Leg alignment and tibial slope after minimal invasive total knee arthroplasty: a prospective randomized radiological study of intramedullary versus extramedullary tibial instrumentation

Analysis of long leg alignment as well as tibial slope after minimal invasive total knee arthroplasty (MIS-TKA) comparing intra- and extramedullary minimal invasive surgery (MIS) tibia instrumentation (Genesis II, Smith & Nephew, Memphis, USA). A prospective randomized study was performed according to the CONSORT guidelines (n=56 patients). All measurements of alignment and tibial slope were made on standardized long leg standing X-rays as well as lateral knee X-rays performed preoperatively and 4-12 months post surgery. Long leg alignment was defined as being within or outside the range of 3 degrees varus-valgus on the mechanical axis of the leg. The tibial slope was compared pre and post surgery. Leg alignment was not significantly different after MIS-TKA with intra- or extramedullary tibial instrumentation. Restoration of the tibial slope was significantly better with use of the extramedullary tibial instrumentation.
 

This study has been presented at the ESSKA 2012 Congress (Geneva, Switzerland) and ISAKOS 2013 Congress (Toronto, Canada).