What are the recommended tips and pearls for properly reaming and placing the acetabular cup during a total hip replacement?

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Acetabular Reaming and Cup Placement Technique for Total Hip Replacement

I must note that the provided evidence focuses primarily on femoral canal preparation and cemented hemiarthroplasty, not acetabular reaming and cup placement. However, I can provide guidance based on the limited acetabular-specific research available and general surgical principles.

Key Technical Pearls for Acetabular Preparation

Sequential Reaming Approach

Start with the largest reamer that fully seats in the native acetabulum without anteroposterior translation between the walls, then proceed sequentially. This single-reamer or minimal-reamer technique has demonstrated 99.7% successful osseointegration at 1 year in 740 hips, with no intraoperative acetabular fractures 1. This approach is more efficient than traditional multiple-reamer progression and is safe when applied to hips with normal acetabular morphology.

Important caveat: Approximately 11% of hips with significant acetabular deformity cannot accommodate this technique and require traditional sequential reaming 1.

Anatomic Landmarks for Cup Positioning

Use the acetabular fossa as your primary guide for anticipated cup inclination:

  • The most medial aspect of the acetabular sourcil (roof) correlates closely with the central axis of the acetabular cup at the target inclination of 40° ± 5° 2
  • The transverse acetabular ligament provides reliable guidance for anteversion, though visualization may be obscured by instruments 3
  • Consider marking "channel lines" along the transverse acetabular ligament before instrument placement to maintain visual reference 3

Direction-Specific Reaming Pattern

Concentrate reaming posteriorly, minimize anterosuperior reaming:

  • Simulated reaming analysis shows the smallest bone removal at 1 o'clock position (64 ± 45 mm²) and largest at 8 o'clock position (137 ± 73 mm²) 4
  • This posterior concentration is particularly important in mild developmental dysplasia of the hip 4
  • Anterosuperior preservation helps maintain bone stock and reduces fracture risk

Target Cup Position

Aim for 40° inclination and 20° anteversion as the standard starting point, adjusting for:

  • Lateral pelvic tilt (assess clinically or radiographically before final placement) 5
  • Patient-specific anatomy using the transverse acetabular ligament for version control 3
  • All four cups placed using smartphone-assisted technique achieved Lewinnek safe zone positioning (41-47° inclination) 5

Medialization Strategy

Use the acetabular fossa as your depth guide:

  • Ream to the true acetabulum, using the fossa as your anatomic reference for appropriate medialization 6
  • Avoid excessive medialization that compromises bone stock
  • In protrusio cases, consider bone grafting before final reaming 6

Critical Safety Considerations

When NOT to Use Single-Reamer Technique

Exclude this approach in:

  • Significant acetabular deformity (approximately 11% of cases) 1
  • Severe dysplasia requiring structural reconstruction
  • Revision cases with bone loss
  • Protrusio acetabuli requiring grafting

Supplemental Fixation

Plan for screw fixation in only 3% of cases with normal anatomy 1:

  • 714 of 739 cups (96.6%) achieved stable press-fit without screws
  • Reserve screws for inadequate initial stability or poor bone quality
  • One cup (0.1%) developed stable fibrous fixation without requiring revision 1

Practical Workflow

  1. Assess acetabular morphology preoperatively to determine if single-reamer technique is appropriate
  2. Identify and mark the transverse acetabular ligament early for version reference
  3. Select the largest reamer that seats fully without translation
  4. Ream concentrating posteriorly (7-9 o'clock positions), preserving anterosuperior bone
  5. Use acetabular fossa to guide depth and inclination
  6. Verify position using marked anatomic landmarks before final impaction
  7. Assess stability - if inadequate, consider supplemental screw fixation

Common Pitfalls to Avoid

  • Over-reaming anterosuperiorly: This removes critical bone stock without improving stability 4
  • Losing anatomic landmarks: Mark the transverse acetabular ligament before instruments obscure visualization 3
  • Ignoring pelvic tilt: Failure to account for lateral pelvic tilt results in malposition 5
  • Routine use of screws: Only 3% of well-prepared acetabula require supplemental fixation 1

Note: The majority of provided evidence addressed femoral preparation for cemented hemiarthroplasty rather than acetabular preparation for THA. The recommendations above are based on the limited acetabular-specific research available 1, 6, 3, 2, 4, 5.

References

2
Research

Using acetabular fossa as a guide for anticipated inclination of uncemented cup in total hip replacement.

International journal of clinical and experimental medicine, 2015

6
Research

A Systematic and Anatomic Approach to Acetabular Preparation During Total Hip Arthroplasty.

Bulletin of the Hospital for Joint Disease (2013), 2021

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.