Direct Anterior Approach for Total Hip Replacements
Dr Chien-Wen Liew – Adelaide Orthopaedic Surgeon (Hip, Knee, Shoulder)
The direct anterior approach for total hip replacements is fast becoming one of the more popular approaches for the insertion of a hip prosthesis. The approach itself was developed over 50 years ago for the use in total hip replacements, but was more popularised in the early 1980’s by famous French Surgeon Dr Frederic Laude. Dr Laude was trained under Dr Judet, who is one of the worlds most well known and respected pelvic surgeons. Dr Laude developed the approach as it is used by hundreds of surgeons worldwide. It is a minimally invasive approach in its true sense, not only achieving the desired operation safely, and with a small incision, but with minimal muscle and soft tissue damage under the skin.
Potential Benefits of the Direct Anterior Approach
Whilst the direct anterior approach for total hip replacements is not the most common approach in Adelaide, South Australia, it is the standard of care in France and Switzerland where it has been used successfully for over 25 years. Throughout this time, it has been refined to what it is today – a safe and effective procedure. A surgeon’s experience, and care during the surgery are paramount. These benefits may include some of the following:
- Dislocation risk: As the approach does not require releasing posterior muscles to obtain access to the hip joint, the dislocation profile is different to that of a posterior approach. After a total hip replacement performed via DAA, the rate of posterior dislocation is quite rare. The potential position of any instability is anteriorly. This is generally an unusual position for you to be in. Therefore post operative restrictions are minimal.
- No post operative restrictions: There are minimal post operative movement restrictions after a total hip replacement performed via the direct anterior approach. This is due to the posterior muscles remaining intact. This means that patients are able to sit in a normal chair, use a normal toilet and get in and out of a normal car early in their post operative period. No pillows are used between the legs after surgery, and patients are able to sit up as tolerated immediately following their surgery.
- Blood loss: Whilst blood loss is a normal part of major joint surgery, the direct anterior approach encounters only 1 main vessel – the ascending branch of the lateral femoral circumflex artery. This is a small artery that is specifically found and tied off during the procedure. Its function is to provide blood supply to the femoral head – which is cut out during surgery and therefore does not require the blood supply. As minimal muscles are cut during surgery, bleeding from muscle is minimised. Any total hip replacement has blood loss, so a blood transfusion can be required, although this is very uncommon. A wound drain is inserted during the procedure to drain off the excess blood from inside the joint to minimise pain from the swelling down your leg.
- Pain relief: Total hip replacements alleviate arthritic pain in almost all patients post operatively. The immediate pain relief from the operation is due to technical issues combined with local anaesthetic preparations and nerve blocks. (Anaesthetic regimen developed by Dr Kerr (NSW) in conjunction with Dr Laurie Kohan – orthopaedic surgeon). In general, patients of Dr Liew are given a nerve block, combined with local anaesthetic infiltration. You will wake up with very little pain, and should only require tablet analgesics after your operation. From the moment your muscles regain their function after your anaesthetic, the physios and nurses will encourage you to move your legs and flex your hip.
- Truly inter nervous and inter muscular: The DAA is a truly inter nervous and inter muscular approach to the hip. This means that the interval used to gain access to the hip is between muscles and the nerves that supply them, without specifically cutting through any muscle to obtain access. Inevitably, there is some minor muscle contusion from pushing on the muscle during surgery such as occurs from a bruise – this can cause a bruising type of pain that lasts a few weeks at the most.
- Minor nerve damage: Nerves are at risk during any surgical procedure. In the direct anterior approach the incision and retractors can injury a superficial nerve called the lateral femoral cutaneous nerve of the thigh. This supplies the skin on the side of the thigh with sensation. There are no muscles supplied by this nerve, so muscle dysfunction is not a feature of this approach. In general, 80% of cases where the sensation is affected on the side of the thigh is improved after 3-4 weeks. When it is permanent, this is of no functional detriment to the hip joint or walking.
Dr Liew has trained in and performs all 3 major approaches to the hip – The Direct Anterior Approach, Posterior Approach and Direct Lateral approach. He has a special interest in the direct anterior approach using the AMIS (Medacta) method and uses this for almost all primary total hip replacements performed privately.
With any approach there are potential risks to the approach. This includes surgery with the direct anterior approach:
- Anterior scar. Whilst the scars from a posterior approach are generally out of sight, on the back of the upper leg, there is a visible scar on the front of the leg with the DAA. Often this does not cause significant concern for the patient population involved, but is a consideration for younger patients. In general the wound length from a direct anterior approach is shorter than those of other approaches, however in skilled hands, a minimal incision technique can be performed with other approaches. In some cases, the incision can be made along the line of the groin, however this has no advantages to the hip replacement beneath rather than aesthetics.
- Nerve damage to the lateral cutaneous nerve of the thigh: Whilst this nerve is purely a sensory nerve, in a proportion of people, the nerve can be damaged, resulting in permanent altered sensation on the side of thigh. This only affects the feeling and not any muscle.
- Learning curve: Whilst other approaches are much more common, the direct anterior approach is only just increasing in its usage in Adelaide, and as such few surgeons are currently performing it. Teaching hospitals in South Australia are yet to adopt its usage routinely. Dr Liew believes that dedicated time should be spent learning the approach as it is more technically demanding than other approaches. He believes that it yields enough benefits to warrant the extra time needed to perform the approach. After training with Dr Laude, Dr Dora, and Dr Field in over 150 total hip replacements since adopting the approach, Dr Liew believes that he is able to bring this technical skill back to Adelaide with a vast experience. Dr Liew teaches this approach to senior orthopaedic trainees on a one on one basis, and uses it for all of his total hip replacements performed. Dr Liew is the first Official Australian Efort fellow of Dr Frederic Laude, the pioneer of the approach as it is known today using the AMIS technique.
The current arthroplasty society recommendation (2011) for approaches on the hip found that:
- There are multiple ways to approach a hip joint: none are “new”
- Surgical approach has little influence on results
- There is no scientific evidence that endorses one surgical approach over the other
- Surgeons should tell patients which works best in their hands but should not claim an advantage over approaches used by other surgeons.
Whilst Dr Chien-Wen Liew has a special interest in performing the direct anterior approach for almost all total hip replacements, all patients are encouraged to seek a 2nd opinion to decide what approach is best for them.
For more information on total hip replacements, please contact the office of Dr Chien-Wen Liew on (08) 7099 0188.
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