The relationship between longitudinal serum leptin measures and measures of magnetic resonance imaging-assessed knee joint damage in a population of mid-life women

Abstract

Background and objective: Serum leptin measures are associated with radiographic knee osteoarthritis, but no studies have examined leptin levels with respect to different measures of knee joint damage from MRI.

Methods: Participants in the Michigan Study of Women's Health Across the Nation underwent bilateral knee MRIs at follow-up visit 11 for assessment of cartilage defects, bone marrow lesions, osteophytes, meniscal tears, synovitis and joint effusion. Serum leptin measures were available from baseline, follow-up visits 1 and 3-7.

Results: Baseline serum leptin levels were associated with greater odds of having more severe knee joint damage at follow-up visit 11 after adjustment for age, smoking status, menopause status and body mass index residuals. The greatest effect was observed for osteophytes; a 5 ng/ml increase in baseline leptin was associated with 24% higher odds of having larger osteophytes (95% CI 1.17 to 1.32). Correlations with baseline serum leptin were greatest for MRI-assessed osteophytes (r=0.41), followed by effusion (r=0.32), synovitis (r=0.30), cartilage defects (r=0.28), bone marrow lesions (r=0.24) and meniscal abnormalities (r=0.21).

Conclusions: Leptin levels 10 years prior to MRI assessment were associated with the presence of cartilage defects, bone marrow lesions, osteophytes, meniscal tears, synovitis and effusion among a population of middle-aged women. Understanding the role that leptin plays in the joint degradation process is critical for development of more targeted interventions for osteoarthritis.

Keywords: Epidemiology; Knee Osteoarthritis; Osteoarthritis.

Figure 1

Predicted Trajectories of Serum Leptin (ng/mL) by Magnetic Resonance Imaging-Defined Knee Cartilage Defects at Follow-Up Visit 11 Among Michigan Study of Women’s Health Across the Nation (SWAN) Participants. Brown Line Represents Women With No Cartilage Defects (Signal Alteration Only); Green Line Represents Women With Cartilage Defects < 50% Thickness; Red Line Represents Women With Cartilage Defects 50–99% Thickness; Blue Line Represents Women With Cartilage Defects 100% Thickness.

Figure 2

Predicted Trajectories of Serum Leptin (ng/mL) by Magnetic Resonance Imaging-Defined Knee Osteophytes at Follow-Up Visit 11 Among Michigan Study of Women’s Health Across the Nation (SWAN) Participants. Brown Line Represents Women With No Osteophytes; Green Line Represents Women With Osteophytes ≤ 5 mm; Red Line Represents Women With Osteophytes 5–10 mm; Blue Line Represents Women With Osteophytes > 10 mm.

Figure 3

Predicted Trajectories of Serum Leptin (ng/mL) by Magnetic Resonance Imaging-Defined Knee Synovitis at Follow-Up Visit 11 Among Michigan Study of Women’s Health Across the Nation (SWAN) Participants. Green Line Represents Women With No Synovitis; Red Line Represents Women With Mild Synovitis; Blue Line Represents Women With Moderate-Marked Synovitis.