A femoral neck fracture is a fracture of the femoral head inferior to the base of the femoral neck that is characterized by hip pain, pressure pain near the midpoint of the groin and longitudinal percussion pain.
Femoral neck fractures are a common injury in the elderly, but are also seen in middle-aged adults and children. Older patients are more likely to be female. The cause of the injury is mainly caused by twisting the injured limb when tripping and the violence is transmitted to the femoral neck, causing the fracture. The bones of the elderly are mostly osteoporotic, so it only takes a small amount of twisting violence to cause a fracture, and special attention must be paid to this.
Causes
There are two basic factors that cause fracture in the elderly, the internal bone strength decreases, mostly due to osteoporosis, the tension trabeculae in the femoral neck become thinner, the number decreases or even disappears, and finally the number of pressure trabeculae also decreases, coupled with the dense trophoid vascular pores in the upper femoral neck area, all of which can weaken the biomechanical structure of the femoral neck and make the femoral neck fragile; in addition, the periprosthetic muscles of the elderly degenerate and become unresponsive, which cannot effectively counteract the In addition, the periprosthetic muscle groups are degenerated and unresponsive, so they cannot effectively counteract the harmful stresses in the hip, plus the stresses on the hip are larger (2-6 times the weight) and the local stresses are complex and variable, so fractures can occur without much violence, such as slipping on a flat surface, falling off a bed, or sudden twisting of the lower limb, even without obvious trauma.
Clinical typing of femoral neck fracture
1. Rockwood (1984) divided femoral neck fractures into subcranial, transcranial and basal types, and added a cranial type according to the anatomical site of the fracture, which is divided into four types.
(1) Subtrochanteric type
The fracture line is completely under the femoral head, the entire femoral neck is distal to the fracture, and the femoral head is free to rotate within the acetabulum and joint capsule. This type of fracture is most common in elderly patients. The blood supply to the femoral head is severely damaged, and even if the round ligament artery exists, it can only supply blood to a small area of bone near the round ligament recess; and the round ligament artery gradually degenerates or even occludes with age. Therefore, these fractures are difficult to heal, and the incidence of ischemic necrosis of the femoral head is high, and the prognosis is poor.
(2) Head and neck type
This is an oblique fracture of the femoral neck. Since most of the femoral neck fractures are caused by torsional violence, true subtrochanteric and cervical fractures are rare, and most of the subtrochanteric fractures are associated with a femoral neck fracture block of different sizes, making the fracture line oblique. This type of fracture is difficult to reposition and has poor stability after repositioning, and the damage to the blood supply to the femoral head is second only to the subtrochanteric type.
(3) Trans-neck (mid-neck) type
The trans-neck fracture is often an artifact, and is often confirmed as a cephalocervical fracture on repeated radiographs.
(4) Basal type The fracture line is located at the base of the femoral neck. The fracture end has good blood flow, is easy to maintain stability after repositioning, and the fracture is easy to heal with good prognosis, so some scholars include it in the rotor fracture.
The fracture line of the first three types of fractures is located in the hip capsule, called intracapsular fracture; the fracture line of the basal type is located outside the capsule, called extracapsular fracture.
2.Typing by the direction of the fracture line.
(1) Abduction type: the lower limb is often in the abduction position during the fall. There is an abduction relationship between the two fractures, the pressure trabecular fracture is angled inward, the neck stem angle is increased, the bone ends are embedded, the position is stable, and the Pauwell angle of the fracture line is <30° or Linton <30°. This kind of fracture end shear force is small, the fracture is more stable, at the same time, due to the periprosthetic muscle tension and contraction force, prompting the fracture end to come together and apply certain pressure, which is conducive to fracture healing.
(2) Inclusion type: The lower extremity is often in the inversion position during the fall, the femoral head is inward, the fracture end is misaligned upward, the Pauwell angle of the fracture line is >50°, or the Linton angle of the fracture line is >50°, such fracture end is rarely embedded, the shear force between the fracture lines is large, the fracture is unstable, there is much displacement, the distal end rises due to muscle pull, and is externally rotated due to the weight of the lower extremity, and the blood flow of the joint capsule is more damaged. As a result, the healing rate is lower than the former and the necrosis rate of the femoral head is higher.
This classification often makes it difficult to determine the fracture line alignment due to the displacement and rotation of the femoral head.
3. There are four types of fracture according to the degree of fracture displacement (Garden’s typing method).
(1) Type I is an incomplete fracture.
(2) Type II is a complete fracture without displacement.
(3) Type III is a partially displaced fracture with abduction of the femoral head and mild external rotation and superior displacement of the femoral neck segment.
(4) Type IV is a completely displaced fracture with significant external rotation and upward displacement of the femoral neck segment.
Type I and II are stable fractures because the fracture ends are not displaced or are less displaced and the fracture damage is less; Type III and IV are unstable fractures because the fracture ends are more displaced and the fracture damage is greater.
Clinical manifestations.
1.Symptoms: elderly people who complain of hip pain after falling and are afraid to stand and walk should think of the possibility of femoral neck fracture.
2.Signs.
(1) Deformity: the affected limb has mild hip flexion and knee flexion and external rotation deformity.
