Article
Risk factors of Osteoarthritis: long-term follow-up after ACL transsection
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Published: | October 24, 2011 |
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Objective: Rupture of the anterior cruciate ligament (ACL) is among the most frequent sport injuries with a large socio-economic impact. In long-term, many open questions remain addressing interplay of degeneration and osteoarthritis, and instability. The aim of this study was to follow-up three cats with radiologic, kinematic, and kinetic data acquisition over a period of 12 years.
Material/Methods: Three cats underwent transsection of the anterior cruciate ligament and were followed-up for 144 months (12 years) corresponding to 68 human years. Follow-up included: 1) Radiology: conventional x-rays of the knee and radiologic documentation of the anterior drawer sign. 2) Kinematic data: cats learned to walk on the specially configured threadmill. Angles and range of motion were analyzed. 3) Kinetic data: ground reaction forces were measured with two Kistler Force plates. At the last follow-up, knee extensor forces were measured isometrically. Cats were sacrificed and knee joints underwent histologic preparation and analysis.
Results: After ACL transsection changes in gait were found. Knee joint range of motion decreases, the knee joint is held in a more flexed position while ground reactions forces reduced. These effects disappeared after 3 to 4 months and then, gait looked completely normal until to the very end, when the cats were in pain due to these advanced joint degeneration. Although gait analysis returns to normal, degeneration of the knee joint is found very early and progresses fast. Anterior drawer test remained pathologic.
Conclusion: Understanding of risk factors for joint degeneration is important in order to improve prevention of posttraumatic knee joint osteoarthritis. In this study, cats developed osteoarthritis very fast although no primary impact as a sign of acute trauma was documented. However, instability remained and must be seen as primary source for OA. Interestingly, although functional instability was compensated after 3 to 4 months, mechanical instability remained and OA progression could not be stopped.