Correlation between subchondral bone plate thickness and cartilage degeneration in osteoarthritis of the ankle.

BACKGROUND: Osteoarthritis (OA) is characterized not only by cartilage degeneration, but also subchondral bone changes. The subchondral bone plate (SBP) plays an important role in cartilage metabolism, and elucidation of the relationship between the SBP and cartilage degeneration would be helpful to determine the most appropriate treatment strategy for ankle OA. The purpose of this study was to evaluate the SBP and to compare it with cartilage degeneration with arthroscopic findings.

METHODS: Computed tomography (CT) was used to compare the thickness of the SBP of 11 ankle OA patients with that of 11 non-ankle OA patients in 9 areas of the talar dome. The French Society of Arthroscopy (SFA) grading system was used to analyze the relationship between findings on the thickness of SBP and on articular cartilage degeneration in ankle OA.

RESULTS: The SBP in ankle OA was significantly thicker than that of the non-OA ankle. The more severe the articular cartilage degeneration, the thicker the SBP became. The SBP on the sclerotic trabecular bone was significantly thicker than that on decreased trabecular bone. The SFA grade for sclerotic subchondral bone was significantly higher than that for decreased trabecular bone.

CONCLUSION: This study shows that the thickness of SBP and the findings of subchondral bone such as decreased trabecular bone and sclerosis in CT are related to the cartilage degeneration of ankle OA, although a small number of patients were analyzed.

LEVEL OF EVIDENCE: Level III, comparative series.