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The Med Cell:
Dr Stefan Eriksson
The following information is for educational purposes only.
“bare feet are for bathing in, boots are for kicking in”
The foot is the first region of the body to be covered in the Med Cell series. It is one of the most important areas available to the combat practitioner for two opposing reasons. First, due to its structural properties, the foot is an extremely effective weapon, and is employed frequently in martial combat. Conversely, the injured foot can have devastating consequences to the victim. As a structure subjected to essentially constant weight bearing, the foot reacts very differently to even small degrees of bone or joint mal-alignment that are easily tolerated, for example, in the hand or other non-weight-bearing or low-stress joints. In fact, of all traumatic orthopedic injuries encountered in the emergency department, foot and ankle injuries appear to result in higher functional loss than any other orthopedic injury does (including all 4 extremities and the pelvis). Put the foot out of action and the whole lower limb on that side becomes useless. It follows that adequate footwear is important (especially in military settings), as is proper care and maintenance of the foot.
Foot injuries are common among athletes, especially those engaging in martial arts or combat. According to a survey conducted in Victoria, Australia, between 1995 and 2000 there were 600 presentations to Emergency Departments as a result of injury sustained during martial arts practice. 91 (15.2%) of these presentations involved the foot (including toes).
This article will follow the format below:
- Anatomy and description of Gait
- Combat Injuries ( patterns and mechanisms) will be grouped according to location, i.e. hindfoot, midfoot and forefoot
- Ballistics primer and Gunshot Wounds
- Environmental Injuries relevant to combat
Anatomy of the Foot
The foot is a very complex structure
- 28 Bones
- 31 Articulations
It is simpler to think of the foot as being divided into 3 regions.
- Forefoot: Phalanges (toes), sesamoids and Metatarsals
- Midfoot: Cuneiforms (medial, intermediate, lateral), Cuboid and Navicular bones
- Hindfoot: Talus and Calcaneus
(Bones of the midfoot and hindfoot are collectively referred to as the Tarsal bones)
As mentioned, there are 31 articulations in the foot. However, the joints essential for proper foot function are subtalar, talonavicular, and lesser metatarsophalangeal (MTP) joints. The remaining joints can be malfunctioning yet have little effect on foot function.
The normal human gait can be broadly divided into two phases, stance and swing phase. Stance phase commences with the heel striking the ground and ends when the toes push off and the foot loses contact with the ground. During the swing phase the leg swings forward and does not come into contact with the ground. The stance phase is then repeated.
- stance phase makes up 60% of the gait cycle
- swing phase makes up the remaining 40% of the gait cycle
Proper functioning of the foot is required for normal gait. It is the intention of combat strikes to the foot to disrupt this mechanism, so impairing the ability to walk.
A more comprehensive description of gait can be found here: http://www.oandp.org/jpo/library/1997_01_010.asp
The weight of the body is supported by the foot, and is transmitted and distributed over 6 areas; the calcaneus in the heel, the sesamoids of the first metatarsal head, and the 2nd, 3rd, 4th and 5th metatarsal heads.
During normal gait the foot supports loads of up to 7 times bodyweight, and during barefoot gait, the forefoot actually encounters three times as much load distribution as the hindfoot.
Diagram 1 Contact points of the sole of the foot during normal weight bearing.
Consequently, these areas absorb a large amount of energy during walking and running. It follows that these contact points are crucial to striking during close combat. The foot stamp and axe kick when performed correctly transmit force to the opponent through the contact points illustrated above - usually the calcaneus, being one of the most dense bones in the body. This emphasises the importance of hard soled boots in combat.
Despite this strong component, when trauma victims fall onto their feet from a height, the result is usually (bilateral) calcaneus fractures. It is known as the “Don Juan syndrome”, though only Don Juan in the movies can jump from a balcony, land on his feet and walk painlessly away. In the gulf war, a large number of foot and ankle injuries were the result of parachute jumps by servicemen wearing full combat loads of gear. In more serious falls, the fractures extend upwards to the knees, hips, pelvis, lumbar and thoracic vertebrae, and in some instances, the cervical vertebrae can punch through the base of the skull into the brain.
