Assessment Of Bone Healing Research Articles

Imaging Modalities to Assess Fracture Healing.

This review discusses imaging modalities for fracture repair assessment, with an emphasis on pragmatic clinical and translational use, best practices for implementation, and challenges and opportunities for continuing research. Semiquantitative radiographic union scoring remains the clinical gold standard, but has questionable reliability as a surrogate indicator of structural bone healing, particularly in early-stage, complex, or compromised healing scenarios. Alternatively, computed tomography (CT) scanning enables quantitative assessment of callus morphometry and mechanics through the use of patient-specific finite-element models. Dual-energy X-ray absorptiometry (DXA) scanning and radiostereometric analysis (RSA) are also quantitative, but technically challenging. Nonionizing magnetic resonance (MR) and ultrasound imaging are of high interest, but require development to enable quantification of 3D mineralized structures. Emerging image-based methods for quantitative assessment of bone healing may transform clinical research design by displacing binary outcomes classification (union/nonunion) and ultimately enhance clinical care by enabling early nonunion detection.

Ultrasonic evaluation of bone health in patients

Noninvasive and quantitative methods for evaluation of bone health are of interest in clinical practice. Two areas of particular interest include evaluation of bone fracture healing and assessment of osteoporosis. Determination of bone healing time impacts patient health and the associated economic factors. Furthermore, assessment of bone quality in patients at risk for osteoporosis/osteopenia can benefit a large number of patients in the upper age group. Here, we present a quantitative method for the evaluation of bone integrity and quality. This method is based on analyzing the acoustic response of bone to stimulation provided by the acoustic radiation force of ultrasound. Longitudinal studies for bone healing assessment were conducted on a group of patients with clavicle fracture. The contralateral intact bone was used as a control for each patient. Bone healing assessments were performed using mode decomposition. It was found that the healing process could be detected in 80% of fractured bones. A separate study was conducted to differentiate osteoporotic/osteopenic from normal bones. A total of 27 adult volunteers in two groups of healthy and those with osteopenia/osteoporosis were tested. Results of the test on tibia showed that osteoporosis/osteopenia bones could be differentiated from the healthy ones (<2 × 10-5).

Radiographic Assessment of Bone Healing Using Cone-beam Computed Tomographic Scans 1 and 5 Years after Apical Surgery

IntroductionThe objective of this long-term study was to evaluate radiographic healing in cone-beam computed tomographic (CBCT) scans taken 1 and 5 years after apical surgery. MethodsIn the context of a prospective clinical study, postsurgical CBCT scans were taken 1 and 5 years after apical surgery. Three calibrated observers independently assessed buccolingual CBCT images oriented along the longitudinal axis of the treated roots. Radiographic periapical healing was categorized as “fully, partially, or not healed” for each of the following study parameters: the resection plane, the cortical plate, the apical area, and the overall bone healing. The analysis included the interobserver agreement (Fleiss kappa values), the comparison of 5- and 1-year ratings, and the changes of healing categories from 1–5 years (McNemar-Bowker tests). Data were analyzed statistically for the detection of significant differences. ResultsCBCT images of 41 teeth (in 41 patients) with 47 treated roots were evaluated. At 5 years, all studied parameters had higher rates of fully healed cases compared with the rate at 1 year. The resection plane and apical area parameters each were judged in 72.3% as fully healed at 5 years, whereas the cortical plate and overall bone healing parameters showed clearly lower fully healed rates (42.6% and 38.3%, respectively). Fully healed cases at 1 year remained so at 5 years in 87.5%–100% depending on the study parameter. ConclusionsThis 5-year CBCT follow-up study of apical surgery showed a marked improvement of radiographic healing from 1–5 years but to a varying degree regarding the different study parameters. Although new hard tissue formation at the resection plane and within the former apical defect was advanced in most cases at 5 years, the reestablishment of the cortical bone plate clearly lagged behind.

