Efficacy and Safety of Antibiotic Impregnated Microporous Nanohydroxyapatite Beads for Chronic Osteomyelitis Treatment: A Multicenter, Open-Label, Prospective Cohort Study.

Chronic osteomyelitis is still a serious health problem that causes disabling conditions and has an impact on the quality of life. The objective of this study was to determine the clinical efficacy and safety of localized antibiotics delivery via impregnated microporous nanohydroxyapatite (nHA-ATB) beads for chronic osteomyelitis treatment. A total of 62 patients were enrolled in this study. After radical surgical debridement, the bone defect was filled with three types of antibiotics (vancomycin or gentamicin or fosfomycin) impregnated HA beads. The follow-up period was 48 weeks. It was found that the success rate was approximately 98% with a re-infection in only one patient. Quality of life of all patients after treatment improved significantly over time. Systemic exposure to vancomycin and gentamicin after beads implantation was limited and high local antibiotics concentrations were found in wound drainage fluid at 24, 48 and 72 h. Blood biochemistry measurements did not show any nephrotoxic or hepatotoxic effects. 20 adverse events were reported, but 90% of the events were resolved without having to remove the beads and the patients recovered. Satisfactory outcomes were observed in terms of success rate, quality of life and adverse effect. nHA-ATB beads impregnated by vancomycin or gentamicin or fosfomycin could potentially be employed as an alternative product of choice for localized antibiotics delivery in chronic osteomyelitis treatment.

Polycaprolactone versus collagen membrane and 1-year clinical outcomes: A randomized controlled trial.

BACKGROUND: Polycaprolactone (PCL) is a synthetic aliphatic polyester widely used in biomedical applications with biodegradability in the body and promotes cell proliferation and differentiation. A newly developed bilayered PCL membrane was developed for possibly being used as a membrane in guided bone regeneration (GBR). PURPOSE: To compare the clinical efficacy between a newly developed bilayered PCL membrane with a Cytoplast™ RTM collagen membrane for GBR with simultaneous implant placement. MATERIALS AND METHODS: Twenty-four patients were randomized to PCL or RTM group, and a total of 24 dental implants were placed. Primary outcomes were patient mean buccal bone thickness (BBT) immediately postimplantation and at 6 months using cone-beam CT and soft tissue surface dimensional changes (STC) at crown insertion, 6 months, and 1 year after loading using intraoral scanner. Secondary outcomes included success rate, clinical parameters, healing index, implant stability, pink esthetic score, and marginal bone levels. RESULTS: The percentage of reduced BBT at 6 months was 32.38%, 25.94%, and 23.96% in the test group and 34.42%, 14.75%, and 6.34% in the control group at the corresponding levels. The mean difference of changed BBT associated with PCL membrane, when compared to collagen membrane, at 6 months was -0.02 ± 0.18 mm (95% confidence interval [CI]: -0.40 to 0.35), 0.29 ± 0.28 mm (95% CI: -0.29 to 0.87), and 0.62 ± 0.38 mm (95% CI: -0.17 to 1.42) at 0, 2, and 4 mm from implant shoulder. Minimal loss of STC was observed in both groups up to 1 year of loading. The mean difference loss of surface dimensional change associated with PCL membrane, when compared to collagen membrane, at 1 year of loading was 0.31 ± 0.19 mm (95% CI: -0.07 to 0.70), 0.22 ± 0.26 mm (95% CI: -0.33 to 0.76), and 0.17 ± 0.30 mm (95% CI: -0.45 to 0.78) at 0, 2, and 4 mm from implant shoulder. None of these differences were statistically significant (unpaired t-test, degrees of freedom [df] = 22; p > 0.05). CONCLUSION: Within the limits of this trial, both barrier membranes resulted in comparable outcomes for GBR with implant placement after 1 year in function. Further research is necessary with a larger sample size.

Customized 3D printed nanohydroxyapatite bone block grafts for implant sites: A case series.

