Symptom >> Surgical >> Orthopedics

Hip flexion and external rotation deformity

Introduction
Cause
Examine
Diagnosis

Introduction

Introduction Patients with femoral neck fractures have mild hip flexion and external rotation deformity. Femoral neck fractures often occur in the elderly. As people's life span increases, their incidence is increasing, with 50-70 years old being the most. There are two basic factors that cause fractures in the elderly. The internal bone strength decreases, mostly due to osteoporosis. The double-quantum densitometer confirms that the femoral neck tension trabecular bone becomes thinner, the number decreases or even disappears, and finally the number of pressure trabecular bones decreases. In addition, the upper part of the femoral neck nourished the vascular pores (according to 200 adult femoral neck area measurements measured an average of 14.6 ± 0.22 standard deviation of 3.1), can weaken the femoral neck biomechanical structure, making the femoral neck fragile.

Cause

Cause

(1) Causes of the disease

There are two basic factors that cause fractures in the elderly. The internal bone strength decreases, mostly due to osteoporosis. The double-quantum densitometer confirms that the femoral neck tension trabecular bone becomes thinner, the number decreases or even disappears, and finally the number of pressure trabecular bones decreases. In addition, the upper part of the femoral neck nourished the vascular pores (according to 200 adult femoral neck area measurements measured an average of 14.6 ± 0.22 standard deviation of 3.1), can weaken the femoral neck biomechanical structure, making the femoral neck fragile. In addition, due to the degeneration of the hip muscles in the elderly, the response is slow, can not effectively offset the harmful stress of the hip, plus the hip is subjected to greater stress (weight 2 to 6 times), the local stress is complex and variable, so it does not need much Violence, such as slipping on the ground, falling from the bed, or sudden torsion of the lower limbs, can even occur without obvious trauma. The young and middle-aged femoral neck fractures are often caused by serious injuries such as car accidents or high-altitude falls. Occasionally, due to excessively long-term heavy-duty labor or walking, gradually fractures are called fatigue fractures. The femoral neck fractures in young adults are often caused by serious injuries. In addition, the blood supply of the femoral head is also one of the causes of fracture nonunion and femoral head necrosis.

(two) pathogenesis

Femoral neck fractures occur mostly in the elderly, and the incidence of women is higher than that of men. Because the elderly have different degrees of osteoporosis, and female activities are relatively less than men, osteoporosis occurs earlier due to physiological metabolism, so even if the injury is not heavy, fractures will occur. Atkin (1984) 84% of patients with femoral neck fractures had varying degrees of osteoporosis. When Barth et al. performed artificial joint replacement for patients with femoral neck fractures, the medial femoral cortex was removed for histological observation. Compared with the control group. It was found that the bone unit was significantly reduced and the Harvard tube was widened. Frangakis studied the relationship between femoral neck fractures and osteoporosis in older women, suggesting that 50% of bone-minerals in 65-year-old women are below the fracture threshold. In 85-year-old women, 100% of bone minerals are below the fracture threshold. It is generally believed that although it is not the only factor, osteoporosis is an important factor in the fracture of the femoral neck. Some scholars believe that the femoral neck fracture of the elderly can be regarded as a pathological fracture. The degree of osteoporosis has a direct impact on the comminution of the fracture (especially the posterolateral femoral neck comminution) and the firmness of the internal fixation.

Most elderly patients with femoral neck fractures have minor trauma, and young femoral neck fractures are mostly caused by severe trauma. Kocher believes that the damage mechanism can be divided into two types: 1 The large trochanter is directly impacted when falling. 2 limbs external rotation. In the second mechanism, the femoral head is relatively fixed due to the anterior joint capsule and the patellofemoral ligament, the femoral head rotates backward, and the posterior cortex hits the acetabulum and causes a neck fracture. In this case, complication of the posterolateral cortical bone often occurs. The violence caused by femoral neck fractures in young people is much greater. The violent extension of the femoral shaft is directly transmitted upwards, often accompanied by soft tissue injury, and fractures often occur.

Examine

an examination

Related inspection

CT examination of bone and joint and soft tissue

[clinical manifestations]

Symptom

Older people complain of hip pain after falling, do not dare to stand and walk, should think of the possibility of femoral neck fracture.

2. Signs

(1) Malformation: The affected limbs have mild hip 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. When the affected limb is heeled or the large trochanter is beaten, the hip is also painful, and there is often tenderness below the midpoint of the inguinal ligament.

