Medical Studies

Study: Surface replacement arthroplasty may offer advantages over THA

Canadian investigators said hip resurfacing resulted in greater patient activity after 2 years.

By Robert Trace
1st on the web (September 19, 2007)
September 2007

SEOUL — Total hip arthroplasty is an established procedure with well-documented complication rates and clinical results, but surface replacement arthroplasty may offer additional clinical benefits to many patients, according to a group of Canadian researchers.

"We decided in 2003 to do a comparative study of hip resurfacing, or surface replacement arthroplasty (SRA), to the gold standard of total hip arthroplasty (THA), since we were not aware of any direct prospective studies out there comparing the two procedures," said Pascal-André Venditolli, MD, of the Maisonneuve-Rosemont Hospital in Quebec.

He and his colleagues randomly assigned 210 hips to receive uncemented metal-on-metal THA (103 hips) or a hybrid metal-on-metal SRA (107 hips). All surgeries were performed by three orthopedic surgeons, who used a posterior approach.

The researchers prospectively collected perioperative and postoperative data, and analyzed the clinical data for a minimum of 2 years.

Postop complications included three isolated traumatic dislocations and one recurrent dislocation in the THA group, which required acetabular cup revision. Two SRAs required revision for late head collapse. No postop femoral neck fractures occurred in the SRA group, he said.

There was one case of loosening at 6 months postop in the resurfacing group, which had shifted varus. There were also two cases of deep venous thrombosis in both patient groups, he said.

Although the investigators did not report a significant difference in surgical time between the two procedures, patients' length of stay in the hospital was significantly shorter for the SRA group compared to the THA patients — 5 days vs. 6.1 days for the THA group (P=.001).

"There was also a significant difference in return to work: 96% of the SRA patients returned to their previous work within 1 year vs. 83% in the THA group," Venditolli said.

Although patients in both groups demonstrated a high satisfaction rate and achieved similar WOMAC and Merle d'Aubigné functional scores, "SRA patients had better UCLA activity scores (7.1 vs. 6.3; P=.037) and returned to heavier activities (P=.035)" after 2 years, he said.

"This randomized study shows that SRA and THA present a similar complication rate, but distinctive complications," Venditolli said. "It also suggests that SRA results in better function and improved patient activity in comparison to THA.

"However, the effect of long-term fixation related to increased activity levels is unknown. Long-term follow-up is necessary to determine the survivorship of SRA over THA," he said.

For more information:

Vendittoli P-A, Lavigne M, Lusignan D, Roy A-G. A randomized study comparing surface replacement arthroplasty to total hip arthroplasty: 2-4 years follow-up. F028-2. Presented at the 15th Triennial Congress of the Asia Pacific Orthopaedic Association. Sept. 9-13, 2007. Seoul.

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Estimates of Healthcare-Associated Infections

CDC strives to understand how healthcare-associated infections happen and to develop appropriate interventions. A new report from CDC updates previous estimates of healthcare-associated infections. In American hospitals alone, healthcare-associated infections account for an estimated 1.7 million infections and 99,000 associated deaths each year. Of these infections:

• 32 percent of all healthcare-associated infection are urinary tract infections
• 22 percent are surgical site infections
• 15 percent are pneumonia (lung infections)
• 14 percent are bloodstream infections

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2007-09-19 22:47:00

Nanotechnology diamond ice coatings could improve knee prostheses and solar cells

There is a huge demand for medical implants for almost every body part you can think of. As we have reported here before, the market for medical implant devices in the U.S. alone is estimated to be $23 billion per year and it is expected to grow by about 10% annually for the next few years. Implantable cardioverter defibrillators, cardiac resynchronization therapy devices, pacemakers, tissue and spinal orthopedic implants, hip replacements, phakic intraocular lenses and cosmetic implants will be among the top sellers. Current medical implants, such as orthopedic implants and heart valves, are made of titanium and stainless steel alloys, primarily because they are biocompatible. Unfortunately, in many cases these metal alloys with a life span of 10-15 years may wear out within the lifetime of the patient. With recent advances in industrial synthesis of diamond and diamond-like carbon film bringing prices down significantly, researchers are increasingly experimenting with diamond coatings for medical implants. On the upside, the wear resistance of diamond is dramatically superior to titanium and stainless steel. On the downside, because it attracts coagulating proteins, its blood clotting response is slightly worse than these materials and the possibility has been raised that nanostructured surface features of diamond might abrade tissue. That's not something you necessarily want to have in your artificial knee or hip joints (although some of the currently used implant materials cause problems as well). Researchers have now run simulations that show that thin layers of ice could persist on specially treated diamond coatings at temperatures well above body temperature. The soft and hydrophilic ice multilayers might enable diamond-coated medical devices that reduce abrasion and are highly resistant to protein absorption.

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Study: Surface replacement arthroplasty may offer advantages over THA

Canadian investigators said hip resurfacing resulted in greater patient activity after 2 years.

