Effect of intramedullary nail compression amount on the union process of tibial shaft fracture and the evaluation of this effect with a different parameter.

Objectives: This study aims to investigate the effects of different amounts of compression used in intramedullary nailing on the stress values of the fracture surface and time of the union process in tibia diaphysis fractures treated with intramedullary nails.

Patients and methods: Seventy patients (50 males, 20 females; mean age 34.0±10.7 years; range, 20 to 56 years) who had suffered from tibial shaft fractures between January 2007 and December 2015 were included in the study. Patients who had A2, A3, and B2 type fractures according to AO (Arbeitsgemeinschaft für Osteosynthesefragen) classification and those with closed fractures were included. The patients were divided into three groups. No compression was applied to Group A, dynamic compressive fixation intramedullary nailing was applied to Groups B and C. Amount of applied compression was 1 mm for Group B and 1.5 mm for Group C. Postoperative and follow-up radiographs of patients were evaluated according to Rust criteria, and functional results were evaluated according to Johner-Wrush criteria. Additionally, finite element analyses were performed separately for 1 mm and 1.5 mm compressions that were applied in Group B and C, respectively. The data were analyzed using a statistical software package.

Results: Clinical and radiological union was achieved in all patients. The average time of radiological union was 15.05±2.06 weeks in Group A, 12.48±1.42 weeks in Group B, and 11.64±1.63 weeks in Group C. The time of union for the group in which no compression was applied (Group A) was significantly longer than the other groups in which compression was applied (Group B and C) (p<0.001). Functional outcomes were 17 patients (85%) with excellent and three patients (15%) with good-moderate results in Group A, 23 (92%) excellent and two (8%) good-moderate in Group B, and 23 (92%) excellent and two patients (8%) with good-moderate results in Group C. In total, seven patients had knee pain. No infection was seen in any patient.

Conclusion: Interlocking compression intramedullary nailing is a very effective treatment method for tibial shaft fractures. As the compression applied by the nail increases, the time of union shortens significantly.