Figs. 1-A and 1-B A case of patellar impingement and distal patellar calcification. LP = length of the patella, HI = height of the insertion, LT = length of the tendon, ISR = Insall-Salvati ratio, and PTR = patellar tendon insertion ratio.

Fig. 1-A.

Lateral knee radiograph made two months after the femoral replacement.

Fig. 1-B.

At three years postoperatively, the patient presented with a distal patellar spur with impingement on the tibial component. Despite the impingement, the range of motion was 0° to 120°, and anterior knee pain was mild (Grade I).