Combined Rotational Alignment Change after Total Knee Arthroplasty in Different Tibial Component Designs: Implications for Optimal Tibial Component Rotational Alignment

PURPOSE: The rotational alignment of the femoral and tibial components is closely related to the results after total knee arthroplasty (TKA). In this study, we measured the combined rotational alignment change (ΔCR) after TKA and compared the different influence of symmetric and asymmetric tibial component designs on the combined rotational alignment. MATERIALS AND METHODS: Eighty-four patients (mean age, 67.9 years) were included. A symmetric tibial component was used in 51 knees (group I), whereas an asymmetric tibial component was used in 50 knees (group II). We measured the angles of four anatomical landmarks by using preoperative and postoperative computed tomography images. The combined rotational alignment and the amount of change were calculated. The correlation between the isolated tibial component rotation (ITR) and ΔCR was analyzed by using the Spearman correlation coefficient. RESULTS: The mean ΔCR was −0.1°±6.3° in group I and −4.8°±5.7° in group II after TKA. Excluding the intercomponent rotation, the change was −1.0°±7.3° and −6.7°±6.7° in group I and group II, respectively. A correlation analysis between the ITR and tibial component rotation relative to the tibial tuberosity showed a statistically significant correlation. CONCLUSIONS: The combined lower limb rotational alignment was internally rotated in both symmetric and asymmetric tibial component designs after TKA. The asymmetric tibial component was better than the symmetric tibial component in achieving internally rotated combined lower limb rotational alignment. The internal rotation of the symmetric tibial component relative to the tibial tuberosity tip should fall within 20° to correct the externally deformed lower limb.

Eight to Ten Year Follow-Up Results of Total Knee Arthroplasty Using Electromagnetic Navigation System / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to compare the clinical and radiological results between patients who underwent total knee arthroplasty using the conventional method and the navigation-assisted method. MATERIALS AND METHODS: A retrospective review of was performed on 32 patients (40 knees) who underwent total knee arthroplasty between February 2004 and December 2006 and were followed-up for 8 to 10 years. Mechanical axis deviation, range of motion, radiologic position of the implants, and subjective clinical scores were measured and compared between 20 navigation-assisted total knee arthroplasties and 20 conventional total knee arthoplasties. Change in the values (α, β, γ, and δ angles) from the immediate postoperative period to the last follow-up were also calculated and compared between the two groups. RESULTS: The mean range of motion in the navigation group was improved to 121.8°±16.3° (92°–140°) at the last follow-up, and the Western Ontario McMaster Universities osteoarthritis Index (WOMAC) score was 89.8±5.4 and the Knee Society score (KSS) was 91.5±7.5. The mean range of motion in the conventional group was 112.6°±25.6° (60°–140°) at the last follow-up. The WOMAC score was 84.2±10.6, and the KSS was 81.1±14.3. The α, β, γ, and δ angles of the implants were not significantly changed until the last follow-up. In the comparison between the two groups, only the mean range of motion (p=0.018) and the KSS (p=0.038) showed statistically better results in the navigation group than the conventional group. CONCLUSION: Navigation-assisted total knee arthroplasty showed better KSS and range of motion compared with the conventional group in a cross-sectional study with 8 to 10 years of follow-up results. However, only the KSS showed a significant difference between the two groups by the amount of changes in the clinical and radiological results.