Current Research Projects

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.

Magnesium and many of its alloys are bioresorbable metals with mechanical properties closely aligned to natural bone. Its degradation (corrosion) products are postulated to stimulate osteogenic differentiation of mesenchymal stem cells. As such, these materials hold great promise for developing a new generation of orthopaedic devices and bone tissue engineering scaffolds with biomimetic mechanical properties, tailored corrosive degradation and resorption as well as preferential stimulation of osteogenesis. Since the implant would eventually degrade away, this also eliminates the need for a second surgery for hardware removal, and it would minimize the risk of a chronic foreign body reaction that can lead to fibrous bone healing and encapsulation of implants.  

An inflammatory response, characterized by low pH and generation of reactive oxygen species, is provoked by the invasive nature of implanting metallic orthopaedic devices in the body. This project seeks to understand how the conditions created by the inflammatory response influence the corrosion of traditional and next-generation metals utilized for orthopaedic implants.

Infection following orthopaedic interventions is a devastating complication associated with increased patient morbidity, longer hospital stays and increased costs to the health care system. One of the primary mechanisms by which bacteria resist decontamination and persist in wounds and on implants is through the formation of biofilms. Bacteria in biofilms are highly resistant to antibiotics and necessitate the development of new strategies for the eradication and/or prevention of device-related biofilm infections.

Rotational cutting tools, known as reamers, are used in a variety of orthopaedic surgeries ranging from intramedullary nailing of long bone fractures to total joint arthroplasty. Clinical concerns with reaming include thermal necrosis of the bone tissue and pressure-generated emboli, both of which are related to the reaming mechanics.

Reverse total shoulder arthroplasty has been shown to be an effective treatment for patients with rotator cuff tears and deficiencies. With the loss of rotator cuff strength, superior subluxation of the humeral head becomes a problem leading to excessive wear and superior glenoid bone deficiency. The presence of this superior defect can lead to complications when performing reverse total shoulder arthroplasty largely due to glenoid baseplate loosening.

Accurate and non-invasive measurement of the contact area between articulating surfaces of a load-bearing joint has a broad range of orthopaedic applications. A new cone beam CT system has been developed for imaging of extremities under load bearing conditions. This system also has novel analytical tools that include measurement of joint contact area and joint contact pressure distribution.