The knee joint has three separate functioning compartments. The medial or inner compartment, the lateral or outer compartment and the anterior or kneecap compartment. Arthritis usually starts in the medial compartment in about 90% of cases whereas the other two compartments remain relatively normal for many years. A unicompartmental (UKR) replacement replaces one of these compartments. A total knee replacement replaces all three compartments. ( A picture here showing the difference would be helpful )

Somewhere between 30 to 50% of patients presenting for knee replacement surgery will be potentially suitable for an Oxford knee. Do ask your surgeon what type of arthritis you have and whether you are suitable for a UKR.

Early advantages: Many patients can be treated as daycase surgeries where they are able to return home within 4-6 hrs after surgery. The recovery is usually much swifter compared to a total replacement. Late advantages: At 5 year follow-up of a Randomised Control Trial (The most scientific method of comparing the merits of one treatment verses another) comparing UKR verses total knee replacement (TKR), every outcome measure (speed of recovery, time to regaining motion, how the knee feels, risk of reoperation etc etc) favoured the UKR and the failure rate (the need to redo the replacement) was no different at 5 year review.

Most patients can go home within 4-6 hrs of surgery and are fit to drive within 3 weeks of surgery. Most patients are reasonably happy by six to 8 weeks of surgery and most no longer require strong pain relief. 80% of the recovery will take place in the first 2 months but the final 20% will take at least 6 months.

Most UKR now in use have 90% survivorship at 10-15 years. In other words, there is a 9 in 10 chance that the patients implant will still be functioning at 15 years after surgery without the need for further replacement surgery.

Our 20 yr results show that 6.6% of patients will eventually get symptomatic arthritis of the outer compartment requiring operative intervention. We now routinely offer another UKR to the outer compartment. We find the original inner UKR invariably continues to function very well and all we need to offer is addition of a UKR on the outer side.

Our results show that those patients seeking to be very active after their UKR are able to get back to high activity levels. Nearly all golfers return to their sport, and many patients get back to skiing and tennis. These patients are our happiest patients because they have been able to return to their chosen sports and interestingly they have the best implant survivorship. Certainly high activity does not seem to obviously damage the implant or negatively affect the results.

Your GP (General Practioner) will know the local Knee Surgeons and most of these surgeons will have websites giving their interests and areas of expertise. It is always worth asking your surgeon how many UKR surgeries he/she performs per year. The other useful metric is to ask their usage (percentage of knee replacements that are UKR). Increasing evidence suggests that they should be performing at least 20% of their replacements as UKR. The higher the usage up to 50% the better their results are likely to be. Increasing expertise is the key to obtaining good results.