Biomechanica Hungarica VI. évfolyam, 1. szám 249 FINITE ELEMENT ANALYSIS OF WEIGHTBATH HYDROTRACTION TREATMENT IN THE CASE OF OSTEOPOROSIS Márta Kurutz 1 , László Oroszváry 2 1 Budapest University of Technology and Economics 2 Knorr Bremse Hungaria Ltd kurutzm@eik.bme.hu Abstract 3D finite element analysis of the first elastic period of the weightbath hydrotraction treatment is presented to analyze the effect of osteoporosis during the traction procedure. A systematic parameter analysis of the material moduli of the aging spinal motion segment with osteoporotic bone was investigated. It was concluded that the osteoporosis in itself can not be a contraindicating factor of weightbath hydrotraction treatment. However, if applying extra weigts, beside the quality of bone and the grade of osteoporosis, the age of patients, their body structure and body weight must be carefully considered as well. Keywords: weightbath hydrotraction treatment, lumbar spinal motion segment, indirect and direct traction, elongation of disc, osteoporosis Introduction A large percent of population is affected by low back pain, starting from the degeneration of lumbar spinal structures. In some cases, traction might be the effective treatment. Weightbath hydrotraction therapy (WHT) is a method of hydro- or balneotherapy where the patient is suspended in water, loaded by extra weights applied on certain points of the body, to stretch the different parts of the spinal column or lower limbs. The weightbath hydrotraction method, its indications, contraindications, and clinical effects, its application, equipment and the biomechanics of it were detailed in. 1 However, the question has not been answered yet that what is the relation between WHT and osteoporosis, or rather, is it possible to apply the treatment for strongly osteoporotic patients? In this study a systematic parameter-analysis is used for the analysis of the mutual effect of the different material moduli of the components of the lumbar motion segment and the vertebral cancellous bone during the special loading conditions of the traction under the water. Although finite element (FE) simulations are increasingly applied to examine the mechanical behaviour of healthy or degenerated spine or the effects of surgical treatments; as far as authors know, FE analyses of the weightbath-like underwater traction treatment can not be found in the literature except for 2 where 3D finite element models (FEM) of human lumbar functional spinal units (FSU) were used for the numerical analysis of weightbath hydrotraction therapy (WHT) in the case of healthy and degenerated lumbar spine. In this study the FE model developed in 2 has been extended to the analysis of WHT applied for osteoporotic lumbar spine.