OSTEOARTHRITIS

WHAT IS OSTEOARTHRITIS?

Osteoarthritis is a degenerative joint disease.

Caused due to mechanical stress and covert low grade inflamatory process.

Due to excessive mechanical stress there is increased in demand from factors responsible for repair mechanism. Initially this repair mechanism repairs as it normally should but then it becomes insufficient to repair with same mechanism so it starts compensatory mechanism where in, it tries to maintain structural aspect but at cost of quality of structural components which again due to its inferior quality gets damaged soon further due to prolonged regular mechanical stress these damages gets accumulated even further and now even compensatory mechanism fails to keep up with the amount of damage that’s been done , this starts erosion of the cartilage and the underlying bone and there is general degeneration of joint.

WHAT ARE THE RISK AND CAUSATIVE FACTORS FACTORS OF OSTEOARTHRITIS?

  • Mechanical injury like trauma causing damage to joint or any of its component useful in maintaining strenght structure gait and support to joint.
  • Mechanical stress due to different length of either legs
  • Mechanical stress due to neurological muscular disorder of muscles supporting that particular joint
  • Those who never had habit of running or jogging during their childhood or young age if suddenly starts running in excess on later age; or running along with an injury cuases severe mechanical wear and tear injury to joint.
  • Abnormal body gait and habitual abnormal postures
  • Genetics and hereditary
  • Hormone levels especially sex hormones
  • Metabolic syndrome and obesity( debated as its not the weight thats causing mechanical damage but rather its fats thats responsible to cause metabolic disorder contributing to osteorthritis)
  • Diet and Lifestyle
  • Prolonged regular mechanical stress and insufficient self repair causing accumulation of damages and later resulting into prolonged inflamation causes osteoarthritis
  • Prevailing condition in body like metabolic disorders ; autoimmune diseases ; joint infections ; congenital joint anomaly certain syndromes like marfan syndrome ; elher danlos syndrome; inflamatory diseases like lyme’s disease perthe’s disease

PATHOGENESIS OF OSTEOARTHRITIS

Chondrocytes are responsible to maintain elastic and tensile strength of cartilage by producing collagen and extracellular matrix which maintains hydration by compressive force driving water out and hydrostatic and osmotic pressure drawing water in.

Constant damage to cartilage puts extra load on chondrocytes ;if they aren’t able to repair the damage by producing sufficient collagen and extracellular matrix ; then they start producing different type of collagen just to maintain the structure as far as possible but then this collagen has a different character of retaining more water then the former which spoils the elastic and tensile strength of cartilage as a whole. This further damages the cartilage to the point where it starts disintegrating and shedding off in synovial space which puts extra load on synovium to clear it off for which synoviocytes triggers inflamatory response and synovitis and general mild inflamatory process in joint which gets prolonged due to constant mehanical stress and accumulated damages and finally inflamatory products accumulates damaging joint even further eroding cartillage and bone causing fibrillations and also reduced bone mineral density at site is observed (causation is in debate); finally there is general degeneration of joint leading to pain inflamation and loss of regular function of the affected joint.

WHAT ARE SYMPTOMS OF OSTEOARTHRITIS?

  • Low grade inflamation and degeneration causes pain due to which there may be loss of range of movement of a joint along its axis in varing degrees from mild to severe.
  • This loss of ability of movement further causes dysuse atrophy of muscles related to that particular joint and due to degenerative changes the joint becomes wider which gives typical lean muscle and wide joint looks;like heberden’s nodes and bouchard’s nodes in fingers
  • Osteoarthritis particularly involves weight bearing joint and joints more prone to mechanical stress like knee joint; lumbar spine cervical spine hip joint joints of fingers and less commonly other joints like ankle joint shoulder joint etc
  • It may present in one joint or in multiple joints at a time.
  • Exertion and motion aggravates the complaints and rest ameliorates the complaints.
  • Morning stiffness of affected joint is present in majority cases  though not a specific symptom.
  • Aggravation in cold climate ; high humidity; low atmospheric pressure is seen in many cases tough not consistent every-time.
  • Crepitation on movement or pressure are observed in affected joint.
  • Surrounding muscle spasms and when vertebral bodies are affected the spinal nerve corresponding to it may get compressed leading to spasms paraesthesia myalgia and cramps to correrponding musscle the affected nerve supplies.
  • Joint effusion, especially of knee joint are seen; not too infrequently.

DIAGNOSIS OF OSTEOARTHRITIS

In most cases sufficient clinical evidence supports the diagnosis but an X ray is required not only to reconfirm diagnosis but also to evaluate to amount of damage within as pain and other clinical symptoms are not indicator of the amount of damage within; in many cases we may also need to exclude other conditions for which further related investigations should be done.