Bone Block Research Articles

A Biomechanical Analysis of the Influence of the Morfology of the Bone Blocks Grafts on the Transfer of Tension or Load to the Soft Tissue by Means of the Finite Elements Method.

Edentulism produces resorption of alveolar bone processes, which can complicate placement of dental implants. Guided bone regeneration techniques aim to recover the volume of bone. These treatments are susceptible to the surgical technique employed, the design of the autologous block or the tension of the suture. These factors can relate to major complications as the lack of primary closure and dehiscence. The present study, using finite element analysis, aimed to determine differences in terms of displacement of the oral mucosa, transferred stress according to Von Mises and deformation of soft tissue when two block graft designs (right-angled and rounded) and two levels of suture tension (0.05 and 0.2 N) were combined. The results showed that all the variables analyzed were greater with 0.2 N. Regarding the design of the block, no difference was found in the transferred stress and deformation of the soft tissue. However, displacement was related to a tendency to dehiscence (25% greater in the right-angled/chamfer design). In conclusion different biomechanical behavior was observed in the block graft depending on the design and suture tension, so it is recommended to use low suture tension and rounded design. A novel finite element analysis model is presented for future investigations.

Locked Posterior Shoulder Dislocation with Impression Fracture Treated All Arthroscopically With the Use of an Allograft Bone Block a Case Report

Locked posterior shoulder dislocations are uncommon and poses many difficulties in diagnosis. They are often overlooked during initial examination and delayed diagnosis adversely affects healing process. Apart from many open treatment options there are reports of single attempts to treat such cases arthroscopically. We present an original case of a posterior locked dislocation of the shoulder joint with a fracture of the lesser tuberosity followed by reverse Hill-Sachs fracture, treated in a novel fashion all-arthroscopically with the use of allogenic bone graft. According to Constant Shoulder Score that tries to asses functional and subjective performance of the shoulder joint before the operation and after 12 months, we achieved a leap from 11% to 84%. The patient restored almost full range of motion and painless movement in activi-ties of daily life as well as during sports. The use of an arthroscopy reduces the invasiveness of the procedure, improves visualization of the joint and allows augmentation of the bone loss without performing an open approach. We believe that this is A promising method of treatment for selected cases of locked posterior shoulder dislocation.

Influence of Graft Positioning during the Latarjet Procedure on Shoulder Stability and Articular Contact Pressure: Computational Analysis of the Bone Block Effect.

The Latarjet procedure is the most popular surgical procedure to treat anterior glenohumeral (GH) instability in the presence of large anterior glenoid bone defects. Even though the placement of the bone graft has a considerable influence on its efficacy, no clear indications exist for the best graft position. The aim of this study was to investigate the influence of the medial-lateral positioning of the bone graft on the contact mechanics and GH stability due to the bone block effect. Four finite element (FE) models of a GH joint, with a 20% glenoid bone defect, treated by the Latarjet procedure were developed. The FE models differed in the medial-lateral positioning of the bone graft, ranging from a flush position to a 4.5 mm lateral position with respect to the flush position. All graft placement options were evaluated for two separate shoulder positions. Anterior GH instability was simulated by translating the humeral head in the anterior direction, under a permanent compressive force, until the peak translation force was reached. Joint stability was computed as the ratio between the shear and the compressive components of the force. The lateralization of the bone graft increased GH stability due to the bone block effect after a 3 mm lateralization with respect to the flush position. The increase in GH stability was associated with a concerning increase in peak contact pressure due to the incongruous contact between the articulating surfaces. The sensitivity of the contact pressures to the medial-lateral positioning of the bone graft suggests a trade-off between GH stability due to the bone block effect and the risk of osteoarthritis, especially considering that an accurate and consistent placement of the bone graft is difficult in vivo.

