Abstract
Introduction
Total Knee Arthroplasty (TKA) has been demonstrated to drastically improve a patient's quality of life. The outcomes following TKA are often reported by subjective patient reported outcome measurements (PROMs). However, there are few objective outcome measures following TKA, limiting the amount of information physicians can use to effectively guide a patient's recovery, especially in the first 3 weeks. Newly developed knee sensors have been able to ameliorate this problem by providing the physician with previously unobtainable objective data. Our study aims to evaluate the use of a wearable knee sensor device to measure functional outcomes (range of motion and steps) in real time.
Methods
29 patients who underwent primary, unilateral TKA were recruited for this IRB approved study. Patients were instructed how to use the device and associated mobile phone application preoperatively (Figure 1) and provided knee sensors to wear postoperatively (Figure 2). Patients wore the device for 3 weeks postoperatively to allow for data collection. The device recorded range of motion, number of steps, and percentage of physical therapy exercises completed. Patients were grouped by gender, age (<69 or >=70 years old), and BMI (<30 and >=30 kg/m2) for analysis of functional outcome measurements (maximum flexion, minimum extension, and number of steps). Unpaired two-sample t-tests were used to analyze differences between the groups.
Results
Patients were able to tolerate wearing the device without complication and the device collected functional outcome data appropriately as designed. After brief instruction, both patients and physicians were able to monitor patient data via the mobile phone application in real time. The mean maximum flexion and minimum extension did not significantly change from postoperative week 1 to postoperative week 2 and week 3. However, the mean number of steps taken increased from 4,923 steps in postoperative week 1 to 8,163 steps week 2 (p=0.01) and 11,615 steps week 3 (p<0.001) postoperatively. There were no statistically significant differences in maximum flexion, minimum extension, and number of steps between the different gender, age, and BMI groups.
Discussion and Conclusion
The knee sensor device used in our study proved to be useful in providing objective functional outcomes following TKA. The device was well tolerated by patients and the mobile phone applications were easy to use for the physicians and the patients. Real time tracking of patients' own range of motion, number of steps, and percentage of exercises completed may motivate them to further their own recovery process. There were wide ranges in the number of steps taken during each postoperative time interval. These results may help identify individuals who are recovering at a faster rate or those who may need more focused physical therapy. Subsequent larger studies can utilize the device to elucidate previously unknown recovery trends among different groups of patients following TKA. In the future, the device's ability to collect real time functional outcome data will allow physicians and other healthcare providers to create individualized physical therapy plans, thereby optimizing the patient's recovery process.
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