Percutaneous iliosacral fixation in external rotational pelvic fractures. A biomechanical analysis.

INTRODUCTION: Although the gold standard in open book pelvic fractures remains the pubic symphysis (PS) plate fixation, the clinical outcomes are not satisfactory, despite the excellent anatomical reduction assessed radiologically. Some authors suggest that residual instability of the posterior pelvic elements may be responsible for the chronic pain and the early osteoarthritic changes in the sacroiliac joint (SIJ). OBJECTIVE: To evaluate whether the isolated posterior fixation with one or two iliosacral screws (ISSs) is sufficient to provide adequate stability for the treatment of Burgess Young APC-II (YB APC-II) type of pelvic ring injuries. METHODS: Biomechanical experimental study using 7 fresh human pelvises, where an YB APC-II pelvic injury was previously implemented. The isolated posterior fixation of the pelvic ring with 1 or 2 ISSs directed in the S1 vertebra body was analysed in each specimen following an axial load of 300N. The different displacement of the SIJ and of the PS were analysed in all three spatial axes, using the validated optical measurement system 3D PONTOS 5M. A multivariate version of Friedman test (non-parametric ANOVA for repeated measures) was performed. RESULTS: The isolated fixation of the SIJ with 1 ISS did not show any differences with respect to the intact pelvis (p=0.851). Regarding the PS, both type of fixations (with 1 or 2 ISSs) confirmed an acceptable correction and adequate control of the PS even though with some differences compared to the intact pelvis (p=0.01). The presence of the second ISS found not to offer any significant additional benefit. The three-dimensional analysis of the behaviour of the pelvic elements, in these two different types of fixation, did not show any statistical significant differences (p=0.645). CONCLUSION: The posterior fixation with ISS can represent an alternative option for treatment of pelvic injuries associated with rotational instability. Further prospective clinical studies are necessary to determine, the influence of the residual pubic symphysis mobility in the every day life, when the above-mentioned technique is applied.

Bone health, daily physical activity, and exercise tolerance in patients with cystic fibrosis.

BACKGROUND: Daily physical activity (PA) may be an excellent tool for the maintenance of bone health in patients with cystic fibrosis (CF). The aim of this study was to analyze the possible association between physical capacity and activity and bone mineral density (BMD) in young adults with CF. A secondary goal was to evaluate vertebral fractures in this population. METHODS: A cross-sectional study was conducted in 50 patients with CF who were clinically stable and aged > 16 years but not lung transplant recipients. PA was quantified with a portable motion monitor (BodyMedia Fit Armband). Cardiopulmonary exercise and 6-min walk tests were used to assess exercise capacity. BMD was obtained from dual-energy x-ray absorptiometry of the lumbar column, hip, and whole body. To analyze vertebral fractures and deformity, we performed the Genant and Cobb methods. RESULTS: Daily PA time at low (3-4.8 metabolic equivalent tasks [METs]) and moderate (4.8-7.2 METs) intensity, respectively, was correlated with Z score (BMD) of the lumbar column (r = 0.36, P < .01 and r = 0.59, P < .001), the neck of femur (r = 0.51, P < .001 and r = 0.72, P < .001), and the total hip (r = 0.54, P < .001 and r = 0.74, P < .001). PA, BMI, age, and sex were predictors of BMD. Vertebral fractures correlated with kyphosis (r = 0.42, P = .02), but not with BMD. Patients who were mildly and severely affected differed in vertebral fracture rate and kyphosis prevalence (P = .002 and P = .013, respectively). CONCLUSIONS: The most active patients with better exercise capacity had higher BMD. Those with more affected pulmonary function had a greater prevalence of vertebral fractures and dorsal kyphosis.