Soft Tissue Balancing In Primary Total Knee Arthroplasty

Author : Patricia Franklin
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (125 download)

DOWNLOAD NOW!

Download or read book Sensor-Guided Total Knee Arthroplasty May Improve Early Pain And Function Outcomes written by Patricia Franklin and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: INTRODUCTION: Intraoperative ligament and soft tissue balancing during total knee arthroplasty (TKA) has a well-demonstrated role in establishing knee stability, improving limb alignment, and preventing implant loosening; therefore, appropriate soft tissue balancing is important for primary TKA success and avoiding revision surgery. The goal of ligament balancing is to reverse the soft tissue changes secondary to the bony deformities characteristic of arthritic changes; however, the evaluation of u201cbalanceu201d intraoperatively remains largely subjective, and therefore prone to variation. Sensor-guided soft tissue balancing is a recent development in TKA, and current literature has not established a strong connection between sensor-guided tissue balancing and improved patient reported knee-specific function, pain relief, and TKA longevity. This feasibility study explores the use of sensor-guided technology for soft tissue balancing in primary knee replacement, investigating first whether the sensors demonstrate a need for further soft tissue work, and second how patients with sensor-guided TKA perform in the early post-operative period with regard to clinical knee performance functional testing and patient reported pain when compared to patients whose knees were balanced by traditional methods.METHODS: The sensor group consisted of patients that underwent sensor-guided primary TKA with a single surgeon, as identified by retrospective chart review. The control group in this sequential series contained consecutive patients who underwent primary TKA with the same surgeon immediately prior to the sensor-guided cohort. The sensor (Versasense by Orthosensor) takes the form of a tibial trial component with microprocessor sensors that wirelessly transmit data to a monitor intra-operatively. It measures the medial and lateral compartment pressures (lbf.), tibiofemoral rotation, and the point of contact (Figure 1). After completion of the femoral and tibial bone cuts during TKA, the surgeon assessed soft tissue balancing and made surgical modifications as necessary. The surgeon then placed the femoral and tibial trial, and inserted the sensor into the tibial tray in lieu of a polyethylene trial. The knee was then guided through the range of motion as the sensor wirelessly transmitted loading pressure readings to the monitor. Data was relayed to the monitor in real-time during the full knee range of motion, and initial measurements were recorded at 10u00b0, 45u00b0, and 90u00b0 of flexion for each patient. The sensor designers defined the goal range of pressures as u201cgreenu201d at 5-40 lbf., moderately high pressures as u201cyellowu201d at 41-70 lbf., and high-pressures as u201credu201d over 70 lbf.. The surgeon used these guidelines and initial pressure values to inform further soft tissue modification, after which the sensor was inserted again to record the definitive pressures (Figure 2). Early post-operative function was measured for both groups using the Timed Up and Go (TUG) test, during which a patient stood from seated, walked ten feet, then returned to sit in the chair. The TUG test was completed at the last physical therapy session immediately prior to a TKA patientu2019s discharge, typically on post-operative day two. Patient-reported pain scores were also recorded at this session, based on the Wong-Baker 0-10 scale. Data was analyzed for differences between the sensor and control groupsu2019 TUG and pain scores, and for differences between the initial and definitive sensor measurements. Two-tailed student t-tests assuming unequal variance were conducted to determine if differences were statistically significant. Institutional Review Board approval was obtained for this study.RESULTS: 60 patients total were enrolled in the study, 36 in the sensor group and 24 controls. Within the sensor group, 14 patients began with an initial reading in the Red zone, 10 in the Yellow, and 8 began in the Green. After balancing, 2 patients were in the Red, 17 in Yellow and 15 in Green (Figure 3). The average absolute sensor pressure reading during the initial measurement was 30.20 lbf. (SD 18.61), compared to a lower average pressure reading of 24.30 lbf. (SD 8.53) in the definitive measurement. This average decrease of 5.90 lbf. in absolute pressures between initial and definitive measurements was found to be statistically significant (p = 0.000479). In comparing the TUG scores, the sensor group had an average TUG of 40.54 seconds (SD 20.75), which was significantly faster than the control groupu2019s mean TUG of 53.50 seconds (SD 23.60, p = 0.04711). Additionally, the sensor group reported an average pain level of 4.44 (SD 2.02) immediately prior to discharge, lower than the average pain level of 6.00 (SD 1.54) reported by the control patients (p=0.00171).DISCUSSION: This feasibility cohort study aims to determine whether sensor use in TKA may reliably guide soft tissue balancing, and whether this new technology is associated with improvements in early clinical outcomes. After preliminary balancing, the sensor detected that 24 patients had high contact pressures in the Red or Yellow categories, with an average pressure of 30.2 lbf. and a standard deviation of 18.61, demonstrating high variability in initial compartment pressures. After further soft tissue modification, only two patients had Red readings, the mean pressure was decreased to 24.30 lbf., and the standard deviation was reduced to 8.53 lbf., indicating a closer grouping of absolute pressures after sensor-guided balancing. The significant difference between initial and definitive trial pressures suggests the sensor readings do inform the surgeon in a way that allows them to make measurable changes in tissue balancing, and the closer distribution of final pressures indicates improved consistency of balancing with sensor use. Compared to the control group, the sensor group also had significantly faster TUG times and significantly less reported pain prior to discharge, suggesting sensor use improves early postoperative function and pain outcomes. SIGNIFICANCE/CLINICAL RELEVANCE: This feasibility cohort demonstrates that sensor trials can inform surgeon balancing associated with significant changes in absolute joint pressures, and also suggests patients with sensor-guided TKA have improved early post-operative pain and function outcomes, which may set them on a trajectory for better long-term outcomes and lower revision rates than patients without sensor-guided TKA. These preliminary data serve as the foundation for a larger pilot study exploring the long-term patient reported outcomes at 3, 6, and 12 months after sensor-guided balancing.