Awareness of chronic obstructive pulmonary disease (COPD) among the general population in Aseer Region, Kingdom of Saudi Arabia (KSA)

Background

Chronic obstructive pulmonary disease (COPD) is a common but preventable disease and has a prevalence of 5%-14% in the general population. It is characterized by airflow limitation and persistent respiratory symptoms. In this survey, we aimed to assess the awareness of COPD among the general population in the Aseer Region of the Kingdom of Saudi Arabia (KSA).

Method

This was an observational, cross-sectional study in which predesigned electronic questionnaires were distributed to 504 randomly selected community personnel utilizing phone services. The collected data were analyzed using the IBM SPSS Statistics software, version 24 for Windows (IBM Corp., Armonk, NY).

Results

Participants were asked 11 questions with yes-or-no answers based on awareness and symptoms of COPD: 35.5% of participants had heard about the COPD as a term and 72% had no detailed information about COPD. Only 3.5% of participants had relatives with COPD. During the survey on COPD symptoms, 31% of participants chose shortness of breath and the rest chose cough (20%), sputum production (15%), wheezing (14%), and chest pain (19%). Almost two-third of the participants had no idea about COPD symptoms. For the most disease knowledge, majority of the study participants had very poor knowledge about the disease that was evident in the 22 questions intended to assess this domain. Social media sites ranked as the most popular source of information on COPD among the study participants.

Conclusion

Awareness about COPD among the general population in the Aseer Region in KSA is poor. It is advisable to carry out programs to increase their level of awareness.

An Overview of Clinical Manifestations of Dermatological Disorders in Intensive Care Units: What Should Intensivists Be Aware of?

Acute skin failure is rarely the primary diagnosis that necessitates admission to an intensive care unit. Dermatological manifestations in critically ill patients, on the other hand, are relatively common and can be used to make a key diagnosis of an adverse drug reaction or an underlying systemic illness, or they may be caused by factors related to a prolonged stay or invasive procedures. In intensive care units, their classification is based on the aetiopathogenesis of the cutaneous lesion and, in the meantime, distinguishes critical patients. When evaluating dermatological manifestations, several factors must be considered: onset, morphology, distribution, and associated symptoms and signs. This review depicts dermatological signs in critical patients in order to lay out better recognition.

COVID-19 Psychological Impact on Health Care Workers in Saudi Arabia

OBJECTIVE

Little is known about the impact of Coronavirus (COVID-19) among the health care workers in Saudi Arabia. Therefore, the present study aimed to assess the psychological impact of COVID-19 among the health care workers.

METHODS

A cross-sectional survey was conducted from May till mid-July among 389 health care workers from government and private hospitals in Saudi Arabia. Data was collected using a pre-structured online questionnaire that measured adverse psychological outcomes, including the Patient Health Questionnaire-9 (PHQ-9) scale and the Generalized Anxiety Disorder 7-item (GAD-7) scale. The Pearson chi-square test was used to assess the distribution of depression and anxiety among health care workers.

RESULTS

A high level of anxiety was recorded among the health care workers, and 69.3% of health care workers below the age of 40 were found to have depression. There was a significant increase in depression among staff with chronic health problems (72.1% vs. 61.9%; p = 0.048). High anxiety levels were detected among young staff compared to others (68.7% vs. 43.8%; p = 0.001). Moreover, 82.1% of the female staff were anxious, as compared to 55.6% of the males (p = 0.001).

CONCLUSIONS

We found increased prevalence of adverse psychological outcomes among the health care workers in Saudi Arabia during the outbreak of COVID-19. Therefore, there is a need for proper screening and development of corresponding preventive measures to decrease the adverse psychological outcomes.

Preoperative mannitol infusion improves perioperative cerebral oxygen saturation and enhances postoperative recovery after laparoscopic cholecystectomy

Objectives:

To test the effect of preoperative mannitol infusion on perioperative decreased cerebral oxygen saturation (rSO₂) during laparoscopic cholecystectomy.

