Evaluation of carbonate apatite blocks fabricated from dicalcium phosphate dihydrate blocks for reconstruction of rabbit femoral and tibial defects.

This study aimed to evaluate in vivo behavior of a carbonate apatite (CO3Ap) block fabricated by compositional transformation via a dissolution-precipitation reaction using a calcium hydrogen phosphate dihydrate [DCPD: CaHPO4·2H2O] block as a precursor. These blocks were used to reconstruct defects in the femur and tibia of rabbits, using sintered dense hydroxyapatite (HAp) blocks as the control. Both the CO3Ap and HAp blocks showed excellent tissue response and good osteoconductivity. HAp block maintained its structure even after 24 weeks of implantation, so no bone replacement of the implant was observed throughout the post-implantation period in either femoral or tibial bone defects. In contrast, CO3Ap was resorbed with increasing time after implantation and replaced with new bone. The CO3Ap block was resorbed approximately twice as fast at the metaphysis of the proximal tibia than at the epiphysis of the distal femur. The CO3Ap block was resorbed at an approximately linear change over time, with complete resorption was estimated by extrapolation of data at approximately 1-1.5 years. Hence, the CO3Ap block fabricated in this study has potential value as an ideal artificial bone substitute because of its resorption and subsequent replacement by bone.

Is a Stem Version on the Crosstable Lateral Radiograph Accurate in Total Hip Arthroplasty?

BACKGROUND: In contrast to the acetabular cup version (CV), stem version (SV) measurement on the crosstable lateral radiograph has not been validated. We, therefore, investigated: (1) the difference of SV on the crosstable lateral radiograph from that measured using computed tomography data and (2) the reliability of SV measurement on the crosstable lateral radiograph. METHODS: We examined the correlations of the crosstable-CV and crosstable-SV with true-CV (operative cup anteversion) and true-SV (neck version relative to the posterior condylar line) obtained using computed tomography data from 103 patients. We also produced the digital reconstructed crosstable lateral radiograph with adjusted hip flexion and rotation and defined SV on this image as the true-crosstable SV. RESULTS: Significant positive correlations were noted between the crosstable-CV and true-CV, with a correlation coefficient of 0.79. In contrast, the correlation between the crosstable-SV and true-SV was very low (r = 0.30), with significantly higher deviation from the true-SV values when compared with the crosstable-CV (standard deviation, 11.6° vs 6.5°, P < .001). The true-crosstable SV was correlated with true-SV (r = 0.81); however, the average difference was 23.5° ± 8.9°. CONCLUSION: Crosstable-SV differed from true-SV in the measurement plane and did not correlate well with the true-SV, suggesting the unreliability of its measurements. Therefore, the crosstable-SV is not recommended for clinical use.

Pelvic tilt and movement during total hip arthroplasty in the lateral decubitus position.

OBJECTIVES: Total hip arthroplasty (THA) is often performed in the lateral decubitus (lateral) position. In this position, the pelvis may have various degrees of tilt leading to implant malposition. We sought to quantify the pelvic tilt in lateral position and further pelvic movement during surgery. METHODS: In 95 cases with primary THA, three-dimensional pelvic tilts were quantified by superimposing images reconstructed from CT data onto antero-posterior radiographs taken in lateral position at set-up and after cup placement. Pelvises were fixed with a device compressing anterior superior iliac spines and sacrum. RESULTS: Various degrees of pelvic tilt occurred compared to the supine position; sagittal: -3.1° (-25.5° to 10.2°), axial: 3.9° (-8.4° to 17°), coronal: 0.9° (-11.9° to 13.2°). Absolute changes more than 5° were observed 43%, 47%, and 12% in the sagittal, axial, and coronal planes, respectively. The more preoperative posterior pelvic tilt resulted in the more change in the sagittal plane. Further pelvic movement of about 3° in three planes were observed ranging from -11° to 20° after cup placement. CONCLUSION: This study showed various pelvic tilt and movement during THA. As pelvic tilt directly alters the cup orientation, its changes should be well understood. Improved tools for positioning and holding the pelvis are required.

Optimal anterior femoral offset for functional range of motion in total hip arthroplasty--a computer simulation study.

