Prognostic power of criteria for symptomatic early knee osteoarthritis from a 2-year longitudinal observation of the Iwaki cohort study

Abstract

Purpose: This study aimed to investigate whether symptomatic early knee osteoarthritis (EKOA) effectively predicts the incidence of definitive knee osteoarthritis (DKOA) in the general Japanese population. Methods: A total of 133 women from the Japanese Iwaki cohort study were enrolled and followed-up over 2 years in order to calculate the rate of progression of EKOA to DKOA. Weight-bearing anteroposterior bilateral knee radiographs and magnetic resonance imaging (MRI) were conducted at baseline and follow-up. Radiographs were classified according to the Kellgren–Lawrence grade. The presence of cartilage lesion, bone marrow lesions, attrition, cysts, osteophytes, and meniscal lesions was evaluated according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Logistic regression analyses were performed to determine the predictive power of EKOA. Results: Of 25 women with EKOA, 15 (60%) progressed to DKOA over 2 years, showing a relative risk (RR) of 1.44 compared with the non-osteoarthritis (non-OA) group (P ​= ​0.120). Logistic regression analysis showed associations of EKOA (P ​= ​0.048) and high body mass index (P ​< ​0.001) with progression to DKOA. Combined EKOA and meniscal lesions increased the RR for osteoarthritis incidence to 2.32 (P ​= ​0.004) compared with the non-OA group. Also, meniscus and bone marrow lesion scores on MRI of the EKOA group maintained high scores over 2 years. Conclusions: The prognostic power of EKOA criteria was confirmed with a RR of 1.44. The combination of symptomatic EKOA criteria and MRI-detected meniscal lesions was a valuable predictor of progression to DKOA over 2 years in women without radiographic abnormalities.

Keywords

• Longitudinal study
• Early knee osteoarthritis
• Progression
• Magnetic resonance imaging
• Meniscal lesion
• Predictive power