A Novel Method to Assess Healing of Segmental Bone Defects using the Induced Membrane Technique

Objective: Clinical concerns exist regarding the quality of bony consolidation in the context of the induced membrane technique. This study evaluates 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 establish a reliable and effective evaluation method combined with computed tomography (CT) to assess fracture healing. Methods: Patients with tibial bone defects who underwent the induced membrane technique at our hospital between February 2017 and February 2020 were retrospectively analyzed. The 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 the 120 HU output threshold (-1024 HU-3071 HU) was directionally selected, and the changes in the growth volume of union (new bone volume [selected according to HU value]/bone defect volume) were compared with analyzing individual class bone union. Method 1 involved X-rays revealing that at least three of the four cortices were continuous and at least 2 mm thick, with the patient being pain free. For Method 2, new bone volume (selected according to HU value/bone defect volume) at the stage was compared with analyzing individual class healing. Receiver operating characteristic curve analysis was used for Methods 1 and 2. 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 variation was analyzed by single factor repeated variable analysis (F = 6.477, 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 x ln(X), Ra2 = 0.608, p = 0.041). ROC curve analysis showed that Method 2 is superior to Method 1 (AUC: 86.3% vs. 68.3%, p < 0.05). Conclusion: The induced membrane technique could be used to treat traumatic long bone defects, with fewer complications and a higher healing rate. The proposed imaging grading of HU (new bone volume/bone defect volume) can be used as a reference for the quality of bony consolidation with the induced membrane technique.