PURPOSE: Compared to medial femoral offset (MFO), the role of anterior femoral offset (AFO) on range of motion (ROM) in total hip arthroplasty (THA) has not been fully examined. We therefore defined AFO as the anterior distance from the centre of the femoral head to the proximal femoral axis in the sagittal plane and determined the optimal AFO required for ROM needed for activities of daily living using a computer-simulated THA model. METHODS: Various AFOs were obtained by changing stem anteversion (stem-AV) and stem tilt in the sagittal plane (stem-tilt) using a CT-based simulation software. The required ROM was defined as: flexion ≥ 110°, internal rotation at 90° flexion (IR) ≥ 30°, external rotation (ER) ≥ 30°, and extension ≥ 30°, and we determined AFO and MFO to satisfy required ROM. RESULTS: AFO was positively correlated with stem-AV and anterior stem-tilt. MFO was negatively correlated with stem-AV and not influenced by stem-tilt. Flexion and IR increased with both increased AFO and MFO, whereas extension and ER decreased with increased AFO. A smoothing spline curve showed the optimal AFO and MFO for required ROM to be from 15 mm to 25 mm on average and more than 32.1 mm, respectively. CONCLUSIONS: This is the first study to show that AFO directly influenced ROM in THA. Optimal AFO as well as MFO should be reconstructed to achieve sufficient ROM.

Clinical and radiographic evaluation of total hip arthroplasties using porous tantalum modular acetabular components: 5-year follow-up of clinical trial.

OBJECTIVES: Porous tantalum is a biomaterial newly applied for artificial joints. We present here 5-years follow-up report of a multicenter clinical trial of total hip arthroplasties (THA) with porous tantalum modular acetabular component (modular PTC). METHODS: Study participants received 82 hips in 79 cases, with 61.2 months follow-up on average. Age at operation was 60.9 years. Clinical results were evaluated using Merle d'Aubigne Postel score. Presence of implant loosening, periacetabular radiolucency, osteolysis, and gap filling were examined for radiographic results. RESULTS: Merle d'Aubigne Postel score improved from 10.0 to 16.4 points. All PTC were radiographically stable, with no evidence of progressive radiolucencies. Average polyethylene wear rate was 0.004 mm/year, with no periacetabular osteolysis. Fifteen hips (18.3%) showed a gap >1 mm; however, all showed bone filling within 12 months. PTC with oversized reaming was significantly less likely to have a gap. No implant failure was noted related to modularity. Resulting survival rate of modular PTC was 100% at 5 years. CONCLUSIONS: Modular PTC showed excellent results at 5-years of follow-up. Some hips showed periacetabular gaps, which were filled with bone within 1 year. Further follow-up was needed to determine long-term efficacy.

Effects of estradiol, angiotensin-converting enzyme inhibitor and exercise training on exercise capacity and skeletal muscle in old female rats.

Physical fitness is closely related to cardiovascular health. We examined the effects of estradiol, angiotensin-converting enzyme inhibitor, exercise training, and their combination on exercise capacity as well as skeletal muscle fiber type and capillarity in old female rats. Twelve-month-old female Wistar-Kyoto rats were allocated to six groups: control (C), treatment with 17 beta-estradiol (0.025 mg/kg/dose, i.p. twice a week) (Est), perindopril (2 mg/kg/day) (Per), exercise training on a treadmill (15 m/min, 10 grade incline, 60 min/day, 5 days/week) (Exe), and combinations of a drug and exercise training (Exe+Est and Exe+Per). Following 6-month interventions, the rats were submitted to a stepwise exercise test on a treadmill. Moreover, fiber type and capillarity in both the soleus and gastrocnemius muscles were examined. Exercise capacity, capillary density, and the percentage of type I fiber significantly increased in Exe, Exe+Est, and Exe+Per compared to C. There were no significant differences in exercise capacity, capillary density, and percentage of type I fiber among C, Est, and Per. The combination of exercise training and perindopril further increased capillary density in both the soleus and gastrocnemius muscles, and the percentage of type I fiber in the gastrocnemius muscle compared to exercise training alone. We found that in old female rats, chronic treatment with estradiol or perindopril affected neither untrained exercise capacity nor exercise capacity acquired as a result of exercise training. However, we found that perindopril promotes adaptive changes of skeletal muscle in response to exercise such as increases in capillary density and the percentage of type I fiber.

Increased expression of urotensin II-related peptide and its receptor in kidney with hypertension or renal failure.

