Bone Hole Research Articles

Numerical evaluation of sequential bone drilling strategies based on thermal damage

Sequentially drilling multiple holes in bone is used clinically for surface preparation to aid in fusion of a joint, typically under non-irrigated conditions. Drilling induces a significant amount of heat and accumulates after multiple passes, which can result in thermal osteonecrosis and various complications. To understand the heat propagation over time, a 3D finite element model was developed to simulate sequential bone drilling. By incorporating proper material properties and a modified bone necrosis criteria, this model can visualize the propagation of damaged areas. For this study, comparisons between a 2.0 mm Kirschner wire and 2.0 mm twist drill were conducted with their heat sources determined using an inverse method and experimentally measured bone temperatures. Three clinically viable solutions to reduce thermally-induced bone damage were evaluated using finite element analysis, including tool selection, time interval between passes, and different drilling sequences. Results show that the ideal solution would be using twist drills rather than Kirschner wires if the situation allows. A shorter time interval between passes was also found to be beneficial as it reduces the total heat exposure time. Lastly, optimizing the drilling sequence reduced the thermal damage of bone, but the effect may be limited. This study demonstrates the feasibility of using the proposed model to study clinical issues and find potential solutions prior to clinical trials.

In vivo administration of dental epithelial stem cells at the apical end of the mouse incisor.

Cell-based tissue regeneration is an attractive approach that complements traditional surgical techniques for replacement of injured and lost tissues. The continuously growing rodent incisor provides an excellent model system for investigating cellular and molecular mechanisms that underlie tooth renewal and regeneration. An active population of dental epithelial progenitor/stem cells located at the posterior part of the incisor, commonly called cervical loop area, ensures the continuous supply of cells that are responsible for the secretion of enamel matrix. To explore the potential of these epithelial cells in therapeutic approaches dealing with enamel defects, we have developed a new method for their in vivo administration in the posterior part of the incisor. Here, we provide the step-by-step protocol for the isolation of dental epithelial stem cells and their delivery at targeted areas of the jaw. This simple and yet powerful protocol, consisting in drilling a hole in the mandibular bone, in close proximity to the cervical loop area of the incisor, followed up by injection of stem cells, is feasible, reliable, and effective. This in vivo approach opens new horizons and possibilities for cellular therapies involving pathological and injured dental tissues.

Three-Dimensional Porous Gelapin-Simvastatin Scaffolds Promoted Bone Defect Healing in Rabbits.

Treatment of large bone defects (LBDs) is technically demanding. Tissue engineering is an option. A bioactive graft may be produced by combining tissue scaffolds and healing promotive factors in order to accelerate bone repair. We investigated the role of Simvastatin (Sim)-embedded porous Gelapin (Gel) scaffold on experimental bone healing. At first, the effectiveness of different concentrations of Gel and Sim powders was investigated in an experimentally induced femoral hole model in rabbits (n = 6) for 30 days. Then bone bioactive grafts were produced by combination of the effective concentrations of Gel, Sim, and Genipin. The bioimplants were subcutaneously tested in a rabbit model (n = 9) to determine their biocompatibility and biodegradability for 10-30 days. Finally, a large radial bone defect model was produced in rabbits (n = 20), and the bioimplants were inserted in the defects. The untreated and autograft-treated bone defects were served as controls. The animals were euthanized after 30 and 60 days of bone injury. The bone samples were evaluated by radiography, three-dimensional CT scan, bone densitometry, histopathology, and nano-indentation. At a concentration of 5 mg/hole, Sim closed the femoral bone holes after 30 days, while in the defect, autograft, and Gel groups, the holes were open. Both the Gel and Gel-Sim scaffolds were biocompatible and biodegradable. Subcutaneously, the Gel-Sim scaffold was replaced with the newly regenerated ectopic bone after 30 days. After implantation of the Gel-Sim scaffold in the radial bone defects, the scaffold was completely replaced with new woven bone after 30 days which was then matured and remodeled into a cortical bone after 60 days. Sixty days after bone injury, the Gel-Sim-treated defects had significantly higher bone volume, matrix mineralization, elastic modulus, and contact hardness when compared to the controls. The Gel-Sim scaffold may be a suitable option in managing LBDs.

