Abstract: An interlocking strap to immobilize a human leg in a flexed position so as to permit surgery upon the knee. The strap is releasably secured to one part of the limb and, thereafter, the limb is secured and maintained in the flexed position by releasably securing the strap to a second part of the limb. The strap comprises an elongate portion of web material having two cooperative strips of fastening material sewn on its opposing major surfaces. The fastening material is curly pile loop and hook-type, self-gripping strip fasteners sold under the trademark VELCRO with the respective hook and loop strips mounted on respective faces of the overlapping strap portions to be fastened together around the parts of the flexed limb.