Table I.

Frequency and grading of histopathologic features observed in the PCL tibial enthesis organ in nine non-arthritic cadaveric specimens. Features were graded on a scale of 0–3 where 0 represents an absence of the feature and 3 represents a severe instance of the feature

Histopathologic feature	Overall frequency	Grade 0	Grade 1	Grade 2	Grade 3
Enthesis changes
Intraligamentous calcification	22%	78%	11%	11%	0%
Matrix fissuring	56%	44%	33%	11%	11%
Cartilage cell clustering	44%	56%	11%	33%	0%
Cell hypertrophy	33%	67%	11%	22%	0%
Hypercellularity	11%	89%	11%	0%	0%
Hypocellularity	11%	89%	0%	11%	0%
Fibrillation of cartilage	11%	89%	11%	0%	0%
Delamination of cartilage	33%	67%	22%	0%	11%
Necrosis	22%	78%	11%	11%	0%
Cyst formation	22%	78%	22%	0%	0%
Neovascularisation	44%	56%	33%	0%	11%
Ligament changes (including accessory cartilages)
Intraligamentous calcification	22%	78%	22%	0%	0%
Matrix fissuring	67%	33%	11%	22%	33%
Cartilage cell clustering	33%	67%	11%	11%	11%
Cell hypertrophy	22%	78%	22%	0%	0%
Hypercellularity	22%	78%	11%	0%	11%
Hypocellularity	11%	89%	0%	0%	11%
Fibrillation of cartilage	11%	89%	11%	0%	0%
Delamination of cartilage	0%	100%	0%	0%	0%
Necrosis	22%	78%	11%	0%	33%
Cyst formation	33%	67%	22%	11%	0%
Neovascularisation	22%	78%	11%	0%	11%
Synovium changes
Inflammatory cell infiltration	11%	89%	11%	0%	0%
Cell hyperplasia	11%	89%	11%	0%	0%
Synovial villi	22%	78%	22%	0%	0%
Synovial invasion of the enthesis	11%	78%	11%	0%	0%
Other
PCL vascular intrusion at cortical bone	33%	67%	11%	11%	11%
Tide mark duplication	44%	56%	22%	11%	11%
Bone remodelling	44%	56%	22%	11%	11%
Cartilage formation within bone	33%	67%	22%	0%	11%
Enthesis tear	11%	89%	0%	11%	0%
Ligament tear	11%	89%	11%	0%	0%