Clinical and Radiological Outcomes in Patients With Anterior Shoulder Instability and Glenoid Bone Loss after Arthroscopic Free Bone Block Combined With Dynamic Anterior Stabilization

Background: As an alternative to the Latarjet procedure, the arthroscopic free bone block (FBB) procedure combined with dynamic anterior stabilization (DAS) has been recently proposed to provide both glenoid augmentation and a tendon sling effect for treating anterior shoulder instability (ASI) with glenoid bone loss. Purpose: To evaluate the clinical and radiological outcomes of FBB-DAS for ASI with glenoid bone loss. Study Design: Case series; Level of evidence, 4. Methods: Patients who underwent arthroscopic FBB-DAS for ASI with >15% glenoid bone loss between February 2017 and March 2020 were screened and enrolled in this study. Clinical outcome measures were assessed preoperatively and at a minimum 2-year follow-up, including recurrence, complications, shoulder functional scores, range of motion, and return to sports. Postoperative computed tomography and magnetic resonance imaging were also performed. Results: Of a total of 65 patients with a mean follow-up of 46.1 ± 13.1 months, no patients experienced a recurrent dislocation or subluxation postoperatively, while 2 had a positive anterior apprehension test (3.1%). Additionally, 2 patients (3.1%) experienced complications of hematoma and shoulder stiffness, respectively. The mean visual analog scale score, American Shoulder and Elbow Surgeons score, Rowe score, and Oxford Shoulder Instability Score all improved significantly from 3.2 ± 2.4, 75.0 ± 18.9, 43.6 ± 27.3, and 33.8 ± 9.0 preoperatively to 1.3 ± 0.8, 95.1 ± 8.0, 95.5 ± 7.8, and 14.8 ± 3.5 at final follow-up, respectively (all P < .001). No difference was detected in range of motion except for 8.1° and 7.5° external rotation limitations in adduction and abduction, respectively. There were 62 patients (95.4%) who returned to sports, and 54 patients (83.1%) returned to the preinjury level. The transferred biceps tendon was intact in all 59 patients who completed radiological examination at the latest follow-up. Good bone healing was achieved in 98.3% of patients, and the glenoid bone defect decreased from 18.1% to 4.9%. Osseous and labral glenoids were significantly enlarged in width and depth on the latest magnetic resonance imaging (all P < .001). Conclusion: Arthroscopic FBB-DAS provided satisfactory clinical and radiological outcomes for ASI with glenoid bone loss. Despite slight external rotation restrictions, it achieved low recurrence and complication rates, excellent shoulder functional scores, a high return-to-sports rate, and favorable graft healing and remodeling.

Влияние метода обработки кости на ее прочность

Introduction Bone graft is the best option to repair postsurgical bone defects. The biomaterial is highly adaptive, structurally dynamic, metabolically active and characterized by high strength. Standard preparation of grafts for implantation includes cleaning followed by deep freezing and sterilization. However, methods used for processing bone material and reagents can change the biomechanical properties of the bone. The purpose was to explore the effect of chemical purification and subsequent lyophilization on the mechanical strength of bone grafts in comparison with native fresh frozen bone. Material and methods Metaepiphyseal sections of a single level of one tibia of a single cattle were used to rule out the influence of the variable density of native bone obtained from different donors. The bone was cut into blocks with a hand saw. Three groups of samples formed depending on the processing method included freshly frozen native bone, bone purified by combined chemical and physical methods and bone purified by the same technique followed by lyophilization. Mechanical properties were measured by axial compression mode using a 1958U-10-1 strength machine. Statistical data analysis was performed using the Kolmogorov-Smirnov (K-S) test and the Lilliefors correction with statistical significance of differences assessed with one-way analysis of variance (One-Way ANOVA). Results The cross-sectional area of hand-made blocks was comparable. No decrease in bone strength below the baseline was recorded regardless of the method of bone processing. Purified bone blocks demonstrated maximum strength characteristics prior to lyophilization. The sample strength decreased after lyophilization and was higher as compared to freshly frozen native bone. No statistically significant differences in the maximum force applied and the cross-sectional area were recorded between groups of samples. Modulus of elasticity and relative deformation had statistically significant differences in the groups (p &lt; 0.05). Conclusion Modern methods of bone processing were shown to maintain biomechanical properties of the bone and can be used in the form of bone blocks or chips and as a structural graft.

