Abstract

SHETTY, GM  and  MULLAJI, A. Alignment in computer-navigated versus conventional total knee arthroplasty for valgus deformity. SA orthop. j. [online]. 2009, vol.8, n.3, pp.40-46. ISSN 2309-8309.

INTRODUCTION: Significant improvement has been reported in limb alignment and component orientation with computer-navigated total knee arthroplasty (TKA) especially in varus deformities. Literature is lacking regarding the radiographic results of navigated TKA in valgus knees. This study aims to analyse the radiographic results of navigated TKAs in valgus knees and compare them with results of our conventional technique. MATERIALS AND METHODS: We retrospectively analysed 120 primary TKAs done for valgus arthritic knees. Fifty-three computer-navigated TKAs (group N) were compared with a control group of 53 conventional TKAs (group C) for coronal and sagittal alignment of the femoral and tibial components on X-ray imaging at the end of two years after surgery. RESULTS: We found no significant difference in the postoperative coronal alignment of components between the two groups. The mean postoperative anatomic valgus angle in the group N was 5.48°±2.33° compared to 5.42° ±2.15° in group C (p=0.06). The percentage of outliers, from the acceptable range of 4° to 10° of anatomic tibiofemoral valgus, in group N was 13% (seven TKAs) compared to 17% (nine TKAs) in group C (p=0.78). Posterior femoral offset was restored more accurately in group N (p=0.047) compared to group C (p=0.68). A greater number of femoral components in group N (43%) was placed in extension relative to the distal femoral anatomic axis compared to group C (17%). CONCLUSION: Sequential soft-tissue release and computer navigation for valgus TKA gives excellent overall alignment with few outliers. The component alignment between the two groups seems to be no different except for the sagittal femoral component orientation.

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