In this study, researchers evaluated histological and immunocytochemical parameters that could be used to assess healing potential after scaphoid fractures and to correlate these findings with time intervals after fracture for the three parts of the scaphoid. The scaphoid is the most frequently fractured carpal bone and prone to non-union due to mechanical and biological factors.

Whereas the importance of stability is well documented, the evaluation of biological activity is mostly limited to the assessment of vascularity. Samples were taken during operative intervention in 33 patients with delayed or non-union of the scaphoid. The scaphoid bone plays a critical role in carpal kinematics due to its complex three-dimensional structure and function as a bridging link between the two carpal rows.

Even a small fracture gap of 1 mm and angular deformities can negatively influence fracture healing. A total of 80% of the scaphoid is covered by cartilage, resulting in tenuous blood supply further increasing the risk of non-union formation. For histological analysis, we used the most central parts of the samples, thereby reducing the amount of damaged tissue.

They carried out HE, Azan, Toluidine and Tartrate-resistant acid phosphatase (TRAP) staining to gain more histological information. Furthermore, they performed immunocytochemical characterisation of the cartilage composition by monitoring collagen 1 and 2 distribution and defined distinct parameters for the healing status dependent on the location of fracture.

In three cases with partial wrist fusion, the whole scaphoid was resected and, in addition to the above-mentioned histological analysis, the ultrastructure of the entire scaphoid bone was visualised by SEM and von Kossa staining. These samples of long-standing non-unions served as a reference for clinically non-active tissue.

Many different surgical procedures have been proposed to achieve reconstruction and bone healing in SNU. They showed that vascularised grafts have a better functional and fusion outcome compared with non-vascularised grafts. For the clinician, it is important to apply the least invasive method that is still able to achieve bone healing.

As the surgical procedures for treatment are manifold, the surgeon needs, in addition to refined radiological imaging, as much biological information on healing capacity as possible to make an informed decision. Results indicate that the time-dependent decrease in healing capacity originates from the distal pole and gap region.

Whereas biological activity at the proximal pole does not change significantly over time and is low even at the early stages. One limitation of our study is the low number of patients. However, the study still provides a thorough histological characterisation of scaphoid non-unions over a long-time range based on biological observations.

They could establish a set of valuable parameters to describe the healing capacity of SNU. The results of this study may provide a histological basis for further clinical studies with an impact on patient treatment.