(3) Swelling: There are many intracapsular fractures of the femoral neck fracture. There is not much bleeding after the fracture, and there is a thick muscle group surrounded by the joints. Therefore, the swelling is not easy to see in the appearance.

(4) Dysfunction: Patients with displaced fractures cannot sit or stand after injury, but there are also cases of non-displaced linear fractures or inset fractures, which can still walk or ride bicycles after injury. Pay special attention to these patients. Do not miss the diagnosis of a dislocation-stable fracture into a displaced unstable fracture due to missing diagnosis. The affected limb is shortened, and the fracture is displaced. The distal end is pulled by the muscle group and displaced upward, so that the affected limb becomes shorter.

(5) The ipsilateral large trochanter is elevated, which is manifested in: 1 horizontal trochanter above the iliac-ischial nodule line (Nelaton line), the horizontal distance between the 2 large trochanter and the anterior superior iliac spine is shortened, shorter than Jian side.

There are many classification methods for femoral neck fractures, which can be divided into three categories: 1 According to the anatomy of the fracture. 2 The direction of the fracture line. 3 degree of fracture displacement.

1 According to the anatomical part classification: Many authors have divided the femoral neck fracture into 3 types according to the anatomy of the fracture: sub-head type, trans-cervical type and basal type. The subcephalic and transcervical types belong to intracapsular fractures, while the basal type belongs to extracapsular fractures. The subcephalic type refers to a fracture located in the middle of the femoral neck, and the basal type refers to a fracture located between the base of the femoral neck and the trochanter. Klenerman, Garden et al. believe that it is difficult to distinguish between the under-head type and the neck-type type on the X-ray film due to different projection angles. Klenerman, Marcuson, and Banks all believe that simple cervical fractures are extremely rare. Because the incidence of cervical fractures is very low, the X-ray performance of various types is greatly affected by the angle of projection. At present, such classification has been rarely applied.

2 According to the fracture line direction classification (Pauwels classification): In 1935, Pauwels divided the femoral neck fracture into 3 types according to the direction of the femoral neck fracture line (Fig. 2): the angle between the type I fracture line and the horizontal line was 30°; The angle between the fracture line and the horizontal line is 50°; the angle between the type III fracture line and the horizontal line is 70°. Pauwels believes that the larger the angle, the more vertical the fracture line, the shear stress at the fracture end, the more unstable the fracture, and the non-healing rate increases. There are two problems with this classification. First, the femoral neck and the X-ray film must be parallel when the X-ray film is projected, which is difficult to achieve clinically. Due to pain and other reasons, the patient often tilts the pelvis when taking X-ray films, and the direction of the fracture line changes. The same femoral neck fracture, due to the degree of pelvic tilt, can show different results from Pauwels type I to Pauwels type III on X-ray films. Second, there is no significant correlation between Pauwels classification and nonunion of femoral neck fracture and avascular necrosis of the femoral head. Boyd, George, Salvatore et al found that in 140 patients with Pauwels type I, the rate of nonunion was 0, and the rate of avascular necrosis of the femoral head was 13%. In 295 patients with Pauwels type II, the rate of nonunion was 12% and the rate of avascular necrosis of the femoral head was 33%. In 92 patients with Pauwels type III, the rate of nonunion was only 8%, and the rate of avascular necrosis of the femoral head was 30%. Because Pauwels classification is greatly affected by X-ray projection, it has no corresponding relationship with fracture nonunion rate and avascular necrosis rate of femoral head.

3 fracture degree classification (Garden classification): Garden divided the femoral neck fracture into 4 types according to the degree of fracture displacement (1961) (Fig. 3). Type I incomplete fracture, complete trabecular bone under the femoral neck, this type includes so-called "abduction inlay fracture; type II complete fracture, but no displacement; type III complete fracture, partial displacement, this type of fracture on the X-ray film It can be seen that the distal end of the fracture is moved up and down, the femoral head is often tilted backward, and there is partial contact at the fracture end; the type IV complete fracture is completely displaced. The fracture on the X-ray film shows that the fracture end is completely contactless. The relative relationship between the bone and the acetabulum is normal. From the type I to the IV type in the Garden classification, the severity of the femoral neck fracture increases, and the rate of non-healing and the avascular necrosis of the femoral head also increases. The Garden classification has been internationally Widely used. Frandsen et al. asked 8 doctors to perform Garden classification on 100 cases of femoral neck fractures. The results showed that the mutual compliance rate of 8 doctors was only 22%. The dispute over displacement was 33%. It can be seen that the judgment of displacement in Garden classification is closely related to subjective factors. Eliasson et al. (1988) suggested that femoral neck fractures should be simply divided into non-displacement type (Garden I, II type) and displacement type ( Garden III, Type IV).

