Best of 2007: Top 5

For this issue, members of the Orthopaedics Today International Editorial Advisory Board selected the most important news stories reported in our publication in 2007. The results were close, but the May/June article on hip resurfacing arthroplasty — and the long learning curve associated with it — garnered the top spot.

Summaries of the Top 5 stories, and a short list of honorable mentions, appear below. To read more about those stories, please log onto www.ORTHOSuperSite.com and do a search using the key phrase listed at the end of each synopsis.

Robert Trace
Managing Editor

1. Learning curve for hip resurfacing longer than expected

Hip resurfacing arthroplasty was a contentious topic among orthopaedists worldwide in 2007, as surgeons debated the merits and shortcomings of the procedure at various meetings. As a result, it earned the top spot in our Top 5 list for 2007.

In one of the key prospective studies on the topic last year, British and Australian researchers identified a longer-than-expected learning curve to accurately perform hip resurfacing arthroplasty.

Orthopaedic surgeons taking part in the study, all of whom had performed more than 1,000 hip surgeries, found they had to complete three times more resurfacing surgeries than they expected in order to place the femoral hip resurfacing components within ±5° of the desired neck/head angle, said Diane L. Back, FRCS, Ed Orth, of London.

The surgeons initially estimated their learning curve to be just 10 to 20 cases, Back told Orthopaedics Today International in the May/June issue. But in reality, “The results showed that it took 55 to 60 cases for most of our surgeons to get the femoral component where they actually planned it.”

Based on her findings, she now advises others to expect their margin of error implanting the femoral resurfacing components to be high for the first few years, no matter how skilled they are.

2. Orthopaedists face growing number of scientific events

Many Editorial Board members and readers commented throughout 2007 on the rapidly increasing number of musculoskeletal medicine meetings and courses offered each year.

John C.Y. Leong, FRCS, MCAS, president of the Open University of Hong Kong and former chairman of the Orthopaedics Today International Editorial Board, said in his March/April editorial that the “abundance of orthopaedic meetings poses several challenges. For the potential participant, there are perhaps several meetings that he or she feels ‘obliged’ to attend, including the annual meeting of their national orthopaedic society and the meetings of his or her selected specialty societies.”

But even attending those events can get expensive and time consuming, and too many meetings can result in duplication of paper presentations. Furthermore, “The amount of [industry] sponsorship has increased throughout the years in response to the high costs across the board,” he wrote. “Consequently, trade exhibitors are finding it increasingly difficult to sponsor four or five similar meetings a year.”

While the increasing specialization within orthopaedic medicine has directly impacted this growth spurt in conferences, combined congresses like Spine Week, which attempt to unite several similar organizations focused on the same specialty, should be a boon for industry and busy clinicians alike in the near future, according to Leong.

3. Ceramic-on-metal hip bearings show less wear

Early clinical and laboratory test results of ceramic-on-metal hip replacements demonstrated decreased wear and friction compared to metal-on-metal hip replacements, according to a British investigation.

In the July/August issue, John M. Fisher, PhD, and colleagues reported that the differential hardness, smoother surfaces, superior lubrication and corrosive wear reduction of ceramic-on-metal (COM) hip replacements resulted in significantly decreased wear and friction compared to metal-on-metal (MOM).

The investigators also found that COM bearings avoid the stripe wear seen with ceramic-on-ceramic (COC) and MOM hip replacements, and “COM bearings reduced wear and metal ion levels by at least 10-fold compared to MOM bearings,” Fisher said.

In addition, “COM bearings … offer greater design flexibility and a reduced risk of component fracture compared to COC bearings,” he said.

Fisher and his colleagues won the Otto Aufranc Award for their presentation at the American Association of Hip and Knee Surgeons Specialty Day meeting.

4. Researchers report similar results with fixed, mobile-bearing TKAs at 13 years

While the theoretical advantages of mobile-bearing knees include less wear and better clinical results than fixed-bearing knees, study findings reported in the July/August issue of Orthopaedics Today International revealed similar clinical and radiographic outcomes at long-term follow-up for both bearing types.

The investigators also discovered no radiographic evidence of osteolysis in either group.

“Although there is no evidence to prove the superiority of the mobile-bearing TKA over the fixed-bearing TKA, the clinical and radiographic results of both types of the TKA were encouraging in long-term follow-up,” Young-Hoo Kim, MD, of Seoul, said at the American Academy of Orthopaedic Surgeons 2007 Annual Meeting.

In their prospective, randomized trial, the Korean investigators studied 146 patients (mean age, 69.8 years) who underwent simultaneous bilateral TKAs with the Low Contact Stress (LCS) Mobile-Bearing Knee System in one knee and the Anatomic Modular Knee (AMK), a fixed-bearing implant, in the other (both implants by DePuy).

A mean follow-up of 13.2 years revealed similar mean Knee Society scores, Hospital for Special Surgery scores, functional scores and activity scores for the LCS and AMK groups.

Kim said these findings could “put to rest” some of the ongoing debate regarding which is more effective: mobile-bearing or fixed-bearing knees.

5. Higher THA revision rate reported with large femoral heads

Researchers from Lithuania reported that larger femoral heads resulted in higher revision rates in a recent long-term study.

This finding, which earned a spot in the Top 5 stories of 2007, contradicts the results of an earlier investigation, which suggested there was no significant difference between the revision rates of 22-mm and 32-mm femoral heads at 12 years.

Orthopaedics Today International reported the new results in the September/October issue.

Investigators studied more than 1,550 patients with osteoarthritis (OA), rheumatoid arthritis and femoral neck fractures who underwent total hip arthroplasty (THA) using the Scan Hip Classic I MitAB stem (MitAB) with either 22-mm or 32-mm femoral heads for up to 21 years. The 1,720 THAs were performed at a single institution between 1983 and 1995.

Using a life table method to determine the revision rate for any component due to aseptic loosening, the researchers found a significantly higher cumulative revision rate with 32-mm heads (P=.04), which could be due to polyethylene particles.

“In larger-diameter femoral heads, we have thicker polyethylene, and it’s also known that thickness of polyethylene inversely correlates with wear,” Sarunas Tarasevicius, MD, said during his presentation at the 8th European Federation of National Associations of Orthopaedics and Traumatology Congress.