Hamstring tendon harvest for ACL reconstruction: impact on muscle and function

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McRae, Sheila MB
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Background: Semitendinosus-gracilis (STG) autograft continues to increase in ACL reconstruction and a comprehensive study of the impact of what is essentially ‘surgically induced tenotomy’ of STG has not been undertaken. Purpose: To examine longitudinal changes in muscle morphometry and physical activity (PA) in relation to strength, functional tests, and subjective outcomes. Methods: Assessments at pre-, 2-weeks, 6- and 12-months post-surgery were performed on twenty moderately active adults undergoing ACL reconstruction. Participants were randomized to the Standard group (using STG tendon from the ACL deficient limb) or the Contra group (using STG from the opposite limb). Bilateral lower extremity MRI, Tegner, Lysholm, and IKDC scores, hop tests, and isovelocity strength testing in a seated and hipneutral supine position were completed. PA was assessed using a tri-axial accelerometer (GTX3, Actigraph, Pensacola, FL). Results: Subjective scores significantly improved from pre- to 12-months post-surgery, although Tegner score was significantly less (-1.25 levels) than pre-injury scores at 12- months. ST and G CSA significantly declined in donor limbs to 41.5% and 65.5% of presurgery,respectively and there was a 5.7 (2.9) cm proximal shift in ST and a 4.2 (2.3) cm shift in G donor muscles. In the donor limb, nine of 17 participants for ST and one for G had more than an 80% reduction in volume. There was significant difference between donor and non-donor limbs in peak knee flexor torque, but only in the hip-neutral testing position. There were no differences in hop tests between legs regardless of reconstruction or STG tendon harvest. PA did not significantly improve from pre-surgery, but was comparable an age-matched normative population. This level was less than that necessary for a healthy lifestyle (10,000 steps). Morphological parameters were moderately or highly predictive of outcomes in subjective findings, single hop test, PA, and strength. Conclusion: Changes in muscle morphology following tendon harvest of ST and G were found to be related to measured decreases in knee flexor strength, and post-operative deficiencies in objectively measured PA, hop tests, and subjective findings at 12-months post-surgery. PA did not increase in a statistically or clinically relevant degree consistent with a diminished self-report of function.
ACL, muscle, hamstring