Lets now examine each foot region in turn beginning with the Hindfoot
- extremely dense bone, therefore fracture suggests extremely high force of impact
- gunshot wounds, explosive fractures from mines or shell fragments
- during the Croatian homeland war (1991-1993) at Zagreb medical centre, 1643 patients were treated for gunshot or explosive injuries. Of these, 28 had trauma to the talus, with only one recovering fully at 3 yr follow-up, i.e. a devastating injury
- only bone to directly link foot to the lower leg
- responsible for transferring all weight from body to the foot, and responsible for ankle flexion and extension, hind foot inversion and eversion, pronation and supination, and push off portion of the gait cycle
- articulates with the tibia, fibula, calcaneus and navicular
- no muscular or tendinous attachments
- 15-20% are open fractures
Talar neck and anterior body fractures are the most common
- 50% talar fractures
- usually result of motor vehicle accident or fall, when the foot is dorsiflexed and an axial force is applied (the foot is in this position when resting on the accelerator pedal in a car)
- also caused by forced inversion or eversion or rotation
Talar head fractures less common
- mechanism is a compressive axial force, or extreme dorsiflexion
- commonly associated with partial dislocation or subluxation
- account for 25% of talar fractures
- caused by twisting type spain
Lateral process fractures
- inversion injury “snowboarder’s fracture”
- normal range of motion 25-30 degrees inversion, 5-10 degrees eversion. This implies that forcibly inverting someone’s foot greater than 30 degrees or everting it greater than 10 degrees can cause subtalar dislocation
- injuries a continuum from sprain to complete dislocation
- subtalar dislocation is the simultaneous dislocation of the talocalcaneal joint and the talonavicular joint
- high energy mechanism three quarters of the time
- can dislocate in any direction
- medial dislocation caused by inversion (80%). Sometimes called “basketball foot” as this is a common mechanism
- lateral dislocation (15%) caused by eversion (poorer prognosis as more force required)
- can mimic ankle dislocation
- surgical emergency as blood supply to region disrupted, requires prompt reduction
XRAY 4 Subtalar dislocation. Note the talus (T) has shifted posterior away from the navicular (N) and calcaneus C. This was the result of twisting the foot inwards (inversion injury).
- 2% of all fractures
- 60% of all tarsal fractures
- usually caused by sudden high velocity impact to the heel e.g. MVA, falls (usually greater than 6ft)
- can be the result of an explosion e.g. landmine through the floor of a vehicle
- can also be caused by twisting or avulsive (tearing or pulling) force
- 75% intra-articular, 25% extra-articular
- poor prognosis
- 10% result in compartment syndrome (see section below on compartment syndrome)
- Relatively rare, as midfoot very stable due to ligamentous attachments
- mechanism forced eversion, inversion, plantar flexion, dorsiflexion, or direct force
- rarely involve only one bone
- often associated with Lisfranc injury (see below)
Lisfranc Injuries (Tarsometatarsal injuries)
- - commonly called Lisfranc fractures after one of Napoleon’s army surgeons, Jacques Lisfranc who described the injury sustained when a rider fell from his horse with his foot trapped in the stirrup
- relatively rare, but extremely debilitating. Nobody with a Lisfranc injury will ever walk properly again
- often have associated dislocations
- mechanism is either
- Sudden torque on the foot (a runner falling into a hole)
- Axial loading (e.g. rugby player with forefoot fixed on ground, dorsiflexed, and another player landing on the heel),
- Direct Trauma (dropping heavy object onto foot), usually open fractures.
- makes up part of the important talonavicular joint, the key joint that allows pronation and supination.
- talonavicular joint also works with the talocalcaneal joint to allow inversion and eversion of the hind foot as the foot adapts to uneven terrain
Two types of fractures
- Acute fractures
- rarely isolated to just the navicular
- equally divided between avulsion fractures which occur when the foot is plantar flexed AND inverted or everted, and body fractures when a high energy axial force is applied
- Stress fractures of the navicular (more common)
- occur frequently in running and jumping athletes
(See section on stress fractures)
- occur frequently in running and jumping athletes
XRAY 7 Navicular fracture after being stomped on. Undisplaced fracture. This highlights the susceptibility of the dorsum of the foot to being injured if inappropriate footwear is used in combat.
Other midfoot bones
The cuboid and cuneiform bones are rarely fractured in isolation, but can be disrupted as part of a larger injury such as that resulting from an explosion or car accident.
This section is detailed as these injuries are encountered frequently in combat.
Metatarsal fractures are among the most common traumatic injuries to the musculoskeletal system.
They account for:
- 35% of all foot fractures
- 6 % of all foot injuries
- 5%of all fractures
- 1 in every 500 emergency department presentations
Mechanism of injury
- Direct Trauma e.g. foot stamp to top of foot
- Indirect Trauma e.g. foot pinned and lateral force or twisting motion applied.
