Shape Modelling of Bones: Application to the Primate Shoulder

The aims of this work were to develop techniques for describing morphological variations of shoulder bones and to test these on real datasets. The robust measurement and description of anatomical geometry can provide accu- rate estimation and better understanding of bone morphology. Feature lines were detected automatically using crest line techniques and shape information from shoulder bones was extracted based on the extracted feature lines. Redefinition of local coordinate systems was proposed utilising the crest line technique. Three dimensional statistical shape models (SSM) were built for a set of primate humeri and scapulae. Two types of models were constructed: one incorporated the main- tained original scale whilst the other used scaled bones. Variations were captured and quantified by Principal Component Analysis (PCA). The application can be extended generally to long bones and other complex bones and was also tested on human femora. Techniques to predict the shape of one bone from its neighbour at a joint were presented. PCA was used to reduce data dimensionality to a few principal components. Canonical Correlation Analysis (CCA) and Partial Least Square (PLS) Regression were applied to explore the linear morphological correlations between the two shoulder bones and to predict the shape of one segment given the shape of the adjoining segment

Three-Dimensional Planning and Patient-Specific Instrumentation for the Fixation of Distal Radius Fractures

Background and Objectives: Three-dimensional planning and guided osteotomy utilizing patient-specific instrumentation (PSI) with the contralateral side used as a reference have been proven as effective in the treatment of malunions following complex fractures of the distal radius. However, this approach has not yet been described in relation to fracture reduction of the distal radius. The aim of this study was to assess the technical and logistical feasibility of computer-assisted surgery in a clinical setting using PSI for fracture reduction and fixation. Materials and Methods: Five patients with varied fracture patterns of the distal radius underwent operative treatment with using PSI. The first applied PSI guide allowed specific and accurate placement of Kirschner wires inside the multiple fragments, with subsequent concurrent reduction using a second guide. Results: Planning, printing of the guides, and operations were performed within 5.6 days on average (range of 1-10 days). All patients could be treated within a reasonable period of time, demonstrating good outcomes, and were able to return to work after a follow-up of three months. Mean wrist movements (°) were 58 (standard deviation (SD) 21) in flexion, 62 (SD 15) in extension, 73 (SD 4) in pronation and 74 (SD 10) in supination at a minimum follow-up of 6 months. Conclusions: Three-dimensional planned osteosynthesis using PSI for treatment of distal radius fractures is feasible and facilitates reduction of multiple fracture fragments. However, higher costs must be taken into consideration for this treatment

Three-Dimensional Planning and Patient-Specific Instrumentation for the Fixation of Distal Radius Fractures

Background and Objectives: Three-dimensional planning and guided osteotomy utilizing patient-specific instrumentation (PSI) with the contralateral side used as a reference have been proven as effective in the treatment of malunions following complex fractures of the distal radius. However, this approach has not yet been described in relation to fracture reduction of the distal radius. The aim of this study was to assess the technical and logistical feasibility of computer-assisted surgery in a clinical setting using PSI for fracture reduction and fixation. Materials and Methods: Five patients with varied fracture patterns of the distal radius underwent operative treatment with using PSI. The first applied PSI guide allowed specific and accurate placement of Kirschner wires inside the multiple fragments, with subsequent concurrent reduction using a second guide. Results: Planning, printing of the guides, and operations were performed within 5.6 days on average (range of 1–10 days). All patients could be treated within a reasonable period of time, demonstrating good outcomes, and were able to return to work after a follow-up of three months. Mean wrist movements (°) were 58 (standard deviation (SD) 21) in flexion, 62 (SD 15) in extension, 73 (SD 4) in pronation and 74 (SD 10) in supination at a minimum follow-up of 6 months. Conclusions: Three-dimensional planned osteosynthesis using PSI for treatment of distal radius fractures is feasible and facilitates reduction of multiple fracture fragments. However, higher costs must be taken into consideration for this treatment

Development of an In-Vitro Passive and Active Motion Simulator for the Investigation of Shoulder Function and Kinematics

Injuries and degenerative diseases of the shoulder are common and may relate to the joint’s complex biomechanics, which rely primarily on soft tissues to achieve stability. Despite the prevalence of these disorders, there is little information about their effects on the biomechanics of the shoulder, and a lack of evidence with which to guide clinical practice. Insight into these disorders and their treatments can be gained through in-vitro biomechanical experiments where the achieved physiologic accuracy and repeatability directly influence their efficacy and impact. This work’s rationale was that developing a simulator with greater physiologic accuracy and testing capabilities would improve the quantification of biomechanical parameters. This dissertation describes the development and validation of a simulator capable of performing passive assessments, which use experimenter manipulation, and active assessments – produced through muscle loading. Respectively, these allow the assessment of functional parameters such as stability, and kinematic/kinetic parameters including joint loading. The passive functionality enables specimen motion to be precisely controlled through independent manipulation of each rotational degree of freedom (DOF). Compared to unassisted manipulation, the system improved accuracy and repeatability of positioning the specimen (by 205% & 163%, respectively), decreased variation in DOF that are to remain constant (by 6.8°), and improved achievement of predefined endpoints (by 21%). Additionally, implementing a scapular rotation mechanism improved the physiologic accuracy of simulation. This enabled the clarification of the effect of secondary musculature on shoulder function, and the comparison of two competing clinical reconstructive procedures for shoulder instability. This was the first shoulder system to use real time kinematic feedback and PID control to produce active motion, which achieved unmatched accuracy ( These developments can be a powerful tool for increasing our understanding of the shoulder and also to provide information which can assist surgeons and improve patient outcomes

