Most surgeons use the posterior approach for hip replacement surgery. Recently, however, using the anterior approach has re-emerged as a viable option for certain patients, because it can also be done through smaller incisions using more specialized instruments.
Total hip replacement (THR) surgery (also known as total hip arthroplasty) is regarded as among the most valued developments in the history of orthopedics. The procedure provides a surgeon the ability to relieve pain and restore function to patients whose joints have been destroyed by trauma or disease such as arthritis, and allows a return to daily living, walking, and a life with no (or minimal) pain. In cases requiring total hip replacement, the cartilage becomes worn and the underlying bone develops spurs and various irregularities, which produce pain and loss of motion. In total hip replacement, the cup-shaped hip socket and the ball of the thigh bone are replaced with manmade implants.
Fig. 1: While the image on the left shows the healthy anatomy of the hip, the image in the center details the various signs of arthritis. The image on the right displays a total hip implant and its placement within the hip and upper thigh. Click on each image to view a larger, more detailed version.
To treat end stage arthritis of the hip and hip trauma, total hip replacement surgery has been utilized by surgeons for decades with excellent outcomes over the long term. Since it was first pioneered in the 1960s, the improvements made in this surgical procedure have shown continuous progress in hip function as well as the overall durability of the surgery. A number of studies of knee and hip replacements have shown that after 20 years, 90 percent or greater are still functioning, and after 30 years the rate is about 70 percent. This means that 20 years following the surgery, nine out of ten patients will have a functioning implant and will not need another surgery, and 30 years following surgery, seven out of ten patients will still have a functioning hip implant.
In total hip replacement surgery, an incision is made around the hip joint and the muscles, tendons, and joint capsule are moved away from the joint to expose the femoral head and hip socket (the acetabulum). Next, the head and neck of the femur are removed and the acetabulum is cleaned out in preparation for the cup-shaped replacement component. The channel inside the femur is then prepared so the femoral stem can be fitted into position. Next, a carefully fitted "ball" is secured to the end of the femoral stem. Finally, the hip joint is rejoined and all surrounding tissues are repaired back to the normal position
Surgeons and researchers at Hospital for Special Surgery (HSS), where more knee replacements and hip surgeries are performed than at any other hospital in the United States, continue to contribute to and improve upon the ongoing success of hip replacement surgery. Work is continually underway to develop, evaluate, and refine existing and new procedures and processes. As a result, today there is a range of surgical approaches being utilized by orthopedic surgeons. In hip replacement surgery, the hip can be reached through the back of the hip, (posterior approach), the side of the hip (lateral or anterolateral approach), the front of the leg (anterior approach), or through a combination of approaches.
The posterior approach, the dominant hip replacement surgical method for many years, is used in the majority of the hip replacements performed in the United States. It involves accessing the hip joint via an incision made close to the buttocks. This approach provides doctors with a good view of the hip capsule, allowing for optimum placement of implants. Over the years, doctors have refined this procedure so that it is more minimally invasive, reducing the size of the incisions while maintaining the safety and effectiveness of the technique. This minimally invasive procedure - pioneered at Hospital for Special Surgery - has helped to diminish trauma, reduce length of hospital stay, and limit adverse reactions to anesthesia.
The anterior approach to total hip replacement (sometimes called the "mini-anterior approach" or "muscle-sparing hip replacement") has emerged recently as a viable alternative to the more popular posterior approach. Although it has been in use to some degree since the 1980s, new instrumentation allowing it to be performed using smaller incisions has made it increasingly sought after.
This procedure involves the surgeon making a four-inch incision through the front of the leg, rather than the back (the entry point for the more conventional posterior hip replacement surgery). Frontal entry makes it possible to reach the joint by separating rather than cutting and then reattaching muscles. The anterior hip replacement may also result in a swifter recovery and shorter hospital stay for patients, perhaps due to less muscular damage. Leg length and implant position are also able to be measured with the anterior approach.
Due to the different nature of the approach, there are fewer but different precautions to follow to prevent dislocation, which may occur more often with the posterior approach.
According to Dr. Michael Alexiades, an orthopedic surgeon at Hospital for Special Surgery and an early adopter of the anterior hip replacement technique, “The anterior approach allows for a good view of the hip socket and preserves all muscles. Fluoroscopy is required and one does not have to use a specific implant using this approach. Also, patients undergoing the anterior hip replacement often experience a quicker recovery and shorter hospital stay than with other techniques.”
Disadvantages to the mini anterior hip replacement are both practical and medical. For medical experts, a special operating table or specialized retractors and specific tools are required. Patients also run a slightly higher risk of experiencing femoral and ankle fractures if the special table is used. In addition, due to the approach, there is a substantial risk of a numb, tingling or burning sensation along the thigh, referred to as lateral femoral-cutaneous nerve damage. Patients who have implants or metal hardware in the hip from prior surgery, are muscular, those who have a wide pelvis, or who are very obese may not be well-suited for this procedure and if they do undergo it, it may require longer incisions.
“I will use a minimally invasive approach whenever it will give the best result for the patient,” says Dr. Alexiades. “The anterior hip replacement is relatively new in its new form, so it’s important for patients to find an experienced surgeon to perform their procedure who is also skilled in appropriate patient selection. While many patients are candidates for the technique, it should be used selectively in very heavy individuals, or large men with significant musculature.”
It is important to note that the results of total hip arthroplasty are outstanding in terms of relief of pain and improvement in function. There has been, to date, no clinical study demonstrating the superiority of one surgical approach over another. The possible short term benefits of one surgical approach over another must always be balanced with the possible untoward side effects unique to that approach.
Recently, improvements in surgical technique, instrumentation, and patient selection have made the anterior hip replacement a viable option for patients considering total hip replacement. Currently, if performed by an experienced surgeon on the properly selected patient, an anterior hip replacement can result in a rapid recovery during the weeks after surgery and different precautions for patients to follow to prevent dislocation, which may be more common with the posterior approach. The selection of the appropriate patient for anterior arthroplasty is crucial to the overall success of the surgery. As with all surgical procedures, the advantages and disadvantages of a specific approach should be discussed with your surgeon.
Summary by Andrea Disario