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AAOS Now

Published 2/1/2010

Second Look – Clinical News and Views

If you missed these Headline News Now items the first time around, AAOS Now gives you a second chance to review them. Headline News Now—the AAOS thrice-weekly, online update of news of interest to orthopaedic surgeons— brings you the latest on clinical, socioeconomic, and political issues, as well as important announcements from AAOS.

Studies find greater risk in CT scans
Two studies published in the Archives of Internal Medicine (Dec. 14/28, 2009) point toward an increase in estimated risk to patients from computed tomography (CT) scans. A retrospective cross-sectional study of radiation doses associated with the 11 most common types of diagnostic CT studies found that the overall median effective doses were higher and more variable than generally quoted.

Effective doses also varied significantly within and across institutions, with a mean 13-fold variation between the highest and lowest dose for each study type.

The second study estimated age-specific cancer risks based on current CT scan use in the United States according to age, sex, and scan type. Approximately 29,000 future cancers could be related to CT scans performed in the United States in 2007; one-third of the projected cancers were due to scans performed at the ages of 35 to 54 years compared with 15 percent due to scans performed at ages younger than 18 years.

COX-2 inhibitors and low-dose aspirin
A study published online in the Proceedings of the National Academy of Sciences finds that celecoxib and other COX-2 inhibitors may interfere with the cardioprotective benefits of taking low dosages of aspirin. Celecoxib and other coxibs bind tightly to a subunit of COX-1, which mediates thrombosis. Although celecoxib binding to one monomer of COX-1 did not affect the normal catalytic processing of arachidonic acid by the second partner subunit, celecoxib did interfere with the inhibition of COX-1 by aspirin in vitro. Individuals taking both a COX-2 low-dose aspirin should take them at least a half-hour apart (aspirin first).

Reducing healthcare-associated infections
Two studies published in the New England Journal of Medicine (NEJM) (Jan. 7, 2010) suggest relatively simple methods to prevent some healthcare-associated infections. One study found that preoperative cleansing of the patient’s skin with chlorhexidine–alcohol is superior to cleansing with povidone–iodine for preventing surgical-site infection after clean-contaminated surgery. The second study found that rapid screening and decolonizing of nasal carriers can reduce the number of surgical-site Staphylococcus aureus infections. The effect of antibacterial treatment was most pronounced for deep surgical-site infections.

Take calcium, vitamin D together to reduce fractures
A review of data from seven randomized trials published in the British Medical Journal (Jan. 12, 2010) finds that vitamin D given alone in doses of 10 µg or 20 µg is not effective in preventing fractures, but calcium and vitamin D given together can do so, irrespective of age, sex, or previous fractures. Trials using vitamin D with calcium showed a reduced overall risk of fracture and hip fracture. They found no significant effects for patients given vitamin D alone in daily doses of 10 µg or 20 µg, and no interaction between fracture history and treatment response, nor any interaction with age, sex, or hormone replacement therapy.

Dabigatran similar to warfarin for patients with acute VTE
According to a study in NEJM (Dec. 10, 2009), dabigatran has similar safety and efficacy to warfarin in the treatment of acute venous thromboembolism (VTE). A randomized, double-blind, noninferiority trial of 2,539 patients randomly assigned to receive either 150 mg dabigatran twice daily or warfarin, dose-adjusted to achieve an international normalized ratio of 2.0 to 3.0 found that 30 patients (2.4 percent) in the dabigatran group had recurrent VTE, compared to 20 patients (2.1 percent) in the warfarin group—a risk differential of 0.4 percentage points. Major bleeding episodes occurred in 20 patients (1.6 percent) assigned to dabigatran and in 24 patients (1.9 percent) assigned to warfarin; episodes of any bleeding were observed in 205 patients (16.1 percent) assigned to dabigatran and 277 patients (21.9 percent) assigned to warfarin. The number of deaths, acute coronary syndromes, and abnormal liver-function tests were similar in the two groups.

Fist method estimates blood loss more accurately
According to a study in the November 2009 American Journal of Emergency Medicine, physicians and emergency workers can use a simple method based on the size of a human fist to estimate blood loss in a trauma situation. Increments of human whole blood were measured and fist size compared to surface area of blood present; one fist covers a surface area corresponding to 20 mL of blood. Asked to estimate the size of two pools of blood, 74 participants reduced their average error from the mean by 76 percent (p<0.0001) for the smaller volume and by 40 percent (>p<0.0001) for the larger volume of blood after learning the method.>

Strength training can help OA knee patients
According to a study in Arthritis Care & Research (January 2010), sedentary, middle-aged patients with mild, early knee osteoarthritis (OA) may benefit from strength training, self-management, or a combination of the two. A 24-month randomized intervention trial at a single academic medical center involved 201 adults aged 35–64 years with knee OA, pain, and self-reported physical disability. Patients were randomized to receive strength training, self-management, or a combined program. Although overall compliance was modest, all groups showed a significant increase from pre- to post-treatment in all physical functioning measures, including leg press, range of motion, work capacity, balance, and stair climbing, as well as decreased self-reported pain and disability.

Artificial clotting factor in trauma situations
According to a study in Science Translational Medicine (Dec. 16, 2009), synthetic platelets based on Arg-Gly-Asp functionalized nanoparticles may someday be used in the field to stanch the flow of bleeding in trauma patients. The synthetic platelets cut bleeding time in half in rat simulations of major trauma and were more effective than other treatments, including recombinant factor VIIa, which is used clinically for uncontrolled bleeding.

Tylenol recall expanded
The U.S. Food and Drug Administration states that McNeil Consumer Healthcare is expanding a voluntary recall to include all available product lots of Tylenol Arthritis Pain Caplet 100-count bottles with a distinctive red EZ-OPEN cap. Consumers who purchased Tylenol Arthritis Pain Caplet 100-count red-cap bottles from the lots included in this recall should stop using the product and contact McNeil for instructions regarding a refund or replacement.

Anemia patients at increased risk for hip fracture
A British study published online in Gastroenterology finds that patients diagnosed with pernicious anemia (PA) are at increased risk for hip fracture, even after vitamin B12 therapy. The retrospective cohort study of 9,506 patients with a diagnosis of PA who were undergoing B12 injection therapy and 38,024 matched controls Found that patients with PA had a greater risk of hip fracture than the controls (HR 1.74, 95 percent confidence interval [CI] 1.45-2.08).