Assessment of Normal Knee Kinematics Using High-Speed Stereo-Radiography System

The measurement of dynamic joint kinematics in vivo is important in order to understand the effects of joint injuries and diseases as well as for evaluating the treatment effectiveness. Quantification of knee motion is essential for assessment of joint function for diagnosis of pathology, such as tracking and progression of osteoarthritis and evaluation of outcome following conservative or surgical treatment. Total knee arthroplasty (TKA) is an invasive treatment for arthritic pain and functional disability and it is used for deformed joint replacement with implants in order to restore joint alignment. It is important to describe knee kinematics in healthy individuals for comparison in diagnosis of pathology and understanding treatment to restore normal function. However measuring the in vivo dynamic biomechanics in 6 degrees of freedom with an accuracy that is acceptable has been shown to be technically challenging. Skin marker based methods, commonly used in human movement analysis, are still prone to large errors produced by soft tissue artifacts. Thus, great deal of research has been done to obtain more accurate data of the knee joint by using other measuring techniques like dual plane fluoroscopy. The goal of this thesis is to use high-speed stereo radiography (HSSR) system for measuring joint kinematics in healthy older adults performing common movements of daily living such as straight walking and during higher demand activities of pivoting and step descending in order to establish a useful baseline for the envelope of healthy knee motion for subsequent comparison with patients with TKA. Prior to data collection, validation and calibration techniques as well as dose estimations were mandatory for the successful accomplishment of this study

Orthopedic management of the extremities in patients with Morquio A syndrome.

BackgroundMusculoskeletal involvement in Morquio A syndrome (mucopolysaccharidosis IVA; MPS IVA) contributes significantly to morbidity and mortality. While the spinal manifestations of the disorder have received considerable attention in the literature, there have been few reported studies to date to guide the management of the orthopedic problems associated with the lower and upper extremities.PurposeThe objective was to develop recommendations for the management of the extremities in patients with Morquio A syndrome.MethodsA group of specialists in orthopedics, pediatrics and genetics with experience in the management of Morquio A patients convened to review and discuss current clinical practices and to develop preliminary recommendations. Evidence from the literature was retrieved. Recommendations were further refined until consensus was reached.Results and conclusionsThis present article provides a detailed review and discussion of the lower and upper extremity deformities in Morquio A syndrome and presents recommendations for the assessment and treatment of these complications. Key issues, including the importance of early diagnosis and the implications of medical therapy, are also addressed. The recommendations herein represent an attempt to develop a uniform and practical approach to managing patients with Morquio A syndrome and improving their outcomes

Biomechanical Investigations of Medial Opening Wedge High Tibial Osteotomy: Gait Analysis, Materials Testing and Dynamic Radiography

This thesis aimed to develop and assess biomechanical methods to assist in the evaluation of medial opening wedge high tibial osteotomy (HTO). Five studies using diverse methods were performed, including three-dimensional (3D) gait analysis, materials testing of HTO fixation plates, and dynamic radiography in patients after surgery. Study 1 compared external knee joint moments during walking before and after varus or valgus producing osteotomy in patients with lateral or medial compartment osteoarthritis, and in healthy participants. The results highlighted the importance of alignment on gait biomechanics with changes in frontal plane angular impulse highly correlated to changes in mechanical axis. Study 2 compared the 3D external knee moments before and after medial opening wedge HTO during level walking and during stair ascent. Long-term changes in knee moments after HTO were observed during both activities, with decreases in the peak knee adduction and internal rotation moments. Study 3 developed and tested a multi-axis fixation jig placed within a materials testing machine for assessing HTO fixation plates in a manner more representative of walking. The need to incorporate gait data into materials testing studies was highlighted, showing the importance of including a frontal plane moment during testing. Study 4 used this multi-axis fixation jig to compare flat to toothed HTO fixation plates under cyclic loading conditions. Preliminary results suggested little difference in the load at failure between the plates; however, the potential for the tooth to increase micro-motion across the osteotomy site and strain on the lateral cortical hinge should be a focus of future testing. Study 5 was a proof-of-concept study to test dynamic single-plane flat-panel (FP) radiography for use in detecting in-vivo micro-motion after medial opening wedge HTO. Preliminary results suggested dynamic FP radiography has the potential to assess fixation stability; however, results also suggested modifications in the registration algorithms may be required to increase confidence in distinguishing true motion from registration error. Overall, this thesis demonstrates that a mix of biomechanical methods can be used to advance medial opening wedge HTO, with particular focus on informing future methods of investigation to improve HTO fixation designs

