Effect of the physiological angular position of the resting knee on pressure at the heel/surface interface.

OBJECTIVE: Heel bedsore is frequent in population motionless more than 50years old. The score of risk of bedsore do not take into account the biomechanical factor, as the flessum of knee. The main objective of this study is to evaluate the relationship between the angle of knee flexion in a supine position with joint relaxation and the maximum interface pressure at the heel area.

MATERIAL/PATIENTS AND METHODS: This study is a cohort with one investigator center, which is in MPR department, CHU de Nîmes. The inclusion criteria are ummper age or 50year-old equal, possibility to stay in decubitus, no bedsore. The study consists of a photographic picture, after cutaneous marking, to assess angle of knee flessum, by two different operators and a measure of the pressure in heel area two consecutive days to assess reproducibility inter- et intra-operator. The concordance of knee angle measure and interface pressure of knee area is studying with coefficient of correlation of Pearson.

RESULTS: Sixty-five patients are included. The reproductibility of the mesure of knee flessum by operators is good (general coefficient of correlation and intra class in 0.89). There is a linear correlation between maximum interface pressure at the heel area and angle of knee flexion if the flessum is between 8° and 20° (0.76). Except theses values, there is no statistical correlation.

DISCUSSION-CONCLUSION: In this population, the knee flessum could be considered as a risk factor of heel bed sore, in particular during medical situations in which there are other known risk factor. It would seem interesting to implement scales with these type of specific risk factor in this type of population, including when people is in air mattress which don't have any prevention in the heel area.