Purpose: To determine whether transcutaneous electrical nerve stimulation (TENS) and focal knee joint cooling will affect the quadriceps central activation ratio (CAR) in patients with tibiofemoral osteoarthritis.
Methods: Thirty-three participants with diagnosed tibiofemoral osteoarthritis were randomly allocated to the 45-min TENS treatment (six males and four females, 56 +/- 10.1 yr, 174.11 +/- 10.78 cm, 89.34 +/- 21.3 kg), the 20-min focal knee joint cooling treatment (six males and five females, 58 +/- 8.4 yr, 176.41 +/- 8.29 cm, 83.18 +/- 17.97 kg), or the control group (five males and seven females, 54 +/- 9.9 yr, 166.37 +/- 13.07 cm, 92.14 +/- 25.37 kg). Volitional quadriceps activation, maximal voluntary isometric contraction, and subjective pain measurements were conducted at baseline and at 20, 30, and 45 min. The 20-min focal knee joint cooling intervention consisted of two 1.5-L ice bags to the anterior and posterior aspects of the knee. The TENS group received 45 min of a sensory, biphasic square wave stimulation (150-mus phase duration and 150 pps) from four 2 x 2-inch electrodes positioned around the patella.
Results: : TENS resulted in a significantly higher percent change in CAR scores compared with control at 20 min (6.4 +/- 4.8 vs -3.5 +/- 8, P = 0.006), 30 min (9.7 +/- 10.16 vs -1 +/- 7.9, P = 0.025), and 45 min (11.25 +/- 6.96 vs 0.81 +/- 9.4, P = 0.029). Focal knee joint cooling resulted in significantly higher percent change scores compared with the control group at 20 min (5.75 +/- 7.25 vs -3.5 +/- 8, P = 0.009) and trended to be higher at 45 min (9.06 +/- 9.63 vs 0.81 +/- 9.4, P = 0.098). No significant differences in percent change for CAR were found between the TENS and the focal knee joint cooling group.
Conclusions: Both TENS and focal knee joint cooling increased the quadriceps CAR immediately after application in participants with tibiofemoral osteoarthritis.