Does Obesity Affect Clinical and Radiological Outcomes in Minimally Invasive Total Knee Arthroplasty? Minimum 5-Year Follow-up of Minimally Invasive TKA in Obese Patients

BACKGROUND: The aim of this study was to evaluate the clinical and radiological outcomes of minimally invasive total knee arthroplasty (MIS-TKA) in obese patients. METHODS: We examined the records of 371 cases of MIS-TKA performed using the mini-midvastus approach from January 2006 to December 2006. According to body mass index (BMI), the cases were classified into group A (BMI < 25 kg/m(2), 114 knees), group B (25 kg/m(2) ≤ BMI < 30 kg/m(2), 179 knees), and group C (BMI ≥ 30 kg/m(2), 78 knees). Clinical outcomes were measured with the Hospital for Special Surgery Score and Knee Society Score. Radiological evaluation included measurements of knee alignment. RESULTS: MIS-TKA was performed on all patients. The skin incision size in group A, group B, and group C was 8.2 ± 0.8 cm, 8.3 ± 0.8 cm, and 8.5 ± 0.9 cm, respectively, and the operation time was 86.4 ± 10.4 minutes, 85.9 ± 11.3 minutes, and 89.0 ± 11.4 minutes, respectively, indicating no significant difference among the groups (p > 0.05). There was no difference in terms of the accuracy of the tibial implant alignment, with 97.6%, 95.2%, and 93.4% of each group showing 90° ± 3° varus angulation (p > 0.05). With respect to the accuracy of the femorotibial angle, 93.9%, 94.6%, and 90.2% of each group had 6° ± 3° valgus angulation, with group C demonstrating the lowest level of accuracy (p < 0.05). The preoperative range of motion and Knee Society Score of group C were less than those of groups A and B (p < 0.05), but there was no notable difference among groups at the postoperative 3-month and 1-year follow-ups (p > 0.05). CONCLUSIONS: MIS-TKA in obese patients showed satisfactory clinical and radiological results without significant difference in surgical results compared to nonobese patients.