Background Historically pain in OA considered to be nociceptive one. But recent studies has shown that in some cases mechanisms of chronic pain in knee osteoarthritis (OA) are likely to be complex. For characterizing knee pain 28-34% patients can use neuropathic descriptors such as burning, tingling, numbness. These sensor phenomena are caused by specific changes in the posterior horn – central sensitization and forms dysfunctional pain. This type of pain accompanies with dysfunction of biochemical process in CNS and does not characterize with organic changes of CNS. Dysfunctional pain is also typically characterized with hyperalgesia and pronounced affective disorders.
Objectives To reveal key features of dysfunctional pain in pt with knee OA and demonstrate its correlation with clinical picture and intensity of chronic pain.
Methods 89 women (middle age 58±5,4), II-III grade by Kellgren-Lawrence with chronic knee OA were neurologically tested. No neurological deficit was found. Examination of sensitive sphere revealed primary hyperalgesia (in the damaged knee) and also referred hyperalgesia in the intact region (shank and even hip). According to sensitive changes the pts were divided into two groups: pts with primary hyperalgesia and pts with referred hyperalgesia. In our trial we assed clinical rheumatological picture, X-ray and US of the knee. NP pain scales (Paindetect and DN4) were used. Duration of knee symptoms, knee OA severity (WOMAC) and pain intensity were taken into consideration. We used the prevalence of anxiety and depressive disorders in population with OA, examined the interrelationships between severity of pain and emotional disturbances by Hospital Anxiety and Depression scale.
Results Neurologic examination revealed referred hyperalgesia not only knee localization but also hip and shank localization in 41,5%, (n=37) had and in 58,5% (n=52). No somatosensory defects were found. There was no association with age, body index, duration of knee OA, quality of life and level of structural changes. The presence of referred hyperalgesia accompanied with high levels of neuropathic pain scales, correlated with higher pain intensity (VAS), poor WOMAC and significantly associated with higher level of depression. The presence of referred hyperalgasia accompaned with more often observed neuropathic discriptors: numbness 60,5% vs 39,5%, current rush 51,9% vs 48,1% and tingling 55% vs 45%.
Conclusions Chronic OA is a complex of mechanisms and includes nociceptive and dysfunctional pain. Dysfunctional pain in OA can be visualized clinically by the prevalence of referred pain, that was revealed in 41,5%. The degree of spreading sensitization is correlated with the level of clinical pain and does not correlate with structural changes. Additionally as screening test can be used neuropathic scales (DN4, PainDETECT), that include the most typical neuropathic transcriptors
Disclosure of Interest None declared