PATIENTS: A case series of 12 patients (mean age, 53.5 years) with horizontal ridge deficiencies had augmentations with customized 3D printed nanohydroxyapatite (3DHA) block grafts prior to implant placement. 3DHA graft materials were fabricated to fit the individual patient defects using DICOMs from CBCT images obtained from each patient. The CBCT images were then converted into the STL file format and 3DHA was reconstructed by 3D printing. Surgical bone augmentation consisted of 3DHA incorporating concentrated growth factors (CGFs) and platelet-rich fibrin (PRF) membrane. At 6 months, a bone biopsy and implantation were performed. The primary outcome was horizontal bone gain after 6 months. The secondary outcomes included information on the clinical outcomes, dimensions, and histomorphometric results. DISCUSSION: The 3DHA block graft was successful in 10 of 12 patients. Graft adjustment was not required. All 3DHA adapted and fit well at all defect sites. Maximum mean horizontal bone gains were 3.06 ± 1.02 and 3.56 ± 0.23 mm from the DICOMs and STL data sets, respectively. The volume gain was 229.8 ± 82.96 mm3. A low pain score after surgery was reported of 1.41 ± 0.51, while the healing index score increased with a maximum mean of 4.7 ± 0.67. Thirteen implants were placed with good primary stability (ISQ = 65 ± 4.08), without additional guided bone regeneration. Histomorphometric analysis revealed that new bone formation, bone tissue, residual grafts, and connective tissue were 28.6 ± 1.88, 30.48 ± 4.81, 19.82 ± 4.07, and 20.81 ± 4.41%, respectively. CONCLUSIONS: A customized 3DHA block graft is a viable treatment option for primary implant-site augmentation.

Osteogenic differentiation and proliferation potentials of human bone marrow and umbilical cord-derived mesenchymal stem cells on the 3D-printed hydroxyapatite scaffolds.

Mesenchymal stem cells (MSCs) are a promising candidate for bone repair. However, the maintenance of MSCs injected into the bone injury site remains inefficient. A potential approach is to develop a bone-liked platform that incorporates MSCs into a biocompatible 3D scaffold to facilitate bone grafting into the desired location. Bone tissue engineering is a multistep process that requires optimizing several variables, including the source of cells, osteogenic stimulation factors, and scaffold properties. This study aims to evaluate the proliferation and osteogenic differentiation potentials of MSCs cultured on 2 types of 3D-printed hydroxyapatite, including a 3D-printed HA and biomimetic calcium phosphate-coated 3D-printed HA. MSCs from bone marrow (BM-MSCs) and umbilical cord (UC-MSCs) were cultured on the 3D-printed HA and coated 3D-printed HA. Scanning electron microscopy and immunofluorescence staining were used to examine the characteristics and the attachment of MSCs to the scaffolds. Additionally, the cell proliferation was monitored, and the ability of cells to differentiate into osteoblast was assessed using alkaline phosphatase (ALP) activity and osteogenic gene expression. The BM-MSCs and UC-MSCs attached to a plastic culture plate with a spindle-shaped morphology exhibited an immunophenotype consistent with the characteristics of MSCs. Both MSC types could attach and survive on the 3D-printed HA and coated 3D-printed HA scaffolds. The MSCs cultured on these scaffolds displayed sufficient osteoblastic differentiation capacity, as evidenced by increased ALP activity and the expression of osteogenic genes and proteins compared to the control. Interestingly, MSCs grown on coated 3D-printed HA exhibited a higher ALP activity and osteogenic gene expression than those cultured on the 3D-printed HA. The finding indicated that BM-MSCs and UC-MSCs cultured on the 3D-printed HA and coated 3D-printed HA scaffolds could proliferate and differentiate into osteoblasts. Thus, the HA scaffolds could provide a suitable and favorable environment for the 3D culture of MSCs in bone tissue engineering. Additionally, biomimetic coating with octacalcium phosphate may improve the biocompatibility of the bone regeneration scaffold.

Cefazolin Loaded Oxidized Regenerated Cellulose/Polycaprolactone Bilayered Composite for Use as Potential Antibacterial Dural Substitute.

Oxidized regenerated cellulose/polycaprolactone bilayered composite (ORC/PCL bilayered composite) was investigated for use as an antibacterial dural substitute. Cefazolin at the concentrations of 25, 50, 75 and 100 mg/mL was loaded in the ORC/PCL bilayered composite. Microstructure, density, thickness, tensile properties, cefazolin loading content, cefazolin releasing profile and antibacterial activity against S. aureus were measured. It was seen that the change in concentration of cefazolin loading affected the microstructure of the composite on the rough side, but not on the dense or smooth side. Cefazolin loaded ORC/PCL bilayered composite showed greater densities, but lower thickness, compared to those of drug unloaded composite. Tensile modulus was found to be greater and increased with increasing cefazolin loading, but tensile strength and strain at break were lower compared to the drug unloaded composite. In vitro cefazolin release in artificial cerebrospinal fluid (aCSF) consisted of initial burst release on day 1, followed by a constant small release of cefazolin. The antibacterial activity was observed to last for up to 4 days depending on the cefazolin loading. All these results suggested that ORC/PCL bilayered composite could be modified to serve as an antibiotic carrier for potential use as an antibacterial synthetic dura mater.

