Recent trends, technical concepts and components of computer-assisted orthopedic surgery systems: A comprehensive review

Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.Web of Science1923art. no. 519

The International Research Society of Spinal Deformities (IRSSD) and its contribution to science

From the time of its initial, informal meetings starting in 1980 to its formal creation in 1990, the IRSSD has met on a bi-annual basis to discuss all aspects of the spine and associated deformities. It has encouraged open discussion on all topics and, in particular, has tried to be the seed-bed for new ideas. The members are spread around the world and include people from all areas of academia as well as the most important people, the patients themselves. Most notably, application of the ideas and results of the research has always been at the forefront of the discussions. This paper was conceived with the idea of evaluating the impact made by the IRSSD over the last 30 years in the various areas and is intended to create discussion for the upcoming meeting in Montreal regarding future focus: "We are lost over the Atlantic Ocean but we are making good time.

Planning the Surgical Correction of Spinal Deformities: Toward the Identification of the Biomechanical Principles by Means of Numerical Simulation

The set of surgical devices and techniques to perform spine deformity correction has widened dramatically. Nevertheless, the rate of complications due to mechanical failure remains rather high. Indeed, basic research about the principles of deformity correction and the optimal surgical strategies (i.e. the choice of the fusion length, the most appropriate instrumentation, the degree of tolerable correction) did not progress as much as the techniques. In this work, a software approach for the biomechanical simulation of the correction of patient-specific spinal deformities aimed to the identification of its biomechanical principles is presented. The method is based on three dimensional reconstructions of the spinal anatomy obtained from biplanar radiographic images. A user-friendly graphical interface allows for the planning of the deformity correction and to simulate the instrumentation. Robust meshing of the instrumented spine is provided by using consolidated computational geometry and meshing libraries. Based on finite element simulation, the program predicts the loads acting in the instrumentation as well as in the biological tissues. A simple test case (reduction of a low grade spondylolisthesis at L3-L4) was simulated as a proof-of-concept. Despite the limitations of this approach, the preliminary outcome is promising and encourages a wide effort towards its refinement

Scoliosis Analog Model for the Evaluation of Bracing Technology

Thoracolumbar braces are commonly used to treat Adolescent Idiopathic Scoliosis (AIS). Braces serve to reduce and prevent progression of the spinal curve by applying corrective forces. The magnitude and direction of these corrective forces applied by the brace to the spine remain unknown. Additionally the brace fitting process involves making alterations to the brace that affect its corrective force capacity. The objective was to design and validate an analog model of a mid-thoracic single curve scoliotic deformity for quantifying structural properties of the brace and the force response of the brace on the spine. This model was used to investigate the effects of strap-related brace design alterations. Additionally, the model was customized and demonstrated to be representative of a clinical case study. A novel mechanically-equivalent analog model of the AIS condition was designed and developed to simulate up to 40 degrees of spinal correction. The linkage-based model was used in conjunction with a biorobotic testing platform to test a scoliosis brace. Measurements of the force components applied to the model and angular displacement of the linkage assembly were used to calculate the brace structural stiffness properties. The brace was tested using two types of straps (Velcro and buckle) applied in various configurations and compared to an unconstrained configuration and rigidly constrained configuration to demonstrate the capacity of the model to study brace design alterations. Calculated stiffness was expressed as a resistive force relative to the angular change of the linkage system. Addition of either strap type significantly increased the stiffness values relative to the unconstrained configuration. An optimal brace radial stiffness was achieved with three Velcro straps, i.e., there was no significant stiffness gained by adding a fourth strap. For the case of the buckle straps, no significant stiffness gain occurred when more buckle straps were added. Structural properties provide a means to compare bracing technology and better understand design features. The testing of design alterations, i.e. variable strap configurations, show a measureable difference in brace force response and structural properties between each configuration. Also, interpretation of the measured force components revealed that the brace applied inward and upward forces to the spine. A novel scoliosis analog model and testing assembly were developed to provide first time measures of the forces applied to the spine by a thoracolumbar brace. In addition to quantifying brace structural properties, this test assembly could be used as a design and testing tool for scoliosis brace technology

