Five- and six-strand hamstring grafts consistently produce appropriate graft diameters for anterior cruciate ligament reconstruction

Purpose: Hamstring tendon graft diameter less than 8 mm has been correlated with an increased risk of anterior cruciate ligament reconstruction (ACLR) graft failure. The purpose of this study was to measure and compare the diameter of 3-, 4-, 5-, and 6-strand gracilis and semitendinosus (ST) hamstring tendon (HT) ACLR grafts, and to determine if there is a correlation between anthropometric data, HT length, and diameter of the HT ACLR graft.

Methods: Male patients (n = 78) undergoing primary or revision ACLR with a HT autograft between July 2018 and March 2020 were recruited. Pre-operative anthropometric data was collected. Gracilis and ST tendons were harvested and the length and diameter measured. The following HT graft configurations were prepared in each patient: triple ST; double gracilis + double ST; double gracilis + triple ST; triple gracilis + triple ST. Paired t-tests and Pearson's correlation coefficients were used to assess demographics, anthropometrics, graft diameter, and tendon length. A non-parametric test was used to compare femoral and tibial ACL graft diameters of the 3-, 4-, 5-, and 6-strand HT graft configurations.

Results: For the femoral end, 10%, 19%, 69% and 86% of the patients achieved graft diameters of equal to or greater than 8 mm in 3-, 4-, 5- and 6-strand HT graft configurations respectively. For the tibial end, 27%, 10%, 83%, and 92% of the patients achieved graft diameters of equal to or greater than 8 mm in 3-, 4-, 5-, and 6-strand HT graft configurations respectively. The largest increases in HT graft diameters were noted between the femoral end of 6- vs. 3-strand grafts (mean difference 1.7 ± 0.5 mm; p < 0.001) and between the tibial end of 6- vs. 4-strand grafts (mean difference 2.0 ± 0.5 mm; p < 0.001). Height and leg length were moderately positively correlated with ST tendon length (r = 0.54-0.51) and gracilis tendon length (r = 0.52-0.45), and thigh and shank lengths were moderately positively correlated with ST tendon length (r = 0.43 and 0.40, respectively).

Conclusion: Traditional 4-strand HT ACL autografts in male patients undergoing ACLR in the United Arab Emirates result in graft diameters less than 8 mm in the majority of patients.

Level of evidence: III.