Total Hip Replacement via Anterior Approach
In recent times much publicity and marketing has been directed towards improved recovery from all types of surgery. Total Hip Replacement via an Anterior Approach is one of these techniques. It has some distinct advantages as well as disadvantages. Dr Balakumar utilises the Anterior approach for most of his total hip replacements and some of his Revision hip surgery.
Total Hip Replacement is an operation which involves removing the diseased joint on both the femur and acetabulum and replacing it with a biological or synthetic joint. With current technology hip replacements are performed with metallic implants. Confusion exists as to what constitutes a total hip replacement. Some patients believe that a mini hip or resurfacing are less invasive and are partial hip replacements. However these are both total hip replacements and are just as big surgically.
Read the related article about Total Hip Replacement
Approach is the method used to access the hip joint for the hip replacement. Other operations around the body have not focused publicly about the approach as much as hip replacements. In the knee for example, up to four different major approaches can be used to access the knee joint. However, this has not been used as a major descriptive factor for this surgery. In the hip traditionally there has been three major approaches. Anterolateral, Lateral and Posterior. The forefather of modern total hip replacements used a modified Lateral Approach (Hardidge) with a bony cut and therefore this approach was popularised around the world.
This operation revolutionized quality of life for human beings unlike no other surgery. However it left patients with a prolonged limp and involved approaching the hip through muscles and required repair of the muscles for full recovery.
The posterior approach overcame the problem of limp by not violating the major hip walking muscles. However it involved transection several hip stabilizers. Both of these approaches were also performed in the sideways position which made measurement during surgery of angles difficult to perform accurately.
This is something that become popular during the 1990s when scar size and cosmesis became an important factor form some patients and doctors. It was the same approach as the posterior or lateral however using specialized retractors and equipment with low profile prosthesis. It theoretically resulted in less tissue damage and quicker recovery. However its main disadvantage was that components were sometimes being mal-positioned requiring further surgery.
An approach that was introduced in the mid 2000’s. This is in essence a posterior approach without deattacment of the posterior stabilizing muscles. However the gluteus maximus is split. This approach has come about as a result of anterior approach to afford posterior approach surgeons some of the perceived advantages of the anterior approach.
This is another approach to the hip joint that was being utilised prior to hip replacement for drainage of infected hips and for non prosthetic treatements for hip arthritis. However when Mr John Charnley introduced hip replacements in England, the two Judet surgeons were also performing their own hip replacements via an anterior approach. The French prosthesis had a high failure rate, and the approach along with the prosthesis did not become popularized. However a few surgeons around the world peristed with the approach using the modern low friction hip replacement.
The approach itself does not cut any muscles. This may seem attractive however it results in poor visualisation of the area being operated on unless specialised equipement, extra assistants and or tables are used in conjunction. The surgeons who persisted in using this approach enjoyed quicker recovery times and enhanced component positioning as they were able to take X-rays during the surgery to verify the position. However the approach was difficult to teach and often resulted in higher complication rates with low volume surgeons.
The modern forefather of this approach was Dr Joel Matta, USA. Over 20 year period was able to show his peers the small but distinct advantages with this approach in the correctly trained surgeon. However as modern day patients become more informed and listen to other patients about their experience, they have seeked out anterior approach hip surgeons. This has resulted in a recent marketing boom about the approach.
Doctors and the industry have used different terms to describe the same approach – Bikini incision, Direct Anterior Approach, Minimally Invasive Anterior, etcetera.
Certain human tissue is unable to repair or regenerate normally, therefore when perfoming surgery it is best to avoid trauma to these tissues. For example, when a patient has a heart attack the heart muscle dies and never recovers. The same applies to nerve tissue and cartilage. However bone has an amazing capacity to regenerate and repair, and hence why we can make an excellent recovery after broken bones. Therefore the ideal hip replacement would be performed via an approach that spared muscle and only cut bone.
This is what the anterior approach offers over other approaches. It is also performed through what is referred to as a internervous approach. This is where the muscles you push aside are supplied by two different nerves and therefore there is no damage to the nerve supply of the muscles. In the other approaches the muscles that are split or cut are supplied by the same nerve so there is often denervation (loss of nerve supply) to part of the muscle.
MRI studies have been performed looking at what happens to muscles via different approaches and certainly this supports some of the marketing hype. However, the patient muscle function seems unaltered between anterior and posterior approaches in most early studies.
