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Direct anterior approach is increasingly used as a surgical approach for performing primary total hip replacement. In this technique a regular operating table is used and fluoroscopy is also not required.
It is possible to use this approach for the majority of primary total hip replacements using both cemented and uncemented implants.
Specialised retractors and essential and in this case uncemented implants are used.
Symptoms and examination
The patient will have pain that is arising from the hip joint that is having a significant impact on their quality of life. The pain is most commonly experienced in the groin region and related to activity, weight bearing and rotational movements in the early phase. As it progresses pain is felt more generally around the hip region frequently with radiation down the leg. Progression towards pain at rest or affecting sleep occurs.
Examination of the patients gait will identify a painful (antalgic) limp. The patients leg length should be assessed. The skin of the whole lower limb should be inspected to assess for scars or any skin lesions. The range of movement of the hip should be assessed. It is expected that movement of the hip will induce some discomfort for the patient. In the early stages there may be only discomfort with internal rotation in flexion of the hip and a reduction of this movement in comparison to the non-affected hip. As the condition progresses the hip will become more irritable in all directions of movement and global stiffness of the hip to all directions of passive and active movement. The neuromuscular status of the lower limbs should be assessed. The back and knee movements should also be assessed.
Investigation
A anteroposterior radiograph of the pelvis including both hips is the initial investigation of choice. A lateral radiograph of the hip can also on occasion be useful but is not routinely requested. An assessment of the radiograph will be made for evidence of osteoarthritis. The bone anatomy and shape of the hip is assessed for factors such as acetabular deficiency that would affect the complexity of hip replacement surgery.
If total hip replacement is being considered then templating software is used to plan for the likely range of sizes of implants and the effect of these on leg length and offset in different positions.
In some circumstances a high resolution non-contrast MRI of the hip is required to identify osteoarthritic pattern with the hip which was not apparent on plain radiographic imaging.
When there is clinical doubt of the role of the hip in a patients symptoms then a diagnostic hip injection with a mixture of local anaesthetic and steroid under image guidance can be useful.
Non-operative alternatives
The patient should have completed a trial of conservative management for a reasonable period of time. This should include the use of oral analgesic medication, a weight loss program (when appropriate) and the uptake of non-impact activities (such as a static bike or swimming).
Operative alternatives
The direct anterior approach has a learning curve associated with it. For the first approximate 50 cases it is recommended that the use of this approach is limited to simple cases in slim patients.
Total hip replacement can be performed through a variety of surgical approaches to the hip and the approach the surgeon is most familiar with should be used for more difficult cases until the learning curve has been overcome.
Direct anterior approach total hip replacement can be performed using a specialised traction table.
Hip resurfacing can be considered in appropriate patients and can be performed through a direct anterior approach although the author continues to use a posterior approach for hip resurfacing.
Contraindications
Patients who are not medically fit for a total hip replacement.
Active infection anywhere within the patient.
Complex anatomy may not be suitable for a direct anterior approach for which the surgeon should use the approach he or she feels most comfortable and familiar with.
The patient is positioned supine on the operating table. The table has to be able to break at the level of the hip to enable hip extension. A trial of hip extension is performed prior to any draping. If it is a unilateral total hip replacement then a support is placed against the opposite iliac crest to prevent lateral movement of the pelvis during acetabular preparation and implantation.
Both legs are elevated by an assistant holding the feet and both legs have a preparation and both are draped to allow movement of both legs during surgery.
Two scrubbed surgical assistants are used in this case and are recommended. It is possible to perform the operation with one surgical assistant and that is common practice for the author with some minor alterations to the technique as described here.
Prophylactic antibiotics and LMW heparin and used peri-operatively and post-operatively.
General anaesthesia with a short acting spinal block and local anaesthetic wound infiltration are used.
The patient is encouraged to mobilise as soon as possible after surgery. Frequently, this is on the same day as their surgery. Initially this is with walking aids. No hip precautions are required. The patient is told to not put their hip into extreme positions but can sleep how they wish, sit in a normal seat, and sit in a car. No home adaptation are required.
TED stockings are used and the patient has LMW Heparin for 4 weeks post-operatively.
Patients are discharged on day 1 or 2 post-operatively. They can dispense with walking aids as soon as they feel comfortable to do so.
Simple oral analgesics in the form or paracetamol with the addition of a codeine type medication as required is usually sufficient after the first 24 hours.
Patients can drive as soon as they feel safe to which is usually around the 4th week post-operatively.
Patients are advised to avoid impact activities (such as jogging) for 6 months to allow full integration of the implants.
There have a number of studies published on the direct anterior approach with and without the use of a specialised traction table. A recently published systematic review of the literature concluded that there was a steep learning curve with similar rates of complications, length of stay and final outcomes. Mean outcome scores were better with the direct anterior approach in the first few weeks suggesting advanced rehabilitation. At this time it appears that direct anterior approach offers advantages in the early post-operative phase but this has not as yet been demonstrated in the medium and long-term. It is thus for the individual surgeon to decide on whether to adopt the technique with an acceptance of a steep learning curve and that they must undergo a period of initially cadaver training, surgeon visitation and reverse surgeon visitation at least before embarking on the technique.
Reference
- orthoracle.com
