[Comparative study of monolateral and circular fixator in the treatment of infectious tibial nonunion]

To compare treatment effect of monolateral and circular external fixator in infectious tibial nonunion and to explore external fixation structure with better osteogenic ability and fewer complications.

A retrospective analysis was performed on 150 patients with infectious tibial nonunion admitted from January 2010 to December 2014. Patients who met the inclusion and exclusion criteria were divided into monolateral fixator group and circular fixator group according to the type of external fixation. Demographic and perioperative data of the two groups were collected. New bone quality was assessed by pixels ratio, treatment effect was assessed by complications. Notes for treatment was explored by case analysis.

A total of 64 patients with infectious mid-tibial nonunion were included, 26 in monolateral fixator group and 38 in circular fixator group. There was no difference in demographic data between two groups. The pixel ratio of new bone between two groups was from 0.91 to 0.97 with an average of (0.94±0.03), and from 0.93 to 0.97 with an average of(0.95±0.02), respectively, with no statistical significance (P>0.05). The external fixation index was from 34.1 to 50.6 with an average of (42.3±8.3) days /cm in monolateral fixator group and from 44.5 to 56.1 with an average of (45.8±10.3) days/cm in the circular fixator group, and the difference was not statistically significant (P>0.05). There were 7 cases (26.9%) of complications in monolateral fixator group and 5 cases (13.2%) in circular fixator group, the difference was not statistically significant (P>0.05), but 5 cases of foot ptosis in monolateral fixator group and none in circular fixator group. The time of weight bearing in monolateral fixator group was later than that in circular fixator group, and the difference was statistically significant (P<0.05).

Monolateral and circular fixators can achieve equivalent bone formation in the treatment of infected tibial nonunion. Circular fixator is recommended for patients with severe osteoporosis or concomitant medical diseases requiring early weight bearing. Hydroxyapatite coated screws are recommended if a monolateral external fixator is selected when the expected enlarged length is long and the fixation time is long and close monitoring of the ankle movement is required to avoid foot droop.