Importance of axial penile rigidity in objective evaluation of erection quality in patients with erectile dysfunction - Comparison with radial rigidity

Introduction: The aim of this prospective study was to evaluate the usefulness of measurement of axial penile rigidity, compared with radial penile rigidity. Patients and Methods: Twenty-two patients, aged 21-75 years old (a mean of 50), with erectile dysfunction underwent axial penile rigidity measurements by the digital inflection rigidometer (DIR) as well as radial penile rigidity measurements by the RigiScan Plus during intracavernous pharmacological erection testing. Results: A significant correlation was recognized between axial rigidity, and radial rigidity at the tip (p = 0.0024) and base (p = 0.0098) of the penis. In 10 patients, the DIR revealed axial rigidity of 550 g or more, and they also had radial rigidity of 60% or more at the tip and base. In 14 and 17 subjects, radial rigidity of 60% or more was observed at the tip and base, respectively. Four of the former 14 and 7 of the latter 17 had axial rigidity <550 g. Conclusions: A RigiScan results of radial rigidity of 60% or more should be interpreted cautiously and not necessarily regarded as normal.