A prospective magnetic resonance imaging study of the incidence of posterolateral and multiple ligament injuries in acute knee injuries presenting with a hemarthrosis.
OBJECTIVE
The purpose of this study was to determine whether the incidence of posterolateral knee injuries, as well as other concurrent knee ligament injuries, could be obtained from a prospective evaluation of magnetic resonance imaging scans in patients with an acute knee injury with a hemarthrosis.


METHODS
We prospectively documented all patients with acute (within 30 days) knee injuries with a hemarthrosis over a 90-day period who underwent 1.5-T magnetic resonance imaging at a large referral imaging facility with 6 sites, effectively covering a large metropolitan area. The anterior cruciate ligament, superficial medial collateral ligament, and posterior cruciate ligament (PCL) and the following individual structures of the posterolateral corner were evaluated for high-grade injury: fibular collateral ligament, popliteus tendon, and popliteofibular ligament.


RESULTS
Out of 331 consecutive acute knee injuries with a hemarthrosis, 265 ligament injuries occurred in 187 patients (56%). Of these 187 patients with ligament injuries, 126 had isolated ligament injuries and 61 (33%) had combined multiple ligament injuries. Of the 187 patients with knee ligament injuries, 83 (44%) had isolated anterior cruciate ligament tears, 28 (15%) had isolated superficial medial collateral ligament tears, 11 (5%) had isolated PCL tears, and 4 (2.1%) had isolated posterolateral knee tears. Of the patients with posterolateral knee structure injuries, 87% (26/30) had multiple ligament injuries, with the overall incidence of posterolateral knee injuries among all knee ligament injuries being 16% and among all acute knee injuries with a hemarthrosis being 9.1%. Of the 27 patients with PCL tears, 16 (52%) had combined multiple ligament injuries.


CONCLUSIONS
This study shows that in this population, the incidence of posterolateral knee injuries in patients with acute knee ligament injuries with a hemarthrosis was 9.1%. It also verified that most PCL and posterolateral corner injuries occur in combination with other ligament injuries.


METHODS
Level II, development of diagnostic criteria on the basis of consecutive patients with a universally applied gold standard.
Sports Medicine and Shoulder Divisions, Department of Orthopaedic Surgery, University of Minnesota, Minneapolis 55454, USA. lapra001@umn.edu
Robert F
RF
LaPrade
Fred A
FA
Wentorf
Hollis
H
Fritts
Cooper
C
Gundry
C David
CD
Hightower
D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000473:pathology; D000070598:Anterior Cruciate Ligament Injuries; D005500:Follow-Up Studies; D006395:Hemarthrosis / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D015994:Incidence; D007718:Knee Injuries / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008910:Minnesota / Q000453:epidemiology; D009104:Multiple Trauma; D016119:Posterior Cruciate Ligament / Q000293:injuries* / Q000473:pathology; D011446:Prospective Studies; D012421:Rupture; D015599:Trauma Severity Indices