Adiscoid meniscus, found in 1%-5% of the population, .is a human anatomic variant that usually affects thelateral meniscus of the knee. A discoid meniscus is more prone to injury than a normally shaped meniscus. In 19...Adiscoid meniscus, found in 1%-5% of the population, .is a human anatomic variant that usually affects thelateral meniscus of the knee. A discoid meniscus is more prone to injury than a normally shaped meniscus. In 1941,1 Cave and Staples first reported discoid medial meniscus. A bilateral discoid medial meniscus is extremely rare. The first case of bilateral discoid medial meniscus was reported by Murdoch in 1956.2 Since then, no more than 20 case reports of bilateral discoid medial menisci have been published to date, and most have been single case reports.3 Treatment of a torn discoid medial meniscus is similar to the treatment of a tom lateral meniscus of the knee. In cases where there is a significant disability, surgical excision may be required. Traditionally, the treatment of choice for symptomatic torn discoid meniscus has been open total or partial meniscectomy. Currently, arthroscopic partial meniscectomy is commonly used. Either meniscectomy or conservative method for treatment of a discoid medial meniscus with no tear is a debatable issue.3 A 39-year-old male was admitted to our hospital for intermittent swelling and pain of his right knee in 1999. He had a history of twisting injury on the affected knee 10 years before the admission, but the symptoms were not significant at that time. However, one year ago, on and off swelling with pain had gradually developed in his right knee, worsening with long distance walking and sports activities. Sometimes he felt that the knee was ＂giving way＂. Due to increasing discomfort interfering with his daily life, he was referred to us by his doctor. Physical examination of the patient＇s right knee showed atrophy of the musculus quadriceps femoris compared to the opposite side, medial tibiofemoral joint line tenderness, a range of motion from , and positive McMurray sign. The patient had no complaints on his opposite knee and physical examination did not reveal any abnormalities. MRI scan showed discoid medial meniscus with a horizontal cleavage tear while lateral meniscus appeared normal （Figure IA, B）. On 16th August 1999, arthroscopic examination of the right knee confirmed the presence of a complete discoid medial meniscus with horizontal cleavage and longitudinal tears and a normal lateral meniscus, while the tom discoid medial meniscus was reshaped by arthrotomy partial meniscectomy. The patient has been followed up for12 years, and the treatment outcome has been good and satisfactory to date. In 2011, the same patient was admitted again for intermittent swelling, pain and locking of his left knee. The patient experienced symptoms for 6 months with no previous history of injury. Physical examination of the left knee showed effusion of （＋＋） in the joint, atrophy of the musculus quadriceps femoris, medial tibiofemoral joint line tenderness, restriction of mobility, range of motion , and positive McMurray sign. MRI showed discoid medial meniscus with a horizontal cleavage in mid-body and posterior horn while the lateral meniscus appeared normal （Figure 1C, D）. Arthroscopic surgery was performed on 20th July 2011. Upon arthroscopic observation, discoid medial meniscus in the left knee was found to be the complete type with a horizontal cleavage in mid-body and longitudinal tears near the peripheral rim, but the lateral meniscus was normal. Discoid medial meniscus was reshaped by partial meniscectomy, using arthroscopic techniques （Figure 1E, F）. Discoid meniscus is found in 1%-5% of the population, with a slightly higher incidence in Asians. Discoid meniscus is an uncommon finding that typically affects the lateral meniscus of the knee, and the involvement of the medial meniscus bilaterally is extremely rare. A retrospective study was conducted by Dickason and colleagues in 1982,4 in which 8040 cases of medial menisci were analyzed. Among them, 10 were discoid menisci （0.12%）, and only one had bilateral involvement （0.012%）. Several studies on findings of bilateral discoid medial menisci have been reported by Asian doctors in recent years.3 To date, as few as 20 cases of bilateral discoid medial menisci have been reported. Interestingly, in the present case, the symptoms of the two knees appeared 12 years apart. We have confirmed the diagnosis of complete discoid medial menisci with tearing in the right knee in 1999 and the left knee in 2011.展开更多
