Non-unions after fixation of diaphyseal humeral fractures using Hackethal´s elastic bundle nailing technique

Background Numerous treatment modalities exist for the treatment of diaphyseal humeral fractures. The aim of this study was to identify factors that contribute to the development of non-union after internal fixation of diaphyseal humeral fractures using Hackethal´s intramedullary elastic bundle nailing technique. Materials and methods In the time period from 2001 to 2010 156 patients with diaphyseal humeral fractures were treated surgically using Hackethal´s technique. In six of them (3.8%) a non-union developed. This group comprised of three women and two men aged 63-69 years and one woman aged 37 (mean age 62 years). The following parameters were recorded: patient age, sex, comorbidities, substance abuse, mechanism of injury, fracture type and location according to the AO/ASIF classification, the individual indication to surgery and the operative technique. Results The mean age of entire group was 51.3 years, the non-union group had a mean age of 62 years (p=0.132). Five of six non-unions (83%) were observed in patients in their sixties, which made only 15.4% of entire group. In the subgroup of sexagenarians, non-union developed in 20.8% of surgically treated patients, compared to 3.8 % in entire group. In the union group, the fracture had been caused by high energy trauma like fall from a height and motor vehicle accident in 52% of patients. In patients who developed non-union the fracture had been caused by high energy trauma in 67%. Among the 22% of patients who were drunk at the time of injury, none developed non-union. The fracture location at the humeral diaphysis did not differ between the entire group and the non-union group. Non-union developed more frequently in patients with more complex fractures (AO/ASIF type B). In the non-union group, two patients (33%) underwent surgery for comminuted fractures (C3 type). In the 150 patients with complete bony union, AO type C fractures were treated with the bundle nailing technique in three young patients (2%). Non-union developed in 2.6% of patients with adequate indication (AO type A and B fractures) and in 40% of patients with inadequate extension of the indication to AO type C fractures (p=0.012). In five of six cases (83%) with non-union the medullar cavity was filled incompletely with the implants, in one case (17%) additionally a significant distraction of the main fragments persisted after surgery. In the group of primarily healed patients these technical errors occurred in nine cases (6%). With correct surgical technique the development of a non-union was observed in 0.7% of patients, with incorrect technique in 35.7% (p<0.001). Thus, both inadequate indication and inadequate technique were associated with a significantly increased risk of non-union. Conclusion Treatment of diaphyseal humeral fractures with Hackethal’s intramedullary elastic bundle nailing resulted in a high overall union rate. Factors contributing to the development of non-union were patient age over 60 years, multifragmentary fractures, extension of this method to AO type C fractures and technical errors. Key words non-union, fracture, humeral diaphysis, elastic bundle nailing, Hackethal