Femoral head necrosis is a common clinical orthopedic disease, according to the statistics of the United States, the annual new cases in 15,000 to 20,000, involving cases in 300,000 to 600,000, as a projection, China’s annual new cases of more than 200,000, the accumulated cases are more considerable. These patients mostly occur in young adults, about 55-60%; they involve both hips. The disease has a high disability rate, and studies of its natural course show that without effective treatment, about 80% of femoral head necrosis will lead to femoral head collapse 1 to 3 years after the onset of the disease, eventually causing severe osteoarthritis and serious hip dysfunction. Femoral head necrosis is not an incurable disease, but patients are often unable to receive scientific diagnosis and treatment, which invariably increases the economic burden of patients. Arthroplasty is the best treatment for advanced osteonecrosis of the femoral head, which can relieve the pain and restore the function of the hip joint in a short period of time, allowing patients to return to work and gain a normal social life. Approximately 20,000 patients in the United States undergo joint replacement surgery for femoral head necrosis each year.
Indications for surgery
For the treatment of advanced femoral head necrosis, the choice of artificial joint replacement should be based on a combination of factors such as the patient’s age and occupation. In advanced stages of femoral head necrosis, where the femoral head has collapsed and osteoarthritis has developed (ARCO stage IV), artificial hip arthroplasty is the only surgical option available.
The relative indications include.
(i) advanced femoral head necrosis with collapse of the femoral head and age > 50 years.
(ii) Although younger than 50 years of age, the femoral head and acetabulum are both involved and osteoarthritis is occurring in combination.
(iii) Stage III (ARCO) lesions with severe pain symptoms at an age greater than 50 years.
(iv) After failed surgery to preserve the femoral head.
Relatively poor indications include.
①Young patients (age less than 40 years), who should strictly grasp the indications and try to choose the femoral head preservation surgery.
(ii) Patients with a high likelihood of failure (those who continue to take high doses of hormones or suffer from severe osteoporosis.
③ alcoholics prone to postoperative dislocation of the hip joint.
(iv) Patients who continue to be treated with dialysis have a high rate of postoperative infection in hip arthroplasty.
Selection of surgical method and prosthesis
For young patients younger than 50 years of age, total hip arthroplasty (THA) with femoral head surface replacement or non-cemented can be chosen, including changing the loading surface to achieve reduced wear of the joint surface (metal-ceramic, metal-metal, ceramic-ceramic). For low-demand patients with metabolic bone disease, a hybrid (Hybrid) or cemented THA should be used. although artificial bipolar femoral head replacement is still used as the main surgical procedure for the treatment of femoral head necrosis in Japan and other countries, its long-term outcome is not promising.
Recently, many scholars have used femoral head surface replacement for the treatment of advanced femoral head necrosis, with the advantages of.
(i) no removal of the femoral head and neck portion, preserving the normal form of mechanical transmission and avoiding stress-obscuring bone resorption.
(ii) the metal surface of the femoral head is associated with the cartilage-related joints of the acetabulum, without abrasive osteolysis.
(iii) The bone volume of the upper femoral segment is preserved, which facilitates the later implementation of revision surgery.
(iv) It is a transitional surgery.
Special considerations that are different from general hip arthroplasty
1. Infection.
Such patients have a history of long-term glucocorticoid use and use of drugs of unknown composition during treatment, and often still need to use glucocorticoids to treat primary diseases after surgery, increasing the incidence of infection after arthroplasty. Countermeasures to prevent the occurrence of infection include: stopping the use of hormones for at least 3 months or controlling the use of hormones to 1 to 2 tablets (5 to 10 mg) of oral prednisone; using intraoperative antimicrobial-containing streptavidin or antimicrobial-containing bone cement; using prophylactic antimicrobials, with special emphasis on maintaining a certain concentration of antimicrobials in the blood during surgery.
2. Bone changes in the acetabulum and upper end of the femur.
Calder’s pathological examination of the bone tissue of the upper end in cases of femoral head necrosis revealed that there were different degrees of osteonecrosis in the bone tissue of the greater and lesser rotors and 4 mm below the lesser rotor, which adversely affected the fixation of the prosthesis. For such patients, the hip arthroplasty and placement of non-cemented acetabulum should keep in mind that the strength of the subchondral bone plate is weak and excessive grinding of the subchondral bone should be avoided to prevent acetabular fracture when the acetabular cup is inserted, and additional screws should be added to fix the acetabulum if necessary after installation.
3.When the femur part has been previously operated to preserve the head.
It should be noted that the shape and bone quality of the proximal femur has changed, resulting in difficulty in inserting the proximal femoral stem and the inability to use the epiphyseal fixed prosthesis.
Long-term outcome of artificial arthroplasty for advanced femoral head necrosis
Femoral head necrosis accounts for about 10% of initial hip replacements. The two main factors affecting the long-term outcome after artificial hip arthroplasty are.
① Patient age: These patients are mostly young and middle-aged men younger than 50 years old, with high daily activity and high quality of life requirements, increased wear and tear of the prosthesis, and high incidence of postoperative joint dislocation and periprosthetic fractures.
②Bone quality: Patients with a history of long-term hormone use or alcohol abuse often combine systemic bone disease, producing osteoporosis or osteodystrophy, which affects the bone growth into the implanted prosthesis and causes early loosening of the prosthesis and sinking of the femoral stalk. There is no significant difference in the outcome after arthroplasty between patients with different etiologies (hormonal, alcoholic, traumatic and idiopathic) of femoral head necrosis.
Artificial bipolar femoral head replacement is simpler, less technically demanding and less invasive than total hip arthroplasty.
Chan compared 28 patients with bilateral femoral head necrosis, one side (Ficat stage III) underwent artificial bipolar femoral head replacement and the other side (Ficat stage IV) underwent THA, both with non-cemented biologic fixation, and after an average follow-up of 6.4 years, there were no significant differences in prosthesis loosening, displacement, occurrence of osteolysis, revision rate and patient satisfaction, indicating that biologic fixation type Artificial bipolar femoral head replacement is an option for the treatment of advanced femoral head necrosis. However, this procedure often causes complications such as pain in the groin area and acetabular bone wear in postoperative patients.
Total cemented THA should be used with caution, especially in younger patients (age less than 50 years), with a high failure rate at long-term follow-up and great inconvenience to revision surgery, and only in older osteoporotic patients.