Femoral neck bone mineral density in ambulatory men with poliomyelitis

Abstract

We evaluated bilateral femoral neck bone mineral densities (FNBMDs) in 32 men with poliomyelitis and their matched controls. Men with poliomyelitis had significantly lower FNBMD in both legs, and FNBMD was lowest in their shorter legs. Knee extensor strength and regular exercise were important predictive factors associated with decreased FNBMD. People with poliomyelitis (polio) are prone to leg fractures after mild trauma. The flaccid paralysis, asymmetric involvement, and underdeveloped growth of afflicted legs may lead to osteoporosis of either leg, characterized by different patterns. This study aimed to measure their femoral FNBMD and to explore the factors associated with changes in FNBMD in either leg. We did a prospective study to evaluate bilateral FNBMD with dual-energy X-ray absorptiometry in 32 men with polio (age range, 41-57years; mean, 47years) and 32 age- and body mass index-matched controls. Measuring the difference in leg length, we classified the legs of each polio subject as "longer" or "shorter." In addition, we chose the right leg of each control as a reference leg. We then used the Mann-Whitney U test to compare FNBMD of these three groups of legs and searched for the factors associated with FNBMD using stepwise multiple regression analyses. Compared to the reference leg, men with polio had significantly lower FNBMD in both their longer and shorter legs, by 13% and 23%, respectively. The difference in FNBMD between the two legs of polio subjects was significant. Knee extensor strength and regular exercise were two important factors associated with bilateral FNBMD in men with polio. Men with polio had lower bilateral FNBMD. FNBMD of the shorter leg should be the choice for predicting the risk of hip fracture in men with polio because on average, the shorter leg has lower BMD.