Results of Arthroscopic Treatment of Symptomatic Loss of Extension Following Anterior Cruciate Ligament Reconstruction.

Hassan SS, Saleem A, Bach BR, Bush-Joseph CA and Bojchuk J. Am J Knee Surgery. 2000;37:201-210.

This is the editor's interpretation of a paper published in the orthopaedic literature in 2000 - our attempt to make relevant medical articles accessible to lay readers. If you wish to read the original it is easy to ask your librarian to obtain a reprint for you from any medical library.

The authors of this paper followed 342 patients all having the same procedure (anterior cruciate ligament reconstruction using patellar tendon), and all procedures were performed by the same surgeon.

They found that five percent of these patients after at least four months of intensive physiotherapy had 'symptomatic extension deficits', that is they were unable to fully extend their knee and further efforts to achieve extension were painful. These patients went on to 'secondary' procedures - examination under anaesthesia (EUA), notchplasty where necessary (widening the bony notch in which the cruciates lie), surgical removal of adhesions, and controlled manipulation (MUA). After the intervention they were assigned to a closely supervised rehab protocol and the majority were followed up for several years to determine the eventual outcome.

Cause of the Extension Loss

The following were found at surgery to be contributing to the extension loss -

  • Cyclops Lesion - The surgeons found a cyclops lesion present in 8 of the 13 patients with extension loss.

    A cyclops lesion is a lump of fibrous tissue in the notch to the front of the cruciate ligaments. The common symptom of a cyclops lesion was a painless 'clunk' as the leg was straightened. In some of the patients the cyclops lesion even contained some cartilage tissue.
  • Generalised adhesions - All 13 of the patients in the study had generalised adhesions within the joint, and in all these the surgeon found it necessary to debride (cut away) scar tissue below the kneecap.

    Now, although these were not reported to be a problem in this group of patients, the authors of the paper went on to include the following also as recognised causes of inadequate extension after knee surgery
  • Incorrect tunnel placement - If the tunnel drilled in the tibia is too far forward (anterior) then the graft which passes through it will impinge on the roof of the notch, injuring the graft and stimulating the formation of a cyclops lesion.
  • Graft Hypertrophy and Inadequate Notchplasty


Outcome of Surgery

The authors report that the eventual outcome was that these patients after their secondary surgery and rehabilitation improved from a 10° extension loss to only a 3° loss, giving no functional difference from the patients who had not had any problem. They did note, however, that these patients were still left with some deficit in flexion.

They emphasise that the best management of arthrofibrosis of the knee is preventative, and they advocate careful patient selection, appropriate timing of surgery, and close attention to graft positioning and the ensuring adequacy of the notch during surgery.

However, for those patients that still go on to have an extension deficit, surgery should be undertaken to rectify any problems. In the authors' opinion this is best undertaken in the 6-12 week period after the ligament reconstruction, but patients can still have significant improvement even 8-11 months after the reconstruction.