This 1989 Knee Society paper by Ewald introduces a standardized one-page roentgenographic evaluation system for total knee arthroplasty. It provides a uniform method for measuring radiolucent lines in defined zones across tibial, femoral, and patellar components. The goal is to enable meaningful comparisons of radiographic outcomes across surgeons, implants, and institutions.
When you follow a TKA patient radiographically, this system is the standard language everyone uses to report what you see.
Score the tibial component first: add up radiolucent line widths across all zones. A total below 5 mm that is not progressing can be watched. A score of 5–9 mm warrants serial films. A score of 10 mm or more means the component is failing, whether or not the patient has symptoms yet.
Do not let a reassuring score override what you see on the film. If the component has shifted position compared to prior imaging, that is failure by definition — the score becomes irrelevant.
One limitation worth internalizing: this system cannot detect pure axial subsidence. If a tibial tray is sinking straight down without rotating, angular measurements will look normal. Serial film comparison and careful attention to joint line position are the only ways to catch this.
This 1989 Knee Society paper by Ewald introduces a standardized one-page roentgenographic evaluation system for total knee arthroplasty. It provides a uniform method for measuring radiolucent lines in defined zones across tibial, femoral, and patellar components. The goal is to enable meaningful comparisons of radiographic outcomes across surgeons, implants, and institutions.
When you follow a TKA patient radiographically, this system is the standard language everyone uses to report what you see.
Score the tibial component first: add up radiolucent line widths across all zones. A total below 5 mm that is not progressing can be watched. A score of 5–9 mm warrants serial films. A score of 10 mm or more means the component is failing, whether or not the patient has symptoms yet.
Do not let a reassuring score override what you see on the film. If the component has shifted position compared to prior imaging, that is failure by definition — the score becomes irrelevant.
One limitation worth internalizing: this system cannot detect pure axial subsidence. If a tibial tray is sinking straight down without rotating, angular measurements will look normal. Serial film comparison and careful attention to joint line position are the only ways to catch this.