An orthopedic flip-wing tissue retainer (2) comprises a flip-wing (7), tissue-retaining means (8) and a joint formed between the flip-wing (7) and the tissue-retaining means (8). The tissue retainer (2) is easily installed and used to anchor a biological tissue. The tissue retainer (2) can be used in combination with other devices to replace or repair a ligament or tendon in a joint. In particular, when used for ligament replacement, the tissue retainer (2) eliminates or at least minimizes the twisting that typically occurs during conventional surgery. In addition, the tension of the ligament graft can be precisely adjusted by using a tension-adjusting device (3 or 203) in combination with the flip-wing tissue retainer (2). The tension-adjusting device (203) can include a ball (204)-and-socket (205) joint.