Microbiological vs. histological examinations in septic arthritis of the knee joint: a comparative analysis
Background: Intra-articular corticosteroid injections are frequently utilized in the conservative management of knee osteoarthritis, yet they carry a documented risk of iatrogenic septic arthritis. Despite clinical awareness of this complication, there is a significant paucity of comparative histological data regarding the specific morphological impact of steroid preparations on infected synovial and osseous tissues.
Objective: This retrospective study aims to characterize the influence of steroid preparations on tissue morphology in septic arthritis of the knee and to correlate these histological findings with microbiological culture profiles.
Key Points: A retrospective analysis was conducted on 54 patients with septic arthritis of the knee, stratified by etiology (steroid-induced versus non-steroid) and the presence of bone involvement. Microbiological results demonstrated positive cultures in 90.3% of non-steroid cases, whereas steroid-induced cases yielded positive results in only 33.3%. *Staphylococcus aureus* was the most prevalent pathogen identified (29.1%). Histological examination of surgical specimens from 12 patients revealed universal inflammatory markers, including lymphoplasmacytic infiltration, neutrophil activity, and vascular edema across all groups. However, steroid-induced infections exhibited more aggressive structural degradation. These cases were characterized by significantly reduced articular cartilage thickness and deeper destructive foci that frequently extended into the subchondral bone. The high rate of negative cultures (66.7%) in acute steroid-induced cases suggests that these preparations may initially induce aseptic cell necrosis and oxidative stress, which exacerbates subsequent infectious damage and structural failure of the joint components.
Conclusion: Steroid-induced septic arthritis is associated with accelerated cartilage and bone destruction compared to non-steroid etiologies. The observed correlation between severe morphological damage and low culture positivity suggests a complex pathophysiology involving both infectious and aseptic necrotic mechanisms.
