T. Vendeuvre

Evaluation of percutaneous surgery in the treatment of thoracolumbar fractures. Preliminary results of a prospective study on 65 patients

INTRODUCTION We conducted a prospective, single-center, continuous study of patients operated for fractures urelated to osteoporosis at the thoracolumbar junction level using percutaneous techniques. The aim of this study was to investigate the clinical and radiological outcomes of percutaneous techniques for these indications. PATIENTS AND METHODS This study included patients who underwent standalone balloon kyphoplasty surgery or combined with percutaneous posterior osteosynthesis in cases of associated distraction. The fractures were classified according to the Magerl classification. The patients were evaluated clinically (visual analog scale [VAS], the Oswestry Disability Index, and autonomy) and radiologically (vertebral kyphosis and height variations of the vertebral body) for 12 months. RESULTS Sixty-five patients were included. The mean age at the time of the surgery was 45.4 years (range, 19-72 years). The main indications were A.1 fractures of L1. We noted 22% cement leakages, none having a clinical impact. In the overall series, the VAS at the lesional level improved from 5.5 (range, 3-8) preoperatively to 0.6 (range, 1-3) at 12 months. In all, 95% of the workers resumed their occupation. Traumatic kyphosis improved from 13.3° (range, 5-23°) before the surgery to 8.3° (range, 1-20°). DISCUSSION The complication rate was low. The radiological results are comparable to those reported in the literature for other series with percutaneous surgery. Only the loss of the correction observed in the group undergoing standalone kyphoplasty with calcium phosphate cement led us to propose another type of treatment for these indications. This study must be continued over the long term to detect the appearance of discopathy related to cement leakage and to answer questions as to how cement evolves. LEVEL OF EVIDENCE III, prospective study with low statistical power.

Acrylic kyphoplasty in recent nonosteoporotic fractures of the thoracolumbar junction: a prospective clinical and 3D radiologic study of 54 patients.

Study Design: Prospective clinical and radiological study. Objectives: To evaluate the impact of stand-alone acrylic kyphoplasty in the treatment of recent traumatic fractures of the thoracolumbar spine in young patients. Summary of Background Data: The management of fractures of the thoracolumbar spine without neurological deficit remains controversial. For a long time clinicians could only chose between functional treatment, orthopedic treatment, and traditional surgery. The recent advent of minimally invasive surgical techniques is an interesting alternative. Materials and Methods: Fifty-four patients with a mean age of 45.8±18.2 years and who had recently sustained a fracture of the thoracolumbar junction were enrolled into the study. Balloon kyphoplasty was performed using acrylic cement. Radiologic assessments (computed tomography scans) and clinical assessments (including Visual Analog Scale and Oswestry Disability Index scores) were used to determine kyphoplasty success and measure patient recovery over 2 years. Results: Kyphoplasty reduced mean vertebral kyphosis from 12.8±5.0 degrees at trauma to 8.2±5.1 degrees at 2-year follow-up. Mean vertebral kyphosis was corrected by −5.7±4.7 degrees (P=0.0001) at the point of first verticalization, with no significant change at the 2-year follow-up visit (+1.1±4.3 degrees, P=0.1058). Kyphoplasty significantly augmented the height of the 6 anterior and intermediate segments. Maximum mean augmentation of intermediate vertebral height after 6 months was (11.6%±15.5%, P<0.0001). Patients tolerated the procedure well and 56% of them returned to work 3 months after kyphoplasty. Conclusion: Kyphoplasty is safe and effective in the correction of nonosteoporotic fractures of the thoracolumbar junction in young patients, and remains stable for at least 2 years postsurgery.

Tuberoplasty: Minimally invasive osteosynthesis technique for tibial plateau fractures

Fractures of the tibial plateau are in constant progression. They affect an elderly population suffering from a number of comorbidities, but also a young population increasingly practicing high-risk sports and using two-wheeled vehicles. The objective of this study was therefore to propose a new technique for the treatment of this type of fracture. There are a variety of classical pitfalls of conservative treatment such as defective reduction resulting in early osteoarthritis and alignment defects. Conventional treatments lead to joint stiffness and amyotrophy of the quadriceps, caused by the open technique and late loading. We propose an osteosynthesis technique for tibial plateau fractures with minimally invasive surgery. A minimally invasive technique would be more appropriate to remedy all of the surgical drawbacks resulting from current practices. The surgical technique that we propose uses a balloon allowing progressive and total reduction, associated with percutaneous screw fixation and filling with polymethylmethacrylate (PMMA) cement. The advantages are optimal reduction, minimal devascularization, soft tissues kept intact, as well as early loading and mobilization. This simple technique seems to be a good alternative to conventional treatment. The most comminuted fractures as well as the most posterior compressions can be treated, while causing the least impairment possible. Arthroscopy can be used to verify fracture reduction and cement leakage. At the same time, it can be used to assess the associated meniscal lesions and to repair them if necessary.

