Fracture risk associated with a fall according to type of fall among the elderly

The kinetic energy and direction of a fall contribute to the occurrence of fracture. However, the fracture risk associated with different types of fall, different amounts of energy and different landing directions is poorly understood. We recorded all falls and fall-related fractures over 7 years in an aged semi-rural home-dwelling population (n = 980), using intensive fall recording. The falls were classified according to type and place of occurrence into slip falls (SLFs), trip falls (TRFs), other extrinsic falls on the level (OEFs), intrinsic falls on the level (IFs), stair falls (STFs), falls from an upper level (ULFs) and nondefined falls (NDFs) occurring indoors or outdoors. Incidences of falls and fractures were calculated for the whole follow-up period. The population was clinically examined to assess general risk factors of fracture, after which the risk of fracture was determined in the first fall according to the different fall types. Comparison was made with intrinsic falling on the level. The overall incidences of indoor and outdoor falls were 328 (95% CI 314-345) and 198 (186-210) per 1000 person-years (PY), respectively, and those of fractures 23 (19-27) and 11 (8-14) per 1000 PY, respectively. Indoor SLFs, TRFs, OEFs, Ifs, STFs, ULFs and NDFs occurred relatively evenly throughout the study period. The crude and adjusted relative fracture risks were greater in SLFs, OEFs and STFs compared with Ifs. Indoor falls and fractures are more common than those occurring outdoors in aged home-dwelling persons. The kinetic energies produced in SLFs, OEFs and STFs may be higher than those generated in Ifs, leading to increased risk of fracture.