Biomechanical Treatment of Osteoarthritis of the Knee

Abstract

There are basically two types of osteoarthritis: primary, resulting from a lowered resistance of the articular tissues when the load exerted on the knee is physiological, and secondary, from a change of the mechanical stress which overwhelms the resistance to mechanical stress of otherwise normal tissues. In the primary form, with insufficient tissues of the knee, the physiological stress provokes an overall osteoarthritis attacking the femoro-tibial and the patello-femoral joints. It is medial as well as lateral. In its early phase the joint space is narrowed neither in the lateral nor in the medial part of the knee. The dense cups underlying the tibial plateaux remain symmetrical. In secondary osteoarthritis the mechanical stress becomes abnormally high and overtakes the physiological capability of the tissues to resist stress. A permanent displacement of the load R medially, laterally, or posteriorly produces a concentration of the articular compressive stresses which, once localized, can be extremely high. The causes and consequences of displacements of R have been analysed in Chapter V. Any fracture which results in uneven joint surfaces can also concentrate the articular compressive stresses and cause subsequent osteoarthritis. Meniscectomy has the same effect by decreasing the weight-bearing surface of the joint. It is to avoid the inevitable osteoarthritis following meniscectomy that R.J. Furlong and I have sutured in London, a meniscus freshly torn through the area close to its capsular insertion.