Congruency Effects on Load Bearing in Diarthrodial Joints

Abstract

Modelling load bearing in diarthrodial joints is challenging, due to the complexity of the materials, the boundary and interface conditions and the geometry. The articulating surfaces are covered with cartilage layers that are filled with a fluid that plays a major role in load bearing [Mow, V.C., Holmes, M.H., Lai, W.M. (1984) "Survey article: fluid transport and mechanical properties of articular cartilage: a review", Journal of Biomechanics 17(5), 377-394]. Researchers have tended to approximate joint geometry using axisymmetry [Donzelli, P.S., Spilker, R.L., Ateshian, G.A., Mow, V.C. (1999) "Contact analysis of biphasic transversely isotropic cartilage layers and correlations with tissue failure", Journal of Biomechanics 32, 1037-1047], often with a rounded upper articulating surface, creating a form of Hertz problem [Donzelli, P.S., Spilker, R.L., Ateshian, G.A., Mow, V.C. (1999) "Contact analysis of biphasic transversely isotropic cartilage layers and correlations with tissue failure", Journal of Biomechanics 32, 1037-1047]. However, diarthrodial joints (shoulder, hip and knee) are equipped with peripheral structures (glenoid labrum, acetabular labrum and meniscus, respectively) that tend to deepen the joint contact and thus cause initial contact to be established at the periphery of the joint rather than "centrally". The surface geometries are purposefully incongruent, and the incongruency has a significant effect on the stresses, pressures and pressure gradients inside the tissue. The models show the importance of the peripheral structures and the incongruency from a load-bearing perspective. Joint shapes must provide a compromise between demands for load-bearing, lubrication and the supply of nutrients to the chondrocytes of the cartilage and cells of the peripheral structures. Retention and repair of the functionality of these peripheral structures should be a prime consideration in any surgical treatment of an injured joint.

Relationship between increased in vivo meniscal loads and abnormal tibiofemoral surface alignment in ACL deficient sheep is varied

“…We also acknowledge that all kinetic measures, including "Intact" measures, were reproduced at 20w post-injury. It is possible that the material properties and geometries of the remaining tissues changed over time in response to mechanical and biological perturbations of the stifle milieu (Frank, et al, 2004;Funakoshi, et al, 2007;Mow, et al, 2005;Ochi, et al, 1997). This could mean that Intact and 4w meniscal force measures may not reflect the earlier time point function exactly.…”

“…Many have hypothesized that loads borne by the remaining structures of the knee are different following ACL tear (Frank, et al, 2004). By and large, in vitro (Allen, et al, 2000;Papageorgiou, et al, 2001) and numerical (Li, et al, 2002) studies have provided significant evidence to support the hypothesis.…”

“…In vitro robotic studies in particular have demonstrated that the medial collateral ligament (MCL) and menisci function as secondary restraints to anterior tibial translation during a simulated motion path (Allen, et al, 2000;Kanamori, et al, 2000). Menisci also play a critical role in distributing contact stress uniformly between the tibiofemoral surfaces of the knee (Shrive, et al, 1978) and in modulating fluid flow within the load-bearing cartilage regions (Adeeb, et al, 2004). Thus impaired meniscal function is likely to result in joint instability and damage to the underlying articular cartilage (Englund and Lohmander, 2004).…”

Concurrent Criterion-Related Validity of Physical Examination Tests for Hip Labral Lesions: A Systematic Review

“…In another study, Ferguson et al 39 used bovine acetabular labrums and again reported the labrum's ability to maintain interstitial fluid and resist the flow of fluid out of the cartilage with compression testing. Adeeb et al 40 noted that the function of the labrum is to reduce the pressure gradient and fluid flow out of the joint tissues thereby decreasing the tensile stresses across the joint's contact areas. Adeeb et al 40 also suggested decreased circumferential stresses at the joint's perimeter are due to the labrum's function of confining the joint.…”

“…Adeeb et al 40 noted that the function of the labrum is to reduce the pressure gradient and fluid flow out of the joint tissues thereby decreasing the tensile stresses across the joint's contact areas. Adeeb et al 40 also suggested decreased circumferential stresses at the joint's perimeter are due to the labrum's function of confining the joint. Jones 41 noted that both the labrum and joint capsule have important functions of stabilizing the joint by creating a vacuum seal.…”