Femoral head necrosis, also known as ischemic necrosis of the femoral head or aseptic necrosis of the femoral head, is a common and incurable disease in the field of orthopedics. Femoral head necrosis often affects young and middle-aged patients between 35 and 55 years old, and the disease progresses rapidly. If treatment is not timely or appropriate, 80% of patients will progress to femoral head collapse and femoral head deformation within 1-4 years, thus forcing them to receive artificial joint replacement treatment. However, at the current level of medical care, the long-term efficacy of prosthetic joint replacement in young and middle-aged patients is unclear. Therefore, early treatment is crucial for the treatment of femoral head necrosis, and early treatment inevitably requires early detection and early diagnosis.
1.Diagnosis
The definite diagnosis of femoral head necrosis needs to take into account various factors such as medical history, clinical manifestations and auxiliary examinations.
(1) Medical history
Whether there are common risk factors, such as whether there is a history of trauma around the hip joint, whether there is a history of hormonal drug application, whether there is a history of heavy alcohol consumption.
(2) Clinical manifestations
Femoral head necrosis starts insidiously, and there may be no signs and symptoms in the early stage of the disease, and there are no specific signs and symptoms in the middle and late stage of the disease. The earliest conscious symptoms of femoral head necrosis are mostly vague and dull pain around the hip joint with poor localization, mostly in the lower pelvis, inner thigh and buttocks, radiating to the groin, inner thigh, posterior hip and medial knee, aggravated after long-term standing and walking, and relieved after rest. With the development of the disease, the symptoms may gradually worsen, from intermittent pain to persistent pain, and the pain may increase, and signs such as claudication, local percussion pain, muscle atrophy, and limitation of hip joint movement may gradually appear. Therefore, all patients with suspected femoral head necrosis, especially those with no clear history of trauma, should have their hip joints examined at the same time to avoid missing the diagnosis of bilateral femoral head necrosis.
(3) Ancillary examinations
Auxiliary examinations, especially imaging examinations, have important reference value for the diagnosis of femoral head necrosis. The imaging examination can initially exclude other diseases that cause hip pain, clearly diagnose suspected cases, locate the site of bone lesions, stage cases of femoral head necrosis, detect the effect of treatment, and describe the complications of the disease and its treatment effect. x-ray plain film is highly specific for progressive femoral head necrosis and is the most basic reference for diagnosis and grading of femoral head necrosis. X-ray radiographs of femoral head necrosis may show changes such as femoral head collapse with or without joint space narrowing; cystic changes or speckled sclerosis within the femoral head, flattening of the upper outer part of the femoral head; sclerotic zone with demarcation within the femoral head; translucent zone of subchondral bone (positive crescent sign, subchondral fracture).
MRI has a sensitivity and specificity of 96-99%, and is the most reliable method for early diagnosis of osteonecrosis of the femoral head. The typical MRI changes of femoral head necrosis are T1-weighted images showing a sinuous band of low signal proximal to or across the residual epiphysis of the femoral head, with the low signal band encircling a high signal or mixed signal area, and T2-weighted images showing a double line sign. In addition, coronal and transverse imaging techniques are routinely applied, and MRI can more accurately display the lesion and estimate the volume of necrosis, providing important references for clinical diagnosis, staging, and treatment.
2.Staging
Once the diagnosis of femoral head necrosis is confirmed, the staging should be made. Scientific staging can guide the development of a reasonable treatment plan, accurate judgment of the prognosis, so that the treatment effect is comparable. There are many staging methods for femoral head necrosis, among which Ficat staging and Steinberg staging are most widely used.
Ficat and Arlet divided the femoral head necrosis with clinical symptoms and confirmed by biopsy into four stages according to the X-ray performance.
(1) Stage I has normal X-ray performance.
(2) Stage II has a normal femoral head appearance, but there are obvious signs of bone repair, including cystic degeneration and osteosclerosis. The radiolucent area seen on X-ray shows histologically as a bone resorption area and corresponding fibrous tissue or granulation tissue. The osteosclerotic area histologically appears as new bone overlying the dead bone at the edge of the necrotic area.
(3) Stage III shows collapse of subchondral bone or flattening of the femoral head.
(4) Stage IV shows secondary degenerative changes in the acetabulum such as joint space narrowing and cystic changes, marginal bone formation, and cartilage destruction.
Steinberg staging, also known as the University of Pennsylvania staging, divides femoral head necrosis into seven stages based on the results of X-ray plain film, MRI and bone scan, and subdivides stages I-IV into three sub-stages based on the extent of bone involvement and the degree of femoral head collapse.
