What is the best approach for Total Hip Replacements?

The Posterior Approach

The Posterior approach to the hip is a well known and tested approach. It was more widely used years ago, prior to other approaches becoming more utilised. The posterior approach is one of the most straight forward approaches to the hip, and was the first approach that I learnt during my training. The posterior approach for total hip replacements remains the most common approach in Adelaide, South Australia, however its popularity is dropping as more minimally invasive approaches are being used.

A patient is placed lying on the side on the operating table and clamps are used at the front and back of the pelvis to ensure that the pelvis remains exactly perpendicular to the ground. It is vitally important to have the pelvis positioned perfectly, or this will impact on assessing the alignment of the final implant. The posterior approach uses a curved incision on the side of the buttock. The first layer to cut through is the fascia which incorporates the attachment of a large muscle called the gluteus Maximus. This is split in line with the fibres all the way down to the pelvis. Once this is opened, it is held open with a retractor to visualise the short external rotators of the hip. Next to the short external rotators is the sciatic nerve, which is the nerve at risk during this approach. This nerve runs adjacent to the short external rotators and supplies motor and sensory function to the leg.

The short external rotators are then cut (3-4 of them) which includes the piriformis, gamelli and obturator muscles. These control external rotation of the hip, and is necessary to reflect from the bone in order to get to the hip. There is no way of performing a posterior approach without cutting these tendons from the bone, although in some less invasive methods, only 2-3 are cut instead of 4. At the end of the operation, these tendons are reattached to the bone to try to get them to heal - often through drill tunnels through the femur, and using sutures.

The hip is dislocated once the tendons are cut from the bone, and the neck of the femur is cut. The rest of the operation is performed in the normal fashion. At the completion of the operation, the nerve is palpated to ensure that a suture hasn't injured it inadvertently or it hasn't been damaged during the replacement by retractors. Once the patient is brought to the recovery room, and Xray is taken to ensure that the implant is enlocated (not dislocated) and in the correct spot. If an adjustment is required, the patient would need to return to the operating theatre for another anaesthetic immediately.

The benefit of the posterior approach is that it is extensile - ie: for complex revision operations requiring extensive work done to the shaft of the femur, this is a good approach for this as it allows the incision to be carried down the leg to perform this. The negative of this approach is the risk of dislocation, and often patients are told not to bend their hips past 90 degrees, cross their legs, squat or place their feet on ledges to tie their shoe laces.

The Lateral (Direct Lateral) Approach

The lateral approach was the first approach I learnt when performing hemiarthroplasty — half hip replacements, where only the ball is replaced and not the socket — as a trainee. A lateral incision is placed on the side of the buttock and the patient is positioned the same way as for the posterior approach. The fascia and gluteus maximus are split in line with their fibres, and then, instead of passing through the back of the hip where the short external rotators sit, the deeper dissection goes through the gluteal muscles. The gluteus medius and minimus are released from the bone and reflected to expose the joint capsule, then reattached to the bone at the end of the operation.

Instead of the sciatic nerve being at risk, in the lateral approach it is the superior gluteal nerve — a motor nerve that supplies the gluteal muscles and the tensor fasciae latae. The steps of the replacement itself are performed much as in the posterior approach, but the muscle repair is critical to a good result. If the gluteal muscles do not heal back to the bone, a patient can be left with a permanent limp. The characteristic finding is a Trendelenburg gait, a recognised trade-off of this approach caused by abductor muscle failure.

The lateral approach is less commonly used for total hip replacement today, and is seen more often when a trainee performs a half hip replacement. Its main advantage over the posterior approach is a lower rate of dislocation; its main trade-off is the risk to the abductor muscles and the limp that can follow if they do not heal.

The Direct Anterior Approach (DAA)

The Direct Anterior Approach is the method Dr Liew uses for all primary total hip replacements. Unlike the posterior and lateral approaches, the DAA accesses the hip joint from the front of the body, working through the natural interval between muscle groups rather than cutting through or detaching any muscle or tendon. This makes it truly intermuscular and internervous — no motor nerve is at risk, and no contractile tissue is damaged during the procedure.

Because no muscles are cut, patients recover differently from the outset. There are no standard hip precautions — no restriction on bending past 90 degrees, no prohibition on crossing legs, no instruction to avoid low seats or certain sleeping positions. The joint is stable from the moment surgery is complete, and early mobilisation — often the same day of surgery when performed in the morning — is routine.

