12.9 Combined vascular and orthopaedic injuries

Severe fractures and dislocations commonly cause injury to adjacent vascular structures. Certain patterns of injury such as femoral shaft fractures injuring the superficial femoral artery, popliteal artery injury after knee dislocation, and brachial artery injury after supracondylar fracture of the humerus are frequent because of the close anatomical relationship between certain blood vessels and bones or joints.

The major determinant of outcome following arterial injury is the early recognition of the possibility of vascular damage and its prompt investigation. This can be difficult as some arterial injuries can be caused to the intima of the artery alone with no obvious external bleeding or haematoma. Initially the perfusion of the limb can appear to be normal (even pulses can be intact) with thrombosis of the artery occurring several hours after presentation of the patient. Frequent reassessment of the distal vasculature in patients with fracture patterns that often injure blood vessels is necessary to prevent late diagnosis and the risk of limb loss or loss of function.

Major veins can also be damaged either in tandem with an arterial injury or as an isolated event. Venous injury rarely requires operative intervention but does raise the risk of later deep vein thrombosis (DVT) and subsequent ongoing morbidity from post-thrombotic limb syndrome.

Penetrating injuries causing both vascular and orthopaedic injuries usually result from gunshot wounds. A low-energy transfer missile ordinarily damages a vessel lying directly in its path and bony injury may be no more than the equivalent of a ‘drill hole’ (Figure 12.9.1). On the other hand, a high-energy transfer wound with a bullet striking bone will have an impact velocity which shatters bone into fragments producing secondary missiles which cause further injury (Figure 12.9.2). A cluster of pellets from a shotgun fired at close range will produce a concentrated ‘spread’ causing large defects in soft tissue and severe comminution of bone, as well as contamination from the wadding and clothing, features which are often underestimated on superficial inspection. The vascular and bony injuries caused by shrapnel and secondary missiles in bomb explosions may be further complicated by crush injury from falling masonry.

The severity of vascular injury resulting from blunt trauma—as observed following sudden deceleration in road traffic collisions, in falls, and in rail, air, and mining disasters—often exceeds that caused by penetrating agents. The shearing forces generated by violent angulation of fractures may cause sharp bony fragments to lacerate or sever adjacent vessels (Figure 12.9.3) and indirectly stretch vessel segments at points of relative fixity, causing thrombosis. In posterior dislocations of the knee, the avulsive forces involved may result in tearing of tissues and in the process the layers of the popliteal artery, beginning with the intima, disrupt progressively. The dislocated knee has a tendency to reduce spontaneously, and notoriously the vascular injury may remain unsuspected and unrecognized on examination. In such cases, damage to the collateral system around the knee joint heightens the effects of ischaemia caused by popliteal artery injury. Fractures of the tibia associated with dislocation of the knee carry a vascular injury rate approaching 40% with a high risk of subsequent amputation if the injury is not recognized immediately.

In severe type IIIc open tibial fractures a constellation of factors inevitably combine to thwart success and are responsible for quite high amputation rates. In these cases, not only is there comminution of the fracture with bone defects and periosteal stripping but also severe muscle and skin loss, nerve trauma, and contamination compounded by injury to long segments of popliteal and crural vessels as well as collateral systems.

All these features may be found in blunt arterial trauma of the upper limb. In axillary vessel traction injuries the brachial plexus is also commonly affected.

A variety of vascular injuries may occur in association with fractures and dislocations. These may be injuries in continuity, partial tears, or complete tears. True traumatic spasm is quite rare and ought not to be presumed, with at least some intimal damage present in most instances of ‘spasm’, in some cases permitting flow transiently before progressing to thrombotic occlusion (Figure 12.9.4). An intimal fracture may develop into an intimal flap, which in turn may lead to dissection and intramural bleeding, and in cases where the intimal tear is circumferential, thrombosis is common. The key message for the orthopaedic clinician is never to assume that loss of a pulse distal to a major fracture is due to ‘arterial spasm’, nor to assume that if a pulse is present on initial presentation that vascular damage is completely ruled out.

A lacerated artery, is usually unable to contract and in open injuries may cause rapid exsanguination. If it seals, a false aneurysm may develop which may present with later rupture (Figures 12.9.5 and 12.9.6). Concomitant injury to the adjacent artery and vein may produce an arteriovenous fistula (Figure 12.9.7), with or without an adjacent false aneurysm. On occasions fistulae can compromise flow to a limb; or in the long-term a proximal fistula may provoke a high-output cardiac state.

