Fracture stiffness measurement in tibial shaft fractures: a non-invasive method

This paper presents a non-invasive method of assessing healing by measurement of fracture stiffness. The method works on the principle that if the load (F) applied at a certain known distance (Y) from the fracture is measured, then the moment (M = FY) at the fracture site can be calculated. By measuring the angle/deflection (θ) occurring at the fracture site using a suitable instrument (electrogoniometer), the necessary data to calculate fracture stiffness (FY/θ) would be available. The method was employed to assess the stiffness in a series of tibial shaft fractures treated conservatively, all of which healed uneventfully. This paper concentrates on a group of tibial shaft fractures in which the radiological criteria for fracture union were not satisfied even after a mean duration of 20 weeks treatment. The non-invasive method of measuring fracture stiffness supported the clinical impression of union in most cases at the first test, but was repeated on two more occasions to confirm the trend of progressive healing. The objective evaluation of fracture healing led to avoidance of surgical intervention in these patients, who went on to sound union.