Abstract
Total knee arthroplasty (TKA) is currently one of the most common elective surgical procedures in the United States. The increase in the proportion of younger patients in receipt of surgery, in concert with a dramatic rise in the incidence of obesity, has contributed to the on-going, exponential increase in the number of arthroplasties performed annually. Despite materials advances for implants, the U.S. revision burden has remained static for the last decade. According to the 2013 CMS MEDPAR file the typical CMS reimbursement falls far short of costs incurred by the hospital, resulting in an average net loss of revenue of $9,539; and over 90% of hospitals lose money for every revision case performed. Today, approximately 5% of all primaries performed will result in an early revision (< 3 years). In order to understand ways with which to mitigate the incidence of early revision due to mechanical complications, a multicentric group of sensor-assisted patients was follow-up out to 3 years.
In this study, 278 sensor-assisted patients were followed out to 3 years. The intraoperative devices used in this study contain microsensors and a processing unit. Kinetic and center of load location data are projected, in real-time, to a screen. Because of the wireless nature of the intraoperative sensors, the patella can be reduced, and kinematic data can be evaluated through the range of motion. For each patient, the soft-tissue envelope was balanced to within a mediolateral differential of 15 lbf., through the ROM, as per the suggestion of previously reported literature. The average patient profile indicates: age = 69.7 years, BMI = 30.4, gender distribution = 36% male/64% female. Any adverse event within the 3-year follow-up interval was captured.
By 3 years, 1 patient in this population has required revision surgeon due to mechanical complicatons. Overall adverse events included: pain in hip (3), pain in contralateral knee (2), wound drainage (3), DVT (1), death (1), stiffness in operative knee (2), infection (3), global pain (2), back pain (2).
Based on the average reported number of early revisions that occur in the U.S. (5% of primaries), it was anticipated for this patient group to require approximately 13 revisions by the 3-year follow-up interval. Using 2013 CMS MEDPAR data, these 13 revisions would have resulted in $124,007 cost-to-hospital. However, only 1 revision (0.4%) was observered, therefore $114,468 in additional costs were spared for the aggregate of participating hospitals. This data suggests that the incorporation of kinetic sensors in TKA may assist the surgeon in achieving soft-tissue balance and thereby avoiding adverse mechanical complications that require surgical intervention.
