Outcome of subscapularis muscle release for shoulder contracture secondary to brachial plexus palsy at birth

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.

Subscapularis Z-plasty With Coracoidectomy for Internal Rotation Contracture in Children With Brachial Plexus Birth Injury

OBJECTIVES

Brachial plexus birth injury (BPBI) is a rare dystocia complication. Although it has a good prognosis, a significant number retain functional impairment to varying degrees. The data concerning shoulder function improvement and complication rates are conflicting due to variations in outcome measures between the studies. Therefore, we report our experience with this approach.

METHODS

It was a retrospective study conducted at King Faisal Specialist Hospital and Research Center in Riyadh (FSH&RC), Saudi Arabia. Data such as patient demographics, Mallet scores, and passive external rotation (PER) in adduction and abduction were retrieved from the medical records.

RESULTS

In active shoulder function, Mallet score significantly improved (P=0.00). The improvement was most remarkable in active external rotation movement (P=0.00) followed by hand to the neck. However, no significant gain was observed in active abduction and hand-to-back. At the final follow-up, with a mean of 2.9 years, the improvement in PER in adduction and abduction was maintained. Compared to six months postoperative, no significant difference was found in hand-to-neck, hand-to-back, and total Mallet score.

CONCLUSION

Subscapularis z-lengthening with coracoidectomy was consistently effective in correcting internal rotation contraction in a patient with BPBI. Significant improvements were observed in the Mallet score and PER in adduction and abduction.

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.

Brachial Plexus Birth Injuries

Brachial plexus birth injuries (BPBIs) are typically traction type injuries to the newborn that occur during the delivery process. Although the incidence of these injuries has overall decreased from 1.5 to around 0.9 per 1000 live births in the United States over the past 2 decades, these injuries remain common, with incidence holding fairly steady from 2008 to 2014. Shoulder dystocia is the strongest identified risk factor, imparting a 100-fold greater risk. The newborn's shoulder is caught behind the mother's pubic bone, and traction performed on the child during delivery results in injury to the brachial plexus. Other risk factors associated with BPBI include macrosomia (birthweight > 4.5 kg), heavy for gestational age infants, birth hypoxia, gestational diabetes, and forceps or vacuum-assisted delivery. Breech presentation has also been described as a risk factor in the past, but there have been more recent data that challenge this association.

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.

Effect of arthroscopic shoulder release on shoulder mobility and bone deformity following brachial plexus birth injury: a systematic review and meta-analysis

BACKGROUND

Specific information to guide clinical practice is lacking for the effects of arthroscopic release on bone and joint deformities, as well as the additional benefits of tendon transfer, in children with brachial plexus birth injury. The aims of this study were (1) to evaluate changes in shoulder mobility and bone and joint deformity, (2) to evaluate the effect of release with and without tendon transfer on the same outcomes, and (3) to evaluate the perioperative and long-term complications.

METHODS

We conducted a systematic review and meta-analysis. Four databases were searched using relevant inclusion and exclusion criteria from inception until May 2020. The quality of articles was evaluated using the Methodological Index for Non-randomized Studies (MINORS) scale. Data regarding patients, interventions, and clinical and radiologic outcomes were reported.

RESULTS

Thirteen articles were included: 6 of low quality and 7 of moderate quality separated into 17 studies (266 children). The mean follow-up duration was 32.4 months (standard deviation, 15.2 months). Arthroscopic release significantly improved the Mallet score (standardized mean difference [SMD], 3.1 [95% confidence interval (CI), 1.5-4.7]; P < .001) and passive external rotation (SMD, 3.6 [95% CI, 2.3-4.9]; P = .02). The percentage of humeral head anterior (SMD, 1.3 [95% CI, 0.7-1.9]; P = .003) and glenoid retroversion (SMD, 1.4 [95% CI, 0.9-2]; P = .01) also improved. Descriptive analysis of the data suggested that concomitant tendon transfer further improved mobility. Recurrence of internal-rotation contracture was reported in 8 of 157 children.

DISCUSSION

This systematic review showed that arthroscopic release effectively improves both shoulder mobility and bone deformity, with few complications in young children with brachial plexus birth injury. As such, it seems reasonable to propose a stepwise approach starting with a release without transfer.

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.

Minimally Invasive Subscapularis Release: A Novel Technique and Results

BACKGROUND

Shoulder imbalance secondary to residual brachial plexus birth palsy requires release of internal rotation contracture and tendon transfer. Subscapularis is considered as the prime element of internal rotation contracture and various methods have been described for subscapularis lengthening. It includes open subscapularis slide or lengthening and arthroscopic release. We hypothesized that subscapularis can be released through minimally invasive approach from the medial border of scapula and thus avoiding formal open procedures and risk of weakening the internal rotation strength.

METHODS

Safety zones to avoid injury to important neurovascular structures while performing minimally invasive subscapularis release (MISR) were determined through cadaveric dissection. Between 2014 and 2016, 45 patients underwent MISR. A concomitant conjoined Latissimus Dorsi and Teres Major transfer was performed. Twenty patients with minimum 2-year follow-up were included in this study. Average age of patients was 6.4 years. A 5-point modified Mallet Score, degrees of active and passive rotations and abduction were used as outcome measures. Axial MRI imaging were available to classify the gleno-humeral deformity.

RESULTS

Mean improvement in passive external rotation was 80 degrees and in active external rotation was 43 degrees (P <0.001) at 3 months, which was maintained at final follow-up. Average shoulder abduction improved from preoperative-101 degrees to postoperative-142 degrees. Aggregate 5-point Mallet Score improved from 12.8 points (range, 11 to 16) preoperatively to 18.5 points (range, 16 to 21) postoperatively. None of the patients developed external rotation contracture. The results were comparable with other existing techniques of subscapularis release with conjoint tendon transfer.

