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Articular Cartilage Rating Systems
Introduction
Many grading systems have been proposed to classify lesions of the articular cartilage in the knee joint at arthroscopy; however, only a few are commonly used in modern orthopedic literature ( Table 44-1 ). The systems published in the 1960s and 1970s introduced grading schemes for lesions located only in the patellofemoral joint and documented the most frequent locations of damage in this compartment. The first of these patellofemoral classification systems, proposed by Outerbridge, remains one of the most commonly used schemes to grade lesions located in all three compartments of the knee (patellofemoral, medial tibiofemoral, and lateral tibiofemoral). As arthroscopic and imaging techniques have evolved, a few investigators and societies (French Society of Arthroscopy, International Cartilage Repair Society [ICRS] ) have proposed articular cartilage rating systems which are far greater in sophistication in classifying lesions (described later). These systems are useful for formal clinical investigations to determine the etiology and prognosis of partial and full-thickness cartilage injuries after various knee injuries and to determine the indications and outcomes of cartilage resurfacing procedures such as mosaicplasty and autologous chondrocyte implantation (ACI). This is especially true when practical and financial constraints limit or prohibit the use of advanced magnetic resonance imaging (MRI) or objective measurements done at surgery. These techniques are not discussed in this chapter, although we recognize their significance in this area. This chapter focuses on the most commonly used arthroscopic articular cartilage rating systems today.
TABLE 44-1
Commonly Used Articular Cartilage Rating Systems
| Rating System | Surface Description of Articular Cartilage | Lesion Size (Diameter) | Location | Comments |
|---|---|---|---|---|
| Outerbridge | 1 = Softening and swelling 2 = Fragmentation and fissuring 3 = Fragmentation and fissuring 4 = Bone exposed |
1 = none 2 = ≤0.5 inch 3 = >0.5 inch 4 = none |
Usually starts on medial facet of patella; later extends to lateral facet and then whole patella. Concomitant femoral condylar lesions usually not present; may have occasional “mirror” lesion on intercondylar area; erosion upper border medial femoral condyle. | Rating developed for patellar lesions only. Hypothesized majority initiated by pressure or friction of patella in high knee flexion angles. |
| Cincinnati Knee Rating System | 1 = Cartilage surface intact 1A = Definite softening with some resilience remaining 1B = Extensive softening with loss of resilience (deformation) 2 = Cartilage surface damaged; cracks, surface blisters, fissures, fibrillations, fragmentations 2A = Less than half thickness 2B = Half thickness or greater 3 = Bone exposed 3A = Bone surface intact 3B = Bone surface cavitation |
<10 mm, ≤15 mm ≤20 mm ≤25 mm >25 mm |
Patella A = Proximal third B = Middle third C = Distal third Trochlea Medial and lateral femoral condyles A = Anterior third B = Middle third C = Posterior third Medial and lateral tibial plateaus A = Anterior third B = Middle third C = Posterior third |
Also record degree of knee flexion where the lesion is in weight-bearing contact. Scoring system for lesions provided for research purposes (see Table 44-2 ). |
| International Cartilage Repair Society | Four grades for chondral defects, four types for osteochondral defects (see Table 44-5 ) | Record in mm | Mapping system (see Fig. 44-7 ) Medial, lateral femoral condyle Trochlea Medial, lateral tibial plateaus Patella Sagittal, frontal plane |
Incorporated into IKDC rating system |
IKDC , International Knee Documentations Committee.
Commonly Used Articular Cartilage Rating Systems
Outerbridge
Critical Points
Commonly Used Articular Cartilage Rating Systems
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