The femur is the longest and largest tubular bone in the human skeleton; the average length of an adult femur is 42.48 cm on the left side and 42.39 cm on the right side. The femur is cylindric in the upper third of its length, with the pectineal line running through the posteromedial surface of the femur, up to the base of the lesser trochanter. The pectineal line then continues with the intertrochanteric line, and down to the medial lip of the linea aspera. The gluteal tuberosity lies on the posterolateral aspect of the femur, up to the base of the greater trochanter and down to the lateral lip of the linea aspera. The middle part of the femur is slightly twisted and curved, with an anterior convexity that is 30 degrees rotated from the superolateral to inferomedial part of the femur. The lower third of the femur becomes flattened and widened anteroposteriorly. The linea aspera on the dorsal side of middle third has two lips that diverge and turn into the medial and lateral supracondylar ridge, respectively. The rough impression above the medial epicondyle gives origin to the medial head of the gastrocnemius, while the plantaris arises in the impression above and to the medial side of lateral epicondyle (▶ Fig. 4.1).
Based on the AO classification, the femoral fracture is coded as number “3.” According to “Heim’s Square,” the anatomic delineation of the proximal and distal shaft is by the numbers “31, 32, and 33,” respectively (▶ Fig. 4.2; ▶ Fig. 4.3).
A total of 193 patients with 196 femoral fractures were investigated in the China National Fracture Study (CNFS). The fractures accounted for 10.95% of all patients with fractures and 10.69% of all types of fractures. The population-weighted incidence rate of femoral fractures was 35 per 100,000 population in 2014.
The epidemiologic features of femoral fractures in the CNFS are as follows:
• More males than females
• More left-side injuries than right-side injuries
• The highest risk age group is 15–64 years
• The proximal femoral fracture is the most common femoral fracture
• Injuries occurred most commonly via slips, trips, or falls
Number of patients
Fig. 4.4 Sex distribution of 193 patients with femoral fractures in the China National Fracture Study (CNFS).
Number of patients
Fig. 4.5 Injury side distribution of 193 patients with femoral fractures in the China National Fracture Study (CNFS).
Fig. 4.6 (a) Age group distribution of 193 patients with femoral fractures in the China National Fracture Study (CNFS). (b) Age group and sex distribution of 193 patients with femoral fractures in the CNFS.
Fig. 4.7 Segment distribution of 193 patients with femoral fractures in the China National Fracture Study (CNFS) based on AO classification.
Fig. 4.8 Causal mechanisms distribution of 193 patients with femoral fractures in the China National Fracture Study (CNFS).
A total of 42,377 patients with 42,978 femoral fractures were treated in 83 hospitals of China over a 2-year period from 2010 to 2011. All cases were reviewed and statistically studied, accounting for 10.21% of all fractured patients and 9.95% of all types of fractures, respectively. Among these 42,377 patients, 3,243 are children with 3,282 fractures, and 39,134 adults with 39,696 fractures.
Epidemiologic features of femoral fractures are as follows:
• More males than females
• More left-side injuries than right-side injuries
• The highest-risk age group is 76–80 years. The most affected male age group is 41–45 years, while females aged 76–80 years have the highest risk.
• The proximal femoral fracture is the most common femoral fracture in adults. The diaphyseal femoral fracture is the most common femoral fracture in children.
Femoral Fractures by Sex
Number of patients
Number of patients
Fig. 4.11 (a) Age distribution of 42,377 patients with femoral fractures. (b) Age and sex distribution of 42,377 patients with femoral fractures.
Segment Distribution of Femoral Fractures in Adults Based on AO Classification
Number of fractures
Segment Distribution of Femoral Fractures in Children
Number of fractures
The head of the femur is globular in shape and forms about two-thirds of a sphere (▶ Fig. 4.14). The neck projects forward to some extent, with an average anterior projection of 10 to 15 degrees. Flattened posteriorly, the neck is contracted in the middle, which is often the site of fractures. In adults, the neck forms an angle of approximately 120 to 130 degrees with the body. At the junction of the neck with the upper part of the body, there is a large eminence called the greater trochanter. A smaller eminence projecting from the lower and posterior part of the base of the neck is called the lesser trochanter. Running obliquely downward and medial from the tubercle is the intertrochanteric line, while the intertrochanteric crest courses obliquely downward and medially from the summit of the greater trochanter on the posterior surface of the neck.
