Peter R. Krekel

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Pre-operative planning systems aid clinicians by giving insight into patient-specific issues before surgery is performed. The ability to perform a virtual shoulder replacement procedure enables the surgeon to explore the probable and plausible outcomes. Pre-operative planning software assists the surgeon in this complex decision-making process. In our(More)
BACKGROUND The main cause for revision hip arthroscopy surgery is incomplete bony resection of femoroacetabular impingement (FAI). This study aimed to compare the cam resection accuracy via the conventional hip arthroscopy technique with the navigation technique. METHODS Two prospectively randomized groups were recruited: navigated (n = 15) and(More)
In shoulder arthroplasty, malpositioning of prostheses often leads to reduced postoperative range of motion (ROM) and complications such as impingement, loosening, and dislocation. Furthermore, the risk of impingement complications increases when reverse total prostheses are used. For this purpose a pre-operative planning system was developed that enables(More)
Kinematics is the analysis of motions without regarding forces or inertial effects, with the purpose of understanding joint behaviour. Kinematic data of linked joints, for example the upper extremity, i.e. the shoulder and arm joints, contains many related degrees of freedom that complicate numerical analysis. Visualisation techniques enhance the analysis(More)
INTRODUCTION Femoroacetabular impingement leads to limited hip motion, pain and progressive damage to the labrum. Assessment of the amount and location of excessive ossification can be difficult, and removal does not always lead to pain relief and an increase of function. One of the challenges ahead is to discover why certain cases have poor outcomes. (More)
Background Functional outcome in surgical treatment of Neer three-and four-part proximal humerus fractures (PHF) varies greatly and depends on multiple parameters. Important parameters are the amount and direction of displacement and the necessary reduction of fragments during surgery. These are patient-specific parameters and are difficult to determine(More)
Femoroacetabular impingement is a diagnosis that is often missed in patients with chronic groin pain. The condition often appears in young athletes. An anatomic deformity of the femoral head and the acetabular ridge causes an impingement that damages the subchondral tissue. This damage can result in sharp pain in the groin during specific hip movements and(More)
Shoulder joint replacement, or arthroplasty, is indicated in cases where arthritis or trauma has resulted in severe joint damage that in turn causes increased pain and decreased function. However , shoulder arthroplasty is less successful than hip and knee replacement, mostly due to the complexity of the shoulder joint and the resultant complexity of the(More)
Segmentation of rheumatoid joints from CT images is a complicated task. The pathological state of the joint results in a non-uniform density of the bone tissue, with holes and irregularities complicating the segmentation process. For the specific case of the shoulder joint, existing segmentation techniques often fail and lead to poor results. This paper(More)
BACKGROUND Femoroacetabular impingement (FAI) presupposes a dynamic interaction of the proximal femur and acetabulum producing clinical symptoms and chondrolabral damage. Currently, FAI classification is based on alpha angle and center-edge angle measurements in a single plane. However, acetabular and femoral version and neck-shaft angle also influence FAI.(More)