Osteonecrosis of the femoral head (ONFH), also known as ischemic necrosis of the femoral head (AVN), is a common and intractable disease in the field of orthopedics
Definition: ONFH is a disease in which the blood supply to the femoral head is interrupted or damaged, causing the death and subsequent repair of bone cells and bone marrow components, followed by structural changes in the femoral head, femoral head collapse, and joint dysfunction.
ONFH can be divided into two categories: traumatic and non-traumatic. The former is mainly caused by hip trauma such as femoral neck fracture and hip dislocation, while the main cause of the latter in China is the application of corticosteroids and alcohol abuse.
Diagnostic criteria
Experts suggest to synthesize the diagnostic criteria proposed by the Japan Institute of Osteonecrosis (JIC) and Mont, and develop the diagnostic criteria in China.
I. Main criteria
1.Clinical symptoms, signs and history: arthralgia mainly in the groin and hip and thigh area, limited internal rotation of the hip joint, history of hip trauma, history of corticosteroid application, history of alcoholism.
2.X-ray changes: femoral head collapse without joint space narrowing; sclerotic zone with demarcation within the femoral head; subchondral bone with transverse X-ray zone (crescent sign, subchondral fracture).
3.Nuclear scan shows a cold zone in the hot zone within the femoral head.
4, T1-weighted phase of MRI of the femoral head shows banded low signal (banding type) or T2-weighted phase with double line sign.
5.Bone biopsy shows more than 50% osteocyte vacuolation fossa of bone trabeculae, and involves adjacent multiple bone trabeculae with bone marrow necrosis.
Secondary criteria X-ray shows collapse of the femoral head with narrowing of the joint space, cystic degeneration or speckled sclerosis in the femoral head, and flattening of the outer upper part of the femoral head. MRI shows a band type with homogeneous or heterogeneous low signal intensity without T1 phase.
The diagnosis is confirmed by meeting two or more major criteria. Meeting one major criterion, or ≥4 positive secondary criteria (including at least one positive radiographic change), is likely to be diagnostic.
Key points of each diagnostic method
The diagnosis of femoral head necrosis can be made by asking medical history, clinical examination, X-ray, magnetic resonance imaging (MRI), nuclear scan, computerized tomography (CT) and other methods.
I. Clinical diagnosis Careful medical history should be taken, including history of hip trauma, application of corticosteroids, alcohol consumption or anemia. The clinical symptoms should clarify the pain location, nature and relationship with weight-bearing. Physical examination should include the rotational activity of the hip joint.
Early clinical symptoms of femoral head necrosis are not typical, and internal rotation of the hip joint leading to pain is the most common symptom. After the femoral head collapses, the range of motion of the hip joint may be limited.
Signs :Local deep pressure pain, pressure pain at the stop of the internal rotator muscle, and axial percussion pain may be positive in some patients. In the early stage, the hip joint pain, Thomas sign and 4-character test may be positive; in the late stage, the femoral head collapse, hip joint dislocation, Allis sign and single-leg independent test may be positive. Other signs include limited abduction, external rotation or internal rotation, shortening of the affected limb, muscle atrophy, and even signs of subluxation. If the hip joint is dislocated, the Nelaton line may be displaced, the base of Bryant’s triangle may be less than 5 cm, and the Shenton line may be discontinuous.
X-ray film is difficult to diagnose ONFH in early stage (0, stage I), but it can show positive changes in lesions above stage II, such as sclerotic zone, cystic change through X-ray, speckled sclerosis, subchondral fracture and femoral head collapse. It is recommended to take X-rays in both posterior anterior (orthogonal) and frog lateral views, the latter of which can show the changes in the necrotic area of the femoral head more clearly.
Femoral head necrosis into x performance
The T1-weighted phase of typical ONFH is the residual epiphysis of the femoral head, the meandering low-signal zone near or across the epiphysis, and the low-signal zone wrapping around the high-signal zone or mixed-signal zone. The recommended scanning sequence is T1 and T2-weighted, with additional T2 lipid suppression or short T1 inversion recovery (STIR) sequences for suspicious lesions. Coronal and cross-sectional scans are generally used, and additional sagittal scans may be added for more accurate estimation of necrosis volume and for clearer visualization of the lesion. Roll-enhanced MRI is particularly effective for early ONFH detection.
Fourth, nuclear scan Nuclear scan diagnosis of early ONFH high sensitivity and low specificity. The diagnosis can be confirmed by using 99Tc diphosphate scan if there is a cold area in the hot area. However, the concentration of nuclide alone (hot zone) should be differentiated from other hip diseases. This test can be used to screen for lesions and to look for multi-site necrotic foci. Single photon emission tomography (SPECT) can enhance the sensitivity, but the specificity is still not high.
The CT scan can help to identify the lesion and choose the treatment method.
Femoral head necrosis ct presentation
Treatment of femoral head necrosis
There is no single method to cure ONFH of different types, stages and necrosis volumes, and a reasonable treatment plan should take into account the stage, necrosis volume, joint function, as well as the patient’s age and occupation.
Non-surgical treatment of femoral head necrosis It is important to note that the efficacy of non-surgical treatment of ONFH is still unpredictable.
