Characteristics of lower limb skeletal muscle activity during walking in patients with knee osteoarthritis and knee extensor weakness: Comprehensive assessment using positron emission tomography.

PURPOSE: To compare the whole-body muscles glucose metabolism during walking among patients with knee osteoarthritis (KOA) with and without knee extensor weakness using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET).

METHODS

Participants were divided into group A (n = 7) with good and group B (n = 15) with poor knee extensor strength, based on a weight-bearing ratio of 0.45 Nm/kg of the knee extensor strength required for walking adaptation. After treadmill walking task, FDG-PET computed tomography was performed, and standardised uptake values of glucose metabolism were calculated. Hip abductor and knee extensor strengths were measured using a handheld dynamometer. A comparison between the two groups and investigation into the correlation between glucose metabolism and muscle strength (hip abductor and knee extensor) were conducted.

RESULTS

No significant differences were observed in overall glucose metabolism; However, when adjusting for sex between the two groups, Group B exhibited higher glucose metabolism in the tibialis anterior muscle (P = 0.04). Furthermore, glucose metabolism in the rectus femoris muscle showed a negative correlation with muscle strength during isometric contractions for hip abductor and knee extensor.

CONCLUSION

Patients with KOA exhibiting reduced knee extensor strength have increased glucose metabolism in the tibialis anterior.