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Lower limbs trauma 2010 \ fifth lecture

Talus fractures

These are rare fractures in adults and children. They are usually a result of forced dorsiflexion of the foot with impingement of the neck of the talus on the distal tibia resulting in fracture of the talar neck. Road traffic accidents are now the most frequent cause, but falls from a height are also a well recognized cause.

Clinically, there is a lot of hindfoot and ankle swelling but no deformity unless there is considerable displacement or talar dislocation. Diagnosis is established by plain radiographs, but a CT scan may give useful additional information regarding the degree of displacement and comminution. The main risk with talar neck fractures is the potential loss of blood supply to the body of the talus (avascular necrosis). The risk of this in severely displaced fractures may be as high as 90%.

Treatment :

Undisplaced fractures may be treated non-operatively in a cast for 6 weeks. Displaced fractures should be treated by open reduction and fixation, as this has been associated with lower risks of avascular necrosis (AVN) than non-operative management. Patients are immobilized in a cast after surgery for 6 weeks. AVN can develop at any time within 2 years of injury and patients should be followed for this period with regular radiographs.

CALCANEUS FRACTURES

Fractures of the calcaneus typically occur as the result of a fall from a height and are common in building site workers, particularly roofers. Bilateral fractures are present in 10% of cases. Other injuries do occur and there is an association with fractures in the lumbar spine. These are unusual injuries in children.

Clinical assessment reveals swollen heels, with loss of heel height, marked swelling and bruising, and skin blistering in severe cases.

 Diagnosis is confirmed by plain radiographs. In 75% of cases the subtalar joint is involved. CT scanning is necessary in these cases to determine the degree of joint involvement and displacement and to make a decision regarding treatment.

Treatment:

Extra-articular fractures can be treated non-operatively in most cases unless there is a large displaced fragment with the insertion of the Achilles tendon. Non-operative treatment entails cast immobilization for 4-6 weeks. Less severe crack fractures with no displacement can be treated partially weight-bearing without the use of a cast.

The treatment of displaced fractures remains controversial.

 The outcome of displaced fractures of the calcaneus with subtalar involvement has often been reported as very poor, irrespective of the mode of treatment.

However, in the past two decades, modern methods of internal fixation have been associated with much better outcomes, although disappointing functional results with heel stiffness, pain and subtalar arthritis are still common.

 Poor prognostic features are: age over 40 years, severe comminution, smoking and diabetes. Patients who develop painful subtalar arthritis after injury are treated with subtalar arthrodesis

MID-FOOT INJURIES

Injuries of the tarsal bones are very uncommon in adults and children. Minor undisplaced injuries can be treated non-operatively in a cast for 4 weeks. More severe injuries are usually the result of high-energy trauma, often with a crushing component . These may be difficult to treat, but some form of internal fixation and, occasionally, external fixation may be necessary. With more extensive joint damage the outcome is poor with pain and stiffness. Late fusion may be needed.

Mid-foot dislocations through the tarso-metatarsal joint are referred to as a Lisfrance dislocation. The metatarsals typically displace laterally in relation the midfoot. This injury is best treated by internal fixation with a combination of screws and wires, which are placed across the dislocated joints after open reduction. They are removed once healing is complete. Non-operative treatment leads to poor results with valgus deformity of the forefoot and a flattened medial plantar arch.

METATARSAL AND PHALANGEAL INJURIES

The majority of these fractures occur as a result of low-energy trauma and they can usually be treated non-operatively in adults and children. For isolated metatarsals a padded dressing may be all that is required. Multiple injuries or those associated with a lot of pain may require a short period of cast immobilization. Most phalangeal fractures of the toes are treated with analgesia only. There are a few exceptions that merit consideration of operative treatment.

Displaced fractures of the first metatarsal are very uncommon because the bone is very strong and only fractures as a result of significant force. Because of the importance of this bone in maintaining the medial arch and in weight-bearing in the foot, displaced fractures are best treated operatively with plating. Multiple metatarsal neck fractures are occasionally seen in high-energy injuries. They often result in plantar displacement of the meta-tarsal heads. Healing in this position can result in troublesome metatarsalgia later. Open reduction and wire fixation is recommended.

Finally, fractures of the proximal third of the 5th metatarsal (Jones fracture) have a propensity to non-union. They can be treated non-operatively, but careful follow-up is

required to detect non-union, which may require internal fixation.

Compartment syndrome of the foot may result from a crushing injury with little bony damage, as the foot has musculo-fascial compartments. The diagnosis should be considered in any patient who has sustained a high-energy fracture or crush injury. Fasciotomy and decompression through dorsal and medial incisions is the treatment of choice to avoid an ischaemic contracture developing