Jung Hwa Hong

Determining optimal sleep position in patients with positional sleep-disordered breathing using response surface analysis.

A lateral position (LP) during sleep is effective in reducing sleep disorder symptoms in mild or moderate sleep apnea patients. However, the effect of head and shoulder posture in LP on reducing sleep disorders has not been reported. In this study, effective sleeping positions and a combination of sleep position determinants were evaluated with respect to their ability to reduce snoring and apnea. The positions evaluated included the following: cervical vertebrae support with head tilting (CVS‐HT), scapula support (SS), and LP. A central composite design was applied for response surface analysis (RSA). Sixteen patients with mild or moderate positional sleep apnea and snoring who underwent polysomnography for two nights were evaluated. Based on an estimated RSA equation, LP (with a rotation of at least 30°) had the most dominant effect [P = 0.0057 for snoring rate, P = 0.0319 for apnea–hypopnea index (AHI)]. In addition, the LP was found to interact with CVS‐HT (P = 0.0423) for snoring rate and CVS‐HT (P = 0.0310) and SS (P = 0.0265) for AHI. The optimal sleep position reduced mild snoring by more than 80% (i.e. snoring rate in the supine position was <20%) and the snoring rate was approximately zero with a 40° rotation. To achieve at least 80% reduction of AHI, LP and SS should be >30° and/or 20 mm respectively. To determine an effective sleep position, CVS‐HT and SS, as well as the degree of the LP, should be concurrently considered in patients with positional sleep apnea or snoring.

Microscopic Multi-Directional Mechanical Properties of Human Femoral Cancellous Bone Tissue

Multi-directional mechanical properties of human cancellous bone tissue were never measured using a compressive test with microscopic cubic specimens. In this study, a small scale compressive testing machine with nano meter resolution and a measurement system for Poisson’s ratio with sub-nano meter resolution were developed to measure accurate microscopic mechanical properties of human CBT. The measured mean longitudinal (E1), postero-anterior (E2), and lateromedial (E3) elastic moduli were 3.47 GPa (S.D. ±0.41), 2.57 GPa (S.D. ±0.28), and 2.54 GPa (S.D. ±0.22), respectively. ANOVA showed that the longitudinal elastic modulus (E1) was significantly (p < 0.01) greater than the postero-anterior (E2) and latero-medial (E3) elastic moduli. For Poisson’s ratios, ν12 was significantly (p <0.01) higher than ν23 and ν31.

Development of Pore Pressure Measurement System in Lacunocanalicular Network of Trabeculae Using MEMS Based Micro-Pressure Transducer

Experimental measurement of pore pressure generation in lacunocanalicular network of trabeculae is never measured, although the characteristics could be important for bone remodeling. In this study, the pore pressure generation in micro-trabecular specimens within the elastic range was measured in vitro using a specially designed micro-experimental setup and a MEMS based micro-pressure transducer. Then, a quasi-static loading (9㎛/min) was applied up to the strain of 0.4 % with measuring pore pressure generations in the undrained and drained conditions. 49.2 ± 4.45 KPa of pore pressure generation at the 0.4% strain was found in the undrained condition. In contrast, no pore pressure generation was measured in the drained condition. The result could let us know the amount of a possible maximum pore pressure generation in lacunocanalicular network of trabeculae within the elastic range.

Measurment of Strain Generated Potential Near Bone and Implant Interface for Assessment of Osseointegration

In this study, a minimally invasive assessment using bone strain generated potential (SGP) was developed to examine the amount of osseointegration (OI) at bone-implant interface. SGP is generated by interstitial fluid flow in porous bone structure. Four experimental white New Zealand rabbits underwent pure titanium implant insertion surgery to tibia after amputation. After surgery, two animals were kept in small cages with minimal movement (Group 1). In contrast, the other rabbits were kept in a large cage that was large enough for jumping and walking (Group 2). At the end of the 5 weeks, all experimental animals were euthanized and the amputated tibia-implants were harvested. Then, a quasi-static force was applied to a bone site near the bone-implant interface for each tibia-implant specimen. Also, SGPs were measured near the interface using needle or probe electrodes. After the measurements, digital radiographs were taken to check the amount of OI for the interfaces. Full OI was observed for animals in Group 1. However, incomplete OI was found for animals in Group 2. Also, significant difference was found for mean SGP values between Group 1 and 2. The results could imply that SGP could be used as a minimally invasive assessment method to check the OI at the bone-implant interface.

Age at Diagnosis and Mass Size as Clinical Indications for Hysteroscopic Mass Excision

adenomyosis, 3 had fibroids and 5 had endometriosis. In the 28 patients with pain and bleeding, 11 had adenomyosis, 11 had fibroids and 3 had endometriosis. In the new onset pain group, 9 of the 16 patients had postablative fibrosis and scarring noted on the pathology report. In the pain and bleeding group there were 7 reports of these changes. Conclusion: Bleeding was the most common reason for Novasure failure. Although one quarter of the women who went on to hysterectomy had some component of new onset pain the majority had some additional pathology consistent with development of pain. In only 3 patients (0.1%) with new onset pain was there no obvious pathology. The finding of postablative scarring and fibrosis was not found universally in the patients with new onset pain, nor was it consistently noted in those patients with a bleeding component, which makes it difficult to attribute it as a consistent or common cause of the pain.

