4The role of biomechanics in the initiation and progression of OA of the knee
Section snippets
Functional anatomy of the knee
The knee is the largest and one of the most complex joints. It comprises three distinct functional compartments: the patellofemoral joint, which consists of the patella and the patellar sulcus on the ventral femur, and the medial and lateral tibiofemoral compartments articulating the femur with the tibia (Fig. 2a and b). The articular cartilage on the joint surfaces supports low-friction motion and wear-resistant load transfer.
The two menisci are semicircular fibrocartilage structures located
Knee alignment
Knee alignment is often easy to measure but highly complex to fully understand in the causal chain of events in knee OA. Little is known about the contributing factors to altered alignment during the natural course of OA, although meniscal extrusion and maceration together with cartilage morphology are among the probable candidates [10]. Several measurements of alignment can be obtained using different techniques, for example, static hip–knee–ankle alignment measured on long leg films; anatomic
Meniscal injury
The treatment of meniscal injury has an interesting history that well illustrates the biomechanical problem the loss of meniscal function inflicts. In 1883, a British surgeon first successfully sutured a torn medial meniscus [17], but, 4 years later, he published yet another report, where he justified total removal of the meniscus rather than repair, and that view would prevail for over 80 years [18]. Already, in the late 1940s, Fairbank speculated that frequent radiographic changes found after
Anterior cruciate ligament injury
In contrast to meniscal injury, which normally does not give noticeable instability symptoms, the ACL injury may cause mechanical instability and reduced knee confidence in persons with a high activity level. The long-term consequences are also problematic. The reported risks of developing radiographic OA after ACL injury vary between 10% and 90% at 10–20 years after the ACL injury, the high variability mainly due to differences in study design [48]. However, considering that acute injury often
Occupational load and obesity
In epidemiological studies, heavy physical activity is associated with a higher risk of developing knee OA [53], *[54], [55], [56]. This may be due to a higher risk of joint injury in highly active individuals. However, excessive repetitive joint use appears to be associated with OA as well. Certain occupational kneeling has also been associated with increased frequency of knee OA, providing yet another evidence of the important role of biomechanics [57]. Interestingly, in parallel
Acknowledgements
I would like to thank Dr Ida K Haugen for helpful inputs to this article.
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