Methods:

Forty patients scheduled for laparoscopic cholecystectomy were enrolled in this study conducted at Dammam Hospital of the University, Dammam, Kingdom of Saudi Arabia from December 2013 to June 2014. Patients received either 0.5 g/kg of 20% intravenous mannitol infusion over 10 minutes before induction of anesthesia (group M), or an equal volume of normal saline instead (group C). Primary outcome variable was rSO₂. Other variables included extubation time, clinical assessment of consciousness recovery using the Modified Observer’s Assessment of Alertness/Sedation Scale (OAA/S), and the mini-mental state examination (MMSE) for cognitive evaluation.

Results:

Anesthesia induction increased rSO₂ in both groups. Pneumoperitoneum decreased rSO₂ in group C, but not in group M. This drop in rSO₂ in the group C reached its maximum 30 minutes after extubation, and was significantly less than the preinduction value. Time to extubation in group M was significantly shorter compared to group C (p=0.007). The OAAS in group M at 10 min after extubation was significantly higher compared to group C. No differences were found between the 2 groups in cognitive function as measured by MMSE score.

Conclusion:

Preoperative mannitol infusion maintains perioperative rSO₂ during laparoscopic cholecystectomy and shortens extubation time with earlier resurgence of OAAS.

Multiple levels paravertebral block versus morphine patient-controlled analgesia for postoperative analgesia following breast cancer surgery with unilateral lumpectomy, and axillary lymph nodes dissection

BACKGROUND

Postoperative pain after breast cancer surgery is not uncommon. Narcotic based analgesia is commonly used for postoperative pain management. However, the side-effects and complications of systemic narcotics is a significant disadvantage. Different locoregional anesthetic techniques have been tried including, single and multiple levels paravertebral block (PVB), which seems to have a significant reduction in immediate postoperative pain with fewer side-effects. The aim of this study was to compare unilateral multiple level PVB versus morphine patient-controlled analgesia (PCA) for pain relief after breast cancer surgery with unilateral lumpectomy and axillary lymph nodes dissection.

MATERIALS AND METHODS

Forty patients scheduled for breast cancer surgery were randomized to receive either preoperative unilateral multiple injections PVB at five thoracic dermatomes (group P, 20 patients) or postoperative intravenous PCA with morphine (group M, 20 patients) for postoperative pain control. Numerical pain scale, mean arterial pressure, heart rate, Time to first analgesic demand, 24-h morphine consumption side-effects and length of hospital stay were recorded.

RESULTS

PVB resulted in a significantly more postoperative analgesia, maintained hemodynamic, more significant reduction in nausea and vomiting, and shorter hospital stay compared with PCA patients.

CONCLUSION

Multiple levels PVB is an effective regional anesthetic technique for postoperative pain management, it provides superior analgesia with less narcotics consumption, and fewer side-effects compared with PCA morphine for patients with breast cancer who undergo unilateral lumpectomy, with axillary lymph nodes dissection.

The use of laryngeal mask airway during transesophageal echocardiography in pediatric patients

Background:

Transesophageal echocardiography (TEE) in the cardiac lab is usually performed in pediatric patients under general anesthesia with an endotracheal intubation (ET). This study was performed to investigate the safety and efficacy of using the laryngeal mask airway (LMA) as an alternative to ET to maintain pediatric airway during the general anesthesia for TEE.

Materials and Methods:

A total of 50 pediatric patients undergoing TEE in the cardiac lab were randomized to have their airway maintained during the procedure with either LMA (LMA group) or ET (ET group). Hemodynamic, respiratory parameters, time to extubation, recovery time, the incidence of complication and operator satisfaction were compared between the two groups.

Results:

There were no differences between both groups in hemodynamic and respiratory parameters. Laryngeal spasm was reported in one patient in the LMA group and two patients in the ET group. TEE operators were equally satisfied with the procedure in groups. The time to extubation was shorter in the LMA group (P < 0.01). The mean recovery time was also significantly shorter in the LMA than in the ET group (44 ± 8 min and 59 ± 11 min, respectively; P < 0.001).

Conclusion:

The LMA is safe and effective in securing the airway of children undergoing diagnostic TEE.

Isometric force dynamometer is superior to bromage score in prediction of patients' ambulation after spinal anesthesia in ambulatory surgeries

BACKGROUND

The aim of our study was to use a quantitative measure of muscle strength to identify the muscle power at which the patient can safely ambulate unassisted after spinal anesthesia.

