Subscapularis sparing approach vs. tenotomy of the subscapularis tendon in reverse shoulder arthroplasty: a prospective, randomized, double-blinded clinical trial.

PURPOSE: The management of the subscapularis tendon in reverse shoulder arthroplasty (RSA) is still discussed controversially. We hypothesized, that (1) patients treated with the subscapularis sparing approach would present with a higher internal rotational strength, while (2) the external rotational motion is not reduced.

METHODS

A prospective, randomized, double blinded clinical trial was conducted. Patients were randomized into two groups: subscapularis sparing approach (group 1) or tenotomy without repair of the subscapularis tendon (group 2). Clinical follow-up examinations were performed at 12 and 24 months. Primary outcome measure was the internal rotational strength at two years measured by a bear-hug test. Secondary outcome measure was the degree of external rotation. The clinical outcome was measured and compared based on the Constant Score (CS), patient satisfaction and Subjective Shoulder Value (SSV).

RESULTS

Thirty-four patients with a mean age of 74 years were included, 17 for each group. Indication for surgery was osteoarthritis (6-times), non-reconstructable rotator cuff tear (5-times), and defect arthropathy (23-times). Internal rotational strength was higher in group 1 than in group 2 (bear-hug: 51 Nm vs. 39 Nm). With the contralateral side defining the reference, there was a significant higher loss of for internal rotational strength in group 2 than in group 1 (30 Nm vs. 8.2 Nm; p = 0.006). External rotation did not differ between the groups. The CS improved significantly throughout surgery (p < 0.001). No clinical difference between the groups was observed at 24 months follow-up regarding the CS (p = 0.984). However, subgroup analysis showed better internal rotation preserving the subscapularis.

CONCLUSION

Although technical even more demanding, the subscapularis sparing approach represents advancement in shoulder surgery. By preserving the subscapularis tendon, this technique enhances muscle function with higher internal rotational strength and motion without deficits in external rotation.

LEVEL OF EVIDENCE: I.