Based on AO classification, the proximal femur is coded as number “31.” It is further divided into three types: 31-A: Trochanteric fractures (extra-articular); 32-B: Femur neck fractures (articular); 33-C: Femur head fractures (intra-articular) (▶ Fig. 4.15).
A total of 28,027 proximal femur fractures were treated in 83 hospitals of China over a 2-year period from 2010 to 2011. All cases were reviewed and statistically studied; the fractures accounted for 70.60% of femur fractures in adults. Their epidemiologic features are as follows:
• The highest-risk age group for both sexes is 76–80 years
• The most common fracture type among segment 31 fractures is type 31-B. However, 31-A is more common in males while 31-B is more common in females
• The most common fracture group among segment 31 fractures is group 31-A2, the same fracture group in both males and females
Fractures of Segment 31 by Sex
Number of fractures
Fig. 4.17 (a) Age distribution of 28,027 fractures of segment 31. (b) Age and sex distribution of 28,027 fractures of segment 31.
Fig. 4.18 (a) Fracture type distribution of 28,027 fractures of segment 31. (b) Sex and fracture type distribution of 28,027 fractures of segment 31.
Fig. 4.19 (a) Fracture group distribution of 28,027 fractures of segment 31. (b) Sex and fracture group distribution of 28,027 fractures of segment 31.
31-A1 Pertrochanteric simple
M: 1,719 (51.65%)
F: 1,609 (48.35%)
0.89% of total adult fractures
8.38% of adult femoral fractures
11.87% of segment 31
26.12% of type 31-A
31-A1.1 Along the intertrochanteric line
31-A1.2 Through the greater trochanter
31-A1.3 Below the lesser trochanter
M: 3,542 (47.81%)
F: 3,866 (52.19%)
1.98% of total adult fractures
18.66% of adult femoral fractures
26.43% of segment 31
58.13% of type 31-A
31-A2.1 With one intermediate fragment
31-A2.2 With several intermediate fragments
31-A2.3 Extending more than 1 cm below the lesser trochanter
M: 1,219 (60.74%)
F: 788 (39.26%)
0.54% of total adult fractures
5.06% of adult femoral fractures
7.16% of segment 31
15.75% of type 31-A
31-A3.1 Simple oblique
31-A3.2 Simple transverse
31-A3.3 Multifragmentary, fracture line extending into the diaphysis
31-B1 Subcapital, with slight or no displacement
M: 1,234 (41.90%)
F: 1,711 (58.10%)
0.79% of total adult fractures
7.42% of adult femoral fractures
10.51% of segment 31
21.79% of type 31-B
31-B1.1 Impacted with valgus displacement ≥ 15 degrees
31-B1.2 Impacted with valgus displacement ≤ 15 degrees
M: 3,070 (44.69%)
F: 3,800 (55.31%)
1.83% of total adult fractures
17.31% of adult femoral fractures
24.51% of segment 31
50.83% of type 31-B
31-B2.2 Midcervical adduction
31-B2.3 Cervical shear
M: 1,331 (35.96%)
F: 2,370 (64.04%)
0.99% of total adult fractures
9.32% of adult femoral fractures
13.21% of segment 31
27.38% of type 31-B
31-B3.1 Moderate displacement in varus and external rotation
31-B3.2 Moderate displacement in vertical translation and external rotation
31-B3.3 Marked displacement in varus or vertical translation
M: 493 (61.47%)
F: 309 (38.53%)
0.21% of total adult fractures
2.02% of adult femoral fractures
2.86% of segment 31
45.36% of type 31-C
31-C1.1 Avulsion of the round ligament
31-C1.2 Fracture with rupture of the round ligament
31-C1.3 With a large fragment
M: 348 (56.40%)
F: 269 (43.60%)
0.16% of total adult fractures
1.55% of adult femoral fractures
2.20% of segment 31
34.90% of type 31-C
31-C2.1 Posterior and superior
31-C2.2 Anterior and superior
31-C2.3 Split and compressed
M: 198 (56.73%)
F: 151 (43.27%)
0.09% of total adult fractures
0.88% of adult femoral fractures
1.25% of segment 31
19.74% of type 31-C
31-C3.1 Head split and neck fractured in transcervical region
31-C3.2 Head split and neck fractured in subcapital region
31-C3.3 Head compressed and neck fractured
Intertrochanteric fracture can be caused by a direct force applied perpendicularly to the trochanteric area, or an indirect varus force transmitted to the intertrochanteric area through the hip. The forceful contraction of the gluteus medius and gluteus minimus muscles, or having the lower limb in hyperadduction, may lead to an avulsion fracture of the greater trochanter, while the pull of the iliopsoas muscle may result in avulsion of the lesser trochanter. Intertrochanteric fractures often occur in the elderly, mostly caused by falls. Since elderly patients often have osteoporotic bones, the resulting fractures are frequently complex fractures.