- Overuse (stress) injury e.g. so called ‘march fracture’
Overall, fractures are usually the result of direct trauma. However, exceptions are fractures to the fifth metatarsal and stress fractures.
Single traumatic fractures are usually non-displaced due to the restraining forces of the surrounding ligaments.
Because there is little in the way of tissue on the dorsum (top) of the foot to protect the metatarsal bones, they are particularly prone to crushing injuries. This is important to the combatant as they make an easy target , especially if the opponent is wearing flimsy shoes or is barefoot. Martial artists frequently injure the dorsum of their foot when kicking with this region which is why this style of kick is not employed in military combat.
- carries up to twice the load of each of the other four metatarsals
- carries more than 3 times body weight during propulsion
- fractures usually result of direct trauma
- usually open or comminuted
Second, Third and Fourth Metatarsals
- fractures can be due to direct trauma as in a direct blow, or indirect trauma as in twisting
- direct traumatic fractures here are often open and comminuted or transverse, while indirect trauma usually results in a spiral fracture
- stress fractures common (see section on stress fractures)
- one quarter of all metatarsal fractures
- unique compared to other metatarsals as they have tendons that are extrinsic or arise outside the foot itself (meaning the fifth metacarpal can be fractured when twisting the ankle as in avulsion fracture below), and there is very little soft tissue coverage over the plantar-lateral aspect leaving it prone to traumatic forces.
- more flexible and less crucial to weight bearing than the other metatarsals
- four major types of fractures; avulsion, Jones, stress, shaft fractures
1. Avulsion Fracture
- most common
- peroneus ligament pulls off a fragment of bone during inversion when the foot is plantar-flexed
Diagram 2 below: C = Calcaneus, T = Talus, Cu = Cuboid, 5th Met = 5th Metatarsal, Ligament = Peroneus Ligament. The drawing depicts an inversion injury i.e. rolling the foot over. The peroneus ligament stretches, and avulses or tears off the base (shaded red) of the fifth metacarpal. It is demonstrated in the x-ray below the drawing.
2. Jones Fracture
- inversion injury like avulsion fracture BUT there is an upwardly directed force or blow to the planted fifth metatarsal
3. Stress Fracture (see section on stress fractures)
4. Shaft (diaphyseal) fractures
- fracture in the shaft or distal end of the fifth metatarsal.
- mechanism is usually rolling over on the outer border of the foot while standing on the ball of the foot with the ankle fully plantar-flexed
- can also occur when falling or jumping from a height
- occasionally fractures through the heads of the metatarsals are multiple and result from a direct blow from either side of the planted foot causing abduction or adduction of the region e.g. a kick to the insole when planted.
Due to the high incidence of these injuries in sports/combat, a brief diagnostic technique follows:
- Most people with metatarsal fractures can pinpoint the exact site of the fracture
- In the acute setting, bend each toe backwards and press on the base of each toe (axial loading). Palpation (pressing) over the length of each metatarsal can also establish diagnosis.
- Simple closed injuries can (mostly) be managed with a stiff sole boot
- Open injuries, multiple fractures, severe displacement and compartment syndrome usually require surgical intervention
Metatarsophalangeal (MTP) joint injury
- axial loading during hyperextension, or when the toe is hyperdorsiflexed
- result in stretching or tear of the capsule surrounding the joint
- “turf toe”
- precipitating factors can be flexible soled footwear (or bare feet), and soft gym mats.
- in severe cases fractures/dislocations occur
- almost unique to take-down moves, occurring when toe is bent under after dropping to one knee to throw
- also when sparring and changing directions rapidly
- treatment simply hard soled boots to limit dorsiflexion for a few weeks, unless moderate to severe injury
Injury to the proximal phalanx and first ITP joint
- different anatomy to other metatarsals and ITP joints
- fracture mostly caused by direct trauma, e.g. dropping a weight onto the foot or stubbing the big toe causing axial loading
- treatment is buddy strapping unless compound fracture
- dislocation usually result of jamming toe
Injury to the lesser phalanges and ITP joints
- dislocation rare
- fractures usually result of stubbing toe - so called “night walker’s fracture”
- buddy strapping is treatment of choice for most toe fractures
Injury to the distal phalanx and nail bed
- fractures to distal tuft almost always crushing injuries
- commonest nail bed injury is subungual hematoma (blood blister under the nail)
- if a subungual hematoma occupies less than 25% nail bed then should be drained with heated paperclip under sterile technique and kept clean for 48 hours
- if a subungual hematoma occupies greater than 50% of nail bed means nail bed laceration 2/3rds of the time and often fracture of the phalanx
- in severe crushing injuries, the nail bed and matrix may be disrupted leading to loss of the nail.
