Translating biomechanics to clinic: validating a spine-specific wearable for remote functional assessment.

BACKGROUND CONTEXT: Disability and impaired function are hallmarks of spine pathology. Current clinical tools fail to quantitatively capture these functional deficits. Laboratory-based motion analysis offers precision but is costly and impractical for routine care. Wearable IMUs are a promising alternative; however, rigorous validation of spine-specific wearables during functional tasks remains limited. The clinical adoption of single-sensor IMUs has been limited because their accuracy depends on subject-specific calibration, drift correction, and high-fidelity sensor fusion, technical considerations that have not been fully validated in spine-specific, functional tasks, highlighting the need for systematic evaluation to determine their clinical utility.

PURPOSE: To validate a novel spine-specific wearable IMU device for accurate, clinically meaningful assessment of trunk kinematics and functional performance in patients with degenerative and structural spine disorders.

STUDY

DESIGN

Prospective, single-center validation of spine-specific wearable inertial measurement units (IMUs) compared with traditional motion capture technology.

METHODS

A total of 50 adults with spine pathology (mean age 63.2±11.8 years; BMI 31.1±6.6 kg/m²) performed gait, quiet standing, standardized lifting, and sit-to-stand tasks wearing a spine-specific IMU worn externally at the level of T1. The device was calibrated per participant to define a neutral trunk reference, and drift was minimized using sensor fusion algorithms. Data was recorded simultaneously with a 10-camera marker-based motion capture system. Trunk kinematics and balance metrics were compared using intraclass correlation coefficients (ICC), root mean square deviation (RMSD), and waveform correlations.

RESULTS

The IMU showed excellent agreement with traditional motion capture for sagittal plane peak flexion/extension across tasks (ICC 0.89-0.96), with root mean square deviation (RMSD) <5°. Coronal and transverse plane peak angles showed good-to-excellent reliability (ICC 0.71-0.94) and moderate range-of-motion agreement. Pattern correlations ranged from moderate to near-perfect (r=0.60-0.99), with the strongest reliability during lifting and sit-to-stand tasks. These tasks represent the majority of daily functional activities in spine patients, capturing spinal loading, postural control, and transitional movements, highlighting both clinical relevance and potential for perioperative and rehabilitation monitoring.

CONCLUSIONS

Spine-specific wearable IMUs accurately and reliably quantify trunk motion and balance in spine patients with spine pathology. Through high-precision engineering and validated measurement algorithms, these devices provide objective, actionable insights that extend beyond laboratory settings, enabling remote, continuous functional assessment and supporting personalized rehabilitation and longitudinal monitoring.

CLINICAL SIGNIFICANCE: Validated spine-specific wearable IMUs allow clinicians to objectively track functional recovery in real-world settings, identify compensatory movement strategies, optimize rehabilitation interventions, and enhance postoperative and longitudinal outcome surveillance, bridging the gap between engineering precision and patient-centered spine care.