4AO classification: AO classifies femoral neck fractures as type B in proximal femoral fractures:

Type B1: Upper head type, slightly shifted. 1 insert, valgus 15 ° 2 insert, valgus <15 °. 3 no interpolation.

Type B2: neck-shaped, 1 through the neck base. 2 neck middle, adduct. 3 neck middle, cut.

Type B3: Under head type, shifting. 1 moderate shift, adduction and external rotation. 2 moderate shift, vertical external rotation. 3 significant shifts.

diagnosis

History of trauma, hip pain, unable to stand walking, typical hip flexion, knee flexion and external rotation deformity of the affected limb, the affected side of the large trochanter above the Nelaton line, the horizontal distance between the large trochanter and the anterior superior iliac spine Shortening, X-ray film and CT examination can establish a diagnosis.

Diagnosis

Differential diagnosis

In the differential diagnosis, the main cause of this disease is to differentiate from the intertrochanteric fracture.

Injury postures of femoral intertrochanteric fractures and femoral neck fractures, the clinical manifestations are roughly the same, the two are easily confused, should pay attention to differential diagnosis, in general, intertrochanteric fractures due to local blood supply is rich, swelling, ecchymosis, pain More severe, more severe than the femoral neck fracture; the former's tender point is mostly in the large trochanter, the latter's tender point is mostly in the lower part of the midpoint of the ventral ligament. X-ray films can help identify.

[clinical manifestations]

Symptom

Older people complain of hip pain after falling, do not dare to stand and walk, should think of the possibility of femoral neck fracture.

2. Signs

(1) Malformation: The affected limbs have mild hip flexion and external rotation deformity.

(5) The large trochanter of the affected side is elevated, which is manifested in:

The horizontal distance between the 2 large trochanter and the anterior superior iliac spine on the iliac-ischial nodule (Nelaton line) is shorter than the healthy side.

There are many classification methods for femoral neck fractures, which can be divided into three categories:

1 According to the anatomy of the fracture.

2 The direction of the fracture line.

3 degree of fracture displacement.

The same femoral neck fracture, due to the degree of pelvic tilt, can show different results from Pauwels type I to Pauwels type III on X-ray films. Second, there is no significant correlation between Pauwels classification and nonunion of femoral neck fracture and avascular necrosis of the femoral head. Boyd, George, Salvatore et al found that in 140 patients with Pauwels type I, the rate of nonunion was 0, and the rate of avascular necrosis of the femoral head was 13%. In 295 patients with Pauwels type II, the rate of nonunion was 12% and the rate of avascular necrosis of the femoral head was 33%. In 92 patients with Pauwels type III, the rate of nonunion was only 8%, and the rate of avascular necrosis of the femoral head was 30%. Because Pauwels classification is greatly affected by X-ray projection, it has no corresponding relationship with fracture nonunion rate and avascular necrosis rate of femoral head.

In the Garden classification, from type I to type IV, the severity of femoral neck fracture increased, and the rate of non-healing and avascular necrosis of the femoral head also increased. Garden classification has been widely used internationally. Frandsen et al. asked 8 doctors to perform Garden classification on 100 cases of femoral neck fractures. The results showed that the mutual compliance rate of 8 doctors was only 22%. The dispute over shifting or not is 33%. It can be seen that the judgment of shift in Garden classification is closely related to subjective factors. Eliasson et al. (1988) suggested that femoral neck fractures should be simply divided into non-displaced (Garden I, II) and translocated (Garden III, IV).

4AO classification: AO classified the femoral neck fracture as type B in the proximal femoral fracture.

Type B1: Upper head type, slightly shifted.

1 insert, valgus 15°

2 inserts, valgus <15°.

3 no interpolation.

Type B2: through the neck type,

1 through the neck base.

2 neck middle, adduct.

3 neck middle, cut.

Type B3: Under head type, shifting.

1 moderate shift, adduction and external rotation.

2 moderate shift, vertical external rotation.

3 significant shifts.