Lymphatic vessels in osteoarthritic human knees.

Area of Science:

• Orthopedics
• Immunology
• Vascular Biology

Background:

• The lymphatic system's role in knee osteoarthritis (OA) is not fully understood.
• Investigating lymphatic vessel distribution and function in OA is crucial for understanding disease mechanisms.

Purpose of the Study:

• To determine if lymphatic vessel density in knee synovium correlates with clinical, histological, or radiographic features of osteoarthritis.
• To compare lymphatic vessel density in OA patients versus non-arthritic controls.

Main Methods:

• Synovium samples from 60 OA knees and 60 control knees were analyzed using immunohistochemistry for podoplanin.
• Lymphatic vessel density (LVD) and lymphatic endothelial cell (LEC) fractional area were quantified.
• Clinical effusion, radiographic OA severity, and histological synovitis were assessed.

Main Results:

• Lymphatic vessels were found in OA and control synovium, but not in subchondral bone.
• OA synovia exhibited significantly lower LVD and LEC fractional area compared to controls.
• In OA, lower LVD was associated with clinical effusion but not with radiographic severity or histological synovitis.

Conclusions:

• Knee osteoarthritis is characterized by reduced lymphatic vessel density in the synovium.
• Impaired synovial fluid drainage due to lymphatic abnormalities may affect the interpretation of effusion as a marker of synovitis in OA.