Prof Dava Newman 16.423.J/HST515J Space Biomedical Engineering and Life Support 6 Bedrest/Hypokinesia Studies Models for Weightlessness of spaceflight Study Finding References 5-36 Weeks Bedrest 90 healthy young men; 5% loss of calcaneal minera Schneider and each month mechanical and biochemical McDonald. 1984 countermeasures not success ful 120-day Bedrest Mineralization rate slowed; contradictory results Ⅵco,etal.1987 demonstrate difficulties of bedrest as space analog 17-week bedrest 6 healthy young males: 6 months of reambulation; LeBlanc, et al., 1990 BMD change(p <.05 femoral neck(N)-36 trochanter(1-4.6;%/week(p <.05: FN- 21 +/.05 T-, 27+/- 05; Reambulation %recovery: FN 0.00+/- 06, T0.05 +/-05(prox femur did not recover well 370-day Antiorthostatic Highest losses in foot bones remedial measures Zaichick and Morukov, Hypokinesia Test delay osteoporosis but do not completely exclude it; 1998 results obtained by different methods often conflicting
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support 6 Bedrest / Hypokinesia Studies Models for Weightlessness of Spaceflight Study Finding Refere n c es 5-36 Weeks Bedrest 90 healt h y young men; 5% los s of c alcaneal minerla each m onth; mechanical and biochemical counterm easures not suc ces sful S chneider and M cDonald, 1984 120- day B e drest Mineralization r ate slowed; c ontradictor y r e s ults demonstrate difficulties of bedres t as space analog Vico, et al., 1987 17- week B e drest 6 healthy young male s; 6 months of reambulation; BMD % c han ge (p < .05): femoral neck (FN) -3.6, tr o c h a nte r (T) -4.6; % / w e e k (p < . 0 5): FN -. 2 1 +/- . 0 5, T -.27 +/- .05; Reamb ulatio n % recovery: FN 0.00 +/- .0 6, T 0.0 5 +/- . 0 5 (p r ox. fe m ur did n ot re c o v e r w ell) Le Blanc, et al., 1990 3 7 0-d a y A nti orth o static Hyp o kin e sia T e st Highest los ses in foot bones; remedial meas ures delay os teoporosis b ut do not c o m plet ely exclu de it; res ult s obtained by different met hods often conflicting Z aichic k and M oru k o v, 1998
Prof Dava Newman 16.423.J/HST515J Space Biomedical Engineering and Life Support Summary of Findings Significant bone loss in weightlessness Calcium excretion increases- negative balance Bone mineral density decreases weight bearing areas: 1-2% per month Osteoblast(builders) proliferation and activity reduced, while osteoclasts(consumers)appear to be unaffected Fracture repair may be impaired Bone strength is reduced
Prof. Dava Newman 16.423J/HST515J Space Biomedical Engineering and Life Support 7 Summary of Findings ò Significant bone loss in weightlessness ò Calcium excretion increasesœ negative balance ò Bone mineral density decreases œ weight bearing areas: 1-2% per month ò Osteoblast (builders) proliferation and activity reduced, while osteoclasts (consumers) appear to be unaffected ò Fracture repair may be impaired ò Bone strength is reduced