Abstract
Background
Shoulder deformity and inadequate shoulder function in brachial plexus birth palsy (BPBP) occur due to imbalance between the shoulder abductors, external rotators, adductors and internal rotators. This is due to cross innervation of the regenerating axons and subsequent target muscle innervation. These lead to internal rotation deformity along with glenohumeral dysplasia. Conjoint muscle transfer in the form of latissimus dorsi and teres major muscle combined with release and slide of subscapularis muscle improves shoulder functions. This study aims to evaluate the outcomes of shoulder function after a simultaneous conjoint muscle transfer and subscapularis slide in the management of BPBP.
Methods
18 children with BPBP, who presented with shoulder deformity and inadequate shoulder functions, underwent conjoint muscle transfer along with subscapularis muscle slide. At 18 months, shoulder functions were assessed preoperatively and postoperatively using Mallet score system and range of motions. Statistical analysis was performed to ascertain if the outcomes were statistically significant.
Results
Mean age was 4.64 years with a mean preoperative Mallet score of 10.89 ± 1.60 and mean postoperative Mallet score of 16.22 ± 1.86. At 18 months, mean gain in shoulder abduction at 18 months was 57.22 ± 16.11° with external rotation of 26.66 ± 7.67°. All children showed improvement in shoulder functions. There was no correlation between the clinical outcomes and age of the child.
Conclusion
This procedure was effective in improving shoulder functions in a cohort of patients. The long-term effect of this procedure, however, remains to be evaluated by further follow-up and with similar such studies.
Keywords: Conjoint muscle transfer, Subscapularis slide, Brachial plexus birth palsy
Introduction
The incidence of brachial plexus birth palsy (BPBP) ranges from 0.5 to 2 per 1000 births and is more common in underdeveloped countries.1 Although a majority of them result in complete recovery, some may show partial and slow recovery. Literature suggests that the rate of complete and spontaneous recovery varies from 30% to 95%.2 Factors that are associated with BPBP include large birth weight, breech delivery and shoulder dystocia.3
Microsurgical reconstruction of BPBP is still an evolving field of reconstructive microsurgery and peripheral nerve surgery. Presently, there is no consensus among the clinicians regarding surgical indications and timing of surgery. Many still advice parents to adhere to physiotherapy programs despite children showing no signs of recovery after a reasonable period. Current evidence published in literature favours primary nerve surgery in patients who do not show signs of early recovery.4 Therefore, there appears to be a paradigm shift in the management of BPBP with the advice “wait for a year to see if recovery occurs” no longer seems appropriate.5 Incomplete spontaneous recovery results in secondary deformities in the shoulder often due to muscle imbalances and cross innervation from the regenerating axons.6 Current management focuses on altering these muscle imbalances using muscles such as latissimus dorsi and teres major. Release and transfer of these muscles to rotator cuff improve abduction and external rotation. Few studies mention subscapularis slide as an isolated procedure to improve shoulder function, whereas some other techniques describe simultaneous muscle transfers along with subscapularis slide.6, 8, 9 We believe that subscapularis slide when performed simultaneously with conjoint muscle transfer improves the outcomes in children with BPBP who present with compromised shoulder functions. The present study describes the outcomes of conjoint muscle transfer along with subscapularis slide in children with BPBP presenting with shoulder deformity and inadequate shoulder function.
Materials and methods
From January 2016 to June 2018, 20 children with BPBP who presented to the tertiary care centre were included in the study. Two children with irreducible posterior dislocation of the shoulder, which required skeletal interventions in the form of de-rotational humeral osteotomy were excluded from the study. Hence, 18 children became part of the study. Three children had already been operated previously with primary nerve surgery and had developed residual internal rotation deformity and restricted shoulder abduction. Preoperatively, the children were evaluated for active and passive range of shoulder abduction and external rotation. Modified Mallet score was used for the assessment of shoulder functions. It considers five parameters namely, global abduction, global external rotation, hand-to-neck movement, hand-to-spine movement and hand-to-mouth movement. Each parameter is graded from 1 to 5 with a maximum score of 25. A higher score indicates a better shoulder function. Other methods to assess shoulder functions include the Gilbert and the Birch system.10,11 However, the Mallet score is most commonly used as it provides a more detailed assessment of shoulder functions; Mallet score was calculated preoperatively and at the end of 18 months follow-up. Radiographs of the shoulder joint were studied to assess glenohumeral joint and its congruity.
