Prevalence of bilateral Discoid Lateral Menisci (DLM) in patients operated for symptomatic DLM with a follow-up study on their asymptomatic contralateral knees: a Magnetic Resonance Imaging (MRI) assessment.

BACKGROUND: The purpose was to investigate prevalence of bilateral discoid lateral menisci (DLM) in Han Chinese patients who received surgery for symptomatic DLM, as well as a follow-up study of their asymptomatic contralateral knees using magnetic resonance imaging (MRI). METHODS: A total of 110 patients [50 males and 60 females; average age: 21.95 ± 12.77 years (range: 6 to 67 years)] admitted to our hospital with symptomatic DLM were treated with arthroscopic surgery. The contralateral asymptomatic knees were evaluated for DLM by MRI. Postoperative clinical evaluation was performed using the Lysholm knee scoring scale and International Knee Documentation Committee subjective knee evaluation. RESULTS: Eighty (72.73%) of 110 symptomatic DLM patients had bilateral DLM, of which 68 (85%) were of homotype (same type). Fourteen of 80 bilateral DLM patients were symptomatic and received operations in both knees. Twelve of remaining 66 bilateral DLM patients with asymptomatic one knee underwent a second arthroscopic surgery as their asymptomatic knees became symptomatic over the five-year interim. Of these 12 cases, seven exhibited no shift and five showed posterocentral meniscal shift. Furthermore, at least two cases showed progression from asymptomatic grade II to symptomatic grade III over the interim. All patients showed significant improvement after surgery. CONCLUSIONS: The bilateral DLM rate of Han Chinese patients with symptomatic DLM was relatively high at 72.7 %, and 85 % of those were of homotype.

Incidence of bilateral discoid lateral meniscus in an Asian population: an arthroscopic assessment of contralateral knees.

PURPOSE: To investigate the incidence of bilateral discoid lateral meniscus (DLM) and to evaluate the arthroscopic features of lateral meniscus in asymptomatic contralateral knees in an Asian population who presented with symptomatic DLMs. METHODS: This study prospectively enrolled 52 consecutive patients who underwent arthroscopic procedures for symptomatic DLMs (31 complete and 21 incomplete) and who consented to the examination of the contralateral knee at the time of arthroscopy. Types of DLMs and of meniscus tears were assessed by use of arthroscopic findings. Preoperative and postoperative functional outcomes were evaluated with Lysholm and Tegner activity scores. RESULTS: Arthroscopic examinations showed 21 complete DLMs, 19 incomplete DLMs, 11 normal lateral menisci, and 1 ring-shaped lateral meniscus in contralateral knees. The incidence of bilateral DLM in our study population was 79% (41 of 52 contralateral knees). Furthermore, 65% of patients (34 pairs of knees) had the same DLM types. In addition, 3 pairs of knees with complete DLMs had menisci of different thicknesses. DLM tears were observed in 2 contralateral knees (1 radial and 1 longitudinal) and were treated by partial central meniscectomy. CONCLUSIONS: This study provides evidence of the high prevalence of bilateral DLM in an Asian population.

Clinical, radiologic and arthroscopic assessment and treatment of bilateral discoid lateral meniscus.

The purpose of the study is to evaluate clinical, radiologic and arthroscopic features of bilateral discoid lateral meniscus and to assess the outcome of arthroscopic meniscectomy. Among the 177 arthroscopies performed for discoid lateral meniscus between January 1993 and January 2004, 12 were bilateral. The clinical and radiologic evaluation was done from the records. The type of discoid meniscus, the type of tear was assessed arthroscopically. All patients underwent arthroscopic meniscectomy. Patients were followed up for a minimum period of 2 years. All patients had pain as presenting symptom. Eight patients presented with bilateral knee pain and four patients developed pain in the opposite knee after the affected knee was treated. The classically described thud was present in 11 knees. The widening of the joint space was found in 13 knee radiographs; 14 knees had complete type, nine had incomplete type and one had ring type of discoid lateral meniscus on arthroscopic evaluation; 20 knees involving 10 complete types, all incomplete types and ring type of discoid lateral meniscus showed obvious meniscal tears. The remaining four meniscus showed softening of a portion of the meniscus. Underlying intra-substance tear was visualized arthroscopically in the softened areas on saucerisation. All but one discoid menisci underwent arthroscopic partial central meniscectomy. When followed up for an average period of 32.6 months 19 knees showed excellent results and 5 knees good results. Possibility of bilaterality should be suspected in discoid lateral meniscus. Softening of meniscus denotes underlying intra-substance tear. This finding has not been described in the literature so far. Arthroscopic partial meniscectomy gives good results in symptomatic bilateral discoid meniscus. This to our knowledge is the largest series of bilateral discoid lateral menisci.