CONCLUSIONS

MISR with conjoined tendon transfer is an effective way of treating internal rotation contracture in children with congruent glenohumeral joints. This procedure has shown beneficial outcomes even in patients with noncongruous glenohumeral joints, when performed in children younger than 4 years. Advantages of MISR include less risk to neurovascular structures, minimal soft tissue trauma, directly addressing the medial tight subscapularis fibers, significantly less surgical time and minimum learning curve.

LEVELS OF EVIDENCE

Level III-retrospective comparative study.

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.

Preoperative multislice computed tomography evaluation of shoulder deformities in brachial plexus birth palsy patients undergoing tendon transfer

BACKGROUND

Brachial plexus birth palsy (BPBP) refers to a birth related paralysis of the upper extremity. The current study was designed to evaluate the efficacy of computed tomography (CT) in the assessment of humeral head posterior subluxation and glenoid retroversion preoperatively and to evaluate whether or not bony deformity correlates with functional improvement (based on Modified Mallet Score) following tendon transfer in brachial plexus birth palsy patients.

PATIENTS AND METHODS

This prospective study included 30 patients, 15 below 4 years and 15 above 4 years old, with a mean age 3.65 ± 1.39 (range 2-8) years old. Thirteen patients were males (43.3%) and 17 were females (56.6%). The left side was affected in 13 patients (43.3%), while the right in 17 (56.7%). The Modified Mallet Score was used for clinical assessment of the shoulder function. A multislice CT scan with 3D reconstruction was used as a preoperative radiological assessment of the shoulder. An electromyography (EMG) of the muscles around the shoulder was performed. All patients were operated upon by anterior release of the internal rotators to improve the external rotation range of motion and by transfer of teres major and latissimus dorsi to improve the abduction motion through one anterior deltopectoral incision and a small posterosuperior incision. Postoperatively, the range of shoulder abduction and external rotation had been assessed after shoulder spica removal and till the end of follow up.

RESULTS

Fourteen patients (46.7%) had a normal glenoid version angle (normal range from -12° to 2°) and normal range of articulation with the glenoid (42.3%-71.4%) and 16 patients (53.3%) had an abnormal glenoid version angle and abnormal range of articulation with the glenoid. According to the Modified Mallet Score, there was a statistically significant difference in the mean value of global abduction (P = 0.04), external rotation (P = 0.03), hand to mouth (P = 0.02), hand to neck (P = 0.03) and hand to spine (P = 0.02) between the pre- and post-operative assessment of all patients. There was a statistically significant difference in the mean value of postoperative Modified Mallet Score between the patients under the age of 4 years and those above the age of 4 years. There was no statistically significant difference between the patients with normal CT angles and those with abnormal CT angles. There was no statistically significant difference in the mean value of glenoid version angle and percentage of humeral head articulation between the patients below the age of 4 years and those above 4 years (P = 0.845).

CONCLUSION

The study concluded that the glenoid version angle and humeral head articulation percentage do not negatively affect results of the tendon transfer around the shoulder in patients of upper brachial plexus birth palsy.

LEVEL OF EVIDENCE

IV.

Isolated open anterior shoulder release in brachial plexus birth palsy

BACKGROUND

In children with brachial plexus birth palsy (BPBP), a shoulder joint internal contracture is commonly observed, which may result in glenohumeral osseous deformities and posterior joint subluxation. The purpose of this retrospective study was to evaluate the impact of an isolated anterior shoulder release on osteoarticular disorders and assess the subsequent clinical improvements.

METHODS

Forty consecutive BPBP patients with glenohumeral dysplasia underwent an open anterior shoulder release. Shoulder scans (ie, magnetic resonance imaging preoperatively and computed tomography postoperatively) were conducted to assess glenoid version and the percentage of the humeral head anterior to the middle of the glenoid fossa. Clinical data including analytical shoulder range of motion and modified Mallet scores were collected.

RESULTS

After a mean follow-up period of 23 months, glenoid version and the percentage of the humeral head anterior to the middle of the glenoid fossa significantly improved from -32° and 18%, respectively, to mean postoperative values of -12° (P < .001) and 45% (P < .001), respectively. Passive and active external rotation increased from -2° and -43°, respectively, to 76° (P < .001) and 54° (P < .001), respectively. The mean modified Mallet score significantly improved from 14.2 to 21.4 points (P < .001). In 8 children with satisfactory passive motion, a latissimus dorsi transfer was performed secondarily to obtain satisfactory active motion.

CONCLUSION

In BPBP patients with glenohumeral deformities, isolated open anterior release of the shoulder induces significant remodeling of the joint, reducing posterior joint subluxation and improving both passive and active shoulder ranges of motion. Additional latissimus transfer remains mandatory in selected cases to achieve satisfactory function.

Lower Trapezius Transfer for Patients With Brachial Plexus Injury

BACKGROUND

Brachial plexus injury is a complex entity that often results in partial recovery. Most studies to date have focused on improving shoulder abduction. However, a recent technique has been outlined-one that transfers the lower trapezius to improve the external rotation of the shoulder. The primary objective of this study was to evaluate the gains in external rotation of the shoulder in patients who have undergone transfer of the lower trapezius; secondarily, we assessed the range of motion in the elbow and shoulder joints, as well as the muscle strength and quality of life.

METHODS

This article presents a prospective cohort study of 10 patients who underwent transfer of the lower trapezius. During the preoperative period and at 6 months after the operation, both active and passive goniometric measurements were assessed, as were muscle strength, Mallet's classification, and patients' responses to the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire.

