Investigations
1st investigations to order
x-rays
Test
Should be ordered initially if the clinical suspicion for fracture is very high, to rule out bony injuries.
Can be repeated in 2 weeks if symptoms do not improve with initial treatment (e.g., in wrist injury to rule out scaphoid fracture).
Result
negative
MRI
Test
Can differentiate between complete and incomplete tear with reasonable certainty. It is considered gold standard in identifying acute ligamentous injuries of the ankle.[33]
Result
grade 1 muscle strain: focal hyperintensity in T2 sequence; grade 2 muscle strain: hyperintensity in T2 in acute phase with muscle fibre retraction; grade 3 muscle strain: hyperintensity in T2 with bell clappers sign due to muscle fibres floating in the haematoma; grade 1 ligament sprain: focal hyperintensity in T2 sequence; grade 2 ligament sprain: hyperintensity in T2 in acute phase; grade 3 ligament sprain: hyperintensity in T2 with loss of integrity of the ligament
ultrasound for non-ligament injuries
Test
Initial investigation in groin area or if close to musculotendinous junction.
In situations of non-availability of MRI, ultrasound can be helpful.
Confirms muscle sprain and grades it.
The diagnostic reliability of ultrasound is observer-dependent and requires a skilled practitioner.[34]
Ultrasound is not useful for ligament sprains.
Result
grade 1: generalised or focal hyperechogenicity; grade 2: interruption of fibres in the echogenic perimysial striae; grade 3: muscle stump appears rounded and hyperechogenic
Investigations to consider
diagnostic arthroscopy
Test
More useful in ankle and wrist injuries. Used to differentiate between incomplete and complete ligament sprain.
Result
torn ligament invaginated into the joint
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