A common residual of brachial plexus birth palsy is internal rotation contracture at the glenohumeral joint. A number of intraarticular and exraarticular procedures have been developed and attempted to improve shoulder range of motion with no concensus on the best option. This study addresses isolated subscapularis muscle lengthening for treatment of this problem. The cohort is small. Eighteen children were treated over a five-year span and five were excluded due to insufficient preoperative measurements. The surgical indications included persistent internal rotation contracture defined as passive lateral rotation at midline less than 35 degrees. Other indications included active lateral rotation at 90 degrees of less than 20 degrees. All patients failed intensive physical therapy.
The procedure consisted of an open deltopectoral incision with step-cut lengthening of the subscapularis. The authors indicate a “peak” into the joint through a transverse osteotomy made at the level of the rotator interval. Varying degrees of glenohumeral dysplasia were noted. Postoperatively, the children were placed in external rotation in abduction. The cast was removed six-weeks after surgery and physical therapy was instituted. Results confirm previous studies about films. These radiographs were found to be unreliable in predicting the degree of glenohumeral dysplasia. Shoulder range of motion improved fairly impressively. Abduction increased an average of 30 degrees, flexion an average of 47 degrees, lateral rotation at 90 degrees an average of 49 degrees, lateral rotation at midline an average of 26 degrees (passive). There was a slight loss of medial or internal rotation measuring about -20 degrees. Some patients did note problems reaching midline for dressing.
The positive results with isolated subscapularis lengthening in this study deserve comment. Rather than tendon transfer to augment external rotation, these authors attempted to lessen internal rotation through tendon lengthening. This resulted in better balance around the shoulder and improved range of motion, especially external rotation and abduction. Unfortunately, the authors failed to prove that isolated subscapularis lengthening is the appropriate procedure for all children regardless of the degree of glenohumeral dysplasia. Many of the children were older than five-years of age and most likely had considerable glenohumeral dysplasia. Most likely, subscapularis lengthening should be in the armamentarium of surgeons that treat shoulder impairment following brachial plexus birth palsy. Subscapularis lengthening can be performed via an open incision or arthroscopic technique. This specific procedure should be tailored to the age of the patient, degree of deformity, and amount of imbalance about the shoulder.
Shoulder, Brachial, Plexus, Palsy, Glenohumeral, Dysplasia, Subscapularis