55: Bone Regeneration Assessment Through SPECT/CT Imaging in a Mouse Calvarial Defect Model

Introduction The evaluation of novel synthetic bone implants relies mostly on histological examination, but as bone repair takes several weeks, non-invasive imaging techniques have gained interest in the recent past. Ιn the frame of this study, we establish a SPECT/CT imaging protocol for the longitudinal assessment of bone healing of a calvarial mouse defect model using mineralized collagen-based scaffolds. Materials and Methods Two symmetrical calvarial bone defects, 1.5 mm in diameter each, were created in female Swiss mice. Gaps were monitored weekly through SPECT/CT imaging (γ-CUBE, X-CUBE, Molecubes, providing a resolution of 0.6 mm and 0.05 mm, respectively), using [99mTc]-MDP for 5 weeks. Defects created on the left part of the mouse skull were left unfilled (control group), whereas those on the right part were filled with mineralized horse collagen scaffold materials (HA/Coll). Results and Discussion: The monitoring of bone healing was successfully and accurately performed via SPECT/CT imaging. CT imaging showed the actual bone filling process and the formation of new bone tissue, whereas SPECT imaging provided the increased metabolic activity. For the HA/Coll treated defect, a peak in metabolic activity was noted at week 1 post-surgery and the defect was filled by newly developed bone tissue by week 3 post-surgery (Figure 1). In contrast, the metabolic activity at the control defect area was stable but significantly lower and a complete healing was not observed even up to week 5post-surgery. These results show that combined SPECT/CT imaging can provide an accurate tool for bone healing monitoring. CT is a high resolution tool for new bone formation control and SPECT is a high sensitivity tool for early metabolic activity confirmation, also having a high prognostic value for bone healing. Conclusions SPECT revealed the earliest signs of new bone tissue formation due to the increased metabolic activity and CT provided a clear visualization and quantification ability of the healing process over time. This study is part of the EU Horizon 2020 research and innovation VIVOIMAG project under the Marie Skłodowska-Curie grant agreement No 645757. This study was co-supported through the Programme of Industrial Scholarships of Stavros Niarchos Foundation. Figure 1. Indicative axial CT (a), sagittal SPECT/CT (b) and axial SPECT/CT (c) at 3 h [99m]Tc-MDP post-injection (~2 mCi) of a bilateral calvarial mouse defect treated (HA/Coll) and non-treated (control), at week 1 (first row) and at week 3 (second row) post-surgery.

Assessment of bone healing after mineral trioxide aggregate and platelet-rich fibrin application in periapical lesions using cone-beam computed tomographic imaging.

The aim of this study was to compare the effects of mineral trioxide aggregate (MTA) and platelet-rich fibrin (PRF) use on periapical healing in surgically treated periapical lesions using three-dimensional (3D) cone-beam computed tomographic (CBCT) imaging. A total of 40 periapical lesions undergoing apical surgery were selected between December 2016 and November 2017. The participants were randomly divided into four study groups: control, MTA, PRF, and MTA+PRF. No interventions were made in the control group except root-end resection. Routine radiographs were taken in the 3rd, 6th, and 12th months. The volume and density of periapical lesions at the 1-year follow-up were compared with the pre-op values using the MIMICS software program. Primary healing of the periapical tissues was evaluated, and the outcomes were noted. Post-op volume values were significantly decreased, and density values were significantly increased according to the pre-op measurements. In the post-op volume evaluation between the groups, significant differences were observed in the MTA and MTA+PRF groups compared with the control group (p < 0.005). However, no substantial significance was noted between the control and PRF groups. There were no significant differences in post-op density calculations between all groups. High success rates were achieved using MTA in periapical lesions in endodontic microsurgery. The application of PRF to the surgical cavity may not necessarily improve outcomes. Further studies are needed with long-term follow-up. NCT03743987 (The Effect of MTA and PRF Application in Periapical Lesions).

Virtual structural analysis of tibial fracture healing from low-dose clinical CT scans

Quantitative assessment of bone fracture healing remains a significant challenge in orthopaedic trauma research. Accordingly, we developed a new technique for assessing bone healing using virtual mechano-structural analysis of computed tomography (CT) scans. CT scans from 19 fractured human tibiae at 12 weeks after surgery were segmented and prepared for finite element analysis (FEA). Boundary conditions were applied to the models to simulate a torsion test that is commonly used to access the structural integrity of long bones in animal models of fracture healing. The output of each model was the virtual torsional rigidity (VTR) of the healing zone, normalized to the torsional rigidity of each patient’s virtually reconstructed tibia. This provided a structural measure to track the percentage of healing each patient had undergone. Callus morphometric measurements were also collected from the CT scans. Results showed that at 12 weeks post-op, more than 75% of patients achieved a normalized VTR (torsional rigidity relative to uninjured bone) of 85% or above. The predicted intact torsional rigidities compared well with published cadaveric data. Across all patients, callus volume and density were weakly and non-significantly correlated with normalized VTR and time to clinical union. Conversely, normalized VTR was significantly correlated with time to union (R2 = 0.383, p = 0.005). This suggests that fracture scoring methods based on the visual appearance of callus may not accurately predict mechanical integrity. The image-based structural analysis presented here may be a useful technique for assessment of bone healing in orthopaedic trauma research.

