A new biomechanical model for the functional assessment of knee osteoarthritis.

The severity of symptoms in osteoarthritis (OA) of the knee can be difficult to assess. A new method for assessing medial compartment OA of the knee is proposed. The purpose of this study was to determine if a relationship exists between the severity of OA and single limb stance knee adduction moment (SSKAM). Fourteen patients with medial compartment OA of the knee were tested and compared with 14 age-matched volunteers. WOMAC OA index scores were documented. Biomechanical data were collected from a single Kistler force platform and a six-camera ProReflex motion analysis system, and the knee adduction moments were calculated. A significant difference in the maximum, minimum and mean adduction moments was found between the two groups, and a correlation of r=0.66 for WOMAC physical function subscale, r=0.63 for the WOMAC pain subscale and r=0.63 for the sum of the subscales and mean SSKAM was found. Single limb stance adduction moments provide additional, objective information in the assessment of medial compartment OA of the knee. It may be useful in the selection of patients for surgery and for evaluating various treatment modalities for medial compartment OA of the knee.