[New femoral fixation system for tendon transplantation in ACL reconstruction. Preliminary experience with MR...

The Authors describe the MR aspects of a new femoral fixation technique which has been recently introduced in anterior cruciate ligament recontructive surgery. This fixation device is composed of bioabsorbable material and of a thin thread which measures about 2,8 mm in diameter and 3,5 cm in length. This thread is positioned via the lateral transcondylar approach using the same arthroscopic technique as is used to position the transcondylar interference screw. By means of this technique it is possible to fix all the types of autologous grafts which are presently employed: patellar tendon, flexor tendons and quadriceps tendon. In MR, the absence of paramagnetic artifacts allows to detect also the graft portion inside the femoral bone tunnel and to acquire very accurate images.

By means of MR examination, we have studied 16 patients of either sex (11 M/ 5 F) with an age ranging from 18 to 37 years (mean age: 28,9 years). All of them underwent an anterior cruciate pro-ligament reconstruction by employing autologous tendons: the patellar tendom (=9), the quadriceps tendon (=4) and the flexor tendons (=3). By means of dedicated MR equipment at low-field intensity and with permanent magnet (Artoscan 0,2 T, Esaote, Genoa, Italy), every patient underwent follow-up controls during a period of time ranging from 1 to 9 months after the operation. We employed T1-weighted and T2-weighted spin-echo, gradient-echo and STIR sequences with fat tissue suppression. Besides the standard axial, sagittal and coronal planes, we employed a coronal plane with doubt obliquity which runs both along the axial plane and along the sagittal one with the aim of visualizing the whole graft on a single scanning plane including completely either the intra-articular portion or the bone tunnel portion.

In none of these cases we did detect para-magnetic artifacts which could prevent us from performing a complete assessment either of the fixation device or of the content of the femoral tunnel. The tendinous graft was studied along the hole intra-articular length and inside the portions of the femoral and tibial bone tunnel. For this purpose the images acquired on oblique plane along the roof of the intercondylar notch were very useful. No patient reported significant complications, apart from two cases of maniscus everlasting pain as regards medial fibrocartilaginous sutures and one case of residual pain which concerns the anterior region of the patellar tendinous donor site. The evaluation form of the International knee Document Committee shows that in clinical terms all the patients achieved good results (=7) or excellent results (=9). Overall, we detected no new grant rupture or any functional limitation of the flexor-extension.

The advent of small-size bioabsorbable synthetic materials that are compatible with the MR equipment at out disposal, make it easier to obtain a good visualization of all the portions of the anterior cruciate tendinous ligament graft. By employing suitable sequences as well as scanning planes, MR is the only technique which is able to meet any operated patient's requirements and in particular those one which concern the development state of his/her recovery progress as well as the grant-taking. Follow-up studies will be necessary, however, to determine the real evolution as well as the complete integration of these reconstructions.