This thesis offers an overview of the length changes and isometry of the most frequently performed ligament reconstructions of the knee joint. The primary goal of this thesis was to improve our... Show moreThis thesis offers an overview of the length changes and isometry of the most frequently performed ligament reconstructions of the knee joint. The primary goal of this thesis was to improve our knowledge about the complex function of the anatomical ligaments of the knee. To study the length changes and isometry of the ligaments of the knee, we used a noninvasive imaging methodology to capture the in vivo biomechanics. Dual fluoroscopy was used to capture the in vivo joint motion and was combined with magnetic resonance (MR) or computed tomography (CT) imaging that were used to reconstruct the bony anatomy of the knee. To overcome the knee-to-knee differences, a quadrant method was used to apply the anatomical attachments of the ligaments to the 3-dimensional knee models. We studied the length changes and isometry of 1. anatomical anterior cruciate ligament and several locations on the medial aspect of the lateral femoral condyle to the anterior cruciate ligament attachment on the tibia; 2. the posterior cruciate ligament and several locations on the lateral aspect of the medial femoral condyle to the tibial attachment of the posterior cruciate ligament; 3. the anterolateral ligament and several locations on the lateral aspect of the lateral femoral condyle connected to the anatomic attachment of the anterolateral ligament on the tibia and Gerdy’s tubercle; and 4. The medial patellofemoral ligament and several locations on the medial aspect of the medial femoral condyle to the patellar medial patellofemoral ligament attachment. Optimal areas for the aforementioned ligaments of the knee were described. This newly gathered knowledge could improve the contemporary ligament reconstructions of the knee to reduce the amount of failed grafts related to tunnel malpositioning. Show less
This thesis examines how computer software can be used to analyse medical images of an aseptically loosening hip prosthesis, and subsequently to plan and guide a minimally invasive cement injection... Show moreThis thesis examines how computer software can be used to analyse medical images of an aseptically loosening hip prosthesis, and subsequently to plan and guide a minimally invasive cement injection procedure to stabilize the prosthesis. We addressed the detection and measurement of periprosthetic bone lesions from CT image volumes. Post-operative CTs of patients treated at our institution were analysed. We developed tissue classification algorithms that automatically label periprosthetic bone, cement and fibrous interface tissue. An existing particle-based multi-material meshing algorithm was adapted for improved Finite Element model creation. We then presented HipRFX, a proof-of-concept software tool for planning and guidance during percutaneous cement refixation procedures. Show less
Model-based shape matching is commonly used, for example to measure the migration of an implant with Roentgen stereophotogrammetric analysis (RSA) or to measure implant kinematics with fluoroscopy.... Show moreModel-based shape matching is commonly used, for example to measure the migration of an implant with Roentgen stereophotogrammetric analysis (RSA) or to measure implant kinematics with fluoroscopy. The aim of this thesis was to investigate the general usability of shape matching and to improve the reliability of shape matching for RSA and fluoroscopy. Several improvements were made to the usability and reliability of model-based shape matching for RSA and fluoroscopy. An automatic contour detection approach was proposed, integrating directly into the estimation of position and orientation of the implant. The accuracy of such estimation was also improved by taking the relation between implant parts into account. The robustness of model-based shape matching was assessed when it is applied fully automatically, demonstrating that manual supervision remains necessary. The standardization of validating new fluoroscopic methods could be a welcome addition to the biomechanical field, making it a lot easier to compare results between methods and experiments. As the technology of fluoroscopy advances, the amount of high quality data is getting larger, and may soon grow beyond the capabilities of manual, supervised pose estimation methods. It is therefore imperative that fully automatic unsupervised methods are developed. Show less
The focus of this thesis was if the in vivo kinematics of total knee prostheses was consistent with the kinematics intended by design and to determine the additional value of insert mobility and... Show moreThe focus of this thesis was if the in vivo kinematics of total knee prostheses was consistent with the kinematics intended by design and to determine the additional value of insert mobility and thus __the sense or nonsense__ of mobile-bearing knee prostheses. The added value of this thesis to the current literature is the integration of different measurement techniques. Fluoroscopy is combined with RSA and motion analysis techniques to fully understand the in vivo knee kinematics beyond which can be obtained by either technique alone. Results demonstrate that the integration of different measurement techniques was indeed of great value to comprehend the in vivo knee kinematics. Show less
The aim of the thesis was to to assess with accurate and objective methods the function and fixation of total knee prostheses with special emphasis on mobile bearing total knee designs. The mobile... Show moreThe aim of the thesis was to to assess with accurate and objective methods the function and fixation of total knee prostheses with special emphasis on mobile bearing total knee designs. The mobile bearing of a rotating platform design showed limited motion or no motion during a step-up task thereby nullifying the theoretical advantages of a mobile bearing prosthesis. Apatite coated implants show excellent mid-term Roentgen Stereophotogrammetric Analysis (RSA) results and offer some clinical advantages above cemented total knee arthroplasty. A prospective RSA study also revealed that the studied mobile bearing design is more predictable and forgiving with respect to micromotion of the tibial component than a posterior stabilised prosthesis. However, mobile bearing prostheses showed to be more demanding for the soft tissue structures surrounding the knee joint. The techniques used in gait analysis and fluoroscopy are sensitive for measurement errors. This restricts the applicability and interpretation of the results acquired when using these methods. In general one needs to be aware of the limitations of measurement tools since one needs accurate and objective methods to assess evidence about the clinical performance of (new) total knee prostheses. Show less
