Cyclic off-center loading of the humeral head on the glenoid component of anatomic total shoulder replacements, known as rocking-horse motion, is associated with early fixation failure and loosening of the glenoid implant. We have a developed a biomechanical test system — modified from ASTM F 2028-08 — that includes continuous real-time tracking of glenoid component micromotion and subsidence throughout the entire rocking-horse test and correlation of those displacements to the humeral head component position. Utilizing this test system, we evaluate the effects test substrates, implant design and implant fixation techniques on the stability of glenoid components subjected to rocking-horse loading.

Mark Ehrensberger, PhD

Lima Corporate (2015-2107)

• Reed K, Bisogno M, Sreniawski K, Paterson P, Howard CS, Ehrensberger MT.  “A Comparison of Rocking Horse Loosening of Metal-Backed Versus All Polyethylene Glenoid Components.” 62nd Annual Meeting of the Orthopedic Research Society. 2016.
• Sreniawski K, Reed KB, Howard CS, Ehrensberger MT. “Rocking-Horse Loosening of Glenoid Components Cemented in Cadaver Bone and Bone Foam.” 60th Annual Meeting of the Orthopedic Research Society. 2014
• Reed KB, Rotella NA, Buran JR, Howard CS, Stegemann PM, Ehrensberger MT. “Comparision of Two Glenoid Component Cementing Techniques Using Real-time Tracking of Rocking-Horse Loosening.” 59th Annual Meeting of the Orthopedic Research Society. 2013.