By Robert Trace
1st on the web (September 19, 2007)
September 2007

SEOUL — Total hip arthroplasty is an established procedure with well-documented complication rates and clinical results, but surface replacement arthroplasty may offer additional clinical benefits to many patients, according to a group of Canadian researchers.

"We decided in 2003 to do a comparative study of hip resurfacing, or surface replacement arthroplasty (SRA), to the gold standard of total hip arthroplasty (THA), since we were not aware of any direct prospective studies out there comparing the two procedures," said Pascal-André Venditolli, MD, of the Maisonneuve-Rosemont Hospital in Quebec.

He and his colleagues randomly assigned 210 hips to receive uncemented metal-on-metal THA (103 hips) or a hybrid metal-on-metal SRA (107 hips). All surgeries were performed by three orthopedic surgeons, who used a posterior approach.

The researchers prospectively collected perioperative and postoperative data, and analyzed the clinical data for a minimum of 2 years.

Postop complications included three isolated traumatic dislocations and one recurrent dislocation in the THA group, which required acetabular cup revision. Two SRAs required revision for late head collapse. No postop femoral neck fractures occurred in the SRA group, he said.

There was one case of loosening at 6 months postop in the resurfacing group, which had shifted varus. There were also two cases of deep venous thrombosis in both patient groups, he said.

Although the investigators did not report a significant difference in surgical time between the two procedures, patients' length of stay in the hospital was significantly shorter for the SRA group compared to the THA patients — 5 days vs. 6.1 days for the THA group (P=.001).

"There was also a significant difference in return to work: 96% of the SRA patients returned to their previous work within 1 year vs. 83% in the THA group," Venditolli said.

Although patients in both groups demonstrated a high satisfaction rate and achieved similar WOMAC and Merle d'Aubigné functional scores, "SRA patients had better UCLA activity scores (7.1 vs. 6.3; P=.037) and returned to heavier activities (P=.035)" after 2 years, he said.

"This randomized study shows that SRA and THA present a similar complication rate, but distinctive complications," Venditolli said. "It also suggests that SRA results in better function and improved patient activity in comparison to THA.

"However, the effect of long-term fixation related to increased activity levels is unknown. Long-term follow-up is necessary to determine the survivorship of SRA over THA," he said.

For more information:

Vendittoli P-A, Lavigne M, Lusignan D, Roy A-G. A randomized study comparing surface replacement arthroplasty to total hip arthroplasty: 2-4 years follow-up. F028-2. Presented at the 15th Triennial Congress of the Asia Pacific Orthopaedic Association. Sept. 9-13, 2007. Seoul.

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Study results outline dabigatran etexilate as potential thromboprophylaxis therapy for patients undergoing total hip replacement surgery

 

RIDGEFIELD, Conn., Sept. 13 /PRNewswire/ -- Boehringer Ingelheim today announced that the September 15 issue of The Lancet will publish results from the RE-NOVATE study, which investigated dabigatran etexilate as a potential therapy for patients undergoing total hip replacement surgery(1). The results from this study demonstrate that both doses (220mg and 150mg) of the oral direct thrombin inhibitor, dabigatran etexilate, administered for a median of 33 days, were non-inferior to injectable enoxaparin in reducing the risk of venous thromboembolism (VTE) after total hip replacement surgery with similar safety.

 

The primary endpoint of this trial was a composite consisting of total venous thromboembolic events and all-cause mortality during treatment, which occurred in 6.0% of the 220mg group and 8.6% of the 150mg group taking dabigatran etexilate, versus 6.7% of the enoxaparin group. Importantly, a pre-specified secondary outcome of major venous thromboembolism and venous thromboembolism-related mortality was also similar between groups, occurring in 3.1% of the 220mg group and 4.3% of the 150mg group taking dabigatran etexilate, versus 3.9% of the enoxaparin group.

 

Anticoagulation-related bleeding is the primary safety concern during hip replacement surgery, since major bleeding into the replaced joint can have a detrimental impact on clinical outcome(2). Generally, few major bleeding events were reported, occurring at 2.0% in the 220mg group and 1.3% in the 150mg group for dabigatran etexilate, versus 1.6% in the enoxaparin group. Notably about half of all major bleeding events started after surgery and before the first dose of dabigatran etexilate. There were no major bleeding events reported after hospital discharge in the dabigatran etexilate groups.

 

Data from frequent liver function monitoring showed that the frequency of increases in liver enzyme concentrations with dabigatran etexilate is low during the entire extended treatment period. Results showed that alanine aminotransferase (ALT) elevation greater than three times the upper limit of normal occurred in 5.3% enoxaparin group, as compared to 3.0% in the 150mg group and 3.0% in the 220mg group taking dabigatran etexilate. Similarly, the incidence of acute coronary events was low, with no significant differences between all groups.

