Bone tunnel enlargement after anterior cruciate ligament reconstruction with the hamstring autograft and endobutton fixation technique - A clinical, radiographic and magnetic resonance imaging study with 2 years follow-up

The aim of this study was to describe the contrast-enhanced magnetic resona nce imaging (MRI) appearance of bone tunnel enlargement detected on radiogr aphy after anterior cruciate ligament (ACL) reconstruction with semitendino sus and gracilis tendon endobutton (STG-endobutton) fixation technique. Fou rteen patients with a STG-endobutton ACL reconstruction were examined 3 mon ths (n = 1), 1 year (n = 1) and 2 years (n = 12) postoperatively. An age- a nd sex-matched group with a bone-patellar tendon-bone (BTB) autograft ACL r econstruction with similar follow-up was taken as control. Data on clinical examination, laxity and isokinetic muscle torque measurements, anteroposte rior and lateral view radiography were obtained, and knee scores (Lysholm a nd Tegner)were collected. Contrast-enhanced MRT was performed in the STG-en dobutton group with a 1.5-T imager. There were no statistical differences b etween the groups with respect to clinical findings, stability tests, or kn ee scores. In the STG-endobutton group the average femoral and tibial bone tunnel diameter detected on anteroposterior view radiography had increased at 2-year follow-up by 33% and 23%, respectively. On MRI the ligamentous gr aft itself was net. enhanced by the contrast medium whereas periligamentous tissue within and around the STG graft bundles showed mild contrast enhanc ement. In conclusion, the MRI results suggest that enhancing periligamentou s tissue accumulated in and around the STG graft associated with the tunnel expansion. In spite of the significant bone tunnel enlargement observed on the follow-up radiography the STG-endobutton knees were stable and the pat ients satisfied.