We report three quadriceps tendon rupture and avulsion fractures of the superior pole of the patella. These cases have been operated on and exercised as soon as possible, as a result, the patients can carry out an active daily life without complications. However they result in a decrease in the circumference of the thigh, patella baja and osteoarthritic change of patellofemoral joint. Concerning these problems, we have acquired the following knowledge through extended research. The difference between the circumference of the thighs was several centimeters at early stage after surgery, but was reduced gradually and finally reduced entirely. However, in regard to the patella baja, there was no difference between the T/P ratio just after surgery and that in the long term, and no loosening of internal fixation occured. Therefore we presume that the patella baja cannot be attributed to the method of operation, the period of external fixation and rehabilitation, in addition, the osteoarthritic change of the patellofemoral joint can be attributed to the incongruence of the joint surface caused by patella baja.
