What are the factors causing failure of internal fixation in PFNA treatment of intertrochanteric fracture of femur?

Intertrochanteric fractures of the femur are more common in the elderly, mostly caused by trauma, with the onset age being 66 to 76 years old. Treatment methods for intertrochanteric fractures are divided into two categories: conservative treatment and surgical treatment. Surgery is currently the preferred treatment method for intertrochanteric fractures. Surgical treatment of intertrochanteric fractures mainly involves intramedullary fixation and extramedullary fixation. Extramedullary fixation is represented by dynamic hip screws (DHS). This method is more stable in fixing the fracture fragments, but the surgical trauma is large and the anti-rotation effect is poor. Intramedullary fixation mainly uses proximal femoral nail antirotation (PFNA). PFNA uses minimally invasive reduction, which has the advantages of short operation time, little damage to the local blood circulation system, and few postoperative complications.


Studies have shown that the PFNA system is beneficial to reconstructing the alignment of the lower limbs and is the most reliable method of intramedullary fixation at this stage. However, with the vigorous promotion of the International Internal Fixation Association and its widespread clinical application, some scholars have discovered that coxa varus deformity, spiral blade excision, and intramedullary nail breakage occurred after PFNA. They also analyzed their failures and concluded that Some risk factors, but the summary of risk factors related to internal fixation failure is not comprehensive. This article will review the current research on the failure of internal fixation of PFNA in the treatment of intertrochanteric fractures, and review the relevant risk factors to provide reference and basis for the correct clinical application of PFNA in the treatment of intertrochanteric fractures.

1. Surgical method and postoperative treatment


After general anesthesia or spinal anesthesia, the patient lies supine on the traction bed, with the affected limb flexed at the hip at 20°, adducted, and internally rotated. The traction table is used for reduction under fluoroscopy, and the ejector rod, bone hook, Kirschner wire, etc. are used for the reduction during the operation. Some irreducible fractures require small incision and open reduction during the operation. After the reduction is satisfactory, PFNA internal fixation is installed according to standard procedures, and the operation is completed after C-arm fluoroscopy confirmation. Patients were routinely treated with prophylactic antibiotics until 48 hours after surgery. Some patients with infections in other parts of the body needed to receive a full course of antibiotics. All patients were routinely treated with anti-osteoporosis and anticoagulant treatments. The patient is encouraged to perform isometric exercise of the quadriceps on the second day after surgery, and perform partial weight-bearing exercises with crutches 4 to 6 weeks after surgery. The patient can be fully weight-bearing without crutches until the fracture is healed upon review.


Figure 1 Patient, female, 65 years old, suffered right intertrochanteric fracture of femur caused by traffic accident. A. Preoperative anteroposterior X-ray showed intertrochanteric fracture of femur, Type IV unstable fracture; B. Anteroposterior X-ray 7 days after operation The radiograph showed that the fracture was well reduced and the internal fixation was stable; C. Anteroposterior X-ray film 12 months after the operation showed coxa varus deformity.

2. Results

The types of internal fixation failure in patients included: ① spiral knife cutting of the proximal femur in 13 cases; ② internal fixation breakage in 2 cases;

③One case of non-union of fracture caused by nail withdrawal by spiral blade;

Univariate analysis showed that gender and osteoporosis had no significant impact on the incidence of internal fixation failure (P>0.05), but unstable fractures, TAD greater than 25 mm, postoperative coxa varus, lateral wall fracture, and incorrect position of the spiral blade Ideal and varying degrees of reduction can significantly affect the incidence of internal fixation failure.


Categorical variables with statistically significant differences in univariate analysis were included in logistic multiple regression analysis. The results showed that postoperative coxa varus and lateral wall fracture were risk factors for internal fixation failure after PFNA fixation of intertrochanteric fractures.

3. Discussion of risk factors for internal fixation failure after PFNA surgery


The risk factors that lead to the failure of PFNA in the treatment of intertrochanteric fractures are currently a hot topic in hip fracture research. The analysis of the risk factors that lead to the failure of internal fixation after PFNA is as follows:

1. Advanced age:
Possible reasons for postoperative internal fixation failure in patients are:
① Elderly patients have poor body compensatory repair ability and have more underlying diseases. They are prone to multiple postoperative complications leading to internal fixation failure.
② Elderly patients are more likely to develop osteoporosis, which indirectly increases the risk of internal fixation failure.

