Yudu - sportEX medicine - 1999-2010

DIFFICULT ANKLE 5th 1st metatarsal

Cuneiform bones

Navicular bone

Talus

Talar dome Antero- lateral aspect of talar dome

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

Cuboid bone

Lateral talar

Calcaneus process

Base of 5th metatarsal

metatarsal

Site of avulsion fractures of 5th

metatarsal

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.

Persistent

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.

The

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.

They are

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.

Grade Description

Table 1: Grading of osteochondral fractures X-ray

Isotope

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)

Anatomical detail Cost + when + Little ++ Good

detail +++

Good

shows lesion anatomical anatomical anatomical detail

detail ++++

SportEX 29 +ve +ve +ve +ve -ve +ve III Osteochondral fracture May be +ve +ve

+ve +ve

-ve -ve

Bone Scan +ve +ve

-ve +ve

Activity modification may

MRI

+ve +ve