Presidential address

For years there has been a struggle for a satisfactory intraar ticular replacement in the anterior cruciate-deficient knee. This paper summarizes our basic and clinical research over the last decade and presents a potential solution to the problem. Instron testing reveals that the anterior cruciate ligament fails at 51.2 kg. Scanning electron microscopy demonstrates that there is little difference whether the ligament is tested just to the point of failure or taken to visible rupture. The technique of the MacIntosh quadriceps-patellar tendon transfer is outlined. Two modifications in the form of a new approach through the defect in the quadriceps mechanism, as well as a new instrument to aid in the passage of the transfer are described. The strength of the tissues about the knee that have been used to substitute for the anterior cruciate ligament are pre sented. Only the distal iliotibial band seems suitable on strength characteristics alone. Intraarticular semitendinosus transfers in rabbits revealed degeneration and a marked decrease in tensile strength at 6 months. We conclude from this experiment and the data from Instron testing on autopsy specimens, substantiated by our clinical impressions, that the long-term success of autogenous intraarticular transfers seems unlikely. We introduce the ligament augmentation device (LAD) as a possible answer. A polypropylene, diamond-braided device is sutured to the prepatellar tissue in the MacIntosh repair to increase its tensile strength. It will sustain the host tissue during the period of degeneration and weakening, and thus allow eventual collagenization. We present our animal work with regard to the LAD and early human clinical application.