The Effect of Novel Flax Oil-Based Implant Coating on Bone Healing Process (In Vivo Animal Study)

Objective This pilot study was designed to investigate the effect of new implant coating material on ‎postoperative bone healing process.‎ Study Design experimental formula of flax oil-based implant coating was prepared.Twelve (12) white New Zealand male rabbits were randomly distributed into four groups (n=3). ‎Surgery was performed to prepare 2mm hole in the zygomatic bone. The right side was ‎filled ‎with the test material (test group). whereas the hole in the left side of the same animal was left ‎material free. Bone healing process was investigated after 3,7,14, and 21 days. ‎ Results New growth of normal bone explained by active bone apposition was observed ‎in the ‎test operation area in the marrow space‎ after three days, less postoperative ‎inflammation was observed explained by less inflammatory cells in the operation area.‎ Conclusions The new formula could represent a promising implant coating material for better bone healing process and hence faster osseointegration. Keywords Flax seed, coating, implant, Bone, Rabbit

Postoperative evaluation of drill holes for arthroscopic Bankart repair with suture anchors by the use of computed tomography.

Here we investigated the angle and placement of bone holes for suture anchors using postoperative computed-tomography scapula scans. The study group comprised 20 shoulders from 20 consecutive patients (13 males and seven females; mean age 23.4 years) who underwent arthroscopic Bankart repair. All anchors were inserted through the anterior portal after establishing a bone hole at the edge of the glenoid articular surface using a drill. Computed tomography images of the scapula were taken 1 month postoperatively and used to create three-dimensional scapula models with Mimics and Magics software. Bone holes in the anterior-inferior (3:00-6:00) position were assigned either to the non-perforated group if they were positioned entirely inside the glenoid bone or to the perforated group if the far cortex of the glenoid was penetrated by the drill. The angle between the glenoid articular surface and the bone hole was measured in the oblique coronal and transverse plane views. The length of the bone hole was also assessed. Of the 85 bone holes investigated, 42 were in the 3:00-6:00 position. Perforation was detected in 16 of these 42 holes (38.2%). The angle in the oblique coronal plane view and the length of the bone hole were significantly larger in the non-perforated group than in the perforated group; however, the angle in the transverse plane view did not significantly differ between the two groups. Before inserting an implant in the anterior-inferior area, the angle between the drill guide and the glenoid surface in the oblique coronal plane view should be carefully checked to ensure that the length of the hole inside the glenoid bone is adequate.

The role of topical application of bone morphogenetic protein 7 (BMP7) on bone healing on rabbits (Immunohistochemical study on TGF-β 3 & IGF-1R)

Background: Bone is essentially a highly vascular, living, constantly changing mineralized connective tissue. It is remarkable for its hardness, resilience and regenerative capacity, as well as its characteristic growth mechanisms. This study aimed to: 1. To evaluate the effect of bone morphogenetic protein7 (BMP7) on bone healing in artificially created intrabony defect in rabbits upper diastema, histologically. 2. To study the immunohistochemical expression of TGF-β3 and IGF-1R as bone formation markers in experimental and control groups during bone healing. Material and method: Forty male rabbits, was used in this study, 8 rabbits for each healing interval (3 days, 1,2 ,4 and 6 weeks). In each rabbit two bone holes were created on the right and left sides of the maxilla.BMP7 was applied to the bone hole in the left side while bone hole in the right left for normal healing. Routine processing and sectioning technique performed for histological evaluation. Immunohistochemical analysis utilized to localize the expression of TGF-β3 and IGF-1R in experimental and control groups for all animals. Results: Histological findings indicated that bone defect coated with BMP7 illustrated an early bone formation, mineralization and maturation in comparison to control group. Immunohistochemical findings revealed high positive expression for TGF-B3 and IGF-1R in experimental in comparison to control group. Conclusion: The study concluded that BMP7 protein enhance bone healing and maturation, also it regulate the expression of TGF-B3 and IGF1R in bone.

Medial Horizontal Suture Fixation of the Akin Osteotomy: A Technical Report

The Akin osteotomy is a complimentary procedure in hallux valgus surgery. Surgical techniques may vary depending on the operators or fixation devices. Suture fixation, for which a removal procedure is not necessary, can often be recommended. However, there is a risk of failure due to the thin cortex of the phalanx. We describe a new technique using Ethibond suture fixation in Akin osteotomy, which can lower the risk of phalangeal cortical failure and articular cartilage irritation. First, the Akin osteotomy was performed on the proximal phalanx 5 to 6 mm distal to the first metatarsophalangeal joint. Then bone holes were drilled from dorsum to plantar parallel to osteotomy with the Kirschner wire. The final procedure involved passing the Ethibond sutures connected to a straight needle through the holes and tying it. This fixation method offers an effective and easy technique for performance of Akin osteotomy.

