The effect of knee effusions on KT-1000 arthrometry. A cadaver study.
We studied five fresh-frozen lower extremity cadaveric specimens to assess the effect of knee effusions on KT-1000 arthrometry. Part 1 consisted of serial 10-ml injections (up to 100 ml) of saline into each knee and measurements of midpatellar knee circumference and anterior displacement using the KT-1000 arthrometer at 67, 89, and 134 N after each 10-ml increment. Part 2 consisted of evacuation of the saline and transection of the anterior cruciate ligament through a 2-cm medial parapatellar arthrotomy. Each knee again underwent the part 1 protocol. Sequential injections in parts 1 and 2 showed incremental increases in knee circumference and KT-1000 arthrometer measurements for all three force levels. A 3-mm increase in anterior translation compared with the value at 0-ml injection was obtained by the 70-ml injection point in both groups. At the 70-ml injection point, the patella was ballottable, thereby affecting anterior measurements-despite posterior force on the patella sensor pad-because of the KT-1000 arthrometer reference level at midpatella. This increase in KT-1000 arthrometer readings could erroneously imply anterior cruciate ligament disruption in the clinical situation of right-to-left comparison. We conclude that clinicians using the KT-1000 arthrometer should aspirate knees that have effusions and a ballottable patella to minimize false-positive readings.
Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA.
R W
RW
Wright
S J
SJ
Luhmann
D000368:Aged; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D000886:Anthropometry / Q000295:instrumentation; D002102:Cadaver; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology* / Q000473:pathology; D008297:Male; D010329:Patella / Q000033:anatomy & histology / Q000473:pathology; D012399:Rotation; D012965:Sodium Chloride; D013314:Stress, Mechanical; D013582:Synovial Fluid
D012965:Sodium Chloride