One-Year Serial Follow-up Magnetic Resonance Imaging Study of RigidFix for Femoral Fixation in Anterior Cruciate Ligament Reconstruction

Purpose To assess graft slippage at the site of femoral fixation by follow-up magnetic resonance imaging (MRI) after anterior cruciate ligament (ACL) reconstruction with a four-strand autogenous hamstring tendon using RigidFix (DePuy Mitek). Materials and Methods Twenty-one subjects diagnosed with ACL rupture underwent ACL reconstruction using hamstring autograft with the transtibial technique. RigidFix was used for femoral fixation and Intrafix and washer screw were used for tibial fixation. Follow-up MRIs were taken immediately after surgery and at 1, 3, 6, and 12 months after surgery. Slippage of the graft and breakage of the RigidFix cross-pin were assessed. Side-to-side difference (SSD) on stress radiographs was measured to assess residual laxity. Results Mean slippage of the graft was 0.21±0.31 mm at one year after surgery. Cross-pin breakage was noted in two subjects: in one subject, immediately after surgery and in the other subject, at 6 months after surgery. Mean SSD was 1.32±1.07 mm at the last follow-up. The correlation coefficient between graft slippage and SSD was 0.131 (p=0.571). Conclusions RigidFix is a stable fixation device for hamstring autograft with minimally statistically significant but clinically insignificant graft slippage. Cross-pin breakage did not affect the clinical outcomes. Careful preparation of the graft is needed for performing the technique correctly.