Inflammatory reactions in primary osteoarthritis of the hip and total hip prosthesis loosening

In 14 patients [9 with loosened total hip arthroplasty (THA), 5 with primary osteoarthritis], the inflammatory cell infiltrate was characterized in cryostat tissue sections using antibodies against subsets of macrophages and lymphocytes. In all patients the abundance of a mature type macrophage (25F9+) was observed, whereas 27E10+ macrophages, characteristic of acute inflammatory reactions, were not seen in primary osteoarthritis but were found in 4 out of 9 patients with THA loosening. The RM3/1 + macrophage phenotype was seen in some of both sets of patients (osteoarthritis 4/5; THA loosening 4/9). The markers MRP8 and MRP14 typical of immature macrophages, were found in all patients with osteoarthritis and in some (4/9 and 8/9 respectively) of those with THA loosening. IOT4+ T-helper cells were only present in 1/5 5 patients with osteoarthritis and in 2/9 patients with THA loosening. IOT8+ T-suppressor lymphocytes were more frequently present (in 4/5 and 5/9 respectively). The data reveal remarkable differences between the two groups of patients. While the inflammatory infiltrate in patients with osteoarthritis lacks the characteristics of acute inflammation, in patients THA loosening the inflammatory process seems to be determined by periods of acute reactions. The occasional presence particularly of T-helper cells suggests that the inflammatory process is less T-cell but rather macrophage-driven.