Orion - Total Hip Replacement using Direct Anterior Approach (DAA)

What is a total hip replacement (THR)?

A total hip replacement is a surgical procedure to replace the worn-out parts of the hip with an implant. The implant has many parts to it: some are made of titanium, while other parts are made from ceramic or polyethylene, which is a type of plastic.

There are three main ways your orthopaedic surgeon may access your hip joint during the surgery: posterior, lateral, or anterior approach. Regardless of the approach, the positioning and size of the implants must be optimal for a satisfactory outcome and longevity.

Posterior VS Anterior Approach for Total Hip Replacement

I have performed the posterior approach in total hip replacements with good outcomes. Many patients experienced significant improvement in their quality of life after the surgery and were able to return to their active lifestyle, however hip precautions were still required to prevent possible dislocation of the implants.

With the posterior approach, there is a significant risk of the implants popping out (dislocating) if patients squat or cross their legs.

Modern innovations in orthopaedic surgery have introduced a minimally invasive surgical technique in total hip replacement surgery. The direct anterior approach (DAA) has been widely adopted by orthopaedic surgeons across the world because of the several advantages that it yields over traditional hip replacement methods.

At Orion Orthopaedic Surgery, total hip replacement is performed using the direct anterior approach (DAA).

I spent a year in Melbourne on my orthopaedic fellowship learning about the DAA technique of performing the total hip replacement. This technique spares the muscles in the hips, by pushing muscles aside rather than cutting through them to access the hip joints.

This allows a faster recovery and reduces the risk of posterior dislocation of the hip. After the surgery, patients are allowed to kneel, squat, and cross their legs. Another advantage of the anterior approach is that surgeons can assess the lengths of both legs accurately using X-rays.

The direct anterior approach has the following added benefits:

Muscles are pushed to the side during surgery
Patients lying on their backs (supine) during surgery allows accurate assessment of leg length
Accurate X-rays are done to assess leg length and implant positioning
Hip abductor muscles are preserved
Minimal risks of hip dislocation

In a total hip replacement surgery, the worn-out bones and cartilage are carefully removed and replaced with implants. The whole procedure takes about 2 hours. With the DAA technique, patients are encouraged to walk just hours after the surgery and allowed to go home the following day. Our philosophy at Orion Orthopaedic Surgery is to allow patients to mobilise early to prevent muscle wasting and deconditioning.

What are the risks with the anterior approach?

In all surgeries, big or small, there will be a scar when skin incisions are made. There is also a risk of infection which can be mitigated with the use of antiseptics and taking antibiotics before and after surgery.

There is a risk of transient or temporary numbness in the thigh after the surgery due to bruising of the superficial nerves in the thigh (lateral femoral cutaneous nerve). This only affects about 10% of patients and tends to resolve after several weeks.

Patients may also experience an ache in their thigh after the surgery, but this is easily remedied with simple analgesics, physiotherapy, and time. Major complications such as injuries to large blood vessels and nerves are rare, as are fractures of the femur.

At Orion Orthopaedic Surgery, hip replacement surgeries are performed on a simple surgical bed without any traction to prevent major complications such as spiral fractures of the femur and tibia or dislocations of the knee. A blood transfusion is also rarely needed after a hip replacement surgery.

Consultation & assessment

Your orthopaedic surgeon will obtain an in-depth medical history from you and perform a thorough medical examination to determine your symptoms and their impact. More importantly, a list of activities that you can do before and after the injury is crucial for the surgeon to help you restore the function of your hips.

Appropriate imaging such as X-rays and MRI scans are required to give a better idea of the cause(s) of the pain. X-rays are important as they show the bony structures and alignment of your pelvis and hips, whereas MRI scans provide a better imaging of soft tissue such as cartilage, labrum, and tendons in the hips. Both these imaging modalities complement each other and paint a clearer picture for your orthopaedic surgeon to recommend a proper course of treatment for you.

Prior to surgery, pre-operative assessments and investigations are done to ensure that the patient is medically fit for surgery. Your surgeon will also discuss the pros and cons of the procedure, including potential complications and side effects.

During the surgery

Patients are positioned flat on their backs throughout the whole procedure.

