[Dynamic pedobarography in postoperative evaluation of pes cavovarus]

Pes cavovarus is a complex deformity of the forefoot, the midfoot and the hindfoot, frequently of neuropathologic etiology. The goals of surgical interventions consist of anatomical and functional correction of the foot deformity by soft tissue and bony procedures. Preoperative planning and postoperative assessment are based on clinical and radiographic examination. The present study was undertaken to find out if pedobarographic outcomes correlate with those postoperative results and if the dynamic pedobarography provides useful information in the functional evaluation of cavovarus feet.

Sixteen patients with cavovarus foot deformity (mean age 32.8 years, range 17-56) with a total of 21 feet were examined before and after surgery. The average follow-up time was 24 months (range 6-50). The study protocol included physical examination, angle measurements on weightbearing radiographs and dynamic pedobarography. The patients performed five trials at self-selected speed for each foot. The amount of correlation was established between: plantar peak pressure pattern and patient's subjective functional result, the evidence of callosities and increased peak pressures in forefoot and midfoot regions of interest, the change of calcaneal pitch or Hibbs' angle (first metatarsal - calcaneal axis) and the midfoot contact area.

The patient's functional opinion and pedobarographic improvement of peak pressures correlated in 7 feet, the patients estimated the result better in 13 feet and worse in 1 foot. In 4 regions of interest callosities and increased peak pressures occurred together in 69% of the cases, in 15.5% callosities were observed without augmented peak pressures and in 15.5% increased peak pressures were measured without evidence of callosities. No correlation was found between radiographic and pedobarographic parameters which describe a reduction of the cavus deformity: calcaneal pitch angle and midfoot contact area (Pearson correlation coefficient r=- 0.36), Hibbs' angle and midfoot contact area (r=0.55), although all parameters changed significantly (p=0.001).

Pre- and postoperative assessment of the cavovarus foot is mainly based on static methods such as clinical and radiographic evaluation. The results of this study demonstrate that the dynamic measurement of plantar peak pressures and contact area offers limited information about functional and anatomical improvement after surgery. Patients with severe deformities and muscular discoordination have difficulties walking consistently on the platform at each trial and severe decrease of plantar contact area makes the exact positioning of the masks difficult, which leads to problems with standardised measurements. In this context, the dynamic pedobarography cannot be used as a profitable diagnostic tool which provides an objective measurement that can add a dynamic component to a clinical or radiographic examination.