Mechanical Evaluation of Suture Docking Method Versus Novel Tensegrity Suture Screw in Treating Varus Posterolateral...

Elbow instability often arises from collateral ligament (LUCL) complex failure, causing varus and posterolateral rotatory subluxations. Conventional docking repair requires technical expertise balancing slack and tension. Existing suture anchors lack adjustable tensioning and rely on bone tunnel length for mechanical performance. A novel tensegrity-based suture anchor system was developed to enhance implant-bone fixation and optimize suture tensioning for early stability.

Static three-point bending tests were conducted using Sawbones (n = 20) and paired cadaveric elbows (n = 14) with either conventional suture docking (CON) or elbow tensegrity screw (TEN). Force-displacement relationships were plotted. Stiffness, maximum force, and displacement at peak force were measured and compared using nonparametric Mann-Whitney U tests in GraphPad Prism 10.5.0.

In foam elbows, TEN demonstrated significantly higher stiffness (3.46 ± 1.44 N/mm) than CON (1.44 ± 1.17 N/mm, p < 0.01). Maximum forces were 132.60 ± 28.82 N for TEN versus 75.02 ± 20.28 N for CON (p < 0.01), while displacement at peak force was slightly lower in TEN (35.54 ± 5.80 mm) versus CON (39.03 ± 9.05 mm, p = 0.22). In cadaveric elbows, TEN also had greater stiffness (12.79 ± 9.73 N/mm) versus CON (3.53 ± 2.43 N/mm, p < 0.05). Maximum forces were significantly greater for TEN (199.93 ± 35.89 N) compared to CON (140.11 ± 37.23 N, p < 0.05), while displacements at peak force were lower in TEN (22.31 ± 10.06 mm) than CON (38.68 ± 8.64 mm, p < 0.05). All CON samples failed from irreversible yielding and suture stretching, whereas most TEN samples failed due to suture rupture, suggesting superior bone-implant and suture-implant interface resistance.

TEN devices significantly improved mechanical strength and pretensioning over conventional docking, enhancing early stability and reducing yield failure risk.