Shank vessel injuries: The forgotten vascular injuries

Historical perspective

During World War I, ligation of injured vessels below the knee was commonplace, and attempts at repair were rarely undertaken. This approach, however, led to an amputation rate above 70%. Similarly, data from World War II showed that the total incidence of vascular injuries among all casualties, including wounds of the extremities, was extremely small. However, the impact of these injuries is better appreciated when the frequency in which they appear as a cause of amputation is examined. De Bakey and Simeone looked at American data from the Mediterranean and European Theaters of Operations and reviewed 3177 major amputations from these theaters; of these 2179 (68.6%) were the direct result of extensive trauma, 380 (11.9%) were due to soft tissue infections particularly clostridial infections, and 618 (19.5%) were the result of major arterial injuries.

Data from a German amputation center showed that of 1359 major amputations, 64.3% were the result of trauma, very similar to the American incidence of 68.6%. Poor outcomes from World War II led surgeons to more aggressively pursue and repair these injuries during the later conflicts in both Korea and Vietnam. In a series reported by Rich consisting of 1000 major arterial injuries in Vietnam, the vast majority were repaired while only 15 arteries were ligated, compared with only 81 arterial repairs in 2471 arterial injuries in World War 11. Patients sustaining tibial vessel injuries from recent military conflicts in Iraq and Afghanistan have been reported to have an amputation rate ranging from 19% to 23%. The overall civilian amputation rate varies greatly depending on mechanism. Penetrating injury tends to have a lower amputation rate, but blunt injury with concomitant soft tissue defect and open fracture still have amputation rates of 40% to 50% ( Table 1 ).

Incidence and mechanism of injury

The actual incidence of shank vessel injury remains difficult to determine. Many injuries are likely missed since arteriography or CTA are not usually performed in the absence of physical signs and symptoms. There is a paucity of studies in the literature reporting on both the incidence and treatment of shank vessel injuries, when compared with other named vessels. Studies that do report these injuries report only a few cases. Overall, they are thought to comprise 5% or less of arterial injuries in the civilian population ( Table 2 ).

In a retrospective study by Ordog that reviewed 16,000 patients sustaining gunshot wounds (GSW), 755 had injuries below the knee; however, only 136/755 (18%) had a vascular injury evidenced by angiography. In another review by Grossman, only 20 of 100 patients with GSW below the knee sustained vessel injury. Some reviews have also included patients sustaining blunt trauma. One series by Keeley reported 17 vascular injuries from blunt trauma and 51 from penetrating, all GSWs. In a 12-year series by Padberg, there were 33 injuries from blunt trauma and 35 from GSW. In a more recent series by Haddock, >90% of these injuries requiring reconstructive surgery occurred from blunt trauma. During the current military conflicts, tibial vessel injuries account for 10% of vascular injuries. As seen by these multiyear reviews, the reported incidence of shank vessel injury is quite low, so clinical suspicion needs to remain high to establish the diagnosis ( Table 3 ).

Anatomy

Knowledge of the anatomy of the lower limb is of utmost importance in the evaluation and operative treatment of these vascular injuries. The popliteal artery courses behind the knee, where it bifurcates into the anterior tibial artery and the tibioperoneal trunk. The smaller of these two branches, the anterior tibial artery, arises near the distal portion of the popliteus and enters the interosseous membrane to provide the blood supply to the anterior compartment of the leg. After traversing roughly two thirds of this compartment, the anterior tibial artery travels anterior to the tibia and ankle joint, becoming the dorsalis pedis artery distal to the extensor retinaculum. This vessel can be palpated on the dorsum of the foot. Along with this vessel, two deep veins and the deep peroneal nerve follow in the same course.

The peroneal artery is the smallest of the three shank vessels. It passes laterally after branching from the tibioperoneal trunk and courses down toward the fibula. From here it continues in a fibrous sheath between the flexor hallucis longus and tibialis posterior muscles. Distally, the peroneal artery divides into the anterior and posterior calcaneal branches above the ankle; however, it does not communicate with the pedal arterial arch. This vessel is accompanied by two deep veins but it is not accompanied by a major nerve.

The popliteal artery continues on as the tibioperoneal trunk, which courses deep to the soleus muscle. The tibioperoneal trunk is variable in length, ranging from 2 to 5 cm, before it gives rise to the posterior tibial and peroneal arteries, the posterior tibial artery being a direct extension of the tibioperoneal trunk. The posterior tibial artery courses down over the tibialis posterior muscle and deep to both the soleus and gastrocnemius muscles. Distally, the artery lies over the flexor digitorum longus, then travels posterior to the medial malleolus where its pulse can be palpated. Subsequently it divides into the plantar arteries that supply the sole of the foot and its muscles. This vessel is also accompanied by two deep veins as well as the posterior tibial nerve.