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Comprehensive treatment for vertebral metastatic lesions commonly involves vertebral augmentation (vertebroplasty or kyphoplasty) to relieve pain and stabilize the spine followed by multiple sessions of radiotherapy. We propose to combine vertebral augmentation and radiotherapy into a single treatment by adding32P, aβ-emitting radionuclide, to bone cement, thereby enabling spinal brachytherapy to be performed without irradiating the spinal cord. The goal of this study was to address key dosimetry and safety questions prior to performing extensive animal studies. The32P was in the form of hydroxyapatite powder activated by neutron bombardment in a nuclear reactor. We performedex vivodosimetry experiments to establish criteria for safe placement of the cement within the sheep vertebral body. In anin vivostudy, we treated three control ewes and three experimental ewes with brachytherapy cement containing 2.23-3.03 mCi32P ml-1to identify the preferred surgical approach, to determine if32P leaches from the cement and into the blood, urine, or feces, and to identify unexpected adverse effects. Ourex vivoexperiments showed that cement with 4 mCi32P ml-1could be safely implanted in the vertebral body if the cement surface is at least 4 mm from the spinal cord in sheep and 5 mm from the spinal cord in humans.In vivo, a lateral retroperitoneal surgical approach, ventral to the transverse processes, was identified as easy to perform while allowing a safe distance to the spinal cord. The blood, urine, and feces of the sheep did not contain detectable levels of32P, and the sheep did not experience any neurologic or other adverse effects from the brachytherapy cement. These results demonstrate, on a preliminary level, the relative safety of this brachytherapy cement and support additional development and testing.

A strong positive correlation between the apparent ultimate strength and stiffness of bone tissue that can be expressed by a unified relationship has been observed for cortical bone in tension and low‐density cancellous bone in compression. For practical purposes, the existence of a relationship between strength and stiffness is significant in that bone stiffness can be measured in vivo using non‐invasive methods. It is generally accepted that bone strength is greater in compression than in tension whereas there is no substantial evidence that bone stiffness in compression is different from that in tension. This might suggest that compressive strength would relate to the stiffness, if at all, in a way that is different from tensile strength. In order to examine similarities and differences in the way strength is associated with stiffness between modes of loading and tissue type, we tested equine cortical bone and bovine cancellous bone in compression and examined these data together with previously reported data from compression testing of human cancellous bone as well as tensile testing of cortical bone from various sources. We have found for cortical bone that (i) the sensitivity of strength to stiffness is the same for tension and compression (p>0.75, ANCOVA), and (ii) the difference between the magnitudes of compressive and tensile strength for cortical bone is the result of an additive, rather than a multiplicative factor (52.1 MPa after adjusting to 1 microstrain/s, p<0.0001, ANOVA). High‐density bovine tibial cancellous bone, on the other hand, has a steeper slope for its compressive strength–stiffness relationship than that for cortical bone and human cancellous bone, resulting in a transitional relationship between compressive strength and stiffness for a range of bone types and densities. Based on the current results and previous work, it is suggested that the offset strength in the compressive strength–stiffness relationship may be a direct manifestation of the difference between the compressive and tensile strengths of the bone material that constitutes the building blocks of the bone structure. Deviation of high‐density cancellous bone compressive behavior from the other bone types and densities is attributed to stress distribution differences between the bone types. [ABSTRACT FROM AUTHOR]

Comprehensive treatment for vertebral metastatic lesions commonly involves vertebral augmentation (vertebroplasty or kyphoplasty) to relieve pain and stabilize the spine followed by multiple sessions of radiotherapy. We propose to combine vertebral augmentation and radiotherapy into a single treatment by adding 32 P, a β -emitting radionuclide, to bone cement, thereby enabling spinal brachytherapy to be performed without irradiating the spinal cord. The goal of this study was to address key dosimetry and safety questions prior to performing extensive animal studies. The 32 P was in the form of hydroxyapatite powder activated by neutron bombardment in a nuclear reactor. We performed ex vivo dosimetry experiments to establish criteria for safe placement of the cement within the sheep vertebral body. In an in vivo study, we treated three control ewes and three experimental ewes with brachytherapy cement containing 2.23-3.03 mCi 32 P ml -1 to identify the preferred surgical approach, to determine if 32 P leaches from the cement and into the blood, urine, or feces, and to identify unexpected adverse effects. Our ex vivo experiments showed that cement with 4 mCi 32 P ml -1 could be safely implanted in the vertebral body if the cement surface is at least 4 mm from the spinal cord in sheep and 5 mm from the spinal cord in humans. In vivo , a lateral retroperitoneal surgical approach, ventral to the transverse processes, was identified as easy to perform while allowing a safe distance to the spinal cord. The blood, urine, and feces of the sheep did not contain detectable levels of 32 P, and the sheep did not experience any neurologic or other adverse effects from the brachytherapy cement. These results demonstrate, on a preliminary level, the relative safety of this brachytherapy cement and support additional development and testing., (© 2022 Institute of Physics and Engineering in Medicine.)

The objective of this study was to determine the predictive value of tip-apex distance (TAD) and Parker's ratio for screw cutout after treatment of intertrochanteric hip fractures with a long cephalomedullary nail. A total of 97 patients with AO/OTA 31-A1-A3 intertrochanteric fractures and a minimum follow-up of 8 weeks were included. Increased Parker's ratio on the anteroposterior radiograph (OR = 1.386, p < .003) and lateral radiograph (OR = 1.138, p < .028) was significantly associated with screw cutout. In a multivariable regression analysis, only the Parker's anteroposterior ratio was significantly associated with risk of screw cutout (OR = 1.393, p = .004), but TAD (OR = 0.977, p = .764) and Parker's lateral ratio (OR 1.032, p = .710) were not independent predictors of cutout. The study concluded that Parker's anteroposterior ratio is the most helpful measurement in predicting screw cutout. (Journal of Surgical Orthopaedic Advances 28(2):115-120, 2019).