Ulrich Berlemann

Vertebroplasty and kyphoplasty: a systematic review of 69 clinical studies

Study Design. Systematic literature review. Objective. To evaluate the safety and efficacy of vertebroplasty and kyphoplasty using the data presented in published clinical studies, with respect to patient pain relief, restoration of mobility and vertebral body height, complication rate, and incidence of new adjacent vertebral fractures. Summary of Background Data. Vertebroplasty and kyphoplasty have been gaining popularity for treating vertebral fractures. Current reviews provide an overview of the procedures but are not comprehensive and tend to rely heavily on personal experience. This article aimed to compile all available data and evaluate the clinical outcome of the 2 procedures. Methods. This is a systematic review of all the available data presented in peer-reviewed published clinical trials. The methodological quality of included studies was evaluated, and data were collected targeting specific standard measurements. Where possible, a quantitative aggregation of the data was performed. Results. A large proportion of subjects had some pain relief, including 87% with vertebroplasty and 92% with kyphoplasty. Vertebral height restoration was possible using kyphoplasty (average 6.6°) and for a subset of patients using vertebroplasty (average 6.6°). Cement leaks occurred for 41% and 9% of treated vertebrae for vertebroplasty and kyphoplasty, respectively. New fractures of adjacent vertebrae occurred for both procedures at rates that are higher than the general osteoporotic population but approximately equivalent to the general osteoporotic population that had a previous vertebral fracture. Conclusions. The problem with stating definitely that vertebroplasty and kyphoplasty are safe and effective procedures is the lack of comparative, blinded, randomized clinical trials. Standardized evaluative methods should be adopted.

Percutaneous transpedicular vertebroplasty with PMMA: operative technique and early results

Abstract Vertebroplasty-percutaneous cement augmentation of osteoporotic vertebrae is an efficient procedure for the treatment of painful vertebral fractures. From a prospectively monitored series of 70 patients with 193 augmented vertebrae for osteoporotic and metastatic lesions, we analysed a group of 17 patients suffering from back pain due to osteoporotic fractures. The reinforcement of 45 vertebral bodies in these patients led to a significant and lasting pain reduction (P < 0.01). The presented technique is useful, as, in one session, at least four injections can be performed when required, allowing the prophylactic reinforcement of adjacent vertebrae as well. The use of a low-viscosity polymethyl methacrylate (PMMA) in combination with a non-ionic liquid contrast dye provides a reliable and safe procedure. Extraosseous cement leakage was seen in 20% of the interventions; however, none of them had clinical sequelae.

Accuracy of computer-assisted pedicle screw placement : an in-vivo computed tomography analysis

Study Design. A computer‐assisted planning and visualization system (the Orthopaedic Surgery Planning System) was tested for pedicle screw insertion in vivo. Objectives. To evaluate the systems applicability for regular intraoperative use and its accuracy for pedicle screw placement in vivo. Summary of Background Data. Pedicle screw placement poses considerable anatomic and biomechanical risks. The reported rates of screw misplacement with conventional insertion techniques are unacceptably high. It previously has been shown in vitro that computer assistance offers the potential to decrease the number of screws perforating the pedicular cortex. Methods. The accuracy of 162 pedicle screws inserted with the Orthopaedic Surgery Planning System was assessed by means of postoperative computed tomography evaluation. Reconstructions of the horizontal, frontal, and sagittal planes were analyzed. Cortex perforations were graded in steps of 2 mm. Results. The cortex was perforated in 2.7% of pedicles. Complete preoperative computed tomography scanning of the levels to be operated on is essential to allow for a precise image reconstruction. Initial difficulties in applying the system contribute to the malplacements. A learning curve for general handling of the Orthopaedic Surgery Planning System was observed. Conclusions. The system provides a safe and reproducible technique for pedicle screw insertion. Other applications in the field of spine surgery are under evaluation.

Image-guided insertion of transpedicular screws. A laboratory set-up.

Study design A computer-assisted system allowing precise preoperative planning and real-time intraoperative image localization of surgical instruments is tested in a laboratory setup. Objectives The purpose of this study is to assess the applicability, functionality, and accuracy of this transpedicular spinal fixation technique. Summary of background data Most techniques in transpedicular spinal fixation rely on the identification of predefined targets with the help of anatomic landmarks and on the intraoperative use of image intensifiers. Various studies report considerable screw misplacement rates which may lead to serious clinical sequelae such as permanent nerve damage. Methods The proposed system was tested in an in vitro setup drilling 20 pedicle pilot holes in lumbar vertebrae. The accuracy was assessed using precision cuts through the pedicles and simulation of a 6-mm pedicle screw insertion. Results An ideal screw position was found in 70 of 77 cuts, and in no case was an injury to the pedicular cortex observed. Conclusions The presented technique provides a safe, accurate, and flexible basis for transpedicular screw placement in the spine. This approach should be further evaluated in clinical applications.

Kyphoplasty for treatment of osteoporotic vertebral fractures: a prospective non-randomized study.

BackgroundMinimally invasive augmentation techniques of vertebral bodies have been advocated to treat osteoporotic vertebral body compression fractures (VBCFs). Kyphoplasty is designed to address both fracture-related pain as well as kyphotic deformity usually associated with fracture. Previous studies have indicated the potential of this technique for reduction of vertebral body height, but there has been little investigation into whether this has a lasting effect. The current study reports on our experience and the one-year results in 27 kyphoplasty procedures (24 patients) for osteoporotic VBCFs.ResultsAll but one patient experienced pain relief following the procedure (on VAS 1–10)—with a lasting effect over the follow-up period in 25 cases. An average vertebral kyphosis reduction of 47.7% was achieved with no loss of reduction after one year. The potential for reduction was statistically related to the pre-operative amount of kyphosis, the level treated, and the age of the fracture, but not to the age of the patient. During follow-up, one fracture adjacent to a treated level was observed. Pain relief was not related to the amount of reduction.ConclusionKyphoplasty is an effective treatment of VBCFs in terms of pain relief and durable reduction of deformity. Whether spinal realignment results in an improved long-term clinical outcome remains to be investigated.

