Anterior Approach Total Hip Replacement
The Anterior Approach Hip Replacement, or Direct Anterior Hip is a surgical procedure that is gaining worldwide acceptance as an alternative technique to standard hip replacement. A current conservative estimate is that 20% of hip surgeons are now utilizing this technique in select patients for primary hip replacement.
The Anterior Approach implies an approach from the front, as opposed to a more traditional side approach to the hip. The hip is accessed in a naturally occurring interval between muscles as opposed to cutting or splitting through them. The technique uses the same implants as traditional hip replacement or resurfacing procedures.
What are the Advantages of Anterior Approach Total Hip Replacement?
The Anterior Approach for hip replacement offers some unique advantages over traditional techniques. Advantages of the anterior approach include:
- Quick recovery
- Low dislocation rate
- Improved surgeon control of implant position
Most traditional hip replacements are generally done with the patient lying on his/her side. The approach and incision is made from the side or lateral aspect of the patient. Nearly all of the techniques require that the gluteal muscles to be cut or split. These muscles are some of the most powerful in the body and are required to walk with a limp-free gait. Surgery that injures these muscles put the patient at risk for a longer recovery or a permanent limp. The Anterior Approach preserves the gluteal muscles which makes recovery quite fast. Many patients can leave the hospital after a short overnight stay, or even the same day. Many begin walking immediately. Normal stair climbing and more athletic pursuits commonly resume in a matter of days as opposed to weeks or months with standard techniques.
A common problem of traditional hip replacement surgery is dislocation. This is a problem where the ball “jumps” out of the socket. The prosthesis comes uncoupled deep within the body. The patient has agonizing pain and generally is unable to get up off of the floor to walk. Generally this occurs when the patient goes to sit in a low chair or on a toilet. In some cases it happens when the patient bends over or rotates their leg. Generally the patient must have the prosthesis “put back in” by a trained medical provider, this procedure is called a “closed reduction”
By leaving important muscles intact, the hip is more stable and less likely to dislocate.
While having a dislocation does not always mean the hip will go on to have a bad outcome, if dislocations become recurrent then repeat surgery is required to hold the hip in place. There is debate over the actual dislocation rate in traditional hip replacement surgery. In the case of a very good surgeon, with modern implants one may expect very low dislocation rates. However a recent study showed that dislocation still exists as the most common cause of revision surgery in the US.
The Anterior Approach has some advantages in dealing with dislocation. During the anterior approach the muscles that support the hip are generally left intact. By leaving these important structures intact, the hip is more stable and less likely to dislocate. Studies have demonstrated very low dislocation rates with the technique.
Commonly following traditional hip replacement the patient is told not to bend at the hip or rotate the leg for six or eight weeks following surgery. These positional restrictions are commonly called “hip precautions”. With anterior approach hip replacement hip precautions are generally not required because the muscles around the hip are left intact. When these muscles are cut as in traditional hip replacement, a surgeon may employ hip precautions to protect the surgical repair of these muscles.
Anterior hip replacements produce reliably well positioned hips
Likely the strongest reason for the growth of the anterior hip replacement nationally is that it produces a reliably well positioned hip. A common problem with all minimally invasive techniques of hip replacement has been problems with getting the implants correctly positioned. With reduced visualization it is no small task to get things like cup position or leg length correct. The anterior approach allows the patient to be operated while lying on their back. This facilitates the use of X-ray in surgery. The table that is commonly used for anterior hip replacement is made of carbon fiber allowing one to shoot an X-ray through it. By using the anterior approach and X-ray to guide the surgeon, the final product of a well-positioned hip can be reliably achieved.
Are there Disadvantages to the Anterior Approach Hip Replacement?
The biggest disadvantage of the anterior approach for hip replacement is that it has a significant learning curve for most surgeons. The technique is difficult compared with traditional approaches. It takes a surgeon many cases to become proficient with the technique to avoid complications. Some studies have advocated that a minimal case exposure of 100 cases is required before a surgeon may be considered proficient in the technique. Complications rates between anterior hip replacement and traditional hip replacement are comparable. Unfortunately, in the hands of surgeons with inadequate training or exposure to the technique, significant and severe complications can be expected. Thankfully, courses and opportunities for advanced study in anterior approach hip replacement are increasingly available to surgeons so that they may better their training and exposure in a safe and monitored environment.
Nerve injury can be a significant and life-altering complication of both traditional hip replacement and anterior approach hip replacement. In cases where the sciatic or femoral nerve are injured there is generally a component of injury which makes it hard to move the leg or foot. This is called a “palsy” or “foot drop”. There doesn’t appear to be an increase of this rare complication using the anterior approach.
The anterior approach is an overwhelmingly successful procedure
Nearly all patients undergoing anterior approach hip replacement have some injury to a sensory nerve that innervates the top of the thigh. About 80 percent of patients undergoing anterior hip replacement report some numbness to touch along the top of the thigh next to the incision. This is largely due to retraction of a nerve called the LFCN, or lateral femoral cutaneous nerve of the thigh. This nerve gives sensation to the top of the thigh. This nerve lies immediately adjacent to the incision in anterior hip replacement. During the procedure, the nerve is stretched which leads to some numbness. In general these symptoms diminish over time. However, if tested there will usually be some residual numbness next to the incision. There is no functional limitation as it relates to this numbness experienced after surgery. Most patients are quite happy with their hip function, but when questioned report having some numbness near the incision.
Femoral fracture is a complication of hip replacement that can occur with any approach. With the anterior approach, exposure of the femur can sometimes be challenging. There have been higher reported rates of femoral fracture with the anterior approach. In the obese or very muscular patient, or in those with severe osteoporosis may make this more likely to occur. The risk of femoral fracture is experience dependent, meaning the more cases a surgeon has done, the less likely a fracture will occur. Again, the lowest risk for fracture is in the hands of surgeons with numerous case experiences.
The lowest risks are in the hands of experienced surgeons
If a femoral fracture occurs during anterior approach surgery, the key to a good outcome is prompt recognition of the complication. The most common treatment is to pass a cable around the femur and secure it before reseating the implant. The cable secures the fracture and prevents its further displacement. With this treatment most patients can go on to have very good outcomes.
While complications can occur with any technique, the anterior approach for hip replacement is an overwhelmingly successful procedure. A thoughtful discussion with your surgeon about the risks and benefits as they relate to your specific case is warranted.