| dc.description.abstract | Total knee arthroplasty (TKA) is an effective procedure which relieves pain, restores knee function, and improves the quality of life of patients with end stage knee arthritis [1-6]. Further improvement of its results seems difficult. Ten year survival rates are reported to be higher than 90 % in large patient series and registers [7]. Total knee arthroplasty outcomes are highly dependent on surgical technique, specifically limb alignment, and implant positioning. Proper alignment of the femoral and tibial components is an important predictor of postoperative pain, polyethylene liner wear, stability, and implant longevity [8-11]. Implant malposition is also associated with postoperative pain, decreased function and/or higher revision rates. More than 50 % of TKA revisions are performed within 2 years after surgery and a common reason is component malposition [12]. In addition, when TKA is performed in lower volume hospitals (hospital volume of 25-50 TKAs/year), a higher TKA revision rate at 5-8 years has been reported. Numerous studies have demonstrated that poor clinical outcomes and decreased implant longevity in TKA are often associated with inaccurate placement of either the tibial or the femoral implant [9, 13-18]. Choong et al. [19] found that more accurate component placement correlates with better knee function and improved quality of life. Some investigators have reported that even in major arthroplasty centers, optimal postoperative alignment of the components can only be obtained in 70-80 % of patients using conventional techniques with either intra or extramedullary alignment rods. Computer assisted navigation techniques, including image based and image free systems, have been recently developed and used in order to improve the positioning of the components and the axis of the limb in TKAs performed for both deformed and normally aligned knees [20-25]. Effective soft tissue balancing is also a determinant of TKA long term outcome [15, 26]. Common reason for TKA failure is patella component or extensor mechanism failure in combination with femoral and tibial components, alignment failure [18, 27, 28]. In cases with extraarticular femoral deformities, it is difficult to perform distal femoral cuts using intramedullary alignment rods and instrumentation for extramedullary alignment is not reliable in the coronal and sagittal planes. Instead, computer assisted navigation can help surgeons to perform TKA in such difficult cases [29]. © Springer-Verlag London 2015. | en |
