Evaluation of bone remodeling in regard to the age of scaphoid non-unions

Abstract

Aim: To analyse bone remodeling in regard to the age of scaphoid non-unions (SNU) with immunohistochemistry.

Methods: Thirty-six patients with symptomatic SNU underwent surgery with resection of the pseudarthrosis. The resected material was evaluated histologically after staining with hematoxylin-eosin (HE), tartrate resistant acid phosphatase (TRAP), CD 68, osteocalcin (OC) and osteopontin (OP). Histological examination was performed in a blinded fashion.

Results: The number of multinuclear osteoclasts in the TRAP-staining correlated with the age of the SNU and was significantly higher in younger SNU (P = 0.034; r = 0.75). A higher number of OP-immunoreactive osteoblasts significantly correlated with a higher number of OC-immunoreactive osteoblasts (P = 0.001; r = 0.55). Furthermore, a greater number of OP-immunoreactive osteoblasts correlated significantly with a higher number of OP-immunoreactive multinuclear osteoclasts (P = 0.008; r = 0.43). SNU older than 6 mo showed a significant decrease of the number of fibroblasts (P = 0.04). Smoking and the age of the patients had no influence on bone remodeling in SNU.

Conclusion: Multinuclear osteoclasts showed a significant decrease in relation to the age of SNU. However, most of the immunhistochemical findings of bone remodeling do not correlate with the age of the SNU. This indicates a permanent imbalance of bone formation and resorption as indicated by a concurrent increase in both osteoblast and osteoclast numbers. A clear histological differentiation into phases of bone remodeling in SNU is not possible.

Keywords: Bone remodeling; Histology; Immunohistological staining; Scaphoid; Scaphoid non-union; Wrist joint.

Figure 1

Morphological analysis. A 7-mo-old SNU is shown (A-C). A: HE-staining shows osteoblasts (black arrow) and osteocytes (white arrow) in the underlying sclerosed bone; B: OC-staining shows osteocytes (arrow) in detail; C: OP-staining shows the osteoblasts (arrow) lining a Haversian vessel in detail. Original magnification 200 × (A, B), 400 × (C). SNU: Scaphoid non-unions; OP: Osteopontin; OC: Osteocalcin.

Figure 2

Osteoclasts. Examples for multinuclear osteoclasts as seen in the HE-staining (A and B), the TRAP (C), CD 68 (D) and OP (E) staining. (A-D) show osteoclasts (arrows) in a 10-mo-old SNU, whereas (E) shows an osteoclast in a 7-mo-old SNU. Original magnification 100 × (A), 200 × (C), 400 × (B, D, E). SNU: Scaphoid non-unions; OP: Osteopontin; TRAP: Tartrate resistant acid phosphatase.

Figure 3

Non-union tissue in the hematoxylin-eosin staining. A: Non-union tissue with fibrocartilage covered by a layer of synovium-like lining cells (arrow) of a 60-mo-old SNU; B: Fibrous tissue rich in fibroblasts of a 10-mo-old SNU. Note the contrast in cell number as compared to the 60-mo-old SNU in A; C: Fibrous tissue with few fibroblasts, same patient as in A. Original magnification 100 × (A), 200 × (B, C). SNU: Scaphoid non-unions.

Figure 4

Multinuclear osteoclasts in correlation to the age of the scaphoid non-unions. The number of multinuclear osteoclasts in the TRAP-staining was significantly higher in younger SNU (P = 0.034; r = 0.75). SNU: Scaphoid non-unions; TRAP: Tartrate resistant acid phosphatase.

Figure 5

Correlation between osteoblasts in the osteopontin- and osteocalcin- immunohistochemistry. A greater number of OC-immunoreactive osteoblasts correlated significantly with a greater number of OP-immunoreactive osteoblasts (P = 0.001; r = 0.55). OC: Osteocalcin; OP: Osteopontin.

Figure 6

Correlation between osteopontin-immunoreactive osteoblasts and multinuclear osteoclasts. A greater number of OP-immunoreactive osteoblasts correlated significantly with a greater number of OP-immunoreactive multinuclear osteoclasts (P = 0.008; r = 0.43). OP: Osteopontin.