[Postsurgical computed tomography of uncemented hip arthroplasty]

Area of Science:

• Orthopedic surgery
• Radiology
• Biomedical engineering

Background:

• Assessing the stability of uncemented femoral stems after surgery is crucial for patient outcomes.
• Loosening of these implants can lead to pain and revision surgery.
• Accurate diagnostic methods are needed to evaluate bone-prosthesis integration.

Purpose of the Study:

• To evaluate the diagnostic value of postsurgical computed tomography (CT) for detecting loosening of uncemented femoral stems.
• To compare CT imaging results with direct measurements of bone-prosthetic stem contact.

Main Methods:

• Six femora with implanted uncemented stems were scanned using incremental and spiral CT after embedding in polymethylmethacrylate.
• The femora were then sectioned, and the bone-prosthetic stem contact areas were measured.
• CT-derived contact measurements were compared with the actual sectioned data.

Main Results:

• CT imaging underestimated the bone-prosthetic stem contact compared to direct sectioning.
• Contact measurements varied significantly, with differences up to 24% between CT and section data.
• A low correlation (r = 0.61) was observed between CT results and actual contact areas.

Conclusions:

• Standard single-slice or two-slice CT is insufficient for accurately assessing direct bone-endoprosthesis contact.
• Multidetector row CT (MDCT) may offer improved accuracy for measuring femoral stem cortical contact.
• Further research with MDCT is warranted to validate its efficacy in diagnosing stem loosening.