Knee Injuries and Knee Osteoarthritis: A Meta-analysis
History of knee injuries and knee osteoarthritis: a meta-analysis of observational studies
Muthuri SG, McWilliams DF, Doherty M, Zhang W. OA Cartilage. 2011. 19(11):1286-93.
It has been suggested for years that knee injuries are a risk factor for developing knee osteoarthritis (OA). Unfortunately, most studies are inconsistent in how previous knee injuries are defined (e.g., type of injury, severity of injury) and this has made it challenging to accurately determine the true risk of developing knee OA after sustaining an injury. Therefore, Muthuri et al performed a meta-analysis of 24 observational studies to quantify the association between knee OA and history of knee injury. Unfortunately, 14 (58%) of the studies did not provide a detailed definition of knee injuries. Most studies relied on participants reporting a history of injury but 3 studies verified a knee injury with magnetic resonance (MR) imaging or hospital records. Overall, participants with a history of knee injury were 4.2 times more likely to have knee OA. Men and women with a history of knee injuries were 5.8 and 2.6 times more likely to have knee OA, respectively, than members of the same sex with no history of knee injury. Furthermore, the odds for knee OA among males with a history of knee injury (compared to those without a history of knee injury) were higher than the odds among females with a history of knee injuries (compared to those without a history of knee injury). Unfortunately, not enough studies specified the site or severity of injury to determine how these variables influence the odds of developing OA. There is some evidence that the type and severity of injury may be important. For example, four studies that defined injuries based on MR imaging of meniscal damage or self-reported meniscectomy showed a high risk of developing OA (odds ratio = 6.9; significantly above the overall odds for knee OA reported earlier).
This study is significant because it verifies that knee injuries are a risk factor for developing knee OA and it highlights some key questions that need to be answered. Interestingly, gender may be an influential factor in predicting the risk of knee OA among individuals with a history of knee injury but is unclear if it is a factor causing the greater risk among males or an indirect assessment of other physical or psychosocial variables. Future research will need to determine if injury type and severity as well as gender are key determinates for the risk of developing knee OA. Furthermore, it is important to clarify if injuries early in life increase the risk of developing knee OA more than injuries later in life. It would also be interesting to see how follow-up time influenced the results because longer follow-up after injuries may provide more time for OA to be detected. Ideally, some of these questions should be addressed in prospective studies that would allow us to accurately record the type and severity of injury, confirm that absence of OA at the time of injury, and the time it takes for OA to be detected. Several studies are currently monitoring patients with anterior cruciate ligament injuries but it will also be important to monitor healthy athletic controls change over time. In the meantime, this study demonstrates that a history of knee injury is a strong risk factor for the development of knee OA and as the authors note “knee injuries may be prevented…which implies that more initiatives aimed at reducing injuries…could be beneficial in reducing the risk of future knee OA.” This study highlights the need for more research from the sports medicine community as well as the importance for us to further develop and implement injury prevention programs. Has your clinical site started to use injury prevention programs?
Written by: Jeffrey Driban
Reviewed by: Stephen Thomas
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