- nail ripped off, either completely or partially
- usually from direct or glancing hits to the (mostly big) toe
- long toenails a risk factor
- can require 4-5 months to re-grow at 1mm per month
- if nail-bed laceration or fracture then requires professional medical attention
Since all stress fractures follow the same basic cause, diagnosis and treatment, they will be discussed as a group, though the information here applies to any particular bone with a stress fracture.
Stress fractures result from the cumulative effect of repetitive micro trauma that is insufficient to cause an acute fracture, but eventually leads to stress failure of the involved bone.
- i.e. overuse injury or fatigue fracture
- common in athletes and military recruits
- 95% of all stress fractures involve the lower limb
- incidence decreases with age according to a study of Israeli military recruits
- A study of 205 soldiers by Milgrom et al showed 184 stress fractures of the lower extremity, 7.6% of which were of the metatarsals.
- Up to 20% (11% 2nd metatarsal) of stress fractures in athletes and 23% in military recruits are located in the metatarsals
- usually result from participation in new activity or increase in intensity of activity
Order of frequency, from most common to least common:
Tibia, 2nd metatarsal, 3rd metatarsal, 5th metatarsal, desmoids, navicular, femur, fibula and pelvis
Left untreated, stress fractures can progress to displacement with malunion, and subsequent foot deformity or poor weight bearing capacity.
Important limb threatening and life threatening condition that occurs as a result of swelling within a confined anatomical space (or compartment).
- can occur with injury to any fascial compartment
- compartment confined by thick fascia
- usually caused by fracture, dislocation or crushing injury, but also penetrating wounds
- increased pressure from muscle swelling or fluid accumulation (e.g. haemorrhage of blood or leakage of extracellular fluid) within the compartment
- increased pressure results in nerve and muscle damage or destruction
- can ultimately lead to kidney failure and death
- surgical emergency requiring an operation usually within 12 hours before irreversible damage occurs
Foot has 9 anatomic compartments
- calcaneal fractures have 1 in 10 incidence of compartment syndrome
- symptoms include pain out of proportion to the injury, especially when the muscles are extended
Gunshot wounds to the foot
Before looking at gunshot wounds to the foot, it is important to understand some basic concepts which can then be applied to other parts of the body.
“Science of motion of projectiles”
- Wound severity is directly related to the amount of kinetic energy imparted to the tissue by the bullet
- Doubling bullet size doubles energy, doubling bullet velocity quadruples energy
- Firearms can be classified as low velocity or high velocity
- If bullet enters the body but does not exit, then all the kinetic energy has gone into wound formation
- If a bullet enters the body then exits, then only some of the kinetic energy has gone into wound formation.
(which is why through and through gunshot wounds are often less lethal than gunshot wounds with no exit point)
As a bullet moves through the body, it crushes and shreds surrounding tissue. It also forces tissue outwards, creating a temporary cavity larger than the diameter of the bullet.
- low velocity firearms (700 - 1500 ft/sec),e.g. handguns, less likely to create temporary cavity
- high velocity firearms (1500 - 4000 ft/sec), e.g. centrefire rifles, create a large temporary cavity
This cavity lasts a very short time, but depending on the site, a significant amount of injury can occur.
- tissue that is elastic such as muscle will have significantly less damage than the liver which is the same density but less elastic. The permanent cavity will thus retain the size of the temporary cavity.
As the bullet passes through the body, it will yaw. In other words, it starts out in the point forward position, rotates through to 90 degrees where most tissue damage occurs, and then continues to rotate through to a complete 180 degrees with the base forward and thereafter continues to travel base forward (centre of gravity at the base). This is assuming it does not fragment beforehand in which case greater tissue destruction occurs. (Di Maio)
Diagram 3: In (1), the bullet enters the body, point forward. As it travels through the body, it begins to yaw (2), until it reaches its maximum width at 90 degrees (3). Here tissue destruction is greatest, as is cavity size. Finally in (4), the bullet faces base forward and continues like this until exiting or coming to a stop inside the body.
Finally, as mentioned, fragmentation can occur. This comes about either through inherent bullet characteristics (e.g. soft-point or hollow-point from a centre-fire rifle), or through striking bone. The fragments fly off in different directions acting as secondary missiles and so contacting more tissue to increase the size of the wound. A hollow-point bullet that mushrooms can increase its diameter 2.5 times on impact and will increase the area of tissue crush 6.25 times compared with a nondeformed bullet.
