Patient-reported swelling did not perform well as a proxy for magnetic resonance imaging (MRI)-identified effusion-synovitis in patients with knee osteoarthritis (OA) and meniscal tear, according to the results of a study published in Arthritis Care & Research.

Baseline data were taken from participants enrolled in the Meniscal Tear in Osteoarthritis Research (MeTeOR) trial, a randomized clinical trial of arthroscopic partial meniscectomy (APM) vs physical therapy (PT) for management of symptomatic meniscal tears. A total of 276 participants were recruited from 7 academic referral centers between June 2008 and July 2011. Patients were ≥45 years, had a non-contrast MRI of the knee with evidence of meniscal tear extending to the meniscal surface, and had at least 4 weeks of meniscal symptoms.

Demographics were collected at baseline and patient-reported swelling was assessed using a questionnaire and categorized as either no swelling, intermittent swelling, or constant swelling. Sensitivity analysis was performed to further investigate the relationship between patient-reported swelling and MRI-identified effusion-synovitis.

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Of the 276 participants, 25% reported no swelling, 40% reported intermittent swelling, and 36% reported constant swelling. Mean age was similar across swelling categories, ranging from 58 to 59 years. In addition, women comprised 69% of the participants reporting constant swelling, 51% reporting intermittent swelling, and 47% reporting no swelling. The Knee Injury and Osteoarthritis Outcome Scores, which assessed overall patient-reported pain, were greater in patients with constant swelling (54 points) compared with patients with intermittent swelling (45 points) or without swelling (38 points; P <.01).

When patients who reported any swelling, including intermittent and constant, were included in order to calculate sensitivity, specificity, and positive predictive value (PPV), swelling had a sensitivity of 84% (95%, CI 77%-89%), specificity of 34% (95% CI, 26%-43%), PPV of 57% (95% CI, 54%-61%), and positive likelihood ratio of 1.3 (95% CI, 1.1-1.5) compared with MRI-identified effusion-synovitis. After applying a more stringent cut-point of constant swelling vs intermittent and no swelling, sensitivity was 46% (95% CI, 37%-54%), specificity was 75% (95% CI, 67%-82%), PPV was 66% (95% CI, 58%-74%), and positive likelihood ratio was 1.8 (95% CI, 1.3-2.6) for effusion-synovitis on MRI.

One limitation of the study was that although effusion-synovitis identified on non-contrast MRI is frequently used as a proxy for effusion and synovitis in clinical studies, non-contrast MRI cannot be used to differentiate between effusion and synovitis. In addition, clinical assessment of effusion via physical exam was not recorded as part of the trial, and the authors could not evaluate the relationship between clinical exam evidence of effusion, MRI-identified effusion-synovitis, and patient-reported swelling. The investigators noted that this would have been useful in limiting the role of participant subjectivity. Also, the inclusion of patients with concurrent OA and meniscal tear made it difficult to discern whether OA, meniscal tear, or a combination of the two drove patient-reported swelling or effusion-synovitis as noted on MRI.

The authors advised that a firmer understanding of the association between patient-reported swelling and the presence of effusion and synovitis on imaging could help clinicians stratify patient risk. They further cautioned against using patient-reported swelling as a proxy of synovitis in patients with OA and meniscal tear.

Please see original article for a full list of disclosures.


Macfarlane LA, Yang H, Collins JE, et al. Relationship between patient-reported swelling and MRI-defined effusion-synovitis in patients with meniscus tears and knee osteoarthritis [published online May 4, 2018]. Arthritis Care Res. doi:10.1002/acr.23592