Sexual Dimorphisms in Skeletal Muscle: Current Concepts and Research Horizons

The complex compositional and functional nature of skeletal muscle makes this organ an essential topic of study for biomedical researchers and clinicians. An additional layer of complexity is added with the consideration of sex as a biological variable. Recent research advances have revealed sexual dimorphisms in developmental biology, muscle homeostasis, adaptive responses, and disorders relating to skeletal muscle. Many of the observed sex differences have hormonal and molecular mechanistic underpinnings, while others have yet to be elucidated. Future research is needed to investigate the mechanisms dictating sex-based differences in the various aspects of skeletal muscle. As such, it is necessary that skeletal muscle biologists ensure that both female and male subjects are represented in biomedical and clinical studies to facilitate the successful testing and development of therapeutics for all patients.

Impact of brachial plexus birth injury on health-related quality of life in adulthood: a mixed methods survey study

PURPOSE

To describe the scope and nature of health concerns, functional impairments, and quality of life issues among adults with brachial plexus birth injury (BPBI).

METHODS

A mixed methods study was conducted by surveying two social media networks of adults with BPBI using a combination of closed-ended and open-ended questions regarding the role of BPBI on ones' health, function, and quality of life. Closed-ended responses were compared across ages and genders. Open-ended responses were qualitatively analyzed to expand upon the close-ended responses.

RESULTS

Surveys were completed by 183 respondents (83% female, age range 20-87 years). BPBI was reported to impact hand and arm use in 80% of participants (including affected and unaffected limbs and bimanual tasks), overall health in 60% (predominantly pain), activity participation in 79% (predominantly activities of daily living and leisure), life roles in 76% (predominantly occupation and parenting), and overall quality of life in 73% (predominantly self-esteem, relationships, and appearance). Significantly more females than males reported other medical conditions and an impact on hand and arm use and life roles. No other responses varied by age or gender.

CONCLUSIONS

BPBI affects many facets of health related quality of life in adulthood with variability among affected individuals.

The Relative Efficacy of Available Proteasome Inhibitors in Preventing Muscle Contractures Following Neonatal Brachial Plexus Injury

BACKGROUND

Contractures following neonatal brachial plexus injury (NBPI) are associated with growth deficits in denervated muscles. This impairment is mediated by an increase in muscle protein degradation, as contractures can be prevented in an NBPI mouse model with bortezomib (BTZ), a proteasome inhibitor (PI). However, BTZ treatment causes substantial toxicity (0% to 80% mortality). The current study tested the hypothesis that newer-generation PIs can prevent contractures with less severe toxicity than BTZ.

METHODS

Unilateral brachial plexus injuries were surgically created in postnatal (5-day-old) mice. Following NBPI, mice were treated with either saline solution or various doses of 1 of 3 different PIs: ixazomib (IXZ), carfilzomib (CFZ), or marizomib (MRZ). Four weeks post-NBPI, mice were assessed for bilateral passive range of motion at the shoulder and elbow joints, with blinding to the treatment group, through an established digital photography technique to determine contracture severity. Drug toxicity was assessed with survival curves.

RESULTS

All PIs prevented contractures at both the elbow and shoulder (p < 0.05 versus saline solution controls), with the exception of IXZ, which did not prevent shoulder contractures. However, their efficacies and toxicity profiles differed. At lower doses, CFZ was limited by toxicity (30% to 40% mortality), whereas MRZ was limited by efficacy. At higher doses, CFZ was limited by loss of efficacy, MRZ was limited by toxicity (50% to 60% mortality), and IXZ was limited by toxicity (80% to 100% mortality) and loss of efficacy. Comparisons of the data on these drugs as well as data on BTZ generated in prior studies revealed BTZ to be optimal for preventing contractures, although it, too, was limited by toxicity.

CONCLUSIONS

All of the tested second-generation PIs were able to reduce NBPI-induced contractures, offering further proof of concept for a regulatory role of the proteasome in contracture formation. However, the narrow dose ranges of efficacy for all PIs highlight the necessity of precise proteasome regulation for preventing contractures. Finally, the substantial toxicity stemming from proteasome inhibition underscores the importance of identifying muscle-targeted strategies to suppress protein degradation and prevent contractures safely.

CLINICAL RELEVANCE

Although PIs offer unique opportunities to establish critical mechanistic insights into contracture pathophysiology, their clinical use is contraindicated in patients with NPBI at this time.

The role of sympathetic innervation in neonatal muscle growth and neuromuscular contractures

Neonatal brachial plexus injury (NBPI), a leading cause of pediatric upper limb paralysis, results in disabling and incurable muscle contractures that are driven by impaired longitudinal growth of denervated muscles. A rare form of NBPI, which maintains both afferent and sympathetic muscle innervation despite motor denervation, protects against contractures. We have previously ruled out a role for NRG/ErbB signaling, the predominant pathway governing antegrade afferent neuromuscular transmission, in modulating the formation of contractures. Our current study therefore investigated the contributions of sympathetic innervation of skeletal muscle in modulating NBPI-induced contractures. Through chemical sympathectomy and pharmacologic modification with a β2 -adrenergic agonist, we discovered that sympathetic innervation alone is neither required nor sufficient to modulate contracture formation in neonatal mice. Despite this, sympathetic innervation plays an intriguing sex-specific role in mediating neonatal muscle growth, as the cross-sectional area (CSA) and volume of normally innervated male muscles were diminished by ablation of sympathetic neurons and increased by β-adrenergic stimulation. Intriguingly, the robust alterations in CSA occurred with minimal changes to normal longitudinal muscle growth as determined by sarcomere length. Instead, β-adrenergic stimulation exacerbated sarcomere overstretch in denervated male muscles, indicating potentially discrete regulation of muscle width and length. Future investigations into the mechanistic underpinnings of these distinct aspects of muscle growth are thus essential for improving clinical outcomes in patients affected by muscle disorders in which both length and width are affected.

Pediatric Flexor Tendon Injuries

The diagnosis and management of pediatric flexor tendon injuries present unique challenges to the hand surgeon. Examination of young children is not always straightforward, and tendon lacerations are frequently diagnosed late--sometimes weeks or months after the inciting injury. Four- and six-strand repair techniques are supported by recent literature, though the surgeon must remain diligent to ensure gliding of a bulky repair in a narrow tendon sheath. Beyond the operating room, postoperative management must be tailored to accommodate nuances specific to patient age and behavioral development. A fluid, patient-specific approach to every stage of management is critical for the successful treatment of pediatric flexor tendon injuries.

