Popliteal vessel injuries: Complex anatomy and high amputation rates

Historical perspective

In 1906, José Goyanes from Spain first resected a traumatic popliteal artery aneurysm and used the adjacent popliteal vein to reconstruct the popliteal artery with an interposition graft. He is thus credited with the description of the first autogenous reverse saphenous vein graft.

Any further discussion of popliteal vessel injuries should commence by reviewing the knowledge acquired in the management of battlefield injuries. These lessons have proved to be invaluable in the management of these injuries: the overwhelming majority of battlefield injuries involve the lower and upper extremities. These injuries are the consequence of high-velocity missiles, shrapnel, and fragments as well as antipersonnel devices causing considerable soft tissue loss, complex bony fractures, and nerve injuries.

Any time delay between the battlefield and immediate surgical care is always detrimental. At the end of World War II, the time lost with evacuation and surgical preparation was not improved until the surgical support could be moved forward to the front lines of future conflicts. Introducing surgical teams to the battlefield proved to be a valuable lesson with each conflict. However, vascular injuries in the lower extremity were met with higher complications than the upper extremity in early wartime history. In the World War I British experience, Makins observed a 12% incidence of popliteal injuries with an amputation rate of 43%. During World War II, DeBakey and Simeone’s review demonstrated 502 popliteal artery injuries, accounting for an overall incidence of 20%. Of those patients, 499 required ligation resulting in an amputation rate of 72.5%. When comparing both world wars, the higher rates of amputation may correspond to the change in weaponry, notable tissue destruction, disrupted collateral circulation, and ligation as a primary surgical intervention as opposed to repair.

During the Korean War, Hughes reported 79 popliteal artery injury repairs, of which 32.4% required amputations. Approximately 600 popliteal vessel injuries were recorded in the Vietnam Vascular Registry, including identification of 300 popliteal artery injuries for an overall incidence of 18.3%. Rich evaluated 150 of these patients who completed comprehensive follow-up and found that 58.7% had concomitant venous injuries. In addition, the researchers identified 110 patients with popliteal venous trauma without any associated arterial trauma. Ligation of the injured vein was also an acceptable practice in the management of early wartime vascular trauma; however, it was during the Korean War that popliteal vessel repair demonstrated a reduction in the amputation rates compared with ligation, a common practice in both world wars. When vascular repair was performed during Vietnam and Korean conflicts, amputation rates dropped significantly to 32% and 33%, respectively. These prior wartime endeavors markedly contributed to the advanced practices in vascular trauma for the modern conflicts of the 21st century.

In Woodward’s analysis of the Balad Vascular Registry database, 9289 battle-related casualties were identified over a 32-month period. Of these, 488 patients were diagnosed with 513 vascular injuries including 45 popliteal vessel injuries. Popliteal artery injury alone accounted for 35.6%, and 62.2% represented combined popliteal venous and arterial injury. Modern wartime trauma presents with other mechanisms of injury compared with previous historical conflicts. The reintroduction and use of improvised explosive devices by Iraqi insurgents accounted for 27 popliteal injuries, and high-velocity gunshot wounds accounted for 18 additional injuries. Regardless of the wounding mechanism, considerable soft tissue loss and orthopedic injury are common components of these traumas, therefore mandating multiple surgical interventions and a multidisciplinary approach.

Unfortunately, the prevalence of vascular injury in Iraq was twice that of Vietnam. Popliteal artery injury accounts for 8.6% of vascular injuries with an early amputation rate of 14.3% in survivors. In a retrospective study by Fox, 8618 casualties were admitted to a combat support hospital in Baghdad. All injuries were sustained from gunshot wounds or high-energy explosives. Among those wounded, 48 popliteal artery injuries were identified with 37% combined venous and arterial injury. Various surgical therapies were used, including autogenous reversed saphenous vein graft (69%), vein patch (2%), lateral arteriorrhaphy (19%), and end-to-end anastomosis (2%). Any concomitant venous injury identified required management by ligation, repair, or graft. The overall limb salvage failures accounted for 29%; however, complications rates remain high.

Historical outcomes proved high rates of amputations with vessel ligation in vascular trauma. Remarkable improvements, however, were later appreciated with surgical repair. Successful modern wartime vascular surgery evolved from these historical conflicts by reductions in evacuation times, improved resuscitation efforts, and the evolving surgical management practices. Changes in evacuation and development of neighboring surgical care drastically reduced ischemic delays and, when combined with aggressive damage control resuscitation initiatives, contemporary wartime vascular injuries have resulted in higher rates of battle casualty survival and improved limb salvage ( Table 1 ).