Bone regeneration for dental implant placement: A 5-year retrospective ​study of 358 cases

Introduction: Bone regeneration techniques are essential prior to dental implant placement in cases of mandibular or maxillary bone deficit. Depending on the area and the extent of bone loss, as well as the type of prosthetic rehabilitation to be applied, different bone regeneration techniques can be used. Aim: The scope of this study is to analyze a series of patients that underwent mandibular or maxillary bone regeneration, in effort to highlight the most widely used techniques and their outcome. Materials and Methods: 358 cases that underwent max- illary or mandibular bone regeneration in an oral and maxillofacial private clinic within the last 5 years are thoroughly analyzed retrospectively in terms of various parameters from their demographic and medical re- cords, the type of bone regeneration technique that was applied and the final bone augmentation and implant osseointegration outcome. Results: The most widely used technique for bone re- generation was GBR (n=184, 51.3%), followed by sinus floor elevation (n=162, 45.3%) and autologous onlay bone block grafts (n=12, 3.4%). In 1 case of GBR with a non-resorbable membrane, membrane exposure was noted. In 5 cases of sinus lift, inflammation occurred. In one case with bone block grafts from the iliac crest, inflammation presented a few weeks after surgery and one of the bone blocks was partially resorbed. Conclusions: GBR with a resorbable membrane barrier and sinus lift appears to have the most predictable outcomes in terms of mandibular or maxillary bone augmentation.

Abstract B017: Dysregulation of ultra long-range DNA methylation canyon interactions in human acute myeloid leukemia

Abstract DNA methylation Canyons (DMCs) are genomic regions devoid of DNA methylation over 3.5kb in hematopoietic stem cells (HSCs). DMCs form ultra long-range interactions spanning decades of megabases specifically in HSCs. These ultra-long DMC interactions between DMCs relies on the strong Polycomb binding inside DMC regions. DMCs are hypermethylated and partially activated in cancer. However, its 3D genomic alterations have not been examined extensively. Here we profiled the high-resolution 3D genomic interactions in 7 primary human acute myeloid leukemia (AMLs). Focusing on DMCs' epigenome state, we found that DMCs in all AMLs are hypermethylated and lose the strong Polycomb enrichment within DMCs in comparison with HSC. Based on the DMC interactions, we discovered two subtypes of AMLs with distinct 3D genomic dysregulation of DMCs’ long-range interactions. In the first AML subtype, DMCs’ interactions are still strong as HSPC but gained leukemia-specific long-range interactions. This subtype is enriched for WT1 mutations and is characterized by the expression of CD34 on blast cells. This particular subtype displayed a global basal level increase in the H3K27me3 mark in the genome. This particular subtype of AML is also sensitive to the EZH2 inhibitor treatment. The EZH2 inhibitor treatment leads to the differentiation of blasts and reduces the colony-forming ability of this subtype of AML. Further dissection shows the EZH2 inhibitors could eradicate the leukemia-specific ultra-long range interactions. In the second subtype of AML, 3D genomic interactions between DMCs significantly lost in AMLs with high HOX cluster gene expression (MLL-r and NPM1c+ AMLs). We further found repressive DMC genes, which are developmental transcriptional factors(TFs) in organ formation are activated in these AMLs. Interestingly, these developmental TFs are involved in forming leukemia-specific long-range interactions independent of CTCF-mediated TADs and chromosomal loops. Among those TFs, IRX3 and IRX5 are frequently activated in MLL-r, NPM1c+ AML and MPAL. These two genes have also been shown before to immortalize bone marrow progenitor cells and block differentiation of these progenitor cells. The loci of these two genes form strong long-range connections to an upstream FTO enhancer mimicking the 3D genomic structure observed in developing muscle and brains. Citation Format: Xue Qing D. Wang, Fan Feng, Yali Dou, Jie Liu, Xiaotian Zhang. Dysregulation of ultra long-range DNA methylation canyon interactions in human acute myeloid leukemia. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Epigenomics; 2022 Oct 6-8; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_2):Abstract nr B017.

Cover Image

AbstractThe cover image