Aviator's astragalus
Definition
Isolated fracture of the neck of the talus (astragalus) 1
Mechanism of injury
Forced dorsiflexion of the ankle joint with high-energy axial load, resulting in impaction of the talar neck against the anterior tibia 1
Historical context
In 1919, H. Graeme Anderson, a British surgeon who had consulted for the Royal Flying Corps during the Great War, published a case series of talar injuries sustained by downed fighter pilots 2.
When bracing for impact, the sole of the pilot’s foot is pressed against the rudder bar, where the talus absorbs the force of the axial load and becomes the centre of fracture 3. Anderson coined the term ‘aviator’s astragalus’ to describe the injury. Interestingly, ‘astragalus’ referred to the Greek term for dice, as the tarsal ‘knucklebones’ of hooved animals were used as primitive dice in gambling and fortune-telling in ancient times 4.
Modern context
As non-lethal aircraft crashes became more infrequent due to technological advances in aviation, as well as the widespread adoption of parachutes, the occurrence of this specific injury has become less commonplace amongst pilots.
Today, the most frequent cause of talar neck fractures are seen in high-speed head-on motor vehicle collisions, which can reproduce similar forces through a foot pressed against the brake pedal 5.
Chauffeur fracture
Definition
Oblique fracture through the base of the radial styloid process, with intra-articular extension into the radiocarpal joint 6
Mechanism of injury
Sudden hyperextension and abduction injury of the wrist, with impaction of the radial styloid process by the scaphoid bone 7
Historical context
In 1904, Just-Marie-Marcellin Lucas-Championnière, a French orthopaedic surgeon, observed an emerging type of radial fracture amongst cab-drivers and chauffeurs 8.
The motors of early automobiles of that era were started by vigorously turning a long handle attached to the crankshaft of the engine in a clockwise manner. Premature ignition of the engine can cause it to ‘backfire’, resulting in the crank-handle spinning with force in the opposite direction 9.
If the operator is still gripping the handle, a backfire is likely to jar the wrist backwards, and may subsequently cause an avulsion fracture of the radial styloid process 10.
Modern context
The invention of the electric starter motor, a less dangerous and laborious alternative to hand-cranking, meant that this fracture had become obsolete in its original context. Starter motors had become largely ubiquitous by the end of the Great War.
Clay shoveler's fracture
Definition
Isolated avulsion fracture of the spinous process of the cervical / thoracic vertebrae (most commonly from C6 to T3) 11
Mechanism of injury
A violent-type hyperflexion injury of the neck, with resultant counterforce produced by the trapezius / rhomboid muscles or the supraspinous / interspinous ligaments 11
Historical context
Reginald Dalton Meckellar-Hall, an Australian orthopaedic surgeon, is widely credited for describing the clay shoveler fracture in 1933 12. He noted that labourers contracted to dig ditches in the Western Australian heat would not uncommonly experience a painful crack between the shoulder blades when tossing a loaded shovel filled with clay 13.
During the same point in time, on the other side of the world, the Autobahn was being laid down at an astounding speed. An influx of similar cases was reported in German road-workers where it was referred to as ‘Schipper’s disease’ 13.
Modern context
The classical definition of the fracture that is associated with manual work has become rare in modern times where excavators and other machinery have replaced shovels and hoes.
It can sometimes be seen in motor vehicle accidents, where abrupt deceleration forces resulting in significant neck whiplash can reproduce this injury 14.
Gamekeeper's thumb
Definition
Injury to the ulnar collateral ligament of the thumb 15
Mechanism of injury
Chronic repetitive hyperabduction movements of the thumb 15
Historical context
In 1955, C. S. Campbell documented a specific overuse injury pattern seen amongst Scottish gamekeepers who used their thumbs as a focal point to break the necks of rabbits and fowl 16. The repeated valgus stresses to the base of the thumb can result in chronic laxity of the ulnar collateral ligament (UCL) 17. Symptoms can include a weak pincer grip and pain over the metacarpophalangeal (MCP) joint 16.
Modern context
As opposed to a chronic degenerative condition, injury to the ulnar collateral ligament is seen nowadays in the form of an acute tear from a sporting injury. It is most commonly associated with skiing (‘skier’s thumb’) where an outstretched thumb, wrapped around by a pole strap, is trapped between the ground and the clasped ski pole during a fall 18.
An acute UCL rupture is often accompanied by an avulsion fracture at the site of its insertion, involving the ulnar side of the base of the proximal phalanx 18.
March fracture
Definition
Stress fracture of the second or third metatarsal shaft 19
Mechanism of injury
Chronic, repetitive abnormal stress placed on normal bone, resulting in bony remodeling and microfracture 20
Historical context
In 1855, the Prussian military physician Breithaupt was the first to describe stress fractures, approximately forty years before the invention of the X-ray 21. He observed that green military recruits, made to undergo strenuous physical exercises in training camps, would present with swollen painful forefeet, amid complaints of being unable to keep up with their peers 22. He would name this condition ‘Fussgeschwulst’ 23.
Whilst stress fractures can affect other bones, particularly in the lower extremities, the classical definition of the march fracture in its original context is as a metatarsal injury.
Modern context
Any occupation that involves prolonged periods of running or standing can cause metatarsal stress fractures. Whilst soldiers are still at risk of developing such an injury, they have also been documented in the civilian population, particularly amongst athletes such as marathon runners 24.
Paratrooper fracture
Definition
Isolated, undisplaced fracture of the posterior lip of the distal tibia (‘posterior malleolus’) 25
Mechanism of injury
Plantar flexion of the ankle joint at impact with high-energy axial load 25
Historical context
The Second World War saw the large-scale deployment of military parachutists (‘paratroopers’) as a novel tactic to enter the battlefield by air.
In 1943, American military physician William J. Tobin reported a new injury seen amongst paratroopers at the Parachute School in Fort Benning, the national parachute training camp for the U.S. Army 26.
He observed that when the foot is pointed downwards at the moment of impact, often when the trainee parachutist is incorrectly ‘reaching for the ground’, the landing force is transmitted through the foot to the posterior articular surface of the tibia, which is locked against the talus and can subsequently fracture 27.
Modern context
An isolated fracture of the posterior lip of the tibia is an uncommon injury pattern, only representing up to 1% of all ankle fractures 28.