This is an experimental study on human cadaver spines. The objective of this study is to compare the pullout forces between three screw augmentation methods and two different screw designs. Surgical interventions of patients with osteoporosis increase following the epidemiological development. Biomechanically the pedicle provides the strongest screw fixation in healthy bone, whereas in osteoporosis all areas of the vertebra are affected by the disease. This explains the high screw failure rates in those patients. Therefore PMMA augmentation of screws is often mandatory. This study involved investigation of the pullout forces of augmented transpedicular screws in five human lumbar spines (L1-L4). Each spine was treated with four different methods: non-augmented unperforated (solid) screw, perforated screw with vertebroplasty augmentation, solid screw with vertebroplasty augmentation and solid screw with balloon kyphoplasty augmentation. Screws were augmented with Polymethylmethacrylate (PMMA). The pullout forces were measured for each treatment with an Instron testing device. The bone mineral density was measured for each vertebra with Micro-CT. The statistical analysis was performed with a two-sided independent student t test. Forty screws (10 per group and level) were inserted. The vertebroplasty-augmented screws showed a significant higher pullout force (mean 918.5 N, P = 0.001) than control (mean 51 N), the balloon kyphoplasty group did not improve the pullout force significantly (mean 781 N, P > 0.05). However, leakage occurred in some cases treated with perforated screws. All spines showed osteoporosis on Micro-CT. Vertebroplasty-augmented screws, augmentation of perforated screws and balloon kyphoplasty augmented screws show higher pullout resistance than non-augmented screws. Significant higher pullout forces were only reached in the vertebroplasty augmented vertebra. The perforated screw design led to epidural leakage due to the position of the perforation in the screw. The position of the most proximal perforation is critical, depending on screw design and proper insertion depth. Nevertheless, using a properly designed perforated screw will facilitate augmentation and instrumentation in osteoporotic spines.

Cervical lordosis and kyphosis less than +7.5° resulted in no meaningful increase in IMP. Minor cervical kyphosis measuring +7.5° to +21° resulted in 2 to 5 mm Hg increases in IMP. As the cervical kyphotic deformity exceeded +21°, IMP increased significantly. ΔIMP with spinal alignment may help to explain the wide range of "normal" cervical neutral upright sagittal alignment in studies of asymptomatic individuals and may help further define cervical kyphotic deformity.

The Spine Tango registry is now accessible via the SSE webpage under www.eurospine.org-Spine Tango. Links to the Swiss/International, German and Austrian modules are provided as well as information about the philosophy, methodology and content. Following the links, the users are taken to the respective national modules for registration or log-in and data entry. The Swiss/International module, also accessible under www.spinetango.com, is used by all Swiss and international users, who do not have a separate national module. The physician administered forms for surgery, staged surgery and follow-up can be downloaded as PDFs.The officially recommended Spine Tango patient forms are also available. All forms were implemented in an online version and as scannable optical mark reader forms which can be ordered from the corresponding author.

Purpose. To compare efficacy of balloon kyphoplasty in restoring vertebral height and correcting kyphosis in patients having vertebra plana with or without osteonecrosis. Methods. 12 women and 3 men (mean age, 76 years), who had a complete vertebra plana with or without osteonecrosis (n=8 vs n=7), underwent balloon kyphoplasty. No external manoeuvres were performed before or during balloon kyphoplasty, except for positioning the patients in a prone posture on the operating table. The anterior, middle, and posterior vertebral height and the kyphotic angle were measured pre-and post-operatively with a digital imaging system. The vertebral height was measured as a percentage of the adjacent normal vertebral height. Results. Respectively in vertebra plana patients with or without osteonecrosis, the mean corrections of (1) kyphosis were 10º and 4º (p=0.099), (2) anterior vertebral height were 33% and 5% (p<0.001), (3) middle vertebral height were 38% and 18% (p=0.004), and (4) posterior vertebral height were 19% and 2% (p=0.031).

This article was mistakenly published under the category ''Review Article''. The correct category is ''Original Article''.