Marius von Knoch

Particle-Induced Osteolysis in Three-Dimensional Micro-Computed Tomography

Small-animal models are useful for the in vivo study of particle-induced osteolysis, the most frequent cause of aseptic loosening after total joint replacement. Microstructural changes associated with particle-induced osteolysis have been extensively explored using two-dimensional (2D) techniques. However, relatively little is known regarding the 3D dynamic microstructure of particle-induced osteolysis. Therefore, we tested micro-computed tomography (micro-CT) as a novel tool for 3D analysis of wear debris-mediated osteolysis in a small-animal model of particle-induced osteolysis. The murine calvarial model based on polyethylene particles was utilized in 14 C57BL/J6 mice randomly divided into two groups. Group 1 received sham surgery, and group 2 was treated with polyethylene particles. We performed 3D micro-CT analysis and histological assessment. Various bone morphometric parameters were assessed. Regression was used to examine the relation between the results achieved by the two methods. Micro-CT analysis provides a fully automated means to quantify bone destruction in a mouse model of particle-induced osteolysis. This method revealed that the osteolytic lesions in calvaria in the experimental group were affected irregularly compared to the rather even distribution of osteolysis in the control group. This is an observation which would have been missed if histomorphometric analysis only had been performed, leading to false assessment of the actual situation. These irregularities seen by micro-CT analysis provide new insight into individual bone changes which might otherwise be overlooked by histological analysis and can be used as baseline information on which future studies can be designed.

Misinterpretation of cup anteversion in total hip arthroplasty using planar radiography

IntroductionAnteroposterior pelvic radiographs are routinely used to monitor cup orientation in total hip arthroplasty (THA). Analysis of planar radiographs leads to a certain degree of measurement error for the cup anteversion (AV). With the current study, we wanted to clarify whether planar radiography can be used for accurate evaluation of the THA position.Materials and methodsThe postoperative orientation of pelvic implants in 42 patients was analyzed according to five documented mathematical algorithms using planar radiographs. Postoperative computed tomography (CT) pelvis scans were available for all patients. A CT-based navigation system was used to determine AV. ResultsThe comparison showed that all five formulas presented substantial variations for the AV angle. Of these, Widmer’s algorithm presented the smallest difference compared to the CT. Misinterpretation of postoperative planar radiographs is a common problem in THA.ConclusionPlanar radiographs are too imprecise for exact evaluation of the correct cup AV after THA. CT-based analysis may be necessary if exact values are required.

Extrinsic and intrinsic pathways of apoptosis in aseptic loosening after total hip replacement.

Particle-induced osteolysis is a major cause of aseptic loosening after total joint replacement. The purpose of the current study was to identify various apoptosis-related pathways in the cellular response to wear debris. Fas receptor, BAK and caspase-3 cleaved were evaluated immunohistochemically in capsules and interface membranes from patients with aseptic hip implant loosening. Moreover, we investigated local cellular proliferation, documented by the presence of Ki-67, to evaluate the proportion of apoptosis in relation to the proliferation in the different cells. We detected a strong expression of caspase-3 cleaved, Fas and BAK in macrophages, giant cells and T-lymphocytes. The fibroblasts showed caspase-3 cleaved and BAK, but no Fas staining. Demonstrated by Ki-67 staining, we found increased proliferation of macrophages and fibroblasts. Statistical analysis showed a significant positive correlation (p<0.001) between the above mentioned results and the presence of wear debris. The intensity of apoptosis and proliferation differed, depending on the extent of osteolysis. Overall, four different patterns of immunoreactivity were identified. We think, however, that in particle-induced osteolysis apoptosis is pathologically increased - a phenomenon also seen in other diseases. In these instances, the number and degree of apoptotic reactions are so great that the resulting cell remains cannot be completely removed. This leads to an increased excretion of fibrogenic mediators that could be responsible for increased proliferation of fibroblasts in spite of the increased apoptosis. Moreover, it leads to an increased excretion of cytokines which could be responsible for the activation of osteoclasts.

