Breaking strength and bone microarchitecture in osteoporosis: a biomechanical approximation based on load tests in 104 human vertebrae from the cervical, thoracic, and lumbar spines of 13 body donors.

BACKGROUND: The purpose of the study was to investigate associations between biomechanical resilience (failure load, failure strength) and the microarchitecture of cancellous bone in the vertebrae of human cadavers with low bone density with or without vertebral fractures (VFx). METHODS: Spines were removed from 13 body donors (approval no. A 2017-0072) and analyzed in regard to bone mineral density (BMD), Hounsfield units (HU), and fracture count (Fx) with the aid of high-resolution CT images. This was followed by the puncture of cancellous bone in the vertebral bodies of C2 to L5 using a Jamshidi™ needle. The following parameters were determined on the micro-CT images: bone volume fraction (BVF), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), degree of anisotropy (DA), trabecular number (Tb.N), trabecular pattern factor (Tb.Pf), and connectivity density (Conn.D). The axial load behavior of 104 vertebral specimens (C5, C6, T7, T8, T9, T12, L1, L3) was investigated with a servohydraulic testing machine. RESULTS: Individuals with more than 2 fractures had a significantly lower trabecular pattern factor (Tb.Pf), which also proved to be an important factor for a reduced failure load in the regression analysis with differences between the parts of the spine. The failure load (FL) and endplate sizes of normal vertebrae increased with progression in the craniocaudal direction, while the HU was reduced. Failure strength (FS) was significantly greater in the cervical spine than in the thoracic or lumbar spine (p < 0.001), independent of sex. BVF, Tb.Th, Tb.N, and Conn.D were significantly higher in the cervical spine than in the other spinal segments. In contrast, Tb.Sp and Tb.Pf were lowest in the cervical spine. BVF was correlated with FL (r = 0.600, p = 0.030) and FS (r = 0.763, p = 0.002). Microarchitectural changes were also detectable in the cervical spine at lower densities. CONCLUSIONS: Due to the unique microarchitecture of the cervical vertebrae, fractures occur much later in this region than they do in the thoracic or lumbar spine. Trial registration Approval no. A 2017-0072.

Biomechanics of the osteoporotic spine, pain, and principles of training.

INTRODUCTION: A fracture is a clinical manifestation of osteoporosis and is one of the main causes of functional limitations and chronic pain in patients with osteoporosis. Muscle and coordination training are recommended to the patients as general measures. We inquired whether sling training is better than traditional physiotherapy in relieving pain and improving abilities of daily living. METHODS: Fifty patients with osteoporosis were divided into two groups. Group A performed conventional physiotherapy, while Group B performed sling training exercises. Data were collected before and after the intervention and after 3 months. The registered parameters were stamina, posture, and pain. Posture, torques, and the associated strength of spinal muscles were studied in a biomechanical model in order to estimate the forces acting on the spine. Furthermore, the factors that exerted a positive impact on the success of therapy were registered. RESULTS: Forty-four patients (88%) completed the study. Positive effects of the training were noted in both groups, but significantly better effects were observed in the group that performed sling training. A reduction of pain independent of the number of fractures, significantly reduced torques, and reduced muscle strength were registered. CONCLUSIONS: Specific training programs helped to increase muscle strength and straightening the back thereby reducing the force needed on a permanent basis and decreasing torque in the spine. Sling training was more effective in that than traditional physiotherapy.

Previous malignancy is an independent predictor of follow-up mortality after percutaneous treatment of mitral valve regurgitation by means of MitraClip.

AIMS: To investigate the prognostic burden of previously diagnosed and treated malignancies in candidates for percutaneous mitral valve repair (MVR) with MitraClip. METHODS AND RESULTS: A total of 165 patients underwent MVR and 19 (11.5%) had been previously treated for malignancy and considered healed with life expectancy over 1 year at time of percutaneous MVR. There was a significant trend for an increased overall risk profile (euroSCORE II 14.0±11.4 vs 10.0±6.7, P=.01) in patients with a previous diagnosis of neoplasia. Moreover, neoplastic patients had lower device success rates (78.9% vs 97.3%; P=.001), longer hospitalization (12.3±10.6 vs 7.5±4.9 days, P=.001), and higher 30-day mortality (10.5% vs 2.7%, P=.09). Kaplan-Meier overall estimated 1-, 2-, 3-, and 4-year survival of the overall cohort was 72%, 61%, 48%, and 44%, respectively. Estimated 1- and 2-year survival were 44.4% and 22.2 % in patients with previous neoplasia and 75.3% and 65% in the remaining patients (P<.0001). Median survival was 312 days in the neoplastic group (CI 95%: 182.6-441.4 days) and 1209 days in the remaining patients (CI 95%: 758.8-1659.2 days) (P<.0001). At Cox regression, the strongest determinant for mortality was an anamnesis for neoplasia (HR 2.4, 95% CI 1.4-4.3, P=.001). CONCLUSIONS: Previous neoplasm is a significant independent predictor of increased mortality after MVR with MitraClip. This association is even stronger than that of other cardiac and overall comorbidities and should be kept into consideration when referring patients for treatment.