Type II SLAP lesions: three subtypes and their relationships to superior instability and rotator cuff tears.

One hundred two type II SLAP lesions without associated anterior instability, Bankart lesion, or anterior inferior labral pathology were surgically treated under arthroscopic control. There were three distinct type II SLAP lesions based on anatomic location: anterior (37%), posterior (31%), and combined anterior and posterior (31%). Preoperatively, the Speed and O'Brien tests were useful in predicting anterior lesions, whereas the Jobe relocation test was useful in predicting posterior lesions. Rotator cuff tears were present in 31% of patients and were found to be lesion-location specific. In posterior and combined anterior-posterior lesions, a drive-through sign was always present (despite absence of anterior-inferior labral pathology or a Bankart lesion) and was eliminated by repair of the posterior component of the SLAP lesion. We conclude that SLAP lesions with a posterior component develop posterior-superior instability that manifests itself by a secondary anterior-inferior pseudolaxity (drive-through sign), and that chronic superior instability leads to secondary lesion-location-specific rotator cuff tears that begin as partial thickness tears from inside the joint.