The effect of implant misalignment on shoulder replacement outcomes

Total shoulder arthroplasty is a well-established treatment to relieve pain and restore joint function particularly in arthritis patients. The damaged shoulder joint is replaced with humeral and glenoid components. For success, all replacement components must be aligned properly. However, errors in glenoid component alignment particularly in version is not infrequent due to the complexities such as limited monitoring available during the surgical procedure and glenoid posterior wear, commonly observed in glenohumeral osteoarthritis. Glenoid component version has been found to induce eccentric load and may result in component loosening which is the main indicator for revision surgery. The overall aim of this thesis is to gain the in-depth understanding of how the component version affects the fixation loosening in both cementless and cemented shoulder arthroplasty. Early loosening in cementless arthroplasty is associated with failed biological fixation due to excessive micromotion at the implant-bone interface. To measure interface micromotion, this thesis developed an in-vitro technique based on the application of digital volume correlation (DVC) and micro-computed tomography (μCT). This technique was validated and verified the use of the finite element (FE) method as a tool for investigating the effect of glenoid component version on micromotion. The FE predicted micromotion during a full range of shoulder abduction confirmed that 60° of abduction was the critical position inducting the largest micromotion and large micromotions were shown to be related to increased component retroversion. The condition of the bone was also found to be an important parameter as less stiff bone caused large micromotions.Open Acces

Multiscale Geometric Methods for Isolating Exercise Induced Morphological Adaptations in the Proximal Femur

The importance of skeletal bone in the functioning of the human body is well-established and acknowledged. Less pervasive among the populace, is the understanding of bone as an adaptive tissue which modulates itself to achieve the most construction sufficient for the role it is habituated to. These mechanisms are more pronounced in the long load bearing bones such as the femur. The proximal femur especially, functions under significant loads and does so with high degree of articulation, making it critical to mobility. Thus, exercising to buttress health and reinforce tissue quality is just as applicable to bone as it is to muscles. However, the efficiency of the adaptive (modelling/remodelling) processes is subdued after maturity, which makes the understanding of its potential even more important. Classically, studies have translated the evaluation of strength in terms of its material and morphology. While the morphology of the femur is constrained within a particular phenotype, minor variations can have a significant bearing on its capability to withstand loads. Morphology has been studied at different scales and dimensions wherein parameters quantified as lengths, areas, volumes and curvatures in two and three dimensions contribute towards characterising strength. The challenge has been to isolate the regions that show response to habitual loads. This thesis seeks to build on the principles of computational anatomy and develop procedures to study the distribution of mechanically relevant parameters. Methods are presented that increase the spatial resolution of traditional cross-sectional studies and develop a conformal mapping procedure for proximal femur shape matching. In addition, prevalent methods in cross-sectional analyses and finite element simulations are employed to analyse the morphology of the unique dataset. The results present the spatial heterogeneity and a multi-scale understanding of the adaptive response in the proximal femur morphology to habitual exercise loading

Issues of Commingling Within the Gold Mine Site (16RI13) Collection: Adult Human Humeri and Tibiae

Gold Mine (16RI13) is a Troyville ossuary mound site (circa CE 825) in northeastern Louisiana. Approximately 10-20% of the primary mound (Mound A) was excavated over the course of three field seasons (1978-1980), yielding a host of human skeletal remains. Extensively commingled secondary burials make up the majority of interments. The number of individuals represented within the collection (N) has been estimated at 150+ (McGimsey 2004:214), but attempts to quantitatively determine N have produced varied results. Formal analysis of the skeletal collection is complicated by the loss of provenience for many remains as well as additional post-excavation fragmentation and commingling. Adult humeral and tibial material was selected for study and extensively documented, including observations on pathology and instances of animal modification, resulting in the production of the Gold Mine Site (16RI13) Adult Humerus and Tibia Photographic Catalog. In order to quantitatively determine N, visual pair-matching (VPM) was attempted for both humeri and tibiae; osteometric analysis could not be performed due to the lack of a comparable reference sample, but osteometric data were taken using a combination of the standard Forensic Database Measurements and supplementary measurements for fragmentary remains (Byrd and Adams 2003). The humerus VPM sample (MNI=53) proved inadequate for visual pair-matching due to the high degree of intra- and interobserver error. The less fragmentary and more morphologically distinct tibia VPM sample (MNI=38; author’s MLNI=65, r=48.48%, CI=50-88) produced more statistically-validated results. Pathologies were observed in over one third of all tibial elements, including multiple cases of anterior bowing (saber shin) possibly linked to treponemal infections. MNI and MLNI for the adult tibiae was lower than previously reported for adult femora (Lans 2011), suggesting differential treatment of the tibia at Gold Mine that restricted its representation within the recovered assemblage. Study of animal modification also yielded new insights into mortuary behaviors at Gold Mine; multiple cases of rodent gnawing consistent with gray squirrel gnawing patterns indicate that skeletal remains were left exposed to the elements for a minimum of 12-30 months prior to final interment within the mound

