Essex and Herts Air Ambulance Trust (EHAAT) is a publically-funded charity that operates two doctor-paramedic pre-hospital care teams to provide support to land ambulance crews in two counties in the South East of England. The service is predominantly helicopter-based but operates a rapid response car outside daylight hours or in poor weather. The total population covered numbers approximately 1.8 million. The team responds to major trauma and medical emergencies, with the latter accounting for approximately 20% of all missions. The paramedics who work for the service are all employed by the East of England Ambulance Service NHS Trust, and are seconded to EHAAT for a period of 24 months. A comprehensive selection process is undertaken and an extensive training programme covering aviation practice and extended clinical management is in place for successful candidates. In addition, EHAAT paramedics have been among the first to enrol and undergo enhanced skill training in anaesthetics and intensive care medicine as part of a postgraduate certificate in advanced paramedic practice in critical care. We believe that one of the strengths of the service provided by EHAAT lies in our paramedics acting as role models and ambassadors for both our service and the ambulance service in general.
The case
A 23-year-old woman who, while crossing the road, was hit by a car coming towards her from her right side. Witnesses reported that the car drove over the patient and dragged her a few yards down the road. Although a land ambulance paramedic had administered 10 mg of intravenous morphine and inhaled nitrous oxide for analgesia, the patient was still in severe pain and the crew on scene requested that the HEMS team be dispatched to provide further analgesia to help with splinting and transportation of the patient to an appropriate facility. On arrival of the EHAAT team, the police had closed the road to all traffic and the patient was lying on the road where the accident had occurred. The land paramedic crew had commenced oxygen therapy, applied a cervical collar and instituted manual in-line stabilisation (MILS). They had also inserted two peripheral intravenous cannulae and had given a fluid bolus of 500 mls. The patient was fully conscious, felt her breathing to be normal and had a good radial pulse. Apart from some minor abrasions, the only injury was a clearly swollen and deformed right thigh. There was a dent in the left front bumper of the car that hit her but no ‘bulls-eye’ in the windscreen or dent in the ‘A’ pillar. With full monitoring in place, including nasal end tidal carbon dioxide (ETCO2) measurement, procedural sedation with ketamine at a dose of 0.5 mg/kg was administered. This was followed by a fifteen-degree log roll onto an orthopaedic scoop stretcher (OSS) and application of both a pelvic splint (due to mechanism of injury) and a Kendrick Traction Device (KTD) (Kendrick EMS, Concord, North Carolina, USA) onto the right leg. Intact neurovascular status in the right foot was confirmed both before and after application of the KTD. After further packaging, including head blocks, tape and ear defenders the patient was flown to a receiving emergency department. Apart from a fractured right femur (Figures 1a, 1b, and 2), no other injuries were found on CT scanning.
Applied anatomy
The human femur is the longest and strongest bone in the body. It forms approximately one quarter of the person's height and can withstand 800–1100 kg of compression force without breakage (Encyclopaedia Britanica, 2007). The function of the femur is to transmit the load exerted, in the standing position, from the upper body onto the femoral head and neck and down to the tibia. A fracture of the femur implies a large force transmission through the patient. The proximal extremity consists of the femoral head, which articulates with the pelvic acetabulum, and the neck along with the greater and lesser trochanters. The shaft of the femur consists of a strong cylinder of bone with a bony ridge called the linea aspera adding strength to the posterior surface. A membranous layer of periosteum, which assists with bone growth and repair and also has a rich nerve and vascular supply, covers the outer surface of the shaft. Because of this anatomical arrangement, mechanisms of injury that induce axial torsion loading of the femoral shaft (such as when a patient lands awkwardly on one leg from a fall) produce spiral fractures and cross-bending loads (a direct anterior blow, such as from striking a car dashboard) produce transverse fractures (Evans et al, 1951). A branch of the femoral artery called the profunda femoris supplies blood to the femoral shaft. This sits in the linea aspera and supplies one or two nutrient arteries, which pass through the cortex of the femoral shaft and into the medullary area of the bone. These pass superiorly and inferiorly, anastomosing with metaphyseal arteries at either end of the femur. This supplies the inner two-thirds of the bony cortex while periosteal vessels supply the outer third. Venous drainage occurs through veins that pass alongside the arteries and through the bony cortex, especially at muscular attachments along the femur. This complex arrangement of blood supply partly explains the potential for haemodynamic compromise, even with a unilateral fractured femur. Sensory nerve supply to the periosteum is via the femoral nerve. This becomes important when considering local anaesthetic blockade of the femoral nerve in order to provide additional analgesia. This anatomy is demonstrated in Figures 3 and 4.
