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Knee dislocations require routine arteriography, study shows.

Chicago -- Physical examination of the multidislocated knee is inadequate for determining the need for arteriography, according to a University of Michigan study.

"Routine arteriography is justified in multiligament injuries to the knee by the high incidence of popliteal artery injury, given the potentially devastating consequences of a delay in diagnosis and the relatively low morbidity of an arteriograph," Dr. E. Barry McDonough told the annual meeting of the American Academy of Orthopaedic Surgeons.

Knee dislocation is rising in incidence due to increasing participation in sports, the popularity of all-terrain vehicles, and the boom in obesity, said Dr. McDonough, who is now with a group practice in Glen Ellyn, Ill.

Whereas anterior dislocations can be the result of a hyperextension injury, posterior dislocations may be the result of motor vehicle dashboard injury to the flexed knee. The frequent result of dislocation trauma is a damaged popliteal artery, said Dr. McDonough.

Determining the vascular status of a limb is imperative, he added. The amputation rate if repair occurs within 8 hours is 11%; otherwise, the amputation rate skyrockets to 86%, he said.

Between December 1993 and January 2005, Dr. McDonough and Dr. Edward M. Wojtys, professor of orthopaedic surgery at the University of Michigan, Ann Arbor, conducted a retrospective study of patients diagnosed with multiligamentous injury of the knee requiring surgical reconstruction. They identified 72 knees in 71 patients; there were 12 vascular injuries among nine men and three women. The causes were motor vehicle accidents (three cases); falls (four cases); sports (two cases); and assault, boating, and being pinned by a vehicle (one case each).

Physical exam and MRI were used to determine which ligaments were damaged, and these were confirmed at the time of surgical reconstruction. A total of four patients with vascular injury had abnormal physical exams on initial presentation and underwent emergent revascularization; eight patients had normal physical exams and normal pulses on initial exam.

Of those patients with normal initial physical exams, five were found to have intimal injury, and four underwent vascular bypass. Of three patients with both normal physical exams and normal arteriograms, two were found to have thrombosis secondary to large intimal flap lesions after ligament reconstruction. The remaining patients went on to have a pseudoaneurism requiring vascular reconstruction, said Dr. McDonough.

Dr. McDonough's Findings contradict a recent study, which concluded that routine arteriography is not warranted in the treatment of these injuries, based on physical examination (J. Bone Joint Surg. Am. 2004;86:910-5).

Several authors have advocated selected arteriography based upon physical exam, Dr. McDonough said. However, there have been reports in the literature of popliteal artery injury secondary to knee dislocation presenting with normal distal pulses.

A 2002 metaanalysis of 116 articles concluded that abnormal pedal pulses are not sensitive enough to detect a surgical vascular injury and recommended liberal use of angiography, Dr. McDonough said (J. Trauma 2002;53:1109-14). The ankle brachial (arterial pressure) index has been proposed as a noninvasive and less costly test to assess arterial function, but a 1991 study concluded that the method's sensitivity was a poor runner-up to arteriography (Ann. Surg. 1991;214:737-41).

BY BRUCE K. DIXON

Chicago Bureau
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Title Annotation:Musculoskeletal Disorders
Author:Dixon, Bruce K.
Publication:Family Practice News
Geographic Code:1USA
Date:Aug 15, 2006
Words:526
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