An Image-Based Tool to Examine Joint Congruency at the Elbow

Post-traumatic osteoarthritis commonly occurs as a result of a traumatic event to the articulation. Although the majority of this type of arthritis is preventable, the sequence and mechanism of the interaction between joint injury and the development of osteoarthritis (OA) is not well understood. It is hypothesized that alterations to the joint alignment can cause excessive and damaging wear to the cartilage surfaces resulting in OA. The lack of understanding of both the cause and progression of OA has contributed to the slow development of interventions which can modify the course of the disease. Currently, there have been no reported techniques that have been developed to examine the relationship between joint injury and joint alignment. Therefore, the objective of this thesis was to develop a non-invasive image-based technique that can be used to assess joint congruency and alignment of joints undergoing physiologic motion. An inter-bone distance algorithm was developed and validated to measure joint congruency at the ulnohumeral joint of the elbow. Subsequently, a registration algorithm was created and its accuracy was assessed. This registration algorithm registered 3D reconstructed bone models obtained using x-ray CT to motion capture data of cadaveric upper extremities undergoing simulated elbow flexion. In this way, the relative position and orientation of the 3D bone models could be visualized for any frame of motion. The effect of radial head arthroplasty was used to illustrate the utility of this technique. Once this registration was refined, the inter-bone distance algorithm was integrated to be able to visualize the joint congruency of the ulnohumeral joint undergoing simulated elbow flexion. The effect of collateral ligament repair was examined. This technique proved to be sensitive enough to detect large changes in joint congruency in spite of only small changes in the motion pathways of the ulnohumeral joint following simulated ligament repair. Efforts were also made in this thesis to translate this research into a clinical environment by examining CT scanning protocols that could reduce the amount of radiation exposure required to image patient’s joints. For this study, the glenohumeral joint of the shoulder was examined as this joint is particularly sensitive to potential harmful effects of radiation due to its proximity to highly radiosensitive organs. Using the CT scanning techniques examined in this thesis, the effective dose applied to the shoulder was reduced by almost 90% compared to standard clinical CT imaging. In summary, these studies introduced a technique that can be used to non-invasively and three-dimensionally examine joint congruency. The accuracy of this technique was assessed and its ability to predict regions of joint surface interactions was validated against a gold standard casting approach. Using the techniques developed in this thesis the complex relationship between injury, loading and mal-alignment as contributors to the development and progression of osteoarthritis in the upper extremity can be examined

Subchondral bone density distribution of the talus in clinically normal Labrador Retrievers

Background: Bones continually adapt their morphology to their load bearing function. At the level of the subchondral bone, the density distribution is highly correlated with the loading distribution of the joint. Therefore, subchondral bone density distribution can be used to study joint biomechanics non-invasively. In addition physiological and pathological joint loading is an important aspect of orthopaedic disease, and research focusing on joint biomechanics will benefit veterinary orthopaedics. This study was conducted to evaluate density distribution in the subchondral bone of the canine talus, as a parameter reflecting the long-term joint loading in the tarsocrural joint. Results: Two main density maxima were found, one proximally on the medial trochlear ridge and one distally on the lateral trochlear ridge. All joints showed very similar density distribution patterns and no significant differences were found in the localisation of the density maxima between left and right limbs and between dogs. Conclusions: Based on the density distribution the lateral trochlear ridge is most likely subjected to highest loads within the tarsocrural joint. The joint loading distribution is very similar between dogs of the same breed. In addition, the joint loading distribution supports previous suggestions of the important role of biomechanics in the development of OC lesions in the tarsus. Important benefits of computed tomographic osteoabsorptiometry (CTOAM), i.e. the possibility of in vivo imaging and temporal evaluation, make this technique a valuable addition to the field of veterinary orthopaedic research

