Cup version can be accurately measured on the false profile view radiograph

Area of Science:

• Orthopedic surgery
• Radiology
• Biomedical engineering

Background:

• Measuring cup version on plain radiographs is difficult due to 2D projection and reproducibility issues.
• Accurate assessment of cup version is crucial for total hip arthroplasty outcomes.

Purpose of the Study:

• To evaluate the false profile view (FPV) for measuring radiographic cup version.
• To determine the impact of patient positioning and implant design on FPV measurements.

Main Methods:

• A sawbone model and 80 post-total hip arthroplasty patients (metal-on-polyethylene and metal-on-metal implants) were used.
• Cup angle was measured on FPV at varying pelvic rotations, quantified by the FP/AP ratio.
• Measurements were correlated with standard methods using Einzel-Bild-Roentgen-Analysis (EBRA) software.

Main Results:

• High correlation (R2=0.95) was found in the sawbone model.
• Patient measurements showed good correlation (R2=0.72) within specific pelvic rotation ranges (FP/AP ratio 0.3-0.49).
• No significant differences were observed between metal-on-polyethylene and metal-on-metal implant designs.
• Excellent intra- and inter-observer reliability (ICC 0.98-0.99) was achieved.

Conclusions:

• FPV cup angle measurement provides an accurate method for assessing radiographic cup anteversion.
• Well-defined patient positioning parameters enhance the reliability of FPV measurements.
• FPV is a valuable tool for improving the accuracy of cup version assessment in hip arthroplasty.