Absorbable screw fixation in anterior cruciate ligament reconstruction. A clinical, MRI and CT evaluation

Absorbable (poly 1-lactic acid) interference screws were used to fix an autologous patellar tendon graft in 21 anterior cruciate ligament reconstructions. The results were evaluated clinically with the IKDC form and a KT 1000 arthrometer. CT and MRI were also carried out 3, 6 and 12 months after surgery. At follow-up after two years, the subjective assessments were normal in 5 cases, nearly normal in 12 and abnormal in 4. No cases of infection nor clinically evident reactive synovitis were observed. CT after 1 year showed that the bone plugs were completely incorporated in the bone tunnels. The gap between the screw and the plug was completely filled with bone and there was a reactive bone layer around the screw. There was no evidence of lysis at the absorbable implant site. The screws had retained their shape and there were slight signs of resorption along their outer and inner surfaces. MRI provided a more meaningful picture of the position of the tunnels and the intra-articular part of the graft. CT, on the other hand proved superior through its better demonstration of bone plug incorporation, the bone-screw interface and screw absorption.