RESULTS

External rotation exhibited an improvement of 17° in the active range of motion and 14° the passive range, which was not statistically significant. Flexion and active abduction of the shoulder, as well as the responses to the DASH, showed positive results. The Mallet's classification and muscle strength measurement results were not significant.

CONCLUSIONS

The procedure might be an alternative for restoration of shoulder function and glenohumeral stabilization and mainly to improve quality of life. However, additional studies are required to define and refine this surgical technique.

Motion Necessary to Achieve Mallet Internal Rotation Positions in Children With Brachial Plexus Birth Palsy

BACKGROUND

Upper extremity function in children with brachial plexus birth palsy (BPBP) is assessed with clinical tests such as the Mallet classification, which uses a hand to spine position to assess shoulder internal rotation, or the modified Mallet classification, which adds an additional internal rotation task (hand to belly). Children with BPBP frequently have difficulty performing the hand to spine task. This study compared scapulothoracic and glenohumeral (GH) parameters associated with successful completion of the hand to spine and hand to belly modified Mallet positions.

METHODS

Motion capture measurement of 32 children with BPBP was performed in hand on spine, internal rotation (hand to belly), hand to mouth, and maximal humerothoracic extension positions. Modified Mallet scores were determined by a hand surgeon.

RESULTS

Children with better hand to spine performance demonstrated significantly greater GH extension and a nonsignificant trend toward increased GH internal rotation compared with children with scores <3. Children with better internal rotation position performance demonstrated significantly greater GH internal rotation and no significant difference in GH extension. Hand on spine and internal rotation Mallet scores moderately correlated (Pearson r=0.469); however, 54% of children who could place their palms flat on their bellies could not reach behind their backs.

CONCLUSIONS

Successfully reaching behind one's back requires both internal rotation and extension, representing a multiplanar motion. The hand to belly performance is less affected by extension and should be considered for internal rotation assessment, particularly for children undergoing surgical intervention that may affect internal rotation.

LEVEL OF EVIDENCE

Level II.

Kinematic differences between children with obstetric brachial plexus palsy and healthy controls while performing activities of daily living

BACKGROUND

Residual shoulder dysfunction and deformity impacts on functional performance in children with obstetric brachial plexus palsy. Clinical understanding of upper limb dynamic movement patterns is difficult with observation alone. This case-control study describes the significant kinematic differences between children with obstetric brachial plexus palsy compared to typically developing children while performing tasks of the modified Mallet Scale.

METHODS

Eleven children with obstetric brachial plexus palsy (mean 10 years, range 7-15 years, Narakas group I-III) and 10 typically developing children (mean 9 years 9 months, range 6-15 years) completed three-dimensional upper limb motion analysis using the acromion method to track dynamic scapular movement. Kinematic data were captured by a 4-CODA cx1 optoelectronic tracking system. Participants performed three trials of the modified Mallet scale tasks. Local coordinate systems, segment and joint rotations were defined as recommended by the International Society of Biomechanics.

FINDINGS

Joint rotation angles against time of the glenohumeral, thoracohumeral and scapulohumeral joints were calculated. Kinematic findings demonstrated increased internal rotation in all postures, reduced glenohumeral excursion, habitual "trumpet" posture of glenohumeral abduction/elevation and variability in movement strategies. Scapulohumeral rhythm during abduction task was 1.88:1 in typically developing children and 1.04:1 in children with obstetric brachial plexus palsy.

INTERPRETATION

Children with obstetric brachial plexus palsy demonstrate deficient external rotation in all tasks. Despite increased postural internal rotation, ability to move through internal rotation range is compromised. The glenohumeral joint showed the greatest range deficit, contributing to abnormal scapulohumeral rhythm. Future sub-group analysis of Narakas Classification is recommended.

Transfer of Pectoralis Major to Subscapularis in the Management of Brachial Plexus Birth Palsy Sequels

BACKGROUND

Limitations in abduction and external rotation are the sequel of brachial palsy. The purpose of this study was to evaluate functional outcomes of modified L'Episcopo procedure in children with brachial palsy who do not have gross shoulder joint subluxation.

METHODS

From 2002 to 2012, a continuous series of 22 patients with brachial plexus birth palsy underwent a modified L'Episcopo procedure. Through an axillary approach, subscapularis release with latissimus dorsi rerouting and transfer of pectoralis major to subscapularis footprint was performed.

RESULTS

The mean age of patients at surgery was 49 months. The mean follow-up time was 51 months (range, 24 to 90 mo). Preoperatively, the mean active abduction and external rotation were 77.5 and 2.5 degrees, respectively. The mean active abduction and external rotation were 135.6 and 32 degrees, respectively, at the final follow-up (P<0.001).

CONCLUSIONS

This modified L'Episcopo technique is an effective and reproducible procedure that improves shoulder function significantly.

LEVEL OF EVIDENCE

Level III.

Reliability of 3D upper limb motion analysis in children with obstetric brachial plexus palsy

Kinematics, measured by 3D upper limb motion analysis (3D-ULMA), can potentially increase understanding of movement patterns by quantifying individual joint contributions. Reliability in children with obstetric brachial plexus palsy (OBPP) has not been established.

OBJECTIVE

This study aimed to determine between session reliability and measurement errors of 3D-ULMA using the acromion method (AM) in children with OBPP.

APPROACH

Ten participants (mean 10 years, range 7-15 years, Narakas classification I-III) completed 3D-ULMA on two occasions, mean interval of 8.6 d (±2.8 d). Kinematic data were captured by a 4-CODA cx1 optoelectronic tracking system. Participants performed three trials of the modified Mallet scale tasks. Local coordinate systems, segment and joint rotations were defined as recommended by the International Society of Biomechanics. The intraclass correlation coefficient (ICC 2,K) and standard error of measurement (SEM) were calculated for task duration, range and joint angle at point of task achievement (PTA).

