Fracture bending stiffness of 15 Nm/° measured in the sagittal plane provides an objective end-point for healing in tibial fractures treated with external fixation ( A series of omniplanar fracture stiffness measurements were undertaken on patients with tibial fractures treated by external fixation. The first measurements were performed when the fracture was deemed sufficiently stiff to allow the fixator to be removed safely. These were continued at regular intervals until union, defined as a uniplanar stiffness of greater than 15Nm/° in at least two planes. Polar stiffness plots were obtained and analysed. The stiffness envelope varied significantly in all planes but the general shape of the polar plot remained the same with successive tests, with an overall increase in stiffness. The polar stiffness measurements were significantly different than concurrent uniplanar measurements; this reflects the difficulty in defining the plane of bending accurately in uniplanar measurements. The fracture configuration and healing fibula had unpredictable effects on the polar stiffness. The measurement of polar fracture stiffness polar gives new insight into how the mechanical environment of a fracture changes during healing. Fracture stiffness is not uniform and this may have implications on when it is safe to remove the fixator.
Fractures of the tibia should be reduced as accurately as possible. Fractures opened for internal fixation can be reduced accurately under direct vision, but unstable closed fractures treated by external fixation must be reduced by indirect means. Most surgeons reduce the fracture by manipulation, insert the bone-screws, apply the fixator and then manipulate the fracture again to improve the reduction before locking the fixator. Using this technique it is difficult to obtain a perfect reduction. A poor reduction can prolong healing time and may lead to malunion causing long-term impairment of function. A good reduction lessens the loading imposed on the bone-screws and fixator. We describe a device with which closed tibial fractures can be reduced with a predictable high degree of precision prior to external fixation. A reduction device, the Staffordshire Orthopaedic Reduction Machine (STORM), was developed. Externally fixed unstable closed tibial fractures reduced by conventional methods (n=37) were compared with those reduced using the STORM (n=41). In the STORM group, the holes for the fixator pins were only drilled once the fracture had been perfectly reduced and no further manipulation was undertaken after the fixator had been applied. Reductions were assessed by measurements of radiographs taken at, and 4 weeks after, fixator removal. All cases were treated with monolateral external fixation. The STORM significantly improves the precision of reduction of unstable tibial fractures without increasing operating time. Its use obviates the need for reduction joints on external fixators for the tibia.
