Muscle strength measurements of the Hand - Handen Team Zeeland

Ton A.R. Schreuders, JW Brandsma, HJ Stam
manufactured a new device called the
Intrins-o-meter. 20 In 1997 he reported a
study in 48 patients with ulnar nerve
compression. 21 Rosen et al. noted that
assessing muscle function using the
Intrinsi-o-meter was difficult due to the
extremely small forces, and the instrument
was difficult to handle and read. They
suggested using MMST and grip strength
measurements to evaluate nerve function.
Interestingly they found a poor recovery of
the intrinsic muscle strength with the
Mannerfelt instrument and good grip
strength recovery.
22 23
Several others have developed
instruments mainly to assess the
abduction of the thumb. 24-26 Some needed
a specially constructed jig, e.g. to measure
wrist, finger (metacarpo-phalangeal joints)
and thumb extension strength. 27
Rotterdam Intrinsic Hand Myometer
(RIHM) (Figure 3)
In 1995 inventories were made at
our department to establish which clinical
evaluation instruments were available to
assess the outcome after peripheral nerve
surgery. Three methods were often used
to assess the recovery of muscle strength:
MMST and grip and pinch strength
dynamometers.
Having encountered several
patients with good grip strength but poor
recovery of the intrinsic muscles strength,
we questioned whether grip strength
measurements were appropriate. We
acknowledged the need for a
dynamometer to measure the intrinsic
muscles in isolation. Such a dynamometer
should be easy to handle, e.g. portable
and with an ergonomical design. It should
also have the possibility to measure the
opposition force of the thumb. Reliability
should be good with acceptable
measurement error making it possible to
detect reasonably small changes in
muscle strength.
Figure 3 RIHM dynamometer
The Intrinsic Muscles
of the Hand:
Function, Assessment and
Therapy principles
Introduction
There have been many valuable
studies concerning the anatomy 28-30 ,
mechanics, 2 31 32 and architectural
design, 33 of the intrinsic muscles of the
hand. Understanding the mechanics of
human dexterity requires an appreciation
of the kinetic chains that comprise the
hand, and the intricate interplay of
muscles and ligaments that control its
movements. 2 In these chains, the intrinsic
muscles of the hand are of paramount
importance for efficient hand function. 33
There is a considerable decrease
in functional efficiency in hands with loss
of the intrinsic muscles function, often
referred to as the clawhand or intrinsic
minus hand (Figure 1). 34-36
A comprehensive analysis of hand
function should include assessment of the
strength and length of the intrinsic
muscles. This will provide important
information and assist the assessor in e.g.
determining nerve function, deciding which
muscles need to be strengthened, what
splint is needed, what surgery needs to be
considered (tendon transfer), etc.
Although assessment of muscle
strength and length are important
elements of hand function other functions,
e.g. mobility, sensibility and central
properties of the brain, are equally or more
important for hand function. The latter
4