Suture debris from high-tensile sutures contributes significantly to particle-induced tissue response in shoulder arthroplasty.

Abstract

Background and hypothesis: Polyethylene wear debris has long been known to be important for the development of osteolysis and aseptic loosening in total joint replacements. Evaluation of shoulder hemiarthroplasty (HA) specimens provided a unique opportunity to study the histopathologic response when a polyethylene-bearing surface was absent. We hypothesized that HAs would exhibit no significant inflammatory periprosthetic tissue response due to the absence of significant numbers of wear particles from the articulation.

Methods: We analyzed 13 shoulder HAs. The explants were examined for damage to the bearing surface and taper damage using a stereo-microscope. The periprosthetic tissues were examined histologically for wear debris and cellular biological response. Fourier Transform Infrared Spectroscopic imaging (FTIR-I) and scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) were used to characterize debris, if present, within tissue samples.

Results: The average patient age at the time of implantation was 57.2 ± 7.3 and the average time in situ was 34.1 ± 29.4 months. The metal-bearing surface damage was primarily mild, with an average score of 1.5±0.7. The same was true for taper damage on both humeral stem and head tapers, with average scores of 1.7±0.5 and 1.7±0.9, respectively. The histopathological analysis revealed the considerable presence of metal debris in 11 (91.7%), cement debris in 4 (33.3%), and suture debris in 11 (83.3%) cases. SEM/EDS revealed titanium alloy debris to be the most dominant type of metal particle present, while FTIR-I scans suggested polyester to be the most commonly occurring type of suture debris. Particles were mostly found within and around macrophages. The mean macrophage score was 3.1 ± 0.8 and the mean foreign-body giant cell (FBGC) score was 2.3±1.1. There was, on average, no significant lymphocyte or neutrophil presence, except for a single septic case.

Discussion and conclusion: This surgically retrieved shoulder HA cohort exhibited a considerable macrophage and FBGC response within the periprosthetic environment. Interestingly, given the low amount of damage to metallic surfaces and the absence of a polyethylene bearing, the tissue response does not appear to be driven by wear particles from the metal-bearing surface or taper junctions but rather from suture and, to a much lesser degree, cement and metal debris. Overall, these findings highlight the potential impact that high-tensile suture material, frequently used in high quantities around shoulder arthroplasty, may have on the periprosthetic environment and identify these materials as a potential driver of osteolysis.