Hybrid assistive limb treatment for patients with severe cervical and thoracic myelopathy due to ossification of the posterior longitudinal ligament and ligamentum flavum: Feasibility, safety, and efficacy in the acute and chronic phases.

Objective: To assess the feasibility, safety, and efficacy of hybrid assistive limb (HAL) training in patients with varying levels of gait impairment caused by ossification of the posterior longitudinal ligament (OPLL) or ligamentum flavum (OLF).

Design: Prospective study.

Setting: July 2014 to May 2019; in - and out-patient rehabilitation unit. Participants: Twenty-five patients with varying levels of ossified lesions and acute, subacute, or chronic postoperative OPLL or OLF.

Interventions: Ten HAL training sessions (sixty min) in total; three times per week (acute/subacute patients) or one time per two months (chronic patients).

Outcome measures: Walking Index for Spinal Cord Injury, American Spinal Injury Association (ASIA) Impairment Scale, ASIA motor score, Functional Independence Measure (FIM) motor score for activities of daily living, Berg Balance Scale, and Japanese Orthopedic Association score. Walking capabilities, including gait speed, step length, and cadence, were assessed using 10-meter and 2-minute walking tests (10/2MWT).

Results: All patients completed 10 HAL training sessions without severe adverse events. In the acute/subacute group, all measures showed significant improvements, except the 2MWT. In the chronic group, the gait speed, step length, and ASIA motor, FIM motor, and 2MWT scores significantly improved. Baseline and after-10-sessions estimated marginal means were compared for the acute, subacute, and chronic groups. All items were significant in the acute/subacute groups. In the chronic group, gait speed, step length, ASIA motor score, and 2MWT results were significant.

Conclusion: HAL treatment is feasible, safe, and effective in patients with different degrees of ossified lesions, specifically in those with OPLL or OLF.Trial Registration: UMIN000014336.