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Cycle of Deformity
Common to RA
Common to OA
Important Reminders |
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The resulting hand deformities
involved in arthritis is one of the most devastating
symptoms which have functional and psychological
implications. Seeing your fingers getting deformed
progressively is an alarming experience. Oftentimes a
patient wonders, "How much worse can this be?" Aileen, one
of my younger patients suffering from rheumatoid arthritis,
said, "I feel so self-conscious about my hands. I try to
hide them in my pockets all the time." John, another patient
who works as a construction worker, observed that it gets
harder for him to grasp objects at work, "My fingers easily
buckle".
Unfortunately, whether you are doing self-care,
housekeeping, or work related tasks, your daily grasping
activities make use of directional forces that are deforming
to your wrist and finger joints. This is particularly true
for persons who already have beginning or visible joint
swelling. One thing to remember about swollen joints is that
they are weak and unstable. Daily resistive grasping
activities use shearing forces that can aggravate joint
deformities. For example, opening a door requires twisting
or swaying your wrist and fingers to the side which
facilitates what is called "Ulnar Drift", a typical
arthritic deformity. Prolonged resistive pinching, like
holding a pen to write, facilitates a zigzag deformity
common to the rheumatoid thumb. |
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Arthritic hand deformities develop as a
result of prolonged joint inflammation.
Tendons and ligaments which occupy a certain
position around a joint are distended and
forced out of place by the swelling, causing
irregularities in tendon pull and ligament
support. Tendons are like "rubber bands"
connecting a muscle to a joint. As a muscle
contracts, it pulls on a tendon and creates
movement on a joint. Ligaments, on the other
hand, connect one bone to another providing
support for proper joint alignment. Once the
alignment and integrity of these supporting
structures are affected, the joint "buckles"
and deformity ensues. Furthermore, since the
joint is unstable, the deformity is further
facilitated by the pull of a misaligned
tendon which forces the joint to move at
abnormal directions particularly on
resistive hand use. Affected joints give way
and the result is a process of progressive
joint deformities. |
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Let us
begin to discuss the most common types of deformities that I
see in the clinic. This may not be a comfortable topic to
discuss with you, but again, I believe the earlier you
recognize it, the more you can prevent it from getting
worse. Not all patients suffer from severe deformities. By
being familiar with the deformity patterns involved in
arthritis, you can begin to use joint protection techniques
to daily tasks that you have identified as having the
potential to aggravate these deformity patterns even more.
Arthritic deformities follow a certain pattern. A good way
to describe this is that successive joints "buckle" and
follow a zigzag deformity. The most common types of
deformities that I see in the clinic are the following (I
have marked each type of deformity with a yellow line to
emphasize the zigzag deformity pattern): |
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1. Wrist Radial
Deviation
The wrist contains two rows of
small pebble like bones called carpal bones which are held
together by ligaments. The proper alignment of these bones
to each other is critical for proper wrist movement and
function. Prolonged swelling on the wrist can cause carpal
ligament instability. This can lead to the displacement of
one carpal row over the other causing a position shift, or
deviation of the wrist towards the thumb side. |
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2.
Metacarpo-Phalangeal (MCP) Ulnar Deviation
This is the most common
deformity seen in RA. Prolonged swelling on the knuckles may
cause destruction of the supporting ligaments at the base of
the joint and lateral displacement of the finger tendons.
This causes the four fingers (index to small fingers) to
drop down from the knuckles and sway to the side towards the
small finger. The misaligned flexor tendons further pull or
sway the fingers to the side when grasping. |
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3. Boutonnière
Finger Deformity
Imbalance of ligament pull and
laxity on the finger joints due to prolonged swelling can
cause a collapse or zigzag deformity on the finger
consisting of hyperextension of the knuckle, flexion of the
middle joint, and hyperextension of the last joint (close to
finger nail). |
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4. Swan Neck
Finger Deformity
This zigzag deformity pattern
on the finger is the opposite of the boutonnière deformity,
where the middle joint of the finger hyper-extends and the
last joint flexes. This zigzag deformity pattern on the
finger is the opposite of the boutonnière deformity, where
the middle joint of the finger hyper-extends and the last
joint flexes. This happens when the prolonged joint swelling
and resulting joint laxity starts at the palmar side of the
middle finger joint. |
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5. Thumb
Z-Deformities The
thumb may follow either a boutonnière or swan neck deformity
pattern. The boutonnière is the most common thumb deformity
in RA where the first thumb joint bends forward and the last
joint hyper-extends. Z deformities of the thumb eventually
lead to a narrowing or contracture of the web space making
it difficult to open the thumb for grasping or pinching. |
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1. Bouchard's
Nodes
The bony enlargement of the
middle joint of the fingers due to formation of osteophytes
(bony outgrowth). |
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2. Heberden's
Nodes
The bony enlargement of the
last joint of the fingers (close to finger nail) due to
formation of osteophytes. |
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3. Angulation
deformity of finger joints.
The middle or last joints of
the fingers sway to the side due to uneven cartilage and/or
joint surface degeneration. This may be aggravated by the
shearing forces of daily grasping or pinching tasks. |
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4. Mallet
Finger Deformity
Flexion deformity of the last
joint of the fingers due to abrasion of the extensor tendon
insertion over a sharp bony outgrowth or osteophyte. |
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5. Carpo-metacarpal
(CMC) joint enlargement and subluxation.
Osteophyte formation at the base
of the thumb close to the wrist (first thumb joint) produces
a characteristic "shoulder" or "squaring" of the joint. This
bony enlargement at the base of the thumb may affect
movements on the other thumb joints depending on the
location of the osteophyte. |
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1. Arthritic
deformities are permanent and progressive in nature.
2. Early control of
joint inflammation through effective medication and
use of joint protection techniques is vital in
preventing deformities.
3. Because
arthritic joints are weak and unstable, the
repetitive stress involved in daily resistive hand
use -- such as opening a jar, may aggravate your
arthritic deformities.
4. Using joint protection techniques to your
daily grasping tasks is important in preventing
aggravation of deformities.
5. Using assistive devices that minimize the
deforming forces of daily hand use help in deformity
prevention.
6. Using hand splints that position weak
joints at neutral or anti-deformity positions -
where tendons, ligaments and other joint tissues are
placed at a balanced position (not overstretched) -
may prevent aggravation of deformities on the long
run. These splints are usually worn at night.
7. Be proactive, frequently monitor your hands
for beginning signs of joint inflammation and
deformity patterns so you can prevent them from
getting worse by early use of joint protection
techniques.
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>>
Back to top of page |
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By being aware that certain
grasping activities accentuate the deformity patterns
involved in arthritis, you can avoid aggravation of
deformities by conscientiously applying joint protection
techniques to "high risk" tasks.>>next
page |
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© Copyright 2008, Hand Arthritis Info Center. All rights reserved
