Article
The Relationship between Isokinetic Quadriceps Strength and Laxity on gait Analysis in AACL-Reconstructes knees
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Published: | October 19, 2004 |
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Gait alterations after ACL-reconstruction have been reported in the literature. In the current study, a group of 14 patients who all had an ACL-reconstruction with a patellar tendon autograft were examined. Kinetic and kinematic data were obtained from the knee during walking. The Flexion-Extension-Deficit (FED) calculated from the angular difference between maximal flexion and maximal extension during the stance phase in the ACL-reconstructed and the normal knee was measured. We analyzed whether these alterations in gait were related to quadriceps strength and residual laxity of the knee. It may be that patients modify their gait patterns to protect the knee from excessive anterior translation of the tibia by reducing the amount of extension during stance. On the other hand persistent quadriceps weakness may also cause changes in gait patterns as the quadriceps is functioning as an important dynamic stabilizer of the knee during stance. Results showed that patients had a significantly higher FED value of 4.9 ± 4.0 when compared to data obtained from a healthy control group in a previous study who had a FED 1.3 ± 0.9. This is mainly caused by an extension deficit during mid stance. External extension moments of the knee TZMAX [Nm/kg] were significantly lower in the current patients group when compared to a healthy control group (TZMAX [Nm/kg] patients -0.27 ± 0.19 versus -0.08 ± 0.06 in control group). Correlation coefficient analysis did not show any positive relationship between quadriceps strength and gait analysis parameters. Furthermore no correlation was found between the amount of laxity of the knee and gait. The clinical relevance of this study showed that the measured gait alterations cannot be solely explained by often used biomechanical indicators such as laxity and strength. It appears that gait alterations after ACL-reconstruction are the result of the surgical procedure with subsequent modified motor programming.