Isolated Ruptures of the Infraspinatus: Clinical Characteristics and Outcomes

Background: Isolated infraspinatus tear is very rare and clinical features are not as well known, therefore the purpose of this study was to evaluate clinical characteristics and outcomes of isolated infraspinatus tear that authors experienced. Methods: Authors reviewed 288 cases of full-thickness rotator cuff tear involving infraspinatus between 2010 and 2015, and retrospectively analyzed six cases of isolated infraspinatus tear. Perioperative clinical characteristics, postoperative functional outcomes of 6 months were investigated. Functional evaluation included visual analogue scale (VAS), range of motions, American Shoulder and Elbow Surgeons (ASES) score, and Constant score. Results: Calcific tendinitis was accompanied in 4 cases (66.7%). Three of them received steroid injection or aspiration or extracorporeal shockwave therapy. Mean preoperative pain VAS was 7.1 (range, 5-9), and mean postoperative pain VAS at 6 months later was 1.6 (range, 0-5). Preoperative muscle strength by isokinetic muscle performance test showed 52% deficit of abduction and 37.6% deficit of external rotation. All 6 patients had arthroscopic repair of the infraspinatus tendon. All the patients at the 6 months follow-up exhibited clinical improvement in the Constant score (67.8 [range, 45-77] to 89.3 [range, 81-100], p=0.029), and ASES score (52.3 [range, 30-77] to 90.0 [range, 80-100], p=0.002). There was no healing failure on imaging. Conclusions: Isolated infraspinatus tendon tear was frequently accompanied by calcific tendinitis, but pathophysiologic relationship should need more study. To rule out neurogenic etiology, magnetic resonance imaging and electromyography would be helpful. Arthroscopic infraspinatus tendon repair and supraspinatus debridement showed relatively good result in painful shoulder.