Freehand Three-Dimensional Ultrasound to Evaluate Scapular Movement

Altered scapular kinematics have been linked to increases in shoulder pain and pathology. As such, identifying normal scapular movement is integral to preventing pathology and maintaining health of the joint. Existing methods to evaluate scapular movement are invasive, expensive, require exposure to radiation, suffer skin based motion artifacts, or allow for examination only in static postures. Freehand three-dimensional ultrasound offers the unique ability to image bone while being non-invasive, relatively low cost, and free of radiation. This is a novel application of a technology that in the past has been used for needle guided injections and determining changes in organ volumes, but never for evaluating bone movement. We have developed a custom freehand-ultrasound system that shows high repeatability across trials (SEM < 2°) in evaluating scapular kinematics in static postures with the arm at rest and elevated in the sagittal, frontal and scapular planes. Among manual wheelchair users and able-bodied controls we found scapular kinematics with the arm in an elevated position were predicted by scapular and trunk position at rest. We also found BMI ≥ 25, presence of pathology on a physical exam, shoulder abnormalities on a clinical ultrasound exam, and greater than 10 years of wheelchair use resulted in scapular postures associated with shoulder pathology in previous studies. We found no significant differences between wheelchair users and age-matched controls but attribute this to a lack of difference in pathology between the groups. A learning curve was identified over time for capturing quality ultrasound images and it is suggested future studies incorporate ample training time and require raters to meet minimum performance measures set forth by this study. In a subsample of subjects we found increases in external rotation, upward rotation and posterior tilting at incremental angles of humeral elevation during dynamic trials indicating that it is feasible to apply our methods to evaluate dynamic scapular movement. Application of these methods may help to identify shoulder pathology and evaluate the efficacy of interventions to correct altered scapular kinematics

Statistical Shape and Intensity Modeling of the Shoulder

Anatomical variability in the shoulder is inherently present and can influence healthy and pathologic biomechanics and ultimately clinical decision-making. Characterizing variation in bony morphology and material properties in the population can support treatment and specifically the design, via shape and sizing, of shoulder implants. Total Shoulder Arthroplasty (TSA) is the treatment of choice for glenohumeral osteoarthritis as well as bone fracture. Complications and poor outcomes in TSA are generally influenced by the inability of the implant to replicate the natural joint biomechanics and by the bone quality around the fixation features. For this reason, knowledge of bony morphology and mechanical properties can support optimal implant design and sizing, and thus improve TSA results. Statistical shape and intensity modeling is a powerful tool to represent the shape and mechanical properties variation in a training set. Accordingly, the objectives of this thesis were: 1) to develop a statistical shape model (SSM) of the proximal humeral cortical and cancellous bone; 2) to develop an SSM and a statistical intensity model (SIM) of the scapular bone. A training set of 85 humeri and 53 scapulae were reconstructed from CT scans and registered to common templates. Principal Component Analysis (PCA) was applied to the registered geometries to quantify morphological and bone properties variation in the population. For both the humerus and the scapula SSM, the first mode of variation accounted for most of the variation and described scaling. Subsequent modes described changes in the scapular plate, acromion process and scapular notch for the scapula, and in the neck angle, head inclination, greater and lesser tubercles for the humerus. Variation in cortical thickness of the humeral diaphysis was largely independent of size and statistically significant differences with ethnicity were noted. Asian subjects showed higher humeral cortical thickness with respect to Caucasians, regardless of gender. The first mode of variation in the scapular SIM described scaling in material properties distribution, with higher bone density located centrally and anteriorly in the glenoid region. The bone property maps developed for the scapular training set realistically captured inter-subject variability and they represent a valuable tool to assess fixation features and screw location and trajectories for TSA glenoid component. The SSMs and SIM developed in this thesis represent a useful infrastructure to support population-based evaluations and assess possible anatomical differences with gender and ethnicity, SSM and SIM can also provide anatomical relationship in support of implant design and sizing

The Use of CT to Assess Shoulder Kinematics and Measure Glenohumeral Arthrokinematics

Recently, studies have started employing dynamic four-dimensional computed tomography (4DCT) imaging as a biomechanical assessment tool. These studies would benefit from the valuable work that has been done in the past using three-dimensional computed tomography (3DCT). Thus, a structured review was conducted to examine the extent and range of methods employing CT imaging to measure shoulder kinematics. The findings of the review were utilized to conduct a study that employed 4DCT imaging to measure glenohumeral joint congruency and arthrokinematics during internal rotation to the back in a population of healthy individuals. The results of this work show the importance of anterior-posterior translation throughout the motion to achieve maximum range of motion. In conclusion, the use of 4DCT as a biomechanical measuring tool has shown to be a reliable technique in quantifying joint congruency and arthrokinematics of the glenohumeral joint and shows promise for future studies

Virtual interactive musculoskeletal system (VIMS) in orthopaedic research, education and clinical patient care

