Degenerative changes of the interface membrane as a possible reason for prosthesis loosening

Objective: The aim of the present study was to perform a comparative evaluation of septic and aseptic interface membranes, assessing histological features, inflammatory infiltrate, and expression of inflammatory cytokines. Methods: Septic and aseptic interface membranes from 102 patients were examined by histology, histochemistry, and immunohistochemistry (tissue arrays). The cell subpopulations were characterized by quantification of CD3, CD4, CD8, CD20, and CD163 positive cells. Additionally, a semiquantitative evaluation of inflammatory cytokines (TNFa, TGF-ß1, IL-1, IL-6, CRP, MMP-1, MMP-6) was performed to complete the analysis of inflammatory infiltrates. Results: The histological analysis revealed three different types of aseptic interface membranes: wear particle, degenerative, and mixed type. The expression of inflammatory molecules did not differ between septic and wear particle interface membranes. Significantly lower expression of cytokines, MMPs and CRP was observed, however, in degenerative interface membranes compared to other types. No expression of TNFa was observed in the degenerative interface membranes. Over 88% of patients with degenerative interface membranes had had a clinical record of osteoarthritis. Conclusion: Aseptic interface membranes were represented by wear particle, degenerative and mixed type. The expression of inflammatory factors in wear particle type is similar to this in septic membranes and can contribute to the bone destruction and prosthesis loosening. These factors seem not to play a major role in the degenerative membranes

Morphologic and histologic comparison between the patella and hamstring tendons grafts: A descriptive and Anatomic study

Purpose: Morphologic and histologic comparison of patella and hamstring tendon grafts. Methods: Hamstring tendons (semitendinosus and gracilis) and patellar tendons were taken from 20 cadaveric knees and were investigated by using light and electron microscopy, immunohistochemistry, and morphometry. The thickness of collagen fibrils, fibril/interstitum ratio, density of blood vessels, density of fibroblasts, and distribution of the collagen fibrils were analyzed. Results: The sernitendinosus and gracilis tendons provide 20% and 30% more fibril/interstitum ratio compared with the patella tendon (P =.0056 and .0028). Also, the density of fibroblasts was 50% and 35% more (P =.0061 and .0050). No differences regarding the thickness of the collagen fibrils, density of blood vessels, and distribution of the fibrils were found. Conclusions: Both semitendinous and gracilis tendons provide significantly more density of collagen fibrils as well as density of fibroblasts in comparison with patellar tendons. These findings provide a potential advantage of the hamstrings group on better remodelling and regeneration of the tissue. Clinical Relevance: These grafts have been used as autografts for anterior cruciate ligament reconstruction. Despite the interest on these tendons, their microscopic structure has not been sufficiently investigated yet