Use of a force measuring walker to optimize recovery after median sternotomy

Abstract

\n \n \n Type of funding sources: None.\n BACKGROUND\n Patients often need to use their arms to assist with functional activities, but after open-heart surgery, pushing with the arms is often limited to <10 lb (4.5 kg), to minimize force across the healing sternum. Restricting arm use often limits patient functional independence which can contribute to longer hospital stays and greater need for care after hospitalization. Therefore, appropriate arm use is important for return to function.\xa0Currently, no method exists to measure patient upper extremity weight bearing (UEWB) forces objectively in clinical settings. The ultimate goal was to develop a walker that provides UEWB force feedback to patients recovering from median sternotomy. This research project included three interrelated parts that sequentially built on each other.\n PART 1\n First, I conducted a secondary data analysis comparing UEWB force and Pectoralis Major Muscle EMG during functional mobility in younger vs. older subjects (n = 65). Results showed that the mean arm force was >10 lb before feedback training during all functional mobility tasks for both groups. There were significant differences in UEWB force and EMG between groups (young vs. old) and trials (pre- vs. post-feedback training). There was significantly greater improvement (change) in the UEWB force in the older than younger subjects. We also found a significantly greater reduction in EMG activity in the older subjects than younger subjects for all tasks except during stand-to-sit. Results suggested that patients, particularly older ones, may not accurately estimate UEWB force <10 lb, and feedback training is effective for improving accuracy. This established proof-of-concept, the need for a Clinical Force Measuring (CFM) walker, and the efficacy of its use with feedback training.\n PART 2\n Next, I completed a qualitative study to obtain critiques of a CFM walker prototype from rehabilitation professionals through structured interviews that were recorded and transcribed. I coded key statements and phrases that allowed themes to emerge (Table 1), which guided device revisions.\n PART 3\n Lastly, I fabricated and tested a second CFM Walker prototype (Figure 1) based on key design elements including: 1) integrated vertical force measuring capability, 2) ergonomic handles, 3) simple visual and auditory feedback with upper limit alarms, 4) streamline, stable, and manoeuvrable\xa0frame, 5) lightweight construction, 6) minimal drag, 7) adjustable height, 8) ability to disinfect, and 9) affordable cost.\n CONCLUSIONS\n The CFM Walker could help patients recover safer and faster from open heart surgery, especially elderly adults.\n