Lower extremity injuries most frequently involve the lower leg and ankle, followed by the foot and toes, hip, and then knee.1
The thigh contains two fascial layers; the superficial fascia containing fat, lymphatics, cutaneous nerves, and superficial veins; and the deep fascia, containing muscles, major vessels, and nerves.
Thigh lacerations typically involve skin and superficial fascia, although deep lacerations can penetrate the deep fascia and into the underlying muscle. Lacerations in the area of the femoral triangle can injure the femoral nerve, artery, or vein (Figure 44-1A). Arterial injury resulting from penetrating and blast wounds most commonly affects the femoral artery or its branches: circumflex, deep femoral, popliteal, and geniculate (Figure 44-1B). Vascular injury is the most life- and limb-threatening concern, with arterial injuries at high risk for limb loss.2 Suprapatellar lacerations may involve the quadriceps tendon, resulting in impaired knee extension. Compartment syndrome is a rare complication of thigh wounds (see Chapter 278, “Compartment Syndromes”).
Thigh anatomy. A. Nerves, arteries, and veins in the femoral triangle. B. Femoral artery and its branches. a = artery; m = muscle. [Reproduced with permission from Morton DA, Foreman KB, Albertine KH: The Big Picture: Gross Anatomy, McGraw-Hill Education, Inc. © 2011, Figure 36-4.]
The muscles of the lower leg are organized into four fascial compartments (see Figure 278-1). Muscles in the anterior compartment primarily produce extension (dorsiflexion) and inversion (Figure 44-2A); muscles in the superficial and deep posterior compartments primarily produce flexion (plantarflexion) and inversion (Figure 44-2B); and muscles in the lateral compartment primarily produce flexion (plantarflexion) and eversion (Figure 44-2C).
Muscles of the lower leg. A. Anterior compartment. B. Superficial posterior compartment. C. Lateral compartment. m = muscle; mm = muscles. [Reproduced with permission from Morton DA, Foreman KB, Albertine KH: The Big Picture: Gross Anatomy, McGraw-Hill Education, Inc. © 2011, Figures 37-1C, 37-3A, and 37-2, respectively.]
Several important tendons in the lower leg are at risk for injury. The fibularis longus and fibularis brevis (also known as the peroneus longus and peroneus brevis) tendons, which contribute to foot plantar flexion and eversion, run behind the lateral malleolus and can be lacerated at this location (Figure 44-2C). Lacerations of the shin rarely involve vital nerves or tendons, but infrapatellar lacerations can transect the patellar tendon, resulting in inability to extend the leg. The common peroneal nerve can be injured in complex fractures, sharp injuries, or lacerations of the lower extremity, resulting in foot drop (Figure 44-3).3