Modified Bonar Score for Histologic Changes in Tendons

Description

The Bonar score is used to describe degenerative change within a tendon. The original Bonar score had categories for cell morphology, ground substance, collagen and vascularity. This was later expanded.

Exam: longitudinal section of the tendon, with H&E, mucin and collagen stains. The exam is coducted under light and polarized light sources.

Parameters:

(1) cell morphology (four fields at 200x)

(2) collagen arrangement under polarized light (one field at 100x)

(3) cellularity (one field at 100x)

(4) vascularity (10 fields of view at 400x)

(5) ground substance on mucin and collagen stains (one field at 100x)

(6) calcifications

(7) intratendinous adipocytes

Parameter	Finding	Points
cell morphology	elongated spindle-shaped nuclei; no obvious cytoplasm	0
	nucleus ovoid to round; cytoplasm not conspicuous	1
	nucleus round and slightly enlarged; small amount of cytoplasm	2
	large, round nucleus; abundant cytoplasm showing chondroid change	3
collagen arrangement	collagen in cohesive bundles; homogeneous	0
	some separation of fibers; overall bundle architecture preserved	1
	more separation of fibers; loss of demarcation; loss of normal polarization	2
	marked separation of fibers with complete loss of architecture	3
cellularity	mostly discrete cells	0
	areas of hypercellularity (> 30 nuclei per field)	1
	areas of hypercellularity and hypocellularity	2
	mostly acellular	3
vascularity	inconspicuous	0
	occasional clusters (1 in 10 hpf)	1
	2-3 clusters in 10 hpf	2
	multiple clusters and/or completely avasuclar	3
ground substance	none stainable	0
	mucin between discrete bundles	1
	mucin within bundles; bundles not clearly demarcated	2
	abundant mucin wtih inconspicuous collagen	3
calcifications	absent	0
	present	1
intratendinous adipocytes	absent	0
	present	2.5

Interpretation:

• minimum score: 0

• maximum score: 20

• The higher the score the greater the degenerative change.

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