MAIN RESULTS

Results indicated poor reliability for spatiotemporal parameters and range. Moderate to excellent reliability at PTA was observed in 19/60 variables (ICC: 0.77-0.98; SEM: 3.5°-10.4°). The Abduction Task had the highest (ICC: 0.79-0.98; SEM: 3.5°-10.3°) with External Rotation the lowest reliability. Glenohumeral and thoracohumeral elevation had the most consistent reliability. Scapular protraction/retraction had consistently poor reliability (ICC: 0-0.72; SEM: 3.5°-10.2°) with axial rotation also poor (ICC: 0.00-0.91; SEM: 6.3°-32.8°). This study determined inconsistent test-retest reliability of 3D-ULMA, using AM, to track dynamic performance of functional tasks in children with OBPP. It is the first study to outline measurement error in this population. This information permits more reliable interpretation of future studies of kinematic patterns in children with OBPP.

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.

Subscapularis Z-lengthening in children with brachial plexus birth palsy loses efficiency at mid-term follow-up: a retrospective cohort study

PURPOSE

The aim of this study was to evaluate early and mid-term clinical outcomes after isolated subscapularis Z-lengthening in children with shoulder internal rotation contractures resulting from brachial plexus birth palsy.

METHODS

Children with brachial plexus birth palsy treated with subscapularis tendon Z-lengthening from 2001 to 2011 were retrospectively reviewed. Over this period, 31 patients were identified. Primary outcome was improvement in Mallet score after surgery, and secondary outcome measures were active range of motion and Mallet sub-scores. Clinical outcomes were collected at three time intervals: pre-operatively, one-year post-operative and at latest follow-up.

RESULTS

After exclusion, 21 patients remained for further analysis. Mean age at surgery was 3.7 years (range, 1.2-8.7), and mean follow-up length was 6.5 years (2.9-9.7). Moderate improvements were found for mean Mallet score, active external rotation, active abduction and hand-to-mouth movement at one year and latest follow-up. However, improvements in active external rotation and Mallet score were not fully maintained at final follow up.

CONCLUSION

Isolated subscapularis Z-lengthening is effective at early follow-up, but results are not maintained at mid-term follow-up.

Proximal subscapularis release for the treatment of adduction-internal rotation shoulder contracture in obstetric brachial plexus palsy

INTRODUCTION

The purpose of this paper was to evaluate the results on shoulder function following isolated proximal subscapularis release in children with Erb's palsy.

METHODS

A retrospective study was conducted on 64 consecutive children with Erb's palsy who underwent a Carlioz proximal subscapularis release between 2001 and 2012. Fifty children with complete records and a minimum follow-up of 2 years were included for evaluation. Age at surgery ranged from 1.3 to 4.5 years (average 2.6 years). Preoperative active shoulder abduction/anterior elevation, active external and internal rotations as well as the Mallet score were compared with those found at 6 and 24 months postoperatively using the Student paired t test, with a confidence interval of 95 %. The results were compared between children <3 years of age at surgery and those older, and between children who had an isolated C5-C6 and those with greater involvement. p < 0.05 was considered statistically significant.

RESULTS

Active abduction improved 21° at 6 months and 31° (total) at 2 years (p < 0.01) with an overall Mallet abduction score improvement of 0.58 at 6 months and 0.6 (overall) at 2 years (p < 0.01). Active external rotation improved 52° at 6 months and 35° (total) at 2 years (p < 0.01) with an overall Mallet external rotation score improvement of 1.3 at 6 months (p < 0.01) and 0.52 (overall) at 2 years (p = 0.013). There was no statistically significant change in internal rotation (p = 0.37). We found no correlation between the child's age or the severity of involvement at surgery and the end result.

CONCLUSION

Proximal subscapularis release according to Carlioz is simple and effective in improving overall shoulder function in children with obstetric brachial plexus palsy, mainly abduction and external rotation. Improvement tends to reach a plateau around 6-12 months postoperatively.

Biomechanical Basis of Shoulder Osseous Deformity and Contracture in a Rat Model of Brachial Plexus Birth Palsy

BACKGROUND

The purpose of this study was to investigate the relative contributions of two proposed mechanisms, strength imbalance and impaired longitudinal muscle growth, to osseous and postural deformity in a rat model of brachial plexus birth palsy (BPBP).

METHODS

Thirty-two Sprague-Dawley rat pups were divided into four groups on the basis of surgical interventions to induce a strength imbalance, impaired growth, both a strength imbalance and impaired growth (a combined mechanism), and a sham condition in the left forelimb. Maximum passive external shoulder rotation angle (ERmax) was measured bilaterally at four and eight weeks postoperatively. After the rats were killed at eight weeks, the glenohumeral geometry (on microcomputed tomography) and shoulder muscle architecture properties were measured bilaterally.

RESULTS

Bilateral muscle mass and optimal length differences were greatest in the impaired growth and combined mechanism groups, which also exhibited >15° lower ERmax (p < 0.05; four weeks postoperatively), 14° to 18° more glenoid declination (p < 0.10), and 0.76 to 0.94 mm more inferior humeral head translation (p < 0.10) on the affected side. Across all four groups, optimal muscle length was significantly correlated with at least one osseous deformity measure for six of fourteen muscle compartments crossing the shoulder on the affected side (p < 0.05). In the strength imbalance group, the glenoid was 5° more inclined and the humeral head was translated 7.5% more posteriorly on the affected side (p < 0.05).

