicular to the scapular plane ("scapular axial"), which corrects for scapulothoracic position. Scapular tilt and protraction were measured to assess their impact on the difference between thoracic and scapular GVA and PHHA measurements. Intra- and interrater reliability were calculated for GVA and PHHA on both views. RESULTS: The GVA of the affected shoulder was significantly greater on thoracic than on scapular images, by an average of 5° and as much as 34°. The PHHA was significantly less in the affected shoulders on thoracic than on scapular images, by an average of 5% and as much as 33% of humeral head width. The difference in GVA, but not PHHA, between thoracic and scapular axial images in the affected shoulder correlated with scapular tilt. Unaffected shoulders showed no significant difference in GVA or PHHA between thoracic and scapular axial images. Interrater reliability ranged from fair to substantial and did not differ between thoracic and scapular images. CONCLUSIONS: Thoracic axial images overestimate the severity of glenohumeral dysplasia in NBPP, owing at least in part to the variable position of the scapula on the thorax. This confounding effect must be considered in interpretation of axial quantitative measures of glenohumeral dysplasia in NBPP. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic III.

Does using PAs in the closed treatment of pediatric forearm fractures increase malunion risk?

PURPOSE: This study assessed whether using physician assistants (PAs) for fracture follow-up during nonoperative management of pediatric forearm fractures was associated with an increased risk of malunion. METHODS: The study was a retrospective review of charts of 141 children under age 18 years who were treated nonoperatively in the division of orthopedics over 12 months for forearm fractures. The effect of type and number of follow-up providers on risk of malunion was determined and controlled for fracture type, location, and initial angulation. Logistic regression, Fisher exact test, and Cochran-Armitage trend test were used to analyze the data, with P < .05 indicating statistical significance. RESULTS: Using strict criteria, malunion was identified in 42 (30%) of 141 patients. Follow-up provided by even up to four PAs did not increase malunion risk. Transfer of care between two attending physicians increased malunion risk, independent of fracture characteristics. CONCLUSION: The involvement of even multiple PAs during follow-up management of nonoperatively treated pediatric forearm fractures is not associated with an increase in the risk of malunion. These findings are consistent with previous published works that highlighted the safe and valuable role PAs can play in the management of common fractures.

Eccentric Capitellar Ossification Limits the Utility of the Radiocapitellar Line in Young Children.

BACKGROUND: The radiocapitellar line (RCL) has long been used for the radiographic evaluation of elbow alignment. In children, the capitellar ossific nucleus serves as a proxy for the entire capitellum, but this substitution has not been verified. Using magnetic resonance imaging (MRI), we sought to understand how maturation of the ossific nucleus of the capitellum affects the utility of RCL throughout skeletal maturation of the elbow. METHODS: The RCL was drawn on coronal and sagittal MRIs in 82 children (43 boys, 39 girls; age range, 1 to 13 y) with at least 3 patients in each 1-year interval age group. The perpendicular distance of the RCL from the center of both the cartilaginous capitellum and the capitellar ossific nucleus was measured relative to its total width, and a percent offset for each measurement was calculated. Logarithmic regression analysis was performed to analyze the effect of age and sex on percent offset. RESULTS: The RCL reliably intersected with the central third of the cartilaginous capitellum at all ages in both planes. Although the RCL intersected with the ossified capitellum in all but 3 measurements, it intersected with the central third of the ossified capitellum less often in younger children in both sagittal (B=0.47, P<0.001) and coronal (B=0.31, P=0.002) planes. Percent offset decreased significantly with age in a logarithmic manner in both sagittal (r=0.57, P<0.001) and coronal (r=-0.47, P<0.001) planes. 95% confidence intervals predict that the sagittal plane RCL will accurately intersect the central third of the ossified capitellum by age 10 years in girls and age 11 years in boys but not in the coronal plane. CONCLUSIONS: Eccentric ossification of the capitellum explains RCL variability in young children. The RCL does not reliably intersect the central third of the ossified capitellum until ages 10 years in girls and 11 years in boys in the sagittal plane. The RCL should be used within its limitations in skeletally immature children and should be combined with advanced imaging if necessary.

Afferent Innervation, Muscle Spindles, and Contractures Following Neonatal Brachial Plexus Injury in a Mouse Model.

