As he said, my name is Will Holden. Welcome and thank you for coming to my talk. This study was conducted by the Moon Knee MRI Group and the Program for Advanced Musculoskeletal Imaging at Cleveland Clinic, led by Dr. Carl Wernosky and Dr. Xiaojuan Li. This study is funded by two NIH R1 grants. I have no financial interest to disclose. So the hypothesis for this study is that the functional recovery of the semitendinosus and gracilis is impaired following harvest for hamstring autograft ACL reconstruction. While we know that the hamstring tendons can regenerate after harvest, a regenerated tendon is not adequate if the muscle itself cannot fully function. Our study includes 120 patients from the Moon Onsite Nested Cohort at least 10 years after ACL reconstruction. Patients were accrued from Cleveland Clinic, Ohio State, and Vanderbilt University. And there are 63 bone patellar tendon bone autographs, 52 hamstring tendon autographs, 20 of which were isolated semitendinosus harvest, and 27 controls matched for age, sex, and BMI. The patients are nearly half male, half female, range from 26 to 48 years old, and are at a healthy BMI. The readers were all blinded to the ACL reconstruction type. And the thigh and knee sequences are listed here. So in this study, we measured the mid-thigh cross-sectional area, the mid-thigh fat fraction, and the location of the myotennis junction distance to the joint line. Our analysis compared the ACL reconstructed knee to the contralateral normal knee within each patient and looked at averages across the ACL reconstruction type and among controls. We observed significantly lower average mid-thigh muscle cross-sectional area in the hamstring muscles of patients who received hamstring tendon autographs versus patients who received BTB autographs. And we observed significantly more average mid-thigh fat infiltration in the hamstring muscles of patients who received hamstring tendon autographs versus BTB autographs. And we observed many cases of incomplete hamstring tendon regeneration. So a summary table is shown here. So this image here shows an example of semitendinosus tendon regeneration and fatty atrophy. This shows an example of semitendinosus without tendon regeneration and a complete absence of muscle. And the far right image here shows a side-to-side comparison of the myotennis junction after harvest with clear retraction in the operated limb. So we also observed significantly more average myotennis junction retraction in these patients who received hamstring tendon autographs versus BTB autographs. So the question at the heart of our research effort is, Doc, how will my hamstrings function after you harvest two of my tendons? To answer this question, we categorized the hamstring autograph patients within each outcome measure into normal, moderate and severe categories. And here are the individual patients' side-to-side differences in cross-sectional area for the semitendinosus and gracilis. Here are the individual patients' side-to-side differences in fatty infiltration for the semitendinosus and gracilis. And here are the individual patients' side-to-side differences in the myotennis junction distance to the joint line for the semitendinosus and gracilis. So putting it all together, the majority of hamstring tendons regenerate after harvest. However, they are left with a lower muscle cross-sectional area, they have more muscle fatty infiltration, and the myotennis junction is shifted approximately. When you put all of our findings together, about one-third of harvested hamstring tendons regain normal function, around one-third have partial function, and around one-third have minimal function. That's the end of my talk. Thanks for joining. Special thanks to the Moon Group, NIH, Arthritis Foundation, PAMI, and the Biomedical Engineering Department at Cleveland Clinic.

ACL reconstruction

muscle recovery

hamstring tendons

muscle size

fatty infiltration