The Uncemented Evolution.
A new method for total elbow arthroplasty.
Design Features
The Kaufmann Total Elbow (KTE) arthroplasty is not cemented and uses intramedullary screws to gain purchase into the threaded intramedullary canals of the humerus and ulna. Cross locking screws that engage cross locking plates augment the construct’s stability. In distinction to semiconstrained implants, this design does not exhibit a direct mechanical pin linkage between the humeral and ulnar components.
The KTE reproduces the valgus carrying angle of the human elbow. The humeral and ulnar components are designed to both contribute with the humeral component demonstrating a 5.9 degree valgus alignment between the long axis of the humerus and the centerline of ulnohumeral rotation. The ulnar body component has a 7 degree valgus alignment between the long axis of the ulna and the centerline of ulnohumeral rotation. These angles were identified based on radiographic and cadaver measurements.
The hinge is not mechanically linked and employs laxity that allows for varus and valgus deviation. The hinge employs a snap fit that allows the humeral component to snap into the polyethylene component. It is a loose connection that provides proprioceptive feedback to the surgeon when implanting the components. The gentle snap fit is designed to mimic the capsule that surrounds the elbow by supplying some stability and maintaining ulnohumeral alignment, particularly during implantation. The varus valgus laxity of this implant is 7 degrees with 3.5 degrees in both varus and valgus directions, which is the same laxity as is employed in semi-constrained elbow arthroplasty.
The primary stability, however, is derived from the elbow ligament reconstruction, which is designed to transmit forces between the humerus and ulna and aims to mimic the primary static stabilizers of the elbow.
The medial and lateral collateral ligaments are considered essential stabilizers of both mechanically linked and non mechanically linked implants.
Particularly in abduction and adduction, the elbow experiences substantial varus and valgus forces, which make the collateral ligament integrity vital for proper elbow function.
Uncemented elbow replacements require osseointegration for the bone to secure the implant. Because this arthroplasty design is stabilized with a ligament reconstruction, ligament incorporation into bone is also required. While both of these processes happen, elbow replacements will face biomechanical challenges while osseointegration and ligament incorporation is occurring. We believe that substantial ligament healing will occur in three months and that bone incorporation will occur before that.IM SCREW MODULARITY
DIFFERENT SCREW LENGTHS AND DIAMETERS
Published Articles
Soft Tissue Stabilizers
Soft tissue stabilizers play a key role in maintaining stability of the elbow.
kaufmann_soft_tissue_stabilizers.pdfREAD MORE
Biomechanics and Failure
Total elbow arthroplasty. Biomechanics and failure.
kaufmann_tea_biomech_failure.pdfREAD MORE
Bone and Dynamic Stabilizers
Bone and dynamic stabilizers contribute to elbow stability
wilps_bone_dynamic_stabilizers.pdfREAD MORE