The arthritic hip joint is carefully removed with specialized orthopaedic equipment through the acetabulum (cup side) and replaced with a titanium cup. The femur stem is inserted into the femur bone before the hip is reduced into position. This surgery is performed with the use of X-rays to ensure correct size and optimal positioning of all implants.

The orthopaedic surgeon will stress the hip in various directions during surgery to ensure it is stable and does not dislocate. After all actual implants have been positioned, the hip is washed and cleaned to help prevent any infection. The soft tissue is then closed in multiple layers before dressings are applied.

Our physiotherapist will help you on your feet several hours after surgery. This is to maintain muscle strength and restore patient's confidence in his or her new hips. Routine medication for pain, nausea and vomiting will be provided as required.

Rehabilitation post-surgery

After a total hip replacement surgery via the direct anterior approach, patients are encouraged to walk as much as possible. No hip precautions are imposed and patients are allowed to kneel, squat and cross their legs as needed.

Patients are informed that they are not to go for any bungee jumping activities as the strong pull of the rope at their ankles will likely dislocate their hips. It is also best to avoid certain forms of vigorous massage which involves forceful traction of their legs.

Most of my patients are able to drive after 3 weeks - this is mostly based on individual confidence in their own abilities. Simple analgesics like paracetamol or anti-inflammatories are given after surgery to facilitate early mobilization.

I am always happy to hear stories from past patients returning to their favourite physical activities which they were not able to do before surgery. Simple activities such as caring for their grandchildren or having lunch out with old friends are important events that raise our spirit and form the important parts of our lives.

How long do these implants last?

Bringing back the car tyre analogy, it depends on the quality of your tyres, whether all four of your tyres are well aligned, how fast and furious you drive and brake.

The longevity of your implants depends on the quality of the implants, whether they were placed in an optimal position, your age, body weight and the types of physical activities you indulge in.

The hip implants used in Singapore are made in USA and the manufacturing quality and storage techniques have drastically improved over the years. Several countries around the world maintain joint registries to monitor all implants that have been used, allowing for a bird’s eye view on things in the case of defective products or implants.

A majority of patients undergo hip replacement surgery in their early 60s and above. In this phase of life, most patients are retired and do not engage in highly strenuous activities such as marathon running. The stress placed on their implants are therefore mild to moderate. Based on the average lifespan of Singaporeans which is about 85 years, we do expect most implants to be long-lasting. This is especially so if there are no infections, falls or fractures sustained by the patient.

Younger patients below 50 years old can also experience severe wear and tear of their hip due to various reasons (developmental, infection, trauma, alcohol, medication). These patients are generally gainfully employed, enjoy their sports and active lifestyles. The materials of hip implants in a younger patient wound include the use of ceramic bearings, which have been shown to last longer than traditional metal and plastic bearings. Younger patients are at higher risk of requiring revision surgery in future to replace worn out parts of their implants.

Speak to our orthopaedic surgeon if you are having pain and trouble with your hips. We are here to help you on your journey.

FAQs

Can I relieve the pain without hip replacements?
It is possible. The conventional route will involve taking your complete medical history into consideration, as well as perform a thorough medical examination and an X-ray examination. Often this process is adequate to diagnose hip arthritis. An MRI scan of the hip may also be required if the arthritis is in its early stages.

Non-surgical management of hip arthritis include the use of anti-inflammatory medication, physiotherapy, and a slight change in daily activities. An injection containing a local anaesthetic and a small dose of steroid or lubrication is administered into the hip joint occasionally to help temporarily alleviate the pain.

If the hip pain and loss of functions persists despite the management measures put in place, your orthopaedic surgeon will then discuss surgery for the symptoms.

When do you consider hip preservation surgery?
In young patients with hip pain and arthritis, hip preservation surgery is more of an ideal procedure. Depending on the underlying cause of hip pain, the orthopaedic surgeon may decide between arthroscopic labral repairs and microfractures for arthritis, or core decompression surgery for early avascular necrosis (death of bone tissue) of the hip.

Where patients are older or if hip preservation surgery is not an appropriate or practical method, a total hip replacement is preferred.

Procedures

Total Hip Replacement using Direct Anterior Approach (DAA)