The following factors should be considered for successful anterior cruciate ligament (ACL) reconstruction: graft choice, tunnel placement, fixation strategies, rehabilitation protocol, as well as graft tensioning and graft fixation angles at which the tension is applied intraoperatively. Graft fixation angle is an important factor associated with graft tension. Several studies have reported that wrong graft fixation angles may lead to loss of knee extension (LOE), over constraining of the knee, and graft failure. However, there is no consensus on the most appropriate knee flexion angle at the time of graft fixation in the anatomic double-bundle (AD) ACL reconstruction (ACLR). The aim of this study was to investigate whether graft fixation angles affect ligamentization of the grafts and clinical outcomes after AD ACLR.
Materials And Methods
Two hundred twenty patients (mean age 20.8 ± 9.5 years) underwent AD ACLR with semitendinosus tendon autografts. All operations were performed by one experienced surgeon. These patients consented to remove the grafts fixator and to a second-look arthroscopic examination (SL). The mean follow-up period after ACLR was 15.8 ± 4.9 months. Patients were divided retrospectively into two groups by graft fixation angle. During graft fixation, manual maximum force was applied to the anteromedial bundle (AMB) graft at 45°and to the posterolateral bundle (PLB) at 20°of knee flexion to those placed in the deep group (D group, n = 100). Force was applied to the AMB graft at 20°and to the PLB at 10°of knee flexion to those in the shallow group (S group, n = 120). The focus of the SL was on graft thickness, apparent tension, and synovium coverage of the AMB and PLB grafts. Each bundle was evaluated as excellent, fair, or poor according to the Hokkaido University classification. Functional evaluations involved instrument-measured side-to-side difference of anterior laxity (KS), peak isokinetic (60°/s) and isometric (80°of flexion) torque of the quadriceps and hamstrings, one-leg hop test and heel-height difference (HHD). Subjective evaluations included the International Knee Documentation Committee (IKDC) subjective score, Lysholm score, and the incidence of huge cyclops lesions with LOE (HHD = 30mm).
The ligamentization of the AMB and the PLB grafts in SL revealed no significant difference between each group (AMB: P = 0.17, PLB: P = 0.11). There was no significant difference between the two groups in KS (P = 0.81), mean peak isokinetic torque (quadriceps: P = 0.76, hamstrings: P = 0.82), isometric torque (quadriceps: P = 0.56, hamstrings: P = 0.81) torque, HHD (P = 0.10), one-leg hop test (P = 0.29), the IKDC subjective score (P = 0.51), and Lysholm score (P = 0.26). However, huge cyclops lesions with LOE occurred significantly lower in the S group than in the D group (15.0% vs 6.7%: P = 0.04)
There was no significant difference observed in ligamentaization and clinical outcomes of different fixation angles. Our study showed shallow graft fixation angle may have an effect on the decrease in cyclops lesions restricting knee full extension.