Distal Tibial Bone Properties and Bone Stress Injury Risk in Young Men Undergoing Arduous Physical Training

Trabecular microarchitecture contributes to bone strength, but its role in bone stress injury (BSI) risk in young healthy adults is unclear. Tibial volumetric BMD (vBMD), geometry, and microarchitecture, whole-body areal BMD, lean and fat mass, biochemical markers of bone metabolism, aerobic fitness, and muscle strength and power were measured in 201 British Army male infantry recruits (age 20.7 [4.3] years, BMI 24.0 ± 2.7 kg·m2) in week one of basic training. Tibial scans were performed at the ultra-distal site, 22.5 mm from the distal endplate of the non-dominant leg using High Resolution Peripheral Quantitative Computed Tomography (XtremeCT, Scanco Medical AG, Switzerland). Binary logistic regression analysis was performed to identify associations with lower body BSI confirmed by MRI. 20 recruits (10.0%) were diagnosed with a lower body BSI. Pre-injured participants had lower cortical area, stiffness and estimated failure load (p = 0.029, 0.012 and 0.011 respectively) but tibial vBMD, geometry, and microarchitecture were not associated with BSI incidence when controlling for age, total body mass, lean body mass, height, total 25(OH)D, 2.4-km run time, peak power output and maximum dynamic lift strength. Infantry Regiment (OR 9.3 [95%CI, 2.6, 33.4]) Parachute versus Line Infantry, (p ≤ 0.001) and 2.4-km best effort run time (1.06 [95%CI, 1.02, 1.10], p < 0.033) were significant predictors. Intrinsic risk factors, including ultradistal tibial density, geometry, and microarchitecture, were not associated with lower body BSI during arduous infantry training. The ninefold increased risk of BSI in the Parachute Regiment compared with Line Infantry suggests that injury propensity is primarily a function of training load and risk factors are population-specific.

Effectiveness of parathyroid hormone (PTH) analogues on fracture healing: a meta-analysis

This meta-analysis evaluated the evidence for the use of parathyroid hormone (PTH) analogues to improve fracture healing. Eligible studies were prospective randomised controlled trials of adults with acute fractures treated with a PTH analogue. PTH improved functional outcomes but did not affect fracture healing rate or reduce pain.

PURPOSE

This meta-analysis evaluated the evidence of parathyroid hormone (PTH) analogues in fracture healing. The use of PTH analogues to prevent osteoporotic fractures is well investigated, and studies are emerging on extended indications. One such indication receiving increasing attention is the effect of PTH in fracture healing; however, the overall degree of efficacy remains inconclusive.

METHODS

A systematic electronic database search of MEDLINE, EMBASE and the Cochrane Library was conducted for relevant articles in August 2019 with no date restrictions. Randomised controlled trials of adults with acute fractures treated with a PTH analogue were included. PTH was compared with a comparator intervention, placebo or no treatment.

RESULTS

PTH analogue treatment improved functional outcomes in a range of fracture types but did not affect the fracture healing rate or reduce pain. Most trials included in this review were in elderly patients with osteoporosis. There was no evidence that PTH treatment caused harm or impeded fracture healing.

CONCLUSIONS

Meta-analysis of published data supports the use of PTH analogues to improve functional outcomes but not fracture healing rate or pain for different fracture types. The evidence for PTH analogue use in fracture healing is less clear in younger, non-osteoporotic patient populations. Trial design was heterogeneous and of limited quality, justifying further original trials.

Mouth cell collection device for newborn mice

For efficient and accurate genotyping of transgenic and knockout mice, the ability to reduce pain and suffering and to obtain DNA early in life are critical. We have developed a novel method to sample buccal cells from neonatal mice to obtain DNA. Our mouse mouth cell collection process includes an oral speculum and collection device which enables rapid extraction of enough DNA for up to 50 PCRs from each buccal sampling. This cell collection device fills a clear need for buccal sampling from neonatal mice, greatly facilitating research in mouse models of human disease. Eliminating the pain, distress, and death caused by invasive and mutilating procedures lessens the potential for confounding variables between control and experimental animals. In conclusion, our mouse mouth cell collection process can be applied to very small animals for which there exists no current device.

The effects of common movement and spatial separation on position- and motion-based judgements of relative movement

When common movement is superimposed on relative movement (changes in separation between two dots), relative movement thresholds increase nonlinearly as a function of initial dot separation. For large separation (greater than 2.0 deg), thresholds increase gradually with increased separation. It is shown that this reflects judgments based on perceived relative motion. For small separations (less than 2.0 deg), thresholds increase sharply with increased separation. It is shown that this reflects judgments based on perceived changes in relative position. Evidence is presented that superimposed common movement reduces sensitivity to relative movement by reducing sensitivity to relative motion. This provides a "window", in the range of small dot separations, for relative movement judgements to be based on the perception of changes in relative position, even though motion is perceived for individual dots.