Vertebroplasty and kyphoplasty seem to be equivalent methods in strengthening osteoporotic vertebrae. However, these results cannot be transferred to the treatment of fractures with these methods. A "physiologic" loading situation was achieved by complex motion, including all combinations of flexion/extension with lateral bending during eccentric cyclic loading.

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Object. Percutaneous vertebro- and kyphoplasty have become established methods for the treatment of uncomplicated osteoporotic vertebral fractures. In the setting of severe fractures involving fragmentation of the posterior wall and neural compromise, however, decompressive surgery cannot be performed and epidural cement leakage is poorly controlled. A microsurgical interlaminary approach for vertebro- and kyphoplasty was developed to allow spinal decompression and control of the spinal canal during augmentation. Methods. Interlaminary vertebro- or kyphoplasty was performed in 24 patients with osteoporotic fractures involving neural compression or posterior wall fragmentation. After unilateral microsurgical fenestration, decompression of the spine, and gentle mobilization of the thecal sac, vertebro- or kyphoplasty was performed directly through the posterior wall of the fractured vertebral body. Cement was injected under microscopic and fluoroscopic control, with the option of immediate exploration of the exposed spinal canal. Thirty-four levels (T-8 to L-5) were treated. Mean blood loss was less than 100 ml and augmentation added 10 to 40 minutes to the entire procedure. Cement leakage associated with the kyphoplasty procedure was less than that in vertebroplasty. There were no major complications. One patient was lost to follow up. Clinical outcome was good or excellent in 17 of the 23 patients available for follow-up (1 to 31—month) evaluation. Conclusions. The present microsurgical interlaminary approach for vertebro- and kyphoplasty enables treatment of severe osteoporotic fractures involving fragmentation of the posterior wall and neural compromise. Decompressive surgery is possible and the risk of epidural cement leakage is controlled intraoperatively. This technique can be regarded as a procedure on the treatment continuum between percutaneous augmentation and conventional open reconstruction.

While Kyphoplasty is increasingly becoming a recognised minimally invasive treatment option for osteoporotic vertebral fractures and neoplastic vertebral collapse, the experience in the treatment of vertebrae of the mid (T5-8)- and high (T1-4) thoracic levels is limited. The slender pedicle morphology restricts the transpedicular approach at these levels, necessitating extrapedicular placement techniques. Fifty five vertebrae of 32 consecutive patients were treated with kyphoplasty at levels ranging from T2-T8 for vertebral fractures (27 patients) or osteolytic collapse (5 patients). All procedures were performed through the transcostovertebral approach under fluoroscopic guidance. The radioanatomical landmarks of this minimally invasive approach were consistently identified and strictly adhered to. One fracture required open instrumentation due to posterior column injury in addition to kyphoplasty. Identification of specific radioanatomical landmarks allowed precise tool introduction in all cases without intraspinal or paravertebral malplacement. Average operating time for patients with osteoporotic fractures was 30 min per level (range 13-60 min) and 52 min per level (range 35-95 min) in neoplastic cases. Biopsy yield in patients with known or suspected malignancies was 100%. Epidural cement leakage was detected in one patient with pedicular osteolysis. Perforation of the lateral vertebral cortex during balloon inflation occurred in another patient. Both intraoperative complications were without clinical significance. Kyphoplasty in mid- to -high thoracic levels is possible via the transcostovertebral route under fluoroscopic guidance. Strict adherence to a stepwise protocol of tool introduction following defined radioanatomical landmarks is mandatory for the safe completion of this minimally invasive technique.

Spondylitis is a rare complication of vertebroplasty. In the presented case a satisfactory result could be achieved through conservative antibiotic therapy and restriction of movement.