Introduction
Unfortunately,
articular cartilage has very limited repair abilities. Damage
can occur to the cartilage cap as a partial thickness or full
thickness defect. Partial thickness lesions (lesions that do
not reach the subchondral bone) do not heal spontaneously and
usually progress to degeneration of the articular surface. Full
thickness defects (defects that penetrate the subchondral bone)
undergo repair, though with a repair type cartilage called fibrocartilage.
Fibrocartilage does not exhibit the same type of biomechanical
properties as the smooth hylane cartilage. Our native ability
to repair either partial or full thickness articular defects
is not optimal. There have been many historical attempts to
provide a solution to this problem but none have proved successful.
Recent developments have led to encouraging short-term results,
including OATS.
Classification
and Diagnosis of Articular Damage
Diagnosis
of a cartilage defect can be very difficult. Clinical history
and examination, standard radiographs and MRI, are of moderate
diagnostic accuracy. In most situations, a careful arthroscopic
examination is the most helpful diagnostic tool. Classification
of articular cartilage defects has historically been noted during
arthroscopic procedures. Several historical grading systems
have been utilized including Noyes, Bauer/Jackson and Outerbridge.
Noyes analyzed the following to develop a score or grade: (1)
The description of the surface, (2) the depth (extent), (3)
the diameter and (4) the location. Bauer and Jackson classified
lesions according to damage patterns: (type I is linear, II
is stellate, III is a flap, IV is a crater, V is fibrillation,and
VI is degradation. Outerbridge, though originally developed
for chondromalacia patella, has been used for articular lesions
elsewhere. The scale was Grade 0 which is normal cartilage,
Grade I which is softening or swelling, Grade II which is fissuring
not reaching the subchondral bone and less than 0.5 cm in size,
Grade III which is fissuring to the subchondral bone less than
0.5 cm in size and Grade IV which is subchondral bone exposure.
Unfortunately, these grading systems are somewhat subjective
and qualitative which leads to difficulties in evaluation and
assessment. In 1997, the International Cartilage Repair Society
(IRCS) proposed that all chondral injuries should include an
assessment of the size, the depth, the precise location, and
a description of the opposing surface. In 1998, ICRS founded
the Articular Cartilage Imaging Group (http://www.cartilage.org)
to establish an acceptable imaging protocol to help evaluate
chondral imaging.
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| Introduction
Classification and Diagnosis of Articular Damage Diagnosis of a cartilage defect can be very difficult. Clinical history and examination, standard radiographs and MRI, are of moderate diagnostic accuracy. In most situations, a careful arthroscopic examination is the most helpful diagnostic tool. Classification of articular cartilage defects has historically been noted during arthroscopic procedures. Several historical grading systems have been utilized including Noyes, Bauer/Jackson and Outerbridge. Noyes analyzed the following to develop a score or grade: (1) The description of the surface, (2) the depth (extent), (3) the diameter and (4) the location. Bauer and Jackson classified lesions according to damage patterns: (type I is linear, II is stellate, III is a flap, IV is a crater, V is fibrillation,and VI is degradation. Outerbridge, though originally developed for chondromalacia patella, has been used for articular lesions elsewhere. The scale was Grade 0 which is normal cartilage, Grade I which is softening or swelling, Grade II which is fissuring not reaching the subchondral bone and less than 0.5 cm in size, Grade III which is fissuring to the subchondral bone less than 0.5 cm in size and Grade IV which is subchondral bone exposure. Unfortunately, these grading systems are somewhat subjective and qualitative which leads to difficulties in evaluation and assessment. In 1997, the International Cartilage Repair Society (IRCS) proposed that all chondral injuries should include an assessment of the size, the depth, the precise location, and a description of the opposing surface. In 1998, ICRS founded the Articular Cartilage Imaging Group (http://www.cartilage.org) to establish an acceptable imaging protocol to help evaluate chondral imaging.
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