Introduction

Austin Moore cervicocephalic prostheses have been a therapeutical option for femoral neck fractures in patients with a reduced general condition for many years. Since treatments other than total hip arthroplasties have also been included in National arthroplasty registers during the last decade, adequate reference data for comparative analyses have recently become available.

Background: Implant fractures are complications that have a great impact on the patient’s quality of life after total hip arthroplasty. Nevertheless their occurrence is often considered as rare in clinical practice. We compared incidences of implant fractures in various datasets in order to calculate the risk of a fracture and assess the quality of these datasets for such evaluations.

Methods: In a structured literature analysis based on a standardised methodology the incidence of reoperations was evaluated comparing clinical studies published in Medline-listed journals and annual reports of National Arthroplasty Registers worldwide. Case reports and experimental studies were not considered.

Results: The majority of clinical studies are monocentre trials. The publications comprise a cumulative number of 72,571 stems with 234 stem fractures, 73,743 cups with 191 component fractures, and 16,381 ceramic heads with 44 fractures. A survey among the members of the American Association of Hip and Knee Surgeons covered 64,483 primary operations, hence including a similar number of primary cases as all monocentre studies together. This dataset involves 355 implant fractures.

By contrast, worldwide Register data refer to 733,000 primary operations, i.e. approximately 10 times as many as sample-based datasets.

In general, sample-based datasets present higher revision rates than register data. The deviations are high, with a maximum factor of 64 for hip stems. Whereas the AAHKS survey exhibits lower deviations than the monocentre trials, they are still too high for this data collection tool being considered as reliable and safe to provide valid data for general conclusions.

The incidence of implant fractures after total hip arthroplasty in pooled worldwide arthroplasty register datasets is 304 fractures per 100.000 implants. In other words, one out of 323 patients has to undergo revision surgery due to an implant fracture after THA in their lifetime.

Conclusion: For general assessments in the context of implant fractures, register data have the highest value. Clinical studies, which often focus on a particular implant, are of very limited value for global conclusions. Structured surveys produce more reliable data than clinical studies and are superior to monocentre trials. However, the AAHKS survey presents data that also show considerable differences to data from registers.

For the detection of rare, but severe complications like implant fractures sample-based studies achieve the goal of providing accurate figures only to a very limited extent, even if the samples are large. Here, too, comprehensive national arthroplasty registers are the most suitable tool to identify such incidents and calculate reliable figures.

Contrary to the prevalent opinion, implant fractures still are a relevant problem in arthroplasty.

Background: Within the scope of the EU project EUPHORIC a methodology for direct comparison of different datasets was developed and applied on a sample of implants, among them the Oxford Unicompartmental Knee Arthroplasty (Oxford Uni). The aim was to identify potential bias factors inherent in the datasets and evaluate the outcome achieved with this implant.

Materials and Methods: A structured comparison was performed of data published on the revision rate of the Oxford Unicompartmental prosthesis. Both clinical follow-up studies published in Medline-listed journals and worldwide Register data were included. The data were stratified with regard to potential influence factors like the individual research groups or the geographical origin of the papers.

Results: A major proportion of the published data, between 50 and 75%, depending on the method of calculation, comes from studies including the developing institution in Oxford. The results published by this group deviates statistically significantly from the reference datasets from Register data or independent research groups. Data from the developing hospital show mean revision rates that are 4.4 times lower than those based on worldwide Register data, and 2.74 times lower than in independent studies. As opposed to this, independent studies on average publish data that are reproducible in Register data.

Conclusion: A conventional meta-analysis of clinical studies is significantly affected through the influence of the developing institution and is therefore subject to a bias. Neither through arthroplasty Register outcome data nor by other research groups that have disclosed outcome information on the Oxford Uni can the excellent results be reproduced that were published by the inventors.

Compared to other implants for unicompartmental knee arthroplasty in worldwide arthroplasty Registers, the Oxford Uni shows good results.

For the assessment of the outcome of implants, register data are to be rated superior and, in terms of reference data for the detection of potential bias factors in the clinical literature, can provide an essential contribution for scientific meta-analyses.

Introduction: Clinical follow-up studies are sample based, in contrast to arthroplasty register data, which refer to the entire population treated. Aim of this study is to assess the differences in revision rate to quantify bias-factors in published literature.

Materials and Methods: A structured literature review of Medline-listed peer reviewed journals on examples has been performed concerning implants with sufficient material in both data sources available. Products with inferior outcome were subsumed in a subgroup.

Results: The number of cases presented in peer reviewed journals are relatively low in general and show a high variability.

The average revision rate in peer reviewed literature is significantly lower than in arthroplasty register data-sets.

Studies published by the inventor of an implant tend to show superior outcome compared to independent publications and Arthroplasty Register data. Factors of 4 to more than 10 have been found, which has a significant impact for the results of Metaanalyses.

