Background/Purpose:  The correlates of localized knee pain (KP) and multi-site pain (MSP) have been clearly demonstrated; however, whether these factors also contribute to intermittent or persistent knee pain or MSP remains unclear. Furthermore, which peripheral structural pathology leads to persistent knee pain or MSP is yet available, there may be different mechanisms underlying their pathogenesis. Therefore, this study aimed to describe the risk factors for persistent knee pain and persistent MSP, and to investigate the associations of MRI-defined knee structural pathology with these different types of pain.

Methods:  1099 participants (mean age 63 years; range 51-81 years) from the population-based Tasmanian Older Adult Cohort study were recruited at baseline. 875, 768 and 563 participants attended years 2.6, 5.1 and 10.7 follow-up, respectively. Demographic, psychological, lifestyle and comorbidities data were obtained at baseline. T1-weighted or T2-weighted fat saturated MRI of the right knee was performed to measure knee structural pathology–cartilage defects, bone marrow lesions (BMLs) and effusion-synovitis at baseline. Presence of pain (yes/no) at the neck, back, hands, shoulders, hips, knees and feet was assessed by questionnaire at each time-point. Participants were classified as never (N), persistent (P) and intermittent (I) pain, respectively, if they had knee pain or MSP (≥2 sites) at: no assessment, four consecutive assessments from baseline with all others considered intermittent pain. Multi-nominal logistic regression was used to analyse the data with adjustment for potential confounders.

Results:  A total of 563 patients (50% female, mean BMI 27.6 kg/m²) were included. Of these, 33%, 50% and 17% were NKP, IKP and PKP, and 11%, 41% and 48% were NMSP, IMSP and PMSP, respectively. In multivariable analyses, IKP and PKP were significantly associated with baseline BMI, emotional problems, and musculoskeletal diseases. Female gender was also associated with increased odds of IMSP and PMSP. There were no associations of age, physical activity, education level, occupation and other comorbidities with either KP or MSP. Furthermore, PKP but not IKP was associated with cartilage defects (OR 2.55, 95% CI 1.38 to 4.72), BMLs (OR 1.93, 95% CI 1.07 to 3.47) and effusion-synovitis (OR 1.89, 95% CI 1.08 to 3.31) after adjustment for age, sex, BMI, other potential confounders. However, no significant associations of these lesions with IMSP or PMSP were observed.

Conclusion: Higher BMI, psychological problems and musculoskeletal diseases are associated with both intermittent and persistent KP and MSP, suggesting that factors contributing to pain may be shared in the pathogenesis of regional and generalised pain, but gender may have a different role in regional pain and generalized pain. Knee structural lesions predict PKP but not IKP, IMSP and PMSP, indicating that peripheral pathology is most important for ongoing localized pain, but it might be a trigger in contributing to generalised pain. Further research is needed to understand the underlying mechanisms of structural pathology differences in regional pain and generalised pain.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/which-factors-associate-with-localized-knee-pain-and-generalized-pain-a-10-year-longitudinal-study/