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Publications and source records attributed to Jorrit-Jan Verlaan.
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STUDY DESIGN: The position of a needle tip displayed on a navigation system after transpedicular introduction into a vertebral body is compared with the real position of the needle tip when using a direct navigation coupling between a three-dimensional rotational X-ray (3DRX) system and a navigation system. OBJECTIVES: To assess whether the needle tip position displayed by the navigation system corresponds to the real needle position and to quantitatively determine needle navigation accuracy in a clinically relevant setting. SUMMARY OF BACKGROUND DATA: Image-guided navigation has reportedly increased the accuracy and safety of pedicle screw insertion and decreased complication rates. In former studies, the result of image-guided navigation was mainly compared qualitatively with the result of conventional fluoroscopy-guided procedures. Previously, a direct navigation coupling between a 3DRX system and a standard navigation system was introduced that bypasses the need for explicit patient-to-image registration necessary for image-guided orthopedic surgery. In a phantom experiment, the reported accuracy of navigation with the coupling to a 3DRX system was approximately 1 mm. However, in a clinical setting, additional errors can be introduced. METHODS: Twenty-three needles were placed transpedicularly into vertebral bodies of embalmed human trunks using 3DRX-guided navigation. The navigated needle tip positions were compared with the real needle tip positions manually extracted from 3DRX volumes acquired after completion of the introduction. RESULTS: The average distance between the navigated needle tip and the real position of the needle tip extracted from a postprocedure 3DRX volume was 2.5 +/- 1.5 mm. CONCLUSIONS: Accuracy of 3DRX-guided navigation is 2.5 +/- 1.5 mm in a clinically relevant setting, which is less than the accuracy determined in phantom experiments.
STUDY DESIGN: Review of human cadaveric and in vivo animal studies and clinical trial. OBJECTIVE: To develop less invasive surgical techniques for reconstruction of the anterior column in thoracolumbar fractures. SUMMARY OF BACKGROUND DATA: Persistent central endplate depression can cause anterior column insufficiency after posterior surgery for traumatic thoracolumbar fractures. Reduction of the central endplate followed by intravertebral cement augmentation could restore weight-bearing capacity. MATERIALS AND METHODS: In human cadaveric burst fracture models, balloon-assisted endplate reduction (BAER) and vertebroplasty techniques have been investigated in terms of their safety and biomechanical properties. The histologic properties of different cement polymers were studied in an animal vertebral body and endplate defect model. In addition, the clinical outcome of percutaneous cement augmentation in the setting of a burst fracture examining the BAER technique and vertebroplasty with adjunctive posterior pedicle screw fixation is reviewed. RESULTS: These techniques have proven to be safe and effective, although cement leakage outside the confines of the vertebral body may occur. Calcium phosphate cements are preferable over methylmethacrylate because of their in vivo histologic properties. Using the BAER technique and posterior pedicular fixation, anterior vertebral height restoration is possible. Following balloon removal, some loss of fracture height restoration is observed. Further loss of vertebral height reduction was not observed following cement curing clinically. CONCLUSIONS: These studies show that less invasive anterior vertebral reconstruction using percutaneous cement augmentation techniques is feasible following traumatic vertebral fractures.
PURPOSE: To investigate the feasibility of navigation with three-dimensional (3D) rotational radiographic data for transpedicular percutaneous needle introduction and to compare navigation with 3D rotational radiographic data with conventional fluoroscopic guidance. MATERIALS AND METHODS: A navigation system was coupled to a 3D rotational radiographic imaging system. In a cadaver study, 60 biopsy needles were introduced into vertebral bodies with fluoroscopic guidance or navigation with 3D rotational radiographic data by two interventionalists with different levels of experience in percutaneous procedures. Radiation exposure, fluoroscopy and introduction times, and needle position were evaluated and compared. RESULTS: For 3D rotational radiographic navigation, the needle position was equivalent for both interventionalists (7 mm). For fluoroscopic guidance, the interventionalist with less experience in percutaneous procedures had significantly more pedicle cortex violations than the other interventionalist (eight vs one). Radiation exposure measured at the operators' hand was lower for 3D rotational radiography-guided needle introductions. Radiation exposure measured at the body wall of the cadaver was equivalent between modalities (9 mGy). CONCLUSIONS: Navigation with 3D rotational radiographic image data is feasible for transpedicular percutaneous needle introduction and has two advantages compared with fluoroscopic guidance: it poses less strict requirements on the expertise of the interventionalist, and it reduces radiation exposure to the interventionalist.