ASSESSMENT OF HUMAN DENTAL PULP STEM CELLS WITH CHITOSAN SCAFFOLD VERSUS XENOGRAFTS IN IMPLANT OSSEOINTEGRATION. AN EXPERIMENTAL STUDY IN A RABBIT MODEL

Background: Human dental pulp stem cells (hDPSCs) considered as a promising source of mesenchymal stem cells for bone regeneration. It can be used to improve osseointegration of dental implant and improve its stability. Objectives: Assessment of bone healing and implant osseointegration by the use of human dental pulp stem cells with chitosan scaffold and compared the result with xenografts in a rabbit model. Materials &Methods: Eighteen adult white rabbits were used in this study. They were distributed equally into three groups, group I, human dental pulp stem cells and chitosan was used before implant insertion in the tibia. Group II, xenografts were used and group III was the control group. After 12 weeks the animals were sacrificed and assessment of bone formation was accomplished by the used of the histological section using H&E, Masson stain as well as scanning electron microscope (SEM). Results: The highest mean area percent was detected in the stem cell group, followed by the xenograft group, while the control group revealed the lowest mean area percent value. Analysis of variance test revealed a highly significant difference between the studied groups (P=0.00). Comparison between the gap distances (µm) in the three groups measured by electron microscope indicated that the lowest mean gap distance was presented in the stem cells group. Conclusion: human dental pulp stem cells coupled with chitosan is a promising method for bone formation and maturation around dental implant and help in osseointegration.

Comparison of bone healing and outcomes between allogenous bone chip and hydroxyapatite chip grafts in open wedge high tibial osteotomy.

Allogenous bone chips and hydroxyapatite (HA) chips have been known as good options for filling an inevitable void after open wedge high tibial osteotomy (OWHTO). However, there are concerns regarding bone healing after the use of these grafts. The purpose of this study was to compare the bone healing represented by the osteoconductivity and absorbability between allogenous bone chips and HA chips in OWHTO. The outcomes of bone healing of 53 patients who received an allogenous bone chip graft and 41 patients who received an HA chip graft were retrospectively evaluated, and the results were compared between the two groups. Osteoconductivity and absorbability were serially evaluated for the assessment of bone healing at 6 weeks, 3 months, 6 months, and 1 year postoperatively. The osteoconductivity of the allogenous bone chips was greater than that of the HA chips at 6 weeks postoperatively (p < 0.05). However, there were no statistically significant differences from 3 months to 1 year postoperatively. The absorbability showed no statistically significant differences 6 weeks and 3 months after OWHTO; however, the allogenous bone chip group showed a greater absorbability at 6 months and 1 year postoperatively (42.8 ± 14.2 vs. 34.6 ± 13.8, p = 0.006 at 6 months postoperatively; 54.6 ± 14.4 vs. 43.0 ± 14.0, p < 0.001 at 1 year postoperatively). However, the two graft materials showed similar results of HKA angle, WBL ratio, posterior tibial slope.

Ultrasound Assessment of Bone Healing after Root-end Surgery: Echoes Back to Patient's Safety

IntroductionThe aim of this study was to present ultrasound imaging (UI) techniques as promising and safe tools for the follow-up of root-end surgery (RES) in vivo. MethodsThe study included 8 patients who underwent RES. All were followed up using UI at 1 week, 1 month, 2 months, 3 months, and 6 months (if necessary) after RES. The bony crypt was defined on the ultrasound image, and the following observations were made during follow-up: cortical bone interruption and surface area measurement of the residual echoic bony crypt image. ResultsIn all cases, the hypoechoic image became hyperechoic, indicating gradual bone healing of the crypt. Compared with baseline, at 3 months a remaining cortical opening of 51.2% (±12.6%) and a bony crypt surface area of 24.3% (±10.8%) was detected for all patients. For 50% of the patients, the echographic follow-up ended at 3 months because the ultrasound waves could no longer enter the bony crypt. For 4 patients who attended the 6-month recall, a remaining cortical disruption of 43.2% (±9.9%) and a bony crypt surface area of 17.2% (±7%) compared with the baseline was noted. ConclusionsUI is a promising follow-up tool for RES. It helps clinicians understand the initial stages of bone healing, allows close healing monitoring, and is radiation free.

