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In this double-blind randomised placebo-controlled trial it was investigated during a two-year follow-up whether oral bisphosphonates (Olpadronate 10 mg/m 2 /day) influence quality of life in children with osteogenesis imperfecta (OI). Thirty-four children with OI (classified according to Sillence criteria), aged 3 to 18 years of age, with a restricted level of ambulation were included. Randomisation was performed using a list of computer generated random numbers to allocate patients to receive Olpadronate or placebo. Quality of life was measured using self-perception profile for children (SPPC) and health-utility index (HUI). Differences between baseline measurements and measurements at two years follow-up were analysed within the Olpadronate and placebo group using a student's t-test. Differences in HUI and SPPC regression coefficients were analysed by random-effects repeated measures analysis (SAS, Proc Mixed, version 8.2), adjusted for age, gender and type of OI. Within the Olpadronate group there was a significant decrease in pain utility; however, difference in six months' regression coefficients between the placebo and Olpadronate group were not significant. Within the placebo group there was a significant increase in scholastic competence and behavioural conduct. The item behavioural conduct showed a steeper annual regression coefficient favourable for the placebo group. In the other SPPC items none of the annual regression coefficients showed a significant difference between the Olpadronate and the placebo group. Conclusion: We found only slight differences in quality of life in favour of the bisphosphonate group. A small but not significant decrease in pain was detected in the bisphosphonate group.

BackgroundSpinal systems that are currently available for correction of spinal deformities or degeneration such as lumbar spondylolisthesis or degenerative disc disease use components manufactured from stainless steel or titanium and typically comprise two spinal rods with associated connection devices (for example: DePuy Spines Titanium Moss Miami Spinal System). The Memory Metal Spinal System of this study consists of a single square spinal rod made of a nickel titanium alloy (Nitinol) used in conjunction with connecting transverse bridges and pedicle screws made of Ti-alloy. Nitinol is best known for its shape memory effect, but is also characterized by its higher flexibility when compared to either stainless steel or titanium. A higher fusion rate with less degeneration of adjacent segments may result because of the elastic properties of the memory metal. In addition, the use of a single, unilateral rod may be of great value for a TLIF procedure. Our objective is to evaluate the mechanical properties of the new Memory Metal Spinal System compared to the Titanium Moss Miami Spinal System.MethodsAn in-vitro mechanical evaluation of the lumbar Memory Metal Spinal System was conducted. The test protocol followed ASTM Standard F1717-96, “Standard Test Methods for Static and Fatigue for Spinal Implant Constructs in a Corpectomy Model.”1. Static axial testing in a load to failure mode in compression bending,2. Static testing in a load to failure mode in torsion,3. Cyclical testing to estimate the maximum run out load value at 5.0 x 10^6 cycles.ResultsIn the biomechanical testing for static axial compression bending there was no statistical difference between the 2% yield strength and the stiffness of the two types of spinal constructs.In axial compression bending fatigue testing, the Memory Metal Spinal System construct showed a 50% increase in fatigue life compared to the Titanium Moss Miami Spinal System.In static torsional testing the Memory Metal Spinal System constructs showed an average 220% increase in torsional yield strength, and an average 30% increase in torsional stiffness.ConclusionsThe in-vitro mechanical evaluation of the lumbar Memory Metal Spinal System showed good results when compared to a currently available spinal implant system. Throughout testing, the Memory Metal Spinal System showed no failures in static and dynamic fatigue.

Background and purpose — Osteogenesis imperfecta (OI) is a heritable disorder of connective tissue caused by a defect in collagen type I synthesis. For bone, this includes fragility, low bone mass, and progressive skeletal deformities, which can result in various degrees of short stature. The purpose of this study was to investigate development of bone mineral density in children with OI.Patients and methods — Development of lumbar bone mineral density was studied retrospectively in a cohort of 74 children with OI. Mean age was 16.3 years (SD 4.3). In 52 children, repeated measurements were available. Mean age at the start of measurement was 8.8 years (SD 4.1), and mean follow-up was 9 years (SD 2.7). A longitudinal data analysis was performed. In the total cohort (74 children), a cross-sectional analysis was performed with the latest-measured BMD. Age at the latest BMD measurement was almost equal for girls and boys: 17.4 and 17.7 years respectively.Result — Mean annual increase in BMD in the 52 children was 0.038 g/cm2/year (SD 0.024). Annual increase in BMD was statistically significantly higher in girls, in both the unadjusted and adjusted analysis. In cross-sectional analysis, in the whole cohort the latest-measured lumbar BMD was significantly higher in girls, in the children with OI of type I, in walkers, and in those who were older, in both unadjusted and adjusted analysis.Interpretation — During 9 years of follow-up, there appeared to be an increase in bone mineral density, which was most pronounced in girls. One possible explanation might be a later growth spurt and older age at peak bone mass in boys.