③The muscle strength, quality and function of elderly patients decrease, and various muscle abilities are further reduced due to postoperative pain. The bone plasticity of the proximal femur is poor during postoperative weight-bearing, and the stress on the implant increases, making the internal fixation more likely to fail.

2. Body mass index is too high:
Patients with a body mass index (BMI) that is too high have a higher risk of fractures. The specific reasons analyzed are:
① Patients with a higher BMI bear a greater load on the femoral trochanter. Compared with For people of normal weight, the mechanical effect of the internal fixation (the cutting effect of the spiral blade on the femoral head) changes to a certain extent.
② Tumor necrosis factor and inflammatory factors are higher in obese people than in non-obese people. These factors can stimulate the activity of osteoclasts and inhibit fracture healing to varying degrees.
③Local traction and other reasons during the operation may cause more serious soft tissue damage in obese patients.

④ Obese patients have thicker subcutaneous fat and poor local blood supply, which will affect normal healing to a certain extent.

3. Combined medical diseases:
Elderly patients are combined with one or more medical diseases, and these medical diseases not only increase the risk of intertrochanteric fractures, but also have a significant impact on fracture healing. Analyze the reasons:
① Elderly patients combined with medical diseases , there are many complications after internal fixation, and rehabilitation exercises cannot be carried out in time after surgery.
② Patients with endocrine system diseases lose bone minerals faster, aggravating osteoporosis or prolonging recovery time.

③Most patients with neurological diseases have poor coordination and are more likely to fall after surgery.

Therefore, for patients with medical diseases, intensive postoperative care and treatment of medical diseases are crucial to the prognosis of fractures.


4. Combined with osteoporosis:
Studies have found that osteoporosis, especially severe osteoporosis, not only increases the probability of fractures, but also greatly increases the probability of failure of internal fixation after surgery.
The reasons are analyzed as follows:
① Bone loss in patients with osteoporosis The matrix and bone calcium content are reduced, the microstructure of the bone is degraded, and the fracture healing time is longer than that of normal people.
② Most of the fractures in patients with osteoporosis are comminuted fractures, and the quality of intraoperative alignment is poor, which increases the probability of postoperative hip deformity.
③ The bone tissue structure and biomechanical properties of patients with osteoporosis change, resulting in a reduction in the holding force of the intramedullary nail in the cortical bone, increasing the risk of internal fixation loosening.
④In patients with severe osteoporosis, the enlarged medullary cavity leads to a decrease in the matching degree of the intramedullary nail in the medullary cavity, which also increases the risk of intramedullary nail loosening.

⑤ After internal fixation, patients with osteoporosis have an increased risk of refracture due to abnormal external forces.


5. Unstable fracture:
Some studies believe that unstable intertrochanteric fracture is a risk factor for PFNA internal fixation failure, which may be due to:
① Unstable fracture, poor postoperative alignment quality of the fracture end, and prolonged fracture healing time.
② The femoral calcar cannot conduct compressive stress normally, resulting in increased stress on the internal fixation and an increased risk of coxa varus deformity or intramedullary nail rupture.

③The formation of unstable fractures is closely related to bone density. Most unstable fractures have low bone density, which also increases the risk of PFNA internal fixation failure.


6. Poor intraoperative reduction quality:

Studies have shown that poor intraoperative fracture reduction quality is a risk factor for internal fixation failure, which may be due to:

①The quality of reduction is related to the fracture type. Most patients with poor reduction have more complex fracture types and worse prognosis.

② The quality of fracture reduction is poor, the neck-shaft angle changes, the local stress of the internal fixation increases, and the possibility of the spiral blade cutting out increases.


7. The spire distance is too large:

Studies have found that the lateral wall, as a continuation of the greater trochanter of the femur, is equally important for the stability of the femoral intertrochanteric space. When the integrity of the lateral wall is destroyed, the lateral wall’s ability to support the femoral head and neck bone will be weakened, and the marrow will be damaged. The local force on the internal nail increases, which increases the risk of postoperative failure of PFNA. Therefore, PFNA is not recommended as the first choice for patients with intertrochanteric fractures with severe lateral wall fragmentation.


