Anterior tibial laxity using the GNRB® device in healthy knees.

BACKGROUND

GRNB® is a non-radiating power tool that allows the evaluation of the anterior tibial translation.

HYPOTHESIS

The pressure exerted by the system against the patella and the body mass index (BMI) could affect the anterior tibial translation when we repeat the measurements in healthy knees.

MATERIALS AND METHODS

We retrospectively evaluated the measurements of anterior knee laxity in healthy knees carried out by the GNRB® in 69 consecutive patients who underwent anterior cruciate ligament (ACL) repair in the contralateral knee. Two measurements were carried out, the initial measurements (M1), and then repeated at a mean of seven months (M2) (4.9 to 13months).

RESULTS

There were 38 women and 31 men with an average age of 31years. In healthy knees, the Mean average anterior translation was 5.4±4mm with an average patellar force of 35.8 at time M1. The average anterior translation was 4.9±4mm with an average patellar force of 47 at time M2. There was a significant difference between the measurements M1 and M2 (P<0.03). The tightening force was significantly different between the two sets of measurements (P<10-7). There was a negative correlation between the pressure applied on the patella and anterior knee laxity (P<0.01).

CONCLUSION

The pressure force exerted on the patella during GNRB® affects the measurement of anterior laxity in healthy knees. This raises the problem of the reproducibility of the measurements during repeated examinations at different times.