An electronically instrumented internal fixator for the assessment of bone healing.

ObjectivesThe monitoring of fracture healing is a complex process. Typically, successive radiographs are performed and an emerging calcification of the fracture area is evaluated. The aim of this study was to investigate whether different bone healing patterns can be distinguished using a telemetric instrumented femoral internal plate fixator.Materials and MethodsAn electronic telemetric system was developed to assess bone healing mechanically. The system consists of a telemetry module which is applied to an internal locking plate fixator, an external reader device, a sensor for measuring externally applied load and a laptop computer with processing software. By correlation between externally applied load and load measured in the implant, the elasticity of the osteosynthesis is calculated. The elasticity decreases with ongoing consolidation of a fracture or nonunion and is an appropriate parameter for the course of bone healing. At our centre, clinical application has been performed in 56 patients suffering nonunion or fracture of the femur.ResultsA total of 39 cases of clinical application were reviewed for this study. In total, four different types of healing curves were observed: fast healing; slow healing; plateau followed by healing; and non-healing.ConclusionThe electronically instrumented internal fixator proved to be valuable for the assessment of bone healing in difficult healing situations. Cost-effective manufacturing is possible because the used electronic components are derived from large-scale production. The incorporation of microelectronics into orthopaedic implants will be an important innovation in future clinical care.Cite this article: B. Kienast, B. Kowald, K. Seide, M. Aljudaibi, M. Faschingbauer, C. Juergens, J. Gille. An electronically instrumented internal fixator for the assessment of bone healing. Bone Joint Res 2016;5:191–197. DOI: 10.1302/2046-3758.55.2000611.

Extending structural health monitoring concepts for bone healing assessment

AbstractA series of experimental investigations are performed to show the potential of integrating sensing elements into an external fixation for healing assessment of a fracture femur. This investigation is supported by finite element analyses that highlight the fundamental structural dynamics, which enable a stiffness‐based healing assessment methodology. A saw‐bone femur externally fixated with a Hoffman II will be subjected to an artificial fracture. The healing of the fractured femur is simulated with the curing of epoxy applied to the fractured region. The finite element analyses results will help determine the useful modes for assessing the state of healing of the fracture that can be attributed to the changes in the stiffness of the fixated structure. The findings will be tested against a set of experiments to show how the stiffness‐related quantities can be delineated from the dynamic response. The results reported will show distinct changes to the frequency response functions as the epoxy cures demonstrating the potential of integrating sensors onto an external fixation for healing and fracture union assessment.

Modern Radiological Postoperative Diagnostics of the Hip Joint in Children and Adults.

The assessment of bone healing and loosening of endoprosthesis material was long the primary indication for postoperative projection radiography and CT imaging of the hip joint following trauma and endoprosthesis implantation. With the increasing number of joint-preserving surgery, e. g. of surgical hip luxation and hip arthroscopy for the treatment of femoroacetabular impingement (FAI), high-resolution imaging of intra-articular pathologies before and after surgery has become increasingly important. In this review article, diagnostic imaging of the hip joint is presented following common trauma surgery and orthopedic surgery interventions. The imaging modalities of projection radiography, CT and MRI including direct MR-arthrography are discussed with regard to their diagnostic capability in the postoperative assessment of the hip joint. Among others topics, imaging is discussed following hip arthroplasty, following surgical hip luxation and arthroscopic interventions for the treatment of FAI, as well as following core decompression for avascular necrosis of the femoral head. Moreover, orthopedic interventions of the hip joint in children and adolescents are presented and the dedicated reporting of postoperative imaging is outlined. • Consolidation of osteotomies and position of implants should be assessed in postoperative imaging. • MRI is useful for confirming correct articulation after treatment of congenital hip dislocation. • Radiologically assessable complications after total hip replacement are inlay wear, loosening, dislocation, periarticular ossifications and infection. • MRI can detect and classify pseudotumours in cases of metal-metal pairing after total hip replacement.

