Partial Tears of the Subscapularis Tendon Found During Arthroscopic Procedures on the Shoulder

Background: Prevalence and clinical significance of partial tears of the subscapularis tendon have not been widely studied. Purpose: To determine prevalence of and clinical factors associated with partial tears of the subscapularis tendon at arthroscopy. Study Design: Case control study. Methods: During arthroscopic procedures on 314 consecutive shoulders, the arthroscopically visible portion of the subscapularis tendon was probed. Patients with and without partial tears were compared for prospectively identified variables. Results: Partial tears were found in 60 of the 314 patients (19%). Increasing age and dominant arm involvement were significant variables for partial tears. Significantly associated factors included supraspinatus tendon tears (54 of 60; 90%), rotator cuff disease (44 of 60, 73%), and posterosuperior labral fraying (34 of 47, 72%). Increasing age, dominant arm involvement, and coexisting infraspinatus tendon tears were strong independent risk factors for partial tears. Conclusion: Partial tears of the subscapularis tendon are not uncommon findings during shoulder arthroscopic procedures and are associated with extensive rotator cuff disease. They do not appear to be associated with glenohumeral instability, but a possible association with atypical forms of instability (subclinical or superior instability) cannot be excluded by this study. The absence of a significant association between the lesion and specific subjective symptoms or physical findings suggests that caution should be taken when attributing a specific symptom to this condition.