Does choice of angular velocity affect pain level during isokinetic strength testing of knee osteoarthritis patients?

BACKGROUND

Thigh musculature strength assessment in individuals with knee osteoarthritis is routinely performed in rehabilitative settings. A factor that may influence results is pain experienced during testing.

AIM

To assess whether pain experienced during isokinetic testing in individuals with knee osteoarthritis is dependent on the angular velocity prescribed.

DESIGN

Experimental, repeated measures.

SETTING

University laboratory.

POPULATION

Thirty-five individuals (19 women, 16 men) with tibiofemoral osteoarthritis.

METHODS

Participants performed three randomized sets of five maximal concentric extension-flexion repetitions at 60°/s, 90°/s and 120°/s. Pain intensity was measured immediately after the completion of each set. Strength outcomes for each set were the average peak moment.

RESULTS

Across gender, pain level was not significantly affected by testing velocity (P=0.18, η(p)(2) =0.05). There was a trend of women reporting more pain than men across all testing velocities, however this comparison did not reach statistical significance (P=0.18, η(p)(2)=0.05). There was a significant main effect of testing velocity on strength, with the highest level attained at 60°/s. However, no difference in strength was noted when testing was performed at 90°/s or 120°/s.

CONCLUSION

A large variation in pain scores within and across conditions and gender was noted, suggesting that at the current stage: 1) isokinetic angular velocity prescription be performed on an individual patient basis; and 2) improvements in the manner pain is recorded are needed in order to reduce the variations in pain scores.

CLINICAL REHABILITATION IMPACT

Individual prescription of angular velocity may be necessary for optimal strength output and reduction of pain during effort exertion in this patient population.