Subjective evaluation of the UCBL polycentric knee linkage by active above knee amputees. A prospective trial.

In this study 20 active male above knee amputees were fitted with prostheses incorporating prototype UCBL four-bar polycentric knee units. The subjective responses of the amputees were evaluated in a prospective fashion. Additional information concerning the short-term durability and mechanical behavior of the device is presented. The average followup was 12.3 months. Sixteen of the 20 subjects felt that they benefited from the device, and seven of these stated that the research prosthesis was superior to all previous devices that they had used. Four subjects stated that they had received little or no benefit from the research limb. Previous levels of function and the ease of performance of specific activities were maintained or enhanced in almost all subjects. Most subjects felt that the ease of walking on inclines was improved, and found the increase in knee flexion afforded by the mechanism to be an advantage. Early in the study, problems were encountered due to air leaks in the pneumatic swing-phase control units and to excessive wear of the aluminum linkage pins. These problems were corrected easily, and the devices were found to function well during the remainder of the study. Given the encouraging results from this preliminary clinical trial, we conclude that further study and clinical application of the UCBL four-bar polycentric knee are indicated.