An analysis of effective factors of nonunion after distal radius metaphyseal fracture with cross Kirschner wire fixation

SHI Li-wei; ZHANG Li-jun; ZHAO Qun; LI Qi-wei; WANG En-bo; LI Lian-yong

doi:10.3969/j.issn.2095-252X.2017.07.006

Abstract：Objective To retrospectively study the clinical data of the children with nonunion after distal radius metaphyseal fractures with cross Kirschner wire fixation, and to find the causes and effective factors in the treatment of nonunion. To compare the fixation methods for both radius nonunion and fresh distal radius metaphyseal fracture, and then to suggest a reliable fixation method for distal radius metaphyseal fracture. Methods The clinical data of both the children with radius nonunion and those with distal radius metaphyseal fractures were retrospectively analyzed. From June 2012 to June 2014, there were 49 children with fresh distal radius metaphyseal fractures. There were 40 males and 9 females, whose average age was 8.9 years at the time of treatment. Among them, 46 children were treated by close reduction with Kirschner wire fixation, and 3 children by open reduction with Kirschner wire fixation. Eleven patients were treated by double Kirschner wires intramedullary fixation through ( group A ), 11 patients by single Kirschner wire intramedullary fixation through ( group B ), 23 patients by double Kirschner wires fixation with one through and one cross ( group C ), and 4 patients by double Kirschner wires fixation cross ( group D ). All the 49 patients were followed up for an average of 8.6 months ( range: 6 - 48 months ). According to Hertel's criteria, bone union had been realized in 48 cases, with 1 case of nonunion. This case and another 2 cases, who were firstly treated outside the hospital with nonunion confirmed in our hospital, were taken as the radius nonunion group ( group E ). There were 3 patients with nonunion. Open reduction with Kirschner wire fixation were firstly performed. Six months after the operation, there was no bony callus. The diagnosis of radius nonunion was confirmed. In the second operation, all the patients were treated by open reduction with plate immobilization and autogenous bone graft in the nonunion. The plaster cast was used after the operation. After removal of the plaster cast, limb weight-bearing exercise gradually began. The patients had the regular follow-up of 2 years, the same as that for the patients with nonunion. The clinical data, imaging diagnosis, treatment methods and outcomes of all the patients were analyzed. All the data were processed by statistical software SPSS19.0, and χ2 test and t-test were used to compare the differences among groups. Results The 3 nonunion children were followed up. Radius nonunion occurred again in 1 patient at 7 months after the first surgery. The parathyroid hormone was increased before the second surgery. The therapy of the second surgery was open reduction with intramedullary fixation, and autogenous bone graft in the nonunion, at the same time the hyperparathyroidism was given in the Department of Endocrinology. The final nonunion was cured at 6 months after the second operation. In the remaining 2 patients with no diseases related to bone growth or metabolism, the final nonunion was cured at 2.5 months after the first surgery. The other 49 children with fresh distal radius metaphyseal fractures were followed up. The mean follow-up was 8.6 months. A total of 48 patients were cured, and nonunion occurred in 1 patient. The patient was in the group of 4 patients treated by double Kirschner wires fixation cross. No patients had nonunion in the other 3 groups. The overall effective rate was 97.9%. The data of intramedullary fixation group and non-intramedullary fixation group were compared by χ2 test, and there were statistically significant differences. It was presented that intramedullary fixation was superior to non-intramedullary fixation. Based on the comparison of X-ray in the patients with nonunion and those without nonunion, the ratio of the distance from the distal fixation point to the fracture line to the distance from the distal fixation point to the wrist was calculated. The ratio of nonunion group was obviously lower than that of the union group according to the analysis by t test, and there were statistically significant differences. Conclusions The therapy with cross Kirschner wire fixation after the open reduction for distal radius metaphyseal fracture should be carefully used. If cross Kirschner wire fixation will be used, the distal fixation point should be as far as possible from the fracture line. The ratio of the distance from the distal fixation point to the fracture line to the distance from the distal fixation point to the wrist should be 0.5 at least. If the patients with fractures are treated by open reduction, rigid plate fixation is the best choice in the case of well local conditions. If there are bad local conditions or the patients are treated by close reduction, at least one Kirschner wire intramedullary fixation through the radius is necessary. We have to pay attention to the diseases related to bone growth and metabolism before operation for the nonunion patients, in order to avoid the occurrence of nonunion after the treatment.