Certain recreational, cultural, occupational, and religious practices may require knee flexion exceeding typical daily living activity needs. Some total knee prostheses mechanically accommodate high flexion to help meet such demands, e.g., the Vanguard knee (Biomet, Inc., Warsaw, IN) which can mechanically achieve 140 degrees-145 degrees. This multicenter, prospective clinical study of 957 Vanguard knees (865 patients) examined mid-term outcomes. The Kaplan-Meier survivorship estimate was 97.8% (95% CI: 96.5-98.7%) at 7.0 years. For patients with >= 2-year follow-up (n = 627), mean peak flexion increased from 116.8 degrees to 124.8 degrees (P < 0.001). For knees with pre-operative flexion of <95 degrees, 95 degrees-105 degrees, and >105 degrees, the mean increases were 27.8 degrees, 22.0 degrees, and 3.6 degrees, respectively. Mean Knee Society Knee and Function scores increased from 45.9. and 45.5 points to 92.0 and 73.8 points, respectively (P < 0.001). (C) 2014 Elsevier Inc. All rights reserved.