Effect of diameter reduction by compression on peroneus longus allograft integrity: A biomechanical analysis

There is broad consensus regarding the minimum required graft diameter in anterior cruciate ligament (ACL) reconstruction surgery; a diameter of at least 8 mm is recommended when using hamstring tendon grafts. However, it remains unclear what happens when a larger-diameter graft is compressed to a smaller diameter, and how this alteration may affect the biomechanical properties of the graft. The objectives is determine whether the biomechanical strength of compressed allografts is preserved after reducing their diameter, and whether compression techniques could be considered a viable option for smaller patients such as women and children. Our hypothesis is that a compressed graft may retain similar strength to the original, despite having a reduced diameter.

This was a cadaveric biomechanical case-control study using 30 peroneus longus (PL) tendon allografts. The grafts were divided into three groups: Group 0 (8 mm uncompressed grafts), Group 1 (9 mm uncompressed grafts), and Group 2 (10 mm with a graft tube, compression to 9 mm). Each graft was tested using a Zwick/Roell Z005 tensile testing machine, undergoing cyclic loading between 50 and 250 N at 1 Hz for 1000 cycles, followed by continuous tensile loading to failure. The maximum failure force (Fmax) was recorded for each graft. Statistical analyses were performed using STATA v.18.5.

Group 1 (9 mm uncompressed grafts) showed a mean maximum failure force of 1902 N (SD: 432.12; 95 % CI). Group 2 (compressed grafts) showed a mean Fmax of 1608 N (SD: 233.12; 95 % CI), with a statistically significant difference between the two groups (p = 0.037). Group 0 (native 8 mm grafts) showed a mean Fmax of 1341 N (SD: 936.67; 95 % CI). No statistically significant difference was found between Group 0 and Group 2 (p = 0.196).

The results indicate that the compressed group had lower resistance compared to the original 9 mm grafts. However, when compared to the smaller-diameter grafts, no significant difference in strength was observed. Nonetheless, the compressed grafts showed a tendency to withstand higher loads than the native 8 mm grafts.