A biomechanical analysis of anterior Bankart repair using suture anchors.

BACKGROUND

Arthroscopic repair of anterior Bankart lesions is typically done with single-loaded suture anchors tied with simple stitch configuration.

HYPOTHESIS

The knotless suture anchor will have similar biomechanical properties compared with two types of conventional suture anchors.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fresh-frozen shoulders were dissected and an anteroinferior Bankart lesion was created. For phase 1, specimens were randomized into either simple stitch (SSA) or knotless suture anchors (KSA) and loaded to failure. For phase 2, specimens were randomized into 1 of 4 repair techniques and cyclically loaded then loaded to failure: (1) SSA, (2) suture anchor with horizontal mattress configuration, (3) double-loaded suture anchor with simple stitch configuration, or (4) KSA. Data recorded included mode of failure, ultimate load to failure, load at 2 mm of displacement, as well as displacement during cyclical loading.

RESULTS

For phase 1, the load required to 2 mm displacement of the repair construct was significantly greater in SSA (66.5 +/- 21.7 N) than KSA (35.0 +/- 12.5 N, P = .02). For phase 2, there was a statistically significant difference in ultimate load to failure among the 4groups, with both the single-loaded suture anchor with simple stitch (184.0 +/- 64.5 N), horizontal mattress stitch (189.0 +/- 65.3N), and double-loaded suture anchor with simple stitch (216.7 +/- 61.7 N) groups having significantly (P < .05) higher loads than the knotless group (103.9 +/- 52.8 N). There was no statistically significant difference (P > .05) among the 4 groups in displacement after cyclical loading or load at 2 mm of displacement.

CONCLUSION

Both knotless and simple anchor configurations demonstrated similar single loads to failure (without cycling); however, the knotless device required less single load to displace 2 mm. All repair stitches, including simple, horizontal, and double-loaded performed similarly.

CLINICAL RELEVANCE

The findings may suggest that with cyclical loading up to 25 N there is no difference in gapping greater than 2mm, but a macrotraumatic event may demonstrate a difference in fixation during the initial postoperative period. Additional in vivo studies are needed to determine whether these differences affect the integrity of the repair construct and, ultimately, the clinical outcome.