The HPC-device: a method to quantify the heel pad shock absorbency.

Previous studies have indicated that the shock absorbency of the heel pad is significant in the pathophysiology of pain conditions connected with heel strike. The purpose of this study was to develop a simple clinically usable method for quantification of the heel pad shock absorbency. The results of our efforts was the HPC-device which consists of a fixing device and a transducer. The HPC-device was found suitable in the evaluation of the heel pad force/deformation characteristics. The reproducibility of heel pad deformation was 0.96. Tests of six cadaver heel pads revealed a high correlation between the HPC result and the shock absorbency found by drop tests. In a normal material (200 heel pads), it was found that the shock absorption decreased with age and that men had significantly higher shock absorbency than women. Men also had significantly thicker heel pads than women. However, there was no linear correlation between the thickness of the heel pad and the shock absorbency, although the thinnest heel pads had the lowest shock absorbency. The HPC-device was found clinically usable and will be used in further testing of the significance of heel pad shock absorption for the development of heel strike dependent over-use injuries.