Background & Aims

Central sensitization is reportedly involved in muscle co-contraction during unloaded knee extension in knee osteoarthritis (OA) [1]. However, it is unclear whether central sensitization is involved in muscle co-contraction of the medial muscles during gait, thereby contributing to OA progression. This study aimed to clarify whether central sensitization is associated with co-contraction of the vastus medialis and semitendinosus muscles during gait in people with end-stage knee OA.

Methods

This study included 70 participants (16 men and 54 women; mean age: 73.5 ± 6.4 years) with end-stage knee OA who were candidates for total knee arthroplasty. The co-contraction ratios (CCR) of the medial muscles during the stance phase were calculated by measuring the activity of the affected side of the vastus medialis and semitendinosus muscles during gait with a surface electromyograph. Further, the visual analog scale (VAS) and pressure pain thresholds (PPT) were measured. PPT was measured three times at the medial knee joint and the forearm of the nondominant hand, and the average value was calculated. For statistical analysis, multiple regression analysis was performed using the medial muscle CCR as the dependent variable and age, sex, body mass index (BMI), femorotibial angle (FTA), VAS, local PPT, and distant PPT as independent variables.

Results

The results of each assessment were as follows: BMI 25.6 ± 3.8 kg/m2, FTA 184.9° ± 4.2°, VAS during gait 23.9 ± 21.7 mm, and the CCR of the medial muscles during the stance phase of gait 54.2% ± 21.4%, the local PPT 2.85 ± 1.52 kgf, and the distant PPT 2.27 ± 1.01 kgf. The model of multiple regression analysis in this study was significant (F [2,433] = 0.03, p < 0.05, R2 = 0.22, adjusted R2 = 0.215). Multiple regression analysis showed that only PPT at the distant area significantly affected the medial muscle CCR during the stance phase of gait (? = ?0.53, 95% confidence interval from ?17.94 to ?4.24).

Conclusions

The findings of this study suggest that co-contraction of the vastus medialis and semitendinosus muscles during gait in people with end-stage knee OA is associated with a decrease in the PPT at the distant area. Treatments targeting CS may improve co-contraction.

References

1. Stefanik JJ et al. The relation of peripheral and central sensitization to muscle co-contraction: the MOST study. Osteoarthritis Cartilage. 2020. Sep;28(9):1214-1219.
2. Dixon PC et al. Muscular co-contraction is related to varus thrust in patients with knee osteoarthritis. Clin Biomech. 2018. Dec;60:164-169.

Presenting Author

So Tanaka

Poster Authors

So Tanaka

PhD

Fukuoka Orthopaedic Hospital

Lead Author

E-mail

Topics

  • Assessment and Diagnosis