Table 2.

Histological grading scale for the degree of healing

Quality of union	No sign of fibrous or other union	0
	Fibrous union 1	1
	Fibrocartilaginous union or cartilage union 2	2
	Mineralizing cartilage and bone union 3	3
	Bone union	4
Cortex development and remodeling	No cortex formed	0
	Formation of new bone along exterior borders	1
	Recognizable formation of both the outer cortex border and the medullary space	2
	Cortices formed but incomplete bridging	3
	Complete formation of cortices with bridging of defect	4
Bone-graft incorporation and new-bone formation
No new bone, all or most of graft visible	Graft material present, no incorporation, and no new-bone formation	0
	Graft present, some incorporation with new-bone formation, and small amount of new bone	1
	Graft present, some incorporation with new-bone formation, and moderate amount of new bone	2
Decreasing graft, increasing new bone	Graft present, some incorporation with new-bone formation continuous with host bone, and early remodelling changes in new bone	3
	Decreased amount of graft (compared with grade 3), good graft incorporation, and ample new bone	4
	Less amount of graft still visible (compared with grade 4), good incorporation of graft and new bone with host and ample new bone	5
No graft visible, extensive new bone	Difficult to differentiate graft from new bone, excellent incorporation, and advanced remodelling of new bone with graft and host	6