Future burden of primary and revision hip arthroplasty in Germany: a socio-economic challenge.

INTRODUCTION: Total hip arthroplasty (THA) rates have increased dramatically in the recent decades worldwide, with Germany being one of the leading countries in the prevalence of THA. Simultaneously, a rising number of revision procedures is expected, which will put an enormous economic burden on future health care systems. METHODS: Nationwide data provided by the Federal Statistical Office of Germany were used to quantify primary and revision arthroplasty rates as a function of age and gender. Projections were performed with use of Negative Binomial and Poisson regression models on historical procedure rates in relation to population projections from 2020 to 2060. RESULTS: A 62% increase in the incidence rate of primary THAs is projected until 2060. At the same time, the annual total number of revision procedures is forecast to rise about 40% by the year 2060. The highest numbers of revision arthroplasties were calculated around year 2043. The greatest proportions of revision surgery will be observed in women and in those aged 70 years or older. The revision burden is projected to stabilize around 15% by 2060. CONCLUSIONS: The present projections allow a quantification of the increasing economic burden that (revision) THA will place on the German health care system in the upcoming decades. This study may serve as a model for other countries with similar demographic development as the country-specific approach predicts a substantial increase in the number of these procedures. This highlights the need for appropriate financial and human resource management in the future.

The crescent sign-a predictor of hip instability in magnetic resonance arthrography.

Currently, much is debated on the optimal treatment of borderline hips, being in the continuum between stable and unstable hips. The diagnosis of stability is often difficult but is a prerequisite for further treatment. Analysis includes a variety of radiographic parameters. We observed that unstable hips often had a crescent-like gadolinium collection in the postero-inferior joint space. We therefore questioned if the 'crescent sign' could be an indicator for hip instability? A retrospective comparative study was conducted including 56 hips in the instability group (treated with PAO) and 70 hips with femoroacetabular impingement (FAI) as control group. Based on standard radiographic parameters and magnetic resonance imaging (MRI), the association between hip instability and the 'crescent sign' was analyzed. For univariate group comparisons, the non-parametric Wilcoxon two sample test was used. Association between discrete variables was examined by means of chi-square tests. To examine predictive variables, logistic regression models were carried out. Most hips with a crescent sign belong to the instability group. A crescent sign has a sensitivity of 73.3% and specificity of 93% for instability. Based on our results, the crescent sign is a factor that is more prevalent in unstable hips. However, its absence does not exclude instability of the hip. If present, the specificity speaks strongly in favor for instability of the hip.

Assessment of early migration and clinical evaluation of a cemented femoral stem.

A 2-year follow-up study was conducted on 46 patients to assess Harris Hip Scores (HHS) and early distal migration of the femoral stem after total hip arthroplasty using a fully cemented femoral stem. The mean age was 73.4 years. The Fullfix stem (Mathys A.G., Bettlach, Switzerland) is characterised by a mat polished surface and a flange aimed to compress the cement during the insertion process. Early distal migration was determined in 36 patients using the computer assisted EBRA-FCA method (Einzel-Bild-Roentgen-Analyse femoral component analysis). At 2 years, subsidence reached a mean value of 0.44 mm (95% CI: 0.19, 0.70), whereafter the stem appeared stable, i.e. distal migration reached a plateau. Females showed significantly higher migration than males (p < 0.01). EBRA-FCA proved to be an accurate method to measure early migration, with a standard deviation below 1 mm (0.56 mm in the interval 1-2 years). Harris Hip Scores (HHS) at 2 years follow-up averaged 89.6 (95% CI: 79.5, 99.8). As expected considering the small extent of migration, there was no correlation between subsidence and HHS (p = 0.5).

Bone regeneration in long-bone defects: tissue compartmentalisation? In vivo study on bone defects in sheep.

Regeneration of living tissue varies with species, age and type of tissue, and undoubtedly with the biological and mechanical environment of the precise tissue. Autologous cancellous bone grafting is a well-known technique that provides bony regeneration. We investigated the efficiency of autologous bone grafting in a well-vascularised muscle environment, and additionally when isolated from the muscle and connected only to the bony environment. We designed a reproducible animal model producing a stable 3cm middiaphyseal bone and periosteal defect on sheep femurs and created a foreign-body membrane with a temporary poly-methylmethacrylate spacer. The foreign-body membrane had the outer dimension of the removed bone segment. We then ascertained the bony regeneration potential within the bone defect using autologous cancellous bone graft. Regeneration of bone is enhanced considerably by an autologous foreign-body membrane that separates the interfragmentary space from the muscular environment. This effect is independent of the autologous bone graft. The results suggest that bone behaves like a compartment that protects its specific humoral or its cellular environment, or both. Regeneration of bone can be enhanced by compartmentalisation of the bone defect.