Digital templating in total hip arthroplasty with the Mayo stem

PatientsIn 40 patients undergoing total hip arthroplasty with the Mayo femoral stem we studied how preoperative digital templating corresponded to the actual intraoperative choice of implant size, position, offset and restoration of leg length.ResultsThe preoperatively planned sizes of the components showed a high rate of coincidence with the sizes used intraoperatively [Intraclass Correlation Coefficient (ICC) 0.661–0.810]. However, the agreements in offset and CCD correction were poor (ICC 0.476, 0.253). This could be statistically attributed to the change in the distance from the medial margin of the stem to the medial margin of the medial femoral cortex and the height of osteotomy. The agreement in leg length correction was moderate (ICC 0.583), which was attributed to the change in the hip rotation center and the height of osteotomy.ConclusionCareful preoperative planning was useful for accurate size choice of the Mayo prosthesis. Factors such as the height of osteotomy and the distance from the medial margin of the stem to the medial margin of the medial femoral cortex in relation to the position of the Mayo stem should be taken into account in order to restore ideal offset and leg length.

Polyethylene Particle–Induced Bone Resorption in α-Calcitonin Gene–Related Peptide–Deficient Mice†

This study investigates the impact of α‐CGRP on bone metabolism after implantation of polyethylene particles. α‐CGRP knockout mice showed less osteolysis compared with wildtype mice. The local neurogenic microenvironment might be a crucial factor in particle‐induced osteolysis.

Breakdance injuries and overuse syndromes in amateurs and professionals.

Background Serious injuries due to breakdancing have been presented only as singular case reports to date. So far, there have been no comprehensive studies about injuries in this sport. Hypothesis Professional breakdancing might lead to a higher incidence of injuries than amateur training. Wearing safety equipment is correlated with a decreased incidence of injuries and pain. Study Design Descriptive epidemiology study. Methods The retrospective study surveyed 40 breakdance professionals and 104 amateurs by questionnaire. Results There were 1665 injuries and 206 overuse syndromes found in 380 588 hours of training, leading to a loss of 10 970.6 training days. Professionals reported significantly (P < .001) more injuries and overuse syndromes with significantly more injuries of the wrist (P < .001), knee (P < .001), hip/thigh (P = .003), ankle/foot (P = .013), and elbow (P = .033). No significant differences were found in the time lost per injury and the time lost per overuse syndrome. Pain occurred most frequently in the region of the wrist, spine, shoulder, and ankle. A negative correlation between protective gear and injuries or frequency of pain could not be shown. Conclusion Breakdancing must be considered as a potentially high-risk dancing sport. Even with severe injuries, dancers interrupt training only for limited periods of time. Clinical Relevance Breakdance injuries and overuse should not be underestimated. Physicians should be aware of the common risks in this highly acrobatic kind of dancing.

Alumina ceramic particles, in comparison with titanium particles, hardly affect the expression of RANK‐, TNF‐α‐, and OPG‐mRNA in the THP‐1 human monocytic cell line

Particle-induced osteolysis is the most frequent cause of aseptic loosening after total joint replacement. We performed a study to illuminate the effect of ceramic particles with different diameters and concentrations on the mRNA expression of certain key regulators in particle-induced aseptic osteolysis (RANK, RANKL, OPG, and TNF-alpha) in THP-1 macrophage-like cells. Titanium particles were used as a positive control. RNA was analyzed by quantitative RTPCR. Our results demonstrate that alumina ceramic particles, regardless of particle size, caused only slight upregulations of RANK, TNF-alpha, and OPG mRNA, whose levels were significantly lower in comparison with those of titanium particles (p < 0.05). The continuous increasing tendency to time and particle-dependent mRNA expression of all the parameters stimulated by titanium particles was not found after stimulation with ceramic materials. Even after the concentration of ceramic particles was increased, only a mild upregulation of mRNA expression was found. Furthermore, we observed that the bioinert properties of ceramic particles did not change much in diameters ranging from 0.5 to 1.5 microm. At most of the measuring time points, there was no significant difference between the reactions of the large and small particles in this range. Our results support the theory about the relative bioinert properties of alumina ceramic particles.

Prognostic factors and therapeutic options for treatment of frozen shoulder: a systematic review.

