Biomechanical superiority of partial-thickness tendon split and bridging repair after BPTB graft harvest for ACL reconstruction

Reconstruction of the anterior cruciate ligament (ACL) with a bone-patellar tendon-bone (BPTB) autograft leaves a central tendon defect, and whether this should be repaired remains debated. Conventional suturing techniques often show limited biomechanical benefit. This study evaluated the biomechanical efficacy of a novel Partial-Thickness Split and Bridging Repair (PTSBR) technique compared with non-repair in a cadaveric model.

Twelve knees from six fresh-frozen human cadavers were randomized to repair or non-repair groups. In the repair group, PTSBR involved a longitudinal partial-thickness incision with superficial tendon bridging and interrupted vertical mattress sutures. All specimens were mounted and tested using an Instron universal testing machine. Primary outcomes included maximal load, maximal stress, stiffness, Young's modulus, tendon dimensions, and failure location. Statistical comparisons were performed using paired analyses with significance set at p < 0.05.

PTSBR demonstrated significantly higher Young's modulus [90.19 MPa (24.02-202.47) vs. 50.83 MPa (19.96-115.29), p = 0.028] and maximal stress [19.35 MPa (5.21-35.54) vs. 13.30 MPa (5.21-24.23), p = 0.046] compared with non-repair. No difference was observed in maximal load (p = 0.674) or stiffness. Tendon thickness was significantly reduced in the repair group (2.34 ± 0.20 mm vs. 2.69 ± 0.32 mm, p = 0.023). Failure occurred mainly at the tibial or patellar attachment, with no mid-substance ruptures.

The PTSBR technique enhanced tensile stiffness and stress resistance compared with non-repair, likely due to improved tendon fiber alignment and load-sharing. These biomechanical advantages suggest that PTSBR may represent a clinically relevant advancement in managing patellar tendon defects after BPTB graft harvest.