Biomechanical comparison of locked plate osteosynthesis, reamed and unreamed nailing in conventional interlocking technique, and unreamed angle stable nailing in distal tibia fractures.

INTRODUCTION: The treatment of distal tibia shaft fractures is still problematic because of the thin soft tissue envelope and less stable osteosynthesis. Therefore, nonunions are often seen in this region. When reamed nailing is performed, construct stiffness can be increased and fracture gap movement can be reduced, but in open fractures the question whether reamed nailing is before unreamed nailing is still uncertain. Therefore, unreamed nails with angle stable interlocking options were produced with the idea to improve the biomechanical properties of unreamed nails. This study compared reamed and unreamed nailing either with angle stable or conventional interlocking to plate osteosynthesis. The hypothesis was that angular stability in unreamed nailing will increase the construct stiffness and reduce the fracture gap movement. METHODS: In this study, four groups of five artificial tibiae were treated with different osteosynthesis techniques. Group 1 was treated with a reamed nailing technique, group 2 with a distally angle stable locked nail in an unreamed technique, group 3 with an unreamed nail in a conventional locking technique, and group 4 with a locked medial plate system. After osteotomy of the intersection of the distal 4/5 to 5/5 of the tibia, stiffness of the implant-bone construct and micromovement of the fragments were measured. In addition, the range of motion at the mechanical zero under torsional load was calculated. RESULTS: Biomechanical tests showed that the stiffness of the reamed nail constructs was significantly higher than the compared implants. The unreamed conventionally locked nail and unreamed distally angular stable locked nails were less stiff than the larger sized reamed nail, but the implant-bone construct showed higher stiffness values than the locked plate osteosynthesis. Regarding stiffness of the two unreamed groups, no significant differences were found. The interfragmentary movement in axial and torsional force exhibited the highest range of motion for locked plating, while the reamed nail significantly exhibited the least. The range of motion at the mechanical zero under torsional load was the lowest for the unreamed and angle stable locked nail. CONCLUSIONS: Under biomechanical considerations, the treatment of distal tibia fractures using the reamed nailing technique is before unreamed nailing, but distal angle stable interlocking of the nail may also be a satisfactory method.

Quantification of reaming debris at the fracture gap of diaphyseal A3 femur fractures after reamed intramedullary nailing and using an intramedullary application system.

BACKGROUND: After reamed nailing in long bones, there is a negligible amount of reaming debris at the fracture gap of A2 and A3 fractures. The aim of this study was to show whether there are differences between reamed nailing and reamed nailing with controlled intramedullary application of reaming debris at the fracture gap with an intramedullary application device. METHODS: In this trial, 12 human femur specimens were used. On the medullary isthmus, 12 A3 fractures were artificially produced. Afterward, reduction was done by a monocortical external fixator, and closure of the fracture gap was done with a latex finger tip. Intramedullary reaming was performed for up to 10% of the bone cortex. In six femurs, the reaming procedure alone was performed, and in six human femurs, additional controlled application of reaming debris was done. For fixation, an intramedullary plastic implant was used. The region of interest was scanned with the µ-CT 80, and the fracture gap was contoured with digital imaging software. The threshold for the reaming debris was set at 365.6 mgHA/cm³. The analysis of the bone debris located at the fracture gap was measured by percent of debris volume to gap volume. For statistical analysis, the Wilcoxon test was used and a level of significance of p < 0.05 was chosen. RESULTS: The fracture gap volume ranged from 7 mm³ to 29 mm³ without differences in both the groups. In the group without controlled intramedullary application, there was a median bone volume of 0.37 mm³ found at the fracture gap. In the group with controlled intramedullary application, a median of 2.2 mm³ of bone debris was found. The degree of filling of the fracture gap with bone debris was 2% without additional application and 13% with additional application, using the newly developed application device. CONCLUSIONS: The results show that reaming debris at the fracture gap without additional application is negligible. When using an intramedullary application device, the amount of reaming debris at the fracture gap can be increased significantly.