Surgical technique
The surgery was aimed at soft tissue release with subscapularis slide, and in selected cases, pectoralis muscle releases to correct the internal rotation deformity along with conjoint latissimus dorsi and teres major muscle transfer to the rotator cuff. With the patient placed in a lateral decubitus position, an incision marked along the lateral border of scapula was curved superiorly along the posterior border of axilla toward the humeral attachment of the conjoint muscle. Another incision line was made at the inferior border of the spine of the scapula. The incision lines were infiltrated with 1:200,000 adrenaline saline solution for adequate haemostasis. The incisions were deepened until the anterior border of latissimus dorsi muscle was seen, which was retracted posteriorly. This exposed the lateral border and the inferior angle of the scapula. Latissimus dorsi–teres major conjoint muscle was identified and divided near humeral attachment. The scapula was then stabilised with three 2-0 Nylon sutures and the subscapularis muscle was dissected from the anterior surface of scapula using electrocautery and periosteal dissector in a subperiosteal plane as far proximally as possible. The humerus was externally rotated to confirm its adequate release. If the external rotation was still not completely achieved after dissection and slide of the subscapularis muscle, the pectoralis major was identified and if found taut was released through a 4 cm deltopectoral incision. Once the release was thought to be adequate, the conjoint muscle of latissimus dorsi and teres major which had been pre-dissected was rerouted through a subcutaneous tunnel and sutured to the infraspinatus muscle, which was dissected by an incision in the lateral part of the spine of the scapula with 2-0 Nylon. The arm was kept maximally abducted and externally rotated (Fig. 1). The wound was closed over a drain and shoulder immobilised with a shoulder spica keeping the shoulder in about 110° of abduction and complete external rotation. This spica was worn for 6 weeks and subsequently, a passive range of motion was initiated under supervision. Patients were asked to report for follow-up every 4 weeks for the first 3 months and subsequently, once every 3 months, and the range of movements along with Mallet scores were recorded (Fig. 2, Fig. 3).
Fig. 1.
Dissection and suturing of conjoint muscle to infraspinatus.
Fig. 2.
Preoperative and postoperative Mallet scores (upper and lower case alphabets represent preoperative and postoperative Mallet scores, respectively).
Fig. 3.
Improvement in shoulder abduction (A—preoperative, B—postoperative).
Statistical analysis
The data were entered using Mac Numbers (Apple Inc.) and analysed using SPSS statistical analysis software, version 20. As the data were not normally distributed (Kolmogorov–Smirnov test for normality), the Wilcoxon signed-rank test was used for statistical analysis in the preoperative and postoperative variables. P-value of <0.05 was taken as significant. Spearman Rho analysis was performed to test for correlation between the age and net gain in active shoulder abduction and external rotation measured in degrees and Mallet scores.
Results
The mean age of children was 4.64 years ± 2.17 SD. Eleven were male and seven were female. Thirteen had right-sided palsy and five had left-sided palsy.
All children showed improvement in postoperative total Mallet score at 18 months (preoperative mean 10.89 ± 1.60 SD to postoperative mean 16.22 ± 1.86 SD). The mean individual Mallet score also shows statistically significant improvement. Active shoulder abduction improved by 57.22° (preoperative mean 71.67° to postoperative mean 128.89°). The active external rotation improved by 20.56° (preoperative mean 6.11° to postoperative mean 20.56°). The results of the measured outcomes are summarised in Table 1. The Spearman Rho analysis was performed for the correlation between the age and the outcomes and was not found to be significant. The Rho value is shown in Table 2, and the correlation is shown in scatter plot (Fig. 4).
Table 1.
Preoperative and postoperative outcomes.
| Category | Mallet scores (mean ± SD) |
Active range of motion (mean ± SD) |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| Abduction | External rotation | Hand-to-neck | Hand-to-back | Hand-to-mouth | Total score | Abduction in degrees | External rotation in degrees | ||
| Preoperative | Mean | 2.56 ± 0.51 | 1.44 ± 0.62 | 2.00 | 2.44 ± 0.78 | 2.44 ± 0.62 | 10.89 ± 1.60 | 71.67 ± 28.90 | −6.11 ± 7.88 |
| Median | 3 | 1 | 2 | 2.5 | 2 | 11 | 67.5 | −5 | |
| Postoperative | Mean | 3.56 ± 0.86 | 2.78 ± 0.65 | 3.11 ± 0.68 | 3.33 ± 0.84 | 3.44 ± 0.51 | 16.22 ± 1.86 | 128.89 ± 22.00 | 20.56 ± 6.84 |
| Median | 4.00 | 3.00 | 3.00 | 3.50 | 3.00 | 16.00 | 125.00 | 20.00 | |
| Z value | −3.0954 | −3.7236 | −3.5162 | −3.4078 | −3.4078 | −3.7236 | −3.7236 | −3.7236 | |
| P value | <0.05 | <0.05 | <0.05 | <0.05 | <0.05 | <0.05 | <0.05 | <0.05 | |
Table 2.
