Instrumented measurement of anterior knee laxity in patients with acute anterior cruciate ligament disruption

Abstract

Instrumented anterior/posterior laxity measurements were performed on 138 patients evaluated within 2 weeks of injury with their first traumatic knee hemarthrosis. All patients were tested with the MEDmetric Arthrometer model KT-1000 in a knee injury clinic. Seventy-five of the patients had knee arthroscopy. Thirty-three had arthrometer laxity tests under anesthesia. Eighty-seven percent of patients arthroscoped had anterior cruciate ligament (ACL) tears and 41% had meniscus tears. One hundred twenty normal subjects were tested to establish normal anterior laxity values. Three tests were used to evaluate anterior laxity: anterior displacement between a 15 and 20 pound force (compliance index), anterior displacement with a 20 pound force, and anterior displacement with a high manually applied force. Displacement measurements in normal subjects revealed a wide range of normal laxity with a small right knee-left knee difference. For example, the 20 pound anterior displacement range was 3 to 13.5 mm with a right knee-left knee difference (mean +/- SD, 0.8 +/- 0.7 mm). Eighty-eight percent of the normals had a right-left difference of less than 2 mm. In the 53 patients arthroscoped who had complete ACL tears, the anterior laxity measurements performed in the clinic were suggestive or diagnostic of pathologic anterior laxity in 50 patients.

Anterior cruciate ligament assessment using arthrometry and stress imaging

“…The most common data interpretation measure is SSD, using the patient's uninjured knee as a reference. Multiple groups have shown better consistency in SSD measurements as opposed to single-knee measurements, both among different patients, as well as in test-retest analysis of individual knees [25,29,38,68,75]. Appropriate SSD thresholds vary by device, but are generally 2-3 mm.…”

Performance-based functional outcome for children 12 years or younger following anterior cruciate ligament injury: a two to nine-year follow-up study

“…Saggital knee joint laxity was measured by one experienced senior physical therapist (MAR) with a KT-1000 arthrometer (Med-Metric, San Diego, California, USA) to record anterior displacement of the tibia relative to the femur [10]. Maximum manual force measurement was used in the analysis.…”

An investigation to examine the inter-tester and intra-tester reliability of the Rolimeter® knee tester, and its sensitivity in identifying knee joint laxity

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