Quantitative Analysis of Three-Dimensional Cone-Beam Computed Tomography Using Image Quality Phantoms

In the clinical setting, weight-bearing static 2D radiographic imaging and supine 3D radiographic imaging modalities are used to evaluate radiographic changes such as, joint space narrowing, subchondral sclerosis, and osteophyte formation. These respective imaging modalities cannot distinguish between tissues with similar densities (2D imaging), and do not accurately represent functional joint loading (supine 3D imaging). Recent advances in cone-beam CT (CBCT) have allowed for scanner designs that can obtain weight-bearing 3D volumetric scans. The purpose of this thesis was to analyze, design, and implement advanced imaging techniques to quantify image quality parameters of reconstructed image volumes generated by a commercially-available CBCT scanner, and a novel ceiling-mounted CBCT scanner. In addition, imperfections during rotation of the novel ceiling-mounted CBCT scanner were characterized using a 3D printed calibration object with a modification to the single marker bead method, and prospective geometric calibration matrices

Kinect-Based Correction of Overexposure Artifacts in Knee Imaging with C-Arm CT Systems

Objective. To demonstrate a novel approach of compensating overexposure artifacts in CT scans of the knees without attaching any supporting appliances to the patient. C-Arm CT systems offer the opportunity to perform weight-bearing knee scans on standing patients to diagnose diseases like osteoarthritis. However, one serious issue is overexposure of the detector in regions close to the patella, which can not be tackled with common techniques. Methods. A Kinect camera is used to algorithmically remove overexposure artifacts close to the knee surface. Overexposed near-surface knee regions are corrected by extrapolating the absorption values from more reliable projection data. To achieve this, we develop a cross-calibration procedure to transform surface points from the Kinect to CT voxel coordinates. Results. Artifacts at both knee phantoms are reduced significantly in the reconstructed data and a major part of the truncated regions is restored. Conclusion. The results emphasize the feasibility of the proposed approach. The accuracy of the cross-calibration procedure can be increased to further improve correction results. Significance. The correction method can be extended to a multi-Kinect setup for use in real-world scenarios. Using depth cameras does not require prior scans and offers the possibility of a temporally synchronized correction of overexposure artifacts. To achieve this, we develop a cross-calibration procedure to transform surface points from the Kinect to CT voxel coordinates

Custom-Made Devices Represent a Promising Tool to Increase Correction Accuracy of High Tibial Osteotomy: A Systematic Review of the Literature and Presentation of Pilot Cases with a New 3D-Printed System

Background: The accuracy of the coronal alignment corrections using conventional high tibial osteotomy (HTO) falls short, and multiplanar deformities of the tibia require consideration of both the coronal and sagittal planes. Patient-specific instrumentations have been introduced to improve the control of the correction. Clear evidence about customized devices for HTO and their correction accuracy lacks. Methods: The databases PUBMED and EMBASE were systematically screened for human and cadaveric studies about the use of customized devices for high tibial osteotomy and their outcomes concerning correction accuracy. Furthermore, a 3D-printed customized system for valgus HTO with three pilot cases at one-year follow-up was presented. Results: 28 studies were included. The most commonly used custom-made devices for HTO were found to be cutting guides. Reported differences between the achieved and targeted correction of hip-knee-ankle angle and the posterior tibial slope were 3 degrees or under. The three pilot cases that underwent personalized HTO with a new 3D-printed device presented satisfactory alignment and clinical outcomes at one-year follow-up. Conclusion: The available patient-specific devices described in the literature, including the one used in the preliminary cases of the current study, showed promising results in increasing the accuracy of correction in HTO procedure

Robotic arm-assisted bi-unicompartmental knee arthroplasty maintains natural knee joint anatomy compared with total knee arthroplasty : a prospective randomized controlled trial

