Causal relationship between sarcopenia and osteoarthritis: a bi-directional two-sample mendelian randomized study

Area of Science:

• Gerontology
• Orthopedics
• Genetics

Background:

• Osteoarthritis (OA) and sarcopenia (SP) are frequently observed together.
• The causal relationship between OA and SP remains unclear.

Purpose of the Study:

• To investigate the bidirectional causal associations between sarcopenia and osteoarthritis using Mendelian randomization.

Main Methods:

• A two-sample Mendelian randomization (MR) approach was employed.
• Instrumental variables for SP (grip strength and appendicular lean mass) and four OA types (knee, hip, total knee replacement, total hip replacement) were extracted from large genome-wide association studies.
• Inverse variance weighted, MR-Egger, and weighted median estimator methods were utilized.

Main Results:

• Appendicular lean mass (ALM), a component of sarcopenia, showed a causal effect on all four types of osteoarthritis.
• Grip strength, another measure of sarcopenia, did not demonstrate a causal effect on any OA type.
• Osteoarthritis (knee and hip) did not show a significant causal effect on sarcopenia (grip strength or ALM).

Conclusions:

• Sarcopenia, specifically reduced appendicular lean mass, may causally influence the development of osteoarthritis.
• Osteoarthritis does not appear to have a causal impact on sarcopenia.
• Muscle composition, rather than muscle strength, may mediate the causal link between sarcopenia and osteoarthritis.