Fixing Joint Replacements to Bone: Lessons Learned from Postmortem
Retrievals
Dr. Kenneth A. Mann, Professor, Department of Orthopaedic Surgery, SUNY Upstate Medical
University
ABSTRACT
There are over 600,000 total knee replacements (TKR) and 200,000 total hip replacements (THR)
performed in the US each year and the number of joint replacements is expected to rise to over 3
Million/year by 2030. Generally, TKR and THR are very successful medical procedures with
substantial improvement in patient functional status and quality of life. Unfortunately, while the
majority of joint replacements function successfully for many years, the revision rate at 10 years
post-op is approximately 10%, with higher revision rates for younger, heavier, and more active
patients. The leading cause of revision is aseptic loosening, resulting in loss of fixation between
the implant and supporting bone.
Our research group at SUNY Upstate has been investigating the fixation between implants and
bone from human postmortem retrievals. In contrast to intra-operative retrievals from failed joint
replacements, postmortem retrievals can be used to provide insight into how well functioning joint
replacements are fixed to bone. The morphology of the fixation interfaces and motion of the
interfaces (micro-motion) can be quantified for functional loading situations. Results will be
presented for both cemented and uncemented implant systems. In addition, some potential
mechanisms that could explain the loss of interlock between implant and bone are explored.
Results from this work can be used to developed improved surgical techniques, implant designs,
and biomaterial features that can insure long term fixation of the bone-implant interfaces.
BIOGRAPHY
Kenneth A. Mann, PhD is Professor and Director of the Musculoskeletal Science Research
Center at the SUNY Upstate Medical University in Syracuse, New York. Dr. Mann received his
BS degree from Virginia Tech (1983), MS from Penn State (1985), and PhD from the Cornell
University-Hospital for Special Surgery Program in Biomechanical Engineering (1991). His
research interests are in the broad area of musculoskeletal biomechanics with particular interest
in micromechanics and micro-mechanical modeling of bone-implant interfaces, and with efforts to
improve long-term function of joint replacements. He is currently Associate Editor of the Journal
of Orthopaedic Research and on the review board of the International Journal of Maxillofacial
Implants and Veterinary and Comparative Orthopaedics and Traumatology. He served as regular
member of the NIH Skeletal Biology, Structure, and Regeneration (SBSR) study section (20052008) and has served regularly on grant review panels since 2001.