Inflammatory joint disease
Osteoarthritis is defined as a non-inflammatory arthritis. The end point of many inflammatory joint diseases left untreated is substantial joint damage. Where there is a known history of inflammatory joint disease (including septic arthritis), it is important to distinguish between joint damage caused by the inflammatory arthritis and joint damage caused by osteoarthritis. The presence of bilateral knee joint damage is more indicative of inflammation being the cause, while unilateral knee joint damage with a history of injury would imply that injury has been the primary cause. A thorough assessment of the full medical records, patient history and examination is essential in clarifying the likely cause.
Acute knee injury
Inconsistencies in reporting knee injuries demonstrate that it is important to ensure that any reported injury has been reasonably verified. There is good evidence for a clear increased risk in knee OA after specific and substantial injuries that would be identifiable at or shortly after time of injury. Where there is a history of a recorded injury identified by a suitably qualified specialist ideally with imaging or arthroscopic evidence, and subsequent development of OA in that knee alone, it would be reasonable to attribute cause to that injury.
Knee injuries with clear research-based evidence that they predispose to knee OA include anterior cruciate ligament rupture and substantial meniscus damage and meniscectomy. There is no clear evidence that partial cruciate ligament rupture or minor meniscus damage predisposes to knee OA. There is good evidence that minor meniscus pathology is increasingly common with age and does not necessarily represent a risk factor for knee symptoms or knee OA (see below under ‘meniscal injury’.
There is a significantly increased risk of knee OA following specified injuries including ligament or tendon injuries, meniscus damage or meniscectomy and fractures at or around the knee. A systematic literature search of cohort/prospective, cross-sectional and case-control studies found 24 studies for meta-analysis. There was considerable variation in risk estimates and significant gender bias attributed to men being more likely to report knee injuries sustained during occupational activities and leisure activities. The overall pooled Odds Ratio (OR) for OA after knee injury was 4.20 (95%CI 3.11-5.66, I2 = 81.0%). The OR for OA after specified injuries such as ligament or tendon injuries, meniscus damage or meniscectomy, fracture of femur, knee or lower part of leg was 5.95 (95% CI 4.57-7.75) while for unspecified injuries it was 3.12 (95% CI 2.17-4.50) (Muthuri et al., 2011).
MUTHURI, S. G., MCWILLIAMS, D. F., DOHERTY, M. & ZHANG, W. 2011. History of knee injuries and knee osteoarthritis: a meta-analysis of observational studies. Osteoarthritis Cartilage, 19, 1286-93.