Non-invasive (pQCT) biomechanical analysis of the musculoskeletal system in chronically dialysed patients.

SARA FELDMAN; IRENE GRAPPIOLO; RICARDO FRANCISCO CAPOZZA; GUSTAVO ROBERTO COINTRY; GABRIEL INCHAUSPE; BEATRIZ RADICE; PAOLA REINA; SERGIO CASTELLINI; GRISELDA NICOLA; FAVIO ACOSTA; JOSÉ LUIS FERRETTI

Colonia (Alemania)

Workshop; VI INTERNATIONAL WORKSHOP FOR MUSCULOSKELETAL & NEURONAL INTERACTIONS; 2008

International Society of Musculoskeletal & Neuronal Interactions (ISMNI)

NON-INVASIVE (pQCT) BIOMECHANICAL ANALYSIS OF THE MUSCULOSKELETAL SYSTEM IN CHRONICALLY DIALYSED PATIENTS. Feldman S, Grappiolo I, Capozza R, Cointry G, Inchauspe G, Radice B, Reina P, Castellini P, Nicola G, Acosta F, Ferretti JL. Univ Hospital & Faculty of Medicine, Natl Univ of Rosario, Argentina.       Assessment of musculoskeletal status in chronically dialised patients is important because they are affected by both metabolic and mechanical determinants of the integrity of their bones. Despite of the wide etiological diversity and pathological complexity of renal osteodistrophy, it can be proposed that a tomographical description of bone and muscle scans in those patients may allow describing some typical patterns of affectation in men and women.     With that purpose, we determined indicators of bone mass (total, trabecular and cortical BMC; total and trabecular vBMD; cortical CSA), tissue mineralization (cortical vBMD corrected from the partial-volume effect as per Rittweger et al [JMNI 4:436,2004], Rho-vCtD), cross-sectional design (endosteal perimeter, EoPm; cortical thickness; bending and torsion moments of inertia, CSMI’s) and strength (bending and torsion Bone Strength Indices, BSI’s; Stress-Strain Index, SSI), and of muscle strength (muscle CSA) in tibial (4, 14, 38, and 66% sites) and radial (4 and 66% sites) pQCT scans of 21 men and 14 women aged 15-66 years under chronic hemodialysis (HD). Suitable Z-scores of these data were then calculated with reference to 260 healthy adults (60 men, 80 pre-MP women, 120 post-MP women) of comparable age. Time on dialysis and serum PTH activity were also analyzed.     The dialytical condition reduced trabecular BMC and vBMD in men and women. Cortical BMC, CSA and thickness, the BSIs and the SSI were less affected. In general terms, bone mass loss was greater in women than men. EoPm was increased, thus the impairment in CSMIs was relatively mild in general, and only significant in women. No changes were observed in cortical Rho-vCtD. The classical, hyperbolic relationships between the CSMIs (y) and Rho-vCtD (x) (“distribution/quality” curves, regarded as descriptive of the functional status of the bone mechanostat in the cortices) showed lower ordinates than normal only in the women. Muscle mass was generally reduced, especially in the women. Bone mass (but not CSMIs) per unit of muscle mass decayed, more severely in the women. These changes were significant only in the tibial, not the radial scans. The magnitude of all the described changes was correlated significantly with both serum PTH activity and time on dialysis.     Results show that 1. the HD-induced metabolic osteopenia was more severe in metaphyseal regions with thin cortices than in bone diaphyses, and predominantly so in the women; 2. the cortical loss was predominantly endosteal, with little effect on the CSMIs, and practically no increase in cortical mineralization; 3. the mechanical orientation of bone modeling by bone mechanostat as a function of mechanical usage (as assessed by the CSMI/Rho-vCtD ratio) seemed to have been affected only in women, perhaps reflecting some metabolic (not mechanical) disturbances, and 4. the magnitude of bone loss was metabolically associated to PTH activity and time on dialysis.     Predominance of effects in the legs may be associated with stroll-related problems. The gender-related differences are attributable to hormonal factors.