Femoral neck fractures can be caused by two types of force. Fractures may result from violent rotation of the hip as a result of falling onto the lateral aspect of the hip. This type of injury can also be caused by an indirect force transmitted to the neck through the greater trochanter, as seen in falls onto one’s side from a height or a standing position. With decreased muscle tone in the hip area and increased bone fragility resulting from osteoporosis, elderly patients can sustain femoral neck fractures from minimal forces like a fall from a bed, sudden movements, or twisting of the leg. In young people, fractures of the femoral neck occur more frequently from high-energy trauma like car accidents or falls from a significant height. Avascular necrosis of the femoral head often occurs as a result of vascular disruption after fracture of the femoral neck.
Femoral head fractures usually result from a major force to a flexed knee and hip; the resulting force transmits to the hip joint through the axis of the femur and often leads to a posterior dislocation of the hip joint. When the fracture occurs with the hip flexed, abducted, and externally rotated, an anterior dislocation of hip joint usually follows.
If there is minimal or no displacement, patients may present with pain on palpation and percussive pain along the axis of the femur. If there is marked displacement, a typical presentation may include pain, deformity, abnormal range of movement, bony crepitus, and shortening of the involved limb. Imaging examinations must include standard anteroposterior (AP) and lateral views of the fracture site. A comparison AP view of the pelvis with the uninjured side is helpful in detecting fracture displacement, if the displacement is minimal. Computed tomography (CT) scanning might be indicated. For subtrochanteric fractures, radiographs should be taken to include the whole length of the diaphysis to rule out diaphyseal fractures of the femur.
Femoral Neck Fracture
Femoral neck fractures are intracapsular; therefore, patients may not present with much swelling. Physical examination reveals local pain to palpation and percussive pain along the axis of the femur. A standard hip radiographic series, including AP and lateral views of the affected hip, or a comparison AP view of the pelvis with the unaffected side, should be considered if neck fracture is suspected. Measurement of the Pauwel angle will be helpful in assessing the degree of fracture stability. If indicated, a CT scan of the hip joint should be carried out, which should include views of the acetabulum, the neck of femur, the head of femur, and the greater and lesser trochanter. A thin-slice CT scan and 2D- or 3D-CT reconstruction may also be required. CT is exquisitely useful for imaging abnormalities of the bone itself, such as in the disruption of the cortical bone and trabecula, and especially in detecting incomplete fractures without trabecula displacement. CT is the most useful test for evaluating bony injury, assessing the type of fracture and the degree of the displacement, and detecting the number and the location of the fragments.
The Garden classification is the most commonly used standard to assess the severity of femoral neck fracture in clinical setting. The Garden type I femoral neck fractures are defined as incomplete fractures of the neck of the femur as seen on the AP radiograph of the injured hip. In a prospective study, Zhang et al confirmed that incomplete femoral neck fractures identified on X-ray films are actually complete fractures on CT.
Femoral Head Fractures
The clinical presentation of femoral head fractures is atypical if the fractures are not displaced. Patients with femoral neck fractures usually present with different levels of pain to palpation over the hip joint, and percussive pain along the axis of femur. If the fractures are displaced, physical examination reveals bony crepitus, or a limited range of movement of the hip joint. Imaging examinations should include AP and lateral views of the hip joint and an AP view of the pelvis. A CT scan should be considered if X-ray films are equivocal. CT scans are not only useful in diagnosing but can also provide guidance on treatment. Plain radiographic findings on pediatric slipped capital femoral epiphysis and traumatic femoral head epiphysiolysis include a widening of the epiphyseal line, widening and irregularity of the growth plate, separation and displacement of the epiphyseal line from the metaphyses, and inferomedial displacement of the epiphysis. CT and magnetic resonance imaging (MRI) should be considered under such circumstances. Femoral head fractures in adults are more commonly fractures of the apex of the femoral head, and the resulting fragments often lie within the capsule. Radiographic images reveal the femoral head defect or irregularity. If there is fracture displacement, the fracture of the superior rim of the acetabulum usually accompanies the fracture. If the X-ray film cannot point to a clear diagnosis of a femoral head fracture, MRI is required to further to assess the nature of the fracture, or the location and the course of the fracture line. When fractures involve subchondral bones, MRI can clearly reveal the extent of the fracture.