Hand surgery and hand therapy clinical practice guideline for epidermolysis bullosa

What is already known about this topic?

Epidermolysis bullosa (EB) causes blistering and scarring of the hands resulting in contractures fused web spaces and altered function. Surgery is needed to release contractures and web spaces and hand therapy is essential to maintain results, approaches for both differ.

What does this study add?

These guidelines aim to provide information on the surgical and conservative therapeutic hand management of children and adults diagnosed with EB. They are based on available evidence and expert consensus to assist hand surgeons and therapists in decision making, planning and treatment. They highlight the importance of a holistic multidisciplinary team (MDT) approach, where patient priorities are paramount.

Brachial plexus birth injury and cerebral palsy lead to a common contracture phenotype characterized by reduced functional muscle length and strength

Introduction

Brachial plexus birth injury (BPBI) and cerebral palsy (CP) both cause disabling contractures for which no curative treatments exist, largely because contracture pathophysiology is incompletely understood. The distinct neurologic nature of BPBI and CP suggest different potential contracture etiologies, although imbalanced muscle strength and insufficient muscle length have been variably implicated. The current study directly compares the muscle phenotype of elbow flexion contractures in human subjects with BPBI and CP to test the hypothesis that both conditions cause contractures characterized by a deficit in muscle length rather than an excess in muscle strength.

Methods

Subjects over 6 years of age with unilateral BPBI or hemiplegic CP, and with elbow flexion contractures greater than 10 degrees on the affected side, underwent bilateral elbow flexion isokinetic strength testing to identify peak torque and impulse, or area under the torque-angle curve. Subjects then underwent needle microendoscopic sarcomere length measurement of bilateral biceps brachii muscles at symmetric joint angles.

Results

In five subjects with unilateral BPBI and five with hemiplegic CP, peak torque and impulse were significantly lower on the affected versus unaffected sides, with no differences between BPBI and CP subjects in the percent reduction of either strength measurement. In both BPBI and CP, the percent reduction of impulse was significantly greater than that of peak torque, consistent with functionally shorter muscles. Similarly, in both conditions, affected muscles had significantly longer sarcomeres than unaffected muscles at symmetric joint angles, indicating fewer sarcomeres in series, with no differences between BPBI and CP subjects in relative sarcomere overstretch.

Discussion

The current study reveals a common phenotype of muscle contracture in BPBI and CP, with contractures in both conditions characterized by a similar deficit in muscle length rather than an excess in muscle strength. These findings support contracture treatments that lengthen rather than weaken affected muscles. Moreover, the discovery of a common contracture phenotype between CP and BPBI challenges the presumed dichotomy between upper and lower motor neuron lesions in contracture pathogenesis, instead revealing the broader concept of “myobrevopathy”, or disorder of short muscle, warranting increased investigation into the poorly understood mechanisms regulating muscle length.

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).

Sex-specific role of myostatin signaling in neonatal muscle growth, denervation atrophy, and neuromuscular contractures

Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures that result from impaired longitudinal growth of denervated muscles. This deficit in muscle growth is driven by increased proteasome-mediated protein degradation, suggesting a dysregulation of muscle proteostasis. The myostatin (MSTN) pathway, a prominent muscle-specific regulator of proteostasis, is a putative signaling mechanism by which neonatal denervation could impair longitudinal muscle growth, and thus a potential target to prevent NBPI-induced contractures. Through a mouse model of NBPI, our present study revealed that pharmacologic inhibition of MSTN signaling induces hypertrophy, restores longitudinal growth, and prevents contractures in denervated muscles of female but not male mice, despite inducing hypertrophy of normally innervated muscles in both sexes. Additionally, the MSTN-dependent impairment of longitudinal muscle growth after NBPI in female mice is associated with perturbation of 20S proteasome activity, but not through alterations in canonical MSTN signaling pathways. These findings reveal a sex dimorphism in the regulation of neonatal longitudinal muscle growth and contractures, thereby providing insights into contracture pathophysiology, identifying a potential muscle-specific therapeutic target for contracture prevention, and underscoring the importance of sex as a biological variable in the pathophysiology of neuromuscular disorders.

Evaluation of a Grip-Strengthening Algorithm for the Initial Treatment of Chronic, Nonspecific Wrist Pain in Adolescents

Purpose

Chronic, nonspecific wrist pain in adolescents can be challenging to assess and treat. We hypothesized that an algorithmic approach beginning with grip strengthening can alleviate pain, improve function, and identify patients in need of further intervention.

Methods

We retrospectively reviewed the results of a grip-strengthening protocol for adolescents with chronic, nonspecific wrist pain. Before and after treatment, grip strength was measured using handheld dynamometry, and patient-reported pain and function were measured using the adolescent self-reported Pediatric Outcomes Data Collection Instrument’s (PODCI’s) Pain/Comfort and Upper Extremity Function domains (PODCI/pain and PODCI/UE, respectively).

Results

Thirty-two patients (28 female, 4 male) were included, with a mean age of 14 years (range, 10–18 years) and the dominant hand affected in 19, nondominant hand in 9, and bilateral impacts in 4. The mean symptom duration prior to presentation was 9 months (range, 1–63 months); 17 patients had undergone prior immobilization and 5 prior occupational/physical therapy. Grip-strengthening treatment, lasting a mean of 40 days (range, 21–82 days) with a median of 4 therapy visits (range, 2–6), was associated with significantly improved grip strength (mean, 32–48 lbs), PODCI/pain scores (mean, 49.0–78.2 points), and PODCI/UE scores (mean, 78.2–91.2 points). Improvements in grip strength correlated with improvements in PODCI/pain and PODCI/UE scores (r = 0.64 and 0.70, respectively). Eight patients (25%) had either no or incomplete pain relief: 5 underwent successful further intervention (2 ganglion cyst excisions, 1 triangular fibrocartilage complex repair, 1 arthroscopic debridement, 1 steroid injection), 2 received ongoing pain management for generalized pain syndromes, and 1 was lost to further follow-up. No pretreatment variables were identified that predicted failure.

