Publication:

A radiological evaluation of loop length change in adjustable versus fixed loop femoral cortical fixation devices in arthroscopic anterior cruciate ligament reconstruction: a prospective study

Background In anterior cruciate ligament reconstructions, fixed devices require over-drilling to flip the button whereas loops of adjustable devices can be adjusted intraoperatively, and they minimize over-drilling. But they can loosen rendering the reconstruction incompetent. Most studies comparing them are bio-mechanical studies. Our aim was to record and compare loop length change radiologically in adjustable versus fixed devices in clinical settings.

Methods 32 patients were divided into 2 groups of 16 patients each. Hamstring graft were prepared. It was loaded in the suspension device and the apex of the graft was marked using silicon vascular radio-opaque marker. In adjustable devices, lengthening was checked after cycling and re-tensioning was done intra-operatively. Post-surgery, digital X-ray of the knee was taken in true antero-posterior and lateral view. Distance between the centre point of the button and the centre-point of the radio-opaque inert silicon marker was recorded at immediate post-operative and at 6 weeks respectively and compared.

Results 15 patients in each group were incorporated. Intra-operatively, loop lengthening was seen in all 15 patients with adjustable loop and re-tensioning was done. 2 of the 15 cases showed evidence of radiological loop lengthening however in both cases the lengthening was less than 3 mm and thus was not significant.

Conclusions We in in vivo radiology based clinical study did not find any significant loop lengthening in patients with adjustable loop devices. Hence fixed and adjustable loop devices are comparable.