AAOS Now

Published 2/1/2010
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Mary Ann Porucznik

How do your practices compare to others?

AAHKS symposium provides information on how members practice

For nearly half an hour, Daniel J. Berry, MD, asked questions. The audience—members of the American Association of Hip and Knee Surgeons—used a touchpad audience response system to answer. The result was an informative look at how orthopaedic surgeons practice hip and knee arthroplasty.

“By my calculations, this might be the largest poll ever taken of orthopaedic surgeons on these questions,” noted Dr. Berry, who also pointed out that “the majority answer is not necessarily the correct one; surgeons need to individualize treatment to patients. It’s just an opportunity to compare what you do with what everybody else in the room does.”

Performing THA
One series of questions focused on performing total hip arthroplasty (THA)—from the selection of anesthetic to postsurgical activity recommendations. Nearly half of respon- dents identified a spinal anesthetic as their favorite choice for surgery, although a quarter of respondents liked using a general anesthetic. The rest of the audience used some form of combined anesthesia (general and epidural, general and psoas block, or spinal and psoas block).

Nearly two thirds of respondents selected a posterior approach as their favorite for primary THA. But one in five liked an anterolateral approach, and one in ten performed a direct anterior approach. A two-incision procedure was used by less than 5 percent of respondents.

When asked about blood management practices, nearly three quarters of respondents (73 percent) said they never ask primary THA patients to donate autologous blood, which Dr. Berry thought represented a significant shift from 5 years ago. He also noted a big change with the use of drains after THA; more than half of respondents (54 percent) no longer use drains.

Although one in five respondents is using aspirin (with or without mechanical compression devices) as a prophylaxis for deep venous thrombosis (DVT) after THA, a third of the audience responded that they use low-molecular-weight heparin (with or without mechanical support), and nearly 40 percent use warfarin (with or without mechanical support).

Nearly 90 percent of respondents reported allowing full weight bearing as tolerated immediately after surgery, and a similar percentage counsel patients to be careful in their choice of activities after joint replacement.

THA implant
A second series of questions focused on the selection and implantation of the prostheses. Nearly half of respondents (48 percent) reporting using a press-fit hemisphere with no augmentation most of the time for primary THA, and the remainder reported using a press-fit hemisphere with either screws (44 percent) or spikes and fins (7 percent). “If that’s correct,” noted Dr. Berry, “nobody in this audience is cementing cups on a routine basis.”

Most audience members were also using uncemented femoral implants most of the time. Nearly half the respondents (47 percent) reported using uncemented stems all the time, and the same percentage was using uncemented stems at least three quarters of the time. “This represents a remarkable shift in practice,” said Dr. Berry.

A follow-up question was an attempt to identify the type of stem being used in uncemented THA. More than half of respondents (55 percent) reported using a wedge stem, tapered in several planes, while more than a third (38 percent) responded that they use a tapered, parallel-sided implant.

The issue of bearing surfaces was also covered. About one in five respondents (18 percent) reported using polyethylene exclusively; 44 percent used polyethylene or metal-metal bearings; and about a quarter of the audience (24 percent) reported using polyethylene, ceramic-ceramic, or metal-metal, depending on the circumstances.

Dr. Berry also attempted to address the question of femoral head size. With a cup of 56 mm or larger, he asked, what size femoral head would you personally prefer to use? More than half the respondents (53 percent) selected a head size of 36 mm; more than a quarter (27 percent) opted for a 40 mm or larger femoral head.

Performing TKA
Switching to total knee arthroplasty (TKA), Dr. Berry repeated several of the general questions, discovering that nearly a quarter (24 percent) of the audience responding used a spinal anesthetic only for TKA, and more than half used a femoral nerve block in conjunction with another anesthetic (spinal, general, or epidural).

Similarly, when asked about blood management, 85 percent of respondents said they never ask patients for autologous blood for primary, unilateral TKA. “Clearly,” said Dr. Berry, “most people are no longer collecting autologous blood for either hip or knee.”

Most people are, however, using a tourniquet when performing TKA. Nearly all (95 percent) respondents report that they always or almost always use a tourniquet. The most popular operative approach was the median parapatellar (71 percent), followed by the midvastus (23 percent), and the subvastus (7 percent).

Postsurgical treatment for TKA routinely involves continuous passive motion (59 percent) and drains (66 percent). Almost no difference was found in DVT prophylaxis after TKA when compared to THA; warfarin (with or without mechanical support) was the most popular prophylaxis, followed by low-molecular-weight heparin and aspirin. Similarly, most respondents (95 percent) counsel patients to avoid certain activities after arthroplasty.

TKA implants
Recognizing the need for individualization for patients, Dr. Berry asked several questions about implant selection in TKA. The audience was split on the choice of cruciate-retaining (40 percent) and posterior-stabilizing (60 percent) implant design for a standard TKA, but in a complex case, 90 percent of respondents reported using the posterior-stabilizing design. In stark contrast to THA fixation, more than 80 percent of respondents reported using cemented components all the time in TKA, with only 10 percent of respondents using hybrid fixation (uncemented femur and cemented tibial components).

More than 80 percent of respondents reported regularly using a modular, fixed-bearing, metal-backed tibial implant. Almost half (46 percent) reported using a mobile-bearing implant occasionally, and 22 percent reported using a metal-backed, non-modular implant on an occasional basis.

More than a third (34 percent) of the audience reported using conventional polyethylene all the time, with the remainder using a cross-linked polyethylene surface at least some of the time.

Nearly 8 out of 10 (78 percent) of respondents always perform patellar resurfacing with TKA, which Dr. Berry called a“strong North American preference.” The use of antibiotic cement was also strong, with 37 percent of respondents reporting that they used it “always” in routine primary TKA, and 45 percent of respondents saying that they used it in high-risk patients.

Approximately 15 percent of respondents strongly believe in computer navigation, using it in almost all cases, but 58 percent of audience members never use it.

Dr. Berry disclosed the following ties to industry: DePuy.

Mary Ann Porucznik is managing editor of AAOS Now. She can be reached at porucznik@aaos.org

Identifying problems
In an attempt to identify the frequency of occurrence of problems associated with total hip arthroplasty, Dr. Berry asked audience members to respond to a series of questions about their personal experience with these problems resulting in revision surgery. Each question began, “Have you personally ever revised a patient for…?”