METHODS

Twenty ASA physical status I and II patients undergoing elective perineal or lower abdominal surgery under spinal anesthesia were enrolled in the study. Spinal anesthesia was conducted using 10 mg heavy bupivacaine. The regression of motor block was assessed both qualitatively using the Bromage score and quantitatively by measuring the isometric contraction of the knee, hip, and ankle flexors every 15 minutes until the patient was able to ambulate unassisted.

RESULTS

The rate of regression of the Bromage score was faster than regression of the isometric forces at all tested joints. As the median Bromage score reached 0 (no motor blockade), the mean±SD motor power recoveries at the knee, hip, and ankle were 28.2%±16%, 45.5%±24%, and 56.3%±28 %, respectively, and only 6 of 20 patients (30%, 95% confidence interval 10%-53%) were able to walk unassisted. After 75 minutes passed, 90% of the patients (95% confidence interval 56%-99%) were able to walk unassisted with mean motor power recovery of 63.6%±20%, 82.1%±27%, and 90.2%±24% at the knee, hip, and ankle, respectively. The area under the receiver operating characteristic curves was significantly higher with isometric contraction at different joints than the Bromage score (P<0.001). In addition, isometric contraction at different joints was effective in predicting the patients' ability to walk unassisted after subarachnoid block with prediction probabilities of 0.901, 0.948, and 0.958 for the knee, hip, and ankle, respectively, as compared with 0.752 for the Bromage score (P<0.001).

CONCLUSION

Quantitative measurement of the degree of recovery of the motor power of the knee, hip, or ankle flexors is more accurate and superior to the qualitative Bromage score, as a predictor of the patient's ability to safely ambulate after spinal anesthesia. This may be recommended when assessing motor block when small-dose anesthetic solutions are used.

Is sealing cuff pressure, easy, reliable and safe technique for endotracheal tube cuff inflation?: A comparative study

OBJECTIVE

To compare the three common methods of endotracheal tube cuff inflation (sealing pressure, precise standard pressure or finger estimation) regarding the effective tracheal seal and the incidence of post-intubation airway complications.

METHODS

Seventy-five adult patients scheduled for N(2) O free general anesthesia were enrolled in this study. After induction of anesthesia, endotracheal tubes size 7.5 mm for female and 8.0 mm for male were used. Patients were randomly assigned into one of three groups. Control group (n=25), the cuff was inflated to a pressure of 25 cm H(2)O; sealing group (n=25), the cuff was inflated to prevent air leaks at airway pressure of 20 cm H(2)O and finger group (n=25), the cuff was inflated using finger estimation. Tracheal leaks, incidence of sore throat, hoarseness and dysphagia were tested.

RESULTS

Although cuff pressure was significantly low in the sealing group compared to the control group (P<0.001), the incidence of sore throat was similar in both groups. On the other hand, cuff pressure as well as the incidence of sore throat were significantly higher in the finger group compared to both the control and the sealing group (P<0.001 and P=0.008). The incidence of dysphagia and hoarseness were similar in the three groups. None of the patients in the three groups developed air leak around the endotracheal tube cuff..

CONCLUSIONS

In N(2)O, free anesthesia sealing cuff pressure is an easy, undemanding and safe alternative to the standard technique, regarding effective sealing and low incidence of sore throat.

Epidural analgesia during labor--0.5% lidocaine with fentanyl vs. 0.08% ropivacaine with fentanyl

BACKGROUND

Although lidocaine is a cheap and globally available local anesthetic, yet it is not a popular drug for labor analgesia. This is claimed to its higher intensity of motor block, possibility of transient neurological symptoms (TNS) and its placental transfer with probable drawbacks on fetal well-being. However, these effects could be concentration dependent and, the evidence linking them to lidocaine is still lacking. This study was designed to evaluate the efficacy and safety of 0.5% epidural lidocaine plus fentanyl during labor.

METHODS

One hundred and twenty healthy full term nulliparous women in early labor with a single fetus presented by the vertex were enrolled in this randomized, double-blind clinical trial. Parturient were assigned to receive epidural analgesia either with lidocaine 0.5% plus fentanyl 2 microg(-1 mL) (LF), or ropivacaine 0.08% plus fentanyl 2 microg(-1 ml) (RF) when their cervix was dilated to 4 centimeters. Analgesia was provided with 20 ml bolus of the study solution and maintained at 10 ml(-1) h. Upper level of sensory loss to cold, Visual Analogue Pain Score (VAPS), motor block (modified Bromage score), the duration of the first and second stages of labor, numbers of instrumental vaginal and cesarean deliveries, the neonatal apgar score, patient satisfaction and side effects, were recorded.

