Product Description
Elbow Prosthesis
Biomechanical research has shown that when the bumero-radial joint falls, the level of stress in the humero-unar joint is significantly higher. For this reason, it semmed wise when designing the Endo-Model® to incorporate all parts of the joint, in order to spread the load distribution of the forces over the widest possible area. Experience with the third generation St. Georg® Elbow had shown that it was only possible to achieve contact between the radial component and the radial humeral protruding gliding surface for all types of movement in approximately half of all cases. The unconstrained humero-radial joint prosthesis now enables much better adaptation to individual anatomical conditions, especially when the radisu head is more severely slanted and when this results in eccentric rotational movements.
The radial component basically comprises a metal ball and is anchored by means of a stem. A polythylene cap is pressed onto the ball and this can perform limited tilting movements in accordance with the duo-head prinicple. The bearing surface forms an acetabular-type radial protruding gliding surface of the ulnar component. The radial component and the acetabular protruding gliding surface make contact with one another by means of flat contact surfaces, whereby the internal diamter of the acetabular protruding gliding surface is larger thene the external diameter of the polythelene cap. In the case of rotary movements of the forearm, this allows eccentric deflection mvoements withing certain limtis and this is particularly the case if it has not been possible to fit the radial prosthetic stem in a way which is precisely in the radial axis direction. In addition to the various prosthetic stem lengths which are available for the radial component, additional spacers are also available in cases of bone defects in the proximal section of the radius.
The improvements which have been introduced to the model in terms of constructin and design hav eled to a significant optimisatin of the surgical technique. This has generally resulted in further improvement in the anchorage of the prostheses.
Humeral and ulnar comp[onents are anatomically shaped in AP as well as in ML. The humeral component bears flanged supports to prevent subsidence in the humeral bone. The ulnar component incorporates a protruding gliding surface for the individual radius head, providing for a replacement of the radial-humeral joint.
The radial component is available in stem lengths of 25, 30, 35 (short version) and 50, 55 and 60 mm (long version) in dias. & 5, 6 and 7 mm. In case of bone loss, cobaltchromium psacers of 5 mm height may be placed onto the stem of the raidal component, in order to fill the space of the missing bone.
