This is a single-site, prospective, observational, single-visit feasibility and validity study. Adult participants with and without low back or neck pain will be screened, consented, and enrolled to undergo a structured wearable-sensor-based spine assessment in a single on-site visit.

Approximately 20 participants will be enrolled at a single site:

• Approximately 10 adults with self-reported chronic or subacute low back or neck pain (LBP/Neck Pain group)
• Approximately 10 adults without current back or neck pain (Control group)

The AxiSens battery includes the Fingertip-to-Floor (FTF) test for lumbar flexion, the Chin-to-Chest (CTC) test for cervical flexion, a seated Trunk Stability Test on an unstable surface, the Cervical Flexor Endurance Test, the five-times sit-to-stand F5xSTS) test, and a brief functional task module covering overhead and forward reach.

To support intra-rater repeatability characterization, the AxiSens wearable assessment is performed twice within the same visit by a single trained operator, with sensor doffing and re-donning between the two assessments. A short rest interval is provided between the two assessments.

Following the on-site assessment, participants complete a brief end-of-session usability and tolerability questionnaire and the Technology Acceptance Model (TAM) questionnaire.

Low back and neck pain are among the most common, costly, and disabling musculoskeletal conditions in the United States and worldwide. Low back pain is the leading cause of years lived with disability globally, and neck pain is consistently within the top ten. Both are leading drivers of healthcare expenditure, exceeding spending on diabetes, heart disease, and cancer in some recent analyses. Despite this magnitude, the clinical assessment of spine function remains heavily reliant on subjective self-report and clinician examination, with limited use of objective, quantitative, point-of-care measurement tools.

Wearable sensors, particularly inertial measurement units (IMUs), have matured into a credible technology base for objective musculoskeletal assessment. Multiple research groups have published validation studies establishing the accuracy of IMU-based segmental kinematics against optical motion capture, and feasibility studies demonstrating the utility of wearable kinematics in occupational and clinical settings. Most published wearable-spine assessment work to date has focused on lumbar kinematics in isolation, with cervical kinematic assessment less well-developed and integrated full-spine kinematic assessment relatively rare.

Recent peer-reviewed work demonstrated the feasibility of using wearable IMU technology to objectively assess cervical and upper-back posture in high-risk professional populations during prolonged work tasks. This work established that IMU-based monitoring of upper-body kinematics is feasible in real-world settings and that the methodology generates objective, reproducible data suitable for biofeedback and longitudinal monitoring. The current study extends this established methodology to a broader spine assessment configuration covering cervical, thoracic, lumbar, and pelvic segments, and integrated with validated patient-reported outcome instruments to enable a holistic biopsychosocial assessment of spine function.

The objective of this study is to evaluate the ability of a wearable, multi-modal spine assessment system - AxiSens - to discriminate between adults with low back or neck pain and healthy controls, and to characterize its intra-rater repeatability and workflow feasibility. There is no investigational therapeutic intervention. All participants undergo the same wearable-sensor-based spine assessment procedures in a single on-site visit. Approximately 20 participants will be enrolled, comprising approximately 10 participants in the LBP/Neck Pain group and approximately 10 participants in the Control group.

To support intra-rater repeatability characterization within this single-visit design, the AxiSens wearable assessment is performed twice within the visit by a single trained operator, with sensor doffing and re-donning between the two assessments and a short rest interval. The two within-visit assessments support estimation of the intra-rater repeatability of AxiSens-derived kinematic and composite outcomes.

Inclusion Criteria:

• Male or female, aged 18-65 years
• Fluent in English (able to speak and read)
• Ambulatory without the need for a walking aid
• Able to independently perform all study activities safely, as determined by the investigator
• Willing and able to provide informed consent and comply with all study procedures

For LBP/Neck Pain participants:

• Self-reported low back or neck pain present for at least 4 weeks (subacute or chronic), with current Numeric Pain Rating Scale (NPRS) score of 3 or higher in the past 7 days
• No history of spine surgery within the past 12 months

For Control participants:

• No current low back or neck pain (NPRS < 2 in the past 30 days) and no history of clinically significant spine condition or spine surgery

Exclusion Criteria:

Participants meeting any of the following criteria will be excluded from the study:

• History of spine fracture, spinal deformity (e.g., scoliosis with Cobb angle > 25°), or spinal cord injury
• Active radicular signs requiring imaging or specialist referral, as determined by the investigator
• Neurological, vestibular, or musculoskeletal condition that would interfere with safe performance of the study tasks
• Pregnant individuals
• Skin condition or adhesive sensitivity precluding sensor application
• Body mass index (BMI) < 18 kg/m² or > 40 kg/m²
• Inability to provide informed consent or comply with study procedures

Healthy controls, individuals with neck pain, and individuals with low back pain.