Abstract
Aims: We used dynamic radiostereometry (RSA) to record the kinematics of knee with medial arthritis during active extension and weight bearing. Methods: 15 patients with medial knee arthrosis (OA) and 10 controls were studied. The knee motions were recorded using 2–4 sequential simultaneous exposures/s when the subjects ascended a platform. Each series constituted 10 exposures (range 5–15) exposed during 3–5 s. Translations of the circular centre of the medial (MFFC) and lateral (LFFC) femoral condyles and of the tibial plateau centre were computed separately. Repeated measure ANOVA was used. Results: In the OA group the tibia was rotated 4.6û less internally at 50û exion,ßwhich changed to 2.1û less internally at 20û compared with the controls (p=0.035). The LFFC displaced 0.8 mm anteriorly in the OA group and 1.5 mm posteriorly in the normal knees (p=0.046). It displaced 0.6 mm distally in the OA and 0.5 mm proximally in the normal knees (p=0.007). MFFC showed nearly no proximal/distal translation in the OA knees. It displaced 1.6 mm proximally p< 0.0005) in the normal knees. The tibial plateau center shifted 3.5 mm less anteriorly and 2.4 mm less distally than in the OA group (p=0.000). Conclusion: The changed tibial rotations and anterior/posterior translations of both the lateral femoral condyle and the tibial plateau center showed similarities to cases with rupture of the ACL. It might be that the patients with medial arthrosis actively avoided internal rotation to decrease pain or the ACL had lost its function due to degenerative changes. The difference in proximal/distal displacement might be related to loss of cartilage in the medial compartment.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
