Dynamic Fatigue Tests on Hip Endoprostheses to ISO 7206-4, ISO 7206-6, ISO 7206-8 and ASTM F2068

The hip joint consists of the femur and the pelvis. Diseases can make it necessary to replace parts of or the entire hip joint with an implant. 
Embedding device for hip endoprosthesis stems to ISO 7206 (5)

Dynamic Fatigue Tests on Hip Endoprostheses to ISO 7206-4, ISO 7206-6, ISO 7206-8 and ASTM F2068

The ZwickRoell servohydraulic testing machine HC Compact or the LTM is used to simulate dynamic loadings on a hip prosthesis stem in accordance with the relevant standards, ISO 7206-4, ISO 7206-6, ISO 7206-8 and ASTM F2068. Use of the appropriate ZwickRoell embedding device enables the mechanical conditions specified in the standard, such as the orientation of the hip joint prosthesis to the test load or the embedding height, together with the angle of load application, to be defined with accuracy. 

 

ISO 7206 Implants for Surgery – Partial and Total Hip Joint Prosthesis

ZwickRoell's hip endoprosthesis test fixture fulfills the requirements of ISO 7206 Implants for surgery - Partial and total hip joint prostheses.

Determination of endurance properties of stemmed femoral components

A minimum of six hip endoprosthesis stems must withstand 5 million load cycles with a maximum load of 2300 N and a minimum load of 300 N.

  • Number of cycles: 5 million (6 specimens)
  • Test frequency: up to 30 Hz
  • Load (ASTM F2068-03; ISO 7206-8): Fo: 2300 N; Fu: 300 N

Determination of endurance properties of head and neck region of stemmed femoral components

A minimum of six hip endoprosthesis stems must withstand 10 million load cycles at a load of 5.34 kN (R=0.1).

  • Number of cycles: 10 million (6 specimens)
  • Test frequency: up to 30 Hz
  • Load (ASTM F2068-03): Fo: 5340 N; Fu: 534 N

Endurance performance of stemmed femoral components with application of torsion

  • A precision-manufactured embedding device is used to embed the stem, ensuring exact orientation of the implant to the test loads.
  • Head and foot flange assembly for simple and durable installation, taking into consideration the necessary degrees of freedom for the test.

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Lever out test

Lever-out testing on hip joint pairings

Torsion test on artificial hip joints

Torsion Tests on Artificial Ball Joints

Artificial hip joints must withstand both compressive loads and torsion loads. To determine the optimum materials and alloys, these are tested with a special testing machine,

consisting of a 20-kN ZwickRoell materials testing machine plus a 500-Nm torsion drive.

The artificial hip joint (here made of metal) is rotated on a support unit (torsion loading) and compression loading is applied at the same time. This tests materials and alloys best suited for artificial hip joints.

  • ISO 7206-9:1994 (Determination of resistance to torque of head fixation of stemmed femoral components)
  • Characterization of the resistance of a hip joint head to torques in normal in-vivo use
  • Makes it possible to develop a better anchor between the two components
  • Application of a static compression preload, the transverse torque then increases until the head turns
  • Static biaxial testing machine (20 kN) with 500-Nm torque motor
Testing of the anchoring of a hip endoprosthesis

Testing of the Anchoring of a Hip Endoprosthesis

Hip endoprostheses can be anchored in the femur with or without the use of bone cement. In addition to high cycle fatigue tests on the prosthesis itself, the strength of the fastening in the bone must also be tested. For this, an endoprosthesis is anchored in natural or artificial bone, the load axis is adjusted by means of a clamping fixture and the entire test device is clamped in an AllroundLine testing machine 20 kN. During cyclic loading, loads can be measured, together with any micro-movements between prosthesis and bone.

Customized implants – ZwickRoell delivers innovate testing technology to Karl Landsteiner University of Health Sciences

Technology always greatly impacts medicine. This is due to demographic changes and the associated socioeconomic challenges to the health care system. Innovations through customization in medical technology are necessary to maintain the current high standard. Musculoskeletal diseases such as osteoporosis or osteoarthritis are among the top five diseases in old age.
KL University Krems
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