Gaillard R, et al. - Survival and outcomes were compared between four total knee arthroplasty (TKA) populations defined by baseline body mass index (BMI), presuming that there would be no difference in survival between the groups. Findings demonstrated nil impact of obesity on mid-term implant survival, regardless of BMI. However, obesity did negatively affect functional outcomes and potential risk of postoperative complications.

Methods

• Researchers systematically measured BMI prior to surgery, using an initial cohort of 1059 TKAs.
• They performed a retrospective analysis and accordingly assigned allocated patients to 4 groups: normal or underweight (BMI < 25; n = 111), overweight (25 ≤ BMI < 30; n = 417), moderately obese (30 ≤ BMI < 35; n = 330) and severely or morbidly obese (BMI ≥35; n = 201).
• Thereafter, they compared the pre- and postoperative clinical and radiographical profiles of the four groups, along with any postoperative complications and the survival of each group.
• They also performed a minimum follow-up of 24 months.
• All implants had an ultra-congruent cementless posterior-stabilised rotating-platform design (Amplitude).
• Implant survival using Kaplan–Meier analysis was the primary endpoint.
• Additionally, they conducted statistical analysis using Chi-squared and Kruskal–Wallis H tests to compare the data with p < 0.05.

Results

• Researchers analyzed a total of 94 knees from normal weight or underweight individuals, 346 from overweight, 281 from moderately obese and 159 from severely or morbidly obese.
• Data reported that all knees had been operated on between 2002 and 2011 with an average follow-up of 61.7 (12–146) months.
• Findings demonstrated a significant correlation of a greater degree of obesity with young age at intervention (p < 0.001), as well as with a low average preoperative maximum flexion angle (p < 0.001) and KSS (p < 0.001).
• Researchers also found that after the operation, there were no significant differences between the groups in terms of patient satisfaction (p = 0.9) or mechanical axial deviation evaluated with whole-leg standing radiography (mFTA, p = 0.3; mFA, p = 0.1; mTA, p = 0.3).
• It was also evident that the greater the degree of obesity, the lower the average postoperative maximum flexion angle (p < 0.001), KSS knee score (p < 0.001) and function score (p = 0.005).
• The groups did not differ significantly in terms of total rate of postoperative complications (p = 0.9) or implant revision (p = 0.9), or in terms of 10-year implant survival (p = 0.4).