Reliability of lower extremity alignment measurement using radiographs and PACS

Area of Science:

• Orthopaedic Surgery
• Radiology
• Medical Imaging Analysis

Background:

• Accurate lower extremity alignment is crucial for knee cartilage surgery and osteotomy.
• Traditionally, alignment is measured using standing hip to ankle radiographs on hard copies.
• Digital radiography and Picture Archiving and Communication Systems (PACS) offer new methods for these measurements.

Purpose of the Study:

• To compare the intra- and inter-observer reliability of lower limb alignment measurements from hard copy radiographs versus digital images using the Philips Easy Vision system.
• To assess the subjective ease of use between hard copy and PACS methods.

Main Methods:

• A retrospective review of 42 patients' standing hip to ankle radiographs.
• Four raters (2 radiologists, 2 orthopaedic surgeons) performed measurements on hard copy and digital images on two separate occasions.
• Measurements included tibial plateau width, weight-bearing line distance to the tibial plateau, and mechanical axis.

Main Results:

• High intra-class correlation coefficients (ICC) were observed for both methods, with PACS generally showing higher reliability.
• Inter-rater reliability for PACS ranged from 0.98 to 0.99, compared to 0.87 to 0.98 for hard copies.
• Physicians found PACS significantly easier to use (P=0.03).

Conclusions:

• PACS software provides higher inter- and intra-observer reliability for evaluating lower extremity alignment compared to traditional hard copy radiographs.
• PACS is now utilized for pre- and post-operative alignment and weight-bearing line assessment in knee surgeries.