What Is Osteoarthritis? Understanding Joint Damage and Its Causes

In athletes the demand of activity is much more than the normal population — jumping, contact sports — and there's wear and tear involved in the artificial joint over time. We generally tell patients not to jump or run, for the sake of the longevity of the implant — the more activity, the more wear, and the more chance of needing revision surgery. First we tell them to change their activity level if possible; if that's not possible, there are certain implant variations available, like hip resurfacing or metal-on-metal implants, which can be offered if it's mandatory for the athlete to continue their sport — though ceramic implants are not good for them because of a higher chance of breakage.

For infection: understand the kind and duration of it. If it's acute, be very aggressive — antibiotics alone won't suffice, don't hesitate to go inside and clean the joint, with multiple debridements till it feels clean; antibiotics work as an adjuvant, not the primary therapy. In the knee you can also change the polyethylene component, put a drain for three to five days, give antibiotics. But if it's longstanding — more than a month — you may need staged revision surgery: stage one, remove the implant and put an antibiotic spacer, monitor for six weeks until infection markers are normal and skin has healed, then stage two, the revision total replacement. On MRI: all joint replacements can have an MRI done, provided the implant is well fixed — if it's unstable, MRI may not be a good idea, but if the joint is stable, MRI can be done using implant-specific coils that neutralise the implant artefact.

This is a common perception, actually — in the first six to eight weeks we don't want the patient to bend beyond 90 degrees, talking about hip replacements, to reduce the chances of dislocation so the capsule heals well. That's the 90 degree rule for hip replacement.

KL is just the WHO classification of osteoarthritis — it's not very good. Diagnosis is a clinical one: patients complaining of typical pain — pain while walking, pain while taking stairs, pain while sitting cross-legged — with definitive tenderness on the joint line, is almost confirmatory. That's the real gold standard, not the X-ray. X-ray is the baseline test, but it's not the criterion for deciding which patient should undergo surgery — a grade four KL arthritis patient with minimal pain treated well with physical therapy may not be a candidate for joint replacement, while a grade three patient who has tried all conservative measures without relief could be. It's a paradox, so X-ray grading alone isn't the gold standard. On location: for osteophytes, the location of weight-bearing matters more, but for me it's typically joint space reduction that matters most, because it indirectly shows the articular cartilage is gone — and that's irreversible.

Medical therapy is the first line of treatment — it should be tried first, and once pain is not relieved with medical therapy and physical therapy, and the patient is having difficulty in activities of daily living, then the patient becomes a candidate for surgery.

The cushioning cartilage gradually breaks down, the joint space narrows, bone spurs form, and the joint becomes painful and stiff.

Under the microscope, healthy cartilage is well organised, smooth and hydrated, while arthritic cartilage is dehydrated and disorganised; to the naked eye, healthy cartilage looks glistening and smooth, while arthritic cartilage is rough and eroded.

It has multiple contributing factors rather than a single cause, including physical inactivity, obesity, poor diet, metabolic syndromes and joint injuries.

No. The transition from a healthy to an arthritic joint also involves changes at the molecular and biochemical level, not just changes in anatomy.