A tension strap to be used with any brand of ACL or OA functional knee bracing. The position, elasticity and versatility of the strap allow it to be used for patella support and to prevent vertical migration of the brace. The strap is placed over the anterior side of the face of the knee joint with the support buttress lying adjacent to the anterior edge of the patella and the support straps extended posteriorly to the upper arms and lower arms of the brace. The support straps are then pulled around the outside of the upper arms and lower arms of the brace and adhered back to themselves using hook and loop fastener material. Additional support tension can be applied to the patella through the buttress support by increasing tension through the support straps. The prevention of vertical migration of the knee brace is also achieved through the use of non-slip lining on the face of the tension strap that is in contact with the skin covering the knee joint and patella.