Conclusions

Grip strengthening relieves pain and improves function in the majority of adolescents with chronic, nonspecific wrist pain. Systematic use of this protocol helps to identify patients who require further intervention.

Type of study/level of evidence

Therapeutic IV.

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.

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.

NRG/ErbB signaling regulates neonatal muscle growth but not neuromuscular contractures in neonatal brachial plexus injury

Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures that are driven by impaired growth of denervated muscles. A rare form of NBPI, which maintains afferent muscle innervation despite motor denervation, does not cause contractures. As afferent innervation regulates various aspects of skeletal muscle homeostasis through NRG/ErbB signaling, our current study investigated the role of this pathway in modulating contracture development. Through pharmacologic modification with an ErbB antagonist and NRG1 isoforms, we discovered that NRG/ErbB signaling does not modulate the development of contractures in neonatal mice. Instead, ErbB inhibition impeded growth in nondenervated skeletal muscles, whereas increased ErbB activation exacerbated denervation‐induced skeletal muscle atrophy. This potential regulatory effect of NRG/ErbB signaling on neonatal muscle growth warrants deeper investigation.

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 β1 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.

Clinical practice guidelines: Oral health care for children and adults living with epidermolysis bullosa

BACKGROUND

Inherited epidermolysis bullosa (EB) is a genetic disorder characterized by skin fragility and unique oral features.

AIMS

To provide (a) a complete review of the oral manifestations in those living with each type of inherited EB, (b) the current best practices for managing oral health care of people living with EB, (c) the current best practices on dental implant-based oral rehabilitation for patients with recessive dystrophic EB (RDEB), and (d) the current best practice for managing local anesthesia, principles of sedation, and general anesthesia for children and adults with EB undergoing dental treatment.

METHODS

Systematic literature search, panel discussion including clinical experts and patient representatives from different centers around the world, external review, and guideline piloting.

RESULTS

This article has been divided into five chapters: (i) general information on EB for the oral health care professional, (ii) systematic literature review on the oral manifestations of EB, (iii) oral health care and dental treatment for children and adults living with EB-clinical practice guidelines, (iv) dental implants in patients with RDEB-clinical practice guidelines, and (v) sedation and anesthesia for adults and children with EB undergoing dental treatment-clinical practice guidelines. Each chapter provides recommendations on the management of the different clinical procedures within dental practice, highlighting the importance of patient-clinician partnership, impact on quality of life, and the importance of follow-up appointments. Guidance on the use on nonadhesive wound care products and emollients to reduce friction during patient care is provided.

CONCLUSIONS

Oral soft and hard tissue manifestations of inherited EB have unique patterns of involvement associated with each subtype of the condition. Understanding each subtype individually will help the professionals plan long-term treatment approaches.

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.

Reconstruction of the Suprascapular Nerve in Brachial Plexus Birth Injury: A Comparison of Nerve Grafting and Nerve Transfers

BACKGROUND

Shoulder external rotation recovery in brachial plexus birth injury is often limited. Nerve grafting to the suprascapular nerve and transfer of the spinal accessory nerve to the suprascapular nerve are commonly performed to restore shoulder external rotation, but the optimal surgical technique has not been clearly demonstrated. We investigated whether there was a difference between nerve grafting and nerve transfer in terms of shoulder external rotation recovery or secondary shoulder procedures.

METHODS

This is a multicenter, retrospective cohort study of 145 infants with brachial plexus birth injury who underwent reconstruction with nerve grafting to the suprascapular nerve (n = 59) or spinal accessory nerve to suprascapular nerve transfer (n = 86) with a minimum follow-up of 18 months (median, 25.7 months [interquartile range, 22.0, 31.2 months]). The primary outcome was the Active Movement Scale (AMS) score for shoulder external rotation at 18 to 36 months. The secondary outcome was secondary shoulder surgery. Two-sample Wilcoxon and t tests were used to analyze continuous variables, and the Fisher exact test was used to analyze categorical variables. The Kaplan-Meier method was used to estimate the cumulative risk of subsequent shoulder procedures, and the proportional hazards model was used to estimate hazard ratios (HRs).

RESULTS

The grafting and transfer groups were similar in Narakas type, preoperative AMS scores, and shoulder subluxation. The mean postoperative shoulder external rotation AMS scores were 2.70 in the grafting group and 3.21 in the transfer group, with no difference in shoulder external rotation recovery between the groups (difference, 0.51 [95% confidence interval (CI), -0.31 to 1.33]). A greater proportion of the transfer group (24%) achieved an AMS score of >5 for shoulder external rotation compared with the grafting group (5%) (odds ratio, 5.9 [95% CI, 1.3 to 27.4]). Forty percent of the transfer group underwent a secondary shoulder surgical procedure compared with 53% of the grafting group; this was a significantly lower subsequent surgery rate (HR, 0.58 [95% CI, 0.35 to 0.95]).

CONCLUSIONS

Shoulder external rotation recovery in brachial plexus birth injury remains disappointing regardless of surgical technique, with a mean postoperative AMS score of 3, 17% of infants achieving an AMS score of >5, and a high frequency of secondary shoulder procedures in this study. Spinal accessory nerve to suprascapular nerve transfers were associated with a higher proportion of infants achieving functional shoulder external rotation (AMS score of >5) and fewer secondary shoulder procedures.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Reconstruction of the Suprascapular Nerve in Brachial Plexus Birth Injury: A Comparison of Nerve Grafting and Nerve Transfers

BACKGROUND

Shoulder external rotation recovery in brachial plexus birth injury is often limited. Nerve grafting to the suprascapular nerve and transfer of the spinal accessory nerve to the suprascapular nerve are commonly performed to restore shoulder external rotation, but the optimal surgical technique has not been clearly demonstrated. We investigated whether there was a difference between nerve grafting and nerve transfer in terms of shoulder external rotation recovery or secondary shoulder procedures.

METHODS

This is a multicenter, retrospective cohort study of 145 infants with brachial plexus birth injury who underwent reconstruction with nerve grafting to the suprascapular nerve (n = 59) or spinal accessory nerve to suprascapular nerve transfer (n = 86) with a minimum follow-up of 18 months (median, 25.7 months [interquartile range, 22.0, 31.2 months]). The primary outcome was the Active Movement Scale (AMS) score for shoulder external rotation at 18 to 36 months. The secondary outcome was secondary shoulder surgery. Two-sample Wilcoxon and t tests were used to analyze continuous variables, and the Fisher exact test was used to analyze categorical variables. The Kaplan-Meier method was used to estimate the cumulative risk of subsequent shoulder procedures, and the proportional hazards model was used to estimate hazard ratios (HRs).

