What Technologies Make a Real Difference in Hip Replacement Surgery? by Boyd W. Haynes III, MD

Orthopaedic & Spine Center

The first successful and reproducible hip replacement surgeries started in the 1960’s, and were used to treat severely painful hips caused by a number of diseases. These ground-breaking surgeries used fabricated metal implants to replace both the femoral bone and head and the acetabulum (socket) in the pelvis. Since that time, hip replacement has been one of the most successfully performed surgeries in the world, with approximately 300,000 being done every year in the United States alone.

During my many years as an Orthopaedic Surgeon, I have seen innumerable changes (most, but not all, improvements) in how musculoskeletal surgery is performed. Advancements in technology have made most of these improvements possible and that certainly holds true when discussing hip arthroplasty (replacement) surgery. In this article, I would like to update you on the scientific advancements that have truly made a difference, not only in the way that I perform surgery, but also in the way my patients tolerate the surgery, recover after surgery and their long-term outcomes.

Component Fabrication – Good for the Patient
Over the past 50+ years, there have been many changes to the implants in terms of the materials used to manufacture them. The metal-on-metal (MOM) implants, which wore badly and released metallic particles into the patient are a thing of the past. Today’s prosthetics have evolved into hybrid models comprised of space-age, plastic like-materials, ceramics and metal alloys, lab-tested for years of wear and stability. Most components can be expected to last many, many years. As we continue to develop stronger, more-lightweight synthetic materials, we can expect to see hip implants that will last for the life of the patient, no matter how young they are when they have their hip replaced or how active they are afterwards.

Component Sizing – Good for the Patient
When hip implant components were first developed, researchers struggled with finding a one-size-fits-all prosthetic. Because there are so many size variations between patients, researchers came up with a few sizes that could be modified to fit the patient intra-operatively. The original design had a large “femoral” head designed to fit into the prosthetic hip socket (acetabulum) snugly, to prevent dislocation. When it was proven that the prosthetics with the larger heads caused large amounts of wear, models with smaller heads were designed and wear rates were greatly reduced. Dislocation was still a significant problem.

Surgical Approach – Good for the Patient
For years, most surgeons used the posterior (rear) approach for hip replacement. At six weeks, most patients had very good results. Getting through the first six weeks, however, was not always easy for patients. Because the posterior approach requires that several muscles in the body be divided, most patients walked with a limp for weeks after surgery, had activity restrictions and dealt with significant discomfort while recovering.

Advancements in technology have made new approaches to access the hip joint a reality. The direct anterior (Jiffy) hip replacement approach was made possible by the development of the Hana table, which allowed surgeons to manipulate the leg of the patient to access the hip joint from the front of the body. This approach allows for the muscles to be moved out of the way, instead of cut, resulting in a much easier recovery for the patient in the first few weeks after surgery. This approach also lessens the likelihood of implant dislocation, as the supporting ligaments, tendons and muscles of the hip are left intact.

Computer-Navigation – Good for Both the Patient and the Surgeon
Experienced Orthopaedic surgeons, who have performed many hip replacements, are used to dealing with leg length discrepancies, correcting alignment and balancing the hips properly during a hip replacement surgery. However, that does not make it easy. Being able to accurately measure and make the appropriate intra-operative adjustments to correct problems requires a surgeon with advanced surgical, as well as, mathematical skills. This is where the computer has made a significant difference. Computer navigation has helped surgeons be more accurate when addressing the “architectural” issues that often need to be fixed concurrently, while doing a hip replacement.

After applying navigation markers to the hip joint, the computer can accurately compute the angle at which the prosthesis needs to be implanted to avoid or address any number of discrepancies which would cause problems for the patient. The most important part of hip replacement is the correct placement of the cup (in the pelvis). Accurate and precise positioning of the cup will prevent hip dislocations. The second most important part is getting the patient’s leg lengths to match and computer-assistance allows me to be more accurate than using X-Rays alone.

A patient of mine was finally able to wear skirts again, because I was able to correct the discrepancy in her leg length. Before hip replacement surgery, her skirts hung unevenly. After having surgery, her skirts hang evenly at the hemline. While this may not matter to all of my hip replacement patients, to her, an even hemline made a world of difference in how she perceived herself and the success of the surgery.

Robotics – Might be Good for the Surgeon
With the advent of robotic surgical-assistive devices, Orthopaedic surgeons have another resource that can help to improve the accuracy and precision of their work in the OR. One such robot is called Rio ®, which is a component of the MAKOplasty ® Joint Replacement System. This system uses a CT scan to map the patient’s joint and create an operative plan BEFORE surgery. During surgery, the surgeon uses the robotic arm, with attachments, to prepare the bone for the joint replacement implant. The computer, which controls the robotic arm, follows the surgical plan and ensures that the surgeon doesn’t remove too much or too little bone. However, this “color-within-the-lines” approach doesn’t allow for some of the unexpected issues that can arise in surgery, which to address appropriately, requires changes be made to the original surgical plan. The robotic technology is still in its infancy and I anticipate that it should only get better with time.

Dr. Boyd Haynes is a Fellowship-trained, Board-certified Orthopaedic Specialist who currently practices at Orthopaedic and Spine Center in Newport News, VA. Named a Top Doc in 2012, 2013, and 2014, Dr. Haynes has a fellowship in Sports Medicine and specializes in total joint replacement and endoscopic carpal tunnel repair. For more information on Dr. Haynes or OSC, please go to www.osc-ortho.com.