Association of MRI-derived muscle-fat composition with knee osteoarthritis severity: a gender-stratified X-ray and MRI correlation study.

Background: Knee osteoarthritis (OA) is a common musculoskeletal disorder characterized by the progressive degradation of articular cartilage, along with changes in surrounding soft tissues and bone structures. The knee joint is particularly susceptible to osteoarthritic changes, resulting in pain, functional impairment, and a significant decline in the quality of life for affected individuals. Plain radiography and MRI are considered the standards imaging modalities for diagnosis. Aim: This research aims to explore the correlation between soft tissue changes and the severity of knee OA, utilizing both traditional plain radiographs and advanced MRI techniques. The study also focuses on gender differences to provide insights into potential modifiable risk factors and therapeutic targets. Methods: A total of 232 patients underwent knee MRI and X-ray imaging for various clinical indications. Radiographs were classified according to the Kellgren-Lawrence scale, while MR images were used to assess body composition and degenerative changes in the knee. Results: Among the 232 participants, 54.7% were female and 45.3% were male, with most aged 30-44 years and categorized as obese (44.8%). The data revealed that muscle thickness remained consistent across BMI categories, with males generally exhibiting higher values than females. Fat thickness increased with higher BMI categories, with females consistently showing greater values than males. The muscle-to-fat ratio decreased as BMI increased, with males having higher ratio in the normal BMI category compared to females. Pearson's correlation indicated that muscle to fat ratio has a weak negative correlation with soft tissue degenerative changes, and cartilage degenerative changes. Cohen's Kappa coefficient analysis revealed fair agreement between binary classifications derived from X-ray and MRI findings. The McNemar's test indicated a statistically significant difference in detection capabilities between the two techniques. Conclusion: The muscle-to-fat ratio and fat thickness significantly impact knee degenerative changes, particularly in females. This underscores the necessity for targeted interventions aimed at reducing fat thickness while preserving muscle thickness to enhance overall health outcomes. Although X-rays exhibit higher sensitivity, they have lower specificity compared to MRI; both diagnostic methods improve in accuracy as disease severity increases. The combination of MRI and X-ray further enhances the diagnostic accuracy for knee OA.