Background: Recommendations for surgical treatment and expected
outcomes differ for two unstable patterns of supination-external rotation
ankle injuries. We compared the demographic characteristics and functional
outcome following surgical stabilization between the two types of
supination-external rotation type-4 fractures: distal fibular fracture with a
deltoid ligament rupture and bimalleolar fracture.
Methods: Demographic data on 456 patients in whom an unstable
fracture of the ankle was treated surgically were entered into a database and
the patients were prospectively followed. Two hundred and sixty-six of these
patients sustained either a bimalleolar fracture or a lateral malleolar
fracture with insufficiency of the deltoid ligament and widening of the medial
clear space. No medial fixation was used in the patients with a deltoid
ligament injury. All patients followed a similar postoperative protocol. The
patients were followed clinically and radiographically at three, six, and
twelve months after the surgery. Function was assessed with the Short
Musculoskeletal Function Assessment and the American Orthopaedic Foot and
Ankle Society score.
Results: Bimalleolar fractures were more commonly seen in female
patients, in those older than sixty years of age, and in patients with more
comorbidities. There was no significant association between the fracture
pattern and either diabetes or the length of the hospital stay. At a minimum
of one year postoperatively, the patients with a bimalleolar fracture had
significantly worse function, even after we controlled for all other
variables. The overall complication rate, including elective hardware removal,
was also higher in the group with a bimalleolar fracture (seventeen compared
with nine patients).
Conclusions: At one year after surgical stabilization of an unstable
ankle fracture, most patients experience little or mild pain and have few
restrictions in functional activities. However, the functional outcome for
those with a bimalleolar fracture is worse than that for those with a lateral
malleolar fracture and disruption of the deltoid ligament, possibly because of
the injury pattern and the energy expended.
Level of Evidence: Prognostic Level I. See Instructions
to Authors for a complete description of levels of evidence.