A vertebral fracture, whether originating from osteoporosis or trauma, can be the cause of pain, disability, deformation and neurological deficit. The treatment of vertebral compression fractures has, for many years until the advent of vertebroplasty, consisted of bedrest and analgesics. Vertebroplasty is a percutaneous technique during which bone cement is injected in a vertebral body to provide immediate pain relief by stabilization. Inflatable bone tamps can, prior to the injection of cement, be used to create a void in the vertebral body, in which case the technique is known as balloon vertebroplasty (or kyphoplasty). The chance of extracorporal cement leakage is smaller for balloon vertebroplasty than for vertebroplasty. Some authors also claim to have gained some correction in vertebral body height or angulation. Both interventions can be used for several indications, including osteoporotic compression fractures and osteolytic lesions of the vertebral body such as myeloma, hemangioma or metastasis, and also for traumatic burst fractures in combination with pedicle screw instrumentation. Polymethyl methacrylate cement is the bone void filler that is used most frequently, although the application of calcium phosphate cements has been studied widely in vitro, in vivo and also in small-scale clinical series. The clinical results of (balloon-) vertebroplasty are favorable with 85-95% of all patients experiencing immediate and long-lasting relief of pain. Serious complications are relatively rare but include neurological deficit and pulmonary embolism. In this paper, both vertebroplasty and balloon vertebroplasty and their respective indications, techniques and results are described in relation with the application and limitations of permanent and resorbable injectable bone cements.
STUDY DESIGN: In a human cadaveric burst fracture model, the amount of endplate fracture reduction after posterior instrumentation and balloon vertebroplasty was investigated quantitatively. OBJECTIVES: To assess, in a burst fracture model, the vertebral body and adjacent disc heights, in parallel sagittal planes with 3-dimensional (3D) rotational x-ray imaging, at various phases during pedicle screw fixation and subsequent balloon vertebroplasty. SUMMARY OF BACKGROUND DATA: In recent human cadaveric thoracolumbar fracture studies, it was found that vertebral body height could be restored significantly with inflatable bone tamps. However, limited quantitative data exist on the amount of fracture reduction that can be achieved and how much of the reduction will be lost after deflation and removal of the bone tamps before the cement is injected. METHODS: Twenty burst fractures were created and balloon vertebroplasty with calcium phosphate cement was performed after pedicle screw instrumentation. A 3D dataset was obtained during the following phases: intact, fractured, after reduction and stabilization with pedicle screws, after inflation of the balloons, after deflation and removal of the balloons, after injection of the cement. The fractured vertebral body and adjacent disc heights were measured from five reconstructed sagittal images and compared for the six phases of the procedure. Furthermore, the difference between the vertebral body height centrally and peripherally was calculated. RESULTS: The mean vertebral body height at the thoracic level was Tintact = 19.5 +/- 2.2 mm, Tfractured = 14.6 +/- 3.8 mm, Treduction = 17.3 +/- 2.2 mm, Tinflation = 20.1 +/- 2.0 mm, Tdeflation = 18.0 +/- 2.0 mm, and Tcement = 17.8 +/- 1.8 mm. The overall change in vertebral body height between these phases was significant (P < 0.001). At the lumbar level the mean vertebral body height was Tintact = 23.2 +/- 3.8 mm, Tfractured = 14.7 +/- 3.0 mm, Treduction = 18.4 +/- 2.5 mm, Tinflation = 23.2 +/- 3.5 mm, Tdeflation = 19.3 +/- 2.3 mm, and Tcement = 20.2 +/- 2.8 mm. The overall change in MCVBH between these phases was also significant (P < 0.001). The increase in vertebral body height resulted in a decrease of the adjacent disc height. No difference was found for the amount of endplate reduction in the center or at the periphery. No leakage of cement was detected in the spinal canal. CONCLUSIONS: Reduction of endplate fractures, both in the center and at the periphery, seems feasible and safe with combined fracture reduction and balloon vertebroplasty. The endplate fracture reduction that was gained by inflation of the bone tamps could not be maintained after deflation.
