Early results with the Genesis II Posterior Stabilized High Flexion knee prosthesis. A one year follow-up study

The aim of this prospective study was to assess the range of motion (ROM) achieved with the Genesis II Posterior Stabilized High Flexion knee prosthesis. The ROM was compared with that of a historical study group with the standard PS insert and an identical study design. Sixty three patients with primary knee osteoarthritis (37 female, 26 male; average age: 67.0 years, average BMI 31.2) underwent primary cemented TKA with a PS high flex insert. The surgery was performed by one senior author using a mini-midvastus approach. During the follow-up no statistically significant difference in maximal flexion was found between 14 weeks (average flexion = 120 degrees, SD = 11.2) and 65 weeks postoperatively (average flexion = 122 degrees, SD = 8.9). The radiographic evaluation showed no influence of the implant positioning on the final flexion. Compared to the results obtained in a 5 year follow-up study of 100 cases in combination with the PS standard insert, the improvement in final flexion range found in this study did not appear not to be great enough to generally recommend the PS high flex insert in terms of a proven higher flexion result.