High flexion total knee arthroplasty using short posterior flange of femoral component mid-term results

Background High-flexion designs for total knee arthroplasty were introduced and promoted greater and safer knee flexion. However, early loosening of the femoral component related to the deep flexion was reported with high incidence. Aims Contrary to conventional high-flexion designs, another femoral component was designed to allow high flexion by shortening the length of posterior condylar flange of femoral component. Authors evaluated the outcomes of high flexion total knee arthroplasty using short posterior flange of femoral component at least 3 years after the operation and to assess the occurrence of periprosthetic osteolysis and loosening. Methods Of the patients who underwent total knee arthroplasty using short posterior flange of femoral component between August 2011 and November 2014, 65 patients (94 knees) were enrolled. Knee Society Knee score, Knee Society Function score, maximal flexion angle were evaluated. Relationship between postoperative maximal flexion and radiographic factors including posterior tibial slope and femoral condylar offset was analyzed. Also, the occurrence of periprosthetic osteolysis and loosening was assessed. Results The maximal flexion was improved at the final follow-up (P<0.05). The knee score and function score were also improved after operation (P<0.05). The postoperative posterior tibial slope and femoral condylar offset showed no significant relationship with the postoperative maximal flexion angle. The periprosthetic osteolysis occurred in 3 cases but loosening did not occur at the final follow-up. Conclusion High flexion total knee arthroplasty using short posterior flange of femoral component is considered as a good alternative to conventional high-flexion prosthesis.