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Computer-assisted total knee arthroplasty leads to better restoration of leg alignment and component orientation compared with the conventional technique.
Total knee arthroplasty (TKA) is a reliable treatment option for primary and secondary osteoarthritis with satisfactory results in >82% of patients.1 However, aseptic loosening and knee instability remain the most causes of TKA failure and an overall 10year revision rate of 15%.2
Malalignment of the mechanical limb axis after TKA is one important factor affecting patient outcome and resulting in prosthetic loosening. In previous studies, a postoperative limb axis within ±3° varus/valgus was associated wim a lower rate of aseptic prosthesis loosening.38 Although various mechanical alignment guides have been designed to improve alignment accuracy in TKA, postoperative malalignment of me mechanical limb axis remains a serious problem. Petersen and Engh9 reported me radiographic results of 50 primary TKAs implanted using the conventional technique. In their study, 26% of TKAs failed to achieve a satisfactory postoperative limb alignment of ±3° varus/valgus. In another study,10 the radiographic results of 673 TKAs were analyzed, and a mechanical limb axis of > ±3° varus/valgus was reported in 25% of cases.
Recently, navigation systems have been developed to improve tiie accuracy of component alignment in TKA and the first follow-up results of computer-assisted TKA are promising. Mielke et al1 ' compared the radiographic results after computer-assisted surgery with Üiose of me conventional implantation technique. They found a tendency for better alignment of me mechanical limb axis in computer-assisted TKA. However, in a second study by Jenny and Boeri,12 no significant differences in the postoperative mechanical leg axis were noted between the computerassisted and conventional technique.
This prospective study analyzed the accuracy of component orientation and postoperative leg alignment in computer-assisted TKA and compared these results with me conventional technique.
MATERIALS AND METHODS
Study Design and Patients
Primary TKA was performed on 100 consecutive patients with knee osteoarthritis using a computer-assisted CT-free navigation system or the conventional technique. Preoperatively, no exclusions were defined regarding age, gender, degree of leg axis deviation, or previous surgeries. The same prosthesis model (PFC Sigma; Depuy Ine, Warsaw, Ind) was implanted in all cases, and patients underwent prospective follow-up. The study was approved by the local ethic committee.
Patients in both groups were comparable regarding...