TABLE 7.

Immunohistochemistry findings

Author	Classification	Immunohistochemistry
Cuthbert 8	Atrophic	Presence of SDF‐1, VEGF and BMP‐2 in NU tissue. CD 45 staining: greater in induced membrane than in non‐union. Non‐union tissue contains significantly greater percentage of cells expressing (i) pericyte (13.8% vs. 4.9%), (ii) CD31+ endothelial cells (18.2% vs. 5.5%) phenotypic markers. Non‐union tissue had significantly reduced numbers of lymphocytes (6.8% vs. 22.2%)
Burska 18	Not mentioned	PIGF was higher in non‐union patients, reaching significance at Days 1 and 3 (p < 0.05); but less marked at Day 5 (p = 0.09). PIGF displayed initial massive surge followed by rapid decline in non‐union patients. TGF‐beta 2 appeared higher in union group (not statistically significant). Levels of MCP‐1 and IL8 showed no clear difference between non‐union and union groups.
El‐Jawhari 19	Atrophic	IFN‐γ, TNF‐α and IL‐1 levels similar between non‐union, union and control arms. However, lower levels of IL‐17 detected at later stages of fracture healing (vs. union and control arms)
Schira 13	Atrophic	ALP reached higher levels in scaphoid non‐unions as opposed to cancellous bone. Likewise, immunofluorescence for phosphorylated SMAD2/3 revealed increased activity in scaphoid non‐unions.
Han 14	Not mentioned	The depth of BMP‐2 staining in the cytoplasm increased with increasing proximity to the new bone formation region, and there was some staining of the Golgi apparatus, showing that BMP‐2 was locally generated. A wide variety of cells, including epithelial cells, smooth muscle cells around the small blood vessels, fusiform fibroblast‐like cells and chondrocyte cells, showed positive staining in the fibrous tissues, indicating osteogenesis. There was no difference in the immunostaining of fibrous tissue between the samples with and without new bone. There was no positive BMP staining in the extracellular matrix or the fibrous tissue space. Sub‐parts of view, fracture fragments were mainly fibrotic tissues and BMP‐2 staining was negative. In the surrounding tissues, especially in the sticking scars and posted plate scars, neovascular and woven bone filled in a lot of the fibrous tissues, and in the vicinity, there were stained cells, indicating BMP‐2 expression. There was a small amount of cartilage with positive staining in the cytoplasm, without expression in fibrous tissues of the closed medullary cavity. DCN expression was extensive in the interstitial fracture fragments. There was no positive staining of cartilage cells in the medullary cavity. DCN expression in the sticking scars was close to perivascular. The rate of expression of BMP‐2 was highest in the posted bone scar group, and was low in the bone ends and canal content group (p < 0.05). There was no significant difference between the other two groups. The fracture fragment group had the highest DCN expression, with significant differences from the other two groups; the least significant difference analysis showed that between the fracture fragment group and the other two groups, p < 0.05; between the other two groups, p > 0.05
Wang 15	Atrophic/hypertrophic	The mean optical density of BMP‐2 was 0.154 ± 0.041 in hypertrophic non‐union tissue, 0.137 ± 0.037 in atrophic non‐union tissue, there was no significant difference between the 2 groups (p > 0.05). The mean optical density of BMP‐2 was 0.148 ± 0.040 in the 20‐ to 35‐year‐old group, 0.142 ± 0.040 in the 35‐ to 50‐year‐old group, 0.146 ± 0.056 in the more than 50‐year‐old group, there was no significant difference among the three groups (p > 0.05). The mean optical density of BMP‐2 was 0.145 ± 0.037 in the 9–12 months group, 0.147 ± 0.0400 in the 13–24 months group, 0.145 ± 0.054 in the more than 24 months group, there was no significant difference among the 3 groups (p > 0.05).
Schwabe 16	Atrophic	Bone morphogenic antagonists were demonstrated in non‐union and control tissue.