Discussion
Femoral shaft fractures (FSF) can occur via high- or low-energy mechanisms. High-energy FSF, such as those caused by road traffic collisions (RTCs) or falls from height are more common in young people and may be associated with multiple injuries. Conversely, those caused by low-energy trauma, such as falls from standing, are more common in the elderly due to osteoporosis and reduced bone regeneration. The elderly population may also suffer from an increased number of co-morbidities such as ischaemic heart disease and chronic obstructive pulmonary disease. In young children with an FSF, although accidental trauma does occur, non-accidental injury should also be considered.
In their Scandinavian study, Månsson et al found the incidence of FSF to be 12.2 per 100 000 per year and low energy trauma was the cause in 77% of cases (Månsson et al, 2006). These included elderly women, those that had had previous hip surgery and those falling from a height of less than six metres. Enninghorst et al in their Australian epidemiological study, which included all age groups and any pre-hospital deaths, noted an FSF incidence of 21 per 100 000 per year, with 51.6% caused by low energy trauma (Enninghorst et al, 2013). These included patients similar to the above categories but also a subgroup of younger patients with sports-related injuries.
Complex classification systems exist to describe the ways in which the femur fractures, but most are designed for formal descriptions and useful in-hospital operative planning. These classification systems are outside of the scope of pre-hospital practice. The most useful classification system to remember in the prehospital setting is the Gustilo classification of open fractures (Table 1) (Gustilo and Anderson, 1976). This grades the size of the skin wound and whether there has been any soft tissue loss or associated vascular injury. This affects patient management in terms of antitetanus prophylaxis and antibiotic prophylaxis, which should be administered as soon as possible but at least within three hours of injury (British Orthopaedic Association and Bristish Association of Plastic Reconstructive and Aesthetic Surgeons, 2009). Gross contamination should be removed from the wound but it should not be irrigated as a routine. If possible, and considering guidance on the use of patient photography, the wound should be photographed and then covered with a simple saline-soaked dressing. In line with locally agreed policies, patients with an open femoral shaft fracture and extensive soft tissue injury may benefit from direct transfer to a specialist hospital.
| Type I | Open fracture with a skin wound of <1 cm in length and clean |
| Type II | Open fracture with a laceration >1 cm in length without extensive soft tissue damage, flaps or avulsions |
| Type III | Open segmental fracture with >10 cm wound with extensive soft tissue injury or a traumatic amputation (special categories in Type III include gunshot fractures and open fractures caused by farm injuries) |
| IIIA | Adequate soft tissue coverage |
| IIIB | Significant soft tissue loss with exposed bone that requires soft tissue transfer to achieve coverage |
| IIIC | Associated vascular injury that requires repair for limb preservation |
The femur is the longest bone in the human body and is surrounded by a cylinder of soft tissue. Complete fracture of the femoral shaft allows the gluteal and iliopsoas muscles to flex the proximal fragment of bone, while the adductor muscles pull the distal fragment towards the pelvis. This forms a more spherical soft tissue envelope, which is of greater volume than the normal cylindrical one. Haemorrhage from associated soft tissue damage or disruption of the femoral bone blood supply is, therefore, correspondingly greater and can be as much as 1–1.5 litres in a closed fracture. This can be doubled in bilateral FSF and further increased if the fracture is an open one because of the absence of local tamponade effect. An extensive local inflammatory response can occur resulting from the soft tissue damage around the fracture site. This causes pro-inflammatory mediators to be released into the systemic circulation (Hauser et al, 1997), leading to increased capillary permeability and organ dysfunction, which may contribute to morbidity and mortality associated with FSF. Indeed, Kobbe et al noted that bilateral FSF was an independent risk factor for pulmonary failure (Kobbe et al, 2013). In addition, Oestern et al showed that bilateral FSF, when compared to a unilateral fracture, is associated with a compound, and not simply additive, increase in morbidity and mortality—16% with bilateral versus 4% in unilateral FSF (Oestern et al, 2001). Traction and splinting of the fractured femur to its original length helps reduce pain by reducing any soft tissue spasm and distraction of the fractured pieces of bone and periosteum. It also helps to control further haemorrhage by reducing the potential space of soft tissue (sphere to cylinder) within which to bleed.
