Cementing of the hip arthroplasty stem increases load-to-failure force: a cadaveric study

Background and purpose - To date, there is not a single clinical or mechanical study directly comparing a cemented and a cementless version of the same stem. We investigated the load-to-failure force of a cementless and a cemented version of a double tapered stem. Material and methods - 10 femurs from 5 human cadaveric specimens, mean age 74 years (68-79) were extracted. Bone mineral density (BMD) was measured using peripheral quantitative computed tomography. None of the specimens had a compromised quality (average T value 0.0, -1.0 to 1.4). Each specimen from a pair randomly received a cemented or a cementless version of the same stem. A material testing machine was used for lateral load-to-failure test of up to a maximal load of 5.0 kN. Results - Average load-to-failure of the cemented stem was 2.8 kN (2.3-3.2) and 2.2 kN (1.8-2.8) for the cementless stem (p = 0.002). The cemented version of the stem sustained a higher load than its cementless counterpart in all cases. Failure force was not statistically significantly correlated to BMD (p = 0.07). Interpretation - Implanting a cemented version of the stem increases the load-to-failure force by 25%.