OPLL Ossification Posterior Longitudinal Ligament Severity Index

Assess severity of ossification of the posterior longitudinal ligament (OPLL) using the occupancy ratio (ossification cross-sectional area divided by spinal canal area, multiplied by 100%). Occupancy above 60% correlates with high risk of myelopathy. Type classification: segmental, continuous, mixed, circumscribed. Mixed type has worst prognosis.

Weight
Height
Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.
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How It Works

Assess severity of ossification of the posterior longitudinal ligament (OPLL) using the occupancy ratio (ossification cross-sectional area divided by spinal canal area, multiplied by 100%). Occupancy above 60% correlates with high risk of myelopathy. Type classification: segmental, continuous, mixed, circumscribed. Mixed type has worst prognosis

Each component has a specific meaning:

  • Occupancy ratio (ossification cross-sectional area divided by spinal canal area — The occupancy ratio (ossification cross-sectional area divided by spinal canal area recorded for the scenario being assessed.
  • Multiplied by 100%) — The multiplied by 100%) recorded for the scenario being assessed.

Note: Interpret the opll severity index result against the thresholds and context described above.

How to Use

Enter the occupancy ratio (ossification cross-sectional area divided by spinal canal area, multiplied by 100%) for the scenario you are assessing. Assess severity of ossification of the posterior longitudinal ligament (OPLL) using the occupancy ratio (ossification cross-sectional area divided by spinal canal area, multiplied by 100%). Occupancy above 60% correlates with high risk of myelopathy. Type classification: segmental, continuous, mixed, circumscribed. Mixed type has worst prognosis. Use the opll severity index result to inform your calculation.

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Frequently Asked Questions