3D-printing techniques in a medical setting : a systematic literature review

Background: Three-dimensional (3D) printing has numerous applications and has gained much interest in the medical world. The constantly improving quality of 3D-printing applications has contributed to their increased use on patients. This paper summarizes the literature on surgical 3D-printing applications used on patients, with a focus on reported clinical and economic outcomes. Methods: Three major literature databases were screened for case series (more than three cases described in the same study) and trials of surgical applications of 3D printing in humans. Results: 227 surgical papers were analyzed and summarized using an evidence table. The papers described the use of 3D printing for surgical guides, anatomical models, and custom implants. 3D printing is used in multiple surgical domains, such as orthopedics, maxillofacial surgery, cranial surgery, and spinal surgery. In general, the advantages of 3D-printed parts are said to include reduced surgical time, improved medical outcome, and decreased radiation exposure. The costs of printing and additional scans generally increase the overall cost of the procedure. Conclusion: 3D printing is well integrated in surgical practice and research. Applications vary from anatomical models mainly intended for surgical planning to surgical guides and implants. Our research suggests that there are several advantages to 3D- printed applications, but that further research is needed to determine whether the increased intervention costs can be balanced with the observable advantages of this new technology. There is a need for a formal cost-effectiveness analysis

Surgical GPS Proof of Concept for Scoliosis Surgery

Scoliotic deformities may be addressed with either anterior or posterior approaches for scoliosis correction procedures. While typically quite invasive, the impact of these operations may be reduced through the use of computer-assisted surgery. A combination of physician-designated anatomical landmarks and surgical ontologies allows for real-time intraoperative guidance during computer-assisted surgical interventions. Predetermined landmarks are labeled on an identical patient model, which seeks to encompass vertebrae, intervertebral disks, ligaments, and other soft tissues. The inclusion of this anatomy permits the consideration of hypothetical forces that are previously not well characterized in a patient-specific manner. Updated ontologies then suggest procedural directions throughout the surgical corridor, observing the positioning of both the physician and the anatomical landmarks of interest at the present moment. Merging patient-specific models, physician-designated landmarks, and ontologies to produce real-time recommendations magnifies the successful outcome of scoliosis correction through enhanced pre-surgical planning, reduced invasiveness, and shorted recovery time

Dynamic surface topography and its application to the evaluation of adolescent idiopathic scoliosis

Dynamic surface topography is a method to quantify the surface and locations of features acquired from moving and distorting shapes against time. This thesis describes the application of the technique to the potential evaluation of adolescent idiopathic scoliosis patients. Scoliosis or curvature of the spine is one of the major skeletal diseases in adolescents where in the majority of cases the cause is unknown or idiopathic. The progression of the disease occurs in three dimensions with the spine simultaneously curving towards the arms and rotating as it collapses with the first indications usually being changes in body symmetry and back surface shape. Following diagnosis, most children do not exhibit any significant worsening of their condition and are routinely monitored using radiography as frequently as every three months whilst vertebral growth potential remains. In a small number of patients, the lateral curvature can unpredictably worsen requiring, in some cases, surgical intervention to prevent further deterioration and to diminish the deformity. Earlier work by many researchers concentrated on attempting to reduce patient exposure to ionizing radiation by investigating if there was a reliable correlation between progression of the scoliosis and changes in surface topography. The techniques have not gained acceptance as the relational algorithms were found to be insufficiently robust in all cases and measurements acquired from available technologies were prone to artefacts introduced by stance, breathing, 'posture and sway. For many patients the motivation in seeking treatment is for the improvement of their appearance rather than to correct the underlying deformity, so cosmetic concerns and an understanding of the psychosocial and physical impacts of the disease and treatments remain important factors in the clinical decision-making process. In the current environment of evidence based medicine there is a growing need to quantify back surface shape, general body asymmetry and patient capability with the objective of producing an agreed scoring to be used in developing treatment plans and assessing outcomes but to date many clinics continue to rely on qualitative methods to describe cosmetic deformity and ability. The aim of the research was to develop an original, low cost and inherently safe apparatus using well understood video based motion capture technology that overcame the disadvantages of earlier work by simultaneously acquiring multiple samples of back surface shape and the locations of bony landmarks to provide averaged results for a quantitative and reliable analysis of cosmetic defect and physical impairment. 172,650 data samples were acquired from thirty skeletally mature subjects not exhibiting any musculoskeletal disease to define normality limits for Page 2 established morphological measurements and to compare the specificity of the approach with existing single sample techniques. Three novel calculations of back paraspinous volumetric asymmetry were tested of which two were found to be potentially useful clinical indicators of deformity and an index was proposed and tested using simulated data that could offer a single value to describe patient back shape asymmetry. Previous research has found that there is a loss of trunk ranges of motion among postoperative patients that has a direct impact on their quality of life, function and physical capability. Data were acquired from the mature subjects and similar results were observed when compared with published data for preoperative scoliosis patients. This thesis has shown that using averaged tri-dimensional morphological and back shape data combined with measurement of dynamic capability acquired using an inherently safe apparatus have the potential to be clinically useful. The opportunity to routinely and safely quantify the cosmetic defect and trunk ranges of motion of adolescent idiopathic scoliosis patients should stimulate more important research to help improve the quality of life of many affected children throughout the world

