Advantages:
- The 3D-printed edema ruler provides accurate 1-mm increment markings for quantifiable, reliable measurements
- Standardized pressure application and clear markings yield high intraclass correlation coefficients for both single and average measurements
- Significantly cheaper than equipment-intensive options and the 3D-printed PLA construction ensures consistent dimensions
- Noninvasive and patient-friendly and can be quickly deployed in any clinic setting
Summary:
Lower extremity edema is a common clinical concern, especially in patients with chronic venous disease, but its evaluation is often hampered by the subjective nature of the standard “pitting test.” Inconsistent techniques for applying pressure and varying interpretations of indentation depth lead to considerable interobserver variability, making accurate tracking of edema progression challenging. While alternative quantitative tools exist in theory, they are frequently costly, cumbersome, or impractical for routine clinical use. The result is a persistent need for a cost-effective, user-friendly, and reliable method to measure edema and streamline patient assessments over time objectively.
The 3D-printed edema ruler addresses the subjective nature of traditional pitting tests by providing a standardized, quantitative measurement method: its two-part design - a marked inner tube and a precisely fitting outer slider—enables consistent depth readings after applying uniform pressure above the medial malleolus. Using PLA filament and CAD software, this cost-effective, intuitive system ensures reproducible results and minimizes interobserver variability, making it a novel, objective solution for assessing and monitoring lower extremity edema in clinical settings.
Figure 1: A) Inner tube of the ruler with 1-mm markings on its rounded tip. B) The slider portion of the ruler, fits over the inner tube. C) Assembled edema ruler with slider positioned on inner tube.
Fig 2: A) Finger pressure is applied on the tibia 5 cm above the medial malleolus. B) The resultant pit after 20 seconds of applied pressure (arrow and circle). C) The edema ruler is placed into the pit on the skin. D, The slider is moved to contact the surrounding skin surface.
Desired Partnerships:
- License
- Sponsored Research
- Co-Development