Early results of high-flex total knee arthroplasty: comparison study at 1 year after surgery.

We compared clinical [including maximal flexion and range of motion (ROM)] and radiographical outcomes of high-flex versus conventional implants for total knee arthroplasty (TKA) after 1 year. We also analyzed the factors affecting postoperative ROM in high-flex implants. The high-flex group (n=90) had an average maximal flexion of 129.8 degrees (standard deviation (SD), 5.2 degrees ) significantly higher than the 124.3 degrees (SD, 9.2 degrees ) of the conventional group (n=90), especially for patients with less than 90 degrees of knee flexion (P<0.05). There was no significant difference in hospital for special surgery (HSS) score between the two groups. No knee developed osteolysis, aseptic loosening, or other complications. We found that, for high-flex implants, preoperative ROM had a significant effect on postoperative ROM.