Using Cumulative Load to Explain How Body Mass Index and Daily Walking Relate to Worsening Knee Cartilage Damage Over Two Years: The MOST Study

• Published in: Arthritis & rheumatology (Hoboken, N.J.) N.J.), 2020-06, Vol.72 (6), p.957-965
• Main Authors: Voinier, Dana, Neogi, Tuhina, Stefanik, Joshua J., Guermazi, Ali, Roemer, Frank W., Thoma, Louise M., Master, Hiral, Nevitt, Michael C., Lewis, Cora E., Torner, James, White, Daniel K.
• Format: Article
• Language: English
• Subjects: Accelerometers; Aged; Biomechanical Phenomena; Biomedical materials; Body mass; Body Mass Index; Body size; Cartilage; Cartilage diseases; Cartilage, Articular - diagnostic imaging; Cartilage, Articular - pathology; Confidence intervals; Damage; Disease Progression; Female; Humans; Knee; Knee Joint - diagnostic imaging; Knee Joint - pathology; Longitudinal Studies; Magnetic Resonance Imaging; Male; Mathematical analysis; Mechanical properties; Middle Aged; Osteoarthritis; Osteoarthritis, Knee - diagnostic imaging; Osteoarthritis, Knee - pathology; Osteoarthritis, Knee - physiopathology; Overloading; Patellofemoral Joint - pathology; Prospective Studies; Resonance; Risk; Statistical analysis; Time Factors; Walking; Walking - physiology; Weight-Bearing - physiology
• ISSN: 2326-5191; 2326-5205
• DOI: 10.1002/art.41181

Objective Knee cartilage damage is often linked to mechanical overloading. However, cartilage requires mechanical load to remain healthy, suggesting that underloading may be detrimental. This study was undertaken to examine knee overloading and underloading by defining cumulative load as the joint effects of body mass index (BMI) and daily walking, and examine the relationship between cumulative load and worsening cartilage damage over 2 years. Methods We used data from the Multicenter Osteoarthritis Study. Steps/day, measured by accelerometry, and BMI were calculated at the 60‐month visit. Cartilage damage on magnetic resonance imaging was semiquantitatively scored using the Whole‐Organ Magnetic Resonance Imaging Score (WORMS) at the 60‐month and 84‐month visits; worsening damage was defined as increased WORMS between visits. Risk ratios (RRs) and 95% confidence intervals (95% CIs) were calculated using binomial regression, with adjustment for potential confounders. Results Our study included 964 participants, 62% of whom were female, with a mean ± SD age of 66.9 ± 7.5 years. Participants had a mean ± SD BMI of 29.7 ± 4.8 kg/m2 and walked a mean ± SD of 7,153 ± 2,591 steps/day. Participants who walked a moderate number of steps/day (6,000–7,900) or a high number of steps/day (>7,900) and had a high BMI (>31 kg/m2) had a greater risk of worsening medial tibiofemoral (TF) damage (RR 2.83 [95% CI 1.46–5.48] and RR 2.61 [95% CI 1.50–4.54], respectively) compared with those who walked similar steps/day and had a low BMI (18–27 kg/m2). Participants with a low number of steps/day (