RESULTS

The grafting and transfer groups were similar in Narakas type, preoperative AMS scores, and shoulder subluxation. The mean postoperative shoulder external rotation AMS scores were 2.70 in the grafting group and 3.21 in the transfer group, with no difference in shoulder external rotation recovery between the groups (difference, 0.51 [95% confidence interval (CI), -0.31 to 1.33]). A greater proportion of the transfer group (24%) achieved an AMS score of >5 for shoulder external rotation compared with the grafting group (5%) (odds ratio, 5.9 [95% CI, 1.3 to 27.4]). Forty percent of the transfer group underwent a secondary shoulder surgical procedure compared with 53% of the grafting group; this was a significantly lower subsequent surgery rate (HR, 0.58 [95% CI, 0.35 to 0.95]).

CONCLUSIONS

Shoulder external rotation recovery in brachial plexus birth injury remains disappointing regardless of surgical technique, with a mean postoperative AMS score of 3, 17% of infants achieving an AMS score of >5, and a high frequency of secondary shoulder procedures in this study. Spinal accessory nerve to suprascapular nerve transfers were associated with a higher proportion of infants achieving functional shoulder external rotation (AMS score of >5) and fewer secondary shoulder procedures.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Microsurgery for Brachial Plexus Injury Before Versus After 6 Months of Age: Results of the Multicenter Treatment and Outcomes of Brachial Plexus Injury (TOBI) Study

BACKGROUND

Infants with more severe brachial plexus birth injury (BPBI) benefit from primary nerve surgery to improve function. The timing of the surgery, however, is controversial. The Treatment and Outcomes of Brachial Plexus Injury (TOBI) study is a multicenter prospective study with the primary aim of determining the optimal timing of this surgical intervention. This study compared outcomes evaluated 18 to 36 months after "early" microsurgery (at <6 months of age) with the outcomes of "late" microsurgery (at >6 months of age).

METHODS

Of 216 patients who had undergone microsurgery, 118 were eligible for inclusion because they had had a nerve graft and/or transfer followed by at least 1 physical examination during the 18 to 36-month interval after the microsurgery but before any secondary surgery. Patients were grouped according to whether the surgery had been performed before or after 6 months of age. Postoperative outcomes were measured using the total Active Movement Scale (AMS) score as well as the change in the AMS score. To address hand reinnervation, we calculated a hand function subscore from the AMS hand items and repeated the analysis only for the subjects with a Narakas grade of 3 or 4. Our hypothesis was that microsurgery done before 6 months of age would lead to better clinical outcomes than microsurgery performed after 6 months of age.

RESULTS

Eighty subjects (68%) had early surgery (at a mean age of 4.2 months), and 38 (32%) had late surgery (at a mean age of 10.7 months and a maximum age of 22.0 months). Infants who underwent early surgery presented earlier in life, had more severe injuries at baseline, and had a significantly lower postoperative AMS scores in the unadjusted analysis. However, when we controlled for the severity of the injury, the difference in the AMS scores between the early and late surgery groups was not significant. Similarly, when we restricted our multivariable analysis to patients with a Narakas grade-3 or 4 injury, there was no significant difference in the postoperative AMS hand subscore between the early and late groups.

CONCLUSIONS

This study suggests that surgery earlier in infancy (at a mean age of 4.2 months) does not lead to better postoperative outcomes of BPBI nerve surgery than when the surgery is performed later in infancy (mean age of 10.7 months).

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Proteasome inhibition preserves longitudinal growth of denervated muscle and prevents neonatal neuromuscular contractures

Muscle contractures are a prominent and disabling feature of many neuromuscular disorders, including the 2 most common forms of childhood neurologic dysfunction: neonatal brachial plexus injury (NBPI) and cerebral palsy. There are currently no treatment strategies to directly alter the contracture pathology, as the pathogenesis of these contractures is unknown. We previously showed in a mouse model of NBPI that contractures result from impaired longitudinal muscle growth. Current presumed explanations for growth impairment in contractures focus on the dysregulation of muscle stem cells, which differentiate and fuse to existing myofibers during growth, as this process has classically been thought to control muscle growth during the neonatal period. Here, we demonstrate in a mouse model of NBPI that denervation does not prevent myonuclear accretion and that reduction in myonuclear number has no effect on functional muscle length or contracture development, providing definitive evidence that altered myonuclear accretion is not a driver of neuromuscular contractures. In contrast, we observed elevated levels of protein degradation in NBPI muscle, and we demonstrate that contractures can be pharmacologically prevented with the proteasome inhibitor bortezomib. These studies provide what we believe is the first strategy to prevent neuromuscular contractures by correcting the underlying deficit in longitudinal muscle growth.

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.

Early Predictors of Microsurgical Reconstruction in Brachial Plexus Birth Palsy

BACKGROUND

Microsurgical reconstruction is indicated for infants with brachial plexus birth palsy (BPBP) that demonstrate limited spontaneous neurological recovery. This investigation defines the demographic, perinatal, and physical examination characteristics leading to microsurgical reconstruction.

METHODS

Infants enrolled in a prospective multicenter investigation of BPBP were evaluated. Microsurgery was performed at the discretion of the treating provider/center. Inclusion required enrollment prior to six months of age and follow-up evaluation beyond twelve months of age. Demographic, perinatal, and examination characteristics were investigated as possible predictors of microsurgical reconstruction. Toronto Test scores and Hospital for Sick Children Active Movement Scale (AMS) scores were used if obtained prior to three months of age. Univariate and multivariate logistic regression analyses were performed.

RESULTS

365 patients from six regional medical centers met the inclusion criteria. 127 of 365 (35%) underwent microsurgery at a median age of 5.4 months, with microsurgery rates and timing varying significantly by site. Univariate analysis demonstrated that several factors were associated with microsurgery including race, gestational diabetes, neonatal asphyxia, neonatal intensive care unit admission, Horner's syndrome, Toronto Test score, and AMS scores for finger/thumb/wrist flexion, finger/thumb extension, wrist extension, elbow flexion, and elbow extension. In multivariate analysis, four factors independently predicted microsurgical intervention including Horner's syndrome, mean AMS score for finger/thumb/ wrist flexion <4.5, AMS score for wrist extension <4.5, and AMS score for elbow flexion <4.5. In this cohort, microsurgical rates increased as the number of these four factors present increased from zero to four: 0/4 factors = 0%, 1/4 factors = 22%, 2/4 factors = 43%, 3/4 factors = 76%, and 4/4 factors = 93%.

