Ligamentum teres: a functional description and potential clinical relevance

Area of Science:

• Orthopedic biomechanics
• Hip joint anatomy and function

Background:

• The ligamentum teres is a intra-articular ligament of the hip.
• Its role in hip stability is not fully understood.
• Complete ruptures of the ligamentum teres can occur.

Purpose of the Study:

• To investigate the biomechanical role of the ligamentum teres in hip stability.
• To correlate arthroscopic findings of ligamentum teres rupture with patient-reported instability.
• To relate clinical findings to a biomechanical model of hip stability.

Main Methods:

• A string model was developed to simulate ligamentum teres excursion during hip movement.
• Retrospective review of 350 hip surgeries identified 20 cases of complete, unrepaired ligamentum teres rupture.
• Follow-up assessments included clinical evaluation of instability symptoms.

Main Results:

• The biomechanical model showed maximal ligamentum teres excursion in external rotation/flexion (ER/FLEX) and internal rotation/extension (IR/EXT) hip positions.
• All 20 subjects with rupture exhibited laxity during dynamic impingement testing in ER/FLEX.
• Of 9 available for follow-up, 5 reported instability during squatting (ER/FLEX) or leg crossing (IR/EXT), often associated with osseous risk factors like acetabular insufficiency.

Conclusions:

• The ligamentum teres contributes to hip stability in specific positions (ER/FLEX and IR/EXT).
• Patients with osseous risk factors for hip instability may experience instability in these positions following ligamentum teres rupture.
• Inferior acetabular insufficiency is identified as a risk factor for instability.