Decrease in quadriceps inhibition after sacroiliac joint manipulation in patients with anterior knee pain

Background: Evidence exists that conservative rehabilitation protocols fail to achieve full recovery of muscle strength and function after joint injur ies. The lack of success has been attributed to the high amount of muscle i nhibition found in patients with pathologic conditions of the knee joint. C linical evaluation shows that anterior knee pain is typically associated wi th sacroiliac joint dysfunction, which may contribute to the muscle inhibit ion observed in this patient group. Objective: To assess whether sacroiliac joint manipulation alters muscle in hibition and strength of the knee extensor muscles in patients with anterio r knee pain. Design and Setting: The effects of sacroiliac joint manipulation were evalu ated in patients with anterior knee pain. The manipulation consisted of a h igh-velocity low-amplitude thrust in the side-lying position aimed at corre cting sacroiliac joint dysfunction. Before and after the manipulation, torq ue, muscle inhibition, and muscle activation for the knee extensor muscles were measured during isometric contractions using a Cybex dynamometer, musc le stimulation, and electromyography, respectively. Participants: Eighteen patients (mean age, 30.5 rt 13.0 years) with either unilateral (n = 14) or bilateral (n = 4) anterior knee pain. Results: Patients showed substantial muscle inhibition in the involved and the contralateral legs as estimated by the interpolated twitch technique. A fter the manipulation, a decrease in muscle inhibition and increases in kne e extensor torques and muscle activation were observed, particularly in the involved leg. In patients with bilateral anterior knee pain, muscle inhibi tion was decreased in both legs after sacroiliac joint adjustment. Conclusions: Spinal manipulation might offer an interesting alternative tre atment for patients with anterior knee pain and muscle inhibition. Because this clinical outcome study was of descriptive nature rather than a control led design, biases might have occurred. Thus the results have to be verifie d in a randomized, controlled, double-blinded trial before firm conclusions can be drawn or recommendations can be made.