(1) Stage 0: Plain films, bone scans and MRI were normal.
(2) Stage I: normal plain films and abnormal bone scans and/or MRI.
①A (mild): <15% involvement of the femoral head.
②B (moderate): femoral head involvement 15-30%.
③C (severe): femoral head involvement >30%.
(3) Stage II: X-ray shows cystic degeneration and sclerosis.
①A (mild): femoral head involvement <15%.
②B (moderate): femoral head involvement 15-30%.
③C (severe): femoral head involvement >30%.
(4) Stage III: subchondral collapse (crescent sign) without flattening of the femoral head.
①A (mild): joint surface involvement <15%.
②B (moderate): 15-30% involvement of the articular surface.
③C (severe): joint surface involvement >30%.
(5) Stage IV: flattening of the femoral head.
①A (mild): articular surface involvement <15% and collapse <2mm.
②B (moderate): joint surface involvement of 15-30% and collapse of 2-4mm.
(③C (severe): joint surface involvement >30% and collapse >4mm.
(6) Stage V: joint space narrowing or acetabular changes.
(7) Stage VI: severe degenerative changes.
3.Treatment
The formulation of a reasonable treatment plan should be based on the stage of necrosis, necrosis volume, patient’s age, joint function, occupation and other comprehensive considerations. The treatment of femoral head necrosis includes conservative treatment and surgical treatment.
(1) Conservative treatment
Conservative treatment mainly includes weight-bearing avoidance, medication and physical therapy. By reducing the pressure on the weight-bearing area of the femoral head, conservative treatment tries to promote local blood supply, reduce inflammation, increase bone tissue density and promote bone and cartilage growth, thus delaying further progression of femoral head necrosis and avoiding femoral head collapse. However, in terms of available clinical evidence, the efficacy of conservative treatment is also quite “conservative”. Therefore, the current view is that conservative treatment is not only difficult to delay the natural course of femoral head necrosis, but also delays the early and reasonable treatment of femoral head necrosis because a certain observation period is needed to evaluate the efficacy after conservative treatment.
(2) Artificial hip arthroplasty
Once the femoral head is heavily collapsed (stage III moderately severe, stage IV, stage V), joint dysfunction and severe pain, artificial hip arthroplasty can be chosen as the treatment. The efficacy of artificial hip arthroplasty in the treatment of advanced femoral head necrosis in the elderly is more certain, but as far as the current medical level is concerned, the long-term efficacy of artificial hip arthroplasty in young and middle-aged patients is still unclear. The main reason is that the artificial hip joint prosthesis has a limited service life and generally needs to be replaced by revision surgery after 10-15 years, which results in poor functional recovery and more complications.
(3) Head-conserving surgery
Head-conserving surgery refers to the surgical treatment that preserves the patient’s own femoral head. This type of surgery can preserve the patient’s own joint, and if the method is appropriate, it can delay or even prevent the further development of femoral head necrosis, thus delaying or even avoiding the treatment of artificial joint replacement. Head preservation surgery mainly includes marrow core decompression, bone grafting, osteotomy and other procedures, among which, the postoperative follow-up results of modified anastomotic free fibula graft are more satisfactory.
In summary, a reasonable treatment plan should be formulated considering the stage of femoral head necrosis, necrosis volume, patient’s age, joint function and occupation, etc. Among them, the stage of femoral head necrosis is the main consideration.
(1) Steinberg stage 0: non-traumatic femoral head necrosis, confirmed on one side, highly suspected or high-risk patients on the opposite side, should be strictly followed up on an outpatient basis, with MRI follow-up every 6 months for early detection and early diagnosis of femoral head necrosis.
(2) Steinberg stage Ⅰ to Ⅲ: perfect relevant examinations, outpatient follow-up by experienced orthopedic surgeons, early diagnosis of femoral head necrosis, once diagnosed, early head preservation treatment by modified anastomotic vascular free fibula grafting, with definite efficacy.
(3) Steinberg stage IV: young and middle-aged patients can be considered for early modified anastomosis free fibula grafting, and avoid or delay artificial hip replacement treatment as much as possible; in elderly patients, artificial hip replacement treatment is recommended, or palliative conservative treatment if the general condition is poor and cannot tolerate surgery.
(4) Steinberg stages V and VI: artificial hip arthroplasty treatment or palliative conservative treatment.