Arthroscopic repair of inferior glenoid labrum tears (Down Under lesions) produces similar outcomes to other glenoid tears.

Purpose: Inferior glenoid labral tears are an uncommon but distinct shoulder injury. Only a small number of studies have reported outcomes following arthroscopic repair. The aim of the current study was to report minimum 2-year outcomes following inferior labral repair and to compare outcomes and risk factors associated with the injury to non-inferior labral tears. Whether preoperative MRI or MRA identified inferior labral tears was also assessed.

Methods: A prospective study of 162 consecutive patients undergoing arthroscopic glenoid labral repair, excluding isolated superior labral tears, was conducted. Of the 130 patients available for follow-up, 18 (13.7%) had an inferior labral tear ("Down Under lesion"), the remainder had anterior, posterior or mixed anterior/posterior lesions that did not include the inferior pole. Mean follow-up time for the Down Under group was 44 months (SD 10, range 27-57), and 30 months (SD 14, range 4-60) for the non-Down Under group. Postoperative outcomes included the Oxford Shoulder Instability Score and recurrent instability. Associations between Down Under lesions and injury mechanism, instability at presentation, recurrent instability and family history were assessed with multivariable logistic regression. Preoperative MRI or MRA reports by radiologists were examined to determine if Down Under lesions were identified.

Results: Oxford Shoulder Instability Scores indicated that most patients in both groups had little pain or shoulder problems postoperatively (average Oxford Score 41; 48 = no symptoms). Oxford Scores were not significantly different between the Down Under and non-Down Under groups. Four patients (22.2%) in the Down Under group had recurring symptoms (pain and instability) compared to 12 (10.6%) in the non-Down Under group; this difference was not statistically significant (adjusted OR 1.09, 95% CI 0.19,4.77). Family history of shoulder instability was positively associated with a Down Under lesion (adjusted OR 5.0, 95%CI 1.51,16.7). MRI or MRA identified 52.9% of Down Under lesions.

Conclusion: Down Under lesions were an infrequent type of glenoid labral injury, yet postoperative outcomes were similar to other labral tears. Patients with Down Under lesions had a significant risk factor due to family history of shoulder instability. MRI and MRA could not reliably identify Down Under lesions.

Level Of Evidence: Level III.