RESULTS

There were no significant differences in sensory level, pain scores, duration of the first and second stages of labor, numbers of instrumental and cesarean deliveries, the neonatal apgar scores, patient satisfaction or side effect between groups. Although motor block was significantly high in lidocaine group compared to ropivacaine group (p < 0.05), all parturient were moving satisfactorily in bed.

CONCLUSIONS

Dilute epidural lidocaine (0.5%) with fentanyl effectively and safely initiates epidural analgesia clinically indistinguishable from 0.08% epidural ropivacaine with fentanyl. Although it induces significant motor block compared to ropivacaine, it still preserves maternal ability to move satisfactorily in bed. Whether further reduction in lidocaine concentration could trim down the motor block, remains to be investigated.

Biological and mechanical properties of PMMA-based bioactive bone cements

We reported previously that a bioactive PMMA-based cement was obtained by using a dry method of silanation of apatite-wollastonite glass ceramic (AW-GC) particles, and using high molecular weight PMMA particles. But handling and mechanical properties of the cement were poor (Mousa et al., J Biomed Mater Res 1999;47:336-44). In the present study, we investigated the effect of the characteristics of PMMA powder on the cement. Different cements containing different PMMA powders (CMW1, Surgical Simplex, Palacos-R and other two types of PMMA powders with Mw 270,000 and 1,200,000) and AW-GC filler in 70 wt% ratio except Palacos-R (abbreviated as B-CMW1 and B-Surg Simp, B-Palacos 50 [50 wt% AW-GC filler] and B-Palacos 70 [70 wt% AW-GC filler], B-270 and B-1200) were made. Dough and setting times of B-CMW1, B-Surg Simp B-270 and B-1200 were similar to the commercial CMW1 cement which did not contain bioactive powder (C-CMW1), but B-palacos which contained large PMMA beads with high Mw had delayed setting time. B-270 had the highest bending strength among the tested cements. After 4 and 8 weeks of implantation in the medullary canals of rat tibiae, the bone-cement interface was examined using SEM. The affinity index of B-1200 was significantly higher than the other types of cements. B-270 showed good combination of handling properties, high mechanical properties and showed higher bioactivity with minimal soft tissue interposition between bone and cement compared with commercial PMMA bone cement. This may increase the strength of the bone-cement interface and increase the longevity of cemented arthroplasties.

Bioactive bone cement: effect of surface curing properties on bone-bonding strength

The fact that bisphenol-a-glycidyl methacrylate (bis-GMA)-based cements contain an uncured surface is believed to play an important role when determining the surface curing properties of the cements. Therefore, in the present study, the bone-bonding strength of cement plates having an uncured surface on one side and a cured surface on the other side has been evaluated. These cement plates were composites of a bis-GMA-based resin with either an apatite- and wollastonite-containing glass-ceramic (AW-GC) powder or a hydroxyapatite (HA) powder, respectively designated AWC and HAC. The amount of each of these powders in a composite cement was 70 wt %. We formulate the hypothesis that the uncured surface of a cement plate is bioactive having bone-bonding properties. The goal of the present study was to indicate the bone-bonding strength of the uncured surfaces of AWC and HAC and compare the strength with the respective cured surfaces by a detaching in vivo test, as well as to histologically examine the bone-cement interface. Each plate has been implanted into the tibiae of male Japanese white rabbits, taking care to retain the surface properties, and the so-called "failure load has been measured using a detaching test followed 8 weeks after implantation. The failure load for AWC-plates at the uncured surface (2.05 +/- 1.11 kgf, n = 8) was significantly higher than AWC at its cured surface side (0.28 +/- 0.64 kgf, n = 8). The failure load for HAC-plates at the uncured surfaces (1.40 +/- 0.68 kgf, n = 8) was significantly higher than HAC at its cured surface (0.00 +/- 0.00 kgf, n = 8). Failure loads for AWC at its uncured and cured surfaces were both higher than for HAC, although not significantly. Direct bone formation has been observed histologically for both AWC and HAC on the uncured surfaces, and a Ca-P-rich layer was observed only at the uncured surface of AWC. These findings strongly suggest that uncured surfaces are useful for exposing a bioactive filler on a surface of composites, being very effective in inducing bone bonding.