Bone substitutes in vertebroplasty

Abstract. Vertebroplasty – percutaneous cement augmentation of vertebral bodies – is an efficient procedure for the treatment of painful vertebral fractures in osteoporosis. At the present time, polymethylmethacrylate (PMMA) is the only available cement with reports of clinical application and experience. The material is easy to handle, the radiopacity can be adapted by adding contrast dye, and it is mechanically efficient. Composite cements (acrylic cements in conjunction with ceramics) are bioactive, highly radiopaque, and feature excellent mechanical properties. One such cement, Cortoss, is currently undergoing clinical trials for vertebroplasty and has so far been shown to be a potentially valuable alternative to PMMA. Several in vitro studies with injectable calcium phosphate (CaP) cements show their feasibility and mechanical effectiveness. Animal studies confirm their biocompatibility and osteoconductivity. However, handling problems and the limited radiopacity of these cements currently preclude their clinical use.

A new approach to computer-aided spine surgery: fluoroscopy-based surgical navigation.

Abstract A new computer-based navigation system for spinal surgery has been designed. This was achieved by combining intraoperative fluoroscopy-based imaging using conventional C-arm technology with freehand surgical navigation principles. Modules were developed to automate digital X-ray image registration. This is in contrast to existing computed tomography- (CT) based spinal navigation systems, which require a vertebra-based registration procedure. Cross-referencing of the image intensifier with the surgical object allows the real-time image-interactive navigation of surgical tools based on one single registered X-ray image, with no further image updates. Furthermore, the system allows the acquisition and real-time use of multiple registered images, which provides an advanced multi-directional control (pseudo 3D) during surgical action. Stereotactic instruments and graphical user interfaces for image-interactive transpedicular screw insertion have been developed. A detailed validation of the system was performed in the laboratory setting and throughout an early clinical trial including eight patients in two spine centers. Based on the resulting data, the new technique promises improved accuracy and safety in open and percutaneous spinal surgery.

Treatment of thoracolumbar burst fractures without neurologic deficit by indirect reduction and posterior instrumentation: bisegmental stabilization with monosegmental fusion

Abstract This study retrospectively reviews 20 sequential patients with thoracolumbar burst fractures without neurologic deficit. All patients were treated by indirect reduction, bisegmental posterior transpedicular instrumentation and monosegmental fusion. Clinical and radiological outcome was analyzed after an average follow-up of 6.4 years. Re-kyphosis of the entire segment including the cephaled disc was significant with loss of the entire postoperative correction over time. This did not influence the generally benign clinical outcome. Compared to its normal height the fused cephalad disc was reduced by 70% and the temporarily spanned caudal disc by 40%. Motion at the temporarily spanned segment could be detected in 11 patients at follow-up, with no relation to the clinical result. Posterior instrumentation of thoracolumbar burst fractures can initially reduce the segmental kyphosis completely. The loss of correction within the fractured vertebral body is small. However, disc space collapse leads to eventual complete loss of segmental reduction. Therefore, posterolateral fusion alone does not prevent disc space collapse. Nevertheless, clinical long-term results are favorable. However, if disc space collapse has to prevented, an interbody disc clearance and fusion is recommended.

Early histologic changes in lower lumbar discs and facet joints and their correlation.

Abstract Biomechanical and histologic studies have highlighted the close functional relationship between lumbar discs and their associated facet joints, and it is conceivable that their degenerative changes are interdependent. However, separation of cause from effect remains controversial. Hitherto, no study in humans has correlated the changes histologically. The present study assessed histologic changes in lower lumbar discs and their associated facet joints in patients under the age of 40 years using classification systems developed for this investigation. A specific objective was to correlate changes in discs and facet joints. Data from 15 lower lumbar spine specimens were obtained. Three parasagittal sections per disc and one section per facet joint were graded histologically. The results were correlated with age, within the functional spinal unit (FSU), and with the adjacent level. Histologic changes were found in discs and facet joints from all FSUs. There was no correlation between the age of the subject and the degree of degeneration of the disc or facet joints at either level. The extent of disc degeneration at L4/5 correlated significantly with changes at L5/S1 (P < 0.01). There was no correlation between changes in discs and the associated facet joints at either level. The results of the study showed that microscopic changes are seen in the disc and facet joints from an early age and can be quite marked in some individuals before the age of 40 years. A correlation of degenerative changes within the FSU could not be established.

The relationship between height, shape and histological changes in early degeneration of the lower lumbar discs

Abstract The influence of aging and early degenerative changes on intervertebral disc height is controversial. It has been claimed that with aging, narrowing of the disc is inevitable, but this is not confirmed by some published radiological investigations. The present study analysed the height and shape of intervertebral discs from subjects younger than 40 years, and correlated the findings with histological alterations, which were assessed using a grading system. Discs from the L4/5 level (n = 13) and the L5/S1 level (n = 10) were included. Degenerative changes tended to increase with age, specifically at the L4/5 level. There was a weak trend towards decreased disc height with increasing degenerative changes, but no significant correlation could be found. Disc shape was more convex in the frontal than the sagittal plane. It is concluded that early histological changes do not significantly influence intervertebral disc height. More pronounced loss of disc height may be seen in advanced degenerative changes or in elderly subjects.