Utility of cement injection to stabilize split-depression tibial plateau fracture by minimally invasive methods: A finite element analysis

Background: Treatment for fractures of the tibial plateau is in most cases carried out by stable fixation in order to allow early mobilization. Minimally invasive technologies such as tibioplasty or stabilization by locking plate, bone augmentation and cement filling (CF) have recently been used to treat this type of fracture. The aim of this paper was to determine the mechanical behavior of the tibial plateau by numerically modeling and by quantifying the mechanical effects on the tibia mechanical properties from injury healing. Methods: A personalized Finite Element (FE) model of the tibial plateau from a clinical case has been developed to analyze stress distribution in the tibial plateau stabilized by balloon osteoplasty and to determine the influence of the cement injected. Stress analysis was performed for different stages after surgery. Findings: Just after surgery, the maximum von Mises stresses obtained for the fractured tibia treated with and without CF were 134.9 MPa and 289.9 MPa respectively on the plate. Stress distribution showed an increase of values in the trabecular bone in the treated model with locking plate and CF and stress reduction in the cortical bone in the model treated with locking plate only. Interpretation: The computed results of stresses or displacements of the fractured models show that the cement filling of the tibial depression fracture may increase implant stability, and decrease the loss of depression reduction, while the presence of the cement in the healed model renders the load distribution uniform. Highlights:A patient‐dependent finite element model from a clinical case has been developed.A biomechanical analysis of cement contribution on a stabilized personalized model of tibiaStress distribution in bone structures was analyzed according to stabilization solutions.Stress distribution was studied a different stages of healing process.

Contribution of minimally invasive bone augmentation to primary stabilization of the osteosynthesis of Schatzker type II tibial plateau fractures: Balloon vs bone tamp

Background: Schatzker type II tibial plateau fractures necessitate the least invasive treatment possible. Arthroscopic reduction by bone tamp followed by osteosynthesis is the current gold standard for this type of tibial plateau fracture. The objective of this study was to compare this technique to anterior approach tuberoplasty with balloon reduction. The comparison criteria were residual articular step off, metaphyseal cavity volume formed during reduction, and mechanical strength to separation and to depression displacement. Methods: Fractures were created on 12 human cadaveric tibiae and reduced by a minimally invasive approach in six specimens by a balloon, and by bone tamp in the six others. Articular step off and metaphyseal‐epiphyseal cavity volume were measured by TDM. Mechanical tests were performed up to assembly failure to characterize structural strength. Secondary displacements, fracture depression displacement and separation were measured by optical methods. Findings: There was no significant difference in step off measurement after balloon reduction or bone tamp (0.29 cm vs 0.37 cm; p = 0.06). The cavity volume formed by balloon reduction was significantly smaller than the volume created by bone tamp reduction (0.45 cm3 vs 5.12 cm; p = 0.002). The compressive load required for assembly failure was significantly greater in the balloon group than in the bone tamp group (1210.17 N vs 624.50 N; p = 0.015). Interpretation: There exists a correlation between load to failure of the assembly frame and the metaphyseal volume required for bone fracture reduction. The minimally invasive balloon technique has fewer negative effects on the osseous stock, thereby enabling better primary structural strength of the fracture.

Biomechanical analysis of the thoracolumbar spine under physiological loadings: Experimental motion data corridors for validation of finite element models

Biomechanical studies that involve normal, injured or stabilized human spines are sometimes difficult to perform on large samples due to limited access to cadaveric human spines and biological variability. Finite element models alleviate these limitations due to the possibility of reusing the same model, whereas cadaveric spines can be damaged during testing, or have their mechanicals behaviour modified by fatigue, permanent deformation or structural failure. Finite element models need to be validated with experimental data to make sure that they represent the complex mechanical and physiological behaviour of normal, injured and stabilized spinal segments. The purpose of this study is to characterize the mechanical response of thoracolumbar spine segments with an analytical approach drawn from experimental measurements. A total of 24 normal and fresh cadaveric thoracolumbar spine segments (T11–L3), aged between 53 and 91 years, were tested in pure flexion/extension, lateral bending and axial torsion using a specific experimental setup. Measurements of global and intervertebral angle variations were performed using three-dimensional mark tracking methods. Load/angle curves for each loading were fitted by a logarithmic approach with two coefficients. The coefficients for the functions describing the response of the spinal segments are given and constitute predictive models from experimental data. This work provides data corridors of human thoracolumbar spine motion segments subjected to pure bending in the three physiological planes. These data could be very useful to validate finite element models of the human spine.

