No influence of obesity on mid-term clinical, functional, and radiological results after computer-navigated total knee arthroplasty using a gap balancing technique

Abstract

Objective: In obese patients, thick subcutaneous tissue can introduce errors during registration and leg weight can influence gap balancing in navigated TKA. Present study is done to determine if computer navigated TKA using a gap balancing technique can achieve consistent accuracy for limb and component alignment, and similar clinical and functional results in obese patients like in non-obese patients. Methods: We prospectively compared the radiological, clinical, and functional results of 78 knees in 57 non-obese patients and 79 knees in 58 obese patients who underwent computer-assisted TKA. Nonobese individuals were defined as those having BMI of <30 kg/m 2 and obese individuals as BMI 30 kg/m 2 . The degree of knee deformity was calculated by Hip e Knee e Ankle (HKA) angle and clinical and functional assessment was done using the Knee Society Score e clinical knee score and Knee Society Score -function score, respectively. All these were documented before and at 6 months, 2 year, and 5 years after TKA. Results: The outlier rate of postoperative limb alignment (HKA angle) was 8.9% in the obese group which was not significantly different (p ¼1.00) from that of the non-obese group (7.7%). Mean clinical knee scores were not significantly different between the non-obese and obese groups preoperatively (58.8 vs 57.4, p ¼ 0.14) and at 6 months (92.7 vs 91, p ¼ 0.06), 2 years (91.4 vs 90, p ¼ 0.07), and 5 years (92.4 vs 91.3, p ¼ 0.1) post-surgery. Similarly, mean functional scores were not significantly different between the non-obese and obese groups preoperatively (50.9 vs 49.9, p ¼ 0.31) and at 6 months (92.7 vs 90.9, p ¼ 0.06), 2 years (91.3 vs 92, p ¼ 0.44), and 5 years (90.6 vs 91.1, p ¼ 0.51) post-surgery. Conclusion: Obesity has no influence on mid-term clinical, functional, and radiological results after computer navigated TKA, done by gap balancing technique. Level of evidence: Therapeutic level II.