Aims The aim of this study was to compare robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) in order to determine the changes in the anatomy of the knee and alignment of the lower limb following surgery. Methods An analysis of 38 patients who underwent TKA and 32 who underwent bi-UKA was performed as a secondary study from a prospective, single-centre, randomized controlled trial. CT imaging was used to measure coronal, sagittal, and axial alignment of the knee preoperatively and at three months postoperatively to determine changes in anatomy that had occurred as a result of the surgery. The hip-knee-ankle angle (HKAA) was also measured to identify any differences between the two groups. Results The pre- to postoperative changes in joint anatomy were significantly less in patients undergoing bi-UKA in all three planes in both the femur and tibia, except for femoral sagittal component orientation in which there was no difference. Overall, for the six parameters of alignment (three femoral and three tibial), 47% of bi-UKAs and 24% TKAs had a change of < 2° (p = 0.045). The change in HKAA towards neutral in varus and valgus knees was significantly less in patients undergoing bi-UKA compared with those undergoing TKA (p < 0.001). Alignment was neutral in those undergoing TKA (mean 179.5° (SD 3.2°)) while those undergoing bi-UKA had mild residual varus or valgus alignment (mean 177.8° (SD 3.4°)) (p < 0.001). Conclusion Robotic-assisted, cruciate-sparing bi-UKA maintains the natural anatomy of the knee in the coronal, sagittal, and axial planes better, and may therefore preserve normal joint kinematics, compared with a mechanically aligned TKA. This includes preservation of coronal joint line obliquity. HKAA alignment was corrected towards neutral significantly less in patients undergoing bi-UKA, which may represent restoration of the pre-disease constitutional alignment (p < 0.001)

Biomechanical effects of patellar taping in subjects with patellofemoral pain syndrome (PFPS).

PhDPatellofemoral pain syndrome (PFPS) is one of the most common musculoskeletal disorders affecting adults. Patellar taping provides an effective treatment in alleviating the symptoms of a high proportion of subjects who present with PFPS. However, the mechanisms of pain reduction have not been established. The aim of this work was to evaluate the effects of patellar taping on the biomechanics of the patellofemoral joint and level of pain in PFPS subjects, during the eccentric phase of single leg squatting at 30° of knee flexion. These were determined with a combined kinetic and kinematic approach using data from video analysis, force plate and EMG. A series of pilot tests was performed, involving a group of asymptomatic volunteers performing a number of knee flexion procedures. These tests demonstrated a high reliability in both the estimated patellofemoral joint reaction force (PFJRF) and relative amplitude of vasti, but less impressive reliability for the parameters associated with muscle onset. The main case-controlled study involved 18 PFPS subjects, recruited from a local Physiotherapy Department, and a similar number of healthy controls. The test procedure was performed on the knees of both subject groups and, where appropriate, during and after patellar taping. The results revealed that the mean value of PFJRF, which was 2025 N prior to taping, had decreased significantly to 1720 N (p< 0.05) following a period of taping and exercises which lasted between 2-5 weeks. Equivalent changes were also recorded with the pain levels, although the ratio of the amplitude of the vasti did not change during this period. The only significant differences between the two subject groups were with the relative timing of muscle onset, for which VMO preceded VL in the healthy controls. The reduction of biomechanical characteristics following the application of patellar tape and exercises in PFPS subjects, may explain the mechanism of pain reduction during the early phase of single leg squatting

Total Knee Arthroplasty Wear Is Caused by Malrotation and Excessive Laxity

Total knee arthroplasty is a proven technique which combines specially designed components and surgical processes to treat cartilage degeneration and alleviate pain in arthritic knees. However, this technique is limited by component design and surgical precision. Due to these limitations, knee arthroplasty components will eventually wear out, causing rejection and necessitating the need for a replacement. For this reason, it would be beneficial to experts if the primary causes of this wear could be identified in order to minimize the number of replacements. This study aims to determine if a correlation exists between instability of a knee joint and the amount of wear present in an implant, and also relate surgical alignment to this wear. To accomplish this aim, a custom laxity machine was used to assess joint stability in 20 knees of human bodies donated to science. This laxity data was compared to damage scores expressing the amount of wear on each implant specimen, and was used in conjuction with alignment data obtained from CT scans. Alignment data was expressed as the difference in component rotations, as well as a new method here named “congruency mismatch”. A significant correlation was found between wear and anterior and posterior laxity, indicating the need for additional constraint in implant design to minimize sliding which can lead to wear. No significant relationships were observed between either alignment analysis technique and wear scores. Results do show a positive postoperative relationship between external femoral rotation and increasing varus coronal angle, which is inversely related to previous studies which were undertaken preoperatively. Implant functionality and successful outcomes are directly related to design and proper surgical technique, which can be quantified and improved using new methods such as patient-specific design and robotic surgical system