Function of the ligamentum teres in limiting hip rotation: a cadaveric study.

PURPOSE

The purpose of this cadaveric study was to evaluate the function of the ligamentum teres (LT) in limiting hip rotation in 18 distinct hip positions while preserving the capsular ligaments.

METHODS

Twelve hips in 6 fresh-frozen pelvis-to-toes cadaveric specimens were skeletonized from the lumbar spine to the distal femur, preserving only the hip ligaments. Hip joints were arthroscopically accessed through a portal located between the pubofemoral and iliofemoral ligaments to confirm the integrity of the LT. Three independent measurements of hip internal and external rotation range of motion (ROM) were performed in 18 defined hip positions of combined extension-flexion and abduction-adduction. The LT was then arthroscopically sectioned and rotation ROM reassessed in the same positions. A paired sample t test was used to compare the average internal and external hip rotation ROM values in the intact LT versus resected conditions in each of the 18 positions. P < .0014 was considered significant.

RESULTS

A statistically significant influence of the LT on internal or external rotation was found in 8 of the 18 hip positions tested (P < .0014). The major increases in internal and external rotation ROM occurred when the hip was in 90° or 120° of flexion.

CONCLUSIONS

The major function of the LT is controlling hip rotation. The LT functions as an end-range stabilizer to hip rotation dominantly at 90° or greater of hip flexion, confirming its contribution to hip stability.

CLINICAL RELEVANCE

Ruptures of the LT contribute to hip instability dominantly in flexed hip positions.