Clinical evaluation of 3D printed nano-porous hydroxyapatite bone graft for alveolar ridge preservation: A randomized controlled trial.

BACKGROUND/PURPOSE: Ridge resorption after tooth extraction may result in inadequate bone volume and unfavorable ridge architecture for ideal implant placement. The use of bone substitutes has been advocated to fill extraction sites and to enhance primary implant stability. This study was made to evaluate the clinical efficacy of novel 3D printed nano-porous hydroxyapatite (3DP HA, test group) in comparison to nano-crystalline bone graft (NanoBone®, control group) in alveolar ridge preservation prior to implant placement. MATERIALS AND METHODS: Thirty patients were randomized into two groups following tooth extraction. All extracted sockets were filled with 3DP HA or NanoBone® and covered with a non-resorbable membrane. After four months, cone-beam computed tomography (CBCT) and intraoral scanner were used to measure dimensional changes of bone and soft tissue surface. Bone core specimens were harvested for histological analysis during implant osteotomy. Implant stability was assessed using a modified damping capacity analysis. RESULTS: At four months postoperatively, dimensional changes in soft tissue surface resorption were less in the test group than in the control group; however, alveolar bone resorption was the same in both groups. Histological analysis revealed new bone formation, residual graft and fibrous connective tissue in both groups. The average primary implant stability (IST) value for both groups was approximately 70. There was no statistically significant difference in all parameters between two groups (p > 0.05). CONCLUSION: 3DP HA could potentially be used as an alternative bone graft material for alveolar ridge preservation.

In vitro resorbability and granular characteristics of 3D-printed hydroxyapatite granules versus allograft, xenograft, and alloplast for alveolar cleft surgery applications.

Three-dimensionally printed hydroxyapatite (3DP HA) was investigated in regards to its functional properties supporting bone regeneration and tooth movement in alveolar cleft applications. Commercially available bovine xenograft (BXG), biphasic calcium phosphate alloplast (BCP), and two types of freeze-dried bone allograft granules (FDBA and FDBA-CMC) were employed as control samples. Degradability was studied by submerging the samples in pH 7.4 buffered solution at 37°C for 28 days and determining subsequent weight loss percentage. The wicking property and granular agglomeration were evaluated by putting the granules in contact with deionized water, blood, and phosphate-buffered saline (PBS). Both of FDBA and FDBA-CMC showed the greatest weight loss at 28 days followed by 3DP HA. In contrast, 3DP HA showed significantly greater wicking ability than other samples for all liquid types. FDBA-CMC exhibited the greatest granular agglomeration for all liquid types followed by 3DP HA. 3DP HA was found to be a favorable candidate for bone grafting in alveolar cleft treatment.

Effectiveness of bilayer porous polyethylene membrane for alveolar ridge preservation: A randomized controlled trial.

BACKGROUND: Porous polyethylene has been successfully used in several medical applications with good outcomes. Based on this, a new bilayer porous polyethylene membrane (B-PPM) was developed for possibly being used as a membrane in alveolar ridge preservation. PURPOSE: To evaluate the clinical efficacy of a new B-PPM in comparison to high-density polytetrafluoroethylene membrane (d-PTFE) in alveolar ridge preservation. MATERIALS AND METHODS: Thirty patients were randomized into two groups according to the membranes used to cover the socket (B-PPM or d-PTFE). Wound healing was monitored at day 1, 3, 7, 14, 28, and 4 months postoperatively. Dimensional changes of alveolar ridge were measured immediately after tooth extraction and at 4 months later using intraoral scanner and cone beam computed tomography. Bone cores were harvested before implant placement. Implant stability at insertion and prior to prosthesis delivery were also measured. RESULTS: No significant difference in socket wound closure between groups was observed excepting at day 14 that B-PPM showed a faster wound closure than d-PTFE (P = .03). Greater bone resorptions were seen on buccal than lingual side and on coronal than apical part of the alveolar ridge. No significant difference in dimensional changes of alveolar ridge, new bone formation, connective tissue content, residual bone grafts, and implant stability between two groups. CONCLUSION: B-PPPM was safe and effective for alveolar ridge preservation.

In vivo evaluation of bilayer ORC/PCL composites in a rabbit model for using as a dural substitute.

