Problems With Hip Replacements
It is often the case that research results as they are published are far behind actual knowledge in medicine. And changes in medical (clinical) practice by the majorityof health care professionals is delayed even more. To combat this, many orthopedic surgeons rely on annual meetings to keep them as up-to-date as possible.
In this specialty update, current information on total hip arthroplasty (THA, otherwise known as a total hip replacement) is summarized. The ideas presented were first offered at the 2009-2010 meetings of the American Academy of Orthopaedic Surgeons, the Orthopaedic Research Society, the Hip Society, and the American Association of hip and Knee Surgeons.
Surgeons agree there are still many problems to overcome when it comes to hip replacement surgery. Two of the biggest dilemmas faced right now are the increasing number of older adults who need joint replacements and fewer surgeons specializing in this procedure. Some surgeons are shying away from hip replacement surgeries because of the high costs. There have been problems with the implants holding up. Product liability is a huge factor in this issue.
It seems like the outcomes of hip replacement are less predictable and worse now than ever before. One of the reasons for this may be the fact that so many surgical techniques are available now. Which method works best for each individual patient problem has not been determined. Problems such as bone deficiency, infection, and hip dislocation add to the many challenges faced by patient and surgeon.
There are also many more implant designs and materials to choose from. For example, more porous materials like titanium foam, cobalt-chromium foam, and tantalum foam are available. These materials make it easier for bone to fill in and around the implant to help hold it in place. The surgeon can also use cement and/or bone grafting to help seal the implant in place. All of these efforts are geared toward one thing: preventing loosening of the implant -- the most common complication of hip replacement.
Research has focused on ways to prevent implant loosening. Some surgeons have advised their patients to limit physical activities the first 12 months after receiving a hip replacement. Others have suggested low-impact sports over high-demand activities. Some studies have concluded that patient selection is really the key factor here. By looking at who ends up requiring revision surgery, it's possible to make some observations that might help.
For example, the revision rate is higher for women than men and in patients who receive smaller-sized implants. Hip resurfacing has higher revision rates than total joint replacement, especially for older patients. Getting the cup part of the hip replacement seated in the right place with the correct angle seems to be a key ingredient to success.
One of the new tools in the pipeline for surgeons to use is a special computer software that would improve patient selection and predict which hips are at risk for failure. This same software will have the ability to measure (and thereby improve) the best place for cup position. Advances have been made just from the fact that when failed implants are removed, the surgeon can examine them for changes that might help explain those failures.
For example, wear patterns and fatigue fractures of cup liners have led to improved materials that hold up better with greater wear resistance. And metal debris found in the removed implants suspected as the cause of inflammation has resulted in the increased use of polyethylene (plastic) and ceramic components.
Several recent studies have also suggested surgeons reconsider when thinking about using a metal-on-metal implant for women young enough to have children. There is evidence that ions associated with metal can cross from the mother to the developing child in utero (inside the womb).
Besides the many concerns and factors just related to the surgical technique and implants, surgeons must also pay attention to pain management, post operative complications, and rehab protocols. The cost of these operations hasn't escaped examination either. Hospital managers agree that economics and cost containment are important if joint replacement surgeries are going to continue to be affordable. And that doesn't even touch the issue of the uninsured Americans who need joint replacements.
In summary, this update on hip replacements focused on five major areas of concern. Results referred to as outcomes are at the top of the list. Implant types, designs, and surface take up the bulk of the discussion. Complications following surgery and even resulting in implant failure are discussed. And finally, economic and management issues are presented. Anyone who wants to keep up with the latest concerns and directions regarding total hip replacements will find this update helpful.
Michael H. Huo, MD, et al. What's New in Total Hip Arthroplasty. In The Journal of Bone and Joint Surgery. December 15, 2010. Vol. 92-A. No. 18.