Urotensin II-related peptide (URP) is a novel vasoactive peptide that shares urotensin II receptor (UT) with urotensin II. In order to clarify possible changes of URP expression in hypertension and chronic renal failure (CRF), the expressions of URP and UT were studied by quantitative RT-PCR and immunohistochemistry in kidneys obtained from spontaneous hypertensive rats (SHR), Wistar-Kyoto rats (WKY), and WKY with CRF due to 5/6 nephrectomy. Expression levels of URP mRNA and UT mRNA were significantly higher in the kidneys obtained from SHR compared with age-matched WKY (at 5-16 and 16 weeks old, respectively). A dissection study of the kidney into three portions (inner medulla, outer medulla and cortex) showed that the expression levels of URP mRNA and UT mRNA were highest in the inner medulla and the outer medulla, respectively, in both SHR and WKY. The expression levels of URP and UT mRNAs were greatly elevated in the remnant kidneys of CRF rats at day 56 after nephrectomy, compared with sham-operated rats (about 6.5- and 11.9-fold, respectively). Immunohistochemistry showed that URP immunostaining was found mainly in the renal tubules, vascular smooth muscle cells and vascular endothelial cells. UT immunoreactivity was localized in the renal tubules and vascular endothelial cells. These findings suggest that the expressions of URP and UT mRNAs in the kidney are enhanced in hypertension and CRF, and that URP and its receptor have important pathophysiological roles in these diseases.

Combination of exercise and losartan enhances renoprotective and peripheral effects in spontaneously type 2 diabetes mellitus rats with nephropathy.

OBJECTIVES: We assessed the renal and peripheral effects of chronic exercise in a rat model of diabetic nephropathy and the benefits of combined exercise and losartan. METHODS: Heminephrectomized Goto-Kakizaki rats were divided into four groups: (i) no exercise (control); (ii) exercise with treadmill running; (iii) losartan; (iv) exercise plus losartan, and the rats were treated for 12 weeks. RESULTS: Losartan and exercise plus losartan significantly decreased systolic blood pressure (SBP). Exercise, exercise and losartan, and losartan blunted the increases in proteinuria. The index of glomerular sclerosis (IGS) and the relative interstitial volume of the renal cortex were significantly improved in the exercise, exercise and losartan, and losartan groups. The IGS, expressions of ED-1 and alpha-smooth muscle actin in the glomerulus were the lowest, and the number of Wilms' tumour was the highest in the exercise plus losartan group. The endurance, the proportion of type I fibre and capillarization in the extensor digitorum longus muscle were greater in the trained groups. CONCLUSION: These results suggest that both exercise and losartan have renoprotective effects, and the combination of exercise and losartan provided greater renoprotective effects than losartan alone, and may affect macrophage infiltration, mesangial activation, and podocyte loss in this model of diabetic nephropathy. It is also suggested that exercise has a specific renoprotective effect that is not related to SBP reduction, and can enhance endurance without renal complications.

Effects of antihypertensive drugs and exercise training on insulin sensitivity in spontaneously hypertensive rats.

We examined the effects of antihypertensive drugs, exercise training, and combinations thereof on insulin sensitivity (IS), and the association between this relation and sympathetic activity, muscle fiber composition, and capillary density in spontaneously hypertensive rats (SHR). Six-week-old male SHR were allocated to 7 groups: a control group (C), and groups treated with azelnidipine (Aze) (a calcium channel blocker), olmesartan (Olm) (an angiotensin II type 1 receptor blocker), exercise training (Exe), and combinations of drugs and exercise training (Aze+Exe, Olm+Exe, and Olm+Aze+Exe). At age 18 weeks, IS and sympathetic activity were evaluated by an euglycemic hyperinsulinemic glucose clamp technique and power spectral analysis of systolic blood pressure, respectively. After the experiments, capillary density and muscle fiber composition in soleus muscle were examined. Aze or Exe alone significantly increased IS associated with a significant reduction in sympathetic activity. Olm alone tended to increase IS with little change in sympathetic activity. Aze, Olm, or Exe significantly increased the capillary density and percentage of insulin-sensitive type I fiber. A combination of Aze and Exe or a combination of Olm and Exe tended to increase IS compared with each drug therapy alone. There were significant correlations between IS and sympathetic activity, capillary density, and the percentage of type I fiber in all the rats. We found that Aze improved IS more substantially compared with Olm in SHR. We also found that Aze, Olm, Exe, and combinations thereof improved IS, probably through the modulation of sympathetic activity or capillarity and muscle fiber type in skeletal muscles.

Synergistic effect of surface phosphorylation and micro-roughness on enhanced osseointegration ability of poly(ether ether ketone) in the rabbit tibia.

