Abstract
Aim: A method of analysing the kinematics of the knee has been developed using magnetic resonance imaging (MRI) at regular intervals of knee motion. This method was tested for reliability and applied to normal and injured knees.
Method: MRI scans were used to study knees of 11 healthy subjects and knees of eight patients ACL with injuries. Scans were taken at 15 degrees intervals from 0 degrees to 90 degrees flexion, using a positioning jig to enable scanning with the knees either loaded or unloaded. The tibiofemoral contact points were mapped for each knee position, loaded and unloaded, in the medial and lateral compartments. The data were analysed for repeatability by interclass correlation and compared with known data.
Results: High reliability was achieved using T1 weighted fast spin echo images, scanned into Adobe Photoshop, or gradient echo sequences, downloaded as Dicom files and analysed using Osiris. Gradient echo sequences have advantages in efficiency without loss of reliability. Analysis of ACL-deficient knees confirmed aberrant contact-point behaviour compared with the non-injured side. The results showed that right and left normal knees and loaded and unloaded uninjured knees did not demonstrate significant differences but that medial and lateral condyles did demonstrate significant differences reflecting the longitudinal rotation of the knee during flexion.
Conclusions: The technique of MR imaging of the knee for kinematic analysis has been demonstrated to be robust and reliable. This technique may be applied to assessments of the effect of knee injury on the biomechanics of the knee or the results of surgical and physiotherapy interventions.
The abstracts were prepared by Professor A. J. Thurston. Correspondence should be addressed to him at the Department of Surgery, Wellington School of Medicine, PO Box 7343, Wellington South, New Zealand