Management of a femoral shaft fracture
Having confirmed scene safety and excluded massive haemorrhage from any associated injuries, the patient can be assessed in a CABCDE fashion, as per Advanced Trauma Life Support (ATLS®) guidelines (American College of Surgeons Committee on Trauma, 2013). Evaluation of the mechanism of injury may heighten suspicion that an FSF has occurred, even if the injury is not immediately obvious or the patient is unable to complain of pain. If the mechanism of injury has involved a motor vehicle, looking at the damage to the vehicle may give the rescuer an impression of the force vector that has caused the injury, and coupled with the knowledge of the anatomy and biomechanics of the femur, a fracture may be expected. Any airway or breathing problems should take priority but assuming, as in our reported case, it is an isolated femoral shaft fracture, the main management themes consist of external haemorrhage control, analgesia, reduction and splinting, immobilisation and ensuring distal neurovascular function is, or remains intact. As per the UK Ambulance Services Clinical Practice Guidelines for critical trauma, all patients with an FSF should have high flow oxygen via a non-rebreathe facemask instituted to target their oxygen saturations to between 94–98% (Association of Ambulance Chief Executives, 2013). This helps maintain oxygen delivery to damaged tissues. One, preferably two, large bore peripheral intravenous cannulae should be inserted to provide analgesia and, if required, fluids, should signs of cardiovascular compromise from haemorrhage be apparent. Administration of additional crystalloid is unnecessary in the absence of these signs and, as in the context of any bleeding, should be kept to the minimum required to maintain critical organ function, given at the appropriately titrated dose until surgical haemorrhage control and/or blood products are available. This helps avoid hypothermia, dilution of blood coagulation factors and disruption of any blood clots that may have already formed. The absolute circulating blood volume in the paediatric population is correspondingly smaller than that of an adult so haemorrhage from a paediatric FSF may result in greater cardiovascular compromise.
Analgesia should be multimodal. An appropriate dose of intravenous morphine should be administered and, if no pneumothorax or open head injury is suspected or present, Entonox (50% oxygen and 50% nitrous oxide) may be used liberally. Intravenous paracetamol, if carried, may also be given. If analgesia allows, gentle, sustained traction by pulling the affected leg out to length (compared with the unaffected leg) and then rotating to normal alignment, if required, is beneficial in terms of both pain and haemorrhage control as mentioned previously. The foot distal to the fracture site should be regularly examined for vascular (capillary refill time, dorsalis pedis pulse) and neurological integrity both before and after any movement of the limb. In cold environments where, on assessment, raised capillary refill times of the affected lower limb may be observed, comparison may be made with the unaffected lower limb to elucidate whether there is genuine vascular compromise or vasoconstriction from low temperature. The absence of a pulse, or other evidence of impaired perfusion should be regarded as a a limb-threatening emergency. Traction to reduce the leg into an anatomical position may improve perfusion and this should be clearly documented and regularly reviewed. If the pulse does not return despite traction, the patient should be transported as a matter of urgency, and the pulseless limb pre-alerted to the receiving emergency department. Application of a traction splint will free up the person who is maintaining leg traction. There are many different types (Table 2) but most rely on maintaining a distracting force between the pelvis and the ankle, with straps along the leg for support. If traction is applied to a splint, the amount of traction is usually around 10% of the patient's body weight up to a maximum of 6.75 kg (15 lbs) (per limb with femoral fracture if bilateral) (Månsson et al, 2006). In patients with less muscle mass, for example the elderly, lower amounts of traction may be applied to achieve the required effect (Borschneck and Spotts, 2002). If the splint does not have an integral measuring device, the amount of applied traction may be difficult to estimate. In this case, the traction required should be based on symptomatic control of the patient's leg pain and the injured limb being the same length as the uninjured limb, as mentioned earlier. However, regardless of the amount of traction applied to the leg, the level should be checked regularly en route to hospital because, in their experimental study, Månsson et al found that the force of traction that had been initially applied had reduced by 58% 30 minutes post application, with the fastest decline within the first 5 minutes (Månsson et al, 2006).