When a vessel is completely transected by a missile or a shard of metal, the free ends tend to constrict, retract, and become sealed by a plug of thrombus. This process is also seen in traction injuries, such as posterior dislocations of the knee, in which the avulsive forces stretch the intima until it fractures and curls back on itself, the media and adventitia disrupt, the ends constrict, and thrombosis ensues. This does not occur in partial lacerations and can be associated with greater blood loss.

Venous injuries generally remain unrecognized until surgical exposure of an arterial injury. Those vein injuries sustained in blunt trauma do not easily lend themselves to repair.

Arrest of arterial flow causes tissue hypoperfusion and hypoxia which, in some cases, is further compounded by hypovolaemic shock and vasoconstriction. Striated muscle has a low tolerance for continuing warm ischaemia and after 6–8h, depending on the degree of injury and availability of collateral flow, muscle death occurs.

The restoration of blood flow after a period of ischaemia may cause the complex biochemical and cellular pathophysiological changes of ischaemia–reperfusion injury. Clamping or ligation of an adjacent injured main vein aggravates this process, as will the presence of associated bone and soft tissue damage (Figure 12.9.8). The extent of ischaemia–reperfusion injury is directly proportional to the severity and duration of striated muscle ischaemia. Ischaemia–reperfusion injury of a large mass of skeletal muscle has systemic implications, provoking multiple organ failure. An unrelieved rise in pressure may result in the development of compartment syndrome and ischaemic nerve damage. Again, the key point for the clinicians is not to assume that once the vascular reconstruction has been completed that everything will be fine—there is still the possibility of complications developing—particularly compartment syndrome and DVT.

In the multiply injured patient, resuscitative measures are taken to ensure an adequate airway, satisfactory ventilation, and correction of hypovolaemic shock. In many cases the orthopaedic team may be leading a resuscitation team and will therefore need to manage arterial or venous injuries in the acute phase until a vascular surgeon arrives. Many of these complex limb injuries are obscured by splints and bandages on first arrival. External bleeding should be controlled digitally and then by means of a pad and bandage. If arterial forceps or clamps are applied incorrectly they are likely to damage both vessels and nerves in the vicinity. Tourniquets tend to be poorly applied, often in a manner which accelerates the rate of bleeding, and if left unreleased will cause irreversible tissue and nerve damage. Information from bystanders as to the nature of the wounding agent, the amount of blood lost, and the time interval since injury will help in further decision making. Tetanus toxoid, prophylactic antibiotics, as well as appropriate analgesia, should be routinely administered.

A number of questions have to be answered in assessing the location, degree, and extent of vascular injury accompanying orthopaedic trauma:

If the answers to these questions are neither clear nor unequivocal, further investigation is required.

Doppler ultrasound pulse waveforms, segmental pressures, and ankle–brachial pressure indices may provide an early assessment of the presence of vascular injuries particularly in cases of blunt trauma, but should not be relied upon to definitively exclude injuries. In open injuries ultrasound is usually impractical.

Angiography either delineates an arterial injury or excludes its presence (Figures 12.9.9 and 12.9.10). In the latter case it gives the surgeon the confidence not to intervene, preventing unnecessary exploration). When clinical signs are equivocal, angiography is advisable. The medico-legal consequences of missing an arterial injury leading to subsequent limb loss are obvious. Angiography is of particular importance in blunt injuries which cause instability or dislocation of the knee, sometimes in association with displacement of a fracture close to the knee. Even when distal pulses are palpable, the chance of an occult arterial injury going on to occlusion and loss of the limb remains, and therefore this condition demands a policy of routine angiography.

If angiography is likely to be delayed and an arterial injury is suspected clinically, it may be preferable to take the patient to the operating room and perform a one-shot single-plate on-table angiogram followed by urgent repair of the arterial injury. Timely angiography may also prevent disaster in cases of persistent ischaemia after reduction of a fracture, especially in the elderly atherosclerotic patient. Many hospitals now have facilities for CT or MRI angiography. The advantage of these modalities is that, particularly CT angiography, may be obtained quickly and allow for some visualization of the bone and surrounding soft tissue. If clinical doubt exists despite imaging that does not show an injury then meticulous and repeated clinical examination should be performed and, if necessary, surgical exploration to resolve any doubt of arterial injury.

