Current Pathologic Scoring Systems for Metal-on-metal THA Revisions are not Reproducible

Development and application of statistical models for medical scientific researc

Hydroxyapatite-coated uncemented hip stems and bone remodeling

In this thesis the clinical results, the periprosthetic bone remodeling and histological analysis of an anatomical designed proximally hydroxyapatite-coated hip prosthesis were investigated to answer several research questions. In our first prospective study the characteristics of the bone remodeling pattern around an uncemented anatomical, proximally coated stem (ABG-I) and its successor (ABG-II) were described using DEXA. ABG-II showed less bone loss proximally, especially in zone 7. However, the difference found for the proximal zone 7 was not significant In our second study, patients were retrospectively matched for preoperative bone quality and gender. Now, a statistically significant difference was found in proximal bone preservation in favor of ABG-II for zone 7. These findings support our conclusion that in comparative bone remodeling studies for prosthetic design using DEXA, patients should be matched for preoperative bone quality and gender to limit the number of patients while maintaining maximum statistical power. Bone remodeling can also be influenced by tightness of stem fit and therefore we assessed the radiological changes five years after implantation of the stem (third study). We investigated if there was a correlation between a tight fit and the bone remodeling pattern. In this study there was no correlation between fit and radiological changes, but there was a correlation between a poor fit and thigh pain for the ABG-II stem. In the fourth study bone remodeling was assessed by histomorphometric analysis of a proximally HA-coated stem (ABG-I). In this study the HA residue was measured histomorphometrically on hip stems of one single design (ABG-I) retrieved at post-mortem, and the long-term performance of the HA coating and the effects of resorption were investigated. HA resorption increased significantly with the time in vivo as measured by the residual HA. Beyond 8 years HA was almost gone. HA resorption was significantly more proximal than distal, an effect which was less strong with bone ongrowth. Bone ongrowth was statistically independent of the time in-vivo. Bone ongrowth was significantly less with older patients. In the fifth and last study periprosthetic fractures around an uncemented proximally coated stem are described. The fracture patterns were analyzed by reviewing the X-rays in detail and the modified Vancouver classification was retrospectively applied for these fractures. An increased number of periprosthetic fractures for the ABG-I stem compared to the cemented stem was shown. The site of the fracture in our series was always localized in an area where an acute bone density gradient in the cortex had developed, between the proximal and the middle Gruen zones. The retrospectively applied Vancouver classification turned out to be a simple, reproducible classification system for the uncemented treatment modality, which will make clinical decision-making easier. All studies performed point in the same direction: proximal bone loss for the ABG stem and less proximal bone loss for the ABG-II stem compared to the ABG-I stem. Despite this proximal bone resorption, clinical follow up shows excellent results after ten years for the ABG-I stem. Its successor (ABG-II) shows less proximal bone resorption, but a relatively high percentage of thigh pain. Long term follow-up studies should provide more information as to whether less proximal bone resorption (ABG-II) will also lead to better clinical performance. Stress shielding is and will remain an important issue in total hip arthroplasty for the long term

Long-term results of total hip arthroplasty with the CementLess Spotorno (CLS) system

Orthopaedics, Trauma Surgery and Rehabilitatio

Pseudotumor in metal-on-metal hip arthroplasty: a comparison study of three grading systems with MRI

Development and application of statistical models for medical scientific researc

Study protocol: Effectiveness of dual-mobility cups compared with uni-polar cups for preventing dislocation after primary total hip arthroplasty in elderly patients - design of a randomized controlled trial nested in the Dutch Arthroplasty Registry

Background and purpose - Dislocation is the leading reason for early revision surgery after total hip arthroplasty (THA). The dual-mobility (DM) cup was developed to provide more stability and mechanically reduce the risk of dislocation. Despite the increased use of DM cups, high-quality evidence of their (cost-)effectiveness is lacking. The primary objective of this randomized controlled trial (RCT) is to investigate whether there is a difference in the number of hip dislocations following primary THA, using the posterolateral approach, with a DM cup compared with a unipolar (UP) cup in elderly patients 1 year after surgery. Secondary outcomes include the number of revision surgeries, patient-reported outcome measures (PROMs), and cost-effectiveness.Methods and analysis - This is a prospective multicenter nationwide, single-blinded RCT nested in the Dutch Arthroplasty Registry. Patients >= 70 years old, undergoing elective primary THA using the posterolateral approach, will be eligible. After written informed consent, 1,100 participants will be randomly allocated to the intervention or control group. The intervention group receives a THA with a DM cup and the control group a THA with a UP cup. PROMs are collected preoperatively, and 3 months, 1 and 2 years postoperatively. Primary outcome is the difference in number of dislocations between the UP and DM cup within 1 year, reported in the registry (revisions), or by the patients (closed or open reduction). Data will be analyzed using multilevel models as appropriate for each outcome (linear/logistic/survival). An economic evaluation will be performed from the healthcare and societal perspective, for dislocation and quality adjusted life years (QALYs).Orthopaedics, Trauma Surgery and Rehabilitatio

Radioimmunotherapy of methicillin-resistant Staphylococcus aureus in planktonic state and biofilms

Background Implant associated infections such as periprosthetic joint infections are difficult to treat as the bacteria form a biofilm on the prosthetic material. This biofilm complicates surgical and antibiotic treatment. With rising antibiotic resistance, alternative treatment options are needed to treat these infections in the future. The aim of this article is to provide proof-of-principle data required for further development of radioimmunotherapy for non-invasive treatment of implant associated infections. Methods Planktonic cells and biofilms of Methicillin-resistant staphylococcus aureus are grown and treated with radioimmunotherapy. The monoclonal antibodies used, target wall teichoic acids that are cell and biofilm specific. Three different radionuclides in different doses were used. Viability and metabolic activity of the bacterial cells and biofilms were measured by CFU dilution and XTT reduction. Results Alpha-RIT with Bismuth-213 showed significant and dose dependent killing in both planktonic MRSA and biofilm. When planktonic bacteria were treated with 370 kBq of 213Bi-RIT 99% of the bacteria were killed. Complete killing of the bacteria in the biofilm was seen at 185 kBq. Beta-RIT with Lutetium-177 and Actinium-225 showed little to no significant killing. Conclusion Our results demonstrate the ability of specific antibodies loaded with an alpha-emitter Bismuth-213 to selectively kill staphylococcus aureus cells in vitro in both planktonic and biofilm state. RIT could therefore be a potentially alternative treatment modality against planktonic and biofilm-related microbial infections.Biomaterials & Tissue Biomechanic