Comparison of ultrasonography and radiography in assessment of the heel pad compressibility index of patients with plantar heel pain syndrome. Measurement of the fat pad in plantar heel pain syndrome.

Aims: The shock absorption of the heel fat pad is assessed by heel-pad compressibility index measuring the thickness of the heel pad on the lateral radiographs unloaded and loaded by body-weight. Ultrasonography is an easily applicable method without radiation and magnification inherent in radiographs. There are no reports comparing these measurements by diagnostic ultrasonography and direct radiography in healthy individuals and in different clinical entities. The efficacy of ultrasonography in assessment of heel-pad compressibility index in patients with plantar heel pain syndrome was investigated comparing it with direct radiography.

Methods: The loaded and unloaded heel-pad thicknesses by ultrasonography and direct radiography were measured in 69 feet of 42 patients with plantar heel pain syndrome and their results were compared.

Results: In direct radiographs, the mean unloaded heel-pad thickness was 20+/-2 mm and ranged from 14 to 26 mm. Heel-pad compressibility index was 0.62+/-0.09. There was a strong positive correlation between the measurements of the unloaded thickness (r=0.84, P<0.001) and also between the measurements of the loaded thickness (r=0.88, P<0.001) done using ultrasonography and direct radiography. The difference between the results of measurements in two modalities did not exceed +/-1 mm in 50% and +/-2 mm in 81% in unloaded position and +/-1 mm in 62% and +/-2 mm in 82% in loaded position.

Conclusion: Measuring unloaded and loaded heel pad thickness by ultrasonography is reliable in the adult feet with heel pain. The preference of ultrasonography is reasonable in the studies involving the heel fat pad.