Microscopic Multi-Directional Permeability Coefficient of Human Lumbar Vertebral Cancellous Bone Tissue

The mechanical performance of cancellous bone is characterized using experimental measure of parameters (elastic moduli, permeability, etc.) which apply poroelasticity theory. Poroelastic investigations of bone are being extended to investigations of micro-mechanisms of remodeling processes and transport of metabolic product in bone. To understand physiological and pathological behavior of human skeletal system, the accurate measurement of biomechanical properties for bone is the one of important works. Particularly, the microscopic measurement is very important since the biomechanical behavior at the small scale of bone could be closely related to the remodeling of bone. But microscopic measurement of permeability coefficient which is one of important parameter of poroelasticity theory was never measured. In this study, a small scale permeability testing machine was developed to measure accurate coefficient of microscopic specimen permeability. Total of twenty one cylindrical cancellous specimens with a diameter of 500 from seven fresh male and female lumbar vertebrae (14, 39, 59, 61, 69, 75, and 77 years) were fabricated using a micro-milling machine having a resolution of 10 . To determine the directional permeability, bone coordinate was set to be x1 (longitudinal axis) and others were set as x2 (posteroanterior axis) and x3 (latero-medial axis). The measured mean permeability (± SD) values of each direction from x1 to x3 were 9 5.56 10− × (S.D. ± 10 7.10 10− × ), 9 6.66 10− × (S.D. ± 10 6.56 10− × ), and 9 7.04 10− × (S.D. ± 10 8.47 10− × ) m2/Pa/sec, respectively. Mean value in the x1 direction of specimens were the smallest (p<0.01) in comparison to x2 and x3 directions.

Prediction of Intraosseous Pressure Behavior to Understand Strain Generated Potential near Osseointegrated Bone and Implant Composite

Osseointegration (OI) could be described as the modality for stable fixation of titanium implant to bone structure. The OI has become a realized phenomenon of importance in the dental and rehabilitation sciences since recently developed dentures and artificial limbs are directly attached to human skeleton by using osseointegrated implants. Previously, a study showed that bone strain generated potential (SGP) that is an electrical potential and considered to be generated by fluid flow in bone could be used as a parameter to examine the amount of OI on implant-bone interface. SGP generation is known to require intraosseous fluid flow related with generations of pore pressure gradient in bone. Therefore, SGP would interact with properties determining interstitial fluid flow characteristics such as viscosity, velocity, flow path directions, and interstitial fluid flow boundary conditions. Since interstitial fluid flow characteristics in bone are governed by pore pressure gradient, it could be possible to predict SGP indirectly through the prediction of pore pressure generation in bone. The aim of this study is to predict the distribution of pore pressure in OI bone-implant composite representing a completely osseointegrated rabbit tibia-titanium implant composite. The theoretical background of this prediction is based on the poroelasticity of 2-phase material that grounds on fluid flow and behavior of cortical bone material. In this study, we constructed a finite element (FE) model of the composite from images of micro-CT scanning. In the next step, we examined analysis of the FE model about pore pressure by using ABAQUS. In this analysis, the constitutive behavior was externally computed by utilizing a user subroutine. The results showed the different spatial distributions of pore pressure in the composite. The magnitudes of pore pressure were found to be significantly increased when the position was approached for the interface of implant-bone. Further analytical study is required to fully understand relationships between SGP and pore pressure distributions in OI bone-implant composite materials.

Rate-Dependent Strain Generated Potentials in Ossointegrated Implant-Bone Composite

Osseointegration (OI) could be described as the modality for stable fixation of titanium implant to bone structure. The OI has become a realized phenomenon of importance in the dental and rehabilitation sciences since recently developed dentures and artificial limbs are directly attached to human skeleton by using osseointegrated (OI) implants. Previously, a study showed that bone strain generated potential (SGP) that is an electrical potential and considered to be generated by fluid flow in bone could be used as a parameter to examine the amount of OI on bone-implant interface. Since no study was performed to understand effects of loading rate changes on behavior of SGP for the bone-implant composite, rate dependent behavior of SGP was investigated in this study. Four different displacement rates, 100, 200, 500, and 1000 mm per minute were applied to the bone-implant composites. During the compression tests, SGPs were also measured. Magnitude of SGP was found to be significantly increased as the rate increased for OI bone-implant composite. In contrast, the time duration of SGP was decreased as the rate increased. These results could imply that the temporal SGP behavior of bone-implant composite is significantly affected by the loading rate.

Fluid Pressure Measurement in Lacunocanalicular Network of Trabeculae Using MEMS Based Micro-Pressure Transducer

The intraosseous pressure generation and fluid flow in lacunocanalicular network of trabeculae could be important to the remodeling process of cancellous bone. Due to the technical difficulty, experimental information about the amount of intraosseous pressure generation in lacunocanalicular network of trabeculae is never measured. In this study, the maximum intraosseous pressure generation in micro-trabecular specimens within the elastic range was measured in vitro using a specially designed micro-experimental setup representing the most restrictive fluid flow boundaries around microscopic bovine vertebral trabecular specimens. Then, a quasi-static loading (9mum/min) was applied up to the strain of 0.4% with measuring intraosseous pressure generations in the undrained and drained conditions. 49.2plusmn4.45 KPa of intraosseous pressure generation at the 0.4% strain was found in the undrained condition. In contrast, no intraosseous pressure generation was measured in the drained condition. The result could let us know the amount of a possible maximum intraosseous pressure generation in lacunocanalicular network of trabeculae within the elastic range