Gunshot wounds can be divided into four categories based on the distance between muzzle and target
- Contact wounds; muzzle held against body at time of discharge
- Near contact wounds; muzzle held very close but not touching the body
- Intermediate wounds; muzzle held sufficiently close to result in powder tattooing, but further than near contact wounds
- Distant wounds; muzzle held at a distance that will not result in any marks other than that caused by the bullet entering the skin
Gunshot wounds to the foot are usually the result of low velocity firearms discharging while being cleaned or loaded.
- The dorsum of the foot is more usually affected
- Fractures usually comminuted, open, and involve the joints
- Boucree and colleagues reviewed 101 patients with gunshot wounds to the foot. Eighty-one patients sustained fractures, and 20 had only soft tissue injuries. There were 91 low-velocity, 7 shotgun, and 3 high-velocity wounds.
- infection likely even with antibiotics.
- nonfreezing cold injury
- term comes from soldiers in WW1 standing in water filled trenches for days and getting this injury
- also common among soldiers during the Vietnam war
- poorly trained, tired, frightened, and dehydrated soldiers with thin socks and tight-fitting boots who are deployed in a cold and wet environment are unable to maintain foot care because of the battle setting. After several days of exposure, they are able to rest in a warm tent and remove their boots, where they begin to manifest the first stages of trench foot (Auerbach)
- tight boots constrict the blood vessels leading to poor perfusion and ultimately tissue death
- marching makes the condition worse
- water temperature normally 0-10 degrees Celsius
3 phases (note, hyper- = excess, -emic means blood)
- Pre-hyperemic phase: “cold and numb”, foot is white/yellow and cold to touch
- Hyperemic phase: hot, painful and swollen, can last up to 10 weeks. Muscles, nerves and arteries damaged
- Post-hyperemic phase: alternating pain and numbness, nerve and muscle wasting leads to loss of motor control which affects gait that can last a lifetime.
Acute treatment is drying and slight elevation of the foot.
Long term prognosis is poor.
Prevention is the key
A future article will look at cold injuries, specifically frostbite
The foot, although a potent weapon if utilized correctly, is prone to serious injuries, many of which are permanently debilitating. The following mechanisms of injury when applied by the combat practitioner can result in injuries as outlined above:
1. Foot stamp to top of foot when foot flat on ground
- soft tissue injury
- navicular fracture
- lisfranc injury
- fractures to any or all metatarsal bones
- fractures to any or all phalanges
- nail bed injury
2. Kick to side of foot from either direction when foot fixed
- Lisfranc injury
- navicular fracture
- metatarsal fractures
- toe dislocations
3. Inversion injury e.g. applying force to the lateral aspect of the foot or ankle when it is fixed to the ground
- Talar fracture
- Subtalar dislocation
- Lisfranc injury
4. Eversion injury e.g. applying force to the medial aspect of the foot or ankle when it is fixed to the ground
- Talar fracture
- Subtalar dislocation
- Lisfranc injury
- fracture to base of fifth metatarsal
5. Strike to heel when foot plantarflexed on ground I.e imagine soldier lying prone in shooting position, with toes on ground, then striking his from above
- talar fracture
- subtler dislocation
- Lisfranc injury
- “turf toe
6. As above, but a direct strike to the heel pad (unlikely if other soldier wearing heavy soled boots)
- calcaneal fracture
Re-reading through the article should enable readers to anticipate other injuries based on the direction of force applied when the foot is in various positions.
Lastly, a reminder why bare feet are not used for combat. This photo appeared in the last article but is worth showing again. The deep laceration resulted from stepping on broken glass and required surgical repair of the tendons.
In the next issue we will examine ankle injuries in combat.
Auerbach: Wilderness medicine, 4th ed, Mosby 2001
Browner: Skeletal Trauma; Basic Science, Management and reconstruction, 3rd ed
Saunders Press 2003
Di Maio, VJM: Gunshot wounds: practical aspects of firearms, ballistics, and forensic techniques, 2nd Ed, CRC Press 1999
Emergency War Surgery, 3rd United States edition 2004, Borden Institute Military Sudies
Grants Atlas of Anatomy, Agur, Ed, 10th ed, Lippincott, Williams, and Wilkins Pub 1999
Injuries associated with the martial arts, from the Victorian Emergency Minimum Dataset 2001
Mason, JK and Purdue, BN The Pathology of trauma, 3rd Ed, Arnold Publishers 2000
Milgrom et al J. Bone Joint Surg.Br. 1985; 67:732-5