Comparison of tibial alignment following bent or straight interlocking nail fixation for dogs with diaphyseal tibial fractures.

OBJECTIVE

To describe the change in tibial alignment parameters and complications between bent and straight interlocking nail (ILN) fixation of diaphyseal tibial fractures in dogs.

STUDY

DESIGN

Retrospective study.

ANIMALS: A total of 46 dogs with trauma-induced diaphyseal tibial fractures.

METHODS

Medical records of dogs with diaphyseal tibial fractures were compiled from 2014 to 2024 and categorized into bent (bILN, n = 27) and straight (sILN, n = 19) ILN groups. Tibial plateau angle (TPA), coronal angulation (CA), and medial mechanical proximal tibial angle (mMPTA) were calculated and compared with the contralateral limb. Medullary canal fill (MCF) was calculated and compared between groups. Intraoperative and postoperative complications were recorded.

RESULTS

Postoperative TPA in the affected limb was 5° higher than in the contralateral limb in the sILN group and 1° higher in the bILN group (p < .0001, p < .0377). Postoperative affected tibias in both groups were in 2° more valgus than their contralateral limb (p < .0059, p < .0301). No differences in mMPTA were noted. The MCF was 6.6% higher in the bILN group than the sILN group (p < .0163). Only one dog in the study developed a complication: moderate ILN bending and valgus. This dog was in the bILN group.

CONCLUSION

The increased TPA of the sILN group could be attributed to the tibia's natural recurvatum, which a sILN may not fully accommodate.

CLINICAL SIGNIFICANCE: While superior tibial alignment was achieved with the bILN, the detrimental effects of a higher TPA with use of a sILN need further investigation.