Characterization by margin of stability in lumbar fusion patients requiring gait supervision

Although gait supervision poses a key challenge in rehabilitation, no prior researcher has characterized the gait stability of patients requiring supervision. Recently, margin of stability (MoS) has gained prominence for assessing stability at specific moments.

Is it possible to characterize gait-under-supervision (GS) patients after extreme lateral interbody fusion (XLIF) using the MoS? Could the direction of instability depend on the form of impairments?

This cross-sectional study included 66 patients who underwent XLIF and were assessed one month postoperatively. The MoS was calculated as the distance from the extrapolated center of mass (XCoM) to the base of support (BoS) boundary of the XLIF insertion-side foot. The posterior AP-MoS indicated a posterior deviation, and the ML-MoS indicated a medial deviation, when the XCoM moved beyond the posterior and medial boundaries of the BoS, respectively. Multiple logistic regression analysis was performed to confirm the effects of such deviations on gait supervision. Decision tree analysis was adopted to identify impairments requiring resolution based on the direction of instability.

Forty-six patients were in the gait-independent group and 20 in the gait-supervision group. The odds ratio for posterior deviation was 106.896 (confidence interval (CI): 95 %, 12.572-1915.886) and 173.953 (CI: 95 %, 14.806-1287.583) for medial deviation. Knee extension and hip abduction strength significantly differentiated posterior and medial deviations.

The MoS successfully characterized GS patients' stability, offering valuable insights for resolving gait supervision. Our findings highlight the need for therapeutic interventions that consider the direction of instability.