The presence of bone marrow lesions and cartilage defects on baseline MRI scans of knee osteoarthritis (OA) patients may help to predict moderate to severe pain trajectories, based on data from a population-based study presented here at the European Congress of Rheumatology.
Three pain trajectories were identified: 52% of the patients reported stable mild pain over time, 33% reported moderate pain over time, and 15% reported fluctuating or severe pain over time.
Dr. Feng Pan
“Knee pain is the most prominent symptom of knee osteoarthritis,” Dr. Pan said in an interview. “It is also a main reason for people to seek joint replacement. Despite this, the causes of knee pain are poorly understood. Therapy will only improve if we understand this better.”
Dr. Pan and his colleagues studied 1,099 adults with knee OA who participated in a population-based study. The mean age was 63 years (ranging from 51 to 81 years). A total of 875 participants were assessed using the knee pain components of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 2.6 years’ follow-up, 768 at 5.1 years’ follow-up, and 563 at 10.7 years’ follow-up.
Knee OA was assessed at baseline by x-ray, and T1-weighted or T2-weighted MRI scans of the right knee were used to assess knee structural pathology. The researchers applied group-based trajectory modeling to identify pain trajectories.
“We identified three distinct trajectories over time,” Dr. Pan said. “Remarkably, structural, environmental, sociodemographic, and psychological factors are associated with a more ‘severe pain’ trajectory, suggesting that pain course is determined by an integrated mix of all these factors.”
Dr. Pan added: “We already know that structural damage is a major driver in the development and maintenance of pain severity, but less is known about the other factors.”
The researchers found a significant dose-response relationship between the number of knee structural abnormalities, including cartilage defects and bone marrow lesions, and the ‘moderate pain’ and ‘severe pain’ trajectories (P less than .001 comparing both categories to the ‘mild pain’ trajectory).
Other factors that were significantly associated with both moderate and severe pain, compared with mild pain, included higher body mass index (overweight but not obese), emotional problems, and musculoskeletal diseases.
The findings provide support to the concept that “pain experience is both complex and individual in nature, suggesting the clinician should target treatments according to which of these factors predominate in the individual,” Dr. Pan said.
Future research may aim to develop “a predictive model that could be utilized in clinical practice and target therapies based on these trajectories.”
Dr. Pan had no financial conflicts to disclose.