How we grade knee arthritis

The KOGS grading system, in plain English.

KOGS is a simple way to grade knee arthritis from Stage 1 (early wear) to Stage 4 (severe). Dr Oosthuizen developed it to match every patient with the right next step — non-surgical care, a partial knee replacement, or a full knee replacement.

Stage 1

Early wear

01

What we see

•Mild cartilage thinning on X-ray
•Pain only with activity
•Full range of movement

Usual next step

Treated without surgery — weight management, physio, posture correction, injections.

Stage 2

Wear on one side of the knee

02

What we see

•Arthritis in one part of the knee only
•Ligaments still intact
•Leg alignment normal or correctable

Usual next step

Usually the ideal time for a partial knee replacement.

Stage 3

Wear spreading across the knee

03

What we see

•Arthritis in two or more parts of the knee
•Slight bowing of the leg
•Everyday activities becoming difficult

Usual next step

Full knee replacement or a staged plan is considered.

Stage 4

Severe arthritis

04

What we see

•Bone-on-bone on X-ray
•Clear bowing of the leg
•Constant pain, even at rest

Usual next step

Full knee replacement with careful planning of leg alignment.

Partial vs full knee replacementStage 2 knees are often suited to a partial replacement — see how the two operations compare.Your knee-replacement journeyWhat happens after grading — consultation, surgery and recovery, step by step.

Have your knee graded

Send in your X-rays or scans and Dr Oosthuizen will grade your knee using the KOGS system.

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Dr Oosthuizen consults Mon & Thu at JSH and Tue at Wilgeheuwel (mornings only). Please suggest a date within these sessions.

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Next step

Not sure which KOGS grade you're at?

Book a consultation and Dr Oosthuizen will look at your X-rays and tell you clearly where your knee sits — and what the best next step is.

Mon·JSH·06:30 – 10:00
Tue·Wilgeheuwel·06:30 – 10:00
Thu·JSH·06:30 – 12:00

Book Consultation Try the Knee Check

Medical Alert · Emergency Care

Orthopaedic emergencies outside consulting hours

If you experience an orthopaedic emergency outside of consulting hours, please report immediately to the Casualty Department at either Johannesburg Surgical Hospital (JSH) or Life Wilgeheuwel Hospital for assessment and treatment. The casualty doctors will provide the necessary emergency care and arrange specialist orthopaedic referral if required.

Life-threatening emergency? Call 10177