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.

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 ß2 -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 ß-adrenergic stimulation. Intriguingly, the robust alterations in CSA occurred with minimal changes to normal longitudinal muscle growth as determined by sarcomere length. Instead, ß-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.

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.

Brachial plexus birth injury's scope of impact in adulthood is broad, covering every aspect of HRQoL.The focus of rehabilitation for brachial plexus birth injury (BPBI) through the lifespan should extend beyond improving physical musculoskeletal function and include comprehensive support for physical, emotional, social, and life role concerns.Brachial plexus birth injury's nature of impact in adulthood varies among individuals within each aspect of health-related quality of life.The variability of BPBI's impact in adulthood underscores the need for individualized, patient-centered assessment and rehabilitative care.

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.

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.

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.

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.

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).

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.

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 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.

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.

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.

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.