Table 1.

Bonar Score: updated and with clarification of terms and grades.

	Grade 0	Grade 1	Grade 2	Grade 3
Cell morphology  Four fields of view, 200×	Inconspicuous elongated spindle shaped nuclei with no obvious cytoplasm at light microscopy	Increased roundness: nucleus becomes more ovoid to round in shape without conspicuous cytoplasm	Increased roundness and size; the nucleus is round, slightly enlarged and a small amount of cytoplasm is visible	Nucleus is round, large with abundant cytoplasm and lacuna formation (chondroid change)
Collagen arrangement  Polarized  One field of view, 100×	Collagen arranged in tightly cohesive well demarcated bundles with a smooth dense bright homogenous polarization pattern with normal crimping	Diminished fibre polarization; separation of individual fibre bundles but with maintenance of overall bundle architecture Non homogeneous polarization	Bundle changes: separation and loss of demarcation of fibre bundles, giving rise to expansion of the tissue overall and clear loss of normal polarization pattern	Marked separation of fibre bundles with complete loss of architecture
Cellularity  One field of view, 100×	Mainly discrete cells	Hyper cellulara, in runs and/or increased cell numbers	Areas of hypoa as well as hypera cellularity	Area of assessment is mostly a-cellular
Vascularity  ≤ 10 fields of view, 400×	Inconspicuous blood vessels coursing between bundles	Occasional cluster of vessel, <2 per 10 high power fields	2–3 clusters of capillaries power 10 high power field	Areas with greater than 3 clusters per 10 high power fields, and/or areas of pathological a-vascularity
Ground substance  One field of view, 100×	Not stainable ground substance	Stainable mucin between bundles but bundles still discrete	Stainable mucin within bundles with loss of clear demarcation of bundles	Abundant mucin throughout the section with inconspicuous collagen staining

^aHypocellular: < 20 nuclei per field; hypercellular: >30 nuclei per field. Plus 2.5 points for each of: calcification; adipocytes (intratendinous). Total score: a tendon with the most pathology will score 20. A tendon with no observable pathology will score 0.