This study was aimed to investigate the osseointegration ability of poly(ether ether ketone) (PEEK) implants with modified surface roughness and/or surface chemistry. The roughened surface was prepared by a sandblast method, and the phosphate groups on the substrates were modified by a two-step chemical reaction. The in vitro osteogenic activity of rat mesenchymal stem cells (MSCs) on the developed substrates was assessed by measuring cell proliferation, alkaline phosphatase activity, osteocalcin expression, and bone-like nodule formation. Surface roughening alone did not improve MSC responses. However, phosphorylation of smooth substrates increased cell responses, which were further elevated in combination with surface roughening. Moreover, in a rabbit tibia implantation model, this combined surface modification significantly enhanced the bone-to-implant contact ratio and corresponding bone-to-implant bonding strength at 4 and 8 weeks post-implantation, whereas modification of surface roughness or surface chemistry alone did not. This study demonstrates that combination of surface roughness and chemical modification on PEEK significantly promotes cell responses and osseointegration ability in a synergistic manner both in vitro and in vivo. Therefore, this is a simple and promising technique for improving the poor osseointegration ability of PEEK-based orthopedic/dental implants.

Effects of angiotensin-converting enzyme inhibitor and exercise training on exercise capacity and skeletal muscle.

OBJECTIVE: Physical fitness is closely related with cardiovascular health. We examined the effects of angiotensin-converting enzyme inhibitor, exercise training and their combination on exercise capacity as well as skeletal muscle fiber type and capillarity in spontaneously hypertensive rats (SHR). METHODS: Seven-week-old male SHR were allocated to four groups: sedentary control (C), treatment with perindopril (3 mg/kg per day) (Per), exercise training on a treadmill (EX), and their combination (Per + EX). Following 8-week interventions, rats were submitted to a stepwise exercise test on a treadmill. After experiments, fiber type and capillarity in soleus muscle were examined. RESULTS: Exercise capacity significantly increased in Per compared with in C. Combination of exercise training and perindopril further increased exercise capacity compared with perindopril alone, whereas there was no significant difference in exercise capacity between EX and Per + EX. Capillary density increased similarly in Per and EX compared with in C. Combination of exercise training and perindopril further increased capillary density compared with exercise training alone. The percentage of type I fiber increased only in Per + EX. CONCLUSIONS: We found that in growing SHR, chronic treatment with perindopril enhances untrained exercise capacity, while it does not affect acquired exercise capacity as a result of exercise training. We also found that perindopril promotes adaptive changes of skeletal muscle in response to exercise such as increases in capillary density and percentage of type I fiber.

Fabrication of Carbonate Apatite Block through a Dissolution-Precipitation Reaction Using Calcium Hydrogen Phosphate Dihydrate Block as a Precursor.

Carbonate apatite (CO3Ap) block, which is a bone replacement used to repair defects, was fabricated through a dissolution-precipitation reaction using a calcium hydrogen phosphate dihydrate (DCPD) block as a precursor. When the DCPD block was immersed in NaHCO3 or Na2CO3 solution at 80 °C, DCPD converted to CO3Ap within 3 days. ß-Tricalcium phosphate was formed as an intermediate phase, and it was completely converted to CO3Ap within 2 weeks when the DCPD block was immersed in Na2CO3 solution. Although the crystal structures of the DCPD and CO3Ap blocks were different, the macroscopic structure was maintained during the compositional transformation through the dissolution-precipitation reaction. CO3Ap block fabricated in NaHCO3 or Na2CO3 solution contained 12.9 and 15.8 wt % carbonate, respectively. The diametral tensile strength of the CO3Ap block was 2 MPa, and the porosity was approximately 57% regardless of the carbonate solution. DCPD is a useful precursor for the fabrication of CO3Ap block.

Combination of exercise and enalapril enhances renoprotective and peripheral effects in rats with renal ablation.

