Measuring femoral neck loads in healthy young and older adults during stair ascent and descent

Abstract

Understanding the hip loading environment for daily activities is useful for hip fracture prevention, rehabilitation, and the design of osteogenic exercises. Seventeen older adults (50–70 yrs) and twenty young adults (18–30 yrs) were recruited. A rigid body model combined with a musculoskeletal model was used to estimate lower extremity loading. An elliptical cross-section model of the femoral neck was used to estimate femoral neck stress during stair ascent and descent. Two peaks were identified in the stress curves, corresponding to the peaks in the vertical ground reaction force. During stair ascent, significantly higher tension on the superior femoral neck was found for the young group at peak 1 (young: 13.5±6.1 MPa, older: 4.2±6.5 MPa, p<0.001). Also during stair ascent, significantly higher compression on the posterior femoral neck was found for the older group at peak 2 (young: -11.4±4.9 MPa, old: -18.1±8.6 MPa, p = 0.006). No significant difference was found for stair descent. Components of stress (muscle vs. reaction forces; axial forces vs. bending moments) were also examined for each trial of stair ascent and descent. The stresses and their components provided loading magnitude and locations of higher stress on the femoral neck during stair ascent and descent. Understanding femoral neck stresses may be used to help prevent hip fractures, reduce pain, improve rehabilitation, and design osteogenic exercises.

Effect of gait types and external weight carrying strategies on the femoral neck strains during stair descent

“…According to the previous work, greater stresses/strains were found during stair descent than stair ascent for the femoral neck region [24,25], which may result in more hip/femoral pain and pain related falls [10][11][12][13][14][15]. More protective strategies (change gait types, weight carrying strategies etc.)…”

“…But the effect of co-contracting muscles, the geometry and material properties of the bone were not considered in the analysis. The 2-dimensional simplified model was utilized for stair ascent and descent to estimate normal stress on the certain cross-sections of the femoral neck [24,25]. But this simplified model could not estimate the 3-dimensional strains to represent the deformation of the structure.…”