The Skeletal System
Osteoarthrosis (Osteoarthritis, Arthrosis or Degenerative Joint Disease) is
not a single disease, but the end-result of a variety of patterns of joint
failure. To a greater or lesser extent it is always characterised by both
degeneration of articular cartilage and simultaneous proliferation of new
bone, cartilage and connective tissue. The proliferative response results in
some degree of remodelling of the joint contour. Inflammatory changes in the
synovium are usually minor and secondary.
By the age of 65, 80% of people have radiographic evidence of
osteoarthrosis although only 25% may have symptoms. Males and females are both
affected but osteoarthrosis is more generalised and more severe in older
women. Cold, damp climates are associated with more symptoms but not with
greater radiological prevalence.
Osteoarthrosis is classified as primary if the aetiology is unknown and
secondary when degenerative joint changes occur in response to a recognisable
local or systemic factor.
These factors might be:
- traumatic (e.g., prolonged overuse of joints as in certain occupations
such as pneumatic drill workers or in athletes, after intra-articular
fracture and imperfect mending of fractured bones)
- developmental abnormalities are believed to be of major importance in the
aetiology isolated osteoarthrosis of the hip in the vast majority of cases
- inflammatory (such as rheumatoid arthritis or bacterial arthritis)
- haemophilia (inherited defect of blood clotting) where frequent bleeding
episodes into the joints can lead to gross deformation
- metabolic diseases lead to degeneration of cartilage by very different
mechanisms (e.g., haemochromatosis - accumulation of iron, Wilson's disease
- accumulation of copper)
- many other more rare disorders
Hyaline cartilage in the joints is an avascular structure composed of 95%
water and extracellular cartilage matrix and only 5% chondrocytes (cartilage
cells). Cartilage health and function depend on compression and release of
weight bearing and use; e.g., compression pumps fluid from the cartilage into
the joint space and then into venules, whereas release allows the cartilage to
re-expand and absorb necessary nutrients. It is possible that repetitive
loading or other unknown factors cause fatigue fracture of the collagen fibre
network in the cartilage. As the process evolves, the cartilage surface
becomes cracked and deep clefts appear, which can lead to microfractures and
increased production of the subchondral bone. Proliferation of chondrocytes
and osteoblast eventually forms characteristic spurs composed of new bone and
cartilage (osteophytes or more correctly osteochrondrophytes).
Disease pathology includes roughening pitting and irregularities of the
hyaline cartilage surface, proceeding to gross ulceration with focal and then
diffuse areas of complete loss of cartilage, leaving only exposed bony
Clinical features: < BACK TO TOP >
- The joints most frequently involved are large weight bearing joints of the
spine, hips and knees, and the disease is confined to one or only a few
joints in the majority of patients.
- The symptoms are gradual in onset, initially with intermittent aching pain
provoked by the use of the joint and relieved by rest.
- As the disease progresses, movement in the affected joint becomes
increasingly limited initially as a result of pain and reflex muscular
spasm, but later because of capsular fibrosis, osteophyte formation and
remodelling of bone.
- There may be repeated effusions into joints especially after minor twists
or injuries with associated swelling.
- Crepitus (crackles, grating noise) may be felt or even heard during joint
- Associated muscle wasting caused by reduced mobility is an important
factor in the progress of the disease, as in the absence or normal muscular
control the joint becomes more prone to injury.
- Osteoarthrosis of the cervical and lumbar spine (spondyloarthrosis) may
lead to compression of the spine nerves (radiculopathy) presenting with pain
and numbness radiating along the course of the brachial plexus nerves (down
the arms) and the sciatic nerve ( down the buttock and the posterior aspect
of the leg to below the knee).
- In certain patients bony enlargement or the distal interphalangeal joints
(heberden's nodes) and proximal interphalangeal joint (Bouchard's nodes) may
- Pathological changes of osteoarthrosis are irreversible.
Diagnosis: < BACK TO TOP >
- The blood count and ESR are characteristically normal, which helps to
distinguish this condition from rheumatoid arthritis.
- Synovial fluid is clear and viscous with low inflammatory cell
count, which argues against significant inflammation.
- Radiographs show loss of cartilage (joint space) and formation of
- Subchondral bone sclerosis (hardening), bony remodelling and cyst
formation are seen on X-ray in more advanced disease.
Management < BACK TO TOP >
- Periods of rest and avoidance of unnecessary trauma and physical stress to
affected joints are essential.
- Adequate footwear, weight loss in obese patients with osteoarthrosis of
the knee or hip, provision of suitable walking stick and change of
occupation could help.
- NSAIDs can be given to relieve pain and stiffness but they are not s
effective as in rheumatoid arthritis.
- Periarticular or intra-articular corticosteroid injections in
osteoarthrosis of large joints (e.g., knee) are indicated significant
inflammation and joint effusion are found; oral corticosteroids are not
- Hyaluronic acid, a normal physiologic component of synovial fluid, has
proven effective if given by intra-articular injection; oral preparations
containing glucosamine and chondroitine sulphate may also provide some
relief if taken regularly long enough.
- Hip or knee arthroplasty (prosthetic joints) in patients with advanced
disease is the only means to preserve patients mobility when conservative
Prognosis < BACK TO TOP >
Dr Zoran Pletikosa)