In injuries involving fractures and vascular trauma it is important to abbreviate the period of ischaemia and minimize ischaemia–reperfusion injury following arterial repair. Control of bleeding, resuscitation, and surgical treatment should be overlapping rather than sequential stages of management. Life-threatening injuries of the head, chest, and abdomen naturally deserve priority, but delay in dealing with limb vessel trauma may result in a poor outcome. Even if the complex vascular injury is isolated to a leg, surgical intervention still requires adequate time for exposure, wound care, bone fixation, and repair of artery and vein.

Time pressure, should not progress to rushed surgical practice. Wound care and cleaning should be performed correctly and all repairs, be that of the vessels or damaged bones carried out meticulously. Stabilization of a fracture prior to repair of injured vessels deserves consideration. Some of the pain is relieved, movement of loose bone fragments ceases to injure the vessels and soft tissues, optimal lengths of graft are used to repair the vessels, and confidence is instilled by the knowledge that artery and vein repair will remain secure from disruption. However, this sequence of surgical action delays restoration of flow and correspondingly has an impact on the degree of ischaemia–reperfusion injury.

This time pressure may be relieved by using shunts for both artery and vein on exploration of the wound. The arterial shunt restores perfusion, minimizes ischaemia–reperfusion injury, and reduces compartment pressure. The venous shunt re-establishes drainage and further helps to prevent a rise in compartment pressure.

Standard longitudinal incisions are employed for access to vessels of the upper and lower limb. A posterior gentle S-shaped incisional approach to the midpopliteal artery is acceptable in some penetrating injuries. In the case of blunt trauma associated with instability of the knee, a medial approach, accepting some compromise to the integrity of the knee, is preferable. The injured vessel is controlled first by digital pressure and then by suitable vascular clamps applied to segments exposed on either side of an artery and vein injury. The damaged vessel must be adequately excised to leave pristine ends for suture. The proximal artery is released to flush out thrombus and a balloon catheter is used to retrieve clot from the distal vessel, a process which can be assisted by milking the limb upwards, especially when surgery is delayed. Heparinized saline (20IU/mL) is then perfused into the distal limb.

An indwelling shunt in a transected femoral or popliteal artery (Figure 2.9.11) immediately restores flow, buying valuable time for precise operative work. An outlying shunt should be considered for an extensive wound within which lengthy segments of vessel have been destroyed (Figure 2.9.12). An indwelling venous shunt in a severed adjacent vein (Figure 12.9.11) re-establishes venous drainage and will also discourage thrombosis. If the vein is simply clamped, an acute and unacceptable rise in compartment pressure will occur, invariably necessitating fasciotomy. In some multiply injured patients, the vascular surgeon, working alongside other specialists involved in life-saving surgery in the head or torso, may be able to place shunts in vessels in wounds of a lower limb, assuring its survival until definitive vascular repair some time later. A range of shunts are available and the surgeon should choose one which with they are familiar.

The placement of shunts allows for ample time to survey the wound, identify nerve injury, remove debris, and irrigate the tissues. Restored arterial and venous flow provides sharper and more reliable demarcation between dead and viable tissue. Meticulous excision of nonviable tissues and debridement is especially essential in high-energy injuries. Free bone fragments and foreign bodies are removed, followed by copious irrigation, particularly in open contaminated wounds, a process which is of value in significantly lowering the concentration of the bacterial inoculum.

In the critically injured but neurologically intact limb (Figure 12.9.13A) restoration of flow by means of shunts (Figure 12.9.13B) will assist the surgeon in coming to a decision as to whether primary amputation may be more sensible than an attempt at major reconstruction.

The use of long intravascular shunts in artery and vein (Figure 12.9.13B) will provide the necessary slack for the liberal manipulation of the bone fragments. At this stage the orthopaedic surgeon proceeds to restore skeletal integrity. He is under no pressure to compromise technique and will be guided solely by a desire to achieve the best possible orthopaedic outcome.

