ASTM F1829 describes a test method to determine the static shear force required to loosen modular glenoid components (insert and backing) of shoulder replacements. The test is suitable for metal joints, polymers, or composites and is used for design validation or comparison with other replacements. Wherever possible, the test should reflect the clinical use of the implant, meaning representative specimens of the finished product are tested and sterilized as required by the manufacturer.

For testing, specimens are fixed in the testing machine parallel to the implant axis. A vertical load is first applied from inferior to superior, and the loosening rate is recorded. The test is stopped when one of the following occurs:

• The insert separates from the backing
• The applied load reaches its maximum and begins to decrease
• Gross deformation of the insert occurs without loosening

After this, a new insert is placed in the test fixture, and the test is repeated under the same conditions but applied from anterior to posterior. The test is stopped again as soon as one of the above cases occurs. The backing is visually inspected for damage after each test.

At least five equivalent samples should be tested, and the test can be conducted either in air at room temperature or under defined physiological conditions.