Stereotactic Hematoma Removal of Spontaneous Intracerebral Hemorrhage through Parietal Approach.

ObjectiveTo determine the advantages of parietal approach compared to Kocher's point approach for spontaneous, oval-shaped intracerebral hemorrhage (ICH) with expansion to the parietal region.MethodsWe divided patients into two groups : group A had burr holes in the parietal bone and group B had burr holes at Kocher's point. The hematoma volume, Glasgow coma scale (GCS) score, and modified Barthel Index (mBI) score were calculated. At discharge, we evaluated the patients' Glasgow outcome scale (GOS) score, modified Rankin Scale (mRS) score, motor grade, and hospitalization duration. We evaluated the patients' mBI scores and motor grades at 6 months after surgery.ResultsThe hematoma volume in group A was significantly less than that in group B on postoperative days 1, 3, 5, 7, 14, and 21. Group A had significantly higher GCS scores than did group B on postoperative days 1 and 3. Group A had higher mBI scores postoperatively than did group B, but the scores were not significantly different. No differences were observed for the GOS score, mRS score, motor grade at discharge, or duration of hospitalization. The mBI score of group A at 6 months after surgery was significantly higher, and more patients in group A showed muscle strength improvement.ConclusionIn oval-shaped ICH with expansion to the parietal region, the parietal approach is considered to improve the clinical symptoms at the acute phase by removing the hematoma more effectively in the early stages. The parietal approach might help promote the long-term recovery of motor power.

Treatment of the terrible triad of the elbow using a single lateral incision (extensor digitorium communis split approach)

Objective To report the surgical techniques and results of treating the coronoid process and radial head fracture with dislocation of the elbow (terrible triad of the elbow) using a single lateral incision,the extensor digitorium communis (EDC) split approach.Methods A retrospective analysis was done of 23 patients with terrible triad of the elbow who had been treated by the authors from July 2011 to June 2013.They were 14 males and 9 females,with a mean age of 42.1 years (from 16 to 68 years).All patients were treated via a single lateral approach.The coronoid process was fixated by Kirschner wires combined with the anterior capsule suture lasso fixation.For the radial head fracture,14 cases were fixated by AO HCS and 9 cases by Acumed radial head replacement.In repair of the lateral collateral ligament complex and the common extensor tendon,6 cases used No.2 Ethibon suture through bone holes at the humeral lateral epicondyle,and the other 17 cases used suture anchors.No medial collateral ligament was repaired.Twenty patients were fixated by Stryker DJD Ⅱ hinged external fixator to protect the bone and soft tissue.Results All patients were followed up from 6 to 30 months (mean,19.0 months).The last follow-ups revealed that all patients recovered daily functions of the elbow with no need of secondary release.Their elbow flexion averaged 137.0° ± 8.8°,elbow extension-4.8° ± 15.0°,range of flexion and extension 132.2° ± 21.5°,forearm pronation 88.7° ± 6.3°,forearm supination 89.6° ± 2.1°,forearm rotation 178.3° ± 6.5°,and Mayo elbow performance score(MEPS) 97.4 ± 6.9 points.No obvious pain,instability,infection,or ulnar nerve symptoms was observed.Conclusions The elbow terrible triad with bone blocking can be treated by a simple lateral incision (the EDC split approach) to repair and fix the anterior capsule + coronoid process fracture,radial head fracture,and the lateral collateral ligament complex and the common extensor tendon.If the elbow is still unstable,it is advisable to add the hinged external fixator to protect the bone and soft tissue without repairing the medial structure by another incision,minimizing injury to the elbow,elbow stiffness and ulnar nerve lesions. Key words: Elbow joint; Fractures, bone; Dislocations; Radial head; Coronoid process

The influence of water jet diameter and bone structural properties on the efficiency of pure water jet drilling in porcine bone

