Partial Knee Replacement: When One Compartment Is Affected

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 survivorship of newer implants, taking an average value, is more than 20 to 25 years, though there's a range. To measure success there's a prerequisite: we presume the patient has taken care of the joint, followed the precautions, physical therapies and exercises they've been told — the value I've mentioned is the average assuming that's been taken care of.

It's a permanent, non-removable procedure — it doesn't need to be removed. The follow-ups: the first milestone is at two weeks, to remove the stitches, then six weeks post-surgery, then three months, six months, and then annually.

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.

A procedure that replaces only the damaged compartment of the knee rather than the entire joint, used when X-rays show single-compartment disease with the rest of the knee relatively preserved.

Patients with damage spread across multiple compartments of the knee; they are usually better served by total knee replacement.

Because less bone and tissue is disturbed, patients can often expect a smaller surgical footprint and a comparatively simpler recovery.