The Agreement Between Radiographic and Surgical Measurements of Intervertebral Disc Height: A Cadaveric Study

Objective: Measurement of disc height has various clinical implications. Radiographic measurement of disc height may present inaccurate results and its direct “surgical” confirmation has not been studied. This study aimed to evaluate the agreement between the radio- graphic and post-discectomy surgical measurements of human intervertebral discs’ height C2-C3 thru L5-S1. Material and Methods: Eleven cadaver spines (243 discs) were studied. Before discectomies, the heights of all intervertebral discs were measured radiologically, using the method proposed by Frobin et al., which had been originally used for lumbar levels. Then, discec- tomies were performed and the discs were measured directly, using surgical disc spacers. Results: Mean values and standard deviations for radio- graphic and direct measurements of disc heights were, respectively, 4.7±0.6 mm and 4.5±0.6 mm for cervical, 5.1±0.7 mm and 4.9±0.7 mm for thoracic, and 11.3±2.5 mm and 10.9±1.8 mm for lumbar regions. The agree- ment between radiographic and direct measurements was good. Conclusion: The results from this study suggest that it is possible to estimate correctly the post-discectomy sur- gical heights of intervertebral discs for all spine regions by using non-magnified preoperative lateral X-rays and the method described by Frobin et al.