Age correlation between the outcomes.
| S. no. | Age | Increase in Mallet score | Gain in abduction | Gain in external rotation |
|---|---|---|---|---|
| 1 | 60 | 5 | 60 | 30 |
| 2 | 96 | 7 | 100 | 25 |
| 3 | 132 | 6 | 80 | 15 |
| 4 | 48 | 5 | 30 | 40 |
| 5 | 36 | 6 | 55 | 15 |
| 6 | 72 | 5 | 55 | 30 |
| 7 | 30 | 6 | 55 | 30 |
| 8 | 48 | 4 | 50 | 30 |
| 9 | 36 | 4 | 65 | 20 |
| 10 | 36 | 8 | 50 | 30 |
| 11 | 84 | 5 | 55 | 35 |
| 12 | 48 | 4 | 30 | 15 |
| 13 | 60 | 4 | 50 | 25 |
| 14 | 36 | 4 | 55 | 20 |
| 15 | 48 | 4 | 55 | 30 |
| 16 | 48 | 6 | 75 | 25 |
| 17 | 36 | 8 | 55 | 40 |
| 18 | 48 | 5 | 55 | 25 |
| rs value | −0.06002 | 0.27556 | −0.01256 | |
| P value | 0.81298 | 0.26839. | 0.96055 | |
| Not significant | Not significant | Not significant |
Fig. 4.
Scatter plot showing the correlation of age and outcomes.
Discussion
Shoulder deformities in children with BPBP result in severe functional loss and deformities of the glenohumeral joint due to internal rotation and adduction contractures. This is because of cross innervation of regenerating axons and powerful action of internal rotators and adductors of shoulder as compared to weak external rotators and abductors. Despite improved outcomes of primary nerve surgery, the late presentation of children beyond the period where primary nerve surgery is not feasible is common. In our study, only three patients had undergone primary nerve surgery and the remaining 15 patients were presented beyond the period of primary nerve surgery. This could be attributed to an inadequate understanding of the physiology of BPBP among the primary care physicians. The current strategy for improving the shoulder functions in late BPBP includes muscle transfers, soft tissue and muscle release, Botulinum toxin A injection as well as humeral and glenoid osteotomies. Presently, there are no guidelines for selecting the procedures as a set protocol and in most cases, the treatment is individualised.
The most common deformity is internal and adduction contracture limiting the external rotation and shoulder abduction.12,13 The subscapularis slide, along with soft tissue release, pectoralis major release/lengthening and conjoint muscle transfers have been described for improving the function, which results in improvement in Mallet scores.
In this study, the mean total Mallet score improved from 10.89 to 16.22, which was statistically significant. Statistically, significant improvement was also seen in the shoulder abduction and external rotation when measured in degrees. The results are similar to other published studies, which have also reported an improvement in the total Mallet scores, shoulder abduction and external rotation.14 Sibinski et al, who evaluated the Mallet scores in 24 children, showed improvement from a mean of 12.3 preoperative to 17.4 postoperative score.15 Cohen et al reported an improvement in shoulder abduction from 113° to 128° with subscapularis release along with latissimus dorsi and teres major muscle transfer to rotator cuff.16 The surgical release of subscapularis and pectoralis major muscle versus injection of Botulinum toxin A has been a matter of debate and many authors reporting good results with Botulinum toxin A injection in the subscapularis and pectoralis major muscle. In a study of 150 cases of late obstetric brachial plexus palsy, Thatte et al reported improvement in all parameters of shoulder function including shoulder abduction, external rotation and aggregated Mallet scores.17 In addition to muscle transfers, they had used Botulinum toxin A injection into the subscapularis and pectoralis major. Considering the need for repeated injections, a high cost we prefer subscapularis slide and release of pectoralis major in selected cases with good results. This irreversible surgical procedure along with the transfer of powerful internal rotators for abduction and external rotation did not affect the postoperative internal rotation.
Timing of surgery in patients who present with shoulder deformities still remains debatable as varying series by the authors have stated a mean age of surgery is in the range between 1 and 17 years.18, 19, 20 The mean age in this study was 4.64 years (range 2.5–11 years). We also studied the correlation between age and the outcomes. The Spearman Rho analysis did not show any correlation between age and the functional outcomes namely active external rotation, active shoulder abduction as measured in degree and Mallet scores (rs 0.27556, P = 0.26839; rs −0.01256, P = 0.96055 and rs −0.06002, P = 0.81298, respectively). These findings are different from the other published studies in which the age, preoperative shoulder abduction and triceps muscle power were helpful in predicting postoperative shoulder abduction.11 This could be due to a higher range of age from 1.4 years to 17 years that could have influenced the outcomes. In our study, patient’s age ranged between 2.5 and 11 years in which period, bony changes in the glenohumeral joint have not occurred.
The study has limitations primarily of small sample size. Owing to limited clientele and uncommon condition of presentation, this study was possible over a period of 3 years, but it does show improvement in shoulder functions with children carrying out activities like playing with their peers and taking part in school activities. Another drawback of this study is a short period of follow-up (18 months), and hence long-term results could not be commented on. In this study, the subscapularis slide and conjoint latissimus dorsi and teres major muscle transfer improved shoulder abduction and external rotation along with aggregate Mallet scores. We recommend these procedures in children with BPBP presenting with shoulder deformity and poor shoulder functions.
Disclosure of competing interest
The authors have none to declare.
Acknowledgements
Authors acknowledge Dr Seema Patrikar, Dept. of Community Medicine, AFMC, for guiding them in Statistical analysis.
References
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