Bioactive polymethyl methacrylate-based bone cement: comparison of glass beads, apatite- and wollastonite-containing glass-ceramic, and hydroxyapatite fillers on mechanical and biological properties

A new bioactive bone cement (designated GBC) consisting of polymethyl methacrylate (PMMA) as an organic matrix and bioactive glass beads as an inorganic filler has been developed. The bioactive beads, consisting of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) glass, have been newly designed, and a novel PMMA powder was selected. The purpose of the present study was to compare this new bone cement GBC's mechanical properties in vitro and its osteoconductivity in vivo with cements consisting of the same matrix as GBC and either apatite- and wollastonite-containing glass-ceramic (AW-GC) powder (designated AWC) or sintered hydroxyapatite (HA) powder (HAC). Each filler added to the cements amounted to 70 wt %. The bending strength of GBC was significantly higher than that of AWC and HAC (p < 0.0001). Cements were packed into intramedullar canals of rat tibiae in order to evaluate osteoconductivity as determined by an affinity index. Rats were sacrificed at 2, 4, and 8 weeks after operation. An affinity index, which equaled the length of bone in direct contact with the cement expressed as a percentage of the total length of the cement surface, was calculated for each cement. At each time interval studied, GBC showed a significantly higher affinity index than AWC or HAC up to 8 weeks after implantation (p < 0.03). The value for GBC increased significantly with time up to 8 weeks (p < 0.006). The handling property of GBC was comparable with that of PMMA bone cement. Our study revealed that the higher osteoconductivity of GBC was due to the higher bioactivity of the bioactive glass beads at the cement surface and the lower solubility of the new PMMA powder to MMA monomer. In addition, it was found that the smaller spherical shape and glassy phase of the glass beads gave GBC strong enough mechanical properties to be useful under weight-bearing conditions. GBC shows promise as an alternative with improved properties to the conventionally used PMMA bone cement.

Bioactive polymethyl methacrylate-based bone cement: comparison of glass beads, apatite- and wollastonite-containing glass-ceramic, and hydroxyapatite fillers on mechanical and biological properties

A new bioactive bone cement (designated GBC) consisting of polymethyl methacrylate (PMMA) as an organic matrix and bioactive glass beads as an inorganic filler has been developed. The bioactive beads, consisting of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) glass, have been newly designed, and a novel PMMA powder was selected. The purpose of the present study was to compare this new bone cement GBC's mechanical properties in vitro and its osteoconductivity in vivo with cements consisting of the same matrix as GBC and either apatite- and wollastonite-containing glass-ceramic (AW-GC) powder (designated AWC) or sintered hydroxyapatite (HA) powder (HAC). Each filler added to the cements amounted to 70 wt %. The bending strength of GBC was significantly higher than that of AWC and HAC (p < 0.0001). Cements were packed into intramedullar canals of rat tibiae in order to evaluate osteoconductivity as determined by an affinity index. Rats were sacrificed at 2, 4, and 8 weeks after operation. An affinity index, which equaled the length of bone in direct contact with the cement expressed as a percentage of the total length of the cement surface, was calculated for each cement. At each time interval studied, GBC showed a significantly higher affinity index than AWC or HAC up to 8 weeks after implantation (p < 0.03). The value for GBC increased significantly with time up to 8 weeks (p < 0.006). The handling property of GBC was comparable with that of PMMA bone cement. Our study revealed that the higher osteoconductivity of GBC was due to the higher bioactivity of the bioactive glass beads at the cement surface and the lower solubility of the new PMMA powder to MMA monomer. In addition, it was found that the smaller spherical shape and glassy phase of the glass beads gave GBC strong enough mechanical properties to be useful under weight-bearing conditions. GBC shows promise as an alternative with improved properties to the conventionally used PMMA bone cement.

