Figure 2a+b: Superior view of the main bones of the foot a)separated by computer
The more common differential diagnoses will now be discussed in turn.
Differential diagnosis 1. POST TRAUMATIC SYNOVITIS History: As previously discussed the anterior talo-fibular ligament is thin and closely intimated with the capsule of the ankle.
Tearing of the ATFL is likely to
result in capsular tearing also producing a haemarthrosis. If weight-bearing activity is resumed too soon, then persistant ankle pain and swelling may occur as a result of synovitis.
Treatment: Local treatment and non- steroidal anti-inflammatories may help to resolve this but in more chronic cases injection with cortico-steroid usually pro- duces excellent and early resolution of symptoms.
Injection should be followed
by limited weight-bearing activity for 48 hours.
On the isotope bone scan there
may be an increase in the soft tissue uptake.
MRI will highlight the effusion
within the joint that may be clinically detectable as a ‘boggy’ anterior swelling or as a fullness when viewed posteriorly.
2. OSTEOCHONDRAL FRACTURES OF THE TALAR DOME History: Some studies have suggested that up to 80% of ankle inversion injuries will develop some form of chondral lesion on the talar dome (Fig.2) and about 5% will have actual osteochondral fracture. These are important injuries not to miss that can have significant morbidity in the long-term.
b)in their correct anatomical position
Base of 5th metatarsal
Site of avulsion fractures of 5th
draw or through a certain arc of move- ment as the chondral defect is impacted against the tibia or fibula. swelling is likely to be present.
Investigation: The isotope bone scan will highlight an area of increased uptake within the talus but it is important then to grade the injury by CT or MRI as this will determine the management.
gradings are shown in the table below. MRI is currently the investigation of choice when a talar dome fracture is sus- pected as this will both confirm and grade the lesion.
Cause: Osteochondral fractures occur par- ticularly when there is a compressive component to the injury, eg. on landing. The fractures tend to involve the antero- lateral or postero-medial components of the talar dome (Fig.2a) as the talus rotates within the ankle mortise.
Presentation: Persistent pain with a con- stant feeling of aching is a characteristic feature. There may be pain with anterior
Management: Grade I and II lesions have been treated traditionally by non-weight bearing casts for 6-8 weeks. However I have successfully managed these lesions using an Aircast boot, non-weight bearing which does allow removal for hygiene, range of motion maintenance and access for other treatment modalities.
also re-usable and provide a cost-effective treatment. A slow and graded return to weight-bearing activity is required follow- ing removal from the brace. Grade IIa, III and IV fractures tend to require surgical intervention and are best managed by arthroscopic removal of a separated frag- ment or cyst.
Table 1: Grading of osteochondral fractures X-ray
I Subchondral fracture II Osteochondral
fracture- no separation IIa Subchondral cyst
with separated but not displaced fragment
IV Osteochondral fracture
with separated and displaced fragment(s)
Sensitivity Misses most +++ ++ (misses +++ Grade I)