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.