CONCLUSIONS

In patients with BPBP, early physical examination findings independently predict microsurgical intervention. These factors can be used to provide counseling in early infancy for families regarding injury severity and plan for potential microsurgical intervention.Level of Evidence: Prognostic Level I.

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.

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.

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 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 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.

Medical Trainee Continuity of Care Following Emergency Department Consultations in a Pediatric Hospital

BACKGROUND

The importance of continuity of care in training is widely recognized; however, a broad-spectrum assessment across all specialties has not been performed.

OBJECTIVE

We assessed the continuity of care provided by trainees, following patient consultations in the emergency department (ED) across all specialties at a large pediatric tertiary care center.

METHODS

Medical records were reviewed to identify patients seen in consultation by a resident or fellow trainee in the ED over a 1-year period, and to determine if the patient followed up with the same trainee for the same condition during the next 6 months.

RESULTS

Resident and fellow trainees from 33 specialties participated in 3400 ED consultations. Approximately 50% (1718 of 3400) of the patients seen in consultation by a trainee in the ED followed up with the same specialty within 6 months, but only 4.1% (70 of 1718) followed up with the same trainee for the same condition. Trainee continuity of care ranged from 0% to 21% among specialties, where specialties with resident clinics (14.4%) have a greater continuity of care than specialties without resident clinics (2.7%, P < .001). Continuity of care did not differ between fellows (4.2%) and residents (4.0%, P = .87), but did differ between postgraduate years for residents (P < .001).

CONCLUSIONS

Trainee continuity of care for ED consultations was low across all specialties and levels of training. If continuity of care is important for patient well-being and trainee education, efforts to improve continuity for trainees must be undertaken.

Three-Dimensional Magnetic Resonance Imaging of Glenohumeral Dysplasia in Neonatal Brachial Plexus Palsy

BACKGROUND

Existing quantitative measurements of glenohumeral dysplasia in children with unresolved neonatal brachial plexus palsy (NBPP) have been mostly limited to the axial plane. The purpose of this study was to describe the three-dimensional (3D) pathoanatomy of glenohumeral dysplasia using 3D magnetic resonance imaging (MRI) reformations.

METHODS

3D MRI reformations of the scapula, glenoid labrum, and proximal part of the humerus were created from a volume-acquisition proton-density-weighted MRI sequence of both the affected and the unaffected shoulder of seventeen children less than six years of age with unresolved NBPP who had not undergone shoulder surgery. Glenoid retroversion and posterior humeral head displacement were measured on axial 2D images. Humeral head displacement in all planes, labral circumference, glenoid retroversion, glenoid declination, and scapular morphometric values were measured on 3D reformations. Contiguity of the humeral head with the labrum and the shape of the glenoid were classified. Measurements were compared between the affected and unaffected sides.

RESULTS

On 3D evaluation, the humeral head was completely posteriorly translated in ten patients but was never outside the glenoid labrum. Instead, in these patients, the humeral head was eccentrically articulating with the dysplastic glenoid and was contained by a posteriorly elongated labrum. Glenoid dysplasia was not limited to the axial plane. Less declination of the glenoid in the coronal plane correlated with greater 3D glenoid retroversion. Glenoid retroversion resulted from underdevelopment of the posterior aspect of the glenoid rather than overdevelopment of the anterior aspect of the glenoid. 3D measurements of greater glenoid retroversion and less declination correlated with 2D measurements of glenoid retroversion and posterior humeral head displacement.

CONCLUSIONS

Posterior humeral head displacement in NBPP should not be considered a simple "dislocation." Glenohumeral dysplasia is not limited to the axial plane. Abnormal glenoid declination may have potential implications for the evaluation and treatment of shoulder weakness and contractures.

Congenital Anomalies of the Hand--Principles of Management

Physicians who specialize in pediatric orthopedics and hand surgery frequently encounter congenital hand abnormalities, despite their relative rarity. The treating physician should be aware of the associated syndromes and malformations that may, in some cases, be fatal if not recognized and treated appropriately. Although these congenital disorders have a wide variability, their treatment principles are similar in that the physician should promote functional use and cosmesis for the hand. This article discusses syndactyly, preaxial polydactyly and post-axial polydactyly, and the hypoplastic thumb.

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.

Glenohumeral abduction contracture in children with unresolved neonatal brachial plexus palsy

BACKGROUND

Following neonatal brachial plexus palsy, the Putti sign-obligatory tilt of the scapula with brachiothoracic adduction-suggests the presence of glenohumeral abduction contracture. In the present study, we utilized magnetic resonance imaging (MRI) to quantify this glenohumeral abduction contracture and evaluate its relationship to shoulder joint deformity, muscle atrophy, and function.

METHODS

We retrospectively reviewed MRIs of the thorax and shoulders obtained before and after shoulder rebalancing surgery (internal rotation contracture release and external rotation tendon transfer) for twenty-eight children with unresolved neonatal brachial plexus palsy. Two raters measured the coronal positions of the scapula, thoracic spine, and humeral shaft bilaterally on coronal images, correcting trigonometrically for scapular protraction on axial images. Supraspinatus, deltoid, and latissimus dorsi muscle atrophy was assessed, blinded to other measures. Correlations between glenohumeral abduction contracture and glenoid version, humeral head subluxation, passive external rotation, and Mallet shoulder function before and after surgery were performed.

RESULTS

MRI measurements were highly reliable between raters. Glenohumeral abduction contractures were present in twenty-five of twenty-eight patients, averaging 33° (range, 10° to 65°). Among those patients, abductor atrophy was present in twenty-three of twenty-five, with adductor atrophy in twelve of twenty-five. Preoperatively, greater abduction contracture severity correlated with greater Mallet global abduction and hand-to-neck function. Abduction contracture severity did not correlate preoperatively with axial measurements of glenohumeral dysplasia, but greater glenoid retroversion was associated with worse abduction contractures postoperatively. Surgery improved passive external rotation, active abduction, and hand-to-neck function, but did not change the abduction contracture.

