Trigger points in patients with lower limb osteoarthritis

Objectives: Studies have shown that osteoarthritis [OA] is associated with hyperalgesia and weakness in muscles resulting in muscle strain, poor positioning, and inappropriate muscle use. Hyperalgesia and indirect injuries resulting from forces generated within the musculoskeletal structures during activity may result in the formation of trigger points [TrPs]. The purpose of this study was to compare the occurrence of TrPs in healthy controls and patients with OA of the lower limbs. Methods: Both lower limbs of fourteen OA patients and an equal number of age and sex matched healthy controls were palpated for the presence of TrPs by examining the local twitch reaction, taut bands, nodules, and the pattern of pain radiation and pain referral. Results: Significantly greater numbers of latent TrPs in Muscles acting on the hip joint were present in the OA patients with OA secondary to trauma [N = 9], as compared to the controls without any history of trauma [N = 9] [P < 0.05]. Increased TrPs were found in muscles acting on the knee joint in knee OA as compared to hip OA [P=0.016]. The total number of TrPs in OA patients correlated with the radiological scores of OA [Spearman's R = 0.57, P = 0.041. The pain evoked by pressure to the TrPs in OA patients was associated with a significantly larger radiation and referral as compared to the control subjects [P < 0.05]. Conclusion: The large number of TrPs in secondary [traumatic] OA patients may be due to hyperalgesia resulting from the chronic nociceptive inputs from the sensitized joint nociceptors and central sensitization. The treatment or elimination of TrPs may play an important role in pain relief of chronic OA of lower limbs. (C) 2001 by The Haworth Press, Inc. All rights reserved.