Identifying participants with knee osteoarthritis likely to benefit from physical therapy education and exercise: A hypothesis‐generating study

Abstract

BackgroundThe purpose of this investigation was to undertake a hypothesis‐generating study to identify candidate variables that characterize people with knee osteoarthritis who are most likely to experience a positive response to exercise.MethodsOne hundred and fifty participants with knee osteoarthritis participated in this observational, longitudinal study. All participants received a standard exercise intervention that consisted of 20‐min sessions two to three times a week for three months. The classification and regression tree methodology (CART) was used to develop prediction of positive clinical outcome. Positive pain and disability outcomes (dependent variables) were defined as an improvement in pain intensity by >50% or an improvement of five or more on the Oxford knee score, respectively. The predictor variables considered included age, sex, body mass index, knee osteoarthritis severity (Kellgren/Lawrence grade), pain duration, use of medication, range of knee motion, pain catastrophizing, self‐efficacy and knee self‐perception.ResultsFifty‐five participants (36.6%) were classified as responders for pain intensity and 36.6% were classified as responders for disability. The CART model identified impairments in knee self‐perception and knee osteoarthritis severity as the discriminators for pain intensity reduction following exercise. No variables predicted reduction of disability level following exercise.ConclusionsSuch findings suggest that both body perception and osteoarthritis severity may play a role in treatment outcome with exercise. It also raises the possibility that those with higher levels of disrupted body perception may need additional treatment targeted at restoring body perception prior to undertaking exercise.SignificanceRegardless age, sex, body mass index, pain duration, use of medication, knee range of motion, pain catastrophizing and self‐efficacy, participants with knee osteoarthritis who report low levels of body perception disruption (a FreKAQ score ≦ 17) and minimal structural changes (KL grade I) demonstrate significantly better outcomes from exercise therapy than other participants.

Knee-related disability was largely influenced by cognitive factors and disturbed body perception in knee osteoarthritis

“…The effect sizes seen with rehabilitation might also be improved with the inclusion of approaches that target body perception such as sensorimotor training 30 . This would likely most apply those people represented by Cluster 4, the group with the lowest functional capacity, and a recent hypothesis generating study by our group provides support for the idea of an interaction between conservative treatment success and disrupted body perception 31 . While comparison between individual scales is not straightforward, this group appears to have particular problems with knee specific body perception.…”

“But it feels swollen!”: the frequency and clinical characteristics of people with knee osteoarthritis who report subjective knee swelling in the absence of objective swelling

“… 28 , 35 In addition, higher FreKAQ scores at baseline were associated with failing to achieve clinically meaningful levels of pain reduction with a three-month evidence-based education and exercise programme. 54 Furthermore, cluster analysis suggests that disrupted knee perception may explain some of the discrepancy between knee pain–related disability and severity of radiographic findings in knee OA. 37 Item 7 of the FreKAQ (back translated from Japanese: I feel like my knee is bigger [swollen]), specifically asks about knee size and the difference between perception and reality.…”

Validation of the Bath CRPS Body Perception Disturbance Scale

“…The relevance is furthermore stressed by evidence that greater body perception disturbances are associated with poorer outcome (e.g. higher pain intensity, disability, longer disease duration) in CRPS, 39,62 and other pain conditions such as knee osteoarthritis, 42,53 although this is not always found. 13,37 We also looked at predictors of body perception disturbances over time.…”