[Foot load with different restrictions of knee joint extension]

Dynamic pedobarography has been used for various orthopaedic issues. There is to date a lack of studies describing possible factors of influence with regard to lower limb function.

Ten healthy volunteers were asked to perform a total of six trials (12 left and right steps, data from the right foot) wearing the M.4® ACL/CL knee brace (De Royal Industries, Powell, USA) around the right knee. The limitation ranged from full extension (baseline) to an extension lag of 45 degrees. Peak pressure values were obtained from the hindfoot, midfoot, forefoot and toes with the pedar X system (novel Inc., Munich, Germany). Medians were compared with the two-tailed non-parametric Wilcoxon matched-pairs signed rank test; p-values of less than 0.05 were regarded to be statistically significant.

Our study design allows the detection of differences in foot load of 20 % baseline with a power of 80 % or more. With this setting we found no statistically significant reduction of foot load up to a 20 degree extension lag of the knee joint. The opposite hindfoot load was significantly increased with 30 degrees extension lag and significantly reduced for the opposite hindfoot with 45 degrees.

As can be seen from the perspective of foot load, the intact function of adjacent joints seems to compensate an extension lag of the knee joint up to 20 degrees, but hindfoot load changes significantly with 30 degrees or more, which may be clinically relevant for patients at risk of plantar ulcerations.