BACKGROUND: It is suggested that appropriate chronic exercise (EX) may produce improvements of the physical strength in patients with chronic renal failure (CRF). Because acute exercise causes proteinuria and decreases the renal blood flow and glomerular filtration rate, it is necessary to consider the influence of EX on renal function. Therefore, we assessed the renal and peripheral effects of moderate to intense EX as well as the effects of the combination of EX and enalapril (ENA) in a rat model of CRF. METHODS: Male 5/6-nephrectomized Wistar-Kyoto rats were divided into six groups according to the following treatment: 1) no exercise (C); 2) ENA (2 mg/kg/day, subcutaneously); 3) moderate exercise with treadmill running (20 m/min for 60 min/day, 5 days/week) (EXm); 4) intense exercise with treadmill running (28 m/min for 60 min/day, 5 days/week) (EXi); 5) EXm+ENA; and 6) sham operation (S). The rats were then treated for 12 weeks. RESULTS: Both EX and ENA blocked the development of hypertension, blunted increases in proteinuria, reduced serum creatinine and blood urea nitrogen, and improved the index of glomerular sclerosis (IGS) and the relative interstitial volume of the renal cortex (RIV). Moreover, IGS and RIV in the EXm+ENA group were the lowest among all other nephrectomized groups. Furthermore, EXm+ENA enhanced capillarization as well as the proportion of type-I fiber in the soleus muscle. CONCLUSIONS: These results suggest that EX and ENA have renoprotective effects. The findings also suggest that EXm+ENA provided greater renoprotective effects than those of ENA alone, and that EXm+ENA had some additional peripheral effects without any complications in this rat model.

Mechanism behind augmentation in baroreflex sensitivity after acute exercise in spontaneously hypertensive rats.

A single bout of dynamic exercise increases baroreflex sensitivity (BRS) in spontaneously hypertensive rats (SHR). We examined whether change in hemodynamics (increases in blood pressure and heart rate) associated with dynamic exercise contribute to the post-exercise modulation of BRS. SHR aged 12 weeks were chronically instrumented with a carotid artery catheter and jugular vein catheter. They were then allocated to three groups submitted to 40 min of 1) running on a treadmill at 12 m/min (Run), 2) concomitant infusion of isoproterenol and a relatively high dose of phenylephrine (Iso+Phe(high)), or 3) concomitant infusion of isoproterenol and a relatively low dose of phenylephrine (Iso+Phe(low)). Arterial pressure and heart rate were continuously recorded throughout the experiments. BRS estimated by heart rate responses to phenylephrine injection and systolic blood pressure-low frequency power amplitude (SBP-LFamp) evaluated by power spectral analysis of SBP, a marker of sympathetic activity, were examined before and after running (Run group), or administration of drugs (Iso+Phe(high) or Iso+Phe(low) groups). BRS increased significantly from 1.4 to 1.9 bpm/mmHg after running, but not after administration of Iso+Phe(high) or Iso+Phe(low). Blood pressure and SBP-LFamp significantly decreased in each of the Run, Iso+Phe(high) and Iso+Phe(low) groups. These results suggest that hemodynamic change alone does not contribute to post-exercise modulation of BRS, while hemodynamic change or sympathetic activation during exercise contributes to post-exercise hypotension associated with a reduction of sympathetic activity.

[Renoprotective and antihypertensive effect of combination therapy with a low protein diet, long-term exercise and angiotensin II receptor antagonist in rats with renal ablation].

A low protein diet(LPD) has been prescribed to alleviate uremic symptoms, and to delay the aggravation of chronic renal failure(CRF). However, it has been suggested that LPD treatment causes malnutrition and attenuation of muscle power. On the other hand, it also has been suggested that appropriate long-term exercise training(EX) may lead to improvement of the physical fitness and quality of life (QOL) in patients with CRF. However, there is no definitive conclusion as to whether EX has any renal protective effect or not. We assessed the effects of combination therapy with LPD and EX. We also assessed the effects of a combination of these therapies and the angiotensin II receptor antagonist, olmesartan (OLS). Male Wistar Kyoto rats that were five-sixth-nephrectomized were divided into 6 groups; 1) normal-protein diet(NPD); 2) NPD and EX with treadmill running(1 h/day, 5 days/week for 12 weeks)(NPD + EX); 3) LPD; 4) LPD + EX; 5) LPD + EX with OLS( 10 mg/kg/day for 12 weeks) (LPD + EX + OLS); and 6) Sham-operated(S). Systolic blood pressure(SBP) in the NPD + EX, LPD + EX, LPD + EX + OLS, and S groups was significantly lower than in the NPD group. Moreover, SBP in the LPD + EX + OLS was significantly lower than in all the other groups. LPD, LPD + EX, and LPD + EX + OLS induced a significant decrease in UP, Scr and BUN compared with the NPD group. UP in the LPD + EX, LPD + EX + OLS, and S groups was significantly lower than in the LPD group. The index of glomerular sclerosis (IGS) and relative interstitial volume(RIV) in the NPD + EX, LPD, LPD + EX, LPD + EX + OLS, and S groups were significantly lower than the values in the NPD group. IGS and RIV in the LPD, LPD + EX, LPD + EX + OLS, and S groups were significantly lower than the values in the NPD + EX and LPD groups. Glomerular ED-1 positive cells in the LPD + EX, LPD + EX + OLS, and S groups was significantly fewer than in the NPD groups. These results indicate that LPD and EX have renoprotective effects, and suggest that the combination therapy with LPD and EX provides greater renoprotective effects than LPD alone. Moreover simultaneous treatment of OLS and LPD + EX provides greater antihypertensive and antiproteinuric effects than treatment with LPD + EX.

