An intraoperative leg stabilizing system has a platform with a slidable brace received in a longitudinal groove. The slidable brace supports the patient's foot. The platform also has an outrigger that pivots about a base in the platform. The outrigger can pivot up to a desired orientation. The longitudinal position of the slidable brace and the orientation of the outrigger can be fixed through locking mechanisms. The system includes a support belt that can be wrapped around the patient's thigh and then connected to the outrigger. The combination of components allows the patient's leg to be stabilized in a desired position and degree of flexion during knee arthroplasty, and to be easily released when desired for evaluation of the patient's leg in extension.