The overall objective of the proposed in vitro studies is to measure proximal and distal load-sharing between the radius and ulna before and after surgical procedures designed to alter load transmission pathways. Carefully controlled studies of load transmission through the forearm, and form a biomechanical basis for surgical decisions related to the relief of wrist pain. New findings from these studies may also lead to better surgical procedures for wrist, forearm, and elbow problems. Custom designed miniature force transducers (load cells) will be placed into the proximal radius and distal ulna of a fresh frozen cadaveric forearm which is mounted in special fixed positions, applying force to the wrist through a load cell attached to the hydraulic actuator of the test machine, and recording outputs of all load cells while simultaneously measuring relative axial motion between the radius and ulna.
Three Specific Aims will be investigated.
Specific Aim 1 : We will study the effects of implanting a titanium radial head prosthesis upon distal ulnar force and proximal radial displacement during forearm loading tests. Variables to be investigated will include forearm rotation, interosseous membrane (IOM) status (intact and sectioned), and overall restored length of the radius (anatomic, 3 mm less than anatomic, 3 mm greater than anatomic).
Specific Aim 2 : We will study the effects of two surgical resection procedures of the distal ulna (Bowers' hemiresection and Feldon bone wafer removal) upon measured forces in the distal ulna and proximal radius and relative axial displacement between radius and ulna. Variables to be investigated will include forearm rotation, OIM status (intact and sectioned), radial head status (intact and removed) and ulnar variance (neutral, + 2 mm and + 4 mm).
Specific Aim 3 : We will study the effects of reconstructing the interosseous membrane with a soft tissue substitute upon measured forces in the distal ulna and proximal radius, and relative axial displacement between radius and ulna. Test variables will include forearm rotation, graft tissue type (flexor carpi radialis tendon or patellar tendon graft), and graft pretensions.
