The Gore-Tex anterior cruciate ligament prosthesis. Two versus three year results. A prospective clinical study of the results of prosthetic ligament replacement of the ACL with the Gore-Tex polytetrafluoroethylene prosthesis was undertaken. Thirty-three (80%) of 41 patients were available at a minimum 36 month followup (mean, 48 months; range, 36 to 62). Kaplan-Meier survival analysis revealed an 82% probability of survival of the polytetrafluoroethylene ligament at the 48 month followup. When compared to the same data at a minimum 24 month followup, the results appeared to have deteriorated somewhat over time. Three possible "predictors" of failure at later followup were identified: preoperative subjective symptoms of swelling, subjective symptoms of giving way at 2 years, and an increased anterior drawer sign at 2 years. 