Disorders of bone integrity carry a high global disease burden, frequently requiring intervention, but there is a paucity of methods capable of noninvasive real-time assessment. Here we show that miniaturized handheld near-infrared spectroscopy (NIRS) scans, operated via a smartphone, can assess structural human bone properties in under three seconds. A hand-held NIR spectrometer was used to scan bone samples from 20 patients and predict: bone volume fraction (BV/TV); and trabecular (Tb) and cortical (Ct) thickness (Th), porosity (Po), and spacing (Sp).Aims
Methods
Near infrared light between the wavelengths of 700 and 950 nanometers has a relatively low absorption in tissue, and light of these wavelengths is able to penetrate several centimetres into tissue. Absorption of light is primarily due to hemoglobin. The absorption spectra for oxy-hemoglobin and deoxy-hemoglobin are different, and therefore comparison of light absorption at different wavelengths allows an assessment of the relative concentrations of these two chromophores. Light penetrates bone as well as soft-tissue, and
Purpose: Several variables related to tourniquet (TQ) inflation contribute to ischemic muscle injury. Among these the duration of ischemia has been identified as a primary factor. The purposes of this study were to investigate the following during and after TQ-induced ischemia during orthopedic trauma surgery:. muscle oxygenation changes measured by
Purpose: Near-infrared spectroscopy (NIRS) detects changes in chromophore concentrations of oxygenated (O2Hb) and deoxygenated hemoglobin (HHb) in target tissues approximately 2 to 3 cm below the skin. The main purpose of this study was to non-invasively measure skeletal muscle oxygenation in the leg during and after tourniquet (TQ)-induced ischemia using continuous wave NIRS. Secondarily, we aimed to assess the sensitivity, specificity, and reliability of this optical technique for detection and continuous monitoring of changes in muscle oxygenation and hemodynamics during TQ-induced ischemia throughout orthopedic surgery. Method: Consented patients aged 19–69 (n=21) with unilateral ankle fracture requiring emergency or elective surgery at our institution were recruited. All patients underwent standard general anesthetic. A pair of NIRS probes was fixed over the midpoint of the tibialis anterior muscle (TA) of both the fractured and healthy legs. A thigh TQ was applied to the injured leg and inflated to 300 mmHg. Using the NIRS apparatus coupled to a laptop with data acquisition software, changes in O2Hb, HHb, and total hemoglobin (tHb) levels in the TAs of both legs were measured at 10 Hz before and during TQ inflation, and after release until values returned to baseline. In each surgery the TQ was released when arterial obstruction was no longer required by the clinical team. Data are reported as mean±SD. Results: Changes in O2Hb, HHb, and tHb were successfully collected, stored and transmitted for graphic display in all subjects. TQ time (ischemia interval) varied among subjects, from 1245 s to 4431 s (2753±854). NIRS measured a progressive increase in HHb (2.6±2 μmol/L) during the first minute of TQ inflation and a sharp increase in O2Hb (23.3±12 μmol/L) during the first minute of leg muscle reperfusion (after deflation). Following TQ inflation a progressive increase in HHb (24.2±10.3 μmol/L) with a concomitant decrease in O2Hb (mean – 24.4±8 μmol/L) in the under-TQ TA were consistent across subjects. These changes in ΔHHb and ΔO2Hb began to reverse immediately after TQ deflation. Significant correlations were observed between ischemia interval and, respectively, oxygenation recovery time (r2=0.84) and changes of deoxygenated hemoglobin (r2=0.57). Conclusion: We demonstrated that, following TQ inflation and deflation respectively, NIRS can sensitively monitor muscle deoxygenation and reoxygenation. Consistent patterns of ΔHHb and ΔO2Hb occurred during TQ-induced ischemia in all subjects. These data confirm that
Introduction: In the evaluation of various treatments that may have an effect on bone, there are certain inherent difficulties in selecting an appropriate outcome measure to determine whether a specific treatment is efficacious. This is particularly true for clinical studies. Methods: Using Pubmed, a service of the U.S. National Library of Medicine that searches MEDLINE and other life science journals for citations of biomedical articles, a review of the current instruments used for outcome measures relating to osteonecrosis and bone blood flow was conducted. Abstracts from previous ARCO meetings were also reviewed. Results: For the treatment of osteonecrosis, most outcome measures have focused on pain relief, surgery or need for surgery, disease progression (advancing stage), and change in lesion size. The first three options may be influenced by investigator bias and knowledge/experience. The last option may also be influenced by the technique used. Imaging techniques continue to gain in sophistication. Gd-enhanced MRI can be used to assess perfusion of the diseased tissue. Doppler ultrasonography has also been used to estimate blood flow noninvasively.
Introduction: Studies have shown