Related Experiment Video
Updated: Apr 13, 2026
Clinical-oriented Three-dimensional Gait Analysis Method for Evaluating Gait Disorder
Published on: March 4, 2018
Establishing Minimal Clinically Important Difference and Substantial Clinical Benefit Thresholds for Objective Gait
Roberta E Redfern1, Shujaa T Khan2, Michael J Archibeck3
1Clinical Affairs, Zimmer Biomet, Warsaw, Indiana.
Background:
Assessment of objective gait recovery in patients who are undergoing total knee arthroplasty (TKA) is becoming increasingly prevalent. However, few studies determined minimal clinically important difference (MCID) or substantial clinical benefit (SCB) thresholds in arthroplasty populations for clinical interpretation. This analysis aimed to calculate these values for various gait metrics following TKA.
Methods:
A secondary analysis of a longitudinal observational cohort of patients who underwent primary TKA was performed. Objective gait metrics were collected via wearables and smartphones from preoperatively to one year postoperatively. The EuroQol 5-Dimension 5-Level was completed by 2,146 study patients at preoperative and one year stages and used as the anchor to calculate MCID and SCB of each metric utilizing the receiver operating curve analysis (ROC-AUC) with Youden's Index. Baseline characteristics and outcomes were compared as a function of meeting the gait speed MCID.
Results:
The MCID thresholds were step count (1,227 steps), gait speed (0.067 meters per second), step length (0.02 meter), double support time (0.5%), and walking asymmetry (1%). The corresponding thresholds for SCB were step count (1,630 steps), gait speed (0.067 meters per second), step length (0.02 m), double support time (4%), and walking asymmetry (3%). At one year, 79% of patients met the MCID threshold for gait speed (0.067 meters per second). The average change in gait speed across the entire cohort was modest (0.017 ± 0.13 meters per second). Patients who achieved the MCID for gait speed had significantly worse preoperative profiles, including lower function, poorer quality of life, and higher levels of pain, compared to those who did not.
Conclusions:
This study established thresholds for clinical importance and benefit across multiple objective gait metrics, allowing interpretation of their clinical relevance. Clinically meaningful improvements in gait speed after TKA appear smaller than those reported in other musculoskeletal populations yet remain strongly associated with functional recovery and patient satisfaction. These standardized thresholds support integration of digital gait assessment into postoperative monitoring and individualized rehabilitation strategies.
