Objective Functional Phenotyping in Spine Surgery: A Translational Framework for Quantifying Disability, Guiding...

Imaging, physical examination, and patient-reported outcome measures (PROMs) remain central to spine care but incompletely characterize how spinal disease affects physical performance and how function changes following treatment. Objective assessment of gait, balance, functional transitions, lifting, and neuromuscular control provides complementary information regarding movement impairment, compensation, and recovery. This narrative review synthesizes current evidence supporting objective functional assessment in spine care and proposes Disability and Functional Outcome Measures (DFOMs) as a translational framework for organizing these measurements into clinically interpretable functional domains. DFOMs are not presented as a new measurement instrument or independently validated composite outcome; rather, the framework integrates established and emerging objective functional measures acquired through motion analysis, force platforms, electromyography, wearable sensors, and markerless technologies. Evidence supporting individual measures varies substantially with respect to validity, reliability, responsiveness, normative reference values, and clinical utility. Laboratory-based gait and balance assessment currently have the strongest evidence base, whereas multidomain composite scoring, markerless assessment, wearable-derived biomarkers, and artificial intelligence-enabled phenotyping remain at earlier stages of clinical translation. Objective functional phenotyping may ultimately complement structural and patient-reported assessment by providing a multidimensional characterization of disability and recovery. However, standardized protocols, multicenter validation, clinically meaningful thresholds, implementation studies, and evidence of incremental clinical utility are required before widespread adoption in routine spine care.