A comparison of four tibial-fixation systems in hamstring-graft anterior ligament reconstruction.

The aim of this study was to evaluate at time-zero four tibial fixations on four major criteria: the elongation and cyclic stiffness of the hamstring graft construct under cyclic loading, the yield load and pullout stiffness under load at failure. Four fixation systems were tested: the Delta screw, the WasherLoc, the TightRope Reverse and the tape locking screw on 32 tibiae of adult pigs using 32 pairs of human semitendinosus and gracilis tendons. Two tests were performed: cyclic tests using loads at 70-220 N, to measure the elongation at the end of the cycles, followed by load-to-failure testing to measure the yield load and the cyclic stiffness. The mean elongation was 1.23 mm for the TLS, 3.81 mm for the Delta, 3.59 mm for the WasherLoc and 3.91 mm for the TightRope. The mean yield loads and SD were 1,015 ± 129 N for the TLS, 844 ± 394 N for the Delta, 511 ± 95 N for the WasherLoc and 567 ± 112 N for the TightRope. The results showed the significant superiority of TLS and Delta over WasherLoc and tibial TightRope in regard to yield load. The results showed the significant superiority of TLS over the other fixations in regard to slippage. The TLS system and the Delta screw provide a better quality of primary fixation to the tibia, but further in vitro studies are needed.

Objective evaluation of anterior knee laxity; comparison of the KT-1000 and GNRB® arthrometers.

PURPOSE: Accurate measurement of laxity after anterior cruciate ligament (ACL) rupture is usually performed with the KT-1000 arthrometer, and reproducibility and reliability are discussed. A new arthrometer, the GNRB(®), has been recently developed in an attempt to improve intra- and inter-examiner reproducibility. The aim of this diagnostic study was to evaluate the intra- and inter-examiner reproducibility of the GNRB(®) and the KT-1000. METHODS: Three protocols were designed to evaluate and compare the two arthrometers. Fifteen physiotherapists conducted tests on 15 subjects with healthy knees. The intra- and inter-reproducibility of the two tests were compared by analysis of variance and the F-test. RESULTS: Measure reproducibility was significantly worst with the KT-1000 than with the GNRB(®) (machine effect, P < 0.001) regardless of operator experience. There was no significant difference between experienced and inexperienced examiners with the GNRB(®) (no 'examiners effect'). Regardless of the machine, there was a 'side effect' with healthy knees. CONCLUSION: This clinical study demonstrates the superior intra- and inter-examiner reproducibility of the GNRB(®) over the KT-1000. There appears to be some technological advantages to using the GNRB(®) including pressure control of the patella, accuracy of the displacement transducer, control of the load on the calf, and control of hamstring activity. LEVEL OF EVIDENCE: Diagnostic study, Level I.