Quantification of pelvic tilt and rotation by width/height ratio of obturator foramina on anteroposterior radiographs.

OBJECTIVE: Compared to sagittal pelvic tilt, only a few studies have examined axial rotation on anteroposterior radiographs. We therefore quantified 3-D pelvic rotation using the width and height ratio of the obturator foramina under the various pelvic tilts. METHODS: Using CT reconstructions of 10 healthy pelvises, anterior pelvic planes (APPs) were rotated by 20° in 5° increments on the axial plane with various degrees of sagittal pelvic tilt. The correlation between the pelvic rotation angle and the width ratio (WR) in the axial plane and the height/width ratio (H/W) in the sagittal plane were examined. RESULTS: Axial pelvic rotation and WR showed a high linear correlation regardless of the sagittal tilt, with the correlation coefficient ranging from 0.93 to 0.98 in males and 0.87 to 0.95 in females. The angle that resulted in a WR of 1:2 was approximately 13° in males and 18° in females. H/W also showed a linear regression with sagittal tilt. Axial rotation was determined by the following equation incorporating pelvic tilts; axial rotation (male:female) = (19.9:24.2) + (2.1:3.6) × Hright/Wright + (0.9:1.5) × Hleft/Wleft - (23.2:25.1) × WR. CONCLUSIONS: Pelvic tilt and rotation could be quantified by the equation using width and height ratios of the obturator foramina on a plain anteroposterior radiograph. Width and height ratios of the obturator foramina proved to be useful parameters in clinical practice for understanding pelvic rotation.

Late Anterior Dislocation Due to Posterior Pelvic Tilt in Total Hip Arthroplasty.

BACKGROUND: Excessive pelvic tilt may be one of the factors leading to instability in total hip arthroplasty (THA), even when the acetabular cup is placed properly. To our knowledge, only a few studies have described late anterior dislocation due to posterior pelvic tilt. We present 3 cases with late anterior dislocations possibly due to posterior pelvic tilt. CASES PRESENTATIONS: Case-1: An 84-years-old woman fell and presented with an anterior dislocation 12-years after THA. Her pelvis had tilted to approximately 30° posteriorly in a supine position. After conservative treatment, she presented with 10 recurrent anterior dislocations. She had thoracolumbar kyphosis due to multiple compression fractures. Revision with anterior placement of an elevated liner and a 32-mm head corrected the dislocation, and no further dislocations occurred. Case-2: A 78-years-old woman fell and presented with an anterior dislocation 4-years after THA. Her posterior pelvic tilt had increased 23° due to a lumbar compression fracture. Revision by decreasing the cup anteversion was performed, but recurrent posterior dislocations occurred. Owing to her worsened general condition, further treatment was abandoned. Case-3: A 79-years-old woman twisted her body and presented an anterior dislocation 3-years after THA. After manual reduction and conservative treatment, the dislocation recurred. Her posterior pelvic tilt had increased 16°. CONCLUSION: Although minor trauma triggered the anterior instability in these patients, the underlying pathomechanism existed in the progressive pelvic posterior tilt due to thoracolumbar kyphosis. As longer life expectancy as well as implant survivorship is predicted, attention must be paid to the change of pelvic tilt in elderly patients.

High prevalence of cam deformity in dysplastic hips: A three-dimensional CT study.

