Background : Ankle fractures have a significantly worse functional outcome when they include a posterior tibial fragment. In 57 trimalleolar fractures, the effect of size, internal fixation, and anatomic reduction of the posterior fragment on the prognosis was evaluated.
Methods : A modified Weber protocol was used, providing a rating system for subjective, objective, and radiographic results. A visual analogue scale for subjective actual pain was also scored.
Results : The involvement of the articular surface ranged from 8% to 55%. Size or fixation of the fragment did not influence prognosis. Joint congruity in fragments ≥ 10% of the articular surface was a significant factor influencing prognosis. Overall, the modified Weber protocol result was excellent in 10%, good in 15%, fair in 25%, and poor in 50% of patients. However, the low average visual analogue scale of 3.0 in the whole group does not appear representative of 50% poor results, indicating that the modified Weber protocol is fairly strict and overestimates the number of poor results.
Conclusion : Joint congruity with or without fixation was a significant factor influencing prognosis. Congruity should be achieved for fragments ≥ 10% of the tibial articular surface.