Functional outcomes and complications of patients contaminated with Cutibacterium acnes during primary reverse shoulder arthroplasty: study at two- and five-years of follow-up.

PURPOSE: The objective of the study was to compare the functional outcomes and the complication rate of the patients with C. acnes contamination at the end of the primary reverse shoulder arthroplasty (RSA) surgery to those patients without C. acnes contamination. METHOD: A total of 162 patients were included. In all cases, skin and deep tissue cultures were obtained. A molecular typing characterization of the C. acnes strains was performed. Functional outcomes were assessed with the Constant score at the two and five year follow-up and all complications were also recorded. RESULTS: A total of 1380 cultures were obtained from the 162 primary RSA surgeries. Of those, 96 turned out to be positive for C. acnes. There were 25 patients with positive cultures for C. acnes. The overall postoperative Constant score was not significantly different between those patients having C. acnes-positive cultures and those with negative cultures at the two and five year follow-up (59.2 vs. 59.6 at two years, p 0.870, and 59.5 vs. 62.4 at five years, p 0.360). Patients with positive cultures presented a higher complication rate (p 0.001) with two infections, one revision surgery, and one dislocation. CONCLUSION: Patients ending up with C. acnes-positive cultures after primary shoulder arthroplasty surgery do not have worse clinical outcomes when compared to patients having negative cultures, but a greater number of complications were found in those patients with C. acnes-positive cultures.

Polyethylene particles in joint fluid and osteolysis in revision total knee arthroplasty.

BACKGROUND: One of the most frequent reasons for total knee arthroplasty late failure is osteolysis. It has been related to foreign body reaction to polyethylene particles. The aim of this study is to analyse the number, size and morphology of polyethylene particles in synovial fluid in total knee arthroplasty revision and correlate them to the pathology and the degree of osteolysis. METHODS: Synovial fluid was obtained in 12 patients before the revision total knee arthroplasty. Polyethylene particles were isolated and analysed through scanning electron microscopy. Samples of synovial tissue were analysed with optical microscopy while considering the parameters of particles and histiocytic infiltration. Osteolysis was analysed with plain radiography and the macroscopic aspect during surgery. RESULTS: The statistical analysis showed a significant correlation between a high concentration of polyethylene particles in synovial fluid and a high degree of osteolysis. The concentration of particles in synovial fluid also showed a significant correlation with a high degree of particles and histiocytes in the histological analysis. There was a relationship between the size of particles and the degree of osteolysis. No relationship was found between the shape of the particles and the histological findings or the degree of osteolysis. CONCLUSIONS: In an "in vivo" TKA scenario, the presence of a high concentration of polyethylene particles in the synovial fluid seems to be the cause of a highly active foreign body histological reaction, with an increased number of histiocytes, which seems to be the cause of a significant degree of osteolysis around the implant.