Native tibia valga: a potential source of varus malreduction during intramedullary tibial nail fixation of tibial shaft fractures.

PURPOSE

To determine the effect of native tibia valga on intramedullary nail (IMN) fixation of tibial shaft fractures.

METHODS

Retrospective comparative cohort analysis of 110 consecutive patients with tibial shaft fractures undergoing IMN fixation at an urban level one trauma centre was performed. Medical records and radiographs were reviewed for demographics, tibia centre of rotation of angulation (CORA), nail starting point, incidence of varus malreduction, and nail/canal proportional fit.

RESULTS

Tibia valga (CORA of ≥ 3 degrees) was present in 37 (33.6%) patients. The anatomic nail starting point distance (in relation to the lateral tibial spine) was significantly greater in the tibia valga group (12.0 mm vs. 5.0 mm, mean difference: 7.1 mm, 95% CI: 5.8 to 8.3 mm, p < 0.0001). Varus malreduction was more common in the tibia valga group (10.8% vs. 1.4%, proportional difference: 9.4%, 95% CI: - 1.0 to 21.3%, p = 0.04). Varus malreduction in the tibia valga group was associated with a decreased nail width/inner canal width proportion on multivariate analysis (OR = 0.683, 95% CI: 0.468 to 0.995, p = 0.0004).

CONCLUSION

Native tibia valga is common, and the use of a standard coronal IMN starting point with poor nail fit can lead to iatrogenic varus malreduction. In patients with tibia valga, maximizing nail fit or utilization of a medial starting point should be considered.