There are several factors that affect fracture healing.
I. Systemic factors
1. Age: It is well known that children have a strong growth capacity, while the physiological metabolism of the elderly is very slow; therefore, from a single age factor, the younger the age, the faster the healing of its fracture.
2. Activity status.
(1) whole body braking, people who usually prefer sports have good bone strength and it is difficult to have fractures, even if they are fractured, because they are usually in a constant state of motion, the metabolism of the whole body, including the bones, is in a high speed operation, therefore, the nutrients brought to the fracture end and the speed of taking away metabolic waste is fast, so the fracture healing is also fast. Conversely, it is slow.
(2) Space flight, space pilots in weightlessness, their bones do not receive the stimulation of normal gravity, so the healing ability is much worse.
3, nutritional status: good nutritional status can provide the protein, calcium and other components needed for fracture healing, the healing phase will be much better, therefore, for patients with fractures in the process of weight loss, and finally give up the excessive pursuit of the concept of “thin is beautiful”, first to ensure that the normal physiological needs.
4, endocrine factors: growth hormone, corticosteroids, thyroid hormone, estrogen, androgens, calcitonin, parathyroid hormone, prostaglandins and so on will have an impact on fracture healing.
5, disease: diabetes, anemia, neurological diseases, wasting, etc. affect the healing of fractures.
6, vitamin deficiency: for fracture healing also has a negative impact.
7, drugs and other substances: such as nicotine, alcohol and other factors.
8.Nervous system injury.
Second, local factors
1.Factors not related to injury, treatment or complications
(1) Type of bone: some bones in the body have poor blood flow, and once fractured, it will be difficult to heal. For example, femoral neck intracapsular type fracture, hand navicular fracture, lower calf fracture, etc.
(2) Abnormalities of bone: bones in abnormal state, their regeneration ability after fracture is also reduced at the same time. For example, radiation necrosis, infections, tumors and other lesions, etc.
(3) loss of innervation: nerves control the surrounding tissues while also producing a growth stimulating substance for the surrounding tissues, called nerve growth hormone, which regulates the healing ability of the tissues
2.Factors related to the injury
(1) The degree of local damage.
(1) The healing ability of open fractures is lower than that of closed ones.
(ii) The higher the degree of fracture comminution, the higher the fracture healing.
(③) The speed at the time of injury; the severity of the damage to the tissue by high energy external forces.
(iv) low circulating levels of vitamin K1.
(2) The extent of destruction of the blood supply to the bone, fracture segment (AVN of large vessels) or soft tissue; the reduced healing ability of the severity of the injury.
(3) Type and site of fracture (one- or two-bone fracture, e.g., tibiofibular or tibial alone); reduced healing capacity in one of the multiple fracture segments.
(4) Bone defect: statistically, every 1 mm defect in the fracture end prolongs the healing process by at least one month.
(5) Soft tissue embedment: it hinders the passage of normal bone scab.
3.Factors related to treatment
(1) The extent of surgical trauma: The current emphasis is on minimally invasive surgery whenever possible, with the aim of improving reducing the healing time of the bone.
(2) Blood flow changes caused by the implant: the application of the internal fixation can cause blood flow disorders to the surrounding bone and affect healing.
(3) Internal or external fixator stiffness and type: stainless steel internal fixation material can cause stress blockage for bone due to high fixation strength and high elastic modulus, which reduces normal stress stimulation and limits bone growth.
(4) Bone end contact situation (gap size, misalignment, overdrawing): there are relatively more healing points between fracture ends with large contact area and good healing ability.
(5) Factors stimulating post-traumatic osteogenesis: bone graft, bone morphogenetic protein (BMP), electrical stimulation, etc., all have effects on the fracture end, so the application of certain electrical stimulation, bone graft and bone morphogenetic protein (BMP) that promote fracture healing all have positive significance for fracture healing.
4. Factors related to complications
(1) Infection: There was a notion that infection was a good stimulus for fracture healing, but the disadvantages of infection far outweighed the benefits compared to the adverse effects of infection itself. However, now inactivated Staphylococcus aureus has been made into a drug that is annotated directly to the fracture end to promote bone to healing.
(2) Venous stasis: Patients with deep vein embolism have poor venous return and slow removal of metabolic waste from the fracture end, which affects fracture healing.
(3) Metal allergic reaction: Metal allergic reaction affects the local to microenvironment, which affects the healing of the fracture.