Thiopental induces contraction of rat aortic smooth muscle through Ca(2+) release from the sarcoplasmic reticulum

Little is known about the mechanism of thiopental-induced contraction in vascular smooth muscle. This study aimed to clarify this question by conducting isometric tension experiments and (45)Ca(2+) flux measurements in endothelium-denuded rat aortic rings. Thiopental induced a concentration-dependent contraction under basal tension. This contraction was enhanced when rings were precontracted with phenylephrine in the presence of verapamil. In Ca(2+)-free solution, thiopental-induced contraction was reduced but not abolished with high concentrations. Ca(2+) store depletion with a maximum dose of caffeine in Ca(2+)-free solution further reduced the contraction by subsequent thiopental. Ca(2+) store depletion with thapsigargin completely abolished contraction by thiopental. (45)Ca(2+) influx experiment in the presence of verapamil showed that thiopental could not induce any Ca(2+) influx with or without phenylephrine prestimulation. The (45)Ca(2+) efflux experiment showed more evidence of thiopental-induced Ca(2+) release, which was abolished by thapsigargin. In conclusion, thiopental induces contraction in rat aortic smooth muscle by releasing Ca(2+) from the sarcoplasmic reticulum without Ca(2+) influx.

IMPLICATIONS

This is the first study providing evidence that thiopental-induced vascular contraction is caused by Ca(2+) release from the sarcoplasmic reticulum of the smooth muscle.

Osteoconductivity and bone-bonding strength of high- and low-viscous bioactive bone cements

A study was conducted to evaluate the osteoconductivity and bone-bonding ability of two types of bioactive bone cement, both consisting of apatite and wollastonite containing glass-ceramic powder (AW-P), fused silica glass powder (SG-P), submicron fumed silica as an inorganic filler, and bisphenol-a-glycidyl methacrylate (Bis-GMA) based resin as an organic matrix. The cements had two kinds of formulas: one (dough-type cement; designated DTC) composed of 85% (w/w) filler and 15% resin, which was developed for fixation of the acetabular component in total hip arthroplasty and could be handled manually; and one (injection-type cement; designated ITC) composed of 79% (w/w) filler and 21% resin. ITC was developed for fixation of the femoral component and, because it had a lower viscosity than DTC, could be injected. The DTC and ITC both contained 73% AW-P, 25% SG-P, and 2% fumed silica in the weight ratio of the filler component. Two other types of cement, both of which consisted of 83.3% AW-P or SG-P, 1.7% fumed silica, and 15% resin, were used as reference material (designated AWC or SGC) for a detaching test. Following the packing of bone defects in the rat tibiae with either DTC or ITC, histological examination revealed that the DTC and ITC had both directly contacted the bone and were almost completely surrounded by bone by 16 weeks after the surgery and that no marked biodegradation had occurred at 52 weeks postimplantation. Rectangular plates (2 x 10 x 15 mm) of AWC, DTC, ITC, and SGC were implanted into the metaphysis of the tibia of male rabbits and the failure load was measured by a detaching test at 10 and 25 weeks after implantation. The failure loads of AWC, DTC, ITC, and SGC were 3.65, 2.21, 2.44, and 0.04 kgf at 10 weeks and 4.87, 2. 81, 2.82, and 0.13 kgf at 25 weeks, respectively. Observation of the bone-implant interface by scanning electron microscopy and energy dispersive X-ray microanalysis revealed that all the samples except SGC formed direct contact with the bone and that only AWC-implanted tibiae had a layer of a low calcium and phosphorus level at the bone-implant interface. Results showed that DTC and ITC have excellent osteoconductivity and bone-bonding ability under non-weight-bearing conditions.

Effect of silane treatment and different resin compositions on biological properties of bioactive bone cement containing apatite-wollastonite glass ceramic powder

