Resorption characteristics of an open architecture biocomposite interference screw after ACL reconstruction

Purpose: Absorbable interference screws for anterior cruciate ligament reconstruction (ACLR) can lead to tunnel widening and cyst formation. The Biosure Regenesorb interference screw (Smith & Nephew). has been developed with an optimised calcium phosphate/polymer composition to promote bone formation during resorption. The present study aims to investigate screw resorption, new bone formation, and tunnel geometry following ACLR with Biosure Regenesorb screw tibial fixation.

Methods: The study is a prospective single-centre case series of 12 patients with ACL lesions and treated with ACLR using hamstring tendon autograft with Biosure Regenesorb interference screw tibial fixation with a two-year follow-up period. The Biosure Regenesorb consists of 65% polylactide-glycolic acid poly. 20% calcium sulphate and 15% tricalcium phosphate. Primary endpoint: Tunnel volume. implant volume and new bone formation in the tibial tunnel is evaluated by quantitative computed tomography (CT) scanning. Secondary endpoints: Arthrometric knee laxity, International Knee Documentation Committee (IKDC) and Knee Osteoarthritis and Injury Outcome Scores (KOOS) and Tegner activity scale.

Results: Screw volume decreased to 44% within the two-year follow-up period while tunnel volume remained unchanged. Only a minor amount (<1% of tunnel volume) of new bone formation in the screw remnants was observed. Sagittal knee laxity at one year was 0.9 mm. The IKDC score increased by 15 points and the KOOS sport and KOOS quality of life scores increased by 25 and 26 points. respectively.

Conclusion: ACLR using Biosure Regenesorb interference screw does not result in tunnel widening. showing a screw resorption of 44% after two years and minor new bone formation. Knee stability and subjective outcome improvements are as expected after other ACLR methods.

Level of evidence: IV.