CONCLUSIONS

Impaired longitudinal muscle growth and shoulder deformity were most pronounced in the impaired growth and combined mechanism groups, which underwent neurectomy. Strength imbalance was associated with osseous deformity to a lesser extent.

CLINICAL RELEVANCE

Treatments to alleviate shoulder deformity should address mechanical effects of both strength imbalance and impaired longitudinal muscle growth, with an emphasis on developing new treatments to promote growth in muscles affected by BPBP.

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.

Late reconstruction of brachial plexus birth palsy

Brachial plexus birth palsy (BPBP) presents to the physician on a clinical spectrum, and may substantially impair the child. Potential interventions to improve function for the child with BPBP include physical therapy, microsurgical nerve reconstruction and nerve transfers, soft-tissue balancing and reconstruction with musculotendinous transfers, and osteotomies. Some interventions, such as nerve reconstruction, are best performed in infancy; others, such as muscle transfers and osteotomies, are performed to treat manifestations of this condition that appear later in childhood. Although controversy continues to exist regarding the natural history and surgical management of these patients, recent literature has improved our understanding of surgical indications, anticipated outcomes, and potential complications. On the basis of current evidence, we present here the recommendations for surgical intervention in the upper extremity of children with BPBP, and encourage early referral to a brachial plexus specialist to establish care.

Anterior shoulder release and tendon transfer as 1-stage procedure for treatment of internal rotation contracture deformity in obstetric brachial plexus injuries

PURPOSE

Children who had internal rotation contracture deformities of the shoulder secondary to obstetric brachial plexus palsy were studied. The outcomes of anterior shoulder release and tendon transfer in 1-stage procedure were analyzed.

METHODS

Anterior shoulder release and tendon transfer in 2 separate incisions as 1 procedure were performed in 76 patients for improvement of shoulder function. Anterior shoulder release was performed through the deltopectoral incision, starting with the coracoid process that extended 5 cm caudally. Osteotomy of the coracoid process subperiosteally with retaining the pectoralis minor attached to the periosteum. Z-plasty of the subscapularis and resuturing of the pectoralis minor short head of biceps and coracobrachialis to their original position were performed in all cases. A separate second incision in the posterior axillary fold was carried out to perform rerouting of the latissimus dorsi and teres major tendons with a mean follow-up of 5.6 years (range, 1-7 years).

RESULTS

The average active external rotation with the arm at the side increased from -26 + 15 degrees preoperatively to 67 + 17 degrees postoperatively (average gain, 85 degrees). The average shoulder abduction increased from 46 + 22 degrees preoperatively to 130 + 32 degrees postoperatively (average gain, 75 degrees). Mallet score improved from 12.3 to 22.6.

CONCLUSIONS

Anterior shoulder release combined with latissimus dorsi and teres major rerouting significantly improved global shoulder function.

Computational sensitivity analysis to identify muscles that can mechanically contribute to shoulder deformity following brachial plexus birth palsy

PURPOSE

Two mechanisms, strength imbalance or impaired longitudinal muscle growth, potentially cause osseous and postural shoulder deformity in children with brachial plexus birth palsy. Our objective was to determine which muscles, via either deformity mechanism, were mechanically capable of producing forces that could promote shoulder deformity.

METHODS

In an upper limb computational musculoskeletal model, we simulated strength imbalance by allowing each muscle crossing the shoulder to produce 30% of its maximum force. To simulate impaired longitudinal muscle growth, the functional length of each muscle crossing the shoulder was reduced by 30%. We performed a sensitivity analysis to identify muscles that, through either simulated deformity mechanism, increased the posteriorly directed, compressive glenohumeral joint force consistent with osseous deformity or reduced the shoulder external rotation or abduction range of motion consistent with postural deformity.

RESULTS

Most of the increase in the posterior glenohumeral joint force by the strength imbalance mechanism was caused by the subscapularis, latissimus dorsi, and infraspinatus. Posterior glenohumeral joint force increased the most owing to impaired growth of the infraspinatus, subscapularis, and long head of biceps. Through the strength imbalance mechanism, the subscapularis, anterior deltoid, and pectoralis major muscles reduced external shoulder rotation by 28°, 17°, and 10°, respectively. Shoulder motion was reduced by 40° to 56° owing to impaired growth of the anterior deltoid, subscapularis, and long head of triceps.

CONCLUSIONS

The infraspinatus, subscapularis, latissimus dorsi, long head of biceps, anterior deltoid, pectoralis major, and long head of triceps were identified in this computational study as being the most capable of producing shoulder forces that may contribute to shoulder deformity following brachial plexus birth palsy.

CLINICAL RELEVANCE

The muscles mechanically capable of producing deforming shoulder forces should be the focus of experimental studies investigating the musculoskeletal consequences of brachial plexus birth palsy and are potentially critical targets for treating shoulder deformity.

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.

Meta-analysis of function after secondary shoulder surgery in neonatal brachial plexus palsy

BACKGROUND

Shoulder internal rotation contracture, active abduction, and external rotation deficits are common secondary problems in neonatal brachial plexus palsy (NBPP). Soft tissue shoulder operations are often utilized for treatment. The objective was to conduct a meta-analysis and systematic review analyzing the clinical outcomes of NBPP treated with a secondary soft-tissue shoulder operation.

METHODS

A literature search identified studies of NBPP treated with a soft-tissue shoulder operation. A meta-analysis evaluated success rates for the aggregate Mallet score (≥ 4 point increase), global abduction score (≥ 1 point increase), and external rotation score (≥ 1 point increase) using the Mallet scale. Subgroup analysis was performed to assess these success rates when the author chose arthroscopic release technique versus open release technique with or without tendon transfer.

