RESUMEN
BACKGROUND: Whether the arterial tourniquet in total knee arthroplasty (TKA) is a friend or a foe is still debated. Longer ischemia causes hypoxic damage; yet short duration of a tourniquet may influence outcome. Understanding the time-dependent influence of the tourniquet in TKA patients could improve the overall outcome and safety. The purpose of the study was to measure the tourniquet-induced time-dependent alterations in skeletal muscle metabolism in TKA to establish a 'safe tourniquet time.' METHODS: In the femoral quadriceps muscle of 12 patients undergoing a total knee arthroplasty with a tourniquet (TKA) we measured the ischemic response using microdialysis. Lactate, pyruvate, glucose and glycerol were measured in the muscle underneath the tourniquet, in the ischemic muscle distally to the tourniquet and in the opposite muscle as a reference. RESULTS: Lactate pyruvate ratio (L/P ratio) increased time-dependently after 15min of ischemia. L/P ratio increased faster underneath the tourniquet compared to ischemic tissue distal to the tourniquet. Glycerol was elevated underneath the tourniquet compared to ischemic tissue distal to the tourniquet and correlated to the individual ischemic response. Only minor increases in creatine-kinase, asparagine-aminotransferase, and lactate-dehydrogenase were observed. Thirty minutes of reperfusion normalized lactate levels. CONCLUSIONS: The muscle underneath the tourniquet suffered more from ischemia than the ischemic tissue distal to the tourniquet. Less than 15min of ischemia did not increase ischemic markers. If any muscle damage occurs from longer tourniquet time, it is likely reversible and occurs mainly underneath the tourniquet. Fifteen minutes of ischemia appears safe.
Asunto(s)
Artroplastia de Reemplazo de Rodilla , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/metabolismo , Torniquetes , Anciano , Asparagina/metabolismo , Creatina Quinasa/metabolismo , Femenino , Glucosa/metabolismo , Glicerol/metabolismo , Humanos , Isquemia/diagnóstico , Isquemia/metabolismo , L-Lactato Deshidrogenasa/metabolismo , Ácido Láctico/metabolismo , Masculino , Microdiálisis , Persona de Mediana Edad , Estudios Prospectivos , Ácido Pirúvico/metabolismo , Factores de Tiempo , Transaminasas/metabolismoRESUMEN
Partial knee arthroplasty (PKA) has shown obvious advantages compared to total knee arthroplasty, but survival of PKA from different institutions and registries has differed. In our institution, 695 consecutive Oxford medial PKAs were performed from 2002 to 2011 with mean follow-up of 4.6 years. The overall 10.7-year survival rate was 85.3% (95% CI: 78.7%-90.0%), and no difference in survival for gender and age younger or older than 60 years was found. One year after PKA, 94.3% were very satisfied or satisfied, as were 93.6% six years postoperatively. The revision rate was 7.3% (n=51), and the most common causes for revision were progression of osteoarthritis (n=16), aseptic loosening (n=11), and pain without loosening (n=10). Only 50% of patients revised for pain without loosening had a satisfactory outcome.
