In Vitro Evaluation of the 18 and 36 kg Securos Cranial Cruciate Ligament Repair System™

ABSTRACT

Objective—To evaluate the mechanical properties of the 18 and 36 kg Securos Cranial Cruciate Ligament Repair System^™.

Study Design—In vitro mechanical evaluation.

Sample Population—Loop constructs of 18, 27, and 36 kilogram test (kgt) nylon leader line (NLL) secured with Securos^® crimp–clamps (SCC, n=40 per NLL test weight) or by a clamped square knot (CSK; n=40/NLL test weight).

Methods—The 36 kg SCC were used for the 27 and 36 kgt NLL, and 18 kg SCC were used for the 18 kgt NLL. Loop constructs were mounted on a material testing machine, and distracted at 500 mm/min for static tests, and for cyclic tests at 500 mm/min to a distraction limit of 6 mm (18 kgt) or 7.5 mm (27 and 36 kgt) for 49 cycles, until failure. Constructs were tested at 20°C except for 1 group of 27 kgt CSK loops tested at 40°C. Load at failure, elongation, and stiffness was recorded and compared between groups under static or cyclic testing conditions.

Results—All 27 and 36 kgt loops failed by disruption of NLL contained within the knot or crimp–clamp, whereas 18 kgt SCC loops failed by the NLL pulling through the crimp-clamp. The 18 kg SCC loops had considerable variability in ultimate load and elongation (coefficient of variation 29.6% and 18.3%, respectively). There was no significant difference in elongation between 27.3 kgt CSK loops tested at 20°C and 40°C. Generally, in both static and cyclic testing, SCC constructs formed with 27.3 or 36.4 kgt NLL performed as well or better than CSK constructs, resulting in loops that were strong, underwent minimal elongation, and had high stiffness.

Conclusion—The results support use of the 36 kg Securos^® system but not the 18 kg Securos^® system (with the clamp and crimping device used). The significantly lower load required for failure, slippage through the clamp, and substantial variability suggested that the crimp tube diameter or the crimping device tested may be inappropriate for use with 18 kgt NLL.

Clinical Relevance—Surgeons should be aware that crimp–clamp design is important in controlling suture slippage or breakage within the clamp, and that novel systems should undergo mechanical testing with the size suture material they are intended to secure before clinical use.