title: Instrumented measurement of anteroposterior and inversion-eversion laxity of the normal ankle joint complex.
abstract: Manual examination is the most common method for the evaluation of ankle anteroposterior (AP) and inversion-eversion (I-E) laxity. Objective assessment data of normal ankle laxity must be provided before comparison with an injured ankle can be made. The purpose of this study was to compare AP translation and I-E rotation at three force loads between dominant and nondominant ankles and to assess the test-retest reliability of a portable arthrometer in obtaining these measurements. The arthrometer consists of a frame that is fixed to the foot, a pad that is attached to the tibia, and a load-measuring handle that is attached to the foot plate through which the load is applied. A six-degrees-of-freedom spatial kinematic linkage system is connected between the tibial pad and the foot frame to measure motion. Instrumented measurement testing of total AP displacement and I-E rotation of both ankles was performed in 41 subjects (21 men and 20 women; mean age, 23.8 +/- 4.4 years). Subjects had no history of ankle injury. Subjects were tested in the supine position while lying on a table with the knee secured in extension and the foot positioned at 0 degrees of flexion. Laxity was measured from total AP displacement (millimeters) during loading to 125 N of AP force and from total I-E rotation (degrees of range of motion) during loading to 4000 N-mm. Reliability was evaluated by calculating intraclass correlation coefficients (2,1) at 75 N, 100 N, and 125 N of AP force and at 2000, 3000, and 4000 N-mm torque loads. Mean differences for displacement and rotation between the dominant and nondominant ankles at each of the force and torque loads were analyzed by dependent t-tests. For both the dominant and nondominant ankles, respectively, the reliability coefficients at each of the force loads for AP displacement (range, 0.82-0.89) and I-E rotation (range, 0.86-0.97) were high. The t-test analyses showed no significant differences (P > or = 0.05) for total AP displacement or I-E rotation between the dominant and nondominant ankles at any of the force loads. The results are clinically useful in providing information about the reliability of measures at different AP and I-E force loads using a portable ankle ligament arthrometer.
authors.affiliation: Department of Orthopaedic Surgery, University of South Alabama, Mobile 36688, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Kovaleski
authors.forename: L R
authors.initials: LR
authors.lastname: Gurchiek
authors.forename: R J
authors.initials: RJ
authors.lastname: Heitman
authors.forename: J M
authors.initials: JM
authors.lastname: Hollis
authors.forename: A W
authors.initials: AW
authors.lastname: Pearsall
mesh_terms: D000328:Adult; D016512:Ankle Injuries / Q000175:diagnosis; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis*; D008023:Ligaments, Articular / Q000502:physiology*; D008297:Male; D009985:Orthopedics; D015203:Reproducibility of Results; D012107:Research Design / Q000592:standards*; D012399:Rotation