Minimally Invasive Total Hip Replacement
The hip joint is one of the body's largest weight-bearing joints and is the point where the thigh bone (femur) and the pelvis (acetabulum) join. It is a ball and socket joint in which the head of the femur is the ball and the pelvic acetabulum forms the socket. The joint surface is covered by a smooth articular cartilage that cushions and enables smooth movements of the joint.
Hip arthritis is one of the painful and common diseases of the hip joint caused by damage to the cartilage. Total hip replacement surgery is an option to relieve severe arthritis pain that limits your daily activities.
Traditionally, total hip replacement will be performed through a 10–12-inch-long incision made on the side of the hip. A minimally invasive approach has been developed in recent years where surgery is performed through one or two smaller incisions rather than the single long incision as in the traditional approach. Advantages of the newer approach are lesser muscle dissection, minimal pain, quicker recovery, and faster rehabilitation.
Arthritis is inflammation of the joints resulting in pain, swelling, stiffness and limited movement. Hip arthritis is a common cause of chronic hip pain and disability. The most common type of arthritis affecting the hip is osteoarthritis which is characterized by progressive wearing away of the joint cartilage. As the protective cartilage wears down, the bone ends rub against each other and cause pain in the hip. It is more common in individuals aged above 50 years and tends to run in families.
The most common symptom of hip arthritis is dull, aching joint pain and stiffness resulting in limited mobility. There may be pain in the groin, thigh and buttock area and sometimes pain may be referred to the knee. Vigorous activity and walking for long distances can increase the pain and stiffness which may cause limping while walking.
Diagnosis is made by evaluating your symptoms, medical history, physical examination and X-rays. Sometimes, additional imaging tests such as MRI and CT scans may be needed to confirm the diagnosis.
Surgery may be recommended in patients with severe cartilage damage and if conservative treatment options such as anti-inflammatory medications and physical therapy do not relieve the symptoms.
For minimally invasive hip replacement, the surgical technique and artificial implants remain the same as traditional hip replacement however the difference is smaller incisions and minimal soft tissue dissection. The surgery is performed through either one or two smaller incisions. The procedure is performed under general anesthesia.
In single incision minimally invasive approach, your surgeon makes a 3–6-inch incision over the side of the hip to expose the hip joint. The muscles are minimally dissected to reach the joint. The femur is dislocated from the acetabulum. The surface of the socket is cleaned and the arthritic bone is removed using a reamer. The acetabular implant is inserted into the socket using screws or special cement. A liner material of plastic, ceramic or metal is placed inside the acetabular component. The femur or thigh bone is then prepared by removing the arthritic bone using special instruments and shaped to exactly fit the new metal femoral component. The femoral stem is then inserted into the femur either by a press fit or using bone cement. Then the femoral head component made of metal or ceramic is placed on the femoral stem. All the new parts are secured in place using special cement. The muscles and tendons around the new joint are repaired and the incision is closed.
If the surgeon uses the two-incision technique, a 2- to 3-inch incision is made over the groin for placement of the socket and a 1- to 2-inch incision is made over the buttock for placement of the femoral stem. This technique requires longer operative time and is performed under X-ray guidance.
The advantages of minimally invasive total hip replacement as compared with traditional total hip replacement may include:
- Smaller incisions
- Shorter hospital stay
- Less trauma to the surrounding tissues
- Quicker recovery
- Less blood loss
- Less scarring
- Faster rehabilitation
- Minimal post-operative pain
After undergoing minimally invasive total hip replacement, you must take special care to prevent dislocation of the new joint and to ensure proper healing.
- Avoid combined movement of bending your hip and turning your foot inwards
- Keep a pillow between your legs while sleeping for 6 weeks
- Never cross your legs and bend your hips past a right angle (90°)
- Avoid sitting on low chairs
- Avoid bending down to pick up things, instead use a grabber device.