STUDY DESIGN: In a human cadaveric burst fracture model with and without longitudinal ligament damage, the amount of anterior and posterior bone displacement (ABD, PBD) during balloon vertebroplasty after pedicle-screw instrumentation was investigated quantitatively. OBJECTIVES: To investigate, in a burst fracture model with and without longitudinal ligament damage, the amount of ABD, PBD, and cement leakage at various phases during balloon vertebroplasty in combination with pedicle-screw instrumentation. SUMMARY OF BACKGROUND DATA: The role of intact longitudinal ligaments in traumatic spine fractures, for prevention of bone retropulsion and subsequent reduction, has been discussed in several studies but is still up for debate. In a recent human cadaveric burst fracture study, inflatable bone tamps and calcium phosphate cement were used for the augmentation of the anterior column after pedicle-screw instrumentation. The additional balloon vertebroplasty procedure was found to be feasible and safe, but no data pertaining to unwarranted bone displacement or cement leakage during the procedure are available for burst fractures with damaged longitudinal ligaments. METHODS: Ten thoracic and 10 lumbar burst fractures, with rotation or flexion components, were created, and balloon vertebroplasty with calcium phosphate cement was performed after pedicle-screw instrumentation. Volumetric datasets (using the 3-dimensional (3D) rotational x-ray imaging technique) of the fractures were obtained during the following phases: intact, fractured, after reduction and stabilization with pedicle-screws, after inflation of the balloons, after deflation and removal of the balloons, and after injection of the cement. The amount of ABD and PBD was measured on reconstructed sagittal images and recorded together with the presence of extracorporal cement leakage. The continuity of the longitudinal ligaments was assessed after anatomic dissection. RESULTS: During the balloon vertebroplasty procedure, a significant (P < 0.05) increase of ABD (at both thoracic and lumbar level) and PBD (thoracic level) occurred after inflation of the balloons. After deflation and subsequent injection of the cement, however, the ABD and PBD returned to the preinflation levels. The absolute amount of ABD and PBD (<1 mm) during inflation was considered of little clinical importance. No differences in ABD or PBD were observed for specimens with or without continuity of the corresponding longitudinal ligament, irrespective of the level, at any of the phases during the experiment (P > 0.5 in all cases). A small amount of cement leakage was observed in the psoas compartment of one specimen with intact longitudinal ligaments. CONCLUSIONS: It is suggested that balloon vertebroplasty after pedicle-screw instrumentation may safely be used, in terms of bone displacement and cement leakage, in fracture types where damage to longitudinal ligaments is to be expected.
STUDY DESIGN: A validation study was done in which reconstructed three-dimensional rotational x-ray images were quantitatively compared with corresponding anatomic sections. OBJECTIVES: To assess the accuracy of reconstructed images acquired on a three-dimensional rotational x-ray imaging device. SUMMARY OF BACKGROUND DATA: Minimally invasive procedures have proven quite successful as alternatives for a multitude of open treatments. An unfavorable property of this type of procedure is a lack of direct vision of the operating area. Three-dimensional rotational x-ray imaging may be able to merge the advantages of computed tomography and fluoroscopy: real-time two-dimensional projections for fast visual feedback and three-dimensional reconstructions for detailed volumetric imaging of complex anatomy. METHODS: Twenty traumatic thoracolumbar burst fractures were created and underwent pedicle screw instrumentation and balloon vertebroplasty. Subsequently, a three-dimensional dataset was obtained, and the midsagittal image was reconstructed. The specimens were sliced, and photographs were obtained. Multiple parameters on the reconstructed images and photographs were measured two times by two observers using a graphical method. The differences and standard deviations were calculated for the corresponding parameters and for the intraobserver data. RESULTS: The mean difference between the corresponding values ranged between -1.1 and 2.1 mm for all parameters. The standard deviation for the differences per parameter ranged between 1.2 and 3.2 mm. The intraobserver differences ranged from -0.8 to 1.4 mm, and the standard deviation varied between 0.4 and 2.4 mm. CONCLUSIONS: The reconstructed midsagittal images were accurate in all measured parameters. The three-dimensional rotational x-ray technique may prove to be valuable for less invasive spine surgery.
STUDY DESIGN: Clinical trial (phase II). OBJECTIVES: To assess the feasibility and safety of balloon vertebroplasty after posterior short-segment reduction and fixation for the treatment of traumatic burst fractures. SUMMARY OF BACKGROUND DATA: Hardware failure and loss of reduction after posterior short-segment instrumentation are complications caused by insufficiency of anterior column support. This is due to migration of disc tissue through the endplate into the fractured vertebral body that cannot be restored with posterior instrumentation. METHODS: Patients with traumatic thoracolumbar burst fractures without neurologic deficits were included. After posterior reduction and fixation, bilateral transpedicular balloon reduction of the endplate was performed, and calcium phosphate cement was injected. Preoperative and postoperative Cobb angle and central and anterior height were assessed with radiographs and MRI. RESULTS: Twenty patients underwent surgery without technical difficulties, and a substantial reduction of the endplates could be achieved with the technique. All patients recovered uneventfully, and the neurologic examination revealed no deficits. The postoperative radiographs and magnetic resonance images demonstrated a good fracture reduction and filling of the bone defect without unwarranted bone displacement. The central and anterior height of the vertebral body could be restored to 78 and 91% of the estimated intact height, respectively. Complications were cement leakage in five cases without clinical implications and one wound hematoma. CONCLUSIONS: Transpedicular balloon vertebroplasty for the direct restoration of burst fractures seems feasible in combination with posterior instrumentation. Cement leakage occurred but had no clinical consequences.
