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COMPARISON OF THE ACCURACY OF COMPUTER ASSISTED NAVIGATED SURGERY IN ACHIEVING FINAL COMPONENT ALIGNMENT IN TOTAL KNEE ARTHROPLASTY BETWEEN SEVERE(>15) AND MILD-MODERATE.


Presenting Author - SANDEEP KUMAR REDDY
Introduction: Computer assisted surgery is well known to improve the accuracy of component placement and restoration of mechanical alignment in total knee arthroplasty. This in turn is likely to improve the long term survivorship of the components. We did a retrospective comparative study of accuracy in achieving final component alignment in varus deformities 15ᴼ(severe) Materials and Methods: Our study included 137 primary total knee arthroplasties performed between Jan and Dec 2015 using Orthopilot 5.1 B Braun Aesculap - Image free computer navigation system. We excluded 16 patients with valgus deformity, rheumatoid arthritis, hip stiffness and revision surgery. A total of 121 patients with varus deformity were included in the final study. The mean age of patients in both the groups was 64 years. All the surgeries in both groups were done by the single surgeon with Aesculap Columbus cruciate retaining design using sub-vastus approach. After registration of the bony reference points and kinematic hip ,knee, and ankle centres, medial soft tissue release and osteophyte removal, the amount of varus deformity as depicted on the navigation screen was recorded and patients were grouped accordingly into mild-moderate (Group A) and severe(Group B). Group A included 95 patients with varus 15ᴼ (mean+/-SD 18.4ᴼ+/-2.0ᴼ;range 15ᴼ-21ᴼ). With a sequential medial soft tissue release, the amount of correctable varus deformity was also recorded before the bony cuts were made. All the procedures were done by the femur first measured resection technique and the final component alignment was recorded. Postoperative full length weight bearing scannograms were taken to evaluate the FCA (Femoral component angle) and TCA (Tibial component angle) and the final mechanical alignment was calculated. Results: The final mechanical alignment was within 3ᴼ in 96.15 % of the patients in mild-moderate varus group and in 95.75 % in the severe varus group. A statistical analysis showed that this difference in the final alignment was not statistically significant (p>0.05). Conclusion: Our study shows that irrespective of the severity of deformity, with meticulous , sequential soft tissue release and using computer assisted surgery we can accurately quantify the degree of deformity, the amount of correction done and also achieve the desired, acceptable final component alignment.