1. Bone nonunion explained.
Bone non-union is a common complication after fracture surgery, also known as fracture non-union, is the fracture end under the influence of certain conditions, the fracture healing function stops, the fracture end has formed a pseudo-joint. radiographs show that the fracture end is separated from each other, the gap is large, the bone end is sclerotic, atrophy and loose, and the medullary cavity is closed. No matter how long it is fixed, it cannot be connected.
2. The causes of bone discontinuity can be divided into three categories.
Technical factors, biological factors and joint factors.
(1) Systemic factors.
The patient’s metabolic and nutritional status, general health and activity, hormones, drugs, age, gender, ethnicity, nutrition and other factors, such as poor nutrition, weakness or other wasting diseases, or premature postoperative weight-bearing activities, or incorrect functional exercise methods. Recently, it has been reported that smoking can also cause bone discontinuity.
(2) Technical factors.
It is mainly caused by improper treatment methods.
(1) Infection causes necrosis of the fracture end and occlusion of the nutrient vessels, disrupting the normal process of bone scab formation, bone resorption or formation of dead bone, resulting in bone discontinuity.
② Improper treatment separates the fracture end; failure to eliminate unfavorable abnormal activity and stress at the fracture end; muscle contraction force increases the gap at the fracture end, such as ulnar hawk fracture, patella fracture, etc. (ii) Excessive removal of broken bone fragments during open comminuted fracture debridement causing bone defect; soft tissue embedded in the fracture gap.
(③Serious open fractures cause soft tissue damage and affect blood flow to the fracture end, and the incidence of bone discontinuity is also higher, up to 5%-17%. The incidence of osseointegration is four times higher than that of closed reduction due to excessive periosteal stripping. With conventional strong internal fixation and one-stage healing with stress masking, the incidence of blood flow disruption under the plate is higher, and bone resorption after strong internal fixation and re-fracture after removal of the internal fixation are likely to occur.
(3) Biological factors
Sometimes the treatment is appropriate and bone disjunction is due to abnormal biological processes, including impaired crust formation, impaired crust calcification, abnormal differentiation, and abnormal bone remodeling and shaping.
Soft and hard tissue injuries following fractures have the effect of promoting normal bone healing, called regional acceleration phenomenon (RAP). Certain clinical conditions can cause low RAP, including diabetes mellitus, combined peripheral nerve injury, major regional sensory loss from various causes, diphosphoric acidosis, severe radiation injury, and malnutrition. Slow or even non-healing fractures can occur in some patients with one of these factors, ultimately leading to osteonecrosis. More often than not, more than two of these factors may be present in a patient at the same time, thus leading to the occurrence of osteonecrosis.
3.What are the clinical manifestations of osteonecrosis?
(1) Abnormal movement of the fracture end
If the fracture is more than 6 months old and the activity of the fracture end is examined, if there is any abnormal activity, it can be diagnosed as a bone discontinuity.
(2) Pain
Pain when the bone is moved or when weight-bearing is attempted.
(3) Deformity and muscle atrophy
Unconnected fractures may have angulation, shortening and rotational deformity. Joint contracture deformity and muscle atrophy may occur due to prolonged inability to use the limb.
(4) Loss of weight-bearing function
There is loss of weight-bearing function of the unconnected bone after a stem fracture, but some femoral neck fractures have claudication.
(5) Reduced bone conduction tone
The bone is not connected or delayed connection, the bone conduction sound is weaker than the healthy side.
4.Diagnosis of osteonecrosis
In 1986, the U.S. FDA defined osteochondral nonunion as “at least 9 months after injury and fracture, and no further tendency to heal for 3 months”. However, this criterion does not apply to every fracture. Fractures of the long bone cadre take longer to heal and cannot be considered nonunion for at least 6 months, especially if they are associated with local complications such as infection. In contrast, femoral neck fractures can sometimes be diagnosed as osteonecrosis at 3 months.
The diagnosis is confirmed clinically by X-ray examination in combination with the above symptoms. Typical radiographic features of osteonecrosis include
A gap at the fracture end.
Sclerosis of the fracture end with a smooth and clear fracture surface.
Closed bone marrow cavity.
Osteoporosis.
No trabecular formation between bone scabs.
Pseudarthrosis.
The diagnosis of osteochondrosis can be made only when the fracture healing is clinically or radiographically confirmed to have stopped without connection.
5.Treatment of various bone discontinuities
According to the location of the bone discontinuity, the bone discontinuity can be divided into many types, such as the common supracondylar bone discontinuity, tibial stem bone discontinuity, femoral neck bone discontinuity and femoral stem bone discontinuity, the treatment of these parts of the bone discontinuity is also different.
(1) Treatment of supracondylar femoral bone discontinuity: for shorter supracondylar bone discontinuity, treat as fresh fracture, plate or supracondylar screw internal fixation, bone graft with intra-articular short band locking intramedullary needle treatment, can be used to release the osteoporosis at the same time when the plate cannot be used, external fixation + bone graft when the knee joint is severely injured and cannot bear weight and move effectively without pain.
(2) Treatment of tibial stem discontinuity: fibulotomy and weight bearing: the fibula can be amputated 2.5cm, correct the displacement to avoid opening the fracture site to reduce infection and destruction of blood flow tibial stem discontinuity. In case of failure, internal fixation with bone grafting can be performed. A more extensive procedure should be used for tibial stem discontinuity with bone defect, infection or deformity. Posterior lateral grafting: Accessed by the deep fascial gap between the gastrocnemius-fibularis muscle group and the lateral fibularis muscle group. It is simple, lightly injured, and has a high success rate.
(3) Treatment of femoral neck osteoconnection: the principles of surgical treatment are as follows: children and adults under 60 years of age with osteoconnection, when the femoral head has blood flow, angular osteotomy is feasible; children and adults under 21 years of age with osteoconnection, when the femoral head loses blood flow, angular osteotomy and joint fusion is feasible, and in special cases, femoral head or total hip replacement is feasible; hip plate screw system fixation with angular osteotomy is more effective; the effect is related to blood flow and bone The effect is related to blood flow and bone structure, when the head with blood flow can heal, the function is close to normal; some osteotomies are excellent one year after osteotomy, and the function decreases after 3~5 years due to arthritis.
(4) Treatment of femoral stem discontinuity: Most of the femoral stem discontinuity can be cured by intramedullary pinning, closing the needle as much as possible and not removing bone from the broken end. Intramedullary pin fixation of the femoral bone discontinuity can be treated with a coarse intra-medullary pin, or with cortical cutting and plate internal fixation or intramedullary pin treatment of the femoral stem bone discontinuity. The femoral stem defects are treated with locking intramedullary pins + bone grafting, and protective weight-bearing is allowed when the bone fragments are strong enough; large bone defects can be treated with Ilizarov external fixation frame.