Subchondral bone microarchitecture analysis in the proximal tibia at 7-T MRI

Salvaging Pull-Out Strength in a Previously Stripped Screw Site: A Comparison of Three Rescue Techniques

Screw stripping during bone fixation is a common occurrence during operations that results in decreased holding capacity and bone healing. We aimed to evaluate the rescue of the stripped screw site using screws of different dimensions. Five screw configurations were tested on cadaveric specimens for pull-out strength (POS). The configurations included a control screw tightened without stripping, a configuration voluntarily stripped and left in place, and three more configurations in which the stripped screws were replaced by a different screw with either increased overall length, diameter, or thread length. Each configuration was tested five times, with each screw tested once. The POS of the control screw, measured to be 153.6 ± 27 N, was higher than the POS measured after stripping and leaving the screw in place (57.1 ± 18 N, p = 0.001). The replacement of the stripped screw resulted in a POS of 158.4 ± 64 N for the screw of larger diameter, while the screws of the same diameter but increased length or those with extended thread length yielded POS values of 138.4 ± 42 and 185.7 ± 48 N, respectively. Screw stripping is a frequent intraoperative complication that, according to our findings, cannot be addressed by leaving the screw in place. The holding capacity of a stripped screw implanted in cancellous bone can successfully be restored with a different screw of either larger diameter, longer length, or extended thread length.

Survey of MRI Usefulness for the Clinical Assessment of Bone Microstructure

Bone microarchitecture has been shown to provide useful information regarding the evaluation of skeleton quality with an added value to areal bone mineral density, which can be used for the diagnosis of several bone diseases. Bone mineral density estimated from dual-energy X-ray absorptiometry (DXA) has shown to be a limited tool to identify patients’ risk stratification and therapy delivery. Magnetic resonance imaging (MRI) has been proposed as another technique to assess bone quality and fracture risk by evaluating the bone structure and microarchitecture. To date, MRI is the only completely non-invasive and non-ionizing imaging modality that can assess both cortical and trabecular bone in vivo. In this review article, we reported a survey regarding the clinically relevant information MRI could provide for the assessment of the inner trabecular morphology of different bone segments. The last section will be devoted to the upcoming MRI applications (MR spectroscopy and chemical shift encoding MRI, solid state MRI and quantitative susceptibility mapping), which could provide additional biomarkers for the assessment of bone microarchitecture.

Effects of a 12-Month Supervised, Community-Based, Multimodal Exercise Program Followed by a 6-Month Research-to-Practice Transition on Bone Mineral Density, Trabecular Microarchitecture, and Physical Function in Older Adults: A Randomized Controlled Trial

Multicomponent exercise programs are recommended to reduce fracture risk; however, their effectiveness in real-world community settings remain uncertain. This 18-month randomized controlled trial investigated the effects of a 12-month, community-based, supervised multicomponent exercise program followed by a 6-month "research-to-practice" transition on areal bone mineral density (BMD), trabecular bone microarchitecture, functional performance, and falls in older adults at increased fracture risk. One-hundred and sixty-two adults aged ≥60 years with osteopenia or at increased falls risk were randomized to the Osteo-cise: Strong Bones for Life multicomponent exercise program (n = 81) or a control group (n = 81). Exercise consisted of progressive resistance, weight-bearing impact, and balance training (3-days/week) performed at community leisure centers. Overall 148 (91%) participants completed the trial, and mean exercise adherence was 59% after 12 months and 45% during the final 6 months. After 12 months, there were significant net beneficial effects of exercise on lumbar spine and femoral neck BMD (1.0% to 1.1%, p < 0.05), muscle strength (10% to 13%, p < 0.05), and physical function (timed stair climb 5%; four-square step test 6%; sit-to-stand 16%, p ranging <0.05 to <0.001), which persisted after the 6-month transition. There were no significant effects of the 18-month intervention on distal femur or proximal tibia trabecular bone microarchitecture or falls incidence, but per protocol analysis (≥66% exercise adherence) revealed there was a significant net benefit of exercise (mean [95% confidence interval] 2.8% [0.2, 5,4]) on proximal tibia trabecular bone volume fraction (Osteo-cise 1.5% [-1.2, 4.2]; controls -1.3% [-2.6, 0.1]) after 18 months due to changes in trabecular number (Osteo-cise 1.7% [-0.9, 4.3]; controls -1.1% [-2.4, 0.2]) but not trabecular thickness (Osteo-cise - 0.2% [-0.5, 0.2]; controls -0.2% [-0.4, 0.0]). In conclusion, this study supports the effectiveness of the Osteo-cise: Strong Bones for Life program as a real-world, pragmatic, evidence-based community exercise program to improve multiple musculoskeletal health outcomes in older adults at increased fracture risk. © 2019 American Society for Bone and Mineral Research.