RESUMO
OBJECTIVE: Mechanical evaluation of 2 suture constructs for extracapsular stifle stabilization. STUDY DESIGN: In vitro study. SAMPLE POPULATION: Crimped interlocking loop constructs (ILC) of 45 kg nylon leader line (NLL) and Orthofiber® (OF). METHODS: ILC were tightened to 100 N, then crimp secured. Ramp to failure (n=10/group)-Data were derived from force/displacement plots. Stress-relaxation testing (n=10/group)-ILC's were nondestructively loaded and held at resultant displacement as force data were recorded. Incremental, cyclic loading (n=10/group)-ILC's were loaded (5 cycles/set) starting at 100 N and incrementally increased by 50 N (1 and 3 Hz protocols). Loop tension and elongation were recorded after each set. RESULTS: Ramp to failure-initial loop tension was similar (NLL 75.5 ± 9.5 N; OF 68.7 ± 10.4 N, P=.140). Tested OF constructs were stiffer (NLL 125.7 ± 4.0; OF 234.6 ± 25.0 N/mm, P≤.001), had lower yield load (NLL 193.6 ± 13.8; OF 137.3 ± 94.3 N, P≤.001), lower peak load (NLL 873.7 ± 68.6; OF 653.6 ± 80.2 N, P≤.001), and lower elongation at failure (NLL 19.1 ± 1.4; OF 5.2 ± 1.0 mm, P≤.001) and at yield (NLL 1.52 ± 0.2; OF 0.3 ± 0.6 mm, P=.003) than NLL constructs. Yield in NLL ILC's was variable knot tightening/crimp slippage, but only crimp-suture slippage in OF. Stress-relaxation testing-OF demonstrated greater relaxation. Incremental, cyclic loading-induced ILC elongation and tension loss in both groups, independent of loading frequency. NLL lost tension at lower rate, but elongated more than OF. CONCLUSIONS: NLL construct is mechanically superior to OF construct.
