Concurrent validity and inter trial reliability of a single inertial measurement unit for spatial-temporal gait parameter analysis in patients with recent total hip or total knee arthroplasty.

Background: Osteoarthritis (OA) is one of the main causes of disability and its frequent hip and knee joint localization requires surgical joint replacement treatment. Patients after total hip (THA) or knee (TKA) arthroplasty often show gait abnormalities, whose comprehension is crucial in order to plan an appropriate rehabilitative treatment. Wearable sensor devices can be a valid tool for gait assessment in clinical practice, being relatively inexpensive and easy to use.

Research Question: Does the use of crutches influence the ability of a single inertial measurement unit (IMU), placed on the lower trunk, to correctly record the spatial-temporal gait parameters in patients after recent THA or TKA?

Methods: 20 patients walking with crutches after recent THA or TKA and 10 healthy subjects were recruited. Each participant was recorded simultaneously with an IMU and with an optoelectronic motion capture system during 5 consecutive walking tests.

Results: Intraclass correlation index of spatial-temporal parameters recorded with the IMU showed moderate to excellent reliability results both for healthy subjects (ICC range 0.626-0.897) and for patients (ICC range 0.596-0.951). In terms of concurrent validity, Pearson's r coefficient of healthy subjects, showed strong to very strong levels of correlations for some spatial-temporal parameters (speed, mean cadence, left and right stride length and stride duration) (r range 0.646-0.977) and very week to moderately week levels of correlation for gait cycle phases (swing, stance, single support and double support) (r range 0.390-0.633). Patients' data analysis showed similar results for general spatial-temporal parameters (r range 0.704-0.986) and slightly lower values for gait cycle phases (r range 0.077-0.464).

Significance: We can consider the single IMU as a reliable tool for the detection of some spatial-temporal gait parameters. Crutches seem to interfere with the detection of the gait cycle phases.