Minor arterial injuries identified preoperatively may be amenable to treatment by endovascular means allowing the orthopaedic surgeons to proceed with bone stabilization in the presence of treated vascular injuries. Most injuries will not be suitable for endovascular repair in the trauma environment and will require open surgical repair. A variety of techniques may be employed by the vascular surgeon with the guiding principle of restoring both arterial and venous integrity in as many cases as possible. In lower limb injuries vein for repair should be harvested from the contralateral limb, particularly if there is damage to the deep venous system of the affected limb. If concomitantly injured artery and vein have not been shunted, the artery should be repaired first. If both vessels have been shunted, the order of repair is entirely immaterial.

It is worth remembering that repair of a damaged vein not only renews free venous drainage but also enhances the patency of an adjacent arterial repair. Moreover, the likelihood of thrombosis, oedema, and chronic venous insufficiency is minimized. In a very small number of cases the development of limb-threatening venous gangrene is averted.

The success of a vascular repair is dependent on achieving satisfactory vessel cover and the elimination of dead space by viable adjacent soft tissue and muscle. As shunting will have provided ample time for proper wound care at an earlier stage, some reliance can be placed on the quality and viability of tissue surrounding a completed vascular repair. If adequate soft tissue is not preserved to enable the repaired vessels to be covered then a superficial muscle such as the sartorius or gracilis may be freed with its blood supply intact and swung over to ensheath the repaired vessels. If that is not possible, then the skills of a plastic surgeon may have to be sought and free vascularized musculocutaneous flaps used to cover artery and vein repair and exposed bone. The construction of an extra-anatomic vein bypass through clean viable tissue may eliminate the need for these measures in some cases.

The adjunctive use of shunts in injured artery and vein limits the extent of ischaemia–reperfusion injury and its consequences, and reduces the necessity for fasciotomy.

Certain compartments are particularly vulnerable to short periods of raised compartment pressure; these include the muscle compartments of the forearm and hand in the upper limb, and the anterior compartment in the lower leg which lies within rigid osseous and fascial boundaries.

When shunts are used in managing complex vascular injuries the need for fasciotomy is reduced. There will of course be a percentage of patients who will require fasciotomy even when shunts have been used. If restoration of blood flow is delayed or fasciotomies are deemed necessary, then the procedure should be performed early as this will be beneficial to the residual collateral circulation. There may be occasions when this should be considered prior to the definitive vascular repair. If fasciotomy is delayed and tissue of tenuous viability (due to the ischaemia or trauma) is exposed, the chances of infection are high.

The clinician must repeatedly evaluate the need for fasciotomy before, during and after the vascular repair. Assessment should be based on clinical findings and, where necessary, compartment pressure monitoring.

Early haemorrhage after surgery usually arises from debrided tissues or from a gap in vascular repair. Thrombotic occlusion and secondary haemorrhage are the two most common complications of vascular repair (Box 12.9.5). The latter is likely to occur as a sequel to a scenario of insufficient vessel cover and infection within inadequately debrided tissue. An extra-anatomic vein graft should be considered in this situation.

Close monitoring of pulses, Doppler ultrasound pulse waveforms, and pressures will provide warning of deterioration in arterial flow. Vigilance is required in anticipating complete thrombotic occlusion of a vessel repair. If flow is impaired and graft failure is suspected, angiography must be undertaken urgently and the vascular repair revised. The defects which can be expected to lead to graft failure include constriction at the site of lateral suture, purse-string constriction of a direct anastomosis, inadequate excision of damaged vessel, anastomotic tension when the vein graft is too short, or slackness and kinking when it is too long. These last two problems are more likely to occur when vessel repair precedes bone fixation.

In isolated limb injuries, low-dose heparin may be of value in aiding graft patency and also in preventing DVT. It may be contraindicated in the multiply injured patient.

The challenge of combined vascular and orthopaedic injury must be faced in the knowledge that a number of complications including amputation may occur, but these can be minimized by prompt intervention. Diverse factors play a role in achieving good results, namely early recognition of arterial injury, if necessary defined by angiography, a methodical approach to operative technique, often best formulated around the use of indwelling shunts in both injured artery and vein, diligent care of the wound, stabilization of bone before vascular repair, liberal use of interposition vein grafts including compound vein grafts of suitable calibre when necessary, timely and effective fasciotomy, and a willingness to revise repair in the event of failure.