OBJECTIVE: After a neurosurgical procedure, dural closure is commonly needed to prevent cerebrospinal fluids (CSF) leakage and to reduce the risk of complications, including infections and chronic inflammatory reactions. Although several dural substitutes have been developed, their manufacturing processes are complicated and costly and that many of them have been implicated in causing postoperative complications. This study aimed to assess the effectiveness and safety of new bilayer ORC/PCL composites in a rabbit model. METHODS: Two formulations of bilayer oxidized regenerated cellulose (ORC)/poly ε-caprolactone (PCL) knitted fabric-reinforced composites and an autologous graft (pericranium) were employed for dural closure in forty-five male rabbits. Systemic reaction and the local reaction of the samples were assessed and compared at one-, three- and six-months post-implantation by blood chemistry and gross, and microscopic assessment using hematoxylin-eosin and Masson's trichrome stains. RESULTS: No signs of CSF leakage or systemic infection were seen for all samples. All samples demonstrated minimal adhesion to adjacent tissues. The degree of host fibrous connective tissue ingrowth into both composites was comparable to that of the autologous group, but bone formation and osteoclast activities were significantly greater. Both composites progressively degraded over times and the residual thickness of the nonporous layer was 50% of the initial thickness at six months post-implantation. DISCUSSION: Bilayer ORC/PCL composites were successfully employed for dural closure in the rabbit model. They were biocompatible and could support dural regeneration comparable to that of the autologous group, but induced greater osteogenesis.

Clinical and histological evaluations of alveolar ridge augmentation using a novel bi-layered porous polyethylene barrier membrane.

Guided bone regeneration (GBR) is an effective alveolar ridge reconstruction technique used before or at implant placement. The combination of various barrier membranes and bone substitutes has been employed. This study aimed to perform a preliminarily evaluation of the safety and performance of a new nonabsorbable bi-layered porous polyethylene (PPE) membrane, in combination with a freeze-dried cortical bone allograft in posterior mandibular ridge augmentation. Fifteen adults who had combined posterior mandibular defects were included for ridge augmentation via GBR using PPE membrane and allograft before implant placement. The keratinized mucosa width (KW), ridge width (RW), ridge height (RH), distance from measurement matrix to bone (DMB), and horizontal alveolar width at 14.0 mm apical to the occlusal plane (HAW) were clinically measured at 15 intended implant sites before and after the augmentation. Fifteen biopsy specimens were harvested at the implant sites for histological analysis. All the subjects completed the whole study. The KW and RH showed minor gains by 0.2 ± 1.4 mm and 0.9 ± 2.3 mm respectively; however, no statistically significant differences were found between, before, and after the augmentation (P > 0.05). In contrast, the RW and HAW significantly increased by 4.8 ± 1.6 mm and 2.3 ± 1.7 mm, respectively, (P ≤ 0.001), while DMB significantly decreased by 1.0 ± 0.8 mm after treatment (P < 0.001). Histological analysis revealed that allograft underwent active bone remodeling. The PPE membrane was adequately safe and efficient to use with allograft in GBR for the reconstruction of combined ridge defects. Although some complications were observed, these were manageable and subsequently lead to successful implant placement for all the subjects. However, further randomized controlled trials are still needed to confirm these findings.

Performance evaluation of bilayer oxidized regenerated cellulose/poly ε-caprolactone knitted fabric-reinforced composites for dural substitution.

Ideally, alloplastic dural substitute should have functional properties resembling human dura mater and retain a watertight closure to prevent cerebrospinal leakage. Therefore, functional properties for successful dural closure application of newly developed bilayer oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composites were studied and compared with human cadaveric dura mater and three commercial dural substitutes including two collagen matrices and one synthetic poly-L-lactide patch. It was found that oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composites uniquely contained a bilayer structure consisting of micropores distributed within the relatively dense microstructure. Density, tensile properties and stitch tear strength of oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composites were found to be closed to human cadaveric dura mater than those of dense-type and porous-type dural substitutes. Water tightness performance in both sutured and non-sutured forms of oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composites was slightly inferior to human cadaveric dura mater, but still better than those of commercial dural substitutes. This study revealed that oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composite showed better functional properties than typical dural substitutes and was found to be a good candidate for being employed as a dural substitute. The role and relationship of both microstructure and the type of materials on the functional properties and water tightness of the dural substitutes were also elucidated.

Evaluation of tissue ingrowth and reaction of a porous polyethylene block as an onlay bone graft in rabbit posterior mandible.