Assessment of bone healing around immediately loading dental implants in posterior maxilla with two different osteotomy techniques

The posterior region of the maxilla is characterized by thin cortical bone and trabecular bone of low-density. In addition, in many instances the height of the bone in this region is insufficient to achieve high primary stability because of the presence of the maxillary sinus. The aim of this study was to assess bone healing around immediately loaded dental implants in the posterior maxillary region with two different osteotomy techniques, conventional technique versus condensing technique. Twenty implants were inserted in 10 patients each patient received 2 implants. One implant was inserted by a conventional technique other implant was inserted by condensing technique one on each side of the maxilla. The follow-up was done at the following intervals, immediate postoperative, 6-, 12-, and 24-week. One implant from the group of condensing technique showed failure after 4 weeks. The results of this research demonstrate the success rate was 90% for condensing group and 100% for the conventional group.

Cleft palate reconstruction using collagen and nanofiber scaffold incorporating bone morphogenetic protein in rats.

Absorbable collagen sponge (ACS) loaded with bone morphogenetic protein-2 (BMP-2) is approved for selected clinical applications; however, burst release limits its widespread use. Therefore, nanofiber (NF)-based scaffold with ACS backbone was developed to sustain release of loaded BMP-2 to improve the outcomes of bone grafting in a rodent model of cleft palate. BMP-2 was loaded on ACS scaffold and then NF hydrogel with different densities (1-2%) was added to sustain the BMP-2 release. The release profiles of BMP-2 from constructs with different NF densities were evaluated in vitro to explore the optimum NF density that could recapitulate physiological bone healing process. Subsequently, scaffold with the appropriate NF density was implanted into a rodent model of cleft palate. Wistar rats, with surgically induced maxillary cleft defects, were then assigned to one of the following groups (n=6/group): no scaffold (control), ACS, ACS+BMP-2, NF+ACS, and NF+ACS+BMP-2. Micro-computed tomography (μCT) was utilized to evaluate percent bone filling (%BF) at defect site as well as changes in anteroposterior and transverse dimensions of the maxilla at weeks 0, 4, and 8. Histological assessment of bone healing was performed at week 8. In vitro release experiments showed that scaffolds containing 2% NF exhibited a release profile conducive to the natural stages of bone healing and, hence, it was utilized for subsequent in vivo studies. Bone healing occurred at the defect margins leaving a central bone void in the control, ACS, and NF+ACS groups over the 8-week study period. BMP-2-treated groups demonstrated higher %BF as compared with other groups at week 8 (p<0.05). Whereas the NF+ACS+BMP-2 group showed bone bridging of the defect as early as 4 weeks, which was not evident in ACS+BMP-2 group. In all groups, bone grafts did not disrupt anteroposterior and transverse growth of maxilla. Based on histological evaluations together with μCT data, NF+ACS+BMP-2 treatment resulted in clinically significant and consistent bone healing throughout the implanted scaffold when compared with the ACS+BMP-2 group. NF+ACS+BMP-2 constructs exhibited osteoinductive properties together with preparation simplicity, which makes it a novel approach for BMP-2 delivery for cleft palate reconstruction.

Validation of the use of radiographic fracture-healing scores in a small animal model.

Precise assessment of fracture-healing is vital in both clinical and research settings, where therapies are typically assessed using animal models with union as the study end point. Radiographic scoring systems have been developed for clinical use; however have not been validated in pre-clinical models. Thirty sets of radiographs of rat tibial shaft fractures, treated with external fixation were reviewed by six observers using the Radiographic Union in Tibia (RUST) scale, the Lane & Sandhu score, and an overall impression of union. Fleiss's kappa and Intra-class Correlation Coefficients (ICC) were used to determine reliability. Inter-observer and intra-observer agreement using the general impression score were moderate [kappa; 0.58; 95%CI (0.49-0.65) and 0.66 (0.43-0.89), respectively]. Inter-observer and intra-observer agreement were excellent using both the RUST score [ICC; 0.81 (0.72-0.89) and 0.86 (0.74-0.93), respectively], and Lane & Sandhu score [ICC; 0.88 (0.81-0.93) and 0.90 (0.81-0.95), respectively]. Employing a defined scoring system enhances both the reproducibility and repeatability of bone healing assessment in a small animal model. Routine reporting of fracture scoring methodology should be encouraged to enrich results and facilitate data synthesis across studies.

