Knee osteoarthritis (OA) is a prevalent condition among the aging population. A common diagnostic tool used to diagnose OA is MRI. Much of the medical profession, however, is aware that image findings are infrequently associated to clinical findings and symptom presentation. Recently, a systematic review and Meta-analysis was published in the British Journal of Sports Medicine to provide summary estimates of the prevalence of MRI features of OA in asymptomatic individuals.
Using the PRISMA guidelines, a systematic review of the literature was conducted with the aim of identifying studies that reported prevalence of MRI features of OA in asymptomatic individuals. It is important to recognize that the current definition of MRI-defined knee OA is: cartilage defects defined as full or partial thickness lesions, meniscal tears defined as high signal extending to an articular surface, bone marrow lesions defined as areas of ill-delineated signal within trabecular bone, and osteophytes defined as the presence of osseocartilaginous protrusions at articular margins.
Table 1 displays the findings of the study with regards to each MRI finding for pooled and age stratified data. As you can clearly see, prevalence of lesions at the knee on MRI are relatively common among asymptomatic individuals, in particular those over the age of 40.
Table 1. Prevalence of MRI Findings.
| MRI Findings | Pooled Data | <40 yoa | >40 yoa |
| Cartilage defects | 24% | 11% | 43% |
| Meniscal tears | 4% | 19% | |
| Bone Marrow Lesions | 18% | 14% | 20% |
| Osteophytes | 25% | 8% | 37% |
The authors suggest that management of OA related features in atraumatic knee pain should be centered around improving symptoms and functional limitations as opposed to being driven by imaging findings. The authors also speculate that the high frequency of imaging findings in asymptomatic individuals might serve as an explanation with regards to why surgical management and arthroscopy have limited efficacy.
One take home for this paper is that the use of MRI imaging is not valuable in determining or diagnosing atraumatic knee pain. Similarly, previously acquired images should not be used to inform a diagnosis or treatment plan in the absence of clinical findings. Another take home for this paper is that patients who are considering undergoing surgical procedures for MRI or image related findings might be better served using a trial of conservative care first, given the high likelihood that the findings are asymptomatic.
References
- Culvenor AG, Øiestad BE, Hart HF, Stefanik JJ, Guermazi A, Crossley KM. Prevalence of knee osteoarthritis features on magnetic resonance imaging in asymptomatic uninjured adults: a systematic review and meta-analysis. British journal of sports medicine. 2019 Oct 1;53(20):1268-78.