Relationship between peak knee adduction moment and Kellgren and Lawrence grade in patients with medial compartment knee osteoarthritis

![CDATA[Rationale/Objectives: Biomechanically, medial compartment knee osteoarthritis (MCKOA) has been associated with a greater peak knee adduction moment (KAM). Clinically, Kellgren and Lawrence (KL) grading system is a commonly used radiological classification to indicate the severity of MCKOA. Although strong correlation between peak KAM and KL grades in patients with MCKOA has been previously reported, in view of the large minimal detectable differences in the peak KAM, it is very possible that peak KAM may not be sensitive enough to differentiate KL grades. Hence, this study examined the relationship between KAM and KL grade, as well as compared the peak KAM difference across patients with different KL grades. Methods: Twenty five patients with different severity of MCKOA were recruited from the Prince of Wales Hospital. We measured KAM of the affected knee joint using previously established methods. KL grade of the affected knee was rated by a single orthopedic surgeon. Spearman’s rank correlation (rho) was used to examine the relationship between KAM and KL grade. One-way ANOVA was also employed to compare the KAM difference across KL grades. Results: Peak KAM was significantly correlated to KL grade (rho=0.683; p<0.001) Patients with KL grade 4 MCKOA exhibited significant greater peak KAM than patients with less severity (p<0.05). However, peak KAM was similar between patients with KL grade 1-3 (p=0.291). Conclusions: Peak KAM may not be a sensitive surrogate to indicate the KL grade in patients with MCKOA and other measures should be used to monitor the disease progression.]]