(2) Pain: In addition to spontaneous pain in the hip, the pain is more obvious when moving the affected limb. Pain is also felt in the hip when the affected limb is tapped at the heel or the greater trochanter, and there is often pressure pain below the midpoint of the inguinal ligament.
(3) Swelling: Femoral neck fractures are mostly intracapsular fractures, with little bleeding after the fracture and surrounded by extra-articular plump muscles, therefore, local swelling is not easily seen in appearance.
(4) Dysfunction: Patients with displaced fractures are unable to sit up or stand after the injury, but there are some cases of nondisplaced linear fractures or insertion fractures that can still walk or ride a bicycle after the injury. Special attention should be paid to these patients. Do not turn a nondisplaced stable fracture into a displaced unstable fracture by missing the diagnosis. In displaced fractures, the distal end is displaced upward by muscle traction and thus the affected limb becomes shorter.
(5) Elevation of the greater trochanter on the affected side, as evidenced by.
(i) The greater trochanter is above the iliac-sciatic tuberosity joint (Nelaton line).
(2) The horizontal distance between the greater trochanter and the anterior superior iliac spine is shortened and shorter than that of the healthy side.
Examination.
Final confirmation requires a frontal and lateral x-ray of the hip, which is especially important for linear fractures or insertional fractures. It should be noted that some nondisplaced fractures may not be visible on the X-ray taken immediately after the injury, and CT and MRI examinations are feasible at that time, or the fracture line may not be clearly shown until 2-3 weeks later when some bone resorption occurs at the fracture site. Therefore, if a fracture of the femoral neck is clinically suspected, although the fracture line is not visible on the X-ray, the fracture should be treated as an insertional fracture and reviewed on film after 3 weeks. Another situation that is easily missed is multiple injuries, which often occur in young people at this time, due to some obvious injuries such as femoral stem fractures that conceal femoral neck fractures, so attention must be paid to hip examination for such patients.
Treatment principles.
There are two main problems in the clinical treatment of this disease: non-healing fracture (about 15%) and ischemic necrosis of the femoral head (20%~30%).
For its treatment, early non-invasive repositioning is mainly advocated. Following early non-invasive anatomical repositioning, choosing reasonable and effective internal fixation devices and methods, reducing local blood supply destruction, improving blood perfusion to promote early fracture healing, restoring and establishing blood vessels across the fracture line to rapidly participate in the repair of necrotic bone, and avoiding the occurrence of femoral head necrosis. Before choosing the treatment method, first of all, we should understand the general condition of the injured person, especially the elderly should pay attention to the comprehensive examination, heart, lung, liver, kidney and other major organ functions, combined with fracture comprehensive consideration. Femoral neck fractures are slow to heal, taking an average of 5-6 months, and the fracture non-healing rate is high, averaging about 15%. Factors affecting fracture healing are related to age, fracture site, fracture type, degree of fracture and displacement, quality of repositioning, and the strength of internal fixation.
Common clinical treatment modalities
1.Conservative treatment: Applicable to abductor and intermediate fractures, generally the affected limb is traction or anti-foot external rotation shoes for 8-12 weeks to prevent the affected limb from external rotation and internal rotation, which takes about 3-4 months to heal, and less often non-healing or femoral head necrosis occurs, but the fracture has the possibility of misalignment in the early stage, which generally takes about 4-6 months to heal, and the fracture should continue to be observed until five years after surgery to facilitate early detection of femoral head ischemia necrosis.
2.Internal fixation: Internal fixation has the widest indication, under the C-arm, closed reduction internal fixation, or open reduction internal fixation if no X-ray machine equipment is available. Before internal fixation, the fracture is repositioned manually to confirm the anatomical repositioning of the fracture end and then internal fixation is performed. There are many forms of internal fixation, but at present, hollow nail internal fixation is mainly used.
3.Bone grafting at the same time of internal fixation: For difficult healing or old fractures, bone grafting is used at the same time of internal fixation in order to promote healing.
① Free bone grafting: such as taking fibula or tibia and inserting it into the femoral head under the greater trochanter, or filling the bone defect with cancellous bone.
② Bone grafting with tip: the more commonly used is suturing muscle tip bone flap bone grafting. With the progress of microsurgery technology, bone grafting with vascular tip has been carried out. For example, bone grafting of deep iliac artery flap.
4.Artificial joint replacement
Indications.
1.Subcapital femoral neck fracture over 60 years old, Garden type III and type IV fracture.
2.Comminuted fracture of the subtrochanteric head and neck of the femur.
3, Aged >60 years old with old unhealed femoral neck fractures or patients who cannot tolerate the 2nd operation due to many coexisting conditions and poor general condition.
4.Patients with femoral neck fracture who cannot cooperate with the treatment, such as hemiplegic, Parkinson’s disease or psychiatric patients.
5.Adult idiopathic or traumatic ischemic necrosis of the femoral head is extensive, but the acetabular injury is not serious and cannot be repaired with other surgeries.
6.Benign tumor of the femoral neck that should not be scraped for bone grafting.
7, primary or metastatic malignant tumor of the femoral neck or pathological fracture, in order to reduce the patient’s pain, can be surgically replaced.
8, femoral head necrosis femoral head collapse, joint space narrowing, damaged acetabulum, clinical symptoms are obvious, conservative treatment is ineffective.