Abstract
Aims: To determine load to failure for four different meniscal repair techniques, and to assess gapping across repairs under cyclical loading.
Background: Studies comparing the biomechanical properties of different meniscal repair systems are limited, and most have simply investigated load to failure. Meniscal tissue is highly anisotropic, and far weaker under tension in the radial direction. Load to failure using high loads may, therefore, not be the most physiologically relevant in-vitro test for repair of circumferential tears, and measuring increases in gapping across repair sites under cyclical loading at lower loads may be of greater importance.
Methods: Bovine menisci were divided vertically, 5mm from the peripheral edge to simulate a circumferential tear, and then repaired using one to four techniques: vertical loop sutures using 1 -PDS, bioabsorbable Meniscal Arrows (Atlantech), Meniscal Fasteners (Mitek) or T-Fix Suture Bars (Acufex). Nine specimens were tested in each group using an Instron 5500 materials testing machine to determine load to failure. A further nine specimens in each group were tested by cyclic loading between 5N and 10N at 20mm/min for 25 cycles, using a digital micrometer to measure initial gapping, and a Differential Variable Reluctance Transducer to measure the progressive increase in gapping across the repair site during the cyclical loading. Data was analysed by ANOVA and Tukey’s multiple comparison post test using Prism (GraphPad) software.
Results: The mean loads to failure (with s.d.) in Newtons were: Sutures 72.7 (22.0), Arrows 34.2 (15.4), Fasteners 40.8 (13.4), and T-Fix 49.1 (13.8). The load to failure was significantly greater with the Sutures compared to the Arrows (p< 0.001), the Fasteners (p< 0.001) or the T-Fix (p< 0.05).
The mean gapping across the repairs after 25 load cycles (with s.d.) in millimetres was: Sutures 3.3 (1.0), Arrows 2.2 (0.9), Fasteners 4.0 (0.6) and TFix 3.5 (0.7). The mean gapping was significantly less for the Arrows compared to the Sutures (p< 0.05), the Fasteners (p< 0.01), or the T-Fix (p< 0.05).
Conclusions: These results confirm that meniscal repair by suturing gives the highest load to failure, but show that Arrows give superior hold with the least increase in gapping across a repair under cyclical loading by this test protocol.
The abstracts were prepared by Mr Roger Smith. Correspondence should be addressed to him care of the British Orthopaedic Association, Royal College of Surgeons, 35-43 Lincoln’s Inn Fields, London WC2A 3PN.