The ability to combine physiology and engineering analyses with computer sciences has opened the door to the possibility of creating the "Virtual Human" reality. This paper presents a broad foundation for a full-featured biomechanical simulator for the human musculoskeletal system physiology. This simulation technology unites the expertise in biomechanical analysis and graphic modeling to investigate joint and connective tissue mechanics at the structural level and to visualize the results in both static and animated forms together with the model. Adaptable anatomical models including prosthetic implants and fracture fixation devices and a robust computational infrastructure for static, kinematic, kinetic, and stress analyses under varying boundary and loading conditions are incorporated on a common platform, the VIMS (Virtual Interactive Musculoskeletal System). Within this software system, a manageable database containing long bone dimensions, connective tissue material properties and a library of skeletal joint system functional activities and loading conditions are also available and they can easily be modified, updated and expanded. Application software is also available to allow end-users to perform biomechanical analyses interactively. Examples using these models and the computational algorithms in a virtual laboratory environment are used to demonstrate the utility of these unique database and simulation technology. This integrated system, model library and database will impact on orthopaedic education, basic research, device development and application, and clinical patient care related to musculoskeletal joint system reconstruction, trauma management, and rehabilitation

Computer-assisted planning vs. conventional surgery for the correction of symptomatic mid-shaft clavicular nonunion and malunion

BACKGROUND The aim of this study was to compare the clinical and radiographic outcomes of treatment of symptomatic mal- and/or nonunion of midshaft clavicle fractures using radiographically based free-hand open reduction and internal fixation (ORIF) or computer-assisted 3D-planned, personalized corrective osteotomies performed using patient-specific instrumentation (PSI) and ORIF. The hypotheses were that (1) patients treated with computer-assisted planning and PSI would have a better clinical outcome, and (2) computer-assisted surgical planning would achieve a more accurate restoration of anatomy compared to the free-hand technique. METHODS Between 1998 and 2020, 13 patients underwent PSI, and 34 patients underwent free-hand ORIF and/or corrective osteotomy. After application of exclusion criteria, 12/13 and 11/34 patients were included in the study. The clinical examination included measurement of the active range of motion and assessment of the absolute and relative Constant-Murley Scores and the subjective shoulder value. Subjective satisfaction with the cosmetic result was assessed on a Likert scale from 0 to 100 (subjective aesthetic value). 11/13 and 6/11 patients underwent postoperative computed tomography evaluation of both clavicles. Computed tomography scans were segmented to generate 3D surface models. After projection onto the mirrored contralateral side, displacement analysis was performed. Finally, bony union was documented. The average follow-up time was 43 months in the PSI and 50 months in the free-hand cohort. RESULTS The clinical outcomes of both groups did not differ significantly. Median subjective shoulder value was 97.5% (70; 100) in the PSI group vs. 90% (0; 100) in the free-hand group; subjective aesthetic value was 86.4% (±10.7) vs. 75% (±18.7); aCS was 82.3 (±10.3) points vs. 74.9 (±26) points; and rCS was 86.7 (±11.3) points vs. 81.9 (±28.1) points. In the free-hand group, 2/11 patients had a postoperative neurological complication. In the PSI cohort, the 3D angle deviation was significantly smaller (PSI/planned vs. free-hand/contralateral: 10.8° (3.1; 23.8) vs. 17.4° (11.6; 42.4); P = .020)). There was also a trend toward a smaller 3D shift, which was not statistically significant (PSI/planned vs. free-hand/contralateral: 6 mm (3.4; 18.3) vs. 9.3 mm (5.1; 18.1); P = .342). There were no other significant differences. A bony union was achieved in all cases. CONCLUSION Surgical treatment of nonunion and malunions of the clavicle was associated with very good clinical results and a 100% union rate. This study, albeit in a relatively small cohort with a follow-up of 4 years, could not document any clinically relevant advantage of 3D planning and personalized operative templating over conventional radiographic planning and free-hand surgical fixation performed by experienced surgeons

DESIGN, VALIDATION AND NAVIGATION OF ANATOMIC POPULATION- BASED AND PATIENT-SPECIFIC RADIAL HEAD IMPLANTS

Radial head replacement for fractures and arthritis are commonly performed; however, most available implants do not accurately replicate the complex native anatomy. This work examines the creation and surgical implantation of an anatomic implant system. Radial head morphology was parameterized using ellipse fitting to allow reverse engineering of the shape (n=50). Using the derived parameters, anatomic implants were generated for both a population “average” and patient-specific designs. Mean surface mismatch between these implant models and the native morphology was compared to an existing axisymmetric implant (n=34). Anatomic designs showed reduced mismatch relative to the existing implant with the anatomic patient-specific design performing best. A surgical navigation system was developed and tested for implant alignment. The mean placement accuracy and standard deviation was 1.5±0.5mm in translation and 1.2±1.0°, 1.4±1.8°and 5.5±3.2° in rotation about the lateral, anterior and proximal axes respectively (n=7). These studies demonstrate the feasibility of anatomic radial head implant designs; however, further work is required to improve placement accuracy