In methylmethacrylate (MMA)-based cements containing bioactive particles, polymethylmetacrylate (PMMA) is known to suppress the bioactivity of Bioglass(R) and apatite-wollastonite glass ceramic (AW-GC). Little is known about the effect of different silane treatment methods on the bioactivity of AW-GC. MMA-based cement plates containing dry silanated AW-GC particles and PMMA particles of different molecular weights (12,000-900,000) were immersed in simulated body fluid (SBF). Cements containing PMMA particles of high molecular weight formed an apatite layer on the surface after 24 h. Using PMMA particles with a molecular weight of 60,000 and AW-GC particles silanated with different methods (dry method vs. slurry method), cement plates were made and immersed in SBF. Only cement plates containing dry silanated AW-GC particles showed apatite formation in SBF after 3 days. In vivo implantation in rat tibias of MMA-based cement containing dry silanated AW-GC particles and PMMA particles (molecular weight 900,000) demonstrated an affinity index of 32.1 +/- 15.8% after 8 weeks of implantation compared to 89.4 +/- 10.7% achieved by bisphenol-A-glycidyl methacrylate based cement containing the same bioactive powder. By using a dry method of silane treatment and high molecular weight PMMA particles, the bioactivity of cement based on MMA monomer was achieved; but further effort is needed to improve the mechanical properties of the composite.

Bone-bonding ability of bioactive bone cement under mechanical stress

Bioactive bone cement (BABC) is able to bond to bone through a Ca-P rich layer. It was evaluated so far in a rat tibial model, where no mechanical stresses are supposed to take place. The objective is to investigate the behavior of BABC in the environment of posterolateral spinal fixation model, in which the bone cement interface is exposed to continuous mechanical stress. Japanese white rabbits were used. Fixation of L5-L6 segment was done by wiring the spinous and transverse processes of L5 and L6 vertebrae. Then BABC was applied over the transverse processes and the intertransverse process membrane on both sides. Polymethylmethacrylate (PMMA) bone cement was used similarly in the control group. Animals were sacrificed after 1 day, 4, 8, and 16 weeks postoperatively. Bone cement interface was examined using Giemsa surface staining and SEM, and affinity index was measured. Biomechanical testing was done nondestructively in right and left torsion. BABC bonded to bone directly with no intervening soft tissue at 4, 8, and 16 weeks, while soft tissue was consistently seen between PMMA bone cement and bone. BABC-spine constructs were stiffer than PMMA-spine constructs at all time intervals. BABC bonded directly to bone under mechanical stress and afforded stiffer fixation than PMMA bone cement.

Effect of bioactive filler content on mechanical properties and osteoconductivity of bioactive bone cement

We took three types of bioactive bone cement (designated AWC, HAC, and TCPC), each with a different bioactive filler, and evaluated the influence of each filler on the mechanical properties and osteoconductivity of the cement. The cements consisted of bisphenol-a-glycidyl methacrylate-based (Bis-GMA based) monomers as an organic matrix, with a bioactive filler of apatite/wollastonite containing glass-ceramic (AW-GC) or sintered hydroxyapatite (HA) or beta-tricalcium phosphate (beta-TCP) powder. Each filler was mixed with the monomers in proportions of 50, 70, and 80% (w/w), giving a total of nine cement subgroups. The nine subgroups were designated AWC50, AWC70, AWC80, HAC50, HAC70, HAC80, TCPC50, TCPC70, and TCPC80. The compressive and bending strengths of AWC were found to be higher than those of HAC and TCPC for all bioactive filler contents. We also evaluated the cements in vivo by packing them into the intramedullary canals of rat tibiae. To compare the osteoconductivity of the cements, an affinity index was calculated for each cement; it equaled the length of bone in direct apposition to the cement, expressed as a percentage of the total length of the cement surface. Microradiographic examination up to 26 weeks after implantation revealed that AWC showed a higher affinity index than HAC and TCPC for each filler content although the affinity indices of all nine subgroups (especially the AWC and HAC subgroups) increased with time. New bone had formed along the AWC surface within 4 weeks, even in the cement containing AW-GC filler at only 50% (w/w); observation of the cement-bone interfaces using a scanning electron microscope showed that all the cements had directly contacted the bone. At 4 weeks the AWC had bonded to the bone via a 10 micron-thick reactive layer; the width of the layer, in which partly degraded AW-GC particles were seen, became slightly thicker with time. On the other hand, in the HAC- and TCPC-implanted tibiae, some particles on the cement surface were surrounded by new bone and partly absorbed or degraded. The results suggest that the stronger bonding between the inorganic filler and the organic matrix in the AWC cements gave them better mechanical properties. The results also indicate that the higher osteoconductivity of AWC was caused by the higher reactivity of the AW-GC powder on the cement surface.