Abstract. Using water jets in orthopedic surgery to drill holes in bones can be beneficial due to the absence of thermal damage and the always sharp cut. To minimize operating time and the volume of water that is used, the efficiency (volume of removed bone per added volume of water) of the water jet should be maximized. The goal was to study the effect of the open trabecular bone structure on the efficiency for different water jet diameters. 86 holes were drilled in porcine tali and femora submerged in water with nozzles of 0.3, 0.4, 0.5 and 0.6 mm at 70 MPa during 5 s and a standoff distance of 8 mm. MicroCT scans were made to measure the removed bone volume and the bone structural properties Trabecular Spacing (Tb.Sp.), Trabecular Thickness (Tb.Sp.) and Bone Volume Fraction (BV/TV). Pearson's correlation tests (p < 0.05, 95% confidence interval) were performed for each water jet diameter using the bone structural property as an independent factor and the efficiency as a dependent factor. No significant differences were found between the nozzle diameters in the material removal rates per added volume of water. The efficiency decreased for an increase in Tb.Th. and BV/TV for nozzles of 0.3, 0.4 and 0.5 mm. The 0.6 mm nozzle showed less influence of the Tb.Th. and BV/TV. The Tb.Sp. has no influence on the efficiency of a water jet. The total volume of added water combined with the Tb.Th. or BV/TV is a leading measure for the volume of bone material that is removed, which provides freedom in the development of water jet instruments as the nozzle diameter, pressure and jet time can be chosen in accordance to the maximum operating time requirements or dimensional limitations of a design.

Pharmacokinetics of Cefuroxime in Porcine Cortical and Cancellous Bone Determined by Microdialysis

Traditionally, the pharmacokinetics of antimicrobials in bone have been investigated using bone biopsy specimens, but this approach suffers from considerable methodological limitations. Consequently, new methods are needed. The objectives of this study were to assess the feasibility of microdialysis (MD) for measuring cefuroxime in bone and to obtain pharmacokinetic profiles for the same drug in porcine cortical and cancellous bone. The measurements were conducted in bone wax sealed and unsealed drill holes in cortical bone and in drill holes in cancellous bone and in subcutaneous tissue. As a reference, the free and total plasma concentrations were also measured. The animals received a bolus of 1,500 mg cefuroxime over 30 min. No significant differences were found between the key pharmacokinetic parameters for sealed and unsealed drill holes in cortical bone. The mean ± standard error of the mean area under the concentration-time curve (AUC) values from 0 to 5 h were 6,013 ± 1,339, 3,222 ± 1086, 2,232 ± 635, and 952 ± 290 min · μg/ml for free plasma, subcutaneous tissue, cancellous bone, and cortical bone, respectively (P < 0.01, analysis of variance). The AUC for cortical bone was also significantly different from that for cancellous bone (P = 0.04). This heterogeneous tissue distribution was also reflected in other key pharmacokinetic parameters. This study validates MD as a suitable method for measuring cefuroxime in bone. Cefuroxime penetration was impaired for all tissues, and bone may not be considered one distinct compartment.

Transsphenoidal surgery using a high definition video telescope for pituitary adenomas in dogs with pituitary dependent hypercortisolism: Methods and results

To (1) establish a technique for transsphenoidal removal of pituitary adenomas in dogs with pituitary dependent hypercortisolism (PDH) using a high definition video telescope, and (2) report initial outcomes. Prospective case series. Dogs with pituitary dependent hypercortisolism (PDH; n = 26) with suprasellar masses. Pituitary tumors were removed using a modification of a transoral transsphenoidal approach. Surgery was observed using a high definition video telescope (VITOM™) and localization of the sella was performed by drilling pilot holes in the basisphenoid bone followed by computed tomography (CT). Dogs had PDH confirmed by urinary cortisol to creatinine ratio (UCCR) and endogenous ACTH assays, and tumors confirmed by MRI. There were no postoperative cerebrospinal fluid leaks, wound dehiscence, or surgical site infections. Overall postoperative mortality was 19% with no mortality observed in the last 16 dogs, indicating an initial "learning curve" followed by good surgical results. All dogs that survived the immediate postoperative period (1 week) returned to their owners in good health, on hormonal replacement therapy. Follow-up ranged from 3 to 36 months. Sustained tumor control and hormonal remission based on normalized ACTH and UCCR measurements were observed in 20/21 (95%) dogs at 1-year follow-up. Modifications of a trans-oral transsphenoidal technique for surgical removal of pituitary tumors provides a safe and effective strategy for long-term remission of PDH with acceptable morbidity and mortality.

