Specific material effects of wear-particle-induced inflammation and osteolysis at the bone-implant interface: A rat model.

INTRODUCTION: Wear particles produced from prosthetic joints may play critical roles in periprosthetic inflammatory reactions and osteolysis. The objective of this study was to quantify and compare the response to wear debris from different biomaterials at the bone-implant interface in a rat knee model. METHODS: Sixty rats were divided into titanium alloy (Ti-6Al-4V), cobalt chromium (Co-Cr), ceramic (Al2O3), ultrahigh molecular weight polyethylene (UHMWPE), and control (phosphate buffered saline) groups with 12 animals per group. A nonweight-bearing titanium rod was implanted into the right distal femur of each rat followed by intra-articular injections of the biomaterial particles to the surgical knees for up to 16 weeks. Micro-computed tomography scanning was performed monthly and at the time of sacrifice to determine bone densities around the bone-implant interface. Histological evaluations were executed to quantify local inflammatory reactions and osteoclastogenesis. RESULTS: Co-Cr particles resulted in the most severe reductions in bone density. UHMWPE and ceramic particles resulted in a rapid reduction in bone density followed by a recovery. Inflammatory pseudo-membranes were ubiquitously present close to the femoral condyle and pin insertion site. Ceramic particles significantly promoted periprosthetic tissue formation compared with the other groups (p < 0.05). Cathepsin K positive cells were dominantly present at the peri-implant site following challenges of metallic alloy and ceramic particles. CONCLUSION: Different biomaterials in particulate form exert different forms of adverse effects in terms of the amount of osteolysis and inflammatory reactions on bone tissue at the bone-implant interface. It provides information for engineering more appropriate materials for arthroplasty components.

Proximal Row Carpectomy.

Proximal row carpectomy (PRC) has earned a respected place in the hand surgeon's armamentarium. Prerequisites for the standard PRC are good cartilage on the proximal pole of capitate and in the lunate fossa of radius. If there is cartilage damage on the proximal pole of capitate, the modification of Salomon and Eaton is a reasonable alternative to the standard PRC. The most important surgical step is preservation of the radioscaphocapitate ligament. Good long-term results can be achieved, and with careful patient selection the operation can be done successfully in people who use their hands for heavy work.

MOLECULAR SYSTEMATICS OF THE GENUS NEOTOMA BASED ON DNA SEQUENCES FROM INTRON 2 OF THE ALCOHOL DEHYDROGENASE GENE.

Phylogenetic relationships were evaluated among 13 species of Neotoma based on DNA sequences from intron 2 of the nuclear alcohol dehydrogenase gene 1 (Adh1-I2). Sequences were analyzed using parsimony, likelihood, and Bayesian methods. Three major clades (I-III) consistently were recovered and relationships among taxa within 2 of the clades remained unchanged between analyses; however, relationships within clade III were largely unresolved. Average genetic divergence values were 2.12% among species, 4% between subgenera (Teonoma and Neotoma), and 5.1% between genera (Hodomys and Neotoma). Adh1-I2 sequences were concatenated with mitochondrial cytochrome-b sequences generated from the same individuals. Examination of the combined data resulted in a phylogeny whose topology was similar to that based only on cytochrome-b sequences.