A septic revision of an artificial joint is routinely split up in a so-called Nine fresh frozen cadaveric hips were used and primary THA was undertaken via a direct anterior approach. Before implantation of the components varying amounts of fluorescent powder (GloGerm) were deposited, simulating bacterial infection. Second, a one-step exchange was performed via a posterolateral approach. After implant removal, debridement, and lavage, randomization determined which clean phase protocol was followed, i.e. no, some or full additional measures. Finally, the new prosthesis was re-implanted (fig. 1). In order to determine the effect of different clean phase protocols on contamination of the sterile field standardized UV light-enhanced photographs were obtained of 1) the gloves, 2) the instrument table, 3) the drapes, and 4) the wound and these were ranked on cleanliness by a blind panel of hip surgeons. In order to determine whether or not it is possible to re-implant the prosthesis completely clean, the implant was taken out again at the end of the one-step exchange and inspected for contamination under UV light.Aim
Method
Degeneration of the shoulder joint is a frequent problem. There are two main types of shoulder degeneration: Osteoarthritis and cuff tear arthropathy (CTA) which is characterized by a large rotator cuff tear and progressive articular damage. It is largely unknown why only some patients with large rotator cuff tears develop CTA. In this project, we investigated CT data from ‘healthy’ persons and patients with CTA with the help of 3D imaging technology and statistical shape models (SSM). We tried to define a native scapular anatomy that predesignate patients to develop CTA. Statistical shape modeling and reconstruction:
A collection of 110 CT images from patients without glenohumeral arthropathy or large cuff tears was segmented and meshed uniformly to construct a SSM. Point-to-point correspondence between the shapes in the dataset was obtained using non-rigid template registration. Principal component analysis was used to obtain the mean shape and shape variation of the scapula model. Bias towards the template shape was minimized by repeating the non-rigid template registration with the resulting mean shape of the first iteration. Eighty-six CT images from patients with different severities of CTA were analyzed by an experienced shoulder surgeon and classified. CT images were segmented and inspected for signs of glenoid erosion. Remaining healthy parts of the eroded scapulae were partitioned and used as input of the iterative reconstruction algorithm. During an iteration of this algorithm, 30 shape components of the shape model are optimized and the reconstructed shape is aligned with the healthy parts. The algorithm stops when convergence is reached.Background
Methods
Glenosphere disengagement can be a potential serious default in reverse shoulder arthroplasty [1]. To ensure a good clinical outcome, it is important for the surgeon to obtain an optimal assembly of the glenosphere - base plate system during surgery. However interpositioning of material particles (bone, soft tissue) between the contact surface of the glenosphere and the base plate and/or a misalignment of the glenosphere relative to the base plate can result in a suboptimal assembly of the glenosphere – base plate system [2]. This misalignment is typically caused by unwanted contact between the glenosphere and the scapula due to inadequate reaming. Both defects prevent the Morse taper from fully engaging, leading to a system configuration for which the assembly was not designed to be loaded in vivo. This study quantifies the influence these defects have on the relative movement between the glenosphere and metaglene. A biaxial test setup [Fig. 1] was developed to mechanically load the glenoidal assembly (base plate + glenosphere) of 5 Depuy® Delta Xtend 38 prostheses. The setup allows applying a cyclic loading pattern to the glenoidal component with a constant actuator load of 750 N. Each of the 5 samples was tested for 5000 cycles on 3 defects: an interpositioning of 150 µm thick (0.48 mm3) and two local underreaming defects, pushing one side of the glenosphere up 0.5 mm and 1 mm respectively, hence causing a misalignment. The relative movement was recorded using 4 Linear Variable Differential Transducers (LVDTs). The cycling frequency is 1 Hz.INTRODUCTION
MATERIALS AND METHODS