RESULTS

Data from 17 studies and 405 patients were pooled for meta-analysis. The success rate for the global abduction score was significantly higher for the open technique (67.4%) relative to the arthroscopic technique (27.7%, P<0.0001). The success rates for the global abduction score were significantly different among sexes (P=0.01). The success rate for external rotation was not significantly different between the open (71.4%) and arthroscopic techniques (74.1%, P=0.86). No other variable was found to have significant impact on the external rotation outcomes. The success rate for the aggregate Mallet score was 57.9% for the open technique, a nonsignificant increase relative to the arthroscopic technique (53.5%, P=0.63). Data suggest a correlation between increasing age at the time of surgery and a decreasing likelihood of success with regards to aggregate Mallet with an odds ratio of 0.98 (P=0.04).

CONCLUSIONS

Overall, the secondary soft-tissue shoulder operation is an effective treatment for improving shoulder function in NBPP in appropriately selected patients. The open technique had significantly higher success rates in improving global abduction. There were no significant differences in the success rates for improvement in the external rotation or aggregate Mallet score among these surgical techniques.

Subscapularis slide correction of the shoulder internal rotation contracture after brachial plexus birth injury: technique and outcomes

Internal rotation contracture is the most common shoulder deformity in patients with brachial plexus birth injury. The purpose of this investigation is to describe the indications, technique, and results of the subscapularis slide procedure. The technique involves the release of the subscapularis muscle origin off the scapula, with preservation of anterior shoulder structures. A standard postoperative protocol is used in all patients and includes a modified shoulder spica with the shoulder held in 60 degrees of external rotation and 30 degrees of abduction, aggressive occupational and physical therapy, and subsequent shoulder manipulation under anesthesia with botulinum toxin injections as needed. Seventy-one patients at 2 institutions treated with subscapularis slide between 1997 and 2010, with minimum follow-up of 39.2 months, were identified. Patients were divided into 5 groups based on the index procedure performed: subscapularis slide alone (group 1); subscapularis slide with a simultaneous microsurgical reconstruction (group 2); primary microsurgical brachial plexus reconstruction followed later by a subscapularis slide (group 3); primary microsurgical brachial plexus reconstruction followed later by a subscapularis slide combined with tendon transfers for shoulder external rotation (group 4); and subscapularis slide with simultaneous tendon transfers, with no prior brachial plexus surgery (group 5). Full passive external rotation equivalent to the contralateral side was achieved in the operating room in all cases. No cases resulted in anterior instability or internal rotation deficit. Internal rotation contracture of the shoulder after brachial plexus birth injury can be effectively managed with the technique of subscapularis slide.

Tendon transfer for treatment of internal rotation contracture of the shoulder in brachial plexus birth palsy

We retrospectively analyzed 63 patients with internal rotation contracture of the shoulder secondary to brachial plexus birth palsy treated with subscapularis sliding combined with either latissimus dorsi transfer (group A: n = 18) or latissimus dorsi and teres major transfer (group B: n = 45) to the rotator cuff. The mean age at time of surgery was 43 months (SD 21 months; range 8 months to 9 years). We used a modification of the Gilbert shoulder grading system for assessment. All patients showed statistically significant improvement of active shoulder abduction and external rotation without significant differences between the two groups. Significant external rotation contracture of the shoulder (inability to touch the abdomen with the wrist extended) occurred in 42 of 63 patients, and there was a greater incidence of external rotation contracture in group B. We conclude that surgery should be restricted to latissimus dorsi transfer without teres major transfer to avoid external rotation contractures. Our modification of the Gilbert grading system appears to be valid and applicable.

Arthroscopic release for shoulder internal rotation contracture secondary to brachial plexus birth palsy: clinical and magnetic resonance imaging results on glenohumeral dysplasia

Internal rotation contracture of the shoulder in brachial plexus birth palsy frequently leads to shoulder dysplasia. Six children underwent anterior arthroscopic release sparing the subscapularis. Clinical examination and MRI were performed preoperatively and repeated at the 5-year follow-up. MRI was carried out for assessment of glenohumeral dysplasia. Passive external rotation was improved by 63.3° without any limitation of active internal rotation. Active antepulsion/abduction was improved by 90°. Remodeling of the glenoid and improved coverage of the humeral head were observed in all cases. Shoulder arthroscopic release sparing the subscapularis seems to be an efficient procedure to restore external rotation without affecting active internal rotation.

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.

Brachial plexus birth palsy shoulder deformity treatment using subscapularis release combined to tendons transfer

INTRODUCTION

One possible sequela of obstetric brachial plexus palsy (OP) is impaired external rotation (ER) of the shoulder which, in addition to its functional consequences, can generate a posterior humeral head subluxation or dislocation. The goal of the present study was to assess medium-term clinical and radiological results of release of the subscapularis muscle with transfer of the latissimus dorsi and teres major muscles.

PATIENTS AND METHODS

From 1985 to 1995, a continuous series of 32 OP patients underwent subscapularis muscle release, associated in 24 cases to muscle transfer. Mean age was 2.5 years (range, 1-9.2 years). Shoulder function was assessed by measurement of passive ER and graded according to the modified Mallet classification at 1, 5 and 10 years' follow-up or before revision. The evolution of the glenohumeral deformity was assessed on CT images of glenoid retroversion and the humeral head subluxation (% of humeral head covered), before and 5 years after surgery.

