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

Abstract

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.