• A million cycles on a hip or knee simulator is considered a million steps an average person takes per year. Most test components are simulated up to 5 million cycles or equivalent to 5 years use in the body.

• Hip components when simulated typically have a ‘run-in’ phase followed by a ‘steady-state’ phase; ‘run-in’ usually occurs from 0-to-one million cycles (1Mc) at which it transitions in to ‘steady-state’ as illustrated in the wear graph.


• Hip components once implanted can undergo four (4) individual or combined modes of wear; those being:



• Tribology is the science and technology of interacting surfaces in relative motion. This includes the study and application of the principles of friction, lubrication and wear.

• The word tribology derives from the Greek τριβο (“tribo”) meaning ‘to rub’ and λόγος (“logos”) meaning ‘principle of logic’.

• Sir Robert Charnley was a pioneer and first to introduce a commercially available hip prosthesis for total hip replacement surgery (1969). His original acetabulum liner material was made from polytetrafluoroethylene (PTFE, Teflon) in 1958 which was replaced with ultra high molecular weight polyethylene (UHMWPE) in 1962 which has been marked as the gold standard of today.

Ankle-Foot Prosthesis Simulator

The Shore Western Ankle-Foot simulator is a new line of simulator in our biomedical systems portfolio running in accordance with ISO/DIS 22675. Recent data from the Amputee Coalition of America puts approx. 2 million people with some sort of limb loss within the USA (not including toes or fingers), combined with growth of new amputations performed annually at 185, 000 - performance investigation, design assessment and simulations of these prosthetics is evolving and growing rapidly. The Shore Western Ankle-Foot Prosthesis Simulator was designed to accomplish the growing demand that manufacturers of these devices demand.

The two axis ankle-foot simulator using servo hydraulic power runs under closed loop control feedback implementing displacement control for the angular movement of the tilting platform and load limited displacement control for the axial load. Load limited displacement control is a powerful control logic that enables dynamic load scenarios to run under the safe and stable control of a displacement environment while maintaining the programmed load level. Axial loads are available up to 6.8kN (1.5kip) supporting testing to the P6 level. Titling platform can produce 700Nm (6,000inlbs) of torque and has a total range of motion (ROM) of 60° (-20° to +40°). The tilting platform has changeable heel blocks to preserve the optimum heel height and the specimen holder has adjustable spring rates to return the foot to home after toe-off, its anterior to posterior slope is adjustable ±5° from the transverse plane. Test cycle speeds of 1.6Hz are achievable and can run 24 hours a day seven days a week with load/rotation and specimen failure detection shutdown.

SPECIFICATIONS

Single station ankle-foot simulator.

  • Two Axes – Two channel ankle-knee simulator orientated in one axial load and second controlling a tilting foot platform; each channel individually controlled.
  • Actuator Axes – Two separate actuator axes using servo hydraulic power under closed loop control feedback in displacement (titling platform) and load limited displacement (axial load).
  • Axial load – Axial load (Fz) up to 6800N (1500lb), to support loading levels up to P6 with 152mm (6”) of axial travel.
  • Fatigue rated – up to 9.8kN (2.2kip).
  • Tilting foot platform – Capable of producing 700Nm (6,000inlb) of torque, with a total range of motion (ROM) -20° to +40° from horizontal home position and lockable for static load testing at +20° and -15°.
  • Adjustable heel block – Changeable heel blocks to preserve optimum heel height.
  • Specimen holder – Adjustable spring rate controlled holder for return of foot to home position after toe-off combined with an adjustable anterior to posterior slope of ±5° from the transverse plane.
  • Speed – Up to 1.6Hz cycle speed, computer adjusted.
  • Access – Open load frame allows ease of sample assembly/disassembly.
  • Compact Footprint – Approx. footprint 610mm (24”) long X 735mm (30”) wide X 2515mm (99”) high.
  • 24/7 – Continuous 24 hour operation seven days a week with load/rotation and specimen failure detection shutdown.
  • Independent Control – Each actuator can be independently controlled under manual mode outside its normal automatic operation

OPTIONS

  • Protective Lexan Shields transparent cover from the length of the tilting foot platform to maximum height of load frame, obstructing ruptured material.
  • Calibration fixture a single axis calibration cell is used to calibrate the Fz load to full scale.