The effect of bone membrane on secretion of BMP-2 and bone healing in a rabbit model of bone defect

Objective To investigate the effect of bone membrane on secretion of bone morphogenetic protein-2(BMP-2) and bone healing in a rabbit model of bone defect.Methods Forty-eight New Zealand rabbits (4 months old,half male and half female) were randomly divided into 2 equal groups (n =24).A 0.5 cm bone defect of middle radius was created operatively under anesthesia in all the animals.The bone membrane around the defect was preserved in group A but exsected in group B.Six rabbits in each group were sacrificed each time at immediate,1,3 and 4 weeks post-operation.X-ray films of the bone defects were taken,gross observation of the tissue samples from the defect site was made,and semiquantitative detection of BMP-2 content by Western blotting was conducted at each time point.Quantitative assessment of bone healing was performed using Lane-Sandhu X-ray evaluation system.Results In group A,the amount of BMP-2 increased gradually at l,3,4 weeks postoperation,significantly higher than that at immediate postoperation (P ＜ 0.05).In group B,the amount of BMP-2 peaked at one week postoperation,significantly higher than that at immediate postoperation (P ＜ 0.05).At one week postoperation,there was no significant difference between the 2 groups in the amount of BMP-2 (P ＞ 0.05).At 3 and 4 weeks postoperation,the amount of BMP-2 in group A was significantly higher than in group B (P ＜ 0.05) and the mean Lane-Sandhu X-ray score in group A was also significantly higher than in group B (P ＜ 0.05).Conclusion Since preservation of bone membrane increases secretion of BMP-2 and promotes bone healing in the healing process of bone defect,we should try to preserve bone membrane when bone defects are treated. Key words: Bone morphogenetic proteins; Bone membrane; Bone healing; Bone defect

Recombinant Human BMP-2 Increases the Incidence and Rate of Healing in Complex Ankle Arthrodesis

Although its FDA-approved applications are limited, the pro-osteogenic benefits of recombinant human BMP-2 (rhBMP-2) administration have been shown in off-label surgical applications. However, the effects of rhBMP-2 on ankle fusions are insufficiently addressed in the literature, which fails to include a case-control study of adequate sample size to evaluate the efficacy of rhBMP-2 treatment. In this study we asked whether rhBMP-2 treatment (1) would increase the rate of successful ankle fusion in complex patients (patients with comorbidities associated with poor surgical healing) compared with a control group of patients undergoing ankle fusion who did not receive rhBMP-2; (2) would reduce total time wearing a frame when compared with the control group; (3) would result in a difference in the percentage of bone bridging between the group treated with rhBMP-2 and the control group, as determined by CT scans 3 months after surgery; and (4) would encounter an equal rate of complications different from untreated patients. A retrospective chart study was performed on 82 patients who, because of a host of comorbidities associated with poor healing, required a complex ankle arthrodesis with the Ilizarov technique. The first 40 patients did not receive rhBMP-2, whereas the subsequent 42 patients received intraoperative rhBMP-2. Time wearing the frame was determined by chart review; decision to remove the frame was made by the surgeon based on quantitative bone bridging measured using a CT scan taken 3 months after fusion. Patients treated with rhBMP-2 were more likely to obtain fusion after the initial surgery (93% versus 53%, p < 0.001; OR, 11.76; 95% CI, 3.12-44.41), spent less total time wearing the frame (124 versus 161 days, p < 0.01), and showed more bone bridging on CT scans (48% versus 32%, p < 0.05). All patients with greater than 30% bone bridging observed on CT scans 3 months postoperatively achieved successful union without further intervention. Our findings suggest that rhBMP-2 is a beneficial adjunct for selected groups of patients undergoing complex ankle arthrodesis. CT is a promising modality in the assessment of bone healing in ankle fusion. A proper randomized controlled trial remains necessary to fully describe the efficacy of rhBMP-2 in accelerating bone healing.

In Vivo Assessment of Bone Healing following Piezotome® Ultrasonic Instrumentation

This pilot study evaluated the molecular, histologic, and radiographic healing of bone to instrumentation with piezoelectric or high speed rotary (R) devices over a 3-week healing period. Fourteen Sprague-Dawley rats (Charles River Laboratories International, Inc., Wilmington, MA, USA) underwent bilateral tibial osteotomies prepared in a randomized split-leg design using Piezotome® (P1) (Satelec Acteon, Merignac, France), Piezotome 2® (P2) (Satelec Acteon), High-speed R instrumentation, or sham surgery (S). At 1 week, an osteogenesis array was used to evaluate differences in gene expression while quantitative analysis assessed percentage bone fill (PBF) and bone mineral density (BMD) in the defect, peripheral, and distant regions at 3 weeks. Qualitative histologic evaluation of healing osteotomies was also performed at 3 weeks. At 1 week, expression of 11 and 18 genes involved in bone healing was significantly (p < .05) lower following P1 and P2 instrumentation, respectively, relative to S whereas 16 and 4 genes were lower relative to R. No differences in PBF or BMD were detected between groups within the osteotomy defect. However, significant differences in PBF (p = .020) and BMD (p = .008) were noted along the peripheral region between P2 and R groups, being R the group with the lowest values. Histologically, smooth osteotomy margins were present following instrumentation using P1 or P2 relative to R. Piezoelectric instrumentation favors preservation of bone adjacent to osteotomies while variations in gene expression suggest differences in healing rates due to surgical modality. Bone instrumented by piezoelectric surgery appears less detrimental to bone healing than high-speed R device.

