Correction of the CSA does not decrease the re-tear rate after SSP repair

Background The re-tear rate after supraspinatus tendon (SSP) repair is high despite optimization of surgical techniques. The critical shoulder angle (CSA) > 35° has been identified as a risk for re-tear. Surgical reduction of the CSA performing additional lateral acromioplasty (ALAP) is intended to reduce the risk. Objective We aimed to evaluate the effect of ALAP on the re-tear rate in patients with a CSA > 35° after SSP repair. Patients and methods The study included 49 shoulders fulfilling predefined inclusion criteria. The patients were assigned to two groups; group I (25 SSP) was additionally treated with an ALAP. In group II (24 SSP) standard acromioplasty was performed during reconstruction. Magnetic resonance imaging and a clinical examination (Constant Score; CS) were performed 12 months after surgery. Results After 15 months group I showed a re-tear rate of 20%, a decreased CSA (mean 38.0° preoperatively vs. 34.5° postoperatively) and an increase in CS (mean 53.9 vs. 84.6). After 16 months group II showed a re-tear rate of 16.7%, no difference between pre- and postoperative CSA (37.8° vs. 37.6°), and an increase in CS (48.9 vs. 84.5). There was no difference between the groups in terms of re-tears and postoperative CS (p = 0.4557), but there was a significant difference in postoperative CSA (p 35° did not have a worse clinical outcome and no increased rate of re-tears compared with patients with a mechanically reduced CSA. Conclusion Additive lateral acromioplasty does not decrease the re-tear rate after arthroscopic SSP repair. However, ALAP significantly decreases the CSA to normal values.