CONCLUSIONS

A majority of patients with persistent shoulder weakness following neonatal brachial plexus palsy have glenohumeral abduction deformities, with contractures as severe as 65°. The abduction contracture occurs with abductor atrophy, with or without associated adductor atrophy. This contracture may improve global shoulder abduction by positioning the glenohumeral joint in abduction. Glenohumeral and scapulothoracic kinematics and muscle pathology must be further elucidated to advance an understanding of the etiology and the prevention and treatment of the complex shoulder deformity following neonatal brachial plexus palsy.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Median and/or Ulnar Nerve Fascicle Transfer for the Restoration of Elbow Flexion in Upper Neonatal Brachial Plexus Palsy

Introduction

Transfer of a fascicle of the ulnar and/or median nerve to the musculocutaneous nerve in order to reinnervate the biceps and/or brachialis muscles has a high success rate and a low rate of complications in infants with upper (C5-C6) or extended upper (C5-C7) neonatal brachial plexus palsy.

Step 1 Make the Incision

Make a longitudinal incision along the midline of the middle third of the medial brachium.

Step 2 Mobilize the Musculocutaneous Nerve

The musculocutaneous nerve is typically found on the undersurface of the biceps muscle.

Step 3 Mobilize the Median Nerve

The median nerve runs along the neurovascular sheath medial to the brachial artery.

Step 4 Mobilize the Ulnar Nerve

The ulnar nerve lies posterior to the intermuscular septum.

Step 5 Transfer the Donor Nerve to the Recipient Nerve

Cut the donor fascicles distally and the recipient fascicles proximally to facilitate transfer.

Step 6 Close the Wound

Irrigate the wound, and close it in layers.

Step 7 Postoperative Protocol

Remove the bandages two weeks postoperatively, and encourage passive range-of-motion exercises.

Results

In our series, thirty-one patients underwent single or combined nerve fascicle transfer; twenty-seven (87%) obtained functional elbow flexion recovery (Active Movement Scale [AMS] score ≥ 6) while twenty-four (77%) obtained full elbow flexion recovery (AMS score = 7). Indications Contraindications Pitfalls & Challenges.

The relationship between medical malpractice litigation and parent reports of patient function following neonatal brachial plexus palsy

BACKGROUND

The increasing use of patient-reported outcome measures in clinical research and care across all medical disciplines requires an understanding of the nonclinical variables that affect these measures. Participation in medical malpractice litigation, as is common following neonatal brachial plexus palsy, may be an important confounder of parent or patient-reported outcomes.

METHODS

This multicenter, case-control study includes patients two to eighteen years of age with neonatal brachial plexus palsy seen at three tertiary brachial plexus centers from January 1990 to December 2011. Public court records were searched for litigation details. Families with and without medical malpractice litigation were matched on age and injury severity (by Raimondi scale and Mallet classification). Parent or patient-reported outcomes, measured by the Pediatric Outcomes Data Collection Instrument, were compared between litigation and non-litigation cohorts.

RESULTS

Of 334 patients from eighteen states, seventy-five (22%) were plaintiffs in medical malpractice lawsuits. When matched on patient age and injury severity, parents reported their children to have worse mobility (p = 0.04), sports or physical function (p = 0.003), and global function (p = 0.02) in the litigation cohort compared with the non-litigation cohort. Parents in active lawsuits reported their children to have greater pain (p = 0.046) compared with children of parents in closed lawsuits, when controlling for patient age and injury severity. Outcomes scores simultaneously obtained from patients and parents differed in the litigation cohort, with parents reporting their children to have worse upper-extremity function (p = 0.03) and global function (p = 0.008) than their children reported.

CONCLUSIONS

Litigation is associated with worse parent reports of children's function and pain following neonatal brachial plexus palsy, independent of age, injury severity, and the patients' own report of their function. Litigation status should be considered a confounding variable in the use of parent-reported outcomes in neonatal brachial plexus palsy research. Parents involved in litigation may benefit from additional support.

Hand function and quality of life in children with epidermolysis bullosa

Patient-reported outcomes are becoming increasingly important to clinical care. Epidermolysis bullosa (EB), a rare genetic skin disorder, can result in severe hand impairment, but parent and patient perceptions of hand function have never been assessed. This study aimed to quantify parent- and patient-reported hand function and assess its relationship with quality of life (QOL) in children with EB. This cross-sectional study included children with EB treated at an interdisciplinary EB center. Hospital records were searched for demographic characteristics and medical history. Eligible families were invited to complete two surveys by mail or telephone. The ABILHAND-Kids questionnaire assessed manual hand ability for 21 functions. The Quality of Life in Epidermolysis Bullosa questionnaire assessed EB-related QOL. Hand function and QOL of various subtypes were compared using Mann-Whitney tests. Seventy-one parents and patients ages 2 to 18 years with EB from 20 states in the United States completed questionnaires. Children with recessive dystrophic EB reported the worst hand function and QOL. Bimanual functions involving finger mobility were the most challenging for all EB subtypes. QOL was highly related to the degree of hand function, being correlated with 20 of the 21 individual hand functions and most associated with the ability to perform unimanual functions. Parent- and patient-reported hand function can be measured in children with EB using the ABILHAND-Kids questionnaire. Hand impairment is strongly associated with worse QOL, probably due to difficulty performing daily activities. The effect of interventions such as hand surgery could be prospectively evaluated using this questionnaire.

A stepwise algorithm for surgical treatment of type II displaced pediatric phalangeal neck fractures

PURPOSE

To evaluate a stepwise reduction algorithm including closed, percutaneous, and open reduction techniques followed by percutaneous pin fixation for displaced pediatric phalangeal neck fractures.

METHODS

Sixty-one consecutive children (mean age, 9.4 y; range, 2-18 y) presenting with closed, type II displaced phalangeal neck fractures were treated using the following algorithm. If satisfactory reduction was achieved with closed reduction, percutaneous pinning (CRPP) was performed. If not achieved, then percutaneous reduction and pinning (PRPP) was performed using a temporary intrafocal joystick for reduction and for osteoclasis as needed. If percutaneous reduction failed, open reduction and percutaneous pinning (ORPP) was performed. Using the Al-Qattan system, radiographic and clinical outcomes were retrospectively graded for union, deformity, range of motion, and function.