The DAA has been practised in Europe since the 1970s and gained widespread adoption globally over the past two decades. Dr Liew trained in Switzerland and France with surgeons who helped establish and refine the technique, and has performed the DAA exclusively for all primary hip replacements for over eight years. During surgery, the patient lies on their back on a specialised carbon fibre table that allows intraoperative imaging throughout the procedure. This means any small adjustments to implant position can be confirmed and made while the patient is still on the table — before the wound is closed — rather than discovered in recovery.

The incision is typically 5–7cm and, for most patients, sits along the natural bikini line rather than across the lateral thigh or buttock. Recovery milestones — walking, driving at 2–3 weeks, returning to light activity — are consistently earlier with the DAA compared to muscle-splitting approaches. The only nerve at risk during the DAA is the lateral femoral cutaneous nerve of the thigh, which is purely sensory. If transiently stretched, it produces a temporary patch of numbness on the lateral thigh — of minor consequence and typically resolving over weeks to months.

Technology and Surgical Accuracy

The approach is only part of the picture. The accuracy of implant positioning depends just as much on the planning and technology used around the operation. For every hip replacement I perform, the procedure is planned in advance from a three-dimensional model of the patient's own anatomy, and then confirmed again during surgery with intra-operative imaging — so implant position can be checked, and adjusted if needed, before the wound is closed. You can read more about how this works in enhanced accuracy during hip replacement surgery.

I also use single-use instrumentation for hip and knee replacement. These instruments are opened fresh for each patient and are never reprocessed or reused between cases, so every instrument performs to the same specification each time.

The implant itself matters as much as how it is positioned. The choice of bearing surface and materials influences how a replacement is expected to behave over time — explored further in the hip prosthesis I use and the materials in a total hip replacement.

Recovery After Anterior Hip Replacement

Because the direct anterior approach does not cut muscle, early recovery differs from the muscle-splitting approaches described above. There are no routine hip precautions — patients are generally not restricted from bending the hip, crossing their legs, or sitting in lower chairs. When surgery is performed in the morning, most patients stand and take their first steps with assistance the same day.

Walking aids are usually reduced over the first one to two weeks as comfort allows, and many patients are suitable to return to driving at around two to three weeks once they are off strong pain relief and can safely control a vehicle. For a week-by-week picture, see hip replacement recovery week by week and what to expect three months after a hip replacement.

The smaller bikini incision used with this approach sits along the natural skin crease for most patients. Common questions such as returning to running and the longevity of a hip replacement are each covered in their own articles. Every recovery is individual, and your own timeline will depend on your general health, the state of the hip before surgery, and your rehabilitation.

The SuperPATH Method

The super path method of hip replacement surgery is the newest of these approach. It uses a similar pathway to that of placing a nail into the leg when someone fractures their hip. The incision is above the greater trochanter and the gluteus Maximus is split inline with its fibres. The gluteus medius is then retracted forwards, with care not to over traction on this muscle to avoid tearing it from the bone. The initial technique advises surgeons to start by cutting the short external rotators, and then reducing the number of tendons cut to only involving the piriformis, or possibly none, however looking at the approach, it seems almost impossible to achieve without detaching the piriformis. Please note that this is the one approach that I have never performed, however I have studied it extensively to see if it had any advantage to the direct anterior approach.

An interesting point on the brochure was that it stated that the hip is not dislocated during the procedure - this is not unique but also the same as for the direct anterior approach. In fact, this is of little consequence to the stability of a joint, even compared with the posterior approach and lateral approach as the head is still removed in all operations and therefore, the dislocation or non dislocation during preparation is not relevant clinically in any way. 2 incision are required during the super path technique.

"For all primary total hip replacements and for most revision operations, I perform them with the direct anterior approach. We also utilise pre-operative 3 dimensional scanning technology with the production of custom made cutting blocks used to ensure the procedure is performed as accurately as possible. For all hip replacements, intra-operative scanning is performed to check the position of the implants during implantation to ensure that they are positioned as planned. A pneumatic arm aids during the surgery in positioning instruments. Post operatively, patients are allowed to walk the same day of surgery if they are performed in the first half of the day, and the stay in hospital is 3-5 days in general. Most patients are performed under a combined spinal anaesthetic with a light general anaesthetic"

Whilst all approaches to the hip can be good, it is important to select one that your surgeon is comfortable with. Research shows that the best results are obtained when a surgeon is experienced in an approach and utilises that approach for your surgery. Choosing an approach should not be as important as choosing the correct surgeon for your operation. Careful consideration into the risks and benefits should always be explained to you prior to your operation.

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