Minimally Invasive Subscapularis Release: A Novel Technique and Results

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.

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.

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.

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.

Level III-retrospective comparative study.