Compression Suture Staple Repair of Simulated Gluteus Medius Partial Tendon Tears Provides Increased Contact Pressure Compared With Stepwise Bridged Repair.

Abstract

Purpose: To examine the contact mechanics of 2 different suture anchor configuration constructs for gluteus medius repair in partial-thickness tears and to define an optimal distance for anchor placement in a biomechanical model.

Methods: Trochanteric bone was simulated using polyurethane foam blocks, and a polyurethane rubber was used as a surrogate for the gluteus medius tendon tissue. As the rubber remained partially attached to the foam, this design simulated a partial-thickness tear without any retraction of the tendon tissue. A pressure sensor was used to collect contact data. Repairs were performed with knotless suture anchors. Three different 2-anchor repair interval distances (10, 15, and 20 mm) were first tested to define the optimal distance for anchor placement. We then performed 2 different 3-anchor repairs (stepwise bridged and compression suture staple) using the optimal distance. Pressure data were collected and compared between 3-anchor groups.

Results: Results from the 2-anchor interval distance testing showed an overall significant effect for contact force (P < .001), area (P < .001), and pressure (P = .01), with 15 mm being the optimal distance to exert the most pressure. Results from the 3-anchor testing at 15 mm between anchors showed that contact pressure on the surrogate tendon was significantly (P = .04) greater for the compression suture staple technique (208.5 ± 61.6 kPa) compared with the stepwise bridged technique (143.4 ± 41.4 kPa).

Conclusions: In this biomechanical study, the compression suture staple technique exerted more pressure than the stepwise bridged repair technique at time 0 with no cyclic loading. Additionally, 15 mm had the greatest contact pressure of those examined for anchor placement using knotless suture anchors for these repairs.

Clinical relevance: By studying the contact mechanics of different suture anchor configurations, we determined which setup may provide better compression of the tendon onto the bone.