LOWER-LIMB ALIGNMENT AND FOOT ANGLE ARE RELATED TO STANCE PHASE KNEE ADDUCTION IN NORMAL SUBJECTS - A CRITICAL ANALYSIS OF THE RELIABILITY OF GAIT ANALYSIS DATA

Anatomic and mechanical factors that affect loading in the knee joint can contribute to pathologic changes seen at the knee in degenerative joint disease and should be considered in treatment planning. The obje ctives of this study were to quantify the relationships between the al ignment of the bones of the lower extremity, foot progression angle, a nd knee adduction moment, and to determine the reliability of our gait measurements. Gait analysis and complete radiographic evaluation of t he lower extremity were performed on 11 healthy subjects. The gait mea surements were recorded with an optoelectronic digitizer and a multi-c omponent force plate. The subjects who had radiographic measurements i ndicative of varus alignment of the lower extremity had statistically higher peaks in knee adduction moment in early stance. Conversely, tho se with valgus alignment of the lower extremity had statistically lowe r peaks in knee adduction moment in early stance. The subjects who had a large toe-out angle and low ankle inversion moment peaks in late st ance had significantly lower peaks in knee adduction moment in late st ance. These significant (low to moderate) correlations suggest that th e limbs with more valgus alignment and those with a toe-out gait exhib ited a reduced peak adduction moment at the knee. To verify the reprod ucibility of the data, gait analysis testing was performed on each low er limb on 2 separate days for each subject. Analysis of variance show ed that there was no significant difference between test limbs or test days for each subject. Our results suggest that the alignment of the lower limb and the foot progression angle, which can be readily measur ed in a clinical setting, can serve as predictors of knee joint loadin g in healthy individuals. These findings may have important implicatio ns for both surgical and nonsurgical treatment of abnormalities of the knee joint.