RESULTS

Mean postoperative follow-up was 9.5+/-5.6 years. Treatment brought significant improvement in passive ER (mean preoperative and 1-year follow-up values: -10 degrees and 52 degrees, respectively). This explained the good modified Mallet score at 1 year: mean=18.4/25. Subsequent significant progressive degradation was noted: 10 years postoperatively, mean ER amplitude and modified Mallet score were respectively 13 degrees and 15.8. The CT study showed correction of the glenoid retroversion (mean preoperative and 5-year follow-up values: 29 degrees and 18 degrees, respectively), and of the humeral head subluxation (mean preoperative and 5-year follow-up values: 25 and 39%, respectively). Surgical revision was indicated six times (five patients): two latissimus dorsi and teres major transfers (not performed initially) and four derotational humeral osteotomies. Three-quarters of the patients who did not initially have muscle transfer had to be reoperated or else showed ER insufficiency at last follow-up.

DISCUSSION AND CONCLUSION

Surgical treatment produces objective functional gain, even if this diminishes over time. Moreover, it prevents or corrects posterior subluxation of the shoulder. It is indicated when passive ER amplitude is negative. It seems advisable to associate release to muscle transfer.

LEVEL OF EVIDENCE

Level IV Retrospective study.

Structural changes in muscle and glenohumeral joint deformity in neonatal brachial plexus palsy

BACKGROUND

Internal rotation contracture of the shoulder is common in children with neonatal brachial plexus palsy. A long-standing contracture may cause osseous deformities in the developing shoulder. The purpose of the study was to evaluate the relationship between osseous deformities of the glenohumeral joint and structural differences due to muscle denervation in the rotator cuff muscles.

METHODS

One hundred and two children with residual neonatal brachial plexus palsy underwent magnetic resonance imaging of both shoulders. The glenoid version and posterior, medial, and superior subluxation of the humeral head were measured. The shapes of the glenoid and the humeral head were categorized, and the infraspinatus, supraspinatus, subscapularis, and deltoid muscles were scored as being normal, atrophic, or atrophic with fatty degeneration.

RESULTS

Muscle degeneration was most prominent in the subscapularis muscle. Glenoid version correlated with the structural differences in the subscapularis muscle. Posterior subluxation of the humeral head and the shape of the glenoid correlated with all abnormal rotator cuff muscles. Superior humeral subluxation correlated only with changes in the supraspinatus muscle. Medialization and the shape of the humeral head were not associated with atrophic changes of the rotator cuff. Regeneration of the rotator cuff muscles was not significantly different in patients with a C5-C6 (C7) or a complete brachial plexus lesion. However, the changes in glenoid version, the degree of posterior humeral subluxation, and the degree of medial humeral subluxation were significantly more severe in patients with a C5-C6 (C7) lesion compared with those in patients with a complete lesion of the brachial plexus.

CONCLUSIONS

Structural differences in the rotator cuff muscles alter the direction of the humeral head forces on the developing glenoid fossa and can lead to osseous deformities. Glenohumeral deformities are significantly greater with a C5-C6 (C7) lesion than with a complete brachial plexus lesion in which the large internal rotators are also affected. Reducing the muscular imbalance that occurs with a C5-C6 (C7) lesion could diminish glenohumeral joint incongruency and may improve the outcome of subsequent soft-tissue release or tendon transfer surgery.

Current concepts in the management of brachial plexus birth palsy

Brachial plexus birth palsy, although rare, may result in substantial and chronic impairment. Physiotherapy, microsurgical nerve reconstruction, secondary joint corrections, and muscle transpositions are employed to help the child maximize function in the affected upper extremity. Many present controversies regarding natural history, microsurgical treatment, and secondary shoulder reconstructive surgery remain unresolved in infants with brachial plexus birth palsies. Recent literature has enhanced our understanding of the pathoanatomy and natural history of the injury as well as the surgical indications, expected outcomes, and complications; this literature has led to improved care of these patients. Based on the present evidence, recommendations for both microsurgery and shoulder reconstruction with tendon transfer and arthroscopic and open reductions are presented.

Arthroscopic treatment of internal rotation contracture and glenohumeral dysplasia in children with brachial plexus birth palsy

BACKGROUND

The purpose of the study was to assess the ability of arthroscopic anterior release, +/- tendon transfers to maintain shoulder joint alignment in children with brachial plexus palsy, and to assess their outcome after arthroscopic reduction.

METHODS

Forty-four patients underwent arthroscopic release, +/- tendon transfers to realign a dysplastic glenohumeral joint in children with brachial plexus palsy. Twenty-eight children underwent isolated release and 16 children underwent concomitant tendon transfers. MRI and clinical measurements were used to assess outcome at 1-year follow-up.

RESULTS

There was a significant improvement (P < .001) in both retroversion from -34 (+/-15) to -19 (+/-13), and percentage of the humeral head anterior to the middle of the glenoid fossa (PHHA) from 19% (+/-12%) to 33% (+/-12%), at 1 year. Passive external rotation increased from -26 (+/-20) degrees to 47 (+/-17) degrees (P < .001). Active elevation increased from 112 (+/-28) degrees to 130 (+/-38) (P = .008) degrees. Patients that underwent tendon transfers obtained greater active elevation, 147 (+/-9) degrees compared to 119 (+/-6) degrees. Mallet aggregate and domain scores also demonstrated statistically significant improvements.

CONCLUSIONS

Our results after arthroscopic release +/- tendon transfers are encouraging with improvements in joint alignment and clinical evaluations following surgery. The clinical improvements paralleled the MRI corrections. Importantly, superior outcomes were associated with better preoperative clinical and MRI status. This indicates that early recognition of glenohumeral dysplasia and timely intervention results in better shoulder motion and improved joint alignment.

LEVEL OF EVIDENCE

4.

