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[Anterior cruciate ligament function: a non-invasive quantitative technique]
V Antolic1, V Pavlovcic, U Stanic
1Centre médical universitaire, Département de chirurgie orthopédique, Ljubljana, Slovénie.
Purpose Of The Study:
The purpose of the study was to develop a new non-invasive and quantitative method for evaluation of the anterior cruciate ligament function.
Patients And Methods:
The new method was tested in 24 asymptomatic subjects and in 58 patients (39 males and 19 females) with arthroscopically proven unilateral rupture of the anterior cruciate ligament. Anterior displacement of the tibia with the knee in 20 degrees flexion was achieved by using a redesigned device, constructed originally for stress-radiography, and detected by a 3-D optical motion analysis system.
Results:
In the normal group, the average difference (d) in anterior displacement of the tibia between the left and the right side under a displacement force of 250N was 0.56 mm (range 0.1 mm to 1.9 mm) or 17 p. 100 (range 2 p. 100 to 64 p. 100), while in patients the average difference (d) in anterior displacement of the tibia between the injured and uninjured side under a displacement force of 250N was 4.02 mm (range 0.6 mm to 9.4 mm) or 133.6 p; 100 (range 26 p. 100 to 451 p. 100). By the criteria for false negative results, i.e. the maximum value of the parameter d in normal subjects (1.9 mm and 64 p. 100), 10 p. 100 of the patients (6 patients) fell into the normal group. According to the criteria of false positive results, i.e. the minimum value of the parameter d in patients (0.6 mm and 26 p. 100), 17 p. 100 of the normal subjects (4 normal subjects) fell into the group of patients. The achieved level of differentiation is in the similar range as the most frequently used present methods.
Discussion:
The main advantage of the newly developed noninvasive optical measurement technique is that the direction of force and the amplitude and site of application are accurately defined and documented, and that dislocation movement of the tibia towards the femur during the application of a growing force is continuously monitored with the 3-D optical system and that it allows for several consecutive assessments based on statistical data.