An Improved 2DOF Elastokinematic Surrogate Model for Continuous Motion Prediction and Visualisation of Forearm Pro-and Supination for Surgical Planning

Forearm rotation (pro-/supination) involves a non-trivial combination of rotation and translation of two bones, namely, radius and ulna, relatively to each other. Early works regarded this relative motion as a rotation about a fixed (skew) axis. However, this assumption turns out not to be exact. This thesis regards a spatial-loop surrogate mechanism involving two degrees of freedom with an elastic coupling for better forearm motion prediction. In addition, the influence of the bone morphology and position of elbow on kinematics are also considered. The model parameters are not measured directly from the anatomical components, but are fitted by reducing the errors between predicted and measured values in an optimization loop. For non-invasive measurement of bone position, magnetic resonance imaging (MRI) is employed. We present a method to self-calibrate the arm position in the MRI scanning tube and to fit the model parameters from a few, coarse MRI scans. Results show a good concordance between measurement and simulation. Moreover, the minimum distance changing between bones during forearm rotation is elucidated, which is not yet proved in anatomical and clinical literatures. The minimum distance is calculated by searching for the global shortest distance between bone contours on ulna and radius by a two-level selection and a following multidimensional Newton-Raphson algorithm. To this end, the methodology is extended from healthy bones to deformed arms and an angulated forearm model is developed. The 3D angulated bone geometry is obtained by manually separating the bone structure at the broken position, and the minimum distance and the range of motion of fractured forearms are analyzed. As shown for a single case validation, simulated results show very small deviations from anatomical data. Furthermore, the simulations discussed above are visualized using interactive interfaces, which facilitates the application of the model in clinical planning.Die Unterarmrotation beinhaltet eine nicht triviale Kombination einer Rotation und Translokation zweier Knochen, Radius und Ulna relativ zu einander. Frühere Arbeiten betrachteten diese relative Bewegung als eine Rotation um eine fixierte Achse. Allerdings scheint diese Annahme ungenau zu sein. Diese Arbeit betrachtet ein Spatial-Loop Surrogat Mechanismus unter Berücksichtigung von zwei Freiheitsgraden mit einer elastischen Gelenkverbindung für eine bessere Prognose der Unterarm-Bewegung. Zusätzlich wird der Einfluss der Knochenmorphologie und die Position des Ellenbogens auf die Kinematik berücksichtig. Die Modellparameter werden nicht direkt von den anatomischen Komponenten bestimmt, sondern unter Berücksichtigung der Abweichung von Annahme und Messung. Zur nicht invasiven Messung der Knochenposition wird die Methode der Magnetresonanztomographie (MRT) angewendet. Wir stellen hier eine Methode um die Arm-Position in das MRI Scan-Rohr selbst zu kalibrieren und die Modellparameter aus einige grobe MRT-Aufnahmen zu passen. Die simulierten Ergebnisse zeigen sehr kleine Abweichungen von anatomischen Daten. Eine minimale Änderung der Distanz zwischen den Knochen während der Unterarmrotation wird beleuchte, die bisher nicht in der anatomischen und klinischen Literatur beschrieben ist. Die Berechnung der minimalen Distanz erfolgt über die Ermittlung der gesamt kürzesten Distanz. Zu diesem Zweck wird die Methodik von gesunden Knochen auf deformiere Arme und ein angewinkeltes Unterarmmodel entwickelt. Die 3D gewinkelte Knochen-Geometrie ergibt sich aus der Knochenstruktur an der gebrochener Position manuell zu trennen, und darauf werden der Mindestabstand und der Bereich der Bewegung von dem gebrochenen Unterarm analysiert. Wie dies bei einer einzelnen Fall Validierung, zeigen die simulierten Ergebnisse sehr kleine Abweichungen von anatomischen Daten. Darüber hinaus werden die oben beschrieben Simulationen mit interaktiven Benutzeroberflächen visualisiert, welche die Anwendung des Modells in der klinischen Planung erleichtert