The goal of this research was to determine the functional role of the acetabular labrum in the normal hip joint, and its possible role in the development of osteoarthrosis. Despite clinical evidence of a link between labrum pathology and osteoarthrosis, there have been few studies of the function of the acetabular labrum.

An investigation of the tensile and compressive material properties of labrum tissue showed that the labrum, with its highly oriented collagen fibre structure, was much stiffer and stronger than the adjoining cartilage. The resistance to fluid flow through the labrum was also higher than through cartilage. One can infer that the strength and impermeability of the labrum enhance its ability to seal and stabilise the hip joint.

Poroelastic finite-element models of the hip joint demonstrated that the labrum could seal a pressurised fluid layer within the hip joint under physiological loading. Consequently, cartilage stresses and contact pressures were reduced. The models also indicated that, with its low permeability, the labrum added an important resistance to the flow path for fluid expressed from the cartilage layers. Cartilage stresses and strains calculated by the model were up to 30% higher following removal of the labrum. Contact pressures, and hence friction between the cartilage surfaces, were also significantly higher following labrum removal.

The predictions of the finite-element models were evaluated through a series of in vitro whole-joint creep consolidation experiments on human hips. The overall compression of the cartilage layers under a variety of static and dynamic loads was measured. Removal of the labrum resulted in a quicker cartilage consolidation rate. Peak intra-articular fluid pressures of over 500 kPa were measured during loading in joints with a well-formed labrum. The results of the experiments agreed with the predictions of the finite element models and lend further support to hypotheses about labrum sealing.