Sports Medicine: Just the Facts

• Anteroposterior, lateral, and oblique radiographs
  should be obtained if any of the below criteria are
  present:
  
  
  1. Lateral or medial malleolar bone tenderness is
     present
  
  
  2. Patient unable to bear weight for four steps both
     immediately post injury and in the emergency
     department.
  
  
  
  


• The Ottawa ankle rules do notapply in the following
  settings:
  
  
  1. Age less than 18 years
  
  
  2. Multiple painful injuries
  
  
  3. Pregnancy
  
  
  4. Diminished sensation caused by neurologic deficit
  
  
  
  


• These criteria have been found to be 100% sensitive
  for detecting fracture while decreasing the incidence
  of unneeded radiographs (Stiell et al, 1993).

RADIOGRAPHS

• If radiographs are warranted, they should be examined
  closely for the following fractures that mimic ankle
  sprains:
  
  
  1. Medial or lateral malleolus
  
  
  2. Talar dome
  
  
  3. Posterior malleolus (posterior distal tibia)
  
  
  4. Posterior talar process
  
  
  5. Lateral talar process
  
  
  6. Anterior calcaneal process
     7.Flake fracture off the posterior distal fibular rim,
     indicating a tear of the superior peroneal retinacu-
     lum and peroneal tendon dislocation
  
  
  7. Navicular fracture
  
  
  
  


• Radiographs should also be examined for radi-
  ographic evidence of syndesmotic injury:
  1.Widening of the medial clear space of more than
  5 mmbetween the medial talar facet and medial
  malleolus, produced by lateral talar subluxation, is
  indicative of a tear of the deltoid ligament and
  probable syndesmotic ligament instability.
  2. Widening of the tibiofibular clear space of greater
  than 5 mm or a tibiofibular overlap of less than
  10 mmmay also indicate syndesmotic injury.

STRESS RADIOGRAPHS

• Not required to make a diagnosis of an acute ankle
  sprain.


• Used primarily to document mechanical instability as
  a cause of chronic lateral ankle instability symptoms.


• Can be performed with or without the injection of
  local anesthetic into the lateral ankle. An injection of

5 cc. of 1% xylocaine into the anterolateral ankle may

yield a more reliable test as a result of patient comfort.

•Talar tilt test

1. The talar tilt test is performed by taking an antero-
   posterior(AP) or mortise view of the ankle while
   performing an inversion stress on the slightly plan-
   tar-flexed ankle.


2. The talar tilt angle is obtained by measuring the
   angle subtended by a line parallel to the distal
   tibial articular surface and a line drawn along the
   superior articular surface of the talus.


3. Most authors agree that a difference of 5°–15°in
   talar tilt between the injured and uninjured side is
   diagnostic of mechanical ankle instability (Safran
   et al, 1999b).
   •Anterior drawer test


4. Anterior drawer stress radiographs are performed
   by taking a lateral radiograph of the ankle while
   attempting to translate the talus anteriorly within
   the mortise, as in the clinical anterior drawer test.


5. The anterior drawer is measured as the shortest dis-
   tance between a point on the posterior aspect of the
   distal tibial articular surface and a point on the pos-
   terior aspect of the talar dome.


6. An anterior drawer difference of greater than 3mm
   between injured and uninjured ankles is thought to
   be diagnostic of ATFL laxity (Anderson and Lecocq,
   1954).

• Stress radiographs for syndesmotic instability

1. A mortise stress radiograph of the ankle syn-
   desmosis can be obtained by placing an external
   rotation force on the ankle while stabilizing the
   proximal tibia with the knee flexed 90°.


2. Abnormal widening of the mortise and lateral talar
   shift indicates distal syndesmotic instability.

MRI

• Magnetic resonance imaging (MRI) not is needed for
  diagnosis in the acute setting unless occult fractures
  or tendon injury is suspected.


• MRI is most useful in diagnosing causes of the chron-
  ically sprained ankle and MRI can diagnose talar
  dome injuries, peroneal tendon tears, bone bruises, or
  other occult fractures.

CT SCAN

• No needed in the acute setting unless an occult frac-
  ture is suspected.


• More valuable than MRI in delineating bone or joint
  pathology, e.g., talar dome fractures, lateral talar
  process fractures, tarsal coalition, subtalar arthritis,
  and loose bodies.

368 SECTION 4 • MUSCULOSKELETAL PROBLEMS IN THE ATHLETE