文摘Adiscoid meniscus, found in 1%-5% of the population, .is a human anatomic variant that usually affects thelateral meniscus of the knee. A discoid meniscus is more prone to injury than a normally shaped meniscus. In 1941,1 Cave and Staples first reported discoid medial meniscus. A bilateral discoid medial meniscus is extremely rare. The first case of bilateral discoid medial meniscus was reported by Murdoch in 1956.2 Since then, no more than 20 case reports of bilateral discoid medial menisci have been published to date, and most have been single case reports.3 Treatment of a torn discoid medial meniscus is similar to the treatment of a tom lateral meniscus of the knee. In cases where there is a significant disability, surgical excision may be required. Traditionally, the treatment of choice for symptomatic torn discoid meniscus has been open total or partial meniscectomy. Currently, arthroscopic partial meniscectomy is commonly used. Either meniscectomy or conservative method for treatment of a discoid medial meniscus with no tear is a debatable issue.3 A 39-year-old male was admitted to our hospital for intermittent swelling and pain of his right knee in 1999. He had a history of twisting injury on the affected knee 10 years before the admission, but the symptoms were not significant at that time. However, one year ago, on and off swelling with pain had gradually developed in his right knee, worsening with long distance walking and sports activities. Sometimes he felt that the knee was ＂giving way＂. Due to increasing discomfort interfering with his daily life, he was referred to us by his doctor. Physical examination of the patient＇s right knee showed atrophy of the musculus quadriceps femoris compared to the opposite side, medial tibiofemoral joint line tenderness, a range of motion from , and positive McMurray sign. The patient had no complaints on his opposite knee and physical examination did not reveal any abnormalities. MRI scan showed discoid medial meniscus with a horizontal cleavage tear while lateral meniscus appeared normal （Figure IA, B）. On 16th August 1999, arthroscopic examination of the right knee confirmed the presence of a complete discoid medial meniscus with horizontal cleavage and longitudinal tears and a normal lateral meniscus, while the tom discoid medial meniscus was reshaped by arthrotomy partial meniscectomy. The patient has been followed up for12 years, and the treatment outcome has been good and satisfactory to date. In 2011, the same patient was admitted again for intermittent swelling, pain and locking of his left knee. The patient experienced symptoms for 6 months with no previous history of injury. Physical examination of the left knee showed effusion of （＋＋） in the joint, atrophy of the musculus quadriceps femoris, medial tibiofemoral joint line tenderness, restriction of mobility, range of motion , and positive McMurray sign. MRI showed discoid medial meniscus with a horizontal cleavage in mid-body and posterior horn while the lateral meniscus appeared normal （Figure 1C, D）. Arthroscopic surgery was performed on 20th July 2011. Upon arthroscopic observation, discoid medial meniscus in the left knee was found to be the complete type with a horizontal cleavage in mid-body and longitudinal tears near the peripheral rim, but the lateral meniscus was normal. Discoid medial meniscus was reshaped by partial meniscectomy, using arthroscopic techniques （Figure 1E, F）. Discoid meniscus is found in 1%-5% of the population, with a slightly higher incidence in Asians. Discoid meniscus is an uncommon finding that typically affects the lateral meniscus of the knee, and the involvement of the medial meniscus bilaterally is extremely rare. A retrospective study was conducted by Dickason and colleagues in 1982,4 in which 8040 cases of medial menisci were analyzed. Among them, 10 were discoid menisci （0.12%）, and only one had bilateral involvement （0.012%）. Several studies on findings of bilateral discoid medial menisci have been reported by Asian doctors in recent years.3 To date, as few as 20 cases of bilateral discoid medial menisci have been reported. Interestingly, in the present case, the symptoms of the two knees appeared 12 years apart. We have confirmed the diagnosis of complete discoid medial menisci with tearing in the right knee in 1999 and the left knee in 2011.
