Fractures of the femoral shaft are one of the most common injuries treated by orthopedic surgeons. These fractures are often associated with polytrauma and can be life-threatening. They commonly result from high-energy mechanisms such as motor vehicle collisions (MVC) with sequelae of limb shortening and deformities if not treated appropriately. Femoral shaft fractures (FSF) typically occur in a bimodal distribution, high-energy trauma in the young population, and lower energy trauma in the elderly population. FSFs are also associated with other comorbidities necessitating a thorough advanced trauma life support (ATLS) assessment and interdisciplinary care. Intramedullary nailing (IMN) is the most common treatment for physiologically stable patients. The goal of fixation is early healing and long-term functional recovery. Treatment of modern-day femoral shaft fractures results in excellent outcomes. Anatomy Proximally, the femur is composed of a specialized metaphyseal region consisting of the head, neck, and greater and lesser trochanters. Distally, the femur comprises the metaphyseal flare, which continues into the medial and lateral femoral condyles, separated by the intercondylar notch. The shaft, or diaphysis, is the segment inferior to the lesser and ending at the metaphyseal flair and condyles. Classically the first 5 cm distal to the lesser trochanter is termed the subtrochanteric region and is considered a separate fracture pattern. These fractures are challenging to manage secondary to the muscular deforming forces. They will not be discussed in this article.[1] According to the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification of fractures, the femoral shaft begins at the inferior border of the lesser trochanter. It ends proximal to the condyles at a distance equal to the greatest width of the femoral condyles.[2]  The diaphysis is a smooth cylinder with differences in cortical thickness throughout its length, which may help assess intraoperative femoral rotation. The femur is bowed anteriorly with an average radius of curvature 120 cm (+/- 36 cm); the shorter the radius, the greater the bow.[3] The linea aspera is the major cortical thickening along the posterior aspect of the femur and is an attachment site for muscles and the medial and lateral intermuscular septa and acts as a compressive cortical strut.[4]  Three abundant muscular compartments envelop the femur. The anterior or extensor compartment is responsible for knee extension and houses the femoral nerve. The posterior or flexor compartment is responsible for knee flexion and houses the sciatic nerve. The medial compartment houses the adductor muscles. In FSF, the sciatic nerve and specifically the peroneal division are at the highest risk of injury because they lay close to the femoral shaft. The adductor compartment houses the obturator nerve. The gluteal muscles also surround and attach to the proximal femur and shaft; they include the gluteus maximus, medius, and minimus and cover the superior and inferior gluteal nerves. In FSF, the muscles are deforming forces on the fracture fragments depending on the location of the fracture. Generally, the proximal segment is flexed, abducted, and externally rotated by the iliopsoas and hip abductors. The distal segment is pulled proximally (shortened) by the quadriceps and hamstrings and adducted by the adductor muscles.  The main blood supply to the femur derives from the femoral artery, a continuation of the external iliac artery. The femoral artery passes under the mid-portion of the inguinal ligament and divides into the superficial femoral artery (SFA) and deep femoral artery (DFA), also known as the profunda femoris. The SFA supplies the tissues below the knee, and the DFA supplies the femoral shaft and the surrounding soft tissues. Multiple branches arise from the DFA, most notably the perforating arteries that encircle the femur. One or multiple nutrient arteries arise from the DFA or its branches to supply the inner 2/3 of the cortex and bone marrow. They anastomose with the metaphyseal-epiphyseal system. The periosteal blood supply supplies the outer one-third of the cortex.[5][6][7][8][9][4][10]