A 26-year-old man twisted his left ankle while sliding into home
plate during a baseball game.
The ankle swelled immediately. He was able to bear weight, but
could walk only two steps without assistance.
On examination, the ankle was moderately
swollen and tender. The swelling and tenderness were greater on
the medial than the lateral side of the ankle. There was ecchymosis
over the medial malleolar area, but no deformity. Plantar and dorsiflexion
were limited due to pain. There was no tenderness over the mid-foot
(navicular or base of the fifth metatarsal).
Ankle radiographs were obtained (Figure 1).
- How would you manage this patient’s
Three radiographic views are included in a standard ankle series:
AP and lateral views and a mortise view (AP view with 15° internal
The mortise view shows the entire mortise joint space between
the talar dome and the medial malleolus, tibial plafond and lateral
malleolus (Figures 1B and 2). On the AP view, the lateral malleolus
overlaps and obscures the lateral joint space (Figure 1A).
Normal mortise view.
The entire mortise joint space should
be of uniform width, ≤4 mm (light gray).
The distal tibiofibular joint (dark gray) should be only slightly
wider than the mortise joint space, ≤5.5
The tibiofibular overlap should
be >1 mm on the mortise view.
The mortise view is key to assessing
the structural integrity of the ankle. The entire mortise joint space adjacent to the
talar dome should be of uniform width. The distal
tibiofibular joint space should be only slightly wider than
the mortise joint space. Tibiofibular overlap should be at least 1
mm on the mortise view (Figure 2). Lack of overlap implies disruption
of the distal tibiofibular joint. The distal tibiofibular joint
is also referred to as the ankle syndesmosis.
The tibia and fibula are held rigidly together by the distal
and proximal tibiofibular joints and the interosseus
ligament. Separation of the distal tibiofibular joint, even
if slight, must therefore be accompanied by a second injury, usually
a fibular fracture. If a fibular fracture is not seen on the ankle
radiographs, radiographs of the entire fibula should be obtained
because a proximal fibular fracture is likely to be present.
Clinically, all patients with ankle injuries should be examined
for tenderness along the length of the fibula, up to the knee. The “squeeze
test” (mediolateral ...