The Posterior Capsular Ligamentous Complex Contributes to Hip Joint Stability in Distraction

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Anatomy

Background:

• Soft tissue laxity post-total hip arthroplasty (THA) is linked to accelerated wear and dislocation.
• Understanding capsular and rotator cuff contributions to hip stability is crucial for THA outcomes.

Purpose of the Study:

• To quantify the impact of anterior and posterior capsular complexes and short external rotators on hip stability during axial traction.
• To assess the role of these structures in preventing dislocation and wear after THA.

Main Methods:

• Cadaveric hip joints (n=12) were used to simulate anterior and posterior surgical approaches.
• Sequential resection of capsular and short external rotator tissues was performed.
• Hip joint distraction was measured under a 250 N axial traction force.

Main Results:

• Anterior capsular resection significantly increased hip joint distraction (4.0 to 14.5 mm).
• Posterior capsular resection also significantly increased distraction (6.0 to 11.4 mm, then to 20.5 mm).
• Short external rotator resection had a less significant impact on distraction compared to capsular resection.

Conclusions:

• The posterior capsule, alongside the anterior capsule, is vital for maintaining hip joint stability against distraction.
• Preserving both capsular complexes is essential for minimizing instability and potential complications after THA.