PURPOSE: We used an established mouse model of elbow flexion contracture after neonatal brachial plexus injury (NBPI) to test the hypothesis that preservation of afferent innervation protects against contractures and is associated with preservation of muscle spindles and ErbB signaling. METHODS: A model of preganglionic C5 through C7 NBPI was first tested in mice with fluorescent axons using confocal imaging to confirm preserved afferent innervation of spindles despite motor end plate denervation. Preganglionic and postganglionic injuries were then created in wild-type mice. Four weeks later, we assessed total and afferent denervation of the elbow flexors by musculocutaneous nerve immunohistochemistry. Biceps muscle volume and cross-sectional area were measured by micro computed tomography. An observer who was blinded to the study protocol measured elbow flexion contractures. Biceps spindle and muscle fiber morphology and ErbB signaling pathway activity were assessed histologically and immunohistochemically. RESULTS: Preganglionic and postganglionic injuries caused similar total denervation and biceps muscle atrophy. However, after preganglionic injuries, afferent innervation was partially preserved and elbow flexion contractures were significantly less severe. Spindles degenerated after postganglionic injury but were preserved after preganglionic injury. ErbB signaling was inactivated in denervated spindles after postganglionic injury but ErbB signaling activity was preserved in spindles after preganglionic injury with retained afferent innervation. Preganglionic and postganglionic injuries were associated with upregulation of ErbB signaling in extrafusal muscle fibers. CONCLUSIONS: Contractures after NBPI are associated with muscle spindle degeneration and loss of spindle ErbB signaling activity. Preservation of afferent innervation maintained spindle development and ErbB signaling activity, and protected against contractures. CLINICAL RELEVANCE: Pharmacologic modulation of ErbB signaling, which is being investigated as a therapy for congestive heart failure, may be able to recapitulate the protective effects of afferent innervation in spindle development and contracture prevention. Muscle spindle preservation may also have implications in proprioception and motor learning, both of which are impaired in NBPI.

Contributions of muscle imbalance and impaired growth to postural and osseous shoulder deformity following brachial plexus birth palsy: a computational simulation analysis.

PURPOSE: Two potential mechanisms leading to postural and osseous shoulder deformity after brachial plexus birth palsy are muscle imbalance between functioning internal rotators and paralyzed external rotators and impaired longitudinal growth of paralyzed muscles. Our goal was to evaluate the combined and isolated effects of these 2 mechanisms on transverse plane shoulder forces using a computational model of C5-6 brachial plexus injury. METHODS: We modeled a C5-6 injury using a computational musculoskeletal upper limb model. Muscles expected to be denervated by C5-6 injury were classified as affected, with the remaining shoulder muscles classified as unaffected. To model muscle imbalance, affected muscles were given no resting tone whereas unaffected muscles were given resting tone at 30% of maximal activation. To model impaired growth, affected muscles were reduced in length by 30% compared with normal whereas unaffected muscles remained normal in length. Four scenarios were simulated: normal, muscle imbalance only, impaired growth only, and both muscle imbalance and impaired growth. Passive shoulder rotation range of motion and glenohumeral joint reaction forces were evaluated to assess postural and osseous deformity. RESULTS: All impaired scenarios exhibited restricted range of motion and increased and posteriorly directed compressive glenohumeral joint forces. Individually, impaired muscle growth caused worse restriction in range of motion and higher and more posteriorly directed glenohumeral forces than did muscle imbalance. Combined muscle imbalance and impaired growth caused the most restricted joint range of motion and the highest joint reaction force of all scenarios. CONCLUSIONS: Both muscle imbalance and impaired longitudinal growth contributed to range of motion and force changes consistent with clinically observed deformity, although the most substantial effects resulted from impaired muscle growth. CLINICAL RELEVANCE: Simulations suggest that treatment strategies emphasizing treatment of impaired longitudinal growth are warranted for reducing deformity after brachial plexus birth palsy.

Contribution of denervated muscle to contractures after neonatal brachial plexus injury: not just muscle fibrosis.

INTRODUCTION: We investigated the contribution of muscle fibrosis to elbow flexion contractures in a murine model of neonatal brachial plexus injury (NBPI). METHODS: Four weeks after NBPI, biceps and brachialis fibrosis were assessed histologically and compared with the timing of contracture development and the relative contribution of each muscle to contractures. Modulus of elasticity and hydroxyproline (collagen) content were measured and correlated with contracture severity. The effect of halofuginone antifibrotic therapy on fibrosis and contractures was investigated. RESULTS: Elbow contractures preceded muscle fibrosis development. The brachialis was less fibrotic than the biceps, yet contributed more to contractures. Modulus and hydroxyproline content increased in both elbow flexors, but neither correlated with contracture severity. Halofuginone reduced biceps fibrosis but did not reduce contracture severity. CONCLUSIONS: Contractures after NBPI cannot be explained solely by muscle fibrosis, arguing for investigation of alternate pathophysiologic targets for contracture prevention and treatment.