Utilization of Finite Element Analysis Techniques for Adolescent Idiopathic Scoliosis Surgical Planning

Adolescent Idiopathic Scoliosis, a three-dimensional deformity of the thoracolumbar spine, affects approximately 1-3% of patients ages 10-18. Surgical correction and treatment of the spinal column is a costly and high-risk task that is consistently complicated by factors such as patient-specific spinal deformities, curve flexibility, and surgeon experience. The following dissertation utilizes finite element analysis to develop a cost-effective, building-block approach by which surgical procedures and kinematic evaluations may be investigated. All studies conducted are based off a volumetric, thoracolumbar finite element (FE) model developed from computer-aided design (CAD) anatomy whose components are kinematically validated with in-vitro data. Spinal ligament stiffness properties derived from the literature are compared for kinematic assessment of a thoracic functional spinal unit (FSU) and benchmarked with available in-vitro kinematic data. Once ligament stiffness properties were selected, load sharing among soft tissues (e.g., ligaments and intervertebral disc) within the same FSU is then assessed during individual steps of a posterior correction procedure commonly used on scoliosis patients. Finally, the entire thoracolumbar spine is utilized to mechanically induce a mild scoliosis profile through an iterative preload and growth procedure described by the Hueter-Volkmann law. The mild scoliosis model is then kinematically compared with an asymptomatic counterpart. The thoracic deformation exhibited in the mild scoliosis model compared well with available CT datasets. Key findings of the studies confirm the importance of appropriately assigning spinal ligament properties with traditional toe and linear stiffness regimes to properly characterize thoracic spine FE models. Stiffness properties assigned within spinal FE models may also alter how intact ligaments and intervertebral discs respond to external loads during posterior correction procedures involving serial ligament removal, and thus can affect any desired post-surgical outcomes. Lastly, the thoracolumbar spine containing mild scoliosis experiences up to a 37% reduction in global range of motion compared to an asymptomatic spine, while also exhibiting larger decreases in segmental axial rotations at apical deformity levels. Future studies will address kinematic behavior of a severe scoliosis deformity and set the stage for column-based osseoligamentous load sharing assessments during surgical procedures

Experimental validation of a patient-specific model of orthotic action in adolescent idiopathic scoliosis

This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.PURPOSE: Personalized modeling of brace action has potential in improving brace efficacy in adolescent idiopathic scoliosis (AIS). Model validation and simulation uncertainty are rarely addressed, limiting the clinical implementation of personalized models. We hypothesized that a thorough validation of a personalized finite element model (FEM) of brace action would highlight potential means of improving the model. METHODS: Forty-two AIS patients were included retrospectively and prospectively. Personalized FEMs of pelvis, spine and ribcage were built from stereoradiographies. Brace action was simulated through soft cylindrical pads acting on the ribcage and through displacements applied to key vertebrae. Simulation root mean squared errors (RMSEs) were calculated by comparison with the actual brace action (quantified through clinical indices, vertebral positions and orientations) observed in in-brace stereoradiographies. RESULTS: Simulation RMSEs of Cobb angle and vertebral apical axial rotation was lower than measurement uncertainty in 79 % of the patients. Pooling all patients and clinical indices, 87 % of the indices had lower RMSEs than the measurement uncertainty. CONCLUSIONS: In-depth analysis suggests that personalization of spinal functional units mechanical properties could improve the simulation's accuracy, but the model gave good results, thus justifying further research on its clinical application