Background: Longer term studies of bioabsorbable screws for ACL reconstruction are reported, but results are specific to the exact screw material and design. Titanium and PLLA-HA screw outcomes have been compared only to 2 years.

Purpose: The aim of this study was to compare the clinical and radiological outcomes of PLLAHA screw (BS) versus a titanium screw (TS), for hamstring tendon anterior cruciate ligament reconstruction over 5 years. We hypothesized that there are no differences in clinical scores, and tunnel widening, between the BS and the TS groups, and that the PLLA-HA screw as seen on MRI should show high grade resorption and ossification response over 5 years.

Methods: 40 patients undergoing ACLR were randomized to receive either a PLLA-HA screw (BS group) or a Titanium screw (TS group) for ACL fixation. Blinded evaluation was performed at 2 & 5 years with IKDC & Lysholm knee score, KT-1000 arthrometer, single legged hop test, and MRI to evaluate tunnel and screw volumes, peri-screw ossification, graft integration and cyst formation.

Results: There was no difference in any clinical outcome measure at 2 or 5 years between the 2 groups. At 2 years, the BS femoral tunnel was smaller than the TS tunnel (p=0.02) and at 5 years, there was no difference. At 2 years the femoral BS screw was a mean 76% of its original volume and by 5 years, 36%. At 2 years the tibial BS screw mean volume was 68% of its original volume and by 5 years, 46%. At 5 years BS group 88% of femoral tunnels and 56% of tibial tunnels demonstrated a significant ossification response. There was no increase in cyst formation in the BS group and no screw breakages.

Conclusion: Our study has shown equivalent clinical results between BS and TS groups at 2 and 5 years. This PLLA-HA screw was not associated with increased tunnel widening or cyst formation when compared with the titanium screw. The PLLA-HA screw demonstrated progressive screw resorption and gradual, but incomplete ossification over 5 years.


bioabsorbable screw, titanium screw, randomized controlled trial, 5 year follow-up



Link to Publisher Version (DOI)