Disorders
of joints
As mentioned above, the articular cartilage has no blood supply. It is
nourished by the synovial fluid, the nutrients being produced by the synovial
membrane. The nutrients diffuse through the joint, speeded by the movement of
that joint.
This is the common pathway for all diseases which damage the articular
cartilage. The patient complains initially of pain on movement, and over a
period the joint becomes stiffer and stiffer, gradually fixing in the position
of maximum comfort. The muscles around the joint tend to waste and weakness sets
in, further hampering the patient’s mobility.
Eventually
the joint may actually collapse, the limb shortens and the joint may lose its
normal alignment.
Examination
On inspection the joint may be slightly red and there may be swelling of
the soft tissues, combined with muscle wasting. The limb is held in the position
of comfort and may even be deformed. There may be some heat over the joint, and
careful examination usually reveals at least a small effusion (although it can
be very large). The osteophytes around the joint may be palpable and the joint
line itself is often tender to palpation. Movement will be markedly limited and
crepitus may be both palpable and audible. In osteoarthritis, the knee tends to
fall into varus (bow legs), while in rheumatoid arthritis the knee falls into
valgus (knock knees). The hip tends to flex into internal rotation, and the limb
may actually shorten if there is bone loss.
Treatment
The early treatment of osteoarthritis is aimed at treating the pain and
disability. Nonsteroidal anti-inflammatories may help with the pain.
Physiotherapy should help to maintain mobility. It is said by some that weight
loss improves symptoms. Walking sticks and household aids including a seat in
the shower and handles around bathroom fittings may help the patient to maintain
independent existence.
Once
these nonoperative measures are no longer adequate, joint replacement should be
considered in the hip, knee and the shoulder, as replacement in these joints now
has good long-term results. Even so, in a young active patient, an arthrodesis
should always be considered as an alternative. It is strong. It should give
complete pain relief and can always be taken down and replaced with an
artificial joint if necessary. Arthrodesis should only be considered when a
single joint is affected, otherwise it transfers extra load on to already
compromised joints.
Aetiology
Primary osteoarthritis develops spontaneously without any apparent
predisposing cause.
Secondary
osteoarthritis. This is the final common pathway after damage to the joint
from some other cause. This may be traumatic, sepsis or inflammatory arthritis.
Even repeated bleeds into a joint (as occurs in haemophilia) will cause
breakdown of the articular cartilage, and multiple attacks of gout or pseudogout
will have the same effects.
Underlying
pathology of osteoarthritis
Articular cartilage is a complex structure made up of collagen and
proteoglycan molecules which are highly hydrophilic and create the turgor
pressure of the articular cartilage which gives it its strength and resilience.
The joint surface itself is lubricated by a film of fluid squeezed out of the
articular cartilage by the pressure applied. The first signs of osteoarthritis
appear to be some softening of the articular cartilage (or at least loss of this
turgor pressure) followed by a breakdown in the smooth surface. Microcracks
appear in the
Cardinal
features of osteoarthritis on X-ray
These include:
• loss of joint space;
• subchondral sclerosis;
• osteophytes;
• cysts.
Radiological
features of osteoarthritis (Fig. 26.2).
These include:
• joint narrowing;
• osteophyte formation;
• subchrondral sclerosis;
• cyst formation.
Rheumatoid
arthritis
This is much rarer than osteoarthritis and occurs in a younger age
group. Indeed, it can occur in children, when it is called Still’s disease.
The disease is usually symmetrical and starts in the small joints of the hands
and feet. Women are more commonly affected than men. As each joint becomes
involved, it becomes red, stiff and painful. After a time the disease burns out
in an individual joint, but the damage is done and secondary osteoarthritis now
sets in.
History
Characteristically the patient complains of feeling generally unwell and
the painful joints are most painful and stiff early in the morning when the
patient first gets up. This is in contrast to osteoarthritis where the joint
is usually most painful in the evening after a long day’s activity.
Examination
The skin over the joints is red and glassy. The soft tissues are swollen
and in the late stages the joints may be subluxed or even dislocated. The skin
may be hot to touch and the swelling of the soft tissues is often as much
synovial thickening as a synovial effusion. The joint therefore feels doughy
rather than having a simple effusion. The bones do not usually have palpable
osteophytes. Normal movement is markedly diminished but the joint may be
grossly unstable as the ligaments around the joint may have stretched, or the
joint surface itself may have collapsed.
Treatment
The bulk of treatment for rheumatoid arthritis is nonoperative.
Nonsteroidal anti-inflammatories, analgesics and immunosuppressants, including
steroids, are routinely used,
Pathology
A pannus of inflammatory tissue spreads from the margin of the joint,
across the articular cartilage, creating inflammation in the joint and
destroying the articular cartilage. The bone around the joint becomes
osteoporotic, possibly because of hyperaemia, and because of disuse. In the late
stages the joint may collapse completely.
Charcot’s
joints — neuropathic joints
Any joint which has lost its nerve supply seems to he susceptible to a
particularly aggressive form of arthritis. The condition was originally
described with tertiary syphilis but can in fact occur whenever the sensory
supply to a joint is affected. There is massive joint destruction combined with
new bone formation producing a very disorganised joint in a patient who is
complaining of surprising little pain. Once seen it is never forgotten.
Nonspecific
seronegative arthritis
Not all arthritis is either osteoarthritis or rheumatoid arthritis.
Acute onset of pain in joints can occur secondary to a viral infection or indeed
for no known cause. The treatment is symptomatic with anti-inflammatories,
splints and physiotherapy.
Chondromalacia
patellae — anterior knee pain
This condition occurs in adolescents, particularly girls, and may
initially be brought on by a blow to the knee. The patient complains of severe
pain in the knee which is worse going down stairs and if they are obliged to sit
still for any length of time. After this period of rest any attempt to move the
knee is extremely painful and may cause them to collapse. On examination there
is surprisingly little to see. There is no redness or swelling and there may be
very little thickening of the synovium and no effusion. Range of movement is
good but there may be crepitus from the patella. The synovium around the patella
is tender to palpation.
This condition can also be caused by maltracking of the patella but in
the majority of cases there is no obvious cause to be found.
Luckily,
the condition is usually self-limiting and treatment is symptomatic using
nonsteroidal anti-inflammatories, splints and physiotherapy and trying to keep
the patient as mobile as possible within the limits of pain.