Variance of Fixed Joint Space Width and Nomogram to Predict Knee Replacement using Measures from Fixed Flexion Knee X-rays

Case ID:

The cartilage underneath our knees keeps the bones in our legs from rubbing together. Unfortunately for many, this cartilage wears abnormally thin over time and causes physiological problems. If, however, this can be detected before it becomes a serious issue for the patient, then the patient can receive treatments before the painful problem can be fully realized.

This technology seeks to aid in just that: assessing the current health and predicting the future health of cartilage in the knees. It works by reading multiple x-rays of the region and then calculating/inspecting the different aspects of the cartilage by using measurements of Joint Space Width (JSW) and observing how it varies. One application would be identification of individuals who are at high risk of undergoing knee replacement in the next 2, 5 or 7 years.

Current measurement methods are unreliable as they use minimum joint space width (mJSW) technology to take crude physical measurements (width, length) to make the assessment.

This technology is able to detect variance in a greater number of parameters, such as curvature, joint loading, and asymmetry and early trials have shown to be very promising.


  • Assessing current knee health
  • Predicting if surgery will be needed, and how soon


  • Accurate
  • Safe
Patent Information:
Contact For More Information:
Lewis Humphreys
Licensing Manager, Eller College of Mngmt & OTT
The University of Arizona
Lead Inventor(s):
Chian Kwoh
Erin Ashbeck
Edward Bedrick
Jeffrey Duryea