Fractures in an Aging Population of Poliomyelitis Survivors: A Community-Based Study in Olmsted County, Minnesota

Abstract

To determine the incidence of fractures in a cohort of survivors of paralytic poliomyelitis ("polio"). We conducted a population-based retrospective cohort study of residents of Olmsted County, Minnesota, who had an initial diagnosis of polio between 1935 and 1959 and survived the acute illness. A comprehensive medical records-linkage system was used to retrieve all diagnoses of poliomyelitis in residents of the county for the specified 25-year period. For the 277 study subjects, the medical records were searched for the occurrence of fracture from the time of initial diagnosis of polio until death or the most recent clinical contact. All fractures were classified on the basis of type of associated injury and skeletal site of involvement. The influence of polio on the incidence of fractures was evaluated by estimating the cumulative incidence of new fractures after the diagnosis of polio and the standardized morbidity ratio. The relative influence of various factors on the risk of fracture was determined. Of the 277 Olmsted County residents with polio, 87 experienced 161 fractures, and the estimated cumulative incidence of any fracture after 40 years was 48%. The cumulative incidence of any limb fracture was 41% and was less than the expected value of 44% (P = 0.001). Only the risk of distal femoral and proximal humeral fractures was significantly higher than that among Olmsted County residents in general. The increased risk seemed to be associated with weakness and disuse of the involved limbs rather than with generalized osteoporosis. Theoretically, a greater capacity for bone remodeling in response to changes in muscle use might have protected patients with polio in childhood, but such persons were as likely to sustain a fracture as those with adult-onset poliomyelitis. These data indicate that survivors of paralytic poliomyelitis do not have an unusual risk of fracture except in affected limbs.