Direct Anterior Hip Replacement (DAA-THR)
Direct anterior approach total hip replacement is sometimes known as anterior minimally invasive total hip replacement.
The Direct Anterior Approach (DAA) for total hip replacement continues to be recognized for its minimally invasive nature, potentially leading to faster postoperative recovery and reduced muscle damage. This technique involves a smaller incision made at the front of the hip, allowing surgeons to access the joint without detaching muscles or tendons. The direct anterior approach can facilitate a quicker functional recovery and diminish post-operative pain compared to more traditional approaches that require larger incisions and manipulation of muscles.
Dr Reddy has a strong preference for this approach specifically for its advantage in restoring limb lengths accurately, proven decrease in incidence of hip dislocation or instability and for the enhanced recovery pathways it enables. However he also recognises that it is not a suitable approach for every patient with hip osteoarthritis. The decision regarding approach to be utilised is ana individualised one and Dr Reddy will discuss the best options for your specific hip at your consultation. At the end of the day the outcome of your hip replacement surgery depends on sound surgical technique and optimal peri-operative care; and not so much on the approach utilised.
What does ‘direct anterior approach’ mean – is it a new invention?
Total hip replacement (THR) is a hugely successful operation to relieve pain and improve or restore function, mobility, activity, and quality of life.
THR can be performed through different approaches:
- Posterior approach: This is where surgeons approach the joint from the back of the hip. It is an excellent and reproducible approach but involves detaching the posterior capsule and some muscles/tendons that are repaired later. There is increased incidence of hip dislocation compared to other approaches, some of which require reoperation.
- Direct lateral approach: Requires detachment and later reattachment of the hip abductor tendon. Limp and gait abnormalities are more common with this approach which usually resolve with time.
- Direct anterior approach: Though this is not a new approach, its benefits in THR have been more widely realised in recent years. It involves small incision in the front aspect of the hip and exposing the hip joint through inter-muscular planes.
What are the benefits of direct anterior approach in total hip replacement?
- Key benefits include reduced incidence of hip dislocation/instability and the ability to achieve and verify accurate restoration of limb lengths. This usually results in better functional outcomes. Published medical studies have also shown that DAA patients performed better in the early postoperative periods with lower pain scores and had more patients walking unlimited and climbing stairs at six weeks (though there are no statistically significant functional differences in later periods).
- Enables Enhanced Recovery Pathway after THR. Associated with earlier mobilisation and decreased postoperative pain.
- Less hip precautions required. Traditional precautions following THR using posterior approach include avoiding sitting in low chairs, bending, and raised toilet and car seats. These precautions are not required with DAA-THR. No postoperative pillow use is required with DAA. The only recommended precaution is to avoid external rotation beyond 45 degrees. As a matter of fact, stability during DAA-THR is checked with external rotation to 90 degrees so 45 degrees is well within stability limits.
- Less muscle damage with DAA compared to other approaches in biochemical and MR imaging studies.
What are the challenges and risks with direct anterior approach to hip replacement?
The main challenge with surgeons adopting DAA-THR is the long learning curve. Exposure of the femur and proper implantation of the femoral component is technically challenging and requires systematic training, skill, and experience. Results from the Australian National Joint Replacement Registry found that rate of revision surgery for complications is slightly higher during this learning curve.
Injury to lateral femoral cutaneous nerve has been well published in literature, but this can be minimised with careful technique and due diligence. Increased incidence of greater trochanteric and calcar (proximal femur) fractures has been reported, more so in the surgeon’s learning curve.
The approach is also difficult in very muscular patients as well as obese individuals. Certain anatomic characteristics of the hip joint also make this approach difficult.
Dr Reddy is trained and experienced in DAA-THR and offers it to most of his patients, having performed hip replacements for 20 years now and utilising the DAA techniques since 2019.
For an unbiased overview of surgical approaches in THR, here is what the Arthroplasty Association of Australia said in its Position Statement on Hip Replacements in October 2016:
- There is no published level 1 (highest level) scientific evidence that endorses one surgical approach over the other.
- The different surgical approaches have advantages and disadvantages which may be patient specific. No surgical approach is without risk.
- Surgical approach has little influence on results in the short or long term.
- A long-lasting and successful result can be achieved with a THR done through any number of different surgical approaches.
- Patients are well advised to allow the surgeon to decide which approach is most appropriate in their case.