Orthopedic simulator with integral load actuators

Abstract

An orthopedic simulator is provided with a plurality of test stations for each holding a test specimen. A plurality of load actuators are provided, with a respective load actuator for each of the test stations. The load actuators are substantially frictionless and configured to apply loads to the test specimens at the test stations.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front, perspective view of an orthopedic simulator in accordance with certain embodiments of the invention, with an external housing removed for illustrative purposes, and with forces being schematically depicted.

FIG. 2 a is a top view of the orthopedic simulator of FIG. 1; FIG. 2b is a front view; FIG. 2c is a bottom view and FIG. 2d is a side view.

FIG. 3 is a view similar to FIG. 1, illustrating the removability of a specimen containment module.

FIG. 4 depicts an exemplary embodiment of an assembled specimen containment module.

FIG. 5 is an exploded view of the specimen containment module of FIG. 4.

FIG. 6 is a side, partially cross-sectional view of the specimen containment module of FIG. 4.

FIG. 7 is a top view of a base of the specimen containment module of FIG. 4.

FIG. 8 is a schematic depiction of an embodiment of a circulation loop for circulating a temperature control fluid in a temperature control circuit.

FIG. 9 depicts two test stations, with one test station having a specimen containment module releasably attached thereto.

FIG. 10 schematically depicts an exemplary arrangement for circulating bath fluid.

FIG. 11 depicts an embodiment of a specimen containment module in an installed position.

FIG. 12 is a perspective view of the orthopedic simulator of FIG. 1, with an indication of the flexion and extension motion.

FIG. 13 is a cross-sectional view of a portion of a flexion/extension motion linkage in accordance with embodiments of the invention.

FIG. 14 is a perspective view of the orthopedic simulator of FIG. 1, with an indication of the lateral bending motion around an axis of rotation.

FIG. 15 is a rear perspective view of the orthopedic simulator of FIG. 1.

FIG. 16 is a perspective view of the orthopedic simulator of FIG. 1, with an indication of anterior/posterior and lateral translation motions.

FIG. 17 depicts a portion of an x-y slide assembly in accordance with embodiments of the present invention.

FIG. 18 is a perspective view of the x-y slide assembly in accordance with embodiments of the present invention.

FIG. 19 is an exploded view of the x-y slide assembly of FIG. 18.

FIG. 20 is a perspective view of the orthopedic simulator of FIG. 1, with an indication of loading in a vertical direction.

FIG. 21 is a perspective view of an embodiment of an actuator in isolation.

FIG. 22 is a top view of the actuator of FIG. 21.

FIG. 23 is a side view of the actuator of FIG. 21.

FIG. 24 is a cross-sectional view of the actuator of FIG. 21.

FIG. 25 is a perspective view of the orthopedic simulator of FIG. 1, with an indication of the axial rotation linkage and a moment provided at a test specimen.

FIG. 26 is a rear perspective view of the orthopedic simulator of FIG. 1, illustrating an embodiment of a central manifold in accordance with embodiments of the present invention.

FIGS. 27-29 schematically depict different approaches to linkages.

FIG. 30 schematically depicts a nesting order of forces in accordance with embodiments of the present invention.

FIG. 31 shows the required forces for application to a test specimen intended for a lumbar region according to an exemplary set of curves.

FIG. 32 shows the same information as FIG. 31, but for cervical data.

FIG. 33 shows curves for non-sinusoidal input data in accordance with exemplary embodiments of the invention.

FIG. 34 depicts the orthopedic simulator within a housing.

Claims

1. An integral load actuator comprising: a housing;a piston axially slideable within the housing;hydrostatic bearings that float the piston; andhydraulic fluid ports in the piston housing, with hydraulic fluid pressure in the hydraulic fluid ports controlling substantially frictionless extension and retraction of the piston with respect to the housing.

2. The actuator of claim 1, wherein the actuator is entirely seal-less.

3. The actuator of claim 2, wherein the piston is rotatable around a central longitudinal axis of the piston with extremely low torsional friction.

4. The actuator of claim 3, wherein the actuator includes a hydraulic shut-off valve that shuts off hydraulic pressure to the hydraulic fluid pressure ports.

5. The actuator of claim 4, further comprising thrust bearings at the axial ends of the housing.

6. An orthopedic simulator, comprising: a plurality of test stations for each holding a test specimen; anda plurality of load actuators, with a respective load actuator for each of the test stations, the load actuators being substantially frictionless and configured to apply loads to the test specimens at the test stations.

7. The simulator of claim 6, wherein the load actuators are hydraulically driven.

8. The simulator of claim 7, wherein the load actuators are simultaneously driven by hydraulic pressure to provide equal loads on the plurality of test specimens at the test stations.

9. The simulator of claim 8, wherein each load actuator has an individual shut-off valve to turn off the load actuator separately from the other load actuators.

10. The simulator of claim 9, wherein each load actuator is a vertical load actuator configured to apply vertical loads to a test specimen.

11. The simulator of claim 10, wherein each load actuator includes a housing and a piston axially slidable with the housing, hydrostatic bearings that float the piston, and hydraulic fluid ports that admit hydraulic fluid under pressure to control extension and retraction of the piston with respect to the housing.

12. The simulator of claim 11, wherein each load actuator is entirely seal-less.

13. The simulator of claim 12, wherein each piston is axially rotatable substantially frictionlessly.

14. The simulator of claim 13, wherein each load actuator has thrust bearings at the axial ends of the housing.

15. A spinal implant wear test machine, comprising: a plurality of test stations configured to hold test specimens in position for application of vertical load forces on the test specimens; anda plurality of vertical load actuators positioned relative to the test stations to apply the vertical load forces to the test specimens, each load actuator having a piston that is movable with extremely low linear friction to apply the vertical load forces.

16. The machine of claim 15, wherein the plurality of load actuators are commonly hydraulically driven to provide equal vertical loading of the test specimens across all of the load actuators.

17. The machine of claim 16, wherein the load actuators are hydrostatic and completely seal-less.

18. The machine of claim 17, wherein each load actuator has an individual shut-off valve to turn off the load actuator separately from the other load actuators.