Synovial fluid concentrations of PGE-2, CTX-I, CTX-II and COMP in the osteoarthritic temporomandibular joint compared to the knee joint

Osteoarthritis (OA) is the most prevalent chronic disorder of the
temporomandibular joint (TMJ) and is associated with significant pain and
mandibular disability. OA is a degenerative process affecting the articular
tissues. Eventually the disease leads to destruction of TMJ fibrocartilage and
subchondral bone. The TMJ is a load-bearing synovial joint, basically similar
to other load-bearing joints, although the fibrocartilage of the healthy TMJ
consists mainly of type I collagen, while most other synovial joints (like the
knee joint), contain mostly hyaline cartilage which is build up with type II
collagen.1, 2 In the affected joint, cartilage is demolished and partly
replaced. In the TMJ collagen type I is partly replaced by collagen type II and
in the knee joint the opposite seems to occur. During this process breakdown
products are formed which collect within the joint space. Due to this,
concentrations of several breakdown products change in the synovial fluid.
Since the articular cartilage is one of the first tissues to be affected by the
disease process, it is useful to measure changes in concentrations of breakdown
products of this tissue. Important markers of cartilage break-down that appear
in the synovial fluid are C-terminal telopeptide collagen type I, C-terminal
telopeptide collagen type II (CTX-I and CTX-II, respectively) and cartilage
oligomeric matrix protein (COMP).3 Furthermore prostaglandin E II (PGE-II) is a
rather specific marker for arthritis intensity.4 Measurement of these
concentrations of these substances and comparison to concentrations in the
synovial fluid of healthy TMJs could provide insight into the amount of
fibrocartilage breakdown and inflammation. Comparison of these concentrations
to the arthritic knee joint could reflect the level of agreement with
osteoarthritis in the knee. This allows an assessment of the applicability to
the TMJ of outcomes of research performed in the knee joint.

The objective of this study is to increase insight in the pathological
processes involved in TMJ OA compared to physiologic processes in healthy TMJs
and OA of the knee by determining the concentration of PGE-II, CTX-I, CTX-II
and COMP in synovial fluid of the arthritic TMJ and comparing these
concentrations with corresponding concentrations in synovial fluid of healthy
joints and synovial fluid of the arthritic knee joint.

This study is a matched case-control study.

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