Neuropathic pain and Proprioceptive Acuity in Knee osteoarthritis

Pain, next to limitation of function, is the most prominent symptom in patients
with knee
osteoarthritis (OA). From research we know that there is a possible
cross-sectional relationship between knee pain and impaired proprioceptive
accuracy, however evidence is
conflicting. Proprioception is defined as *the perception of movement and
position of body segments in relation to each other without the aid of vision*
It seems to be a key element in maintaining proper knee-function, as it
protects the knee against possible injurious movements via reflex responses,
stabilize the knee during static posture and coordinates precise knee joint
motions.
To date, the causes of impaired proprioception within knee OA patients remain
unclear. The general hypothesis is that mainly dysfunctional mechanoreceptors
and muscle weakness may lead to impaired proprioceptive accuracy. However, to
our knowledge no strong evidence was found to confirm this hypothesis. Another
hypothesis is that nociceptive input may overrule proprioceptive input, so
impairing proprioceptive accuracy. Furthermore there are indications that
proprioception could be impaired due to a more general sensitized state of the
body, called central sensitisation (CS).
As stated studies about the relation between knee pain intensity and
proprioceptive accuracy are conflicting, for both motion and position sense. A
recent review stated that six cross-sectional studies found an association,
where five studies did not. A recent study suggested that a relationship
between catastrophisation of pain rather than the intensity of pain could
affect performance on proprioceptive tests, so taking into account pain
catastrophizing seems to be essential. Also none of these pain-related studies
investigated the association of neuropathic pain symptoms and proprioception.
Over the past decade, it has become clear that OA pain symptoms varies among
patients with knee OA, from nociceptive pain to neuropathic pain . Multiple
studies showed that about 20-40% of the knee OA patients experience significant
neuropathic pain symptoms. These symptoms may be explained by OA-induced
changes in the biochemical environment around peripheral joint nociceptors and
joint structures, combined with complex OA-related somatosensory changes (like
CS).
It has never been studied whether these neuropathic pain symptoms are
associated with impaired proprioception. It is possible that due to the
OA-induced changes, proprioceptive accuracy becomes impaired in a subset of
patients who are experiencing neuropathic pain symptoms. This information may
provide additional support for the need to better customize conservative OA
treatment, as treatment of neuropathic pain symptoms could theoretically lead
to better proprioceptive accuracy. Therefore the aim of the present pilot study
is to gain first insight into the association between knee proprioception and
joint related neuropathic pain symptoms in patients with symptomatic knee OA.

To gain first insight into the association between knee proprioception and
joint related neuropathic pain in patients with symptomatic knee OA.

Primary Objective:
To study the association between joint related neuropathic pain (measured with
the modified-painDETECT questionnaire) and proprioceptive acuity (motion sense,
measured by the threshold to detect passive motion [TTDPM]). Associations will
be adjusted for the relevant covariates age, sex, and functional lower limb
muscle strength (FTSST).

Secondary Objectives:
1) Study the association between joint related neuropathic pain (measured with
the modified-painDETECT questionnaire) and proprioceptive acuity (position
sense, measured by the Mr Cube method). Associations will be adjusted for the
relevant covariates age, sex, and functional lower limb muscle strength
(FTSST).

2) Study the association between pain catastrophizing and proprioceptive
acuity, both motion and position sense. Associations will be adjusted for the
relevant covariates age, sex, and lower limb muscle strength (FTSST).

Pilot study with a cross-sectional design. This observational study will
include patients with symptomatic osteoarthritis (OA) of the knee.

Not applicable