The effect of infraspinatus hypotrophy and weakness on the arthroscopic treatment of spinoglenoid notch cyst associated with superior labrum anterior-to-posterior lesions

Purpose

Patients with spinoglenoid notch cyst associated with superior labrum anterior-to-posterior (SLAP) lesions were evaluated. The patients were all treated by arthroscopic cyst decompression combined with SLAP repair. The hypothesis of the study was that the patients who underwent prolonged conservative treatment period prior to surgery would exhibit significant infraspinatus hypotrophy and weakness, and their postoperative clinical and functional outcomes would be less satisfactory.

Methods

Sixteen patients exhibited positive MRI and EMG findings with clinical signs of weakness and pain. The median age was 40.5 years (range 32–52), and the study group consisted of 11 males and 5 females with a median follow-up period of 26 months (12–48). The median duration of symptoms and conservative treatment prior to the surgical intervention was 3.5 months (1–14). Seven patients in group A exhibited infraspinatus hypotrophy. Group B comprised 9 patients without infraspinatus hypotrophy.

Results

The results of the pre- and postoperative Constant scores, visual analogue scale (VAS) scores, and external rotation strength test rates were compared between groups. They all improved in terms of pain, strength, and function (P < 0.05). Significant differences were observed between the pre- and postoperative external rotation strengths and Constant scores (P < 0.05). However, no significant difference was observed between the pre- and postoperative VAS scores (n.s.). A significant correlation was observed in group A between surgical timing, the preoperative external rotation strength ratio (P = 0.04) and the postoperative VAS scores (P = 0.013).

Conclusion

The arthroscopic treatment was satisfactory with good clinical outcomes. Infraspinatus hypotrophy occurred in cases of prolonged surgical duration and significantly affected external rotation strength and functional outcomes.

Level of evidence

Retrospective comparative study, Level III.