"Fat in the cerebellum": An unusual complication of occipitocervical fixation

Injuries to neural and vascular structures of the posterior fossa are the most dreaded complications of occipitocervical fi xation. We report an unusual complication of occipitocervical fi xation in a 38-year-old man, presenting with type III odontoid fracture, atlantoaxial instability, and quadriparesis; following a road traffic accident. Inadvertent dural tear occurred while drilling holes in the occipital bone for anchoring the implant. Postoperative imaging showed contusion and fat deposition in the cerebellum. Patient was managed withextraventricular drainage for the hydrocephalus and conservatively for the cerebellar lesion. Thorough search of literature showed no previous reports of such iatrogenic fat deposition within the cerebellum.

Zygomatic Surface Marker-Assisted Surgical Navigation: A New Computer-Assisted Navigation Method for Accurate Treatment of Delayed Zygomatic Fractures

To describe a new method of zygomatic surface marker navigation to treat delayed unilateral zygomatic fractures. The computed tomography (CT) data for 6 patients were obtained before surgery and imported into the surgical planning software. After 3-dimensional (3D) construction and segmentation, 3D cylindrical-shaped objects in stereolithographic format were placed in position and merged with the data from the fractured segments to mark the area for surface reduction. Data from the unaffected side were used to guide the reduction data for the segments with markers. During surgery, the surface markers were marked by drilling holes in the fractured bones in a process guided by the surgical navigation plan established before osteotomy. The segments were then reduced to the predetermined places using the positions of the hole markers as guides. 3D image comparisons and axial CT measurements were used to evaluate navigation accuracy and bone symmetry. Six patients with unilateral delayed zygomatic fractures were treated using this approach. The mean deviation between the postoperative 3D images and the reduction navigation plan for the 6 patients was +1.24 mm and -1.4 mm. The mean width deviation between the affected and unaffected sides was 1.28 mm, and the mean eminence deviation was 1.22 mm. All patients were followed up for at least 3 months and experienced no obvious complications. Zygomatic surface marker-assisted surgical navigation can simplify the navigation planning for surgery and avoid the complex protocols needed to create the surgical templates. The navigation accuracy was acceptable, and all 6 patients obtained good facial symmetry.

Robotized System for Bone Drilling and Cutting in Orthopedic Surgery

Bone drilling and cutting manipulations are widespread in the orthopedic surgery. In free hand performance of them some errors such as an inaccurate penetration and dilate of bone hole, overheating, harm soft tissues could be occurring. The goal of this study is to design and develop control concept for a bone drilling and cutting robotized system. The proposed orthopedic system consists of two executive modules for drilling and cutting and common control panel. The control algorithms and programs for drilling have done and given in the paper. We are developing the control algorithms for cutting manipulation.

Pure Waterjet Drilling of Articular Bone: An in vitro Feasibility Study

The clinical application of waterjet technology for machining tough human tissues, such as articular bone, has advantages, as it produces clean sharp cuts without tissue heating. Additionally, water supply is possible via flexible tubing, which enables minimally invasive surgical access. This pilot study investigates whether drilling bony tissue with pure waterjets is feasible. Water pressures between 20 and 120 MPa with an orifice of 0.6 mm were used to create waterjets to drill blind borings in the talar articular surface of cadaveric calcaneus bones of human, sheep, goats and pigs. A stand-off distance between 2.5 and 5.5 mm and a jet-time of 5 seconds were chosen. The depth of the holes was measured using a custom-adapted dial gauge. At least 30 MPa of water pressure is required to penetrate the human and goat specimens, and 50 MPa for the pig and sheep specimens. Overall, the machined holes were conically shaped and increased in depth with an increase of pressure. Above certain pressure levels, pure waterjets can be used for machining holes in articular bone, thereby opening a window for further research on pure waterjet drilling in orthopedics.