- Use an elevated toilet seat
Risks and Complications
As with any major surgical procedure, there are certain potential risks and complications involved with total hip replacement surgery. They include:
- Injury to nerves and blood vessels
- Formation of blood clots in the leg veins
- Implant malposition
- Fracture of the femur or pelvis
Anterior Hip Replacement
“Arthroplasty” refers to the surgical reconstruction or replacement of a joint.
Direct anterior total hip arthroplasty or replacement is a minimally invasive hip surgery performed to replace the total hip joint without cutting through any major muscles. It is also referred to as muscle sparing surgery because no major muscles are cut enabling a quicker return to normal activity.
Traditionally with total hip replacement, the surgeon makes the hip incision laterally, on the side of the hip, or posteriorly, at the back of the hip. Both approaches involve cutting major muscles to access the hip joint. With the direct anterior approach, the incision is made in front of the hip enabling the surgeon to access the joint without cutting though any major muscles.
Hip replacement is indicated in patients with arthritis of the hip joint.
Arthritis is a condition in which the articular cartilage that covers the joint surface is damaged or worn out causing pain and inflammation. Some of the causes of arthritis include:
- Advancing age
- Congenital or developmental hip diseases
- Previous history of hip injury or fracture
- Increased stress on hip because of overuse
Patients with arthritis may have a thinner articular cartilage lining, a narrowed joint space, presence of bone spurs or excessive bone growth around the edges of the hip joint. Because of all these factors arthritis patients can experience pain, stiffness, and restricted movements.
Your doctor will evaluate arthritis based on the characteristic symptoms and diagnostic tests. Your orthopaedic surgeon will perform a physical examination, order X-rays and other scans, and also some blood tests to rule out any other conditions that may cause similar symptoms.
Direct anterior total hip replacement surgery involves the following steps:
- The procedure is performed under general anesthesia or regional anesthesia.
- You will lie down on your back, on a special operating table that enables the surgeon to perform the surgery from the front of the hip. Your surgeon may use fluoroscopic imaging during the surgery to ensure accuracy of component positioning and to minimize leg length inequality.
- Your surgeon will make an incision, about 4 inches long on the front of the hip. The major muscles are pushed aside to gain access to the joint and perform the replacement.
- Next, the femur bone is separated from the acetabular socket.
- The acetabular surface is prepared using a special instrument called a reamer.
- The acetabular component is cemented or fixed with screws into the socket.
- Then a liner made up of plastic, metal, or ceramic is placed inside the acetabular component.
- The femoral head that is worn out is cut off and the femur bone is prepared using special instruments so that the new metal component fits the bone properly.
- Then the new femoral component is inserted into the femur bone either by press fit or by using special bone cement.
- The femoral head component made of ceramic or metal is then placed on the femoral stem.
- Once the artificial components are fixed in place, the instruments are withdrawn and incisions are closed with sutures and covered with a sterile dressing.
After traditional hip replacement surgery, you would be instructed to follow hip precautions to prevent your new hip from dislocating. These guidelines are very restrictive and include no bending or flexing the hip past 90 degrees, no crossing of legs, use a pillow between the legs when sleeping, and use an elevated toilet seat.
With the anterior approach you will not have to follow standard hip precautions.
Your doctor will however give you instructions to be followed at home for a faster recovery. These include:
- Take medications as prescribed to relieve pain and prevent infection
- Participate in physical therapy to restore hip function and strength
- Eat a healthy diet and do not smoke to facilitate healing and promote a faster recovery.
Contact your doctor if you observe increasing swelling or redness in the operated area.
Risks and complications
All surgeries carry an element of risk whether it is related to the anesthesia or the procedure itself. Risks and complications are rare but can occur. Below is a list of complications that can occur following any hip replacement procedure:
- Infection at the incision site or in the joint space
- Nerve damage
- Hemarthrosis-excess bleeding into the joint after the surgery
- Deep vein thrombosis (blood clot)
- Leg length inequality