| Traction measurement capability | Bilateral femoral fracture splint with single device | Intact pelvis required | |
|---|---|---|---|
| CT-6 |
No | No | No |
| Donway Traction Splint |
Yes | No | Yes |
| Kendrick Traction Device |
No | No | No |
| Sager Splint |
Yes | Yes | Yes |
| Thomas Splint |
Yes (if weights used) | No | Yes |
| Hare Traction Splint |
No | No | Yes |
Complications of FSF (Table 3) may be categorised by time of development. Two complications that are not usually seen in the pre-hospital environment, if the patient is extricated and transported to hospital in a timely manner, are compartment syndrome and fat embolism syndrome.
| Time post injury | Complication |
|---|---|
| Pre-hospital | Pain |
| Early in-hospital management | Pain |
| Late in-hospital management | Infection |
Muscle groups of the leg are contained within fascial compartments. The fibrous fascial tissue is tough and non-compliant, helping to hold the muscle tissues in place. However, if the pressure in these compartments increases, for example from injury or a haemorrhage within the muscles, then venous blood flow may be restricted, leading to congestion and deprivation of the nerve and muscle tissues of oxygen and nutrients. If this occurs within the first few hours after an injury, it is a medical emergency known as acute compartment syndrome, requiring urgent surgical assessment and treatment. Symptoms may include pain out of proportion to that expected from physical examination of the patient and also occurring with passive movement of the affected muscle groups. Also, paraesthesia, initially in the distribution of any affected peripheral nerve, pallor and later, paralysis of the limb (Shears and Porter, 2006).
Fat embolism syndrome may occur with traumatic long bone injuries and is associated with pulmonary, cerebral and haematological symptoms and a petechial rash over the upper torso. Symptoms, such as dyspnoea, hypoxaemia, agitation and thrombocytopaenia, occur 1–3 days post injury and occur when globules of fat are released into the circulation. These initially cause obstruction to blood vessels but also, after hydrolysis of fat to free fatty acids, endothelial damage of the blood vessel walls occurs. Treatment is supportive with high flow oxygen to reduce hypoxaemia, fluid therapy to maintain circulating volume and early immobilisation of the fractured limb (Shaikh, 2009).
What can enhanced care teams offer?
Most patients with an isolated fractured femoral shaft can be treated with the simple measures outlined, and taken to the nearest trauma unit for further management. However, some patients may benefit from an enhanced care medical team such as the EHAAT team. These include patients who may have sustained other major injuries, those that are physically trapped and those that cannot be moved without further analgesia. Enhanced care from the EHAAT team may take the form of procedural sedation with intravenous or intramuscular agents, or peripheral nerve blockade with local anaesthetics, for example femoral nerve or fascia iliaca blocks. If there has been extensive soft tissue or bone loss, transfer to an ortho-plastics centre can be facilitated, particularly if a long distance transfer is required by air. Debate continues about in-hospital management of FSF and which patients benefit from early total care versus those that benefit from initial damage control orthopaedics and definitive treatment at a later stage, but this is beyond the scope of this article (Hildebrand et al, 2004).
Conclusions
We have described normal femoral anatomy as it relates to the clinical occurrence and presentation of femoral shaft fractures. Assessment and prehospital management of FSF has been discussed, as well as the support an enhanced care team such as HEMS may be able to offer in terms of further analgesia and transfer to appropriate facilities that may be distant from the scene.