Prosthetic joints having reduced area bearing surfaces and application thereof to a range of sizes of prosthetic joints
A prosthetic component is configured to have intentional interruptions in an articulating face thereof. The intentional interruptions are configured to yield an optimum contact area or bearing surface, particularly with regard to low wear and greater lubricity through the application of lubrication and contact mechanics theory for the particular prosthetic component. Such optimization is applied to a wide range of prosthetic component sizes of the particular prosthetic component. The optimum range of percentage area of relief or interruptions, defined as a percentage of a baseline uninterrupted bearing surface area to be removed by the features of the interrupted bearing surface configuration is from 0.3% to 73.7% for hard-on-hard bearing components and from 5.7% to 83.2% for polyethylene-on-hard bearing components. The range for both hard-on-hard and polyethylene-on-hard implants translates to a relieved area ranging from 0.3% to 31.9% of the area of the entire articulating surface, depending on the size of the implant. For both hard-on-hard and polyethylene-on-hard bearing combinations, optimally decreasing the contact area or bearing surface by interruptions in the articulating surfaces will allow for the benefits of larger diameter prosthetic components with an increased range of motion and decreased potential for dislocation, and the low frictional torques and lower wear of smaller diameter components.
1. A method of making a prosthetic joint, comprising the steps of:
determining a clearance distance between (i) a first articular surface of a first component of said prosthetic joint, and (ii) a second articular surface of a second component of said prosthetic joint;
deriving a baseline contact area value for said first articular surface and said second articular surface; and
forming interruptions in both said first articular surface and said second articular surface based on said baseline contact area value.
2. The method of claim 1 , wherein the step of deriving said baseline contact area value includes the step of performing Hertzian analysis.
3. The method of claim 2 , wherein the step of performing Hertzian analysis includes the step of applying contact mechanic equations.
4. The method of claim 2 , wherein the step of deriving a baseline contact area value includes calculating a contact area of a low-wearing prosthetic joint.
5. The method of claim 1 , wherein said forming step in includes the step of forming said interruptions in both said first articular surface and said second articular surface to a depth of less than one millimeter.
6. The method of claim 1 , wherein:
said first component is formed of a first material,
said second component is formed of a second material, and
said first material is different from said second material.
7. The method of claim 6 , wherein:
said first material includes metal, and
said second material includes plastic.
8. The method of claim 7 , wherein said plastic includes a polyethylene material.
9. The method of claim 7 , wherein said metal includes cobalt chromium.
10. The method of claim 1 , wherein:
said first material includes metal, and
said second material includes metal.
11. The method of claim 10 , wherein said metal includes cobalt chromium.
12. The method of claim 1 , wherein:
said first material includes ceramic, and
said second material includes ceramic.
13. The method of claim 12 , wherein said ceramic is selected from the group consisting of: alumina and zirconia.