RESULTS

Satisfactory alignment was achieved in all 61 fractures, by CRPP in 49 and PRPP in 12. No fracture required open reduction. Mean number of days from injury to surgery was 8 days for CRPP and 17 days for PRPP. All fractures treated after 13 days required percutaneous pinning. Fifty-three patients were followed for at least 1 year or until full functional recovery was achieved, with 45 excellent, 4 good, 1 fair, and 3 poor results. Four complications accounted for the fair and poor results, including 1 flexion contracture, 1 nonunion following pin track infection, and 1 case of avascular necrosis following a severe crush injury in the CRPP group and 1 flexion contracture following PRPP.

CONCLUSIONS

Our stepwise algorithm for surgical treatment of closed, type II displaced pediatric phalangeal neck fractures produced 92% good to excellent results while minimizing the need for open reduction even in late-presenting fractures.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Early functional recovery of elbow flexion and supination following median and/or ulnar nerve fascicle transfer in upper neonatal brachial plexus palsy

BACKGROUND

Nerve transfers using ulnar and/or median nerve fascicles to restore elbow flexion have been widely used following traumatic brachial plexus injury, but their utility following neonatal brachial plexus palsy remains unclear. The present multicenter study tested the hypothesis that these transfers can restore elbow flexion and supination in infants with neonatal brachial plexus palsy.

METHODS

We retrospectively reviewed the cases of thirty-one patients at three institutions who had undergone ulnar and/or median nerve fascicle transfer to the biceps and/or brachialis branches of the musculocutaneous nerve after neonatal brachial plexus palsy. The primary outcome measures were postoperative elbow flexion and supination as measured with the Active Movement Scale (AMS). Patients were followed for at least eighteen months postoperatively unless they obtained full elbow flexion or supination (AMS = 7) prior to eighteen months of follow-up.

RESULTS

Twenty-seven (87%) of the thirty-one patients obtained functional elbow flexion (AMS ≥ 6), and twenty-four (77%) obtained full recovery of elbow flexion against gravity (AMS = 7). Of the twenty-four patients for whom recovery of supination was recorded, five (21%) obtained functional recovery. Combined ulnar and median nerve fascicle transfers were performed in five patients and resulted in full recovery of elbow flexion against gravity and supination of AMS ≥ 5 for all five. Single-fascicle transfer was performed in twenty-six patients and resulted in functional flexion in 85% (twenty-two of twenty-six) and functional supination in 15% (three of twenty). Patients with nerve root avulsion were treated at a younger age (p < 0.01), had poorer preoperative elbow flexion (p < 0.01), and recovered greater supination (p < 0.01) compared with patients with dissociative recovery. Younger patients (p < 0.01) and patients with C5-C6 avulsion (p < 0.02) recovered the greatest supination. One patient sustained a transient anterior interosseous nerve palsy after median nerve fascicle transfer.

CONCLUSIONS

Ulnar and/or median nerve fascicle transfers were able to effectively restore functional elbow flexion in patients with nerve root avulsion, dissociative recovery, or late presentation following neonatal brachial plexus palsy. Recovery of supination was less, with greater success noted in younger patients with nerve root avulsion.

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.

Clinical research fails to support more aggressive management of pediatric upper extremity fractures

BACKGROUND

Recent years have seen a trend toward more operative treatment of upper extremity fractures in children. The current study examines clinical research regarding pediatric upper extremity fracture treatment over the past twenty years in an attempt to identify research-based support for the increasingly aggressive treatment of these fractures.

METHODS

Accepted abstracts on pediatric upper extremity fracture treatment presented at the Pediatric Orthopaedic Society of North America (POSNA) and the American Academy of Orthopaedic Surgeons (AAOS) annual meetings from 1993 through 2012 were reviewed. Abstracts were chosen rather than publications because of the larger number of abstracts that are available and because abstracts offer a more global representation of the research being performed by and presented to the members of these societies. The treatment recommendations of authors were classified as more aggressive, less aggressive, or neutral by two attending surgeons on the basis of which treatment was favored in comparative studies or how treatments in single-group studies compared with the standard of care at the time. Abstracts without treatment recommendations were excluded. Relationships between level of evidence, fracture location, and treatment recommendation were statistically evaluated with use of Spearman correlations and logistic regression analysis.

RESULTS

Overall, a higher proportion of studies gave less aggressive (47%, ninety of 190) or neutral (27%, fifty-one of 190) recommendations than more aggressive treatment recommendations (26%, forty-nine of 190). Only 24% of operative studies and 11% of nonoperative studies recommended more aggressive treatment (p = 0.001). Case series were more likely to recommend more aggressive treatments than comparative studies (30% versus 17%, p = 0.025). Also, studies with a smaller sample size were more likely to recommend more aggressive treatments (p = 0.006). The great majority of level-I and level-II (91%, ten of eleven), level-III (81%, thirty-nine of forty-eight), and level-IV (70%, ninety-two of 131) studies, however, provided either neutral or less-aggressive treatment recommendations.

CONCLUSIONS

The majority of research presented at POSNA and AAOS meetings over the past two decades fails to support the trend toward increasingly aggressive treatment of pediatric upper extremity fractures. This dichotomy between clinical research and the direction of clinical treatment must be explored in our efforts to provide evidence-based care of pediatric upper extremity fractures.

Quantification of humeral head deformity following neonatal brachial plexus palsy

BACKGROUND

Neonatal brachial plexus palsy frequently leads to glenohumeral dysplasia if neurological recovery is incomplete. Although glenoid retroversion and glenohumeral subluxation have been well characterized, humeral head deformity has not previously been quantified. Nonetheless, humeral head flattening is described as a contraindication to joint contracture release and external rotation tendon transfers. This study describes a novel technique for objectively quantifying humeral head deformity with use of magnetic resonance (MR) imaging and correlates the humeral head deformity with clinical and radiographic outcomes following joint rebalancing surgery.

METHODS

Magnetic resonance images of thirty-two children (age, 0.7 to 11.5 years) with neonatal brachial plexus palsy were retrospectively reviewed. Passive shoulder external rotation and Mallet scores were reviewed before joint rebalancing surgery and at a minimum clinical follow-up interval of two years. The humeral head skewness ratio on preoperative and postoperative axial MR images was defined as the ratio of anterior to posterior humeral head area, and this ratio was compared between affected and unaffected shoulders and with the glenoid version angle, posterior subluxation of the humeral head, and clinical parameters before and after surgery with use of paired t tests and Spearman correlation. Intraobserver and interobserver reliability of MR image measurements was determined.

