An investigation into damaged menisci in the average middle-aged and elderly
The menisci (plural of meniscus) are two fibrocartilaginous discs located between the femur (thigh bone) and tibia (shin bone) whose primary purpose it to provide shock absorption, handle the transfer of weight, and in turn, protect the cartilage of the knee joint. Tears to this region are extremely common, and arthroscopic partial meniscectomy, the surgery to repair tears, is the most common surgery performed by orthopedic surgeons in the country, accounting for more than 50% of surgeries performed on patients 45 years or older. For those who do undergo surgery, however, the possibility of the procedure leading to osteoarthritis of the knee (OA knee) is very strong and may lead to further complications. Though MRIs are the most common instruments used to diagnose menisci damage and determine if a meniscectomy is necessary, there is a major lack of information on meniscus tears' prevalence in the general public. Noting this, a study was conducted on general citizens in the town of Framingham, Mass., to investigate how common tears were and understand their association with OA knee.
To acquire data on potential subjects, coordinators called residents of the township aggressively to inquire if they'd be interested in partaking in a study pertaining to the status of their knees. The criteria to participate were that they must be over the age of 50 and ambulatory, though the usage of a walking-assistance device was permitted. Those with rheumatoid arthritis, dementia or terminal cancer were excluded. A total of 991 subjects were able to participate in the study, of which 57% were women, 93% were white, and the mean age was 62.3. The questionnaire asked participants specifics about pain, aching or stiffness in their right knees in the recent past. Additionally, subjects underwent an MRI scan of the knee, which was analyzed by a reader with a background in orthopedics, and also logged their height, weight and BMI (body mass index).
Findings showed that the prevalence of meniscal damage to the right knee in subjects was 35%, while more severe meniscal destruction was present in 10% of subjects. Among the 308 subjects with meniscal tears, 66% had medial (middle meniscus) tears, 24% had lateral (outer meniscus) tears and 10% had both. The commonality of tears was also found to increase with age in both sexes, as the prevalence for the 50-59 year old age group was 32% for males and 19% for females, and 56% and 51% respectively for the 70-90 year old age group. Women who had suffered one meniscus tear or more had a higher BMI than women who had not experienced a torn meniscus. The presence of meniscal tears was also higher amongst subjects who showed evidence of OA knee, and for those who showed signs of severe OA knee, 95% had meniscal damage. Shockingly, most cases of meniscal tears were found in persons who did not feel pain, stiffness or aching in their knee.
The outcome of this study elucidates that damaged menisci are overly common for average middle-aged and elder Americans, many times without knowing of the damage due to lack of symptoms. The increased use of MRIs for assessment of knee symptoms may lead to confusion, as there is a difficulty in discriminating between symptoms associated with a meniscal tear and those associated with other problems, such as OA knee. Since, as this study points out, there is a connection between meniscal tears and OA knee, reliance on MRIs becomes further complicated. Furthermore, surgical resection (removal) of damaged parts of the meniscus is unlikely to reduce pain substantially if it's actually OA that's causing it in the first place. Information regarding meniscal resection compared to nonsurgical treatment is also on the rare side. With that said, clinicians should be aware of the high number in tears and factor that into their assessment when ordering and analyzing MRIs.
-As reported in the Sept. 11 edition of The New England Journal of Medicine
