Magnetic Resonance Imaging Evaluation of Biodegradable Transfemoral Fixation Used in Anterior Cruciate Ligament Reconstruction

Purpose: The study was designed to evaluate bioabsorbable transfemoral fixation in anterior cruciate ligament (ACL) reconstruction using hamstring tendon as graft. Magnetic resonance imaging (MRI) was used to assess the continuity of the bioabsorbable implant at different stages of the patients' rehabilitation. Type of Study: Retrospective case series. Methods: Forty-nine patients underwent ACL reconstruction performed by a single surgeon. The graft, a tensioned quadrupled semitendinosus tendon, was fixed proximally using a bioabsorbable TransFix implant (Arthrex, Naples, FL). The patients underwent an accelerated rehabilitation program and were assessed clinically at regular intervals postoperatively using MRI, with specific attention focused on the implant. Results: The average time from surgery to MRI was 28 weeks (range, 4 to 54 weeks). All implants were fully visible with no evidence of resorption. Five implants were fractured at an average of 20 weeks postoperatively (range, 9 to 47 weeks). Three implants showed deformation but no definite fracture at an average of 14 weeks (range, 12 to 17 weeks). This amounts to 16% of implants with fractures or deformation, many close to the period of theoretical graft incorporation. All patients were clinically stable with no symptoms or signs or instability on clinical review and all had returned to preinjury sporting activities. Conclusions: Transfemoral biodegradable implants have the potential to fracture or deform during their postoperative course in tensioned hamstring tendon ACL reconstruction. Although no apparent detrimental effect was found in our series, further research is needed on this device before it can be recommended for ACL reconstruction. We also question the idea that rigid fixation for the ACL graft for the entire healing process is required. Level of Evidence: Level IV, retrospective case series.