Total hip arthroplasty for acetabular protrusion combined with shortening of femoral head and neck

Objective To evaluate the operative techniques and clinical outcomes of total hip arthroplasty (THA) for acetabular protrusion combined with shortening of femoral head and neck.Methods From August 2008 to March 2012,15 patients (17 hips) with acetabular protrusion combined with shortening of femoral head and neck were treated with THA.They were 6 males (6 hips) and 9 females (11 hips),aged from 21 to 68 years (average,45.6 years).According to Dunlop' s criteria,the acetabular protrusion was mild in one hip,moderate in 11 hips and severe in 5 hips.Mild shortening was present in 5 hips,moderate shortening in 8 hips and severe shortening in 4 hips.The acetabular walls were rasped respectively.Auto-bone grafting was impacted on the acetabular bottom to recover the acetabular center of rotation and cementless prostheses were planted with press-fit skills.The hip capsule and surrounding soft tissues were released after reduction of the hip.At regular follow-ups,hip functions were evaluated by Harris scores and roentgenographic assessment of bone healing at the prosthesis-bone interface was performed according to Engh' s description.Results The mean follow-up was 28.5 months (range,from 10 to 46 months).Biologic press-fit of the acetabulum and femoral component was achieved in all hips immediately after operation.Massive bone ingrowth was acquired for bony stabilization at 3 months postoperatively on X-ray.No prosthetic loosening or re-protrusion was observed at the last follow-up.The mean Harris score improved from preoperative 43.1 ± 4.8 points to 91.2 ± 5.2 points at the 6-month follow-up,and remained 92.5 ± 3.1 points at the last follow-up.There were significant differences between preoperation and 6 months post-operation and the last follow-up respectively (P ＜ 0.05).Conclusions Acetabular protrusion combined with shortening of femoral head and neck can be effectively treated by THA.The key operative techniques are hip reduction with a short head and neck model,and gradual releasing of the contracture of hip capsule and surrounding soft tissues while a sufficient tension is maintained at the hip joint. Key words: Arthroplasty, replacement, hip; Acetabulum; Femoral head; Shortening

Mechanical Property Assessment of Bone Healing around a Titanium–Zirconium Alloy Dental Implant

It has been reported that titanium-zirconium alloy with 13-17% zirconium (TiZr1317) implants show higher biomechanical stability and bone area percentage relative to commercially pure titanium (cpTi) grade 4 fixtures. This study aimed to determine whether the higher stability for TiZr1317 implants is associated with higher mechanical properties of remodeling bone in the areas around the implants. This study utilized 36 implants (n = 18: TiZr1317, n = 18: cpTi), which were placed in the healed ridges of the mandibular premolar and first molar of 12 mini pigs (n = 3 implants/animal). After 4 weeks in vivo, the samples were retrieved, and resin-embedded histologic sections of approximately 100 μm in thickness were prepared. In order to determine the nanomechanical properties, nanoindentation (n = 30 tests/specimen) was performed on the bone tissue of the sections under wet conditions with maximum load of 300 μN (loading rate: 60 μN/s). The mean (± standard deviation) elastic modulus (E) and hardness (H) for the TiZr1317 group were 2.73 ± 0.50 GPa and 0.116 ± 0.017 GPa, respectively. For the cpTi group, values were 2.68 ± 0.51 GPa and 0.110 ± 0.017 GPa for E and H, respectively. Although slightly higher mechanical properties values were observed for the TiZr1317 implants relative to the cpTi for both elastic modulus and hardness, these differences were not significant (E = p > 0.75; H = p > 0.59). The titanium-zirconium alloy used in this study presented similar degrees of nanomechanical properties to that of the cpTi implants.