Early Intervention of Subchondral Bone Resorption Mitigates Cartilage Degeneration in TMJOA

Excessive subchondral bone resorption is a typical manifestation in the early stage of osteoarthritis. This study is to verify whether and when intervening in subchondral bone could alleviate cartilage degeneration of temporomandibular joint osteoarthritis.

Disc displacement without reduction was used to induce temporomandibular joint osteoarthritis. Alendronate was administered subcutaneously twice a week at a dosage of 60 μg/kg body weight for 1 week by two intervention methods: early administration (1 day after disc displacement without reduction surgery) and late administration (2 weeks after disc displacement without reduction surgery). Micro-CT was used to assess subchondral bone mass and microstructure. Hematoxylin-eosin staining, toluidine blue staining, tartrate-resistant acid phosphatase staining, immunofluorescence staining, and Western blot were applied to evaluate histopathological changes of the condylar cartilage and subchondral bone.

Early alendronate administration not only prevented subchondral bone resorption in early-stage temporomandibular joint osteoarthritis, but also suppressed chondrocyte apoptosis, cartilage extracellular matrix degeneration, as well as excessive subchondral bone formation of condyle in late-stage temporomandibular joint osteoarthritis. However, late alendronate administration had little effect on either subchondral bone or cartilage degenerative changes.

Early inhibition of subchondral bone resorption could mitigate abnormal subchondral bone formation and condylar cartilage degeneration in late-stage temporomandibular joint osteoarthritis, which might be a promising strategy for temporomandibular joint osteoarthritis treatment.