Rapid Recovery is often used to describe anterior hip replacements as most patients with this approach can sit on normal chairs, and sleep on their side in the early phase of recovery. They can also drive cars when they are no longer in pain or using analgesia (2 weeks). However again the studies comparing both approaches have not show any difference in these factors at 3, 6 and 12 months.
Improved Stability - There is once again a belief that anterior hip replacements have much lower dislocation rates than any other hip replacements. The reasoning is that muscles are not being cut and that componenets are theoretically being placed in a better position as real time X-rays can be taken to verify the position of the leg. The literature shows 1-5% dislocation rates with posterior approach, and 1-3% rates with anterior. There has been no studies that show a clear difference in the two approaches.
There has been no significant difference between the anterior and posterior approaches except the improved accuracy with leg length and offset with anterior approaches. This has been the biggest source of patient dissatisfaction from this operation.
All other factors have not reached any statistical difference.
A total hip replacement is an excellent operation in the appropriately worked up patient. You as the patient should choose a surgeon you are comfortable with and had opinions about from other patients and health profesionals. The surgeon will then choose the approach that they feel most comfortable with and feel is most appropriate for you. For example if a Tennis player was right handed and tried to play left handed they may have difficulty.
Dr Balakumar feels comfortable using the anterior approach as he frequently performs hip preservation surgeries such as Peri-Acetabular Osteotomies and Hip Arthroscopies. Both of these surgeries are performed on the patients back with real time X-ray. This allows him to use similar principles for his hip replacements. He also performs some of his revision hip surgery using this approach for the same reasons.
There are General And Specific risks of hip replacements that are available.
Infection – the rate of this is between 1-5% dependant on risk factors
Revision – The prosthesis has a lifespan based on use and other factors- generally it has 90% survivorship at 15 years average
Fracture – breakage of bone above or at the level of the prosthesis
Deep Venous Thrombosis or Pulmonary Embolus – Clots in the leg or lung than can be life threatening – 5-10% rate based on risk facots
Dislocation – The joint popping out of its position. This is generally 2-5% based on various studies and risk factors.
Early Loosening – The prosthesis is bonded to the bone via two methods. The first is via cement and the second is through a biological ingrowth of bone into the prosthesis. Dr. Balakumar mainly used uncemented prosthesis relying on the body’s natural growth of bone into the prosthesis. However there can be some early loosening or lack of bonding in some patients with poor bone biology.
Leg Lengthe Discrepancy – Dr Balakumar uses a triple check method to ensure the leg lengths are restored to anatomically similar to the other hip. However in patients with adolescent or paediatric hip problems often the proximal femoral anatomy is already abnormal and therefore the hip replacement is put in a more optimal position. In this situation, the leg can be lengthened or tightened and can make it uncomfortable for the patient in the early recovery phase. Often patients find leg length discrepancy the most difficult problem to deal with and a careful discussion with the surgeon and conservative management is recommended. Rarely revision hip surgery is required.
Nerve injuries to the major nerves in the leg is rare – Sciatic, Obturator and Femoral nerve control the muscles. However upto 50% of patients complain of transient numbness acorss the outer aspect of their thigh with anterior approach as this nerve is stretched during the surgery. This is a skin nerve and usually recovers but can be distressing if one does not expect this.
Pain – Ongoing pain after any surgery can be a enigma, especially as we are performing surgery on patients earlier in their disease process. This can be due to something being wrong or often can be due to muscles around the hip adapting to the new joint. Often the psoas (hip flexor) is cause of pain with anterior hip replacements and one has to treat this conservatively. Rarely surgery is required if the psoas is inflamed (release), or rubbing up against the implants. In some instances dual pathologies such as back problems can contribute to referred pain to the hip.
Metal particle release – This was the major cause of problems with metal on metal hip replacements. However, appropriate patient selection and alternative bearings such as metal on plastic or ceramic on ceramic, or combination of has decreased this. Nevertherless metal particles exist from the rest of the prosthesis but are not shown to be at any toxic level. We are yet to truly know what the effects are of low level metal particles in your body, but it has not be shown to be harmful. High level metal particles can cause local soft tissue reaction and muscle damage. Your surgeon will monitor for all of this during their follow up visits.
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