Purpose: There is some controversy over the most appropriate management of knee dislocation. Following the 1995 SOFCOT symposium, the most promising results appeared to be obtained with emergency treatment using a synthetic reinforcement. The purpose of this prospective work was to validate this conclusion.

Material and methods: Between November 1994 and October 1998, 17 patients admitted for emergency care of a knee dislocation were included in this prospective study. Ten were men, mean age was 29 years (17–48). A complete work-up was acquired: plain radiographs with stress views, MRI in 14 patients. The central pivot was torn in all cases. Tears involved the lateral ligaments in eleven cases, the medial ligaments in six and the patellar tendon in one. There were no vessel lesions. One patient had popliteal sciatic nerve paralysis. Emergency surgery was performed to staple or suture the peripheral tissues and suture the posterior cruciate ligament plus a synthetic reinforcement (Ligastric); the anterior cruciate ligament was not repaired. Immediate rehabilitation started with mobilisation 0°/60°up to day 21 then with 0°/90° up to day 60. The lower limb was immobilised in an extension brace and weight-bearing was encouraged starting on day 60.

Results: All patients were reviewed at consultation with stress radiographs. Mean follow-up was three years (two to six years). The IKDC score was recorded. Four patients had arthrolysis, one had an isolated reconstruction of the anterior cruciate ligament, one had an ablation of the synthetic ligament and repair of the anterior cruciate ligament. The 70° posterior drawer was 18° preoperatively and 9 mm at last follow-up (21–0 mm). The greatest laxity corresponded to a patient who had had ablation of the synthetic ligament. The Pudda index was 6 mm, mean mobility was 0/130°, and two patients had asymmetric 10° recurvtum. Subjective outcome was very satisfactory for seven patients, satisfactory for nine and disappointing for one.

Conclusion: The objective result can still be improved by correcting the posterior laxity. Not repairing the anterior cruciate ligament immediately does not worsen prognosis. There were no complications related to the synthetic ligament. This therapeutic attitude can be proposed for major knee trauma.

Purpose: Radiologists describe cysts of the anterior cruciate ligament (ACL) as a cystic formation of the cruciate tentorium. The estimated prevalence is 0.2 to 1.3% of patients explored by magnetic resonance imaging. The purpose of this study was to better define the clinical symptoms involved by comparing clinical, radiological and pathological findings.

Material and methods: Between February 1996 and April 2000, nine men underwent surgery of the anterior cruciate ligament for cysts. Mean age at surgery was 43 years (26) 54). None of the patients had a history of trauma and one patient had undergone medial meniscectomy 12 months earlier due to meniscosis. Pain had been present for six months to seven years and progressed slowly. It was very specifically related to hyperflexion. Five patients exhibited a moderate effusion and five had a painful joint line. The Lachmann was stiff. Single leg stance plain x-rays were normal. Magnetic resonance imaging demonstrated a poorly delimited heterogeneous destructured aspect of the ACL in seven patients. The suggested diagnosis was “partial tear of the ACL or old tear of the ACL”. A perfectly circumscribed cyst was revealed by the MRI in two cases, lying behind the ACL in the tentorium of the notch. The posterior cruciate ligament had a normal aspect in all cases.

Results: All patients underwent arthroscopy. The ACL was deorganised, widened and yellow in eight, with a yellow circumscribed nodule on the posterior aspect in one. An impingement between the ACL and the tentorium of the notch was observed in one case. Total synovectomy of the ACL sheath removing part of the ligamentous fibres was performed in eight cases. An isolated cyst was removed in one. Plasty of the notch was performed in one. Pathology reported degenerative dystrophic lesions in eight cases and haemopigmented villonodulary synovitis in one. All patients were reviewed at a mean follow-up of 14 months (8–48). Pain at hyperflexion had completely subsided and there was no hydrarthrosis. The Lachmann was stiff and symmetrical.

Conclusion: The term ACL cyst is probably inappropriate because we were unable to find true cystic formations but rather a spontaneous degenerative process. Synovectomy of the sheath gave good clinical results. MRI findings can be a diagnostic pitfall: a destructured aspect of the ACL without a context of trauma should suggest spontaneous degeneration of the anterior cruciate ligament.