Achieving Safe Zone Cup Positioning in Total Hip Arthroplasty using Anatomical Landmarks: A Prospective Computed...

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Accurate acetabular component orientation in total hip arthroplasty (THA) is essential for restoring hip biomechanics and preventing complications.
• Computer-assisted navigation improves accuracy but faces limitations in cost and availability.
• Anatomical landmarks, specifically the anterior acetabular notch (AAN) and transverse acetabular notch (TAN), offer potential as reliable intraoperative guides.

Purpose of the Study:

• To evaluate the accuracy of acetabular cup placement in THA using the AAN and TAN as intraoperative landmarks.
• To compare the accuracy of landmark-guided placement with established safe zones for component orientation.
• To assess the functional outcomes and complication rates associated with this technique.

Main Methods:

• A prospective observational study involving 53 patients undergoing primary THA.
• Intraoperative acetabular component positioning guided by AAN for anteversion and TAN for abduction.
• Post-operative computed tomography (CT) assessment of cup orientation at 14 days.
• Evaluation of functional outcomes using the Harris Hip Score (HHS).

Main Results:

• Mean post-operative abduction was 40.13° and anteversion was 16.29°, both within Lewinnek's safe zones.
• Significant improvement in HHS from 37.42 preoperatively to 85.83 postoperatively.
• Markedly reduced mean error in cup positioning and no dislocations or major complications observed.

Conclusions:

• Simple anatomical landmarks (AAN and TAN) provide a reliable method for acetabular cup placement in THA.
• This landmark-based approach is a cost-effective alternative to navigation systems.
• The technique yields comparable clinical outcomes to technology-assisted methods.