Finite element analysis of mechanical behavior of stabilization techniques for tibial plateau fractures

adepartment of mechanical engineering, Faculty of technology sciences, university of mentouri BrothersConstantine, Constantine, algeria; binstitut pprime upr 3346, Cnrs – université de poitiers – isae-ensma, France; caBs lab, université de poitiers, France; ddepartment of neurosurgery, prismatics lab, Chu, poitiers, France; edepartment of orthopaedic surgery and traumatology, Chu, poitiers, France

Biomechanical analysis of different cross-link configurations spinal instrumentation systems: a preliminary study

Percutaneous techniques were initially developed in the management of thoraco-lumbar fractures. Initially transmucular systems have been developed, which generally provide less muscle trauma, blood loss and surgical time. They also benefit from a reduction in the duration of hospitalization, a lower rate of infection, and a reduction in postoperative pain. Nevertheless, there is no system of crosslink binding in these minimally invasive approaches, and those, which are vectors of pain and discomfort from a clinical point of view (Skovrlj 2015). Crosslinks are often used clinically as part of spinal instrumentation, but relatively little basic biomechanical research has been done in terms of their contribution. Dick et al. (1997) used a synthetic spine of polyurethane and reported that stiffness with the concomitant use of transverse systems increased by 60% in axial rotation, but that no increase in flexion, extension or lateral inclination were Observed. Conversely, Lynn et al. (1997) performed cadaveric biomechanics showing that concurrent use of crosslinks increased stiffness not only in rotation but also in lateral flexion. Our study aims to determine the contribution of one or two transverse devices in a short assembly, for which the results are very variable in the literature and if it is necessary to develop percutaneous.

Development of an experimental model of burst fracture with damage characterization of the vertebral bodies under dynamic conditions

Background: Burst fractures represent a significant proportion of fractures of the thoracolumbar junction. The recent advent of minimally invasive techniques has revolutionized the surgical treatment of this type of fracture. However mechanical behaviour and primary stability offered by these solutions have to be proved from experimental validation tests on cadaveric specimens. Therefore, the aim of this study was to develop an original and reproducible model of burst fracture under dynamic impact. Methods: Experimental tests were performed on 24 cadaveric spine segments (T11‐L3). A system of dynamic loading was developed using a modified Charpy pendulum. The mechanical response of the segments (strain measurement on vertebrae and discs) was obtained during the impact by using an optical method with a high‐speed camera. The production of burst fracture was validated by an analysis of the segments by X‐ray tomography. Findings: Burst fracture was systematically produced on L1 for each specimen. Strain analysis during impact highlighted the large deformation of L1 due to the fracture and small strains in adjacent vertebrae. The mean reduction of the vertebral body of L1 assessed for all the specimens was around 15%. No damage was observed in adjacent discs or vertebrae. Interpretation: With this new, reliable and replicable procedure for production and biomechanical analysis of burst fractures, comparison of different types of stabilization systems can be envisaged. The loading system was designed so as to be able to produce loads leading to other types of fractures and to provide data to validate finite element modelling. HIGHLIGHTSA specific experimental dynamic setup for spinal loading has been developed.A biomechanical analysis was performed during impact on spines from a dynamic optical method.Mechanical effects of a dynamic impact on spine were characterized by X‐ray imaging and optical analysis.A reproducible model of burst fracture on human cadaveric specimens was developed.

Biomechanical analysis of spinal instrumentation systems dedicated to stabilise thoracolumbar fractures: comparison between standard open surgical instrumentation and percutaneous techniques

Thoracolumbar burst fractures represent an important part of spine injuries. Burst fractures are usually caused by dynamic axial compression of spine segments. This leads to an inherent instability and then a spinal cord compression. A surgical treatment is needed for most of the cases to restore bone stability, prevent neurological deterioration and provide pain relief. Classically, posterior instrumentations using rods and pedicle screws are performed under open surgical approaches and eventually associated with corpectomy and/or anterior fixation, in case of anterior column threatening instability. However, the choice of the type of surgery might progressively change in favour of minimally invasive techniques. Indeed, burst fracture stabilization using a short posterior instrumentation and/or vertebral balloon expansion followed by an injection of cement (kyphoplasty), with a pure percutaneous approach, can help to reduce morbidity for these patients. However some keypoints need to be clarified about these techniques with a focus on their biomechanical effectiveness. The purpose of this study was to compare mechanical behaviour under physiological loadings of four types of stabilizations devices, including 2 open instrumentations and 2 percutaneous techniques: classical Posterior Fixation standalone (PF); Posterior Fixation associated with anterior screwed Cage-Plate, following a corpectomy of the fractured vertebra (PF-CP); percutaneous Kyphoplasty standalone (K); percutaneous Kyphoplasty and Posterior Fixation (K-PF).