The "Empty Merchant Sign" in acute patellar tendon ruptures

Area of Science:

• Radiology
• Orthopedic Surgery
• Medical Imaging

Background:

• Acute patellar tendon ruptures (APTR) require accurate radiographic diagnosis.
• A novel radiographic sign, the "Empty Merchant Sign," is introduced on Merchant view imaging.

Purpose of the Study:

• To evaluate the accuracy, sensitivity, and specificity of the "Empty Merchant Sign" for diagnosing APTR.
• To assess the impact of a brief tutorial on diagnostic performance for trainees and non-trainees.

Main Methods:

• Lateral and Merchant view radiographs of knees with various conditions were assessed by 50 trainees and non-trainees.
• A tutorial on the "Empty Merchant Sign" was administered, followed by reassessment of the images.
• Diagnostic accuracy, sensitivity, specificity, and positive predictive value were calculated and compared.

Main Results:

• The "Empty Merchant Sign" demonstrated high specificity (100%) and positive predictive value (99%) on Merchant views post-tutorial.
• Merchant view accuracy significantly improved to 95.3% after the tutorial, matching lateral view accuracy.
• No significant difference in Merchant view accuracy was observed between trainees and non-trainees.

Conclusions:

• The "Empty Merchant Sign" is a highly sensitive and specific indicator for APTR on Merchant view radiographs.
• Minimal training enables physicians to effectively utilize this sign for APTR diagnosis.