Background

 

ICRS Grade 3 Chondral LesionCartilage imageOC defect

 

Anatomy / Biochemistry

 

Constituents of cartilage

 

Extracellular matrix (proteogylcans + collagen + water) + chondrocytes

 

Type II Collagen Proteoglycans Water Chondrocytes

Triple helix

 

Glucosaminoglycans (GAG)

Keratan sulphate

Chondroitin sulphate

Attracted to GAG Live in low oxygen, avascular environment

Tensile strength

Mechanical integrity

Negative charge has high affinity for water Resistant to compressive loads Make collagen and GAG

 

Structure of cartilage

 

CartilageCartilage

Superficial zone Middle / transitional Deep zone Calcified Zone / tidemark

Thin layer

10 - 20% thickness

40 - 60% 30% Secures cartilage to bone
Collagen fibers tightly packed and arranged in parallel

Proteoglycans

Thick collagen fibrils

Highest proteoglycan content

Largest collagen fibrils

Collagen arranged perpendicular

Anchors collagen to subchondral bone
High number of chondrocytes Much fewer chondrocytes Chondrocytes arranged in columns  

Protective layer

Provides tensile resistance

Resistance to compressive forces Greatest resistance to compressive forces  

 

Pathology

 

Inability to heal due to avascular nature and no pluripotent cells

 

Types

 

Chondral defects - trauma

Osteochondral defects - OCD, patella dislocations

 

ICRS Grade 4 Chondral LesionCartilage image

Chondral defect

 

Knee OCD Arthroscopy Type 4OC defect

Osteochondral defect

 

MRI

 

Chondral Defect Full ThicknessChondral defectMFC chondral

Chondral defect

 

MFC chondralChondral defect

 

Osteochondral defectOsteochondral defectOsteochondral defect

Osteochondral defect

 

OC defectOC defect

Osteochondral defect

 

CT

 

OC defectOC defect

 

CT osteochondral defect

 

Outerbridge Arthroscopy Classification

 

Grade 1:  Softening and swelling of the cartilage

Grade 2:  Partial thickness defect < 1.5 cm in diameter

Grade 3:  Fissuring to subchondral bone, > 1.5 cm in diameter

Grade 4:  Exposed subchondral bone

 

Issue - focus on size of cartilage lesion rather than depth

 

ICRS / International Cartilage Research Society Arthroscopy Classification

 

ICRSICRSICRSICRS

Grade I:   Nearly normal -  soft indentation / superficial fissures and cracks

Grade II:   Abnormal - cartilage lesions < 50% of cartilage depth

Grade III:  Severely abnormal - cartilage lesions > 50% of cartilage depth

Grade IV:  Severely abnormal - cartilage lesion down to subchondral bone

 

Dwyer et al Arthroscopy 2017

- inter-observer reliability 0.7

- intra-observer reliability 0.8

- correlation between arthroscopy and histological grading of depth 0.9

 

Normal Hyaline Cartilage

Grade 0 / normal

 

Grade 1 Cartilage LesionGrade 1 Chondral Lesion Femur

Grade I: soft cartilage, superficial fissures

 

Grade 2 Chondral Lesion

Grade II: cartilage lesion < 50%

 

ICRS Grade 3 Chondral LesionCartilage imageGrade 3 Chondral Injury

Grade III: cartilage lesion > 50%

 

ICRS Grade 4 Chondral LesionGrade IV cartilage

Grade IV: cartilage lesion down to subchondral bone

 

Sizing

 

3 or 5mm graduated probe

- measure in 2 dimensions

- give a size in cm2

- assumes that lesions are basically rectangular

- tend to overestimate size arthroscopically

 

Cartilage sizingFailed OCDChondral defect sizing