Evaluation of Sternal Bone Healing with Computed Tomography and a Quantitative Scoring Algorithm

Objective: The exquisite bone detail offered by computed tomography makes it the ideal modality for evaluation of bone healing. However, few studies have investigated the normal computed tomographic appearance of the sternum after median sternotomy and, to the best of our knowledge, no computed tomographic classification of sternal healing has been proposed. Given the potential benefit of objective criteria, we propose a validated scoring classification of sternal healing using computed tomography for both clinical and investigational purposes. Methods: Computed tomography scans from 20 patients who underwent a median sternotomy were evaluated for sternal healing at either 3 or 6 months postoperatively. Five anatomic locations along the sternum were selected using defined criteria, and a 6-point quantitative scale was developed to evaluate sternal healing. Independent radiologists read and scored each of the 5 locations on the sternum. Inter- and intra-observer variability was assessed by calculating the kappa statistics to measure the reliability of the scoring algorithm. Results: Calculation of the kappa statistics indicated substantial agreement for intra-observer variability and substantial to almost perfect agreement for inter-observer variability. For intra-observer variability, the kappa statistics ranged from 0.591 to 0.802, and for inter-observer variability, the kappa statistics ranged from 0.590 to 0.969. When the two radiologists differed, the magnitude of the difference was no more than 1 or 2 points. Conclusion: This simple system of evaluating sternal healing had high inter- and intra-observer reliability. Therefore, it may be considered a valid method for assessing sternal osteosynthesis for both clinical and investigative purposes. Ultramini abstract: (49 words): Few studies have investigated the normal computed tomography appearance of the sternum after median sternotomy, and we knew of no computed tomography-based classification of sternal healing. Given the potential benefit of objective criteria, we designed and validated a scoring classification of sternal osteosynthesis for both clinical and investigational purposes.