Biomechanical Assessment of a Novel Posterior Soft Tissue Repair Technique in Primary Total Hip Arthroplasty

Instability is one of the most common complications after total hip arthroplasty (THA), particularly when using the posterior approach. Repair of the posterior capsule has proven to significantly decrease the incidence of posterior hip dislocation. The purpose of the present study is to evaluate if a racking hitch knot utilizing a 2mm braided polyblend suture provides a stronger repair of the posterior soft tissues when compared to a traditional repair utilizing a non-absorbable suture after a posterior approach to the hip.

Ten cadaveric hips from donors, who were at a mean age of 80 ± 9 years old at the time of death, were evaluated after posterior soft tissue repair utilizing two different techniques. Five specimens were repaired utilizing a racking hitch knot with a 2mm braided polyblend suture (FiberTape®, Arthrex GmbH, Naples, Florida) and five other specimens were repaired with a traditional repair using a no. 2 non-absorable suture (FiberWire®, Arthrex GmbH, Naples, Florida). Cadaveric specimens were matched based upon age, sex, and laterality. Biomechanical tensile testing using the Instron E10000 Mechanical Testing System and the mechanisms of failure (MOF) were assessed.

The ultimate load to failure was three times higher using braided polyblend sutures (390.00 ± 129.08 N) compared to non-absorbable sutures (122.81 ± 82.41 N) after posterior soft tissue repair (p<0.01). In the braided polyblend suture cohort, the mechanism of failure most commonly occurred as the braided suture pulled through the posterior soft tissues. However, in the non-absorbable suture repair, failure took place at the suture knot.

The use of our posterior capsular repair utilizing a braided polyblend suture and racking hitch knot provides for a stronger repair of the posterior soft tissues when compared to non-absorbable suture repair following a posterior approach to the hip joint.