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Evaluation of Acute Knee Pain in Primary Care

Jeffrey L. Jackson, MD, MPH; Patrick G. O'Malley, MD, MPH; and Kurt Kroenke, MD
[+] Article, Author, and Disclosure Information

From the Uniformed Services University of the Health Sciences, Bethesda, Maryland; Walter Reed Army Medical Center, Washington, DC; and Indiana University School of Medicine and Regenstrief Institute, Indianapolis, Indiana.

Disclaimer: The opinions in this article are those of the authors and should not be construed to reflect those of the U.S. Army or the U.S. Department of Defense.

Acknowledgments: The authors thank Yoshiko Jaeggi for the illustrations.

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: Jeffrey L. Jackson, MD, MPH, Medicine-EDP, 4301 Jones Bridge Road, Bethesda, MD 20814.

Current Author Addresses: Dr. Jackson: Medicine-EDP, 4301 Jones Bridge Road, Bethesda, MD 20814.

Dr. O'Malley: 4103 Oliver Street, Chevy Chase, MD 20815.

Dr. Kroenke: Regenstrief Institute, 1050 Wishard Boulevard, Indianapolis, IN 46202.

Ann Intern Med. 2003;139(7):575-588. doi:10.7326/0003-4819-139-7-200310070-00010
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Background: The evaluation of acute knee pain often includes radiography of the knee.

Objective: To synthesize the literature to determine the role of radiologic procedures in evaluating common causes of acute knee pain: fractures, meniscal or ligamentous injuries, osteoarthritis, and pseudogout.

Data Sources: MEDLINE search from 1966 to October 2002.

Study Selection: We included all published, peer-reviewed studies of decision rules for fractures. We included studies that used arthroscopy as the gold standard for measuring the accuracy of the physical examination and magnetic resonance imaging (MRI) for meniscal and ligamentous knee damage. We included all studies on the use of radiographs in pseudogout.

Data Extraction: We extracted all data in duplicate and abstracted physical examination and MRI results into 2 2 tables.

Data Synthesis: Among the 5 decision rules for deciding when to use plain films in knee fractures, the Ottawa knee rules (injury due to trauma and age >55 years, tenderness at the head of the fibula or the patella, inability to bear weight for 4 steps, or inability to flex the knee to 90 degrees) have the strongest supporting evidence. When the history suggests a potential meniscal or ligamentous injury, the physical examination is moderately sensitive (meniscus, 87%; anterior cruciate ligament, 74%; and posterior cruciate ligament, 81%) and specific (meniscus, 92%; anterior cruciate ligamen, 95%; and posterior cruciate ligament, 95%). The Lachman test is more sensitive and specific for ligamentous tears than is the drawer sign. For meniscal tears, joint line tenderness is sensitive (75%) but not specific (27%), while the McMurray test is specific (97%) but not sensitive (52%). Compared with the physical examination, MRI is more sensitive for ligamentous and meniscal damage but less specific. When the differential diagnosis for acute knee pain includes an exacerbation of osteoarthritis, clinical features (age >50 years, morning stiffness <30 minutes, crepitus, or bony enlargement) are 89% sensitive and 88% specific for underlying chronic arthritis. Adding plain films improves sensitivity slightly but not specificity. Plain films for pseudogout are not sensitive or specific, according to limited-quality studies.

Conclusions: We recommend the Ottawa knee rules to decide when to obtain plain films for suspected knee fracture. A careful physical examination should be sufficient to decide whether to refer patients with potential meniscal and ligament injuries, and we prefer clinical criteria rather than plain films for evaluating osteoarthritis. We do not recommend using plain films to diagnose pseudogout.


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Common maneuvers of the knee for assessing possible ligamentous and meniscal damage.Top leftAnterior drawer testTop rightLachman testBottom leftPivot testBottom rightMcMurray testNot shown:Joint line tenderness

. . Place patient supine, flex the hip to 45 degrees and the knee to 90 degrees. Sit on the dorsum of the foot, wrap your hands around the hamstrings (ensuring that these muscles are relaxed), then pull and push the proximal part of the leg, testing the movement of the tibia on the femur. Do these maneuvers in 3 positions of tibial rotation: neutral, 30 degrees externally, and 30 degrees internally rotated. A normal test result is no more than 6 to 8 mm of laxity. . . Place patient supine on examining table, leg at the examiner's side, slightly externally rotated and flexed (20 to 30 degrees). Stabilize the femur with 1 hand and apply pressure to the back of the knee with the other hand with the thumb of the hand exerting pressure placed on the joint line. A positive test result is movement of the knee with a soft or mushy end point. . . Fully extend the knee, rotate the foot internally. Apply a valgus stress while progressively flexing the knee, watching and feeling for translation of the tibia on the femur. . . Flex the hip and knee maximally. Apply a valgus (abduction) force to the knee while externally rotating the foot and passively extending the knee. An audible or palpable snap during extension suggests a tear of the medial meniscus. For the lateral meniscus, apply a varus (adduction) stress during internal rotation of the foot and passive extension of the knee. . Palpate medially or laterally along the knee until one comes to the joint line between the femur and tibial condyles. The presence of pain on palpation is a positive finding.

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Appendix Figure. Fitted ROC curves for physical examination and magnetic resonance imaging ( ) examination of knee pathology: medical meniscus ( ), lateral meniscus ( ), anterior cruciate ligament tear ( ), and posterior cruciate ligament tear ( ).
Fitted receiver-operating characteristic (ROC) curves.MRItop lefttop rightbottom leftbottom right
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Submit a Comment/Letter
Posted on March 26, 2006
Brent B Meserve
Franklin Pierce College
Conflict of Interest: None Declared

I was hoping the authors could comment on how the equation for SROC is specifically used. In other words, is each sensitivity value from each study in the meta-analysis entered into the logarithmic equation to generate a false positive value? Are these values then graphed like a traditional ROC? Is the curve smooth with this approach?

Thank you, Brent Meserve SPT

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