I. Protective weight-bearing There is still debate in academia as to whether this method can reduce femoral head collapse. The use of double crutches can effectively reduce pain, but the use of wheelchairs is not advocated.
For early stage (0, I, II) ONFH, non-steroidal anti-inflammatory and analgesic agents can be used. For high coagulation and low fibrinolytic state, low molecular heparin and corresponding traditional Chinese medicine can be used, and sodium allantoin phosphate can prevent femoral head collapse.
Physical therapy includes extracorporeal shock wave, high-frequency electric field, hyperbaric oxygen, magnetic therapy, etc., which are beneficial to relieve pain and promote bone repair. Surgical treatment of femoral head necrosis Most ONFH patients will face surgical treatment, which includes two types of surgery, including preserving the patient’s own femoral head and artificial hip joint replacement. Surgery to preserve the femoral head includes medullary core decompression, bone grafting, and osteotomy, and is indicated for patients with ONFH in ARCO stages I, II, and early stage III, with a necrosis volume of 15% or more. If the method is appropriate, artificial joint replacement can be avoided or postponed.
I. Femoral core decompression (core decompression) It is recommended to use a fine needle of about 3 mm in diameter and drill multiple holes under fluoroscopic guidance. Autologous bone marrow cell transplantation and bone morphogenetic protein (BMP) implantation can be performed in conjunction. This therapy should not be used in advanced stages (stages III and IV).
Second, autologous bone grafting with blood vessels There are more applications such as fibula grafting with blood vessels and iliac bone grafting with blood vessels, which are suitable for stage II and III ONFH, and have good efficacy if applied appropriately. However, these procedures may lead to complications in the donor area, and they are very traumatic, have a long operation time and vary greatly in efficacy.
Without vascular bone grafting, there are more applications such as transfemoral rotor decompression bone grafting and femoral head neck bulb decompression bone grafting. Bone grafting methods include compression bone grafting and support bone grafting. The bone grafting materials used include autologous cancellous bone, allograft bone, and bone replacement materials. These procedures are suitable for ONFH in stage II and early stage III, and have better results in the middle stage if applied appropriately.
Osteotomy The necrotic area is moved out of the weight-bearing area of the femoral head, and the non-necrotic area is moved out of the weight-bearing area. The osteotomies applied in clinical practice include internal or external osteotomy and transfemoral rotational osteotomy. This method is suitable for ONFH with moderate necrosis volume in stage II or early or middle stage III. This procedure will bring more technical difficulties for the future artificial joint replacement.
V. Artificial joint replacement Once the femoral head has collapsed heavily (late stage III, stage IV, stage V), and joint function or pain is heavy, artificial joint replacement should be selected. For patients under 50 years of age, limited femoral head surface replacement, metal-to-metal surface replacement, or dual-action femoral head replacement are available. These arthroplasties are transitional procedures that preserve more bone for later revision, but each has its own indications, technical requirements and complications and should be chosen carefully.
Arthroplasty has a positive effect on advanced ONFH, and it is generally believed that non-cemented or hybrid prostheses have better medium- and long-term outcomes than cemented prostheses. Artificial joint replacement for femoral head necrosis is different from arthroplasty for other diseases, and some related issues should be noted.
1, patients with long-term application of corticosteroids, or have underlying disease need to continue treatment, so the infection rate is increased;
2, long-term non-weight-bearing, osteoporosis and other reasons lead to easy penetration of the prosthesis into the acetabulum;
3, had performed preserved femoral head surgery, which will bring various technical difficulties.
In addition, there are: dead bone removal bone cement filling femoral head reconstruction
In addition, there is controversy in academic circles about the treatment of asymptomatic ONFH. Some studies have suggested that ONFH with large necrotic volume (>30%) and necrosis located in the weight-bearing area should be treated actively and should not wait for symptoms to appear.
Treatment options for different stages of femoral head necrosis
For stage 0 non-traumatic ONFH, if the diagnosis is confirmed on one side and stage 0 is highly suspected on the opposite side, close observation is advisable and MRI follow-up is recommended every 6 months.
Stage I, II ONFH if it belongs to asymptomatic, non-weight-bearing area, lesion area <15%, can be closely observed, regular follow-up; symptomatic or lesion >15%, should be actively carried out to preserve the joint surgery or drugs and other treatment.
Stage IIIA, IIIB ONFH can be treated by each implant osteotomy, osteotomy, limited surface replacement, or conservative treatment for those with mild symptoms.
Among patients with stage IIIC and IV ONFH, if the symptoms are mild and the age is young, joint-preserving surgery can be chosen, while other patients can choose surface replacement and total hip replacement.
Efficacy evaluation
The evaluation of the efficacy of ONFH can be divided into clinical evaluation and imaging evaluation. Clinical and imaging changes are not completely synchronized in the same patient, so they should be evaluated separately. Clinical evaluation uses hip function score (e.g. Harris score, SF-36 score, etc.) and should be evaluated on a case-by-case basis according to the same stage, similar necrotic area and the same treatment method. Imaging evaluation can be done by applying X-ray films and using concentric garden templates to observe changes in femoral head shape, joint space and acetabulum. MRI examination data should be available for the evaluation of lesions within stage II.