Posterior short-segment pedicle screw constructs are commonly used for reduction and fixation of traumatic thoracolumbar spine fractures. Although this technique is usually simple and effective, complications such as loss of fixation or recurrence of deformity are common because of the insufficiency of the damaged anterior column. Anterior approaches to address this deficiency are associated with high morbidity and complications. We have developed a technique to reduce and support the fractured anterior column through a transpedicular approach. Balloon-assisted-endplate-reduction (BAER) followed by vertebroplasty (VTP) with calcium phosphate cement in combination with short segment pedicle screw construct seem to be a safe and effective technique to reconstruct the anterior column in a less invasive manner. In this article, the rationale behind this technique, experimental studies, and the first clinical results are discussed.
The most widely used imaging devices in trauma spine surgery are fluoroscopy and computed tomography. Both techniques have their specific pros and cons and expose both patient and operating staff to considerable radiation during image acquisition. Three-dimensional-rotational x-ray imaging (3-DRX) is a relatively new technique in which a C-arm is moved around the patient to allow for an "acquisition run" during which multiple fluoroscopy images are obtained. The images can subsequently be processed on a workstation into a 3-D volume, which can then be manipulated in a similar way to 3-D computed tomography data. The 3-DRX technique combines the advantages of both fluoroscopy and computed tomography: fast visual feedback and high resolution multiplanar reformatted images, respectively, and could be used in an intraoperative setting. In this paper some technical aspects of 3-DRX imaging and its potential role in spinal trauma treatment are presented.
STUDY DESIGN: Magnetic resonance (MR) and three-dimensional rotational x-ray (3DRX) images of cadaveric spinal segments were registered using a conventional point-based technique and a noninvasive technique called maximization of mutual information (MMI). OBJECTIVES: To assess the feasibility and accuracy of MMI-based registration in comparison with point-based registration as a new noninvasive image-to-patient registration technique for use in minimally invasive image-guided spine surgery. SUMMARY OF BACKGROUND DATA: In image-guided orthopedic surgery, correspondence between before surgery acquired images and the patient is required. Currently, this necessitates an invasive registration step, in which anatomic landmarks on the bone surface have to be physically touched by a pointer. To overcome this invasive procedure, we propose using a calibrated 3DRX system, a modality that can visualize high contrast objects intraoperatively and that provides a direct correspondence between the image data and the patient. A noninvasive voxel-based technique is used to register the intraoperative 3DRX image to a before surgery acquired MR image. METHODS: Cadaveric thoracic and lumbar spine segments were implanted with markers, which were used as landmarks. The accuracy of the landmark-based registration was compared with MMI-based registration using the residual errors on the marker positions. RESULTS: The errors made using the point-based registration technique were compared with the errors made with MMI. The results show a statistically significant lower error (P < 0.01) for the proposed MMI method. CONCLUSIONS: Noninvasive MMI registration of intraoperative 3DRX images to preoperative MR images is more accurate than point-based registration in cadaveric spine segments. It is therefore a promising technique for replacing the invasive landmark-based registration that is currently used in image-guided spine surgery.
Although the general complication rate for vertebroplasty is low, neural compression and thermal damage have been related to the use of polymethyl-methacrylate cement. This study focuses on the risk of thermal tissue damage after vertebroplasty. In this study, cavities were created by a transpedicular approach in the vertebral bodies (L3, L4, and L5) of four milk goats, and polymethyl-methacrylate cement was injected. In three locations (the bone-cement interface, the epidural space, and the disc space) the temperature was measured in regular intervals after injection of the cement. The mean injected volume was 0.8 ml, which accounted for a 22% volume fraction. The mean peak temperature of the bone-cement interface was 44.6 degrees C, while the maximum temperature at the epidural space and disc space was 37.0 and 37.5 degrees C, respectively. The local temperature measured after in vivo vertebroplasty did not reach values that are known to cause tissue necrosis.