Knee - Wear and Fatigue Testing

Questmed GmbH offers lab tests for total knee replacement (TKR) for wear according to ISO 14243.
We are also specialised for testing unikondylar knee endoprosthesis and linked knee endoprosthesis.
It is also possible to perform wear testing in compliance with ASTM F3141.


Knee Wear Testing according ISO 14243 - Questmed GmbH Knee tibial tray fatigue testing according ISO 14879-1

Our knee wear simulator is available with two banks each with three test stations and two load soak stations. Our AMTI knee simulator (ADL-K6-01) replicates the loading and full range of multi-axis motion associated with activities of daily living. The test system provides unparalleled test accuracy through its virtual soft tissue control, which couples force control with a software model that accounts for the constraining influence of the tissue structure surrounding the knee. Our knee simulator meets the requirements of ISO standards for "Implants for surgery — Wear of total knee-joint prostheses" - ISO 14243-1:2009, ISO 14243-1:2009/Amd 1:2020, ISO 14243-3:2014, ISO 14243-3:2014/Amd 1:2020 and ASTM "Standard Guide for Total Knee Replacement Loading Profiles" ASTM F3141 - 17a.

Knee - Test methods

In our test lab we also perform the following test methods:
  • ASTM F1223 "Standard Test Method for Determination of Total Knee Replacement Constraint"
  • ASTM F1672 "Standard Specification for Resurfacing Patellar Prosthesis"
  • ASTM F1800 "Standard Practice for Cyclic Fatigue Testing of Metal Tibial Tray Components of Total Knee Joint Replacements"
  • ASTM F1814 "Standard Guide for Evaluating Modular Hip and Knee Joint Components"
  • ASTM F2003 "Standard Practice for Accelerated Aging of Ultra-High Molecular Weight Polyethylene after Gamma Irradiation in Air"
  • ASTM F2083 "Standard Specification for Knee Replacement Prosthesis" Total Knee Replacement Contact Pressure
  • ASTM F2722 "Standard Practice for Evaluating Mobile Bearing Knee Tibial Baseplate Rotational Stops"
  • ASTM F2723 "Standard Test Method for Evaluating Mobile Bearing Knee Tibial Baseplate/Bearing Resistance to Dynamic Disassociation"
  • ASTM F2724 "Standard Test Method for Evaluating Mobile Bearing Knee Dislocation"
  • ASTM F2777 "Standard Test Method for Evaluating Knee Bearing (Tibial Insert) Endurance and Deformation Under High Flexion" with 2.275 N for 220.000 cycles at 20 degree tibial internal rotation and hihg femoral flexion
  • ASTM F3140 "Standard Test Method for Cyclic Fatigue Testing of Metal Tibial Tray Components of Unicondylar Knee Joint Replacements"
  • ASTM F3210 "Standard Test Method for Fatigue Testing of Total Knee Femoral Components under Closing Conditions" with 90 degree flexion for 5 million cycles with 5Hz
  • ASTM F3306 "Standard Test Method for Ion Release Evaluation of Medical Implants"
  • ISO 7207-1 "Implants for surgery — Components for partial and total knee joint prostheses — Part 1: Classification, definitions and designation of dimensions"
  • ISO 5834-3 "Implants for surgery — Ultra-high-molecular-weight polyethylene — Part 3: Accelerated ageing methods"
  • ISO 21536 "Non-active surgical implants — Joint replacement implants — Specific requirements for knee-joint replacement implants"
  • Fatigue testing of stemmed TKR components

Knee - Wear Test ISO 14243-1 / ISO 14243-3

Parameters of the Wear Test: ISO 14243-1

The tests will be conducted load controlled so that the flexion and loads specified in ISO 14243-1:2009 will be applied to the test samples. The axial force specified in ISO 14243-1:2009 will be applied to the active load soak sample.

• axial force: 168 N – 2 600 N (gait cycle)
• flexion angle: 0 degree - 58 degree (gait cycle)
• AP force: -265 N - 110 N (gait cycle)
• tibial torque: -1 Nm - 6 Nm (gait cycle)
• test frequency: 1 Hz
• test temperature: 37°C +/- 2
• test medium: calf serum (protein content 20 g/l)
• cycles: 5 000 000

Parameters of the Wear Test: ISO 14243-3

The test will be conducted so that the force, flexion, motion and rotation specified in ISO 14243-3:2014 will be applied to the test samples. The axial force specified in ISO 14243-3:2014 will be applied to the active load soak samples.

• axial force: 168 N – 2 600 N (gait cycle)
• flexion angle: 0 degree - 58 degree (gait cycle)
• AP motion: 0 mm – 5.2 mm (gait cycle)
• tibial rotation: -5.7 degree – 1.9 degree (gait cycle)
• test frequency: 1 Hz
• test temperature: 37°C +/- 2
• test medium: calf serum (protein content 20 g/l)
• cycles: 5 000 000

Wear Measurement ISO 14243-2

The wear of the polyethylene components will be determined by the net mass loss WN according to ISO 14243-2. The polyethylene components will be weighted before and after the wear test as well as during the wear test overall seven times. The inspections will be determined after 500 000 cycles, 1 million cycles and every following 1 million cycles.

Test Preconditions
The components shall be sterilized in the same way as for clinical use.
The polyethylene components have to be soaked before the test for at least 11 days. We advise the pre-soak conditioning in calf serum for at least 20 days including gravimetric measurements.

Test Samples
Three test specimens (three stations) and one loaded control specimen shall be tested (complete knee joint prosthesis).

Knee - PE artifical aging ASTM F2003

The conditioning will be performed according ASTM F2003 and ISO 5834-3.
• test medium: oxygen
• 70 °C
• 503 kPa, 73 psi, 5.03 bar
• duration: 14 days

Knee - Tibial tray ASTM F1800 - ISO 14879-1

The tests will be conducted load controlled as specified in ISO 14879-1, ISO 21536, ASTM F1800 and ASTM F2083 will be applied to the test samples.
• 5 test samples
• axial force: at least 900 N
• test frequency: 10 Hz
• test medium: air
• cycles: 10 000 000

Knee - Contact area pressure ASTM F2083

The tests will be run at constant load as specified in ASTM F2083 at various flexion angles, with 0°, 15°, 30°, 60°, and 90° and 15° of internal and external rotation.

Knee - Unicondylar tibial tray ASTM F3140

The tests will be conducted load controlled as specified in ASTM F3140, ISO 21536, and ASTM F2083 will be applied to the test samples.
• 5 test samples
• axial force: at least 900 N
• test frequency: 10 Hz
• test medium: air
• cycles: 10 000 000

Knee - Femoral Component ASTM F3210

The tests will be conducted load controlled as specified in ASTM F3210 at 90° flexion.
This test simulates a clinically severe condition in which all bony support is lost and the femoral condyle is supporting the complete load of the knee joint at 90° of tibiofemoral flexion.
Different designs can be tested as posterior cruciate ligament retaining (CR), posterior stabilizing (PS), revision, and unicondylar.

Knee - Geometry and Classification ISO 7207-1

The determination of geometric data and classification will be performed as specified in ISO 7207-1.