Hand function of working patients with osteoarthritis of the hands

The population in developed countries is ageing, causing an increase in health
care costs. Prolonged working of the ageing population is one of the elements
that seems necessary to manage these costs. However, with age, some health
issues interfere with this seemingly logical evolution. Osteoarthritis (OA) for
example, a disease with a high prevalence, increases with age. OA is the most
common form of arthritis. In 2006 1,2 million people in the Netherlands suffer
from Osteoarthritis. According to the *Nationaal Kompas Volksgezondheid*, the
prevalence of osteoarthritis in the Netherlands has risen by 50% from 1990 to
2007. From 2007 to 2040 it is expected that this number will increase by
another 50%.
OA is one of the leading causes for loss of work and disability. In populations
of white North Americans and Northern Europeans, about one-third of adults aged
25-74 years have features of radiographic OA involving at least one peripheral
joint group: the most common sites are the hands, followed by the feet, knees
and hips. Osteoarthritis of the hands (OAH) has an important impact on quality
of life in terms of pain, reduced joint mobility and grip strength, activity
limitations and participation. Not much is known about the effects of OAH on
work participation. To know what the impact of OAH on work participation is, it
is essential to know what patients with OAH are capable of doing; what their
functional capacity (FC) is. The FC of patients with OA of the knees and hips
is worse compared to healthy ageing workers. However, little is known about the
FC of patients with OAH that are working. Knowledge on the functionality of
working patients with OAH is needed to be able to develop (vocational)
rehabilitation programs that meet the need of these patients. The aim of this
study is therefore to compare the Upper Limb FC (ULFC) of working patients with
OAH with the ULFC of healthy workers. We expect that this study will increase
the knowledge about the ULFC of working patients with OAH, which should
ultimately lead to improved and sustained work participation of patients with
OAH.

Primary Objective:
Compare grip strength of working patients with OAH with healthy workers.

Secondary Objective(s):
To compare the results of the supplementary tests of working patients with OAH
with healthy workers.
To describe the possible subjective limitations of working patients with OAH,
with two questionnaires.

Forty working patients with OAH that meet the inclusion criteria will be
included. Patients are recruited from the UMCG, MCL and OZG. Sociodemographic
and clinical data like age, gender, ethnicity, height, weight, primary
occupation and *activities involving intensive us of the hands (e.g. sports,
gardening, playing specific musical instruments)*, will be collected. After
inclusion the patients with OAH will be classified according to the ACR
criteria, Kellgren and Lawrence radiologic classification and the severity
level of pain in the previous month on a Visual Analogue Scale (VAS). The
included patients will perform functional tests measuring the ULFC and will
fill out two questionnaires.
The Tests are
1. Grip test: hand strength
2. Perdue pegboard: fingertip dexterity
3. Complete Minnesota dexterity test: gross movement coordination
4. Pinch test: finger strength
5. The overhead lift
6. The overhead work test
7. Repetitive reaching
The questionnaires are:
• FIHOA (Functional Index for Hand Osteoarthritis). Dutch version translated by
Wittoek et al based on the original French FIHOA. Wittoek demonstrated
excellent psychometric properties (test-retest reliability, construct validity
and internal consistency).
• QuickDASH-DLV (Quick Disabilities of Arm, Shoulder and Hand, Dutch Language
Version). This questionnaire includes an optional module about work. The
QuickDASH has excellent psychometric properties shown by Beaton et al,
Gummesson et al and Veehof et al.

Firstly the obtained grip strength will be compared between working patients
with OAH and healthy workers. Secondly the remaining tests will be compared
between working patients with OAH and healthy workers.
The data of the healthy workers will be extracted out of an existing
database(METC protocol 2005/198: Prof. Dr. M.F. Reneman was Principal
Investigator of this study). The used end points and way of obtaining them are
the same for both studies (2005/198 and current study).
It is our intention to match the whole group of working patients with OAH with
the whole group of healthy workers according to known or expected interfering
variables (age, gender and work load). As in study 2005/198 the work load of
test subjects will be determined according to the DOT (Dictionary of
Occupational Titles: http://www.occupationalinfo.org) . The work load is
subdivided in *Sedentary*, *Light*, *Medium*, *Heavy* en *Very Heavy*.
In terms of percentage the number of test subjects in each of the DOT
subdivisions will be made equal in both groups.

This is a cross sectional study that studies the effect of OAH on
functionality. Extended experience with FCE (functional capacity evaluation)
in previous research and clinical care shows limited burden and risks for
participants.
There is a temporary risk of *overuse* of muscles and tendons (as with healthy
people) causing muscle-soreness.

According to the international commission on radiological protection (ICRP) the
estimated risk per subject for 1 x-ray of the limbs and/or joints is
categorized as I: negligable risk of radiogenic cancer(<0.01mSv). In
comparison, according to the * Rijks Instituut Voor Milieuhygiëne (RIVM)* ,
the annual radiation dose in the Netherlands is 2.4 mSv.
The physical discomfort during the radiological investigation is minimal. The
subject will be asked to sit still for the radiological investigations for 1
time less than 1 minute.