Cam deformity could lead to suboptimal articulation by causing secondary femoroacetabular impingement after periacetabular osteotomy; however, the inherent femoral head-neck morphology in dysplastic hips and the effect of an additional osteoarthritic deformity have not been well described. We compared femoral head-neck morphology using three-dimensional imaging of normal and dysplastic hips in pre/early (Tönnis grade 0 and 1) and advanced stage osteoarthritis (Tönnis grade 2). Using computed tomography, we measured the circumferential α-angle and head-neck offset ratio in 68 dysplastic hips and 24 normal hips. Locations of the head-neck junction were represented by the clock position. In the pre/early group, the α-angle was significantly larger at the anterosuperior and inferior aspects (1, 2, and 5-7 o'clock) and head-neck offset ratio was smaller at the anterosuperior aspect (2 o'clock) than in the control group. The α-angle was significantly larger at the anterior aspects (1-4 o'clock) in the advanced group than in the pre/early group. The maximum α-angle was most commonly found at 2 o'clock (60%, 41/68 hips) in dysplastic hips. The prevalence of cam deformity (maximum α-angle >55°) was 4.2% (1/24 hips) in the control group, 22% (11/50 hips) in the pre/early group, and 50% (9/18 hips) in the advanced group. Cam deformity, inherent in the pre/early group, was found with relatively high frequency. The higher prevalence in the advanced group reflected degeneration-modified changes. When performing periacetabular osteotomy, preoperative radiographic assessments should include the femoral head-neck junction to prevent secondary femoroacetabular impingement, especially in patients with advanced stage osteoarthritis. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1613-1619, 2016.

Bone bonding strength of diamond-structured porous titanium-alloy implants manufactured using the electron beam-melting technique.

The present study examined the bone bonding strength of diamond-structured porous titanium-alloy (Porous-Ti-alloy) manufactured using the electron beam-melting technique in comparison with fiber mesh-coated or rough-surfaced implants. Cylindrical implants with four different pore sizes (500, 640, 800, and 1000µm) of Porous-Ti-alloy, titanium fiber mesh (FM), and surfaces roughened by titanium arc spray (Ti-spray) were implanted into the distal femur of rabbits. Bone bonding strength and histological bone ingrowth were evaluated at 4 and 12weeks after implantation. The bone bonding strength of Porous-Ti-alloy implants (640µm pore size) increased over time from 541.4N at 4weeks to 704.6N at 12weeks and was comparable to that of FM and Ti-spray implants at both weeks. No breakage of the porous structure after mechanical testing was found with Porous-Ti-alloy implants. Histological bone ingrowth that increased with implantation time occurred along the inner structure of Porous-Ti-alloy implants. There was no difference in bone ingrowth in Porous-Ti-alloy implants with pore sizes among 500, 640, and 800µm; however, less bone ingrowth was observed with the 1000µm pore size. These results indicated Porous-Ti-alloy implants with pore size under 800µm provided biologically active and mechanically stable surface for implant fixation to bone, and had potential advantages for weight bearing orthopedic implants such as acetabular cups.

Effects of exercise and beta-blocker on blood pressure and baroreflexes in spontaneously hypertensive rats.

BACKGROUND: Exercise training or beta-blocker decreases high blood pressure (BP) and improves abnormal baroreflex function associated with hypertension. This study was undertaken to examine whether the effects of exercise training are additive to beta-blocker in spontaneously hypertensive rats (SHR). METHODS: At 5 weeks of age, SHR were allocated to four groups: sedentary control, exercise training, treatment with moderate dose of bisoprolol, and their combination. Systolic BP was monitored by the tail-cuff method under restrained conditions. Sigmoidal mean arterial pressure (MAP)-heart rate (HR) reflex curves were obtained in rats at 17 weeks of age under quiet conditions before and after atenolol to ensure sympathetic blockade and to determine the vagal component of gain. After studying baroreflex function, intrinsic HR was obtained by additional administration of atropine. RESULTS: Before atenolol, both exercise training alone and bisoprolol alone lowered resting MAP and HR, and decreased upper plateau (maximal tachycardia) and lower plateau (maximal bradycardia), resulting in decreased sympathetic component of HR range (upper plateau - intrinsic HR) and increased vagal component of HR range (intrinsic HR - lower plateau). After atenolol, both exercise training alone and bisoprolol alone increased the gain of vagal component. Exercise training had no additive effect on any parameters to bisoprolol except for systolic BP and HR measured by the tail-cuff method. CONCLUSIONS: Exercise training and bisoprolol have similar effects concerning resting hemodynamics and baroreflex function in SHR. Although additive effects of exercise training to bisoprolol are not evident under quiet, nonstressful conditions, some additive effects may be obtained under stress such as restrain.