Classification systems are used by doctors to assess the extent of arthritis in the joint.
A number of elements are deemed important when assessing what interventions might be helpful in trying to contain the arthritic process surgically:
- the size of the area of cartilage destruction
- the depth of the damage
- whether or not it is contained in one compartment
- the degree of functional disability
- the patient's age and expectations
Structural classifications record objectively the extent and depth of the joint cartilage damage. This helps the surgeon to follow the progression or improvement of the structural damage. A commonly used classification is the Outerbridge Classification:
- Grade 0: normal cartilage
- Grade I: cartilage with softening and swelling
- Grade II: partial-thickness defect with fissures on the surface that do not reach the underlying bone or exceed 1.5 cm in diameter
- Grade III: fissures to the level of underlyingbone in an area with a diameter more than 1.5 cm
- Grade IV: exposed underlying bone.
Functional classifications reflect the degree of disability suffered by the patient with joint damage, eg Lysholm score, WOMAC score.
Other classification systems
- Insall classification
- Goodfellow classification
- Casscells classification
- Ficat & Hungerford classification
- Cincinnati Knee Rating System
- SFA system
- ICRS system
- Hunt classification