Abstract
Introduction and aims: Osteoarthritis (OA) of the knee is a widespread problem, yet there is little known about the kinematics of the osteoarthritic knee, and nothing about the tibio-femoral contact pattern. This study aimed to describe the role of tibio-femoral interface events in articular surface wear and degenerative change.
Method: Fourteen subjects with symptomatic OA in one knee, and no pain or injury in the contralateral knee were recruited. The tibio-femoral contact pattern was recorded for both knees, while performing a supine leg-press from 0 to 90 degrees flexion against a 150N load. Severity of osteoarthritis was measured by Kellgren Lawrence grade, bone mineral density (BMD) using Dual Energy X-ray Absorptiometry close to the subchondral bone, diagnostic MRI, and joint damage recorded at knee arthroplasty. Pain and disability was recorded using a WOMAC questionnaire.
Results: Severity of OA in the knees ranged from grade two to four (mode=4) in the symptomatic knee, and from zero to three (mode=0) in the contralateral knee. Contact in the lateral compartment of the knee was more anterior on the tibial plateau than healthy knees (p≤ 0.01), and this was associated with severity of OA (p≤ 0.01). Contact in the medial compartment was also more anterior on the tibial plateau, and this was associated with severity of OA. Abnormality in tibio-femoral contact patterns was associated with disability reported by the WOMAC score (r= 0.54). There was no significant difference in BMD between the OA and contralateral knees. However, the BMD was correlated with pain and physical function of the WOMAC score, that is, as function decreased, bone density increased in the arthritic compartment (r = 0.49 to 0.63; p≤ 0.01).
Conclusion: Severity of osteoarthritis was associated with loss of rollback normally coupled with flexion, especially in the lateral compartment. Consequently longitudinal rotation was lost. In severe osteoarthritis, ACL integrity did not affect the contact pattern. Kinematic abnormalities may explain loss of range of motion, and patterns of wear in osteoarthritic knees.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
One or more of the listed authors are receiving or have received benefits or support from a recognised academic body for the pursuance of the study.
