Background: Deltoid incompetence in association with an isolated
fibular fracture is assumed to be present if there is medial tenderness,
ecchymosis, or substantial swelling. We sought to determine whether these
soft-tissue indicators predict deltoid incompetence by comparing such findings
with the findings on stress radiographs.
Methods: Over a thirty-two-month period, 138 patients who presented
acutely with a Weber type-B supination-external rotation (SE) fibular fracture
were evaluated for tenderness (in nine locations), ecchymosis, and swelling.
Patients who presented with an apparently isolated fibular fracture and an
intact ankle mortise (with a medial clear space of =4 mm and no talar
subluxation) were evaluated with a stress radiograph to determine deltoid
competence. Four groups of patients were identified: those who had an SE2
fracture (defined as those who had a stable ankle on the stress radiograph),
those who had a stress (+) SE4 fracture (defined as those who had an unstable
ankle on the stress radiograph), those who had an SE4 fracture (defined as
those who presented with a wide medial clear space), and those who had a
bimalleolar fracture. These four groups were compared with regard to
tenderness, swelling, and ecchymosis at the time of initial presentation.
Patients with SE2 injuries were allowed immediate weight-bearing.
Results: Of the ninety-seven patients who presented with an isolated
fibular fracture and an intact mortise, sixty-one had a stable SE2 injury and
thirty-six had an unstable stress (+) SE4 injury. All stable SE2 injuries
healed with an intact mortise. Medial tenderness, ecchymosis, and swelling
were not predictive of deltoid incompetence (instability).
Conclusions: Stress radiographs allow for the accurate diagnosis of
deltoid incompetence in patients with Weber type-B SE fibular fractures and no
other osseous injury. Soft-tissue indicators are not accurate predictors of
instability. If medial tenderness, ecchymosis, and swelling are used as
operative indications, in some cases surgery may be performed on stable
Level of Evidence: Diagnostic study, Level II-1
(development of diagnostic criteria on basis of consecutive patients [with
universally applied reference "gold" standard]). See Instructions
to Authors for a complete description of levels of evidence.