By Elizabeth Hofheinz, M.P.H., M.Ed., September 12, 2019
“If you look at the number of hip and knee revisions we do in this country and examine why they need to be done, then you will see that more than half of them are completely preventable,” says one high-volume hip and knee surgeon. “Had the initial surgeries been done properly the second procedures would have been completely unnecessary.”
“The literature indicates that the most prevalent reasons for revisions are dislocations, infections, and fractures. And while you can’t do much to get below that national average of 1% infection rate, the other issues can be addressed through the proper use of technology, robotics, or just putting the parts in more carefully.”
The problem is certainly multi-factorial, but in many cases, says this surgeon, it has to do with decision making. Most of the time, the risky situations are obvious when reviewing the preoperative x-rays. Other times, it’s a gap in knowledge in the profession. New research has shown that a stiff spine is a risk factor for dislocation of a hip replacement, however, it is not clear how to address the situation and it takes time for this new knowledge to be desimminated to the community. It also takes years to prove whether making a change actually makes a difference in the outcomes.
A new potential problem in hip replacement related to dislocation is the use of dual mobility implants. “Many surgeons rely on the dual mobility implant as a ‘bail out’ to prevent a dislocation, thinking that they can use it on every patient. However, this potentially opens the patient to new risks associated with these newer style implants. They should be used appropriately in appropriate patients that actually need them, not in everybody, where the benefits outweight the risks.
On other occasions the issue is the choice of implant for the femur. “Most orthopedic surgeons are only trained on one implant, often times feeling a loyalty to the related company. However, the fact is that some bones cannot accommodate some particular implants. You might argue that if a surgeon trained solely on one device and then switches to another, then that is even more dangerous. But it’s important that we train surgeons on various styles of hip implants so that they can choose appropriately based on the patient. Younger patients have thick bones, and an implant can get stuck in there where it wasn’t designed to be, and loosens easily. For those patients, the surgeon needed to choose a different implant.”
“Not only loosening, but another problem is perioprosthetic fracture, an increasing cause of early failure of hip replacement, especially in women over 75 who are osteoporotic. If you don’t use cement, then there is a higher perioprosthetic fracture rate. In the past 20 years, U.S. surgeons have moved away from cement, but we are now seeing a slow shift back to using cement, especially in older females with osteoporotic bone.”
“Alternatively, some surgeons don’t account for a patient’s tight bone where the stem doesn’t quite fit on the distal part—a Dorr Type A femur. Some of those cases need a ‘ream and broach’ stem instead of blade stem to prevent both early loosening, thigh pain, and periprosthetic fracture.”
But there are many surgeons who just don’t know what to do. “Frankly, there are surgeons that—even if they do get the preoperative x-rays or add extra x-rays to look at the hip-spine relationship—they don’t know what to do with that information.”
His advice? “Go back to basics. Simple templating can pick up risk factors. It is really incredibly predictable who will have trouble…and it’s up to the surgeon to modify his or his choice of implants and/or procedure.”