Distal Humerus Hemiarthroplasty: Joint Kinematics, Stability, Congruency and Implant Design

Distal humeral hemiarthroplasty is a treatment option for fractures, non-unions and avascular necrosis of the distal humerus. Commercially available distal humeral implants are available; however, many unanswered questions remain regarding their role in treatment of distal humeral pathology. The optimal articular shape of the implant has not been defined, the biomechanical effects have not been reported, and contact stresses on native articular cartilage are unknown. This work has defined the osseous anatomy and anatomic variability of the distal humeral articulation using accurate 3D reconstruction methods. A data bank of distal humeral dimensions has been created and may be effective in the development of future implants. Kinematic investigations have shown small but significant alteration in elbow joint kinematics with placement of a distal humeral hemiarthroplasty. This work shows that currently available hemiarthroplasty implants may not be anatomically accurate, and may not reproduce native elbow kinematics. Further efforts are needed to create and test more anatomic distal humeral implants

Foot and ankle functional morphology in anthropoid primates and Miocene hominoids

Locomotion is essential for survival in many taxa. It also varies greatly among organisms, including primates. Studying locomotor diversity in extant and fossil primates requires an understanding of form-function relationships. This is particularly true in the foot and ankle, as the foot directly contacts the substrate and tarsals are well-represented in the fossil record. Morphological differences alone provide limited aid when inferring locomotion from fossil tarsals in the absence of in vivo biomechanical consideration. This dissertation takes a three-step approach to analyze both in vivo rotations in the foot and ankle as well as morphological variation in tarsal form in extant anthropoid primates and Miocene hominoids and will provide important new data from a poorly understood anatomical region. The amount of talocrural, subtalar, and transverse tarsal rotations among the tibia, calcaneus, and navicular were visualized and quantified during the gait cycles using biplanar fluoroscopy and 3D scans of marked bones, a method known as x-ray reconstruction of moving morphology (XROMM) in rhesus macaques (Macaca mulatta). This study supported previous hypotheses that the midfoot break occurs distal to the cuboid, demonstrated the predominance of plantarflexion/dorsiflexion at the talocrural joint on a flat surface, quantified conjunct rotation at the subtalar joint, showed evidence that the transverse tarsal joint does not function as a single joint complex. Geometric morphometric techniques were used to describe and quantify shape differences in isolated tarsals of extant anthropoid primates. PCA and M/ANOVA analyses were run on a Procrustes-fit landmarks taken on broad range of anthropoid tali (n = 241), calcanei (n = 230), cuboids (n = 282), and naviculars (n = 254). In addition to the typical geometric morphometric techniques, the interlandmark distances that accounted for the greatest amount of variation in this sample were isolated and plotted against centroid size. Phylogenetically controlled generalized least squares analysis revealed which of these measurements were related to locomotion. The relative orientation of the posterior subtalar facet on the talus, talar neck length, calcaneal tuber height, calcaneal anterior length, cuboid length, and navicular anteroposterior length were the morphologies that best separated based on differences in locomotion. The same landmarks were taken on 16 Miocene hominoid tarsals in order to infer foot function based on tarsal form. The geometric morphometric technique of the extant sample allowed for subsetted analyses for incomplete fossils. Early Miocene taxa Ekembo, Proconsul, and Rangwapithecus shared common bony features that suggest that they were generally above branch quadrupeds. Nacholapithecus showed a mixed or varied locomotor behavior. Oreopithecus was shown to not be bipedal, as previously hypothesized, but rather was suspensory. This dissertation provided the first ever quantification of intertarsal and talocrural rotations in anthropoid primate feet and ankles and an analysis of how rotations within and among joints are related. It also provided a quantification of shape differences in tarsals of extant anthropoid primates and fossil Miocene hominoids. Together, the in vivo biomechanics and morphometrics provide insight into form function relationships as well as a foundation for future studies of primate locomotor diversity