Intramedullary nails, like the Gamma nail and proximal femoral nail (PFN), are usually used for internal fixation of proximal femoral fractures. Intramedullary nails have the biomechanic properties of internal fixators, and offer the advantage of small incisions and short operation times. Gamma nail fixation requires the affected limb to be slightly adducted, and traction for anatomic reduction. Radiographic measurement of femoral canal diameters and the shape of the femoral diaphysis must be done before the surgery. PFNs should not be used in patients with marked anterior bowing of the femur. Other internal fixators often used for fixation of proximal femoral fractures include dynamic hip screw (DHS), dynamic condylar screw (DCS), and DHS trochanter stabilizing plates, which provide double fixation by performing compression and a sliding motion leading to dynamic compression at the fracture site.
Femoral Neck Fractures
Subcapital fractures of the femoral neck have a high incidence of avascular necrosis of the femoral head. In young patients with good preservation of bone stock, one should consider artificial femoral head replacement or biological fixation of a total hip prosthesis. For elderly patients with osteoporotic bones, a self-centering bipolar head or total hip replacement is recommended. Transcervical femoral neck fractures can be fixed by screws, usually by three cancellous screws, which offer the advantages of providing significant compression to the fracture site, avoiding rotation, and causing minimal bone damage. The Anchor nail, developed by a group of talented orthopaedic surgeons at our hospital, combines the beauty of the Trifin nail and compression screw, which has the advantages of providing compression and anti-rotation at the fracture site with a simple procedure. A good clinical outcome has been observed after its application in treating femoral neck fractures in our hospital. Basicervical fractures can be treated surgically or conservatively, depending on the patient’s medical condition. If complex basicervical fractures occur in patients with osteoporotic bones or with multifragmentary fractures of the cortical bone, then management should involve DHS and angle plates. A screw can be added to the DHS proximally to restore the rotational stability of the bone and provide support and fixation.
Anatomical reduction is difficult to achieve in some femoral neck fractures with routine manipulative maneuvers, and they require open surgical intervention. This kind of irreducible femoral neck fractures is frequently complicated by avascular necrosis of the femoral head and nonunion of the fracture. Three-dimensional interreaction reduction was invented by Zhang et al to deal with those problems. Zhang et al designed a quantitative score system used in treatment of adult femoral neck fractures with high factors for nonunion (age > 50 years, females, displacement fracture, high energy injury, and American Society of Anesthesiologists (ASA) grade above III), which includes patient’s age, fracture type, bone mineral density, activities of daily living, and medical comorbidities. This quantitative score system helps in surgical decision-making regarding the treatment choice for adult patients with femoral neck fractures. In order to prevent nonunion and femoral head necrosis of femoral neck fracture, adult fresh femoral neck fractures with high factors for nonunion require early intervention, which consists of free iliac bone graft transplanting with bilateral cortical bone and internal fixation.
Femoral Head Fractures
If the fracture occurs in a nonweight-bearing part of the femur, with small free-floating fragments sitting within the joint capsule, then the floating fragments should be taken out to avoid further damage to the joint. If the fracture occurs in a weight-bearing section of the femur, small lag screws or absorbable screws can be inserted from the nonweight-bearing section to fix the fracture, with the head of the nail just beneath subchondral bone. As more than two-thirds of femoral head fractures involve a split head with an associated neck fracture or acetabular fracture, a total hip replacement is usually the treatment of choice.
Femoral shaft fractures occur in the region extending from the lesser trochanter to the flare of femoral condyles (▶ Fig. 4.20). The body of the femur, almost cylindrical in form, is a little broader superiorly than in the center, and somewhat flattened and widened anteroposteriorly, especially at the lower end. It is slightly curved with a smooth convexity anteriorly, and strengthened posteriorly by a prominent longitudinal ridge, the linea aspera, which continues into the gluteal tuberosity super-olaterally. The diameter of the femoral shaft and the thickness of the cortical layer of the shaft are associated with the weight bearing and the tension applied to the femur. As a result, the cortical layer of the shaft attenuates toward the proximal and distal ends of the femur.
Based on AO classification, the diaphysis of the femur is coded as number “32.” It is further divided into three types depending on fracture patterns: 32-A: Simple fracture; 32-B: Wedge fracture; and 32-C: Complex fracture (▶ Fig. 4.21).