Table 1.

Microscopic grading system for synovial membrane histology

Outcome Parameter	Score	Description
Cellular infiltration	0	No mononuclear cells in the section
	1	Occasional small areas of mononuclear cells throughout the section
	2	Mild presence of mononuclear cells in 25% of the section
	3	Moderate presence of mononuclear cells in 25–50% of the section
	4	Marked presence of mononuclear cells in greater than 50% of the section
Vascularity	0	Normal
	1	Slight increase in vessels in focal locations throughout the section
	2	Mild increase in number and dilatation of vessels in focal locations throughout the section
	3	Moderate increase in number and dilatation of vessels up to 50% of the section
	4	Marked increase in number and dilatation of vessels in greater than 50% of the section
Intimal hyperplasia	0	None
	1	Villi with 2–4 rows of intimal cells within the section
	2	Villi with 4–5 rows of intimal cells over 25–50% of the section
	3	Villi with 4–5 rows of intimal cells over 50% of the section
	4	Villi with 5 or greater rows of intimal cells over 50% of the section
Subintimal edema	0	No edema
	1	Slight edema detected within section
	2	Mild edema within 25% of the section
	3	Moderate edema within 25–50% of the section
	4	Marked edema in greater than 50% of the section
Subintimal fibrosis	0	Normal
	1	Slight increase in fibrosis within the section
	2	Mild increase in fibrosis in 25% of the section
	3	Moderate increase in fibrosis in 25–50% of the section
	4	Marked increase in fibrosis in greater than 50% of the section

Microscopic grading system for synovial membrane histology in the carpal osteochondral fragment model.²⁰