Study: THA, TKA, and the risk of AMI
A Danish study published online in Archives of Internal Medicine (July 23) finds that the risk of acute myocardial infarction (AMI) is substantially increased in the first 2 weeks following total hip arthroplasty (THA) and total knee arthroplasty (TKA). The retrospective, nationwide cohort study of 95,227 patients who underwent THA or TKA between Jan. 1, 1998, and Dec. 31, 2007, matched each patient to three controls based on age, sex, and geographic region. During the first 2 weeks postoperative, the risk of AMI was increased 25-fold in THA patients compared with controls, and 31-fold for TKA patients compared to controls. For 2 to 6 weeks after surgery, risk of AMI remained elevated for THA patients, but not for TKA patients. Absolute 6-week risk of AMI was 0.51 percent in THA patients and 0.21 percent in TKA patients.

Study: Controlled hypotension during shoulder arthroscopy
A study published in the Journal of Bone & Joint Surgery—American (July 18) examines the safety of controlled hypotension during arthroscopic shoulder procedures with the patient in the beach-chair position. The prospective study of 52 consecutive patients found that all patients violated at least one recommended limit for blood pressure reduction, but no adverse neurologic sequelae were observed in any patient on the basis of the Mini-Mental State Examination.

Study: Radiographic changes clue to OA development
Data from a United Kingdom study published in Arthritis & Rheumatism (July) suggest that progression of knee osteoarthritis (OA) is common when radiographic changes in the joint are present. The blinded, prospective study of 561 women found that 13.7 percent of the participants had radiographic knee OA in at least one knee at baseline, with the prevalence increasing to 47.8 percent by year 15. Participants with a Kellgren/Lawrence grade of 1 at baseline were more likely to experience worsening by year 15, compared with participants who had a baseline grade of 0.

Study: MRI use in Achilles tendon rupture diagnosis
Data from a study in Clinical Orthopaedics and Related Research (CORR) (August) suggest that use of magnetic resonance imaging (MRI) to document Achilles tendon rupture is time-consuming, expensive, and can lead to treatment delays. The retrospective review compared 66 patients with surgically confirmed acute Achilles ruptures and preoperative MRI to a control group of 66 patients without preoperative MRI. All patients had all three clinical findings (abnormal Thompson test, decreased resting tension, and palpable defect) preoperatively and complete ruptures intraoperatively. It took a mean of 5.1 days to obtain MRI after the injury; patients waited 8.8 days for initial evaluation and 12.4 days for surgical intervention. In the control group, initial evaluation occurred at 2.5 days and surgical intervention at 5.6 days after injury.

These items originally appeared in AAOS Headline News Now, a thrice-weekly enewsletter that keeps AAOS members up to date on clinical, socioeconomic, and political issues, with links to more detailed information. Subscribe at www.aaos.org/news/news.asp (member login required)