Method and apparatus for altering biomechanics of the shoulder
Selectively placed implants are specifically configured and dimensioned to address pathologies of the shoulder joint arising from improper force distribution. By using appropriately sized and positioned implants as described herein, displacement of targeted connective and muscle tissues acting on the shoulder is accomplished in order to realign force vectors and/or alter moment arms loading the joint to achieve therapeutic effects without cutting bone and with minimal cutting of the connective tissues.
1. A method for treating disorders of the shoulder, comprising mounting a prosthesis on the humerus at a fixation site to displace a target tissue comprising a connective tissue or muscle of the shoulder from a normal, anatomical path in at least one direction to alter loads applied by the connective tissue or muscle to the shoulder joint without cutting the humerus in said mounting or displacing, wherein said mounting and displacing are performed without rupturing a joint capsule of the shoulder or without the prosthesis entering any portion of the joint capsule.
2. The method of claim 1 , wherein the target tissue is a deltoid muscle and said displacement is in a lateral or antero-lateral or postero-lateral direction.
3. The method of claim 2 , wherein said mounting comprises mounting the implant cranially on the lateral side of the humeral shaft to displace the deltoid muscle around the humeral head.
4. The method of claim 1 , wherein said displacing decreases mechanical load on at least one region of the articular cartilage of the shoulder by at least about 5%.
5. The method of claim 1 , wherein the target tissue is a biceps brachii tendon and said displacement is in an anterior direction.
6. The method of claim 5 , wherein said mounting comprises mounting the implant cranially on the humeral shaft to displace the biceps brachii tendon.
7. The method of claim 1 , wherein said displacing decreases mechanical load on at least one of the rotator cuff tendons.
8. The method of claim 1 , wherein said displacing increases the stability of the shoulder joint during shoulder motion.
9. The method of claim 1 wherein the implant avoids interference with an acromion during arm abduction.
10. The method of claim 9 wherein the implant slips under the acromion during arm abduction.
11. The method of claim 9 wherein the implant is spaced laterally and/or caudally from the acromion when the arm is abducted.
12. A method for treating disorders of the shoulder, comprising mounting a prosthesis on the humerus at a fixation site to displace a target tissue comprising a connective tissue or muscle of the shoulder from a normal, anatomical path in at least one direction to alter loads applied by the connective tissue or muscle to the shoulder joint without cutting the humerus in said mounting or displacing, wherein:
the prosthesis comprises a fixation portion and a displacement portion separated and connected by a spanning section;
said mounting comprises securing the fixation portion to a fixation site on the proximal humeral shaft without rupturing the shoulder joint capsule; and
said displacing comprises positioning the displacement portion under and in engagement with the target tissue with the fixation portion secured at the fixation site.
13. The method of claim 12 , wherein said displacing comprises displacing the target tissue from its natural, anatomical path to a therapeutic path by a distance from greater than about 5 mm to about 30 mm.
14. The method of claim 12 , wherein said mounting and displacing are performed without rupturing a joint capsule of the shoulder or without the prosthesis entering any portion of the joint capsule.