Validity, Reliability, and Clinical Correlation Study of the Turkish Translation of the Modified JOA (Japanese Orthopedic Association) Cervical Myelopathy Score

Degenerative cervical myelopathy (DCM) represents the leading cause of non-traumatic spinal cord dysfunction in adults and is characterized by progressive neurological impairment involving upper and lower extremity motor function, sensory deficits, and sphincter dysfunction. Standardized and reliable clinical assessment tools are essential for determining disease severity, guiding treatment decisions, and ensuring comparability across clinical studies.

The Modified Japanese Orthopaedic Association (mJOA) score is a clinician-based functional assessment tool widely used to evaluate neurological status in patients with DCM. It assesses four domains: upper extremity motor function (0-5 points), lower extremity motor function (0-7 points), sensory function (0-3 points), and sphincter function (0-3 points), yielding a total score ranging from 0 to 18. Lower scores indicate more severe neurological impairment. Although the mJOA score has undergone cross-cultural adaptation and validation in several languages, a culturally adapted and psychometrically validated Turkish version is currently unavailable.

This study is designed as a prospective, cross-sectional validation study aiming to perform the cultural adaptation and psychometric evaluation of the Turkish version of the mJOA score in patients with DCM. The translation process was conducted using a standardized forward-backward translation methodology in accordance with internationally accepted cross-cultural adaptation guidelines.

Participants will include adult patients (≥18 years) with clinically and radiologically confirmed DCM who present to the outpatient clinics of Physical Medicine and Rehabilitation and Neurosurgery. Previously obtained cervical magnetic resonance imaging (MRI) scans will be reviewed retrospectively to determine the level of cervical myelomalacia. Demographic and clinical variables, including age, sex, body mass index, symptom duration, treatment status, and affected side, will be recorded.

Construct validity will be evaluated by analyzing correlations between Turkish mJOA total and subdomain scores and the Neck Disability Index (NDI), a validated Turkish instrument measuring cervical disability. Given that higher mJOA scores reflect better neurological function and higher NDI scores indicate greater disability, a significant negative correlation is hypothesized. Additionally, correlations between mJOA scores and the Nurick grading system will be assessed using Spearman's rank correlation analysis. Differences in mJOA scores across categorized Nurick severity groups will be analyzed using non-parametric statistical tests.