Lateral meniscal cysts: long-term clinical and radiological results of a partial meniscectomy and percutaneous decompressive needling

Introduction The aim of this study was to describe clinical and radiological long-term results of an arthroscopic partial meniscectomy associated with an outside-in decompressive needling of the cyst for lateral parameniscal cyst. Methods Eighteen patients with symptomatic parameniscal cysts treated between April 2002 and September 2009 were retrospectively included in the study. All patients underwent arthroscopic partial meniscectomy (preserving peripheral rim) and needling of the cyst using a 20-gauge needle. Pre- and post-operative IKDC, Tegner, and Lysholm scores were used to evaluate clinical results. Radiological results were obtained from pre- and post-operative radiographies and post-operative MRI scans. Both supine and weight bearing MRI examinations were performed. Kellgren-Lawrence and WORMS scales were used to evaluate osteoarthritis development of the knee. Results The mean follow-up period was 11.6 ± 2.6 years (range 7–15). Horizontal lesions were found in 56% of patients. All patients fully recovered. Mean Lysholm scores passed from mean pre-operative value 52 ± 16.9 to post-operative 85 ± 11.9 (P < 0.01) and mean IKDC scale score changed from 49.5 ± 14.7 to 67 ± 23.5 (P < 0.01). Mean Tegner scores did not change significantly. Post-operative radiographies showed a Kellgren-Lawrence scale grade 0 in six patients (33%), a grade I in eight (44%), a grade II in three (17%), and a grade III in one patient (6%). No patients were found with a Kellgren-Lawrence scale grade IV. No significant differences with pre-operative radiographies were found (chi-square = 1.867; df = 3; P = 0.60) in osteoarthritis development of the knee. Reported WORMS scores had an average of 12.4 ± 5.1. No recurrence of any cysts was observed. Discussion Different treatments for lateral meniscal cysts have been proposed, but proper management of the cyst is still controversial. The results of this study suggest that the outside-in needling of the cyst associated with partial meniscectomy is a highly effective, simple, and repeatable technique. Excellent clinical outcomes were reported at a mean follow-up of 11.6 ± 2.6 years (range 7–15). Imaging evaluation showed no significant evolution to osteoarthritis of the knee. Conclusions Partial arthroscopic meniscectomy associated with percutaneous decompressive needling of the cyst wall under arthroscopic visualization showed positive clinical and radiological long-term results. Neither traditional radiographies nor innovative standing MRIs showed findings of osteoarthritis.