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Document Title: Williams-JBJS-Sep04.shtml
Article Title: Muscle and Tendon Morphology After Reconstruction of the Anterior Cruciate Ligament with Autologous Semitendinosus-Gracilis Graft
Authors: Glenn N. Williams, PT, PhD, Lynn Snyder-Mackler, PT, ScD, Peter J. Barrance, PhD, Michael J. Axe, MD and Thomas S. Buchanan, PhD
Publication: Journal of Bone and Joint Surgery (American Volume)
Date: September 2004
Volume 86, pages 1936-1946
Keywords:
(Reference-denoting numbers appear in the same font and point size as the document text. As with all Knee Library documents, this article is provided in full-text form, complete with all figures and tables.)
Comments: This study, which unfortunately only looked at patients 4-9 months post-op (a longer-term follow-up would have been highly desirable), found that hamstring-graft harvesting does indeed alter the morphology (physical attributes) of the semitendinosus and gracilis muscles (which are both part of the hamstring group), despite the fact that a certain amount of regeneration does take place. Investigation of the structures post-operatively was done through MRI imaging. The authors felt that the biceps femoris and semimembranosus muscles seem to compensate for reduced semitendinosus and gracilis function. The authors acknowledge that they did not test for hamstring strength, but they argue that morphology and cross-sectional area of tendons and muscles is well-correlated with strength. But when one compares this study to those in which dynamometers (e.g. Cybex, Biodex, Kin-Com) were used in order to rigorously test the patients at follow-up and thus to quantify the strength deficits (see, for example, Viola-AJSM-Jul00.shtml, Tashiro-AJSM-Jul03.shtml, Tadokoro-AJSM-Oct04.shtml, Armour-AJSM-Oct04.shtml, and Segawa-AJARS-Feb02.shtml), then the strength deficits arising from hamstring-graft harvesting become glaringly apparent. (These strength deficits are especially noticeable at deep flexion angles, and thus tend to be particularly problematic for people who are involved in activities such as gymnastics, wrestling, and martial arts.) Clearly, there is more to evaluating hamstring-group strength than simply a visual examination of MRI images. And, there is no substitute for having a high-quality dynamometer. As a final note, it would also have been nice if the number of subjects would have been more than just 8.
Abstract
Background: The autologous semitendinosus-gracilis graft is the first choice of many orthopaedic surgeons when reconstructing the anterior cruciate ligament. The effect that graft harvest has on muscle and tendon morphology remains unclear. The purpose of this study was to describe these effects more completely.
Methods: Magnetic resonance images were acquired from eight patients before the anterior cruciate ligament reconstruction with semitendinosus-gracilis autograft and then again postoperatively after they had returned to sports. Muscle and tendon morphology was described by determining the volume and peak cross-sectional area of each structure on digitally reconstructed images. The effects that the procedure had on muscle and tendon length were evaluated separately and then together as a muscle-tendon complex.
Results: Anterior cruciate ligament reconstruction with semitendinosus-gracilis autograft resulted in a marked decrease in volume, cross-sectional area, and length of the semitendinosus and gracilis muscles. Tendon regeneration occurred in varying degrees in nearly all subjects. The morphology of the biceps femoris and semimembranosus muscles suggested that they had been compensating for the reduced semitendinosus and gracilis muscle function. Although semitendinosus and gracilis muscle retraction occurred following tendon stripping, nearly all of the subjects displayed evidence of at least partial tendon regeneration.
Conclusions: Anterior cruciate ligament reconstruction with semitendinosus-gracilis autograft had a marked impact on semitendinosus and gracilis muscle morphology. However, this altered muscle morphology did not appear to have a clinically important impact on short-term outcomes. The biceps femoris and semimembranosus muscles appear to compensate for reduced semitendinosus and gracilis function. Tendon regeneration is observed in most people, but it is often incomplete at six months.
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