It is widely accepted that the use of radiographs to assess fracture healing is, at best, misleading. It is also known that physical manipulation of the fracture can also produce misleading results. The determination of a fracture healing using a quantifiable rather than a qualitative assessment process is desirable for two reasons. Clinically, it avoids the premature or delayed removal of the treatment regime. In research it is required to better distinguish between treatment methodologies in comparative studies. The aim of this paper is to present the need for such a measurement and describe alternative methods that have been adopted. Further, a new device is presented that enables users to measure the linear and non-linear properties of healing callus with a high degree of certainty. An initial trial of 21 patients with unstable diaphyseal tibial fractures was conducted. The patients had their fractures reduced using the Staffordshire Orthopaedic Reduction Machine and subsequently treated with an external fixator. From six weeks post treatment the progress of healing was assessed using manipulation, radiographs, fracture stiffness and multi-planar material property assessment. Fracture healing was deemed to have been obtained when a fracture stiffness in two planes was greater than 15 Nm/degree. The paper presents results that demonstrate that the assessment of fracture healing using traditional manipulation and radiographs is erroneous. It will also demonstrate that the measurement of fracture stiffness can also be erroneous if loading rate is ignored. It further shows that fracture stiffness must be measured in two planes. Initial results examining principal stiffnesses will also be shown, along with the measurement of material properties based on work rather that stiffness.
A study was undertaken of externally fixed tibial fractures in which a fracture stiffness of greater than 15Nm/° was used to define when the frame was removed were included 37 patients were studied; 20 (54%) non-smokers and 17 (46%) smokers. The two groups were comparable (ANOVA p=0. 35) for other factors. Mean healing times in the non-smokers was 15. 5 weeks and in smokers was 21. 2 weeks (t-test p=0. 05). We encourage all patients with tibial fractures to stop smoking by quoting an increase of treatment time of six weeks.
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.
We have studied the progression of healing in 103 unstable fractures of the tibia. In 76 patients we removed the external fixator once the stiffness had reached 15 Nm/° in the sagittal plane. Deformity at the site of the fracture subsequently occurred in four patients. In a further 27, we measured stiffness in several planes and removed the fixator only when the stiffness reached 15 Nm/° in each. We found that stiffness in two orthogonal planes may differ widely (maximum difference 9.0 Nm/°, mean 4.1 Nm/°). There were no failures in the second group. We advocate that fracture stiffness be measured in two orthogonal planes when assessing tibial healing and suggest that values above 15 Nm/° in two planes give an indication that it is safe to remove the fixator.