 

Current treatment guidelines recommend that patients undergoing knee or hip replacement surgery receive thromboprophylaxis (treatment to prevent VTE) with low molecular weight heparin (LMWH), fondaparinux or warfarin for at least 10 days after surgery. For patients undergoing hip replacement surgery, extended thromboprophylaxis for up to 28-35 days is recommended.(3) The RE- NOVATE study was designed consistent with these guidelines.

 

About dabigatran etexilate

 

Dabigatran etexilate is an investigational oral direct thrombin inhibitor that specifically and reversibly inhibits thrombin, the key enzyme for blood clot formation, and is currently in phase 3 development. In the RE-NOVATE study, dabigatran etexilate was dosed once a day without routine coagulation monitoring. Patients in the study received a fixed dose of dabigatran etexilate and were not titrated during the duration of the study.

 

Further studies investigating dabigatran etexilate

 

Dabigatran etexilate is being investigated in multiple phase 3 trials that are designed to investigate the oral direct thrombin inhibitor as a potential treatment and prophylaxis for several thromboembolic disease conditions. The phase 3 clinical trial program is expected to involve more than 27,000 patients from Asia, Australia, Europe, the Americas, and South Africa.

 

Boehringer Ingelheim Pharmaceuticals, Inc.

 

Boehringer Ingelheim Pharmaceuticals, Inc., based in Ridgefield, CT, is the largest U.S. subsidiary of Boehringer Ingelheim Corporation (Ridgefield, CT) and a member of the Boehringer Ingelheim group of companies.

 

The Boehringer Ingelheim group is one of the world's 20 leading pharmaceutical companies. Headquartered in Ingelheim, Germany, it operates globally with 137 affiliates in 47 countries and approximately 38,400 employees. Since it was founded in 1885, the family-owned company has been committed to researching, developing, manufacturing and marketing novel products of high therapeutic value for human and veterinary medicine.

 

In 2006, Boehringer Ingelheim posted net sales of US $13.3 billion (10.6 billion euro) while spending approximately one-fifth of net sales in its largest business segment, Prescription Medicines, on research and development. For more information, please visit http://us.boehringer-ingelheim.com.

 

References
1. Lancet ref
2. Lotke PA, Lonner JH. Deep venous thrombosis prophylaxis: better living through chemistry-in opposition. J Arthroplasty 2005;20:15-7
3. Geerts WH, Pineo GF, Heit JA et al. Prevention of Venous Thromboembolism: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004;126:338-400

Web site: http://us.boehringer-ingelheim.com/

 

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Metal ion levels in a triathlete with a metal-on-metal resurfacing arthroplasty of the hip

 

R. De Haan, MD, Orthopaedic Resident¹; P. Campbell, PhD, Research Scientist, Associate Professor²; S. Reid, MD, PhD, Sports Medicine Physician³; A. K. Skipor, MS, Research Scientist⁴; and K. De Smet, MD, Orthopaedic Surgeon¹

1 ANCA Medical Center, Krijgslaan 181, 9000 Gent, Belgium.
2 J Vernon Luck Snr MD, Orthopaedic Research Center, Orthopaedic Hospital, 2400 S., Flower Street, UCLA, Los Angeles 90007, California, USA.
3 St. Helen’s Private Hospital, 186, Macquarie Street, Hobart, Tasmania 7000, Australia.
4 Department of Orthopaedic Surgery, Rush Presbyterian St Luke’s, Medical Center, Room 756, Cohn Research Building, 1735 West Harrison Street, Chicago, Illinois 60612-3833, USA.

 

A prospective study of serum and urinary ion levels was undertaken in a triathlete who had undergone a metal-on-metal resurfacing arthroplasty of the hip four years previously. The one month study period included the final two weeks of training, the day of the triathlon, and the two weeks immediately post-race. Serum cobalt and chromium levels did not vary significantly throughout this period, including levels recorded on the day after the 11-hour triathlon. Urinary excretion of chromium increased immediately after the race and had returned to pre-race levels six days later. The clinical implications are discussed.

 

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Researchers Find Better Way to Deliver Blood Thinner

FRIDAY, Sept. 7 (HealthDay News) -- A new gene-based dosing formula for the anti-clotting drug warfarin should make it easier to prescribe the correct dose of the blood thinner, researchers say.

Up to this point, doctors have had to engage in a trial-and-error process over several weeks that left patients at risk of hemorrhaging from low doses or developing blood clots with too-high doses.

"We already knew these genes affected warfarin dosing, but we didn't know how to use that information clinically," researcher Dr. Brian Gage, medical director of Barnes-Jewish Hospital's Blood Thinner Clinic, said in a prepared statement. "But with this study, we've established a simple way to combine these genetic factors with clinical factors in a dosing algorithm."

Gage and colleagues developed the formula based on study participants who had undergone hip replacement or knee surgery. The study team focused on two genes, VKORC1 and CYP2C9, which are known to affect the way warfarin operates inside the body.

Using the new method, physicians head to a Web-based tool to calculate a patient's initial dosage more accurately...
 

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