PurposeTo evaluate the current status of scientific research on the natural history of frozen shoulder as published in the literature.Materials and methodsThis systematic review was carried out on PubMed data and was guided by PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Articles had to meet inclusion criteria. The quality of the papers was assessed using a newly developed tool, AMQPP (Assessing the Methodological Quality of Published Papers). The AMQPP score was correlated with the level of evidence rating according to the Oxford Centre for Evidence-Based Medicine. Suitable papers were divided into groups according to the shoulder condition on which they reported. This article focuses on the frozen shoulder.ResultsSeven articles on frozen shoulder met the inclusion criteria. One article was considered to have level 1 of evidence. Three articles had level 3 and the remaining 3 had level 4. Three papers assessed the natural history and the natural course of different forms of stiff shoulder. The others indirectly assessed the natural history by evaluating therapy trends. None of the articles clearly referred to the role of regression to the mean of frozen shoulder specifically.ConclusionSpontaneous recovery to normal levels of function is possible and standardised non-operative treatment programmes are an effective alternative to surgery in most cases. However, patients with high risk factors such as diabetes mellitus, and those who suffer chronic symptoms or bilaterally affected, would benefit from early surgery. We also concluded that AMQPP score is simple and straight forward. It works as a quick quality-checking tool which helps researchers to identify the key points in each paper and reach a decision regarding the eligibility of the paper more easily. The AMQPP score is still open for further development.

Calcitonin substitution in calcitonin deficiency reduces particle-induced osteolysis

BackgroundPeriprosthetic osteolysis is a major cause of aseptic loosening in joint arthroplasty. This study investigates the impact of CT (calcitonin) deficiency and CT substitution under in-vivo circumstances on particle-induced osteolysis in Calca -/- mice.MethodsWe used the murine calvarial osteolysis model based on ultra-high molecular weight polyethylene (UHMWPE) particles in 10 C57BL/6J wild-type (WT) mice and twenty Calca -/- mice. The mice were divided into six groups: WT without UHMWPE particles (Group 1), WT with UHMWPE particles (Group 2), Calca -/- mice without UHMWPE particles (Group 3), Calca -/- mice with UHMWPE particles (Group 4), Calca -/- mice without UHMWPE particles and calcitonin substitution (Group 5), and Calca -/- mice with UHMWPE particle implantation and calcitonin substitution (Group 6). Analytes were extracted from serum and urine. Bone resorption was measured by bone histomorphometry. The number of osteoclasts was determined by counting the tartrate-resistant acid phosphatase (TRACP) + cells.ResultsBone resorption was significantly increased in Calca -/- mice compared with their corresponding WT. The eroded surface in Calca -/- mice with particle implantation was reduced by 20.6% after CT substitution. Osteoclast numbers were significantly increased in Calca -/- mice after particle implantation. Serum OPG (osteoprotegerin) increased significantly after CT substitution.ConclusionsAs anticipated, Calca -/- mice show extensive osteolysis compared with wild-type mice, and CT substitution reduces particle-induced osteolysis.

The natural history of rotator cuff tears: a systematic review

PurposeTo analyse the current scientific evidence regarding the natural history of the clinical and anatomical progression of rotator cuff tears.MethodsA broad systematic review of the literature (PubMed database through January 2014) which was guided, conducted and reported according to PRISMA criteria. This article focuses on the rotator cuff tears. Articles had to meet an inclusion criteria. The methodological quality of each study was individually assessed using a recently developed general assessment tool AMQPP (assessing the methodological quality of published papers).ResultsSeven articles dealing with rotator cuff tears were included, one of them was a high-quality study. Three papers assessed the natural history and the natural course of rotator cuff rupture directly. The other studies indirectly assessed the natural history with reports on non-operative and operative therapy trends. All of these articles had been published in four different top medical journals according to 2013 ranking. We found no articles which clearly referred to the role of regression to the mean of rotator cuff tears.ConclusionThe development of symptoms and anatomical deterioration are often directly correlated. Spontaneous recovery to normal levels of function has been successfully achieved, and standardised non-operative treatment programmes are an effective alternative to surgery for many patients. Follow-up is necessary to avoid irreparable stage. However, surgery is still favoured by young active people and highly professional persons who need to get fit in a short period of time. Further research is still necessary. The AMQPP score system is simple and reliable. It works as a quick quality-checking tool which helps researchers to identify the key points in each paper and reach a decision regarding the eligibility of the paper more easily.