Correlation of radiographic muscle cross-sectional area with glenohumeral deformity in children with brachial plexus birth palsy

BACKGROUND

Muscle imbalance about the shoulder in children with persistent brachial plexus birth palsy is thought to contribute to glenohumeral joint deformity. We quantified cross-sectional areas of the internal and external rotator muscles in the shoulder by magnetic resonance imaging in patients with chronic brachial plexopathy and the correlation between these muscle cross-sectional area ratios and glenohumeral deformity. The purposes of this investigation were to evaluate differences in the ratios between affected and unaffected shoulders in the same individual and to assess whether an increased internal to external rotator muscle cross-sectional area correlated with greater glenohumeral deformity.

METHODS

This cohort study consisted of magnetic resonance imaging of seventy-four patients with chronic neuropathic changes about the shoulder from brachial plexus birth palsy. There were at least nine patients with scans available for each of the five classified subtypes of glenohumeral deformity: type I (fifteen patients), type II (seventeen), type III (seventeen), type IV (sixteen), and type V (nine). Cross-sectional areas of the pectoralis major, teres minor-infraspinatus (external rotators), and subscapularis muscles were measured. The supraspinatus muscle cross-sectional area could not be reliably measured. The ratio of subscapularis to external rotators, the ratio of pectoralis major to external rotators, and the compound ratio of subscapularis and pectoralis major to external rotators were compared with the severity of the glenohumeral deformity. Passive range of motion, Mallet and Toronto clinical scores, and Narakas type were also compared with the severity of the glenohumeral deformity and the muscle cross-sectional area measurements.

RESULTS

Muscle cross-sectional area ratios were significantly correlated with glenohumeral deformity type. The mean ratio of pectoralis major to external rotators for affected shoulders over all deformity types compared with that for unaffected shoulders was significantly increased by 30% (p < 0.001); the mean ratio for subscapularis and pectoralis major to external rotators, by 19% (p = 0.015), and the mean ratio for subscapularis to external rotators, by 10% (p = 0.008). There was a significant increase in the ratio of pectoralis major to external rotators in affected shoulders within each type of deformity. Analysis of variance indicated higher ratios of pectoralis major to external rotator muscle cross-sectional areas in more severe deformity types (p < 0.001). There were significant differences in external rotation measurements with the shoulder at 90 degrees of abduction only among glenohumeral deformity types I, II, and III (p < 0.05).

CONCLUSIONS

The degree of muscle imbalance between internal and external rotators about the shoulder is measurable by magnetic resonance imaging in children with persistent brachial plexopathy, and the imbalance correlates with the degree of glenohumeral deformity. Our results may provide useful information to guide the timing and the choice of operative intervention in these children.

Nerve reconstruction in patients with obstetric brachial plexus injury results in worsening of glenohumeral deformity: a case-control study of 75 patients

Whereas a general trend in the management of obstetric brachial plexus injuries has been nerve reconstruction in patients without spontaneous recovery of biceps function by three to six months of age, many recent studies suggest this may be unnecessary. In this study, the severity of glenohumeral dysplasia and shoulder function and strength in two groups of matched patients with a C5-6 lesion at a mean age of seven years (2.7 to 13.3) were investigated. One group (23 patients) underwent nerve reconstruction and secondary operations, and the other (52 patients) underwent only secondary operations for similar initial clinical presentations. In the patients with nerve reconstruction shoulder function did not improve and they developed more severe shoulder deformities (posterior subluxation, glenoid version and scapular elevation) and required a mean of 2.4 times as many operations as patients without nerve reconstruction. This study suggests that less invasive management, addressing the muscle and bone complications, is a more effective approach. Nerve reconstruction should be reserved for those less common cases where the C5 and C6 nerve roots will not recover.

Computed tomography of the shoulders in patients with obstetric brachial plexus injuries: a retrospective study

Background

Scapular hypoplasia, elevation, and rotation (SHEAR) deformity and posterior subluxation of the humeral head are common tertiary sequelae of obstetric brachial plexus injuries (OBPI). Interpretations of images from bilateral computed tomography (CT) scans of the upper extremities are critical to the diagnosis and treatment plan for patients with these bony deformities resulting from OBPI.

Methods

We conducted a retrospective study to investigate the accuracy of radiologic reports in the diagnosis of SHEAR or posterior subluxation of the humeral head in OBPI patients. CT studies from 43 consecutive patients over a 33-month period were used in the study. For each patient, we compared the results from the radiologic report to those from a clinical examination given by the attending surgeon and to measurements taken from the CT studies by biomedical researchers.

Results

A comparison of SHEAR measured from the 3-D CT images to the diagnoses from the radiologists, revealed that only 40% of the radiological reports were accurate. However, there was a direct correlation between the use of the 3-D CT images and an accurate SHEAR diagnosis by the radiologists (p < 0.0001). When posterior subluxation was measured in the affected and contralateral shoulders, 93% of the patients that had greater than a 10% difference between the two shoulders did not have their deformity diagnosed. The radiological reports diagnosed 17% of these patients with a 'normal' shoulder. Only 5% of the reports were complete, accurately diagnosing SHEAR in addition to posterior subluxation.

Conclusion

Due to the low incidence rate of OBPI, many radiologists may be unfamiliar with the sequelae of these injuries. It is therefore critical that radiologists are made aware of the importance of an accurate measurement and diagnosis of the SHEAR deformity. Due to their lack of completeness, the radiological reports in this study did not significantly contribute to the clinical care of the patients. In order for OBPI patients to receive the highest standard of care, the final diagnosis from their radiological imaging should be deferred to a brachial plexus specialist who is experienced with these types of injuries.