RESULTS

Measurements of the skewness ratio on the affected side had moderate to substantial intraobserver reliability (0.53 to 0.72) and substantial interobserver reliability (0.65 to 0.71). Preoperatively, the skewness ratio of the affected humeral head (mean, 0.76; range, 0.54 to 1.03) differed significantly from the ratio in the contralateral shoulder (p<0.05) and was significantly associated with the glenoid version angle (p<0.05) and posterior subluxation of the humeral head (p<0.05). Remodeling of the affected humeral head was observed postoperatively, with a significant improvement in the skewness ratio (p<0.05). However, there were no significant correlations between the preoperative skewness ratio and postoperative clinical outcomes.

CONCLUSIONS

Humeral head deformity in neonatal brachial plexus palsy correlated with other measures of glenohumeral dysplasia and could be reliably and objectively quantified on MR imaging with use of the skewness ratio. The humeral head deformity can remodel following joint rebalancing surgery, and such a deformity alone does not preclude a successful outcome after surgical attempts to restore glenohumeral congruity.

The effects of denervation, reinnervation, and muscle imbalance on functional muscle length and elbow flexion contracture following neonatal brachial plexus injury

The pathophysiology of paradoxical elbow flexion contractures following neonatal brachial plexus injury (NBPI) is incompletely understood. The current study tests the hypothesis that this contracture occurs by denervation-induced impairment of elbow flexor muscle growth. Unilateral forelimb paralysis was created in mice in four neonatal (5-day-old) BPI groups (C5-6 excision, C5-6 neurotomy, C5-6 neurotomy/repair, and C5-T1 global excision), one non-neonatal BPI group (28-day-old C5-6 excision), and two neonatal muscle imbalance groups (triceps tenotomy ± C5-6 excision). Four weeks post-operatively, motor function, elbow range of motion, and biceps/brachialis functional lengths were assessed. Musculocutaneous nerve (MCN) denervation and reinnervation were assessed immunohistochemically. Elbow flexion motor recovery and elbow flexion contractures varied inversely among the neonatal BPI groups. Contracture severity correlated with biceps/brachialis shortening and MCN denervation (relative axon loss), with no contractures occurring in mice with MCN reinnervation (presence of growth cones). No contractures or biceps/brachialis shortening occurred following non-neonatal BPI, regardless of denervation or reinnervation. Neonatal triceps tenotomy did not cause contractures or biceps/brachialis shortening, nor did it worsen those following neonatal C5-6 excision. Denervation-induced functional shortening of elbow flexor muscles leads to variable elbow flexion contractures depending on the degree, permanence, and timing of denervation, independent of muscle imbalance.

CT evaluation of extensor tendon entrapment as a complication of a distal radial fracture in a child

Extensor indicis proprius (EIP) entrapment is a rare complication of a distal radial fracture. We report an 11-year-old with limited flexion of her index finger 1 year after a distal radial fracture. The utility of cross-sectional imaging in the diagnosis and preoperative planning of this complication is presented.

Impaired growth of denervated muscle contributes to contracture formation following neonatal brachial plexus injury

BACKGROUND

The etiology of shoulder and elbow contractures following neonatal brachial plexus injury is incompletely understood. With use of a mouse model, the current study tests the novel hypothesis that reduced growth of denervated muscle contributes to contractures following neonatal brachial plexus injury.

METHODS

Unilateral brachial plexus injuries were created in neonatal mice by supraclavicular C5-C6 nerve root excision. Shoulder and elbow range of motion was measured four weeks after injury. Fibrosis, cross-sectional area, and functional length of the biceps, brachialis, and subscapularis muscles were measured over four weeks following injury. Muscle satellite cells were cultured from denervated and control biceps muscles to assess myogenic capability. In a comparison group, shoulder motion and subscapularis length were assessed following surgical excision of external rotator muscles.

RESULTS

Shoulder internal rotation and elbow flexion contractures developed on the involved side within four weeks following brachial plexus injury. Excision of the biceps and brachialis muscles relieved the elbow flexion contractures. The biceps muscles were histologically fibrotic, whereas fatty infiltration predominated in the brachialis and rotator cuff muscles. The biceps and brachialis muscles displayed reduced cross-sectional and longitudinal growth compared with the contralateral muscles. The upper subscapularis muscle similarly displayed reduced longitudinal growth, with the subscapularis shortening correlating with internal rotation contracture. However, excision of the external rotators without brachial plexus injury caused no contractures or subscapularis shortening. Myogenically capable satellite cells were present in denervated biceps muscles despite impaired muscle growth in vivo.

CONCLUSIONS

Injury of the upper trunk of the brachial plexus leads to impaired growth of the biceps and brachialis muscles, which are responsible for elbow flexion contractures, and impaired growth of the subscapularis muscle, which correlates with internal rotation contracture of the shoulder. Shoulder muscle imbalance alone causes neither subscapularis shortening nor internal rotation contracture. Impaired muscle growth cannot be explained solely by absence of functioning satellite cells.

Pediatric phalanx fractures: unique challenges and pitfalls

The hand is the most frequently injured part of the body in children. Most pediatric hand fractures can be treated by nonoperative means with good results. However, a subset of fractures requires prompt recognition and surgical intervention. We will review several pediatric phalangeal fracture types that must be recognized and treated appropriately to minimize complications and disability. These injuries defy the general conception that pediatric fractures universally do well with minimal intervention. This paper highlights two important concepts: (1) phalangeal fractures in children can differ considerably from other pediatric fractures, and (2) phalangeal fractures in children can be very different from those in adults. Tolerance of displacement may be small in juxtaarticular or intraarticular fractures and healing is rapid in phalangeal fractures, allowing displaced fractures to develop into malunions in a short period of time, with resultant deformity and dysfunction. Careful clinical examination of any suspected phalanx fracture in children is essential to appropriate treatment of these potentially problematic injuries, including adequate radiographic evaluation with multiple views of the suspected fracture site and thorough examination of possible open injuries.

LEVEL OF EVIDENCE

Therapeutic study, level V (expert opinion).