Anatomy

The popliteal artery arises from the superficial femoral artery as it travels through the adductor canal, which is enclosed by the sartorius muscle and covered by the semimembranosus and semitendinosus muscles. As it continues coursing posteriorly in the popliteal fossa, the artery and vein, as well as the tibial nerve, become sheltered by superficial subcutaneous tissue. The popliteal artery and vein are positioned anatomically between the medial and lateral heads of the gastrocnemius and popliteus muscle. The floor of the popliteal fossa is formed by the knee joint’s capsule, popliteal surface of the femur, and the fascia of the popliteus muscle. It is in this location that the popliteal artery becomes most susceptible to trauma secondary to skeletal injury, such as fractures or dislocations. At this level, a complete collateral network supplied by the popliteal artery gives rise to the geniculate, sural, and muscular branches to join both the profunda femoris proximally and the tibial arteries distally. It is above the knee joint that the popliteal artery gives rise to the superior lateral and superior medial genicular arteries and below the knee are the inferior lateral and inferior medial genicular arteries. The terminating branch of the popliteal artery begins at the level of its bifurcating branches, the tibioperoneal trunk and the anterior tibial artery.

Understanding the “traditional” popliteal anatomic description is as important as recognizing that the vascular framework of the adult popliteal artery and vein remains variable regarding the length and branching patterns. The most common terminal branch arrangement of the popliteal artery is the anterior and posterior tibial arteries. This is classically found several centimeters distal to the femoral condyle, followed by a more distal fibular artery arising from the posterior tibial artery. This “normal” popliteal artery pattern has been described as occurring in 92.8% by Bardsley and Staple, with similar findings appreciated in other investigative publications. Complex variability in popliteal venous anatomy is well demonstrated by lower limb dissections as reported by Cross, illustrating distinctive components of interconnecting veins. These anatomic descriptions portray appreciable vessel variation within the popliteal fossa and therefore justify the importance of surgical repair whenever feasible.

Incidence

In busy urban trauma centers, management of civilian popliteal vessel injuries remains a daunting task. The majority part of surgical literature consists of institutional retrospective data review; furthermore, traumatic mechanisms and characteristic injuries are fittingly investigated. Mullenix’s analysis of 1,130,000 patients from the National Trauma Data Bank (NTDB) identified 1395 popliteal injuries for an incidence of less than 0.2%. In Kauvar’s NTDB review, 651 isolated infrainguinal arterial injuries were identified, the popliteal artery being the most common injured vessel at 35.5%. In South Africa, comparable results reveal a 30.7% incidence reported in the international literature ( Table 2 ).

Lower extremity arterial injury overwhelmingly results from penetrating trauma in high-volume Level I trauma centers. In Fabian’s series consisting of 165 popliteal artery injuries, 125 patients’ injuries resulted from penetrating trauma. Other trauma centers may observe injuries predominantly associated with blunt mechanism. Harrell evaluated 38 popliteal artery injuries, all the direct consequence of blunt mechanisms. On closer evaluation of 24 series by Frykberg, penetrating popliteal artery injury accounted for 56% of the cases. Universally, blunt injury to the popliteal artery varies from 20% to 84% in various urban trauma centers.

Hafez’s 10-year review examined 641 lower extremity injuries, of which 30.7% were popliteal arterial injuries. The highest rates of limb loss, approximately 25%, were appreciated in above-knee popliteal artery injuries. Stab injuries were less likely to be associated with amputation. The overall contributing factors to limb loss include nerve injury and compound fractures. The most common associated injury was venous, specifically venous segmental branches. Several review series report an incidence of associated venous injury up to 34%. Franz found a 25% incidence of associated venous injuries with popliteal arterial injuries, and Jaggers found that 28% of his patients had combined arteriovenous injuries.

Older series exhibited higher rates of amputation than the last several decades. Limb-threatening vascular injuries can be associated with high-energy blunt mechanisms with resulting knee dislocation and complex orthopedic injury as well as high-velocity gunshot wounds. The incidence of civilian amputation rates from popliteal vessel injury range from 6% to 37%. In selected series various mechanisms of blunt crush injury have seen amputation rates as high as 52.5%.

Managing limb ischemia represents the highest priority with the most important goal being immediate restoration of circulation. Patterson reported on 18 patients from the Lower Extremity Assessment Project study, a multicenter, prospective longitudinal study. All were due to blunt mechanical forces with associated knee dislocations and popliteal artery injury. Sixteen lower extremities had at least a popliteal injury repair, and at final follow-up, 14 knees were successfully salvaged but 4 required amputation. On further review, knee dislocation and associated vascular injury in high-volume trauma centers may result in amputation rates as high as 52%.

Adult traumatic vascular injury constitutes the majority of published reviews, leaving minimal emphasis on pediatric vascular trauma. Most pediatric vascular injuries are due to iatrogenic causes. However, sporadic documented cases and series review articles of penetrating and blunt popliteal injury exist and are still exceptionally rare. Corneille’s retrospective review identified 116 pediatric trauma patients sustaining 138 vascular injuries over a 13-year period. In these series, there were 29 patients with lower extremity injuries with a total of 36 vessels injured. The popliteal vein was the most commonly injured vein. The popliteal artery, however, only accounted for 19% of the injuries in comparison with 30.6% of all vessels injured below the knee. Regardless, noniatrogenic vascular injury in the pediatric population is rare, and when popliteal vessel injuries present themselves, limb salvage rates are exceptional high with early identification and surgical treatment.