Healing of critical bone defects is evaluated based on Hounsfield unit (HU) values

Objective: To evaluate the clinical process of bone grafting in the second stage of induced membrane bone union in patients with tibial bone defects to infer the possibility of non-union and provide evidence for early clinical intervention, and establish a reliable and effective evaluation method combined with computed tomography (CT) to judge the fracture healing in patients with tibial bone loss treated with Masquelet's technique. Methods Patients with tibial bone defects who underwent Masquelet technique at our hospital between February 2017 and February 2020 were retrospectively analyzed. Hounsfield unit (HU) values of the patients were evaluated at different times during the second stage of bone grafting. Bone healing at the boundary value of 120HU output threshold (-1024HU-3071HU) was directionally selected, and the changes in growth volume of union (bone graft volume (selected according to HU value)/bone defect volume) were compared to analyze individual class bone union. Results A total of 42 patients with a segmental bone defect with a mean age of 40.5 years (40.5 ± 8.3 years) were included. The relationship between bone graft volume and time was analyzed by single factor repeated variable analysis (P = 0.016). Further curve regression analysis showed that the change in bone graft volume over time presented a logarithmic curve pattern (Y = 0.563 + 0.086*ln(X), Ra 2  = 0.608, P = 0.041). Conclusion The proposed imaging of Hounsfield unit (HU) can be used as a reference for the clinical judgment of bone grafting union.