It is recommended to plan realignment for medial open wedge high tibial osteotomy at a maximum of 2° valgus. Cite this article: Bone Joint J 2016;98-B:628-33.

From October 1, 2007, to October 10, 2008, we performed 50 navigated high tibial osteotomies (medial opening wedge). The mean age of the patients was 46.58 years (range, 16-70). Twenty-three osteotomies were performed in women and 27 in men. Two patients received osteotomies on both sites. Average malalignment was 6.4 degrees varus (range, 3 degrees -10.8 degrees ). Sixteen osteotomies were performed on the right side and 34 on the left side. Detailed preoperative planning was performed using the digital MediCad (Hectec GmbH, Niederviehbach, Germany) program based on the malalignment test. Navigation data were compared using full weight-bearing and intraoperative radiographs. Navigation was shown to be an excellent device for intraoperative control of the amount of correction achieved and offers additional information regarding the lateral plain, ligaments, flexion and extension.

Primary bone tumors and tumor-like lesions of the vertebral column are rare in children. After operative tumor resection, 25 children under the age of 17 could be reviewed in a retrospective analysis. Malignant bone tumors occurred only twice in the region of the vertebral body. No deformity was registered in 9 of 16 cases after local tumor resection with and without laminectomy on one level. In contrast, after resection of one or both facets in combination with laminectomy cranial to L4 or thoracal, progressive kyphosis was found within 6-22 months postoperatively in four cases. This required a secondary fusion. After primary fusion and instrumentation, no deformity was registered. In nine cases with a location of the tumor in the vertebral body, only two patients developed a secondary instability of the spine. Both cases had no primary fusion. The other seven patients with initial fusion and instrumentation showed no deformity within 24 up to 127 months postoperatively. These results are compared with data from the current literature.