Direct anterior approach (DAA) hip replacement surgery

At your initial appointment, your consultant will ask you about your hip pain and perform a physical examination to check your mobility. They will likely need to carry out some imaging tests to better understand and diagnose your condition.

Your consultant will recommend you undergo anterior hip replacement if they think it's the best treatment for your circumstances. They'll explain the procedure and what it involves, including any potential risks and side effects. If you decide you want to receive the treatment, you'll schedule a surgery date.

The surgery is typically carried out under spinal anaesthesia with sedation. General anaesthesia is also possible. Some surgeons use live x-ray imaging to confirm that the placement of the prosthetic components is as accurate as possible. A growing number of surgeons now offer MAKO robotic assisted surgery for their anterior hip replacements.  

The procedure takes place in four main stages:

• Accessing the hip joint: The surgeon makes a small incision at the front of the hip, typically between six and ten centimetres in length. Many surgeons use a slightly oblique, longitudinal incision but, a growing number of anterior hip surgeons offer the bikini incision for women and prefer this incision for high BMI patients. 
  The fatty tissue underneath the skin is held apart and the surgeon separates the underlying muscles, called rectus femoris and tensor fascia lata, at their natural interval. The muscles are simply held apart while the operation takes place. This provides direct access to the underlying hip joint capsule. A flap of capsule is mobilised to provide entry to the joint.  
• Removing the damaged bone: With the hip joint exposed, the surgeon uses an oscillating saw to cut through the femoral neck. The femoral head and the upper part of the femoral neck can then be removed from the hip socket. 

The surgeon then assesses the hip socket to see where the soft fibrous rim (labrum) has been replaced by the growth of new bony projections called osteophytes. The remaining labrum and bony osteophytes are removed from the socket rim to reveal the patients original socket anatomy. 

The surgeon then uses a specialised instrument called a reamer that looks like a hemispherical cheese grater. This is used to remove the remaining articular cartilage and the surface layer of the underlying bone to create a hemispherical recess for insertion of the new hip socket. The surgeon will use reamers of increasing size (usually one milimetre increments) so that the socket can be prepared very accurately, and the diameter of the hemispherical recess is known exactly.

• Fitting the new acetabular socket: A titanium acetabular shell is hammered directly into the hemispherical socket. The prosthetic shell has a very slightly larger diameter than the reamed socket so it fits tightly and cannot budge. The patient’s bone can then grow onto its rough outer surface. 

Some surgeons will also put screws through holes in the titanium shell. The screws pass into the pelvic bone to provide additional hold while the patient’s bone attaches itself to the socket surface. Once the shell is secure, a polyethylene or ceramic liner is placed inside the shell to complete the artificial socket. 

• Fitting the new stem and femoral head: On the thigh bone (femoral side) the surgeon must first find a path through the spongy bone in the upper part of the femur to the marrow canal inside the shaft of the bone. The surgeon then prepares the canal either for a cemented stainless-steel stem or an uncemented titanium stem depending on the patients age, bone density, anatomy and preference.  

When the new stem is securely fixed, a ceramic or metal head is attached to the spigot at the top of the stem. This is the ball that will sit in the acetabular socket. The leg is then repositioned with the ball in the artificial hip socket and the stability of the joint is checked. An X-ray machine can be used to check that the components are perfectly positioned. When the MAKO robot is used, measurements can be made to confirm that planned leg length and hip geometry have been achieved. 

• Completing the procedure: The muscles and fatty tissue that were separated to access the hip joint are put back into position and closed with dissolvable sutures. Finally, the incision site is closed and covered with a sterile dressing. 
  

The anterior hip replacement approach helps rapid post-operative recovery and rehabilitation, getting you back to normal daily life as soon as possible. Most patients can get out of bed and start walking within a few hours of returning to their room. 

The ward physiotherapists ensure that you are safe and confident ascending and descending stairs before they allow you to leave the hospital. Some anterior hip replacement patients are keen to leave the hospital on the day of their operation and, if this is your preference, you should request that your operation is undertaken during a morning operating session. The great majority of anterior hip replacement patients will be ready to leave the hospital after one night in hospital but, if a patient does need a longer hospital admission, this can be accommodated.

You'll receive instructions to aid your recovery, which might include:

• Taking prescribed medications to relieve pain and minimise the risk of blood clots.
• Participating in physical therapy to restore hip mobility and strength
• Eating a healthy diet to promote healing
• Avoiding activities that could delay your healing, such as smoking 
• Contacting your consultant or the hospital’s clinical nurse specialist if you observe excessive swelling or redness at the incision site.