PURPOSE: A new form of porous polyethylene, characterized by higher porosity and pore interconnectivity, was developed for use as a tissue-integrated implant. This study evaluated the effectiveness of porous polyethylene blocks used as an onlay bone graft in rabbit mandible in terms of tissue reaction, bone ingrowth, fibrovascularization, and graft-bone interfacial integrity. METHODS: Twelve New Zealand white rabbits were randomized into 3 treatment groups according to the study period (4, 12, or 24 weeks). Cylindrical specimens measuring 5 mm in diameter and 4.5 mm in thickness were placed directly on the body of the mandible without bone bed decortication, fixed in place with a titanium screw, and covered with a collagen membrane. Histologic and histomorphometric analyses were done using hematoxylin and eosin-stained bone slices. Interfacial shear strength was tested to quantify graft-bone interfacial integrity. RESULTS: The porous polyethylene graft was observed to integrate with the mandibular bone and exhibited tissue-bridge connections. At all postoperative time points, it was noted that the host tissues had grown deep into the pores of the porous polyethylene in the direction from the interface to the center of the graft. Both fibrovascular tissue and bone were found within the pores, but most bone ingrowth was observed at the graft-mandibular bone interface. Bone ingrowth depth and interfacial shear strength were in the range of 2.76-3.89 mm and 1.11-1.43 MPa, respectively. No significant differences among post-implantation time points were found for tissue ingrowth percentage and interfacial shear strength (P>0.05). CONCLUSIONS: Within the limits of the study, the present study revealed that the new porous polyethylene did not provoke any adverse systemic reactions. The material promoted fibrovascularization and displayed osteoconductive and osteogenic properties within and outside the contact interface. Stable interfacial integration between the graft and bone also took place.

Enhancement of mechanical properties of 3D printed hydroxyapatite by combined low and high molecular weight polycaprolactone sequential infiltration.

A new infiltration technique using a combination of low and high molecular weight polycaprolactone (PCL) in sequence was developed as a mean to improve the mechanical properties of three dimensional printed hydroxyapatite (HA). It was observed that using either high (M n~80,000) or low (M n~10,000) molecular weight infiltration could only increase the flexural modulus compared to non-infiltrated HA, but did not affect strength, strain at break and energy at break. In contrast, a combination of low and high molecular infiltration in sequence increased the flexural modulus, strength and energy at break compared to those of non-infiltrated HA or infiltrated by high or low molecular weight PCL alone. This overall enhancement was found to be attributed to the densification of low molecular weight PCL and the reinforcement of high molecular PCL concurrently. The combined low and high molecular weight infiltration in sequence also maintained high osteoblast proliferation and differentiation of the composites at the similar level of the HA. Densification was a dominant mechanism for the change in modulus with porosity and density of the infiltrated HA/PCL composites. However, both densification and the reinforcing performance of the infiltration phase were crucial for strength and toughening enhancement of the composites possibly by the defect healing and stress shielding mechanisms. The sequence of using low molecular weight infiltration and followed by high molecular infiltration was seen to provide the greatest flexural properties and highest cells proliferation and differentiation capabilities.

Bilayer oxidized regenerated cellulose/poly ε-caprolactone knitted fabric-reinforced composite for use as an artificial dural substitute.

A novel bilayer knitted fabric-reinforced composite for potentially being used as a dural substitute was developed by solution infiltration of oxidized regenerated cellulose knitted fabric (ORC) with poly ε-caprolactone (PCL) solution at various concentrations ranging 10-40 g/100 mL. It was found that the density of all formulations did not differ significantly and was lower than that of the human dura. Microstructure of the samples typically comprised a bilayer structure having a nonporous PCL layer on one side and the ORC/PCL composite layer on another side. Tensile modulus and strength of the samples initially decreased with increasing PCL solution concentration for up to 20 g/100 mL and re-increased again with further increasing PCL solution concentration. Strain at break of all formulations were not significantly different. Watertight test revealed that all composites could prevent leakage at the pressure within the normal range of intracranial pressure. In vitro degradation study revealed that the weight loss percentage and change in tensile properties of all samples displayed biphasic profile comprising an initially rapid decrease and followed by a gradual decrease with incubation times afterward. Micro and macro porous channels were observed to be in situ generated in the composite layer by ORC dissolution and PCL resorption during degradation while nonporous layer remained relatively unchanged. The degradation rate was found to decrease with increasing PCL solution concentration. In vitro biocompatibility using alamar blue assay on selected samples showed that fibroblasts could attach and proliferate well at all incubation periods.