8. The outer wall is thinner:

The thickness of the lateral wall is extremely important for the stability of intertrochanteric fractures. It is an important component in determining the prognosis of internal fixation of fractures and is currently a controversial research hotspot. Although some scholars have controversy over the measurement method of the lateral wall, most scholars agree that patients with thin lateral walls are more likely to undergo lateral wall rupture during or after surgery, which in turn affects the effectiveness of internal fixation of intertrochanteric fractures. However, there are currently many and inconsistent reports on the critical value of lateral wall thickness. The evidence level of evidence-based medicine in most studies is low, and further exploration by high-quality clinical studies with large samples is still needed.


9. The posteromedial wall is incomplete:

In 1949, Evans proposed the concept of medial wall. With the development of anatomy, it was confirmed that the posteromedial wall of the femoral intertrochanteric space is composed of the femoral calcar and the lesser trochanter. The medial bone cortex of the femoral intertrochanteric space is the most important pressure-conducting part and is the anti-buckling, The integrity of the key part that resists varus is closely related to the stability of the fracture. That is, the more serious the damage to the posteromedial wall, the worse the stability of the fracture. The injury of the posteromedial wall is an important basis for the classification of some intertrochanteric fractures. Studies have shown that the degree of damage to the medial wall is closely related to the failure of internal fixation of intertrochanteric fractures. How to effectively reconstruct the biomechanical stability of the upper femur is still lacking a more unified and effective clinical method.

In summary, advanced age, high BMI, combined medical diseases, combined osteoporosis, unstable fractures, poor intraoperative fracture reduction, excessive TAD, incomplete lateral wall of the greater trochanter, thin lateral wall, and incomplete posteromedial wall Integrity is a risk factor for internal fixation failure after PFNA treatment of intertrochanteric fractures. Although PFNA has many advantages over other fixation methods, attention should still be paid to the high-risk factors that lead to its failure.

① For unstable intertrochanteric fractures with severe osteoporosis, hip replacement should be recommended during the initial surgery.
② PFNA treatment is not recommended for patients with damaged lateral wall intertrochanteric fractures.

③For patients with unstable intertrochanteric fractures, anatomic reduction should be within a controllable range.
④TAD can be controlled within the range of 20~25mm. It is not absolutely required to be in a certain position. This avoids increased intraoperative reduction, fluoroscopy or repeated drilling that may damage the bone due to the pursuit of a precise position.
⑤Patients with serious medical diseases should first treat the related diseases and strengthen postoperative care and functional exercise.

⑥For patients with severe internal and external wall damage, the internal and external wall defects need to be repaired according to the patient’s constitution.


Currently, although there have been many reports about the many factors that lead to the failure of PFNA internal fixation in the treatment of intertrochanteric fractures, we must realize that the reason for the failure of PFNA internal fixation in intertrochanteric fractures is not a single one, but many intertwined and mutual factors. caused by the impact. It is obviously not comprehensive and in-depth enough to analyze or predict the effect of PFNA in the treatment of intertrochanteric fractures only based on a single factor. Therefore, we need more literature to further explore and confirm the associations between these complex factors to provide more comprehensive and accurate guidance.


[1] Wang Xian, Sun Ke, Lin Zhenhua, et al. Analysis of factors related to failure of internal fixation of proximal femoral anti-rotation intramedullary nail in the treatment of intertrochanteric fracture [J/OL]. Chongqing Medicine, 1-7 [2024-03-29 ]. http://kns. cnki. net/ kcms/detail/ 50.1097.R. 20240321. 1856.011.html.

[2] Shi Qiyun, Li Wuyin, Zhang Ying, et al. Research progress on failure factors of internal fixation after proximal femoral anti-rotation intramedullary nailing in the treatment of intertrochanteric fractures [J]. Orthopedics, 2020, 11(03): 262-266.

[3] Huang Minghui, Song Jinliang, Chen Yanjun, et al. Analysis of risk factors for internal fixation failure after dynamic hip screws and proximal femoral anti-rotation intramedullary nails in the treatment of intertrochanteric fractures in the elderly [J]. Chinese Journal of Bone and Joint Surgery, 2019 ,12(10):791-795.


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Post time: Apr-24-2024