Artificial femoral head replacement is an early development of artificial hip replacement. As the name implies, artificial femoral head replacement only replaces the femoral head part, while preserving the normal acetabulum. Compared to total hip replacement, it is less invasive, quicker to recover and less expensive.
The advantages include: better joint movement after replacement, early mobility and reduced complications of long-term bed rest in elderly patients.
Disadvantages include: after a period of replacement, the acetabulum may wear out and total hip replacement may be required.
Surgical indications for artificial femoral head replacement.
It is contraindicated for those who have normal acetabulum with only femoral head lesion. It is only artificial hemiarthroplasty, the specific indications are as follows.
1.Comminuted fracture of the femoral head neck.
2.Age over 70 years old, still performing self-care of daily life and walking before the injury, generally not in a good condition, with life expectancy of not more than 10-15 years.
3, Femoral neck fracture reset failure, unstable internal fixation.
4.The old femoral neck fracture does not heal, the femoral neck has been absorbed, while the acetabulum still remains normal.
5.Patients with femoral neck fracture who cannot cooperate well with the treatment: patients with hemiplegia, Parkinson’s disease, psychiatric patients, etc., performing artificial femoral head replacement can make the patient get up early and reduce complications.
6, benign tumor of femoral head, not suitable for scraping bone graft; for malignant tumor metastasis caused by pathological fracture of femoral neck, artificial femoral head replacement is feasible to reduce patient pain.
Contraindications of artificial femoral head replacement.
1. Elderly and frail patients with serious heart and lung diseases who cannot tolerate surgery.
2.Severe diabetic patients.
3.Septic arthritis or osteomyelitis of the hip joint.
4.Tuberculosis of the hip joint.
5.Severe damage to the acetabulum or obvious degeneration of the acetabulum.
Pre-operative preparation.
1.Comprehensive physical examination to understand heart, lung, liver and kidney functions and proper treatment to adapt to the surgery.
2, the femoral neck fracture should be preoperative skin traction or tibial tuberosity traction, first correct the distal displacement of the fracture and release the contracture of the muscles around the hip joint, in order to reset and reduce postoperative complications.
3.Routine administration of antibiotics before surgery, and avoid injection in the affected area to prevent infection.
4.Preoperatively prepare the skin routinely; enema the night before surgery; fast 12 hours before surgery.
5.Select an artificial femoral head of similar size and place it on the same plane of the affected hip to take x-ray film, then select and prepare a suitable artificial femoral head and a larger or smaller one for backup.
6.Prepare special instruments such as medullary file, artificial femoral head hammer, femoral head extractor, femoral head holder, bone cement, etc.
Epidural anesthesia.
Surgical steps.
1, position lateral prone position with the affected limb on top and the affected hip flexed at 45° to facilitate intraoperative activities in all directions.
2, Incision and exposure can be fully exposed by any route, which can be chosen according to the patient’s condition and operator’s habit. If there is hip flexion contracture, it is appropriate to use the anterior incision. The posterior surgical exposure route is simpler, with less damage, and is mostly used clinically.
3.After incising the joint capsule to reveal the joint capsule, the joint capsule is incised, turned to both sides and the joint capsule at the base of the femoral neck is pushed open, so that the head, neck and base of the femur can be fully revealed.
4.Probe and remove the femoral head rotate the affected limb, probe the femoral head neck fracture, and see the femoral head rotate in the acetabulum, continue to flex and internally rotate the affected limb, so that the distal fracture end of the femoral neck is rotated away, revealing the fracture end of the femoral head left in the acetabulum. The femoral head is removed by drilling into the head with a femoral head retriever, pulling it away from the acetabulum, and cutting the round ligament by reaching between the head and socket with scissors. The diameter of the femoral head is measured and combined with preoperative radiographs to select a suitable size of artificial femoral head. In the case of femoral head necrosis, the hip joint is internally retracted, internally rotated and flexed by 90°, so that the hip joint is dislocated and then the femoral head is removed with a wire saw at the predetermined bone cutting line. All soft tissues in the acetabulum are removed and gauze is used to stop the bleeding. The affected limb is flexed, internally retracted and internally rotated to expose the femoral head neck and medullary cavity to the surgical field.
5. Modify the femoral neck by removing the redundant femoral neck, with the upper end of the incision line starting from the upper edge of the base of the femoral neck. The incision is made inferiorly and ends at 1.0 to 37.5 px above the lesser trochanter, preserving the femoral spur, and the osteotomy is tilted forward 15° to 20° to maintain the anterior tilt of the artificial femoral head after implantation. After osteotomy, the soft tissue around the femoral neck is covered with wet gauze for protection, and a rectangular hole is scraped in the longitudinal axis of the cut surface, corresponding to the base of the stem of the artificial femoral head. A special medullary file is then used to enlarge the medullary cavity to the size of the stem of the prosthesis.
6.Place the artificial femoral head and place the selected femoral head directly in the acetabulum to test whether it is suitable. The head should be the same size as the acetabulum, with free movement and a certain negative pressure when the acetabulum is pulled out. For bone cement reinforced fixation.
7.Reset the artificial femoral head by pulling the limb and pushing the artificial femoral head with fingers, and when it is close to the acetabulum, externally rotate the lower limb to make the head enter the acetabulum. After resetting, test the hip joint in abduction and adduction, and pay attention to the mobility and the tendency of dislocation.
8, Place negative pressure drainage, suture the wound to stop bleeding completely, saline flush, and then intermittently suture the joint capsule with silk thread. A negative pressure suction tube was placed near the artificial femoral head, and a small incision was made on the nearest skin to drain the tube out of the skin. The wound is closed in layers. The drainage tube was fixed and the opening was wrapped with sterile gauze for connection to a negative pressure suction device back to the ward after surgery.
Postoperative treatment.
1, postoperative moving should be careful, maintain the abduction, internal rotation and extension position. Traction of the affected limb in the abducted neutral position for 1 to 2 weeks to prevent inversion and external rotation to avoid dislocation. Later change to orthopedic shoes in the same position for 2 to 3 weeks.
2.Adequate amount of antibiotics should be applied after surgery, and the combination of intramuscular and intravenous should be used until the body temperature is stable.
3, effective negative pressure suction is extremely important, mainly to prevent infection, but also to observe and record the change of drainage fluid color and drainage flow. The drainage tube should not be left in place for more than 72 hours, and the drainage flow should be removed only after 24 hours is less than 20ml.
4, routine x-ray before going down to check the position of the artificial femoral head in the acetabulum, also facilitate postoperative follow-up comparison.
5.After surgery, you should move the unfixed joints, do muscle contraction exercises and massage the lower limbs to prevent deep vein embolism. 2-3 days later, you can sit up and gradually increase the active and passive range; 2 weeks after surgery, the stitches are removed; 3-4 weeks after surgery, you can go down with crutches. Within six months, the patient should walk with the protection of crutches, and the exercise process can be supplemented with physical therapy. After abandoning the crutches, care should still be taken to avoid excessive activity and injury. If there is pain, local inflammation, etc., it should be promptly followed up and treated. Patients with biological fixation should be exercised in bed for 6 weeks after surgery to allow bone tissue to grow into the surface micropores. Then walk with crutches from non-weight-bearing to gradually increasing weight-bearing. In short, moderation of weight-bearing should be noted at all times.
6, strict regular follow-up every 2 to 3 months, so as to guide the exercise. Regular x-ray examination in order to early detection of complications, such as pain, inflammation, should find the cause, timely treatment.