Salvaging the Pullout Strength of Stripped Screws in Osteoporotic Bone

Our goal was to determine whether the pullout strength of stripped screw holes in osteoporotic bone could be increased with readily available materials from the operating room. We inserted 3.5-mm stainless steel nonlocking self-tapping cortical screws bicortically into 5 osteoporotic humeri. Each screw was first stripped by rotating it 1 full turn past maximum torque. In the control group, the screw was pulled out using an MTS machine (858; MTS Inc, Eden Prairie, Minnesota). In the treatment groups, the screw was removed, the hole was augmented with 1 of the 3 materials (stainless steel wire, polysorb suture, or polyethylene terephthalate glycol plastic sheet), and the screws were replaced and then pulled out. The effect of material on pullout strength was checked for significance (P < .05) using a general linearized latent and mixed model (Stata10; StataCorp, College Station, Texas). The mean (95% confidence interval) pullout strength for the unaugmented hole was 138 N (range 88-189), whereas the holes augmented with plastic, suture, or wire had mean pullout strengths of 255 N (range 177-333), 228 N (range 149-308), and 396 N (range 244-548), respectively. Although wire augmentation resulted in pullout strength that was significantly greater than that of the unaugmented screw, it was still below that of the intact construct.

Islet Transplantation in a Subarachnoid Cavity Surrounding Olfactory Bulb of Diabetic Rats

Islet Transplantation in a Subarachnoid Cavity Surrounding Olfactory Bulb of Diabetic Rats

Characterization of Initial Microfracture Defects in Human Condyles

Microfracture (MFX) is a cartilage repair technique that depends on cell migration from marrow-rich trabecular bone cavities into the cartilage lesion. This study tested the hypothesis that MFX awls with distinct geometry generate different hole shapes and variable bone marrow access in condyles with Grade III to IV lesions. Lateral and medial condyles from total knee arthroplasty (N = 24 male and female patients, 66 ± 9 years) were systematically microfractured ex vivo to 2 and 4 mm deep and the bone holes analyzed by micro-computed tomography. Subchondral bone in lesional condyles showed different degrees of sclerosis up to 2 mm deep ("porous," sclerotic, extremely dense). MFX holes ranged from 1.1 to 2.0 mm in diameter, and retained the awl shape with evidence of slight bone elastic rebound and bone compaction lining the holes that were increased by wider awl diameter and deeper MFX. Marrow access was significantly diminished by sclerosis for all three awls, with an average marrow access varying from 70% (nonlesional bone) to 40% (extremely dense bone). This study revealed that subchondral bone sclerosis can reach a critical limit beyond which MFX creates bone compaction and fissures instead of marrow access.

Negative pressure technology enhances bone regeneration in rabbit skull defects

BackgroundBone is a slowly regenerating tissue influenced by various physiological processes, including proliferation, differentiation, and angiogenesis, under the control of growth factors. Shortening this healing time is an important and popular clinical research focus in orthopedics. Negative pressure can stimulate angiogenesis, improve blood circulation, promote granulation tissue growth and accelerate tissue wound healing. We sought to determine whether negative pressure could reduce bone healing time in a rabbit cranial defect model.MethodsFour symmetrical holes (diameter, 3.5 mm) were drilled into the skulls of 42 New Zealand white rabbits, with two holes in each parietal bone. For each rabbit, the two sides were then randomly assigned into experimental and control groups. Using negative pressure suction tubes, experimental holes were treated with −50 kPa for 15 minutes, four times per day, whereas the control holes remained untreated. After 4 weeks, the negative pressure suction tubes were removed. At 2, 4, 6 and 8 weeks, three-dimensional (3D) reconstruction computed tomography (CT), X-ray radiopacity, and two-photon absorptiometry were used to evaluate new bone formation. Histological changes were determined by hematoxylin and eosin (H.E) staining. At weekly intervals until 6 weeks, the mRNA expression levels of vascular endothelial growth factor (VEGF) and bone morphogenetic protein (BMP)-2 were evaluated by RT-PCR. A paired student’s t-test was employed to compare X-ray radiopacity and bone density measurements between the experimental and control groups.Results3D-reconstruction CT showed that new bone regeneration in the experimental group was greater than that in the control group at 4 and 6 weeks. At these time points, the experimental group presented with higher X-ray radiopacity and increased bone density (P < 0.05) as compared with the control group. Cartilage islands and new bone were observed by H.E staining at 2 weeks in the experimental group. By 6 weeks, the new bone had matured into lamellar bone in the experimental group. RT-PCR results showed that VEGF and BMP-2 were highly expressed in the experimental group as compared with control.ConclusionsIntermittent negative pressure can promote the regeneration of bone possibly by enhancing the expression of VEGF and BMP-2.