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Medial and lateral discoid menisci: a case report
© Kim and Lubis; licensee BioMed Central Ltd. 2010
Received: 31 January 2010
Accepted: 23 August 2010
Published: 23 August 2010
Discoid menisci on both medial and lateral tibial plateau are very rare abnormalities. We report a 44-year-old woman with bilateral medial and lateral discoid menisci. She also had anomalous insertion of discoid medial meniscus to anterior cruciate ligament, and pathologic medial patellar plica on the right knee. Meniscectomies has been performed for her torn discoid menisci with satisfactory result on the latest follow-up.
In 1889, Young described a lateral discoid meniscus in a cadaver study , whereas medial discoid meniscus was reported at the first time by Cave and Staples in 1941 . However, up to recent years medial discoid meniscus cases were still very rarely reported. The first case of both medial and lateral discoid menisci in the same knee was reported by Jeannopolous in 1950 . Murdoch reported the first case of bilateral medial discoid menisci in 1956 [4, 5] and afterwards bilateral medial discoid menisci are extremely rarely reported [5–14]. We report a case of bilateral medial and lateral discoid menisci. The patient did well postoperatively after both medial menisci were excised in two separate operations.
On the last follow-up, seven years after the first operation and six months after the second operation, patient had no complaint and satisfied with the result. The radiological examination showed that left knee has apparent varus deformity. It could be due to the prior surgery.
Since Young reported a lateral discoid meniscus, many cases have been found. Discoid lateral meniscus is more common among Asians than that among Caucasians [15–17]. The incidence rate of discoid medial menisci reported was from 0.03% to 0.3% [6, 11]. By using MRI, it is now possible to diagnose meniscus condition noninvasively . Blacksin et al.  described the first case of bilateral discoid medial menisci diagnosed using MRI. Yanez-Acevedo reported a case of bilateral discoid lateral menisci and unilateral discoid medial menisci, thus three discoid menisci in an 11-year-old girl .
Dickason has reported the large series of 10 medial discoid menisci in which there was one 22-year-old man with bilateral massive discoid menisci . The incidence of discoid menisci is difficult to be estimated since the rate of asymptomatic patients is high. Yaniv and Blumberg cited that the incidence of discoid meniscus ranges from 0.4% to 17% for the lateral and 0.06% to 0.3% for the medial side.
Lateral discoid menisci with symptomatic tears are well-known lesions that are usually thought to affect mostly children and adolescent [7, 20]. It is also not common for a discoid meniscus to become symptomatic and present with a tear in adulthood [6, 7]. However, in the series of Dickason et al., 62% of the patients were older than 18 years of age . Akgun et al. reported bilateral discoid medial menisci in an adult patient .
Some papers reported bone changes with discoid medial meniscus [8, 21]. Atay et al. , reported the increased concavity of the medial tibial plateau of their bilateral discoid menisci case, and decreased signal intensity of the subchondral medial tibial epiphysis consistent with reactive sclerosis. Weiner et al. , reported depression of the medial tibial plateau followed by complete reformation of the depressed medial tibial plateau after meniscectomy. In our case, we found bilateral increased concavity of the medial tibial plateau, more clearly in the right side, and sclerotic of the right medial tibial plateau on anteroposterior and lateral radiological examination.
Patel believes that the discoid meniscus should be preserved if "severe symptoms are not present" . The technique used in the management included a careful resection of the menisci back to firm, longitudinal fibers . Senior author has described arthroscopic one-piece excision technique for the treatment of symptomatic lateral discoid meniscus .
The result depends on the amount of retained meniscal tissue, the associated lesions, the activity level of the individual, and the length of the follow-up . In general, the results of meniscectomy for discoid meniscus are good. Our patient also had no complain and she has satisfactory with the result of both of her surgeries. However a longer follow-up period is still needed since discoid meniscus has been reported as one of the risk factors for articular cartilage lesions [24, 25]. The duration of symptoms and meniscal shape showed significant relation with articular cartilage lesion .
Written informed consent was obtained from the patient for publication this case report and the images.
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