Table 3.

The classification systems of FAIS-related cartilage lesions^a

Classification	Grade	Definition	Base	Target area
Outerbridge	1	Softening and swelling of the cartilage	Gross appearance of cartilage lesions (extent)	Acetabulum and femoral head
	2	Fragmentation and fissuring in an area half an inch or less in diameter
	3	Fragmentation and fissuring in an area more than half an inch in diameter.
	4	Erosion of cartilage down to bone
Beck	0	Normal-Cartilage macroscopically intact	Pathological process in disease progression Surgical dislocation findings	Acetabulum: Chondrolabral junction (transition zone)
	1	Malacia-Fibrillation or roughening of surface
	2	Pitting malacia-Roughening, partially thinning and full-thickness defects or deep fissuring to the bone
	3	Debonding-Loss of fixation to the subchondral bone, macroscopically sound cartilage; carpet phenomenon
	4	Cleavage-Loss of fixation to the Subchondral bone; frayed edges, thinning of the cartilage
	5	Defect-Full thickness defect
ALAD	0	Cartilage macroscopically intact	Pathological process in disease progression Hip arthroscopy findings	Acetabulum: Chondrolabral junction (transition zone)
	1	Softening of the adjacent cartilage
	2	Early peel of the cartilage
	3	Large flap of the cartilage
	4	Loss of cartilage
Konan/Haddad	0	Normal cartilage	Pathological process in disease progression Hip arthroscopy findings	Acetabulum: Chondrolabral junction (transition zone)
	1	Wave sign
	2	Cleavage tear
	3	Delamination
	4	Exposed bone
		Using combined with six acetabular zones method
		Grades 1, 3 and 4 could be further grouped as A, B and C based on whether the lesion was less than one-third of the distance from the acetabular rim to the cotyloid fossa (A), one-third to two-thirds of this distance (B) or greater than two-thirds of this distance (C).
ICRS	0	Normal	Gross appearance of cartilage lesions (depth)	Acetabulum and femoral head
	1	Nearly normal-Superficial lesions. Soft indentation (A) and/or superficial fissures and cracks (B)
	2	Abnormal-Lesions extending down to < 50% of cartilage depth.
	3	Severely Abnormal-Cartilage defects extending down > 50% of cartilage depth (A) as well as down to calcified layer (B) and down to but not through the subchondral bone (C). Blisters are included in this Grade (D).
	4	Severely Abnormal-Lesions through the subchondral bone
Bern	1	Normal	Clinical experience Cover the entire spectrum of early hip cartilage lesions independent of etiology	Acetabulum: Chondrolabral junction (transition zone)
	2	Discoloration and fibrillation-Macroscopically reddish or yellowish discoloration of the cartilage
	3	Softening and thinning-Provocation of a cartilage indentation with the probe in a zone with softening of cartilage
	4	Wave sign-Loss of fixation to the subchondral bone without flap formation, carpet phenomenon on palpation by a probe
	5	Cleavage tear-Frayed edges in the cartilage, typically near the chondrolabral junction with preserved attachment to the subchondral bone
	6	Delamination-Delamination of the cartilage, cartilage flap; loss of fixation to the subchondral bone
	7	Exposed bone-Loosening of cartilage with exposed bone, bony palpation with probe
Sampson	AC0	No damage	Treatment strategies Pathological process in disease progression	Acetabulum: Chondrolabral junction (transition zone) Femoral head
	AC1	Softening no wave sign
	AC1w	Softening with wave sign intact labrocartilage junction
	AC1wTj	Softening with wave sign and torn labrocartilage junction
	AC1wD	Softening with wave sign and intact labrocartilage junction with delamination
	AC1wTjD	Softening with wave sign and torn labrocartilage junction with delamination
	AC2	Fibrillation
	AC2Tj	Fibrillation with torn labrocartilage junction
	AC3	Exposed bone small area < 1 cm2
	AC4	Exposed bone large area > 1 cm2
		Abbreviations: A, acetabulum; C, cartilage defects; D, with delamination; Tj, Torn labrocartilage junction; w, with wave sign.
	HC 0	No damage
	HC 0T	Uniform thinning (T)
	HC 1	Softening
	HC 2	Fibrillation
	HC 3	Exposed bone
	HC 4	Any delamination
	HTD	traumatic defect (size in mm)
	HDZ	demarcation zone from FAI
		Abbreviations: HC, femoral head cartilage; T, thinning; TD, traumatic defect; DZ, demarcation zone from FAI.
MAHORN	0	Normal-Macroscopically sound cartilage	Pathological process in disease progression Hip arthroscopy findings	Acetabulum: Chondrolabral junction (transition zone)
	1	Focal defect or extensive softening
	2	Bubble-Detached cartilage from bone with intact periphery
	3	Pocket-Detached cartilage from bone with one free edge
	4	Flap-Detached cartilage from bone with more than one free edge
	5	Exposed bone

^aMAHORN, Multicenter Arthroscopy of the Hip Outcomes Research Network