Purpose: To identify the rate and risk factors of posterior labral involvement in operatively managed Bankart lesions and assess the effectiveness of MRI arthrogram for preoperative identification of such injury patterns.
Methods: A consecutive cohort of patients undergoing arthroscopic Bankart repair were retrospectively reviewed. All subjects underwent a prearthroscopy MRI arthrogram. Operative findings were used as the gold standard for posterior labral tear extension. Patient demographic and surgical data were then analyzed to identify independent factors associated with the presence of concomitant posterior labral injury.
Results: Of 124 patients undergoing arthroscopic Bankart stabilization, 23 (19%) were noted to demonstrate posterior labral injury on arthroscopic evaluation. Factors associated with injury to the posterior labrum included those sustaining two or fewer dislocations events (P =.001), an earlier average presentation (P = .001), and a reported "contact" mechanism of dislocation (P = .02). Posterior labral involvement did not correlate with surgical positioning (beach-chair versus lateral) or the need for revision surgery. On the basis of review of preoperative imaging, MRI arthrogram demonstrated a sensitivity of 83% and a specificity of 95% for detection of posterior labral injury.
Conclusions: Posterior propagation of Bankart lesions is relatively common following shoulder dislocations, with a rate of 18.5%. Risk factors for posterior labral extension include two or fewer dislocations, early presentation from the time of injury, and contact sports. On the basis of these findings, careful assessment of the posterior labrum on MRI arthrogram may reveal the majority, but not all, of these lesions.
Level of evidence: Level III, retrospective case-controlled study.
© 2021 The Authors.