[Value of routine transpedicular biopsies in kyphoplasty and vertebroplasty for vertebral compression fractures : A survey among 250 spine surgeons]. / Stellenwert der transpedikulären Biopsie bei Kypho- und Vertebroplastien von Wirbelkörperfrakturen : Eine Umfrage unter 250 Wirbelsäulenchirurgen.

BACKGROUND: Transpedicular cement augmentation is an established therapeutic option in the treatment of pathologic compression fractures of the spine. In addition to osteoporosis, underlying metastatic diseases or, more rarely, a primary bone tumor are recurrent causes of vertebral compression fractures without adequate trauma. OBJECTIVE: To obtain a current opinion among spine surgeons in Germany, Switzerland, and Austria on the value of transpedicular biopsy during kyphoplasty and vertebroplasty of vertebral body fractures. MATERIAL AND METHODS: A web-based (UmfrageOnline®) questionnaire with 11 questions was created and sent to the email distribution lists of the German Spine Society (DWG), the Austrian Society for Spine Surgery (spine.at), and the Swiss Society for Spinal Surgery (SGS), as well as to the email distribution list of the Spine Section of the German Society for Orthopedics and Trauma Surgery (DGOU). RESULTS: Of a total of 2675 spine surgeons contacted 250 (9.3%) responded to the survey. Approximately one third (29.8%) of respondents regularly perform a transpedicular biopsy with each kyphoplasty or vertebroplasty. Reasons cited for biopsy were image morphology (79.7%) or history of suspected (66.0%) or present (71.4%) tumor disease. Reasons cited against routine biopsy were the associated costs and the limited informative value of the biopsies obtained. DISCUSSION: Nearly one third of the spine surgeons surveyed regularly perform a transpedicular biopsy with each kyphoplasty or vertebroplasty. Almost all respondents perform biopsies at least when there is an imaging morphologic suspicion of tumor disease or tumor disease is known or suspected based on risk factors. Future studies need to further clarify the cost-effectiveness of transpedicular biopsy.

[Hounsfield units as a measure of bone density-applications in spine surgery]. / "Hounsfield units" als Maß für die Knochendichte ­ Anwendungsmöglichkeiten in der Wirbelsäulenchirurgie.

Despite today's good diagnostic and therapeutic options for osteoporosis, the number of unidentified cases is very high and therapy is therefore usually inadequate. Frequently, the diagnosis of osteoporosis is made only after the occurrence of a fracture. The reason for this, apart from the costs incurred as well as the additional radiation exposure of the diagnostics, is certainly the limited availability of dual energy X­ray absorptiometry (DEXA) as well as quantitative computed tomography (q-CT). In search of an alternative technique, Hounsfield units (HU) of the clinical CT examination proved to be ground-breaking: the results of previous investigations demonstrated a reliable correlation between the T values of the DEXA measurement and the HU of the same vertebral body. Due to the widespread use of clinical CT scans of the thorax and the abdomen for a variety of indications, it is expected that the number of unidentified cases of osteoporosis can be significantly reduced-without additional costs and radiation exposure associated with osteoporosis screening. In addition to osteoporosis diagnostics, the calculated HU may also provide better preoperative planning as well as predicting the further course of the disease. Thus, the risk for vertebral body fractures, screw loosening and cage sintering after ventral fusion operations can be sufficiently predicted. In this way, preoperative modifications to the surgical procedure can be made to reduce the risk of implant failure.

Analysis of a Unilateral Bridging Cage for Lumbar Interbody Fusion: 2-Year Clinical Results and Fusion Rate with a Focus on Subsidence.

PURPOSE: The aim of this study was to evaluate the biomechanical stability and the clinical and radiographic outcomes in patients undergoing transforaminal lumbar interbody fusion (TLIF) using an oblique bridging cage with a particular focus on subsidence. METHODS: Finite element models were developed to compare the biomechanics of the oblique cage with conventional posterior lumbar interbody fusion and banana-shaped cages with TLIF. Additionally, a retrospective review of a prospective collected database was performed to investigate the clinical and radiologic results with a focus on the subsidence rate using an oblique polyetheretherketone (PEEK) cage with a bicortical load-bearing design. We included 87 patients with degenerative pathologic conditions of the lumbar spine who underwent TLIF. The clinical outcome was assessed using the Oswestry Low Back Pain Disability Questionnaire and the visual analogue scale. Fusion and subsidence rates were assessed radiographically. RESULTS: The finite element models showed no differences in stability on compression or extension/flexion. The oblique cage differed in terms of the location of the maximal stresses. A total of 105 levels were fused. The level at which fusion was most frequently performed was L4-L5 (59%). The fusion rate was 93.2% after 24 months. Subsidence was found at 4 levels after the last follow-up visit (3.9%). Overall clinical outcome improvement was achieved after 24 months. CONCLUSION: Regarding fusion, the use of an oblique PEEK cage with a cortical load-bearing design provided highly satisfactory clinical and radiologic results after 2 years. A review of the literature suggests a lower rate of cage subsidence after lumbar interbody fusion using bridging cages rather than single cages.