Medical Studies

March 2008

SAN FRANCISCO -  A study indicates that having a metal-on-metal bearing surface and performing high-impact activities preoperatively may be positive predictors for participating in high-impact sports after total hip arthroplasty.

To determine which patients would participate in high-impact sports activity following total hip arthroplasty (THA) and to examine the factors linked to participation in these sports, David R. Marker, BS, and colleagues submitted pre- and postoperative questionnaires to 303 THA patients who had a mean follow-up of 3 years.

The investigators found that 30% of patients participated in at least one or more high-impact sport postoperatively for an average of 4.3 hours per week.

A regression analysis revealed that a preoperative high activity level and metal-on-metal bearing surface were the only statistically significant factors to predict participation in high-impact sports postoperatively. Moreover, while a comparison of patients participating in high- and low-impact sports revealed similar preoperative Harris Hip Scores, the investigators discovered that the high-impact sport participating patients had higher postop Harris Hip Scores.

"There are many patients participating in these high-impact sports, up to 30% in our cohort," Marker said during his presentation at the American Academy of Orthopaedic Surgeons 75th Annual Meeting, held here. "The preoperative participation, as well as the metal bearing surface, were found to be predictive of postoperative participation. We found [in] the short-term follow-up that the high-impact sports patients had similar and better outcomes."

For more information:

Marker DR, Seyler TM, Ulrich SD, et al. High-impact sports after THA: Is the bearing type and independent predictor of activity level? Paper #16. Presented at the American Academy of Orthopaedic Surgeons 75th Annual Meeting. March 5-9, 2008. San Francisco.

April 2008

Using potent anticoagulants such as low-molecular-weight heparin to prevent pulmonary embolism in total hip or knee arthroplasty patients, as recommended by the Chest Physicians Consensus Statement, may actually increase the risk of all-cause mortality compared to multimodal prophylaxis measures, according to a systematic literature review published in Clinical Orthopaedics and Related Research.

"We believe the American College of Chest Physicians should reconsider their guidelines to reflect the fact that PE (pulmonary embolism) occurs despite the use of potent anticoagulants and may, in fact, expose patients to increased mortality after surgery," the authors said in the study.

Nigel E. Sharrock, BMedSci, MB, ChB, and colleagues at the Hospital for Special Surgery, New York, conducted the systematic review, which included 20 English language studies published during the last 9 years. The researchers focused on studies that involved patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) and divided publications into three categories based on the venous thromboembolism prophylaxis regimen.

Specifically, Group A included the use of low-molecular-weight heparin, ximelagatran, fondaparinux or rivaroxaban, Group B included the use of a multimodal prophylaxis, and Group C included the use of warfarin.

"Multimodal prophylaxis (Group B) was defined as a protocol consisting of intention to use regional anesthesia (epidural or spinal) with or without intraoperative heparin during surgery or pneumatic compression and aspirin after surgery," the study authors noted.

The researchers found that the lowest number of deaths occurred among patients in Group B. Patients in Groups A and C were more than two times as likely to die compared to those in Group B, with no significant difference between Group A and Group C.

Patients in Group A also had a 60% to 70% higher risk of nonfatal PE compared to patients in Group B.

Nonfatal PE occurred in 94 of 15,839 patients in Group A (0.6%) vs. 25 of 7,193 patients in Group B (0.35%), according to the study.

"We show clinical PE occurs despite the use of powerful anticoagulants. The rate of 0.6% is comparable to the rate of 1% previously described with warfarin and low-molecular-weight heparin in cohort studies.

"This literature cannot support the use of powerful anticoagulants to prevent PE, although they clearly reduce the risk of venographically evident deep vein thrombosis," the study authors wrote.

For more information:

Sharrock NE, Gonzalez Della Valle A, Go G, et al. Potent anticoagulants are associated with a higher all-cause mortality rate after hip and knee arthroplasty. Clin Orthop Relat Res. 2008;466:714-721.