Early tendon transplantations were confined to the foot following Nicoladoni's original operation in 1881. The knee offered the next logical site for experimentation and Goldthwait in 1897 reported on successful sartorius transplants to strengthen weak quadriceps muscles. Subsequently all the thigh muscles, individually or in combination, have been so employed.

In this end-result study we have evaluated thirty-eight patients in whom thirty-nine transplantations at the knee were done between 1922 and 1946 with an average followup of nine and two-tenths years. The subjective results were similar to those in other reports and were in general good, but on objective grounds the results were disappointing.

Knee-extension power following tendon transplantation was rated fair or better in only 30 per cent. of the cases. Seven of twelve patients using braces preoperatively were enabled to discard their braces. Even in these apparently successful cases the effect of the tendon transplantation and of other operative procedures could not be evaluated separately.

Comparison of the transplantation cases with control groups with similar patterns of muscle weakness leads us to draw certain important conclusions. The function of the extremity, as well as the ability to walk without apparatus, is dependent on a number of factors. There has been a tendency to assume that the most important factor is quadriceps or extensor power. Our study suggests that other factors are of equal importance. Good hip, posterior thigh, and calf musculature will permit excellent function, even when the quadriceps is paralyzed. On the contrary, the extremity with good quadriceps power and poor posterior musculature usually requires bracing. Good power in extension of the knee is less important in brace-free walking than is a stable foot and good posterior musculature. Tendon transplantation at the knee in some instances impairs function by the production of hyperextension deformities, dislocation of the patella, or lateral instability. Although a number of cases in this series have apparently been greatly benefited by muscle transplants, others must be rated as failure.

The indications for tendon transplantation to improve extensor power of the knee are not easy to formulate. It is our belief that in the past such operations have been done too frequently.

Poliomyelitis has been described as a subtractive disease, and ill-advised tendon transplantation at the knee in some instances is a subtractive operation.