[Radiological study on the cup abduction angle during total hip arthroplasty]

Area of Science:

• Orthopedic Surgery
• Radiology
• Biomedical Engineering

Background:

• Total hip arthroplasty (THA) requires precise acetabular component placement for optimal outcomes.
• Controlling the acetabular abduction angle is critical for stability and function post-THA.
• Identifying reliable anatomical markers for acetabular positioning is essential in THA surgery.

Purpose of the Study:

• To analyze the relationship between various parameters measured on anteroposterior (AP) X-rays after THA.
• To identify reliable anatomical markers and reference standards for acetabular placement in THA.
• To accurately control the abduction angle of the acetabulum during THA surgery.

Main Methods:

• Postoperative AP X-rays of 157 hips from 128 patients undergoing THA were analyzed.
• Measurements included abduction angle (β), ilium thickness (a), acetabular cup insertion depth (b, d), and ischial thickness (c).
• Correlations and linear relationships between these parameters were statistically evaluated.

Main Results:

• A positive correlation was observed between abduction angle (β) and cup insertion depth (b) (r=0.424, P=0.000).
• A negative correlation was found between abduction angle (β) and inferior cup depth (d) (r=-0.407, P=0.000).
• Linear relationships were established between abduction angle (β) and the ratios b/a (t=5.753, P=0.000) and d/c (t=-6.671, P=0.000).

Conclusions:

• The abduction angle in THA is primarily influenced by the distance from the outer cup edge to the inferior portion (d).
• The distance from the outer cup edge (b) can serve as a valuable reference for controlling acetabular abduction during surgery.
• Accurate control of these parameters aids in achieving optimal acetabular positioning in total hip arthroplasty.