By Robert A. Goodin, M.D.
When conservative measures fail and the pain becomes disabling, the only option is to undergo total hip replacement surgery. The hip joint is a ball-and-socket joint that connects the thigh bone (ball) to the pelvis (socket). We perform a total hip replacement by removing the arthritic ball and placing a metal stem into the femur (thigh bone) and we resurface the socket (pelvis/acetabulum) with a metal shell. The articulation (where the ball and socket meet) can be many different materials, including metal, polyethylene or ceramic. The success of the construct depends on each individual’s body growing into the implants themselves. Once the implants are ingrown they are designed to create a new, smoothly functioning joint that prevents painful bone-on-bone contact.
CURRENT TECHNOLOGY: Advancements in technology allow us to use various materials at the articular surface between the femoral component (ball) and the acetabular component (socket). In an effort to increase the longevity of the implants we have decreased the use of the polyethylene liner and have chosen to use a large head metal-on-metal implant. These implants feature a metal ball that moves against a metal cup. The metal cup is what provides the additional resistance to deterioration and wear. Metal is much harder than polyethylene, and since the metal resists wear better than polyethylene, the metal-on-metal hip can outlast traditional polyethylene-on-metal hips, which is an important consideration for young patients considering hip replacement surgery.
ADVANTAGES: The most important advantages to the current design of the large head metal-on-metal total hip replacement is that the implants combine increased durability, with increased stability and resistance to dislocation by more closely mimicking a healthy joint’s range of motion and stability. Lack of range of motion and stability can lead to impingement and dislocation. The new large head metal-on-metal hip replacement has been designed to provide maximum range of motion before impinging, offering the potential for over 160 degrees range of motion. Larger heads require the head to travel a greater distance before it can “jump” out of the socket, therefore offering greater stability and resistance to dislocation. The large size of the head also allows for better replication of the patient’s normal anatomy. With traditional polyethylene-to-metal articulation, the size of the replacement joint is typically smaller than the original joint. The larger head with current designs creates a more “normal” feel to the replaced hip, which leads to a much more satisfactory outcome and a happier patient. The new technology in hip replacement surgery also allows us to consider hip replacement surgery in a much broader range of patients. The benefit in the elderly patients is the increased stability afforded by the large head articulating with the large metal socket. The younger patients will have the benefit of a much more durable and long lasting hip replacement, which can allow them to resume more active lifestyles following hip replacement surgery.
MINIMALLY INVASIVE TECHNIQUE: Another important advancement in hip replacement surgery currently is the use of minimally invasive procedures. Total hip replacements in the past have been performed through incisions ranging from 16-20 centimeters (roughly 6-8 inches). Advancements in surgical technique have allowed us to decrease the size of the incision to the range of 7 to 12 centimeters (3 to 4 inches).
POST OP RECOVERY and EXPECTATIONS: Patients are able to put full weight on the operative extremity the day of their surgery. By utilizing the minimally invasive technique, preserving the soft tissue surrounding the hip and decreasing the trauma, patients are able to more quickly resume normal activities. Patients are typically in the hospital for about two to three days and many are walking with a cane within two weeks of their surgery. This rapid mobilization has also decreased many of the complications associated with hip replacement surgery, such as blood clots.
FOLLOWING RECOVERY: Many patients will resume extremely active lifestyles. High-impact activities are typically discouraged, but many patients will return to cycling, hiking or playing golf with little or no pain. The ability to resume a much more normal lifestyle following hip replacement surgery, as well as the ability to recover more quickly coupled with the fact that the implants have increased longevity, all allow patients to realistically consider hip replacement surgery no matter what their age.
Image from: Zimmer.com
Robert A. Goodin, M.D. is a Louisville native earning his medical degree and completing his orthopaedic residency at the University of Louisville where he received numerous honors and awards. He has done extensive research and presentations in hip and knee techniques. He is board-certified in orthopaedic surgery and completed an Adult Reconstruction Fellowship at Indiana University Medical Center.
For further information you can go to www.louortho.com or to schedule an appointment you can contact Louisville Orthopaedic Clinic at (502) 897-1794. Address: 4130 Dutchman’s Lane Suite 300, Louisville, KY 40207