When an implant is taken from the market or replaced by a successor there is a significant decrease in publications, which limits the detection of failure mechanisms such as PE wear or insufficient locking mechanisms.

The final statement made about the product under investigation seem to follow a certain mainstream.

Discussion and Conclusion: Arthroplasty Register datasets are superior to Metaanalyses of peer reviewed literature concerning revision rate and the detection of failure mechanisms. Combined reviews could reduce bias factors and thereby raise the quality of reports.

Introduction: Clinical follow-up studies are sample based, in contrast to arthroplasty register data, which refer to the entire population treated. Aim of this study is to assess the differences in revision rate to quantify bias-factors in published literature.

Materials and Methods: A structured literature review of Medline-listed peer reviewed journals concerning the STAR Total Ankle Replacement have been conducted.

The published results from clinical follow up studies have been compared to Arthroplasty register Results: Results: 24% of all papers were published by the inventor of the implant.

These publications show a 3,4 times lower revision rate compared to independent studies and a 4,6 times lower revision rate compared to Register based publications.

The cumulative revision rate per 100 observed component years of register based publications is 1,36 times higher compared to independent clinical studies. The difference is statistically not significant.

Pooling the published data from all follow up studies the impact of the studies published by the inventor leads to a statistically significant bias.

Discussion and Conclusion: Publications by the inventor of the implant are overrepresented in peer reviewed scientific journals. This bias has a statistically significant impact on the final result of a Metaanalyses.

Arthroplasty Register data are able to detect bias factors and lead to a better quality of assessments concerning the outcome of arthroplasty.

Aim of the study: Due to the fact, that there is no publication in Medline available concerning the influence of external compression of the wound area after total hip arthroplasty we started a prospective, randomised study to evaluate this effect.

Materials and Methods: In a prospective randomised study including primary total hip replacements we compared 2 different prefabricated compression bandages, maintaining different levels of pressure on the wound area(Group A, B), a group with circular semi elastic bandages (group C) and a group without any bandage (group D). The sample calculated for each group was 130 Patients (level of significance 0.05, power 90%). Parameters concerning postoperative blood loss (haematocrit, need of blood units, blood in drainage) and wound heeling (bleeding of wound area, secretion, haematoma, additional need of antibiotics) were measured. For statistical evaluations Chi²-Test and T-Test were used.

Results: The group using semi elastic, circular bandages (C ) had to be stopped after 13 patients due to non-compliance of more than 50% of the patients because of discomfort and skin lesions. Without compression bandage the frequency of re-operations due to early septic complications was statistically significant higher than in groups using external compression. In the groups B and D the rates of wound secretion have been significantly higher than in group A using high pressure bandages. Duration and quantity of secretion, need of additional antibiotics as well as subcutaneous haematoma were increasing by decreasing external compression. The amounts of blood in Redon drainage were significantly reduced by external compression. In regard to the need of blood units no statistical differences could be detected.

Conclusion: Sufficient compression bandages are able to significantly reduce the frequency of re-operations due to septic complications and support wound healing after total hip arthroplasty. A remarkable number of insufficient products are sold on the market.

Aims: To evaluate the inßuence of simultaneous local anesthesia (LA) on the clinical outcome after repetitive low-energy extracorporeal shock wave application (ESWT) for chronic plantar fasciitis. Methods: A prospective randomized observer-blinded pilot trial was performed in 48 painful heels (40 patients), having been resistant to various conservative treatment procedures for more than 6 months. 24 heels (20 patients) received 3 applications of 1500 impulses of 0.4 mJ/mm2 without LA (Group I)on 3 consecutive days with a conventional ultrasound-guided orthopaedic shock wave device (Sonocur plus, Siemens AG, Erlangen, Germany). 24 heels (20 patients) received 3 applications of 1500 impulses of 0.04 mJ/mm2 with LA on 3 consecutive days (Group II). Main outcome measure was the number of good or excellent outcomes needing no further therapy at three month follow-up. Secondary outcome measure was pain after weightbearing assessed on a visual analog scale (VAS; range, 0–10). Both groups did not differ signiþcantly before the start of the trial. Results: In Group I 16 of 24 (67%) heels reached a good or excellent result, in Group II 7 of 24 heels (29%) at three-month follow-up (p= 0.0199 for difference between groups; difference= 0.38; 95%CI= 0.09 to 0.66). Pain after weightbearing was 2.2±2.6 on a VAS in Group I, and 3.8±2.5 on a VAS in Group II (p= 0.0318 for difference between groups; mean difference= 0.16; 95%CI= 0.01 to 0.30). Conclusions: The simultaneous use of local anesthesia has a negative inßuence on repetitive low-energy shock wave therapy for chronic plantar fasciitis. Further prospective studies should be performed to evaluate more exactly the extent of this negative inßuence.