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[CLINICAL APPLICATION OF AXIAL LOAD MECHANICAL TESTING IN REMOVING EXTERNAL FIXATOR AFTER TIBIA AND FIBULA FRACTURES SURGERY].

OBJECTIVE
To explore the efficacy and safety of the axial load mechanical testing for removing external fixator.


METHODS
Between January 2014 and August 2015, 27 patients with tibia and fibula fractures caused by trauma underwent an external fixation. Of 27 patients, 21 were male and 6 were female with the average age of 45 years (range, 19-63 years), including 7 cases of closed fracture and 20 cases of open fracture. X-ray film results showed spiral unstable fracture in 4 cases and comminuted unstable fracture in 23 cases. All patients underwent an external fixation. Bone nonunion occurred in 3 cases because of infection, and bone nonunion combined with bone defect occurred in 1 case, who received tibial osteotomy lengthening surgery. When X-ray film showed continuity high density callus formation at fracture site, axial load mechanical test was performed. If the axial load ratio of external fixator was less than 10%, the external fixator was removed.


RESULTS
At 21-85 weeks after external fixation (mean, 44 weeks), axial load mechanical test was performed. The results showed that the axial load ratio of external fixation was less than 10% in 26 cases, and the external fixator was removed; at 6 weeks after removal of external fixator, the patients could endure full load and return to work, without re-fracture. The axial load ratio was 14% in 1 case at 85 weeks, and the X-ray film result showed that fracture did not completely heal with angular deformity; re-fracture occurred after removing external fixator, and intramedullary fixation was used.


CONCLUSIONS
External fixator axial load mechanical testing may objectively reveal and quantitatively evaluate fracture healing, so it is safe and reliable to use for guiding the external fixator removal.