Seudotumor infectado en un paciente con artroplastia de cadera con par de fricción metal-metal

La artroplastia total de cadera es el principal tratamiento para la artrosis avanzada de cadera y las complicaciones pueden ser luxación, infección, aflojamiento aséptico y, en menor medida, reacciones adversas al metal. El seudotumor es una complicación poco frecuente con un par de fricción metal-metal. El diagnóstico y el tratamiento correctos son muy importantes para disminuir la morbimortalidad. Presentamos el caso de un hombre de 63 años que había sido sometido a una artroplastia total de cadera con un par de fricción metal-metal, 13 años atrás. Al consultar, tenía una gran masa en el glúteo derecho y parestesias en el territorio ciático homolateral. Se diagnosticó seudotumor asociado a infección periprotésica y el tratamiento definitivo consistió en revisión en un tiempo y la administración de antibióticos

Cartilage immunoprivilege depends on donor source and lesion location

The ability to repair damaged cartilage is a major goal of musculoskeletal tissue engineering. Allogeneic (same species, different individual) or xenogeneic (different species) sources can provide an attractive source of chondrocytes for cartilage tissue engineering, since autologous (same individual) cells are scarce. Immune rejection of non-autologous hyaline articular cartilage has seldom been considered due to the popular notion of “cartilage immunoprivilege.” The objective of this study was to determine the suitability of allogeneic and xenogeneic engineered neocartilage tissue for cartilage repair. To address this, scaffold-free tissue engineered articular cartilage of syngeneic (same genetic background), allogeneic, and xenogeneic origin were implanted into two different locations of the rabbit knee (n=3 per group/location). Xenogeneic engineered cartilage and control xenogeneic chondral explants provoked profound innate inflammatory and adaptive cellular responses, regardless of transplant location. Cytological quantification of immune cells showed that, while allogeneic neocartilage elicited an immune response in the patella, negligible responses were observed when implanted into the trochlea; instead the responses were comparable to microfracture-treated empty defect controls. Allogeneic neocartilage survived within the trochlea implant site and demonstrated graft integration into the underlying bone. In conclusion, the knee joint cartilage does not represent an immune privileged site, strongly rejecting xenogeneic but not allogeneic chondrocytes in a location-dependent fashion. This difference in location-dependent survival of allogeneic tissue may be associated with proximity to the synovium

To resurface or not to resurface the patella in total knee arthroplasty

The management of the patellar articular surface at the time of primary total knee arthroplasty (TKA) is controversial. We used expected-value decision analysis to determine whether the patella should be resurfaced in TKA, and also whether secondary resurfacing on an unresurfaced patella is worthwhile. Outcome probabilities and utility values were derived from randomized controlled trials only. A decision tree was constructed and fold-back analysis was performed to ascertain the best treatment path. Sensitivity analyses were performed to determine the effect on decision-making of varying outcome probabilities and utilities. Our model showed patellar resurfacing is the best management strategy for the patella at the time of primary TKA. This decision is robust to changes in the specific data: the best path would remain the same as long as the incidence of persistent anterior knee pain (AKP) with resurfacing remains less than 29% (current mean, 12%) or the incidence of AKP after nonresurfacing falls below 12% (current mean, 26%). Delayed (ie, secondary) patellar resurfacing for ongoing patellar pain provides inferior results for the majority of patients. LEVEL OF EVIDENCE: Level II, decision analysis. See the Guidelines for Authors for a complete description of levels of evidence