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Several 3D reconstruction techniques deriving from stereoradiographic DLT have been presented during the last 15 years, but these techniques have usually been limited in accuracy because of the small number of corresponding anatomical landmarks identified on both radiographs. A new technique has recently been proposed to perform 3D reconstruction of the spine using not only the stereo-corresponding anatomical landmarks (seen on both frontal and sagittal X-ray films) but also some non-stereo-corresponding ones. This technique (called non-stereo-corresponding points or NSCP) has already been used for cervical dry vertebrae. In the present study, we focus on the validation of this technique for lumbar vertebrae by comparing four techniques: direct measurement, CT scan, 3D reconstruction by stereoradiography using a direct linear transformation (DLT) algorithm and the NSCP technique. The accuracy of the NSCP technique was also evaluated on different vertebral regions. The global results show mean errors of 1.1 mm and maximum of 7.8 mm with regard to direct measurements. These mean errors are close to those obtained using 3D reconstructions from CT scan using 1 mm cuts.

This is a retrospective study on a series of 70 patients with thoracolumbar fractures (TL), surgically treated by the in situ bending technique (ISB). Its purpose is to show the performances and limits of the ISB technique for the early correction of post-traumatic spine deformities as well as to estimate the overall outcome in this series and to discuss the indications for anterior grafting. Although the management of limbs fractures is a cleared issue today, spine fractures management is still a matter of debate. Surgical treatment progresses fast, while indications, the fixation techniques, fracture reduction options, and associated grafting are still blurry. Seventy patients with TL fractures, mean age 40.3 years (20-80) were treated by posterior fusion with a standard construct and deformity reduction by means of the ISB technique. Mean follow-up was 30.7 months (12-78). Pre- and post-operative deformity was evaluated and the relative deformity as defined by Farcy's sagittal index (SIF) was analyzed. Thirty-eight patients underwent anterior interbody grafting. The pre-operative SIF decreased from 16.98 to 1.62 degrees (15.36 degrees decrease). Eighty percent of patients were normo- or hyper-corrected. The loss of correction during the follow-up occurred within the disc (SIF: -2.24 degrees , vertebral kyphosis 0.94 degrees , p<0.001), and was lower in patients who underwent secondary anterior grafting (-5.21 degrees vs.-1.18 degrees , p=0.002). Clinical outcome is good (Oswestry=29.75) and seems to be better in cases of double approach (20.71 vs. 37.,4, p=0.001). Sepsis occurred in ten cases, and two patients experienced construct dismounting. One patient had a retroperitoneal hematoma that required embolization. Seventy-one percent of operated patients went back to their previous work after surgery. Spine fractures deserve an efficient treatment. The ISB technique improves post traumatic kyphosis. This results is maintained at long term if the posterior fusion is associated with anterior grafting in cases where the correction within the disc exceeds 50% of the total correction.

These data may be used as 3-D referential values of spinal and pelvic alignment.

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