Influence of process parameters on the content of biomimetic calcium phosphate coating on titanium: a Taguchi analysis.

In this study, a statistical design of experimental methodology based on Taguchi orthogonal design has been used to study the effect of various processing parameters on the amount of calcium phosphate coating produced by such technique. Seven control factors with three levels each including sodium hydroxide concentration, pretreatment temperature, pretreatment time, cleaning method, coating time, coating temperature and surface area to solution volume ratio were studied. X-ray diffraction revealed that all the coatings consisted of the mixture of octacalcium phosphate (OCP) and hydroxyapatite (HA) and the presence of each phase depended on the process conditions used. Various content and size (-1-100 µm) of isolated spheroid particles with nanosized plate-like morphology deposited on the titanium surface or a continuous layer of plate-like nanocrystals having the plate thickness in the range of -100-300 nm and the plate width in the range of 3-8 µm were formed depending on the process conditions employed. The optimum condition of using sodium hydroxide concentration of 1 M, pretreatment temperature of 70 degrees C, pretreatment time of 24 h, cleaning by ultrasonic, coating time of 6 h, coating temperature of 50 degrees C and surface area to solution volume ratio of 32.74 for producing the greatest amount of the coating formed on the titanium surface was predicted and validated. In addition, coating temperature was found to be the dominant factor with the greatest contribution to the coating formation while coating time and cleaning method were significant factors. Other factors had negligible effects on the coating performance.

Preparation and characterization of nanosized silver phosphate loaded hydroxyapatite by single step co-conversion process.

The preparation and characterization of silver phosphate nanoparticles loaded hydroxyapatite aiming to enhance the bactericidal performance by a single step co-conversion technique using low temperature phosphorization in the presence of various silver nitrate concentration (AgNO3, ranging 0.001-0.1M) was performed. Characterization by using X-ray diffraction, infrared spectroscopy and transmission electron microscopy showed that hydroxyapatite and silver phosphate were the main phases in all converted samples and the microstructure comprised the distribution of spherical-shaped silver phosphate nanoparticles within the cluster of hydroxyapatite nanocrystals. Total silver content (ranging 0.09-5.6%) in the converted samples was found to increase with increasing silver nitrate content. Flexural modulus and strength of converted samples remained unchanged for samples using silver nitrate between 0.001 and 0.01M, but decreased at greater silver nitrate concentration. Antibacterial activity of two selected samples (0.001 and 0.005M AgNO3) against two bacterial strains (Pseudomonas aeruginosa and Staphylococcus aureus) was observed since 100% reduction of viable cells after 24h contact was detected. Cytotoxic potential by MTT assay of sample using 0.001M AgNO3 was only observed at 24h extraction, but was seen at all extraction periods (24-72h) for sample using 0.005M AgNO3.

Fit-and-fill analysis of trochanteric gamma nail for the Thai proximal femur: a virtual simulation study.

The present study present a three-dimensional virtual simulation method to evaluate the fit-and-fill effect of the insertion of a trochanteric gamma nail (TGN) in 98 Thai dadaveric proximal femora. The circular best fit of the 2-dimensional cross-section of the femoral canal and the nail at 4 levels [d100, d120, d140 and d160] which were located at 100, 120, 140 and 160 mm distal to the tip of the greater trochanter were calculated. The evaluation of each level included, 1) the diameters of the medullary canal, 2) the percentage of area filled by the nail in the unreamed medullary canal, 3) the minimal reamer diameter that required enlargement of the canal to accommodate TGN insertion, 4) the minimal inner cortical reaming thickness that needed to be removed, 5) the percentage of cortical bone area that needed to be removed prior to nail insertion and 6) the deviation of the nail center from the center of the medullary canal. The results showed that at 4 studied locations the diameter of unreamed medullary canal averaged 10.3 to 11.8 mm. The nail cross-section that could fill the medullary canal averaged 86.9-95.1%. The minimal reaming diameter for the medullary canal to accommodate the TGN insertion averaged 11.3 to 12.3 mm. The inner cortical thickness that should be removed averaged 0.6 to 0.8 mm. The cortical bone that needed to be removed averaged 13.6 to 19.3% of the total cortical area. The deviation of the nail center from the canal center averaged 0.3 to 0.8 mm. The present study showed some mismatching of the TGN to that of the Thai proximal femur. Appropriate reaming to prepare the medullary canal should be considered prior to TGN insertion to prevent technical problem. Future re-design of the implant may be considered for Thai patients.