We can often come across our loved ones who have fallen and fractured their femoral neck. When they are admitted to the hospital, they are invariably faced with the choice of whether or not to have surgery. The purpose of this article is to try to have a reference when encountering this choice.
1. Fracture of the neck of femur, will the femoral head necrosis without surgery
Almost all doctors, when talking to the family before surgery, will inform them that the femoral head will necrotize after a fracture of the femoral neck. Actually, it will not (except for the fracture line passing through the femoral head). After a femoral neck fracture, the femoral head will not necrotize if no weight-bearing activities are done. There are two main routes of blood supply to the femoral head. One is the central artery. It supplies blood to the top of the femoral head. The other route is the small artery of the joint capsule, which supplies blood to the edge of the femoral head. There is traffic between the vessels of the two pathways. Therefore, after a fracture, the femoral head will not become necrotic as long as there is no weight bearing and no frictional compression between the fractured ends.
In fact, it is not important whether the femoral head is necrotic or not, what is important is whether the femoral neck can still walk after the fracture, the purpose of surgery is not to prevent the femoral head from necrosis, but to walk.
Therefore, the reason for surgery because of femoral head necrosis cannot be justified. But walking is indeed affected after femoral head necrosis. After the femoral neck fracture heals on its own, there is no certainty of femoral head necrosis.
2.The quality of life will not necessarily be improved after femoral neck surgery
The reason for surgery should be considered according to the situation before the fracture person was injured.
If the person was healthy and walking freely before the injury, surgery should be considered. The purpose of surgery is to be able to walk.
If the person was hemiplegic before the injury, the break is almost always on the paralyzed side. There is no need for surgical treatment because even with surgery, you will not be able to walk.
If the fall was not preceded by a neurological disorder and the cause of the fall was a sudden neurological or muscular disorder, surgery is also not necessary.
The quality of life that can be improved by surgery is to be able to walk, not to restore the degree of walking before surgery, but to walk at a discount.
If the patient was elderly before surgery and was able to move on his or her own but already had a staggering gait, he or she may not be able to walk after surgery. The reason why such an elderly person falls is that some of the muscles are not strong enough and are not coordinated. Therefore, surgery is not necessary.
If the patient was a young adult before surgery and had no neurological or muscular disorders, surgery should be considered.
The reason why some patients are still unable to move after surgical treatment is that the patient’s ability to move after surgery was not considered before surgery.
3.The reason why femoral neck fracture does not heal
The main reason is that it is not easy to fix. This is determined by the physiological structure. The femoral neck bears the torsional force from the whole lower limb without bearing weight. According to the principle of leverage, any slight activity of the lower limb, transmitted to the femoral neck, has been amplified. Therefore, it leads to the fact that the femoral neck is not easily aligned and firmly fixed after a femoral neck fracture. Even with internal fixation, it may loosen, after a period of time.
Femoral neck fractures can heal if there is a firm hip fixation method. However, at present, external fixation is not strong except for internal fixation. But internal fixation is more likely to form femoral head necrosis, affecting the postoperative walking.
4.The cause of femoral head necrosis after femoral neck fracture
The most common reason for femoral necrosis after femoral neck fracture is surgery. The femoral head is composed of cancellous bone, and there is only a thin hard skin at the joint surface. The hard skin is covered with a layer of cartilage and a layer of synovial membrane. The cortical bone is surrounded by a honeycomb-like cancellous bone. The cancellous bone is filled with blood and red bone marrow.
During internal fixation, a hole is drilled in the femoral head, which is an artificial re-injury to the cancellous bone based on the femoral neck fracture injury. The threads of the screw screwed into the hole create a third crushing, cutting injury to the cancellous bone of the femur. The latter two injuries occur at almost the same time. Liquefaction of the bone, and regenerative scarring, must occur at all injuries to the bone. The regenerative bone scar is not the original cancellous bone, but a dense bone with disorganized fibers. This is also known as “bone scarring”. The dense bone and the cancellous bone exist in close proximity to each other, and when the force is transmitted differently, the cancellous bone is subject to subtle fractures, which heal to form new scar bone. The gap between the old and new scar bone is the basis for femoral head fragmentation. Generally three internal fixation screws are used. The aggregated diameter of the three screws corresponds to approximately one-third of the diameter of the femoral head. If they are spread out and at a certain distance from each other, the diameter of the scarred bone in the nail path formed by each screw is approximately equal to double the diameter of the screw, and the extent of scarred bone formed by the three screws is close to more than half of the femoral head. This is equivalent to half of the femoral head having been necrotic. If all three screws are close to the articular surface of the femoral head, necrosis of the femoral head after femoral neck fracture is almost inevitable.
The second is the location of the fracture. The closer the fracture line is to the femoral head, the greater the likelihood of necrosis. This is because the closer to the femoral head, the less normal bone tissue remains in the femoral head after removing the scarred bone formed at the broken end of the bone.
So the surgical treatment of femoral neck fracture is the main cause of femoral head necrosis.
5.The choice of femoral neck fracture surgery
After femoral neck fracture due to poor hip fixation, it is difficult to heal and affect walking. Therefore, surgical treatment should be considered after any femoral neck fracture.
Among the patients who are suitable for surgery, the choice of surgical treatment depends on the age and physical condition of the patient.
Younger, fit patients with a long bed-rest base (good physical condition) and a bone healing base should prefer traction repositioning and simple internal fixation. Postoperatively, traction is continued and healing is awaited. The best choice for internal fixation is a Kirschner or Stedman’s pin, which is a steel pin without threads, with little damage and minimal impact on the pediatric epiphysis. It will not affect the growth of the femoral neck. The formed bone scar nail tract is thin and narrow and has minimal impact on the femoral head. The disadvantage is that there is no threaded resistance, the fixation is not firm and the fracture break end is easily displaced. Therefore, traction fixation is still required. Traction fixation only provides relative fixation and does not firmly fix the hip joint. Therefore it is easy to form a non-union of the femoral neck.
If screws, triple wing nails, or screws with a diameter of 10 mm are chosen for fixation, although the internal fixation is relatively firm, it is easy to form osteonecrosis of the femoral head.
A more complex internal fixation is a bone graft with a myotome at the broken end of the femoral neck. The disadvantage is that the fixation is not reliable. Bone healing takes a long time.
In addition to the aforementioned patients and the aforementioned injuries with failed fixation, artificial hip replacement should be considered, which has the advantage of short bed rest. The disadvantage of this procedure is that it has a certain duration of use and needs to be replaced again in young people. People with strong physical rejection will have foreign body reactions or even infections (even if the surgical procedure is aseptic) leading to failure of the surgery.
6.Is the fixation removed after the femoral neck internal fixation?
According to the causes of femoral head necrosis mentioned earlier, if the fixation is more than 10 mm away from the acetabulum, I personally think it is better not to take it out. Because the uneven scar of the bone nail tract left after the internal fixation is removed cannot bear the pressure transmitted by the femoral head, it will audibly shatter and collapse. The internal fixation less than 10 mm from the acetabulum should be removed (this situation of femoral head necrosis will basically occur), lest the collapse of osteonecrosis occur and the screws that expose the femoral head damage the acetabulum.
The development of bone resurfacing devices and internal fixators nowadays has improved the bone healing rate of femoral neck fractures, although there is still no good method for osteonecrosis of the femoral head. Although it is possible to consider the use of an external fixation brace between the pelvis and the femoral stem without internal fixation, which could reduce the incidence of femoral head necrosis. It is just that such a stent is currently only conceived and not yet available.