2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


Biomechanical Evaluation of the Surgical Reconstruction for Chronic Hamstring Injury: Comparison of Using an Achilles Tendon Graft and Distal Hamstring Graft

Haruki Nishimura, MD, PhD JAPAN
Shintaro Mukohara, MD, Kobe JAPAN
Kiminari Kataoka, MD, Kobe, Hyogo JAPAN
Justin Hollenbeck, MS, Vail, Colorado UNITED STATES
Soshi Uchida, MD, PhD, Kitakyushu, Fukuoka JAPAN
Marc J. Philippon, MD, Vail, CO UNITED STATES

Steadman Philippon Research Institute, Vail, Colorado, UNITED STATES

FDA Status Not Applicable

Summary

Proximal hamstring reconstruction with the semitendinosus tendon allograft was found to have a higher failure load and lower percent difference of native stiffness compared to reconstruction with an Achilles tendon allograft.

Abstract

Background

Proximal hamstring tendon injuries are common and may require surgery after failing conservative treatment. In chronic cases with significant proximal hamstring tendon retraction, allografts are commonly used for an augmented repair, but it remains unclear whether using a distal hamstring or an Achilles allograft has superior biomechanical performance.

Objectives: To biomechanically compare the failure load, stiffness, and number of cycles until failure of proximal hamstring reconstruction techniques using a semitendinosus tendon allograft and an Achilles tendon allograft.

Methods

Eight pairs of fresh-frozen human cadaveric hemi-pelvises were included in this study. Achilles tendon and semitendinosus allografts were acquired from a graft supplier. Specimens underwent non-destructive testing in their native state to assess native linear stiffness. Each pair of specimens were randomly assigned to receive the reconstruction with an Achilles tendon allograft or with a semitendinosus allograft. After surgical repair, the specimens underwent biomechanical testing consisting of a preconditioning phase followed by a pull to failure to assess failure load, elongation at failure, stiffness, and mode of failure.

Results

The Achilles tendon allograft group had a significantly lower failure load than the semitendinosus group (213 ± 48 N vs. 366 ± 85 N; p=0.005). There was no difference in elongation at failure between the Achilles and semitendinosus groups (21.0 ± 10.2 mm vs. 25.0 ± 10.4 mm; p=0.457). In the Achilles group, all failures occurred via suture pullout at the proximal end of the graft. In the semitendinosus group, the most common mode of failure was via suture pullout at the proximal end of the graft, and specimens also failed via suture anchor pullout, suture pullout of a suture anchor, failure at the muscle, and failure at the muscle/graft interface. Native stiffness was not significantly different between the Achilles and the semitendinosus groups (49.8 ± 12.6 N/mm vs. 51.4 ± 10.8 N/mm; p=0.995). Reconstruction stiffness was not significantly different from native stiffness of the Achilles group (45.2 ± 13.7 N/mm vs. 49.8 ± 12.6 N/mm; p=0.881). Reconstruction stiffness was not significantly different from native stiffness of the semitendinosus group (51.7 ± 12.4 N/mm vs. 51.4 ± 10.8 N/mm; p=1.00). The Achilles group exhibited a significantly higher percent difference of native stiffness as compared to the semitendinosus group (34.4 ± 14.1 % vs. 13.1 ± 6.4 %; p=0.003).

Conclusion

Proximal hamstring reconstruction with the semitendinosus tendon allograft was found to have a higher failure load and lower percent difference of native stiffness compared to reconstruction with an Achilles tendon allograft. These results demonstrate time-zero biomechanical superiority of reconstruction using a distal hamstring allograft vs. reconstruction using an Achilles tendon allograft.