Improving Partial Knee Replacement
A procedure called "unicompartmental knee arthroplasty" (UKA) is designed to be used when damage from osteoarthritis is limited to one compartment of the knee. However until now, this type of surgery has proved too complex to become the universal standard. Not only that, but success rates are slightly lower than those for total knee replacements (TKA). Yet because there are distinct benefits for patients who undergo UKA, researchers at Clemson University in South Carolina are exploring ways to improve knee implant design, surgical techniques, and patient selection criteria.
A release from the university points out that the advantages of UKA over TKA include preservation of bone stock, more physiologic joint movement, increased range of motion, and faster recovery time. UKA also results in improved proprioception, which is the ability to sense the position, location, orientation, and movement of the body and its parts.
The Clemson team has devised a knee simulator to help them determine whether various "failure modes" such as loosening and fracture are due to poor implant design, patient selection, alignment during surgery, or a mismatch between soft tissues and implant material. They note that all these could result in abnormal loading distributions on the knee, which could lead to "increased rates of clinical failure."
The Clemson rig, devised by doctoral candidate Roy Junius Rusly and colleagues, uses a 3-D tracking system to study such motions as getting up from a sitting position or rising from a crouch. The results of the experiment "will be analyzed and used to better understand the underlying causes of UKA failures, which the investigators hope will eventually lead to greater success for UKA."