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.
|1999||Buschmann MD, Kim Y-J, Wong M, Frank E, Hunziker EB, Grodzinsky AJ. Stimulation of aggrecan synthesis in cartilage explants by cyclic loading is localized to regions of high interstitial fluid flow1. Arch Biochem Biophys. June 1, 1999;366(1):1-7.|
|1982||Armstrong CG, Mow VC. Variations in the intrinsic mechanical properties of human articular cartilage with age, degeneration, and water content. J Bone Joint Surg. 1982;64A(1):88-94.|
|1995||Dalstra M, Huiskes R, van Erning L. Development and validation of a three-dimensional finite element model of the pelvic bone. J Biomech Eng. August 1995;117(3):272-278.|
|1994||Ateshian GA, Lai WM, Zhu WB, Mow VC. An asymptotic solution for the contact of two biphasic cartilage layers. J Biomech. November 1994;27(11):1347-1360.|
|1995||Ateshian GA, Wang H. A theoretical solution for the frictionless rolling contact of cylindrical biphasic articular cartilage layers. J Biomech. November 1995;28(11):1341-1355.|
|1941||Biot MA. General theory of three‐dimensional consolidation. J Appl Phys. February 1941;12(2):155-164.|
|1983||Brown TD, Shaw DT. In vitro contact stress distributions in the natural human hip. J Biomech. 1983;16(6):373-384.|
|1972||Simon SR, Radin EL, Paul IL, Rose RM. The response of joints to impact loading, II: in vivo behavior of subchondral bone. J Biomech. May 1972;5(3):267-272.|
|1983||Ahmed AM, Burke DL. In-vitro of measurement of static pressure distribution in synovial joints, I: tibial surface of the knee. J Biomech Eng. August 1983;105(3):216-225.|
|1989||Proctor CS, Schmidt MB, Whipple RR, Kelly MA, Mow VC. Material properties of the normal medial bovine meniscus. J Orthop Res. November 1989;7(6):771-782.|
|1993||Keyak JH, Fourkas MG, Meagher JM, Skinner HB. Validation of an automated method of three-dimensional finite element modelling of bone. J Biomed Eng. November 1993;15(6):505-509.|
|1962||McCutchen CW. The frictional properties of animal joints. Wear. January–February 1962;5(1):1-17.|
|1980||Fukubayashi T, Kurosawa H. The contact area and pressure distribution pattern of the knee: a study of normal and osteoarthrotic knee joints. Acta Orthop Scand. December 1980;51(5):871-879.|
|1990||Fithian DC, Kelly MA, Mow VC. Material properties and structure-function relationships in the menisci. Clin Orthop Relat Res. March 1990;252:19-31.|
|1986||Radin EL, Rose RM. Role of subchondral bone in the initiation and progression of cartilage damage. Clin Orthop Relat Res. December 1986;213:34-40.|
|1998||Soltz MA, Ateshian GA. Experimental verification and theoretical prediction of cartilage interstitial fluid pressurization at an impermeable contact interface in confined compression. J Biomech. October 1998;31(10):927-934.|
|1980||Mow VC, Kuei SC, Lai WM, Armstrong CG. Biphasic creep and stress relaxation of articular cartilage in compression: theory and experiments. J Biomech Eng. February 1980;102(1):73-84.|
|1976||Woo SL-Y, Akeson WH, Jemmott GF. Measurements of nonhomogeneous, directional mechanical properties of articular cartilage in tension. J Biomech. 1976;9(12):785-791.|
|1998||Carey JPR. The Compressive Characteristics of the Glenoid Labrum [Master's thesis]. Queen's University; January 1998.|
|1994||Athanasiou KA, Agarwal A, Dzida FJ. Comparative study of the intrinsic mechanical properties of the human acetabular and femoral head cartilage. J Orthop Res. May 1994;12(3):340-349.|
|1996||Merz B, Niederer P, Müller R, Rüegsegger P. Automated finite element analysis of excised human femora based on precision-QCT. J Biomech Eng. August 1996;118(3):387-390.|
|1992||Bigliani LU, Pollock RG, Soslowsky LJ, Flatow EL, Pawluk RJ, Mow VC. Tensile properties of the inferior glenohumeral ligament. J Orthop Res. March 1992;10(2):187-197.|
|1990||Kuhn JL, Goldstein SA, Feldkamp LA, Goulet RW, Jesion G. Evaluation of a microcomputed tomography system to study trabecular bone structure. J Orthop Res. 1990;8(6):833-842.|
|1999||Liao H, Belkof SM. A failure model for ligaments. J Biomech. 1999;32(2):183-188.|
|1993||Bergmann G, Graichen F, Rohlmann A. Hip joint loading during walking and running, measured in two patients. J Biomech. August 1993;26(8):969-990.|