In this retrospective cohort study, we analysed
the incidence and functional outcome of a distal tibiofibular synostosis.
Patients with an isolated AO type 44-B or C fracture of the ankle
who underwent surgical treatment between 1995 and 2007 were invited
for clinical and radiological review. The American Orthopaedic Foot
and Ankle Society score, the American Academy of Orthopaedic Surgeons
score and a visual analogue score for pain were used to assess outcome. A total of 274 patients were available; the mean follow-up was
9.7 years (8 to 18). The extent of any calcification or synostosis
at the level of the distal interosseous membrane or syndesmosis
on the contemporary radiographs was defined as: no or minor calcifications
(group 1), severe calcification (group 2), or complete synostosis
(group 3). A total of 222 (81%) patients were in group 1, 37 (14%) in group
2 and 15 (5%) in group 3. There was no significant difference in
incidence between AO type 44-B and type 44-C fractures (p = 0.89).
Severe calcification or synostosis occurred in 21 patients (19%)
in whom a syndesmotic screw was used and in 31 (19%) in whom a syndesmotic screw
was not used.(p = 0.70). No significant differences were found between
the groups except for a greater reduction in mean dorsiflexion in
group 2 (p = 0.004). This is the largest study on distal tibiofibular synostosis,
and we found that a synostosis is a frequent complication of surgery
for a fracture of the ankle. Although it theoretically impairs the
range of movement of the ankle, it did not affect the outcome. Our findings suggest that synostosis of the distal tibiofibular
syndesmosis in general does not warrant treatment. Cite this article:
Over an eight-year period up to 1983, a total of 322 consecutive patients had operations for ankle fractures; 176 were Weber type B and 128 type C. We were able to review 230 of these patients after a mean follow-up of six years (1 to 11) including 128 with Weber B and 102 with Weber C fractures. We used an ankle score which combined symptoms and clinical and radiological findings, with a maximum score of 100 points. The mean score for all 230 was 92 (68 to 100). Fifteen of these patients had developed a distal synostosis between the tibia and fibula, three after a Weber B and 12 after a Weber C fracture. In 13 of these 15 ankles the synostosis had been visible radiologically within three months of the operation. In the other two there had been radiologically visible calcification at the three-month follow-up. In 1993, we were able to review nine of the 15 patients with synostosis using the same scoring system. At a mean follow-up of 14 years (12 to 18) the mean score for those with synostosis was 91 (71 to 100), much the same as this group’s previous score and the mean score of the whole group of operated patients. We conclude that distal tibiofibular synostosis after ankle fracture usually causes few symptoms and does not generally require any treatment.
