Objective:

To propose a reproducible method for measuring overhang distance (OD) in CT images after multiplanar reformation and to evaluate its impact on iliopsoas impingement (IPI) in patients undergoing primary total hip arthroplasty (THA), highlighting its clinical significance.

Key Findings:

• Cup overhang (CO) can lead to iliopsoas impingement (IPI), with an incidence of 2-7% in THA patients, emphasizing the need for accurate measurement.
• No standardized method for measuring overhang distance (OD) exists, impacting the assessment of IPI risk.
• The proposed MPR method for measuring OD may provide more accurate assessments compared to previous methods, potentially improving patient outcomes.

Interpretation:

The study highlights the need for standardized measurement techniques for OD in THA to better understand and mitigate the risk of IPI.

Limitations:

• Single-center study may limit generalizability.
• Retrospective design may introduce selection bias and affect data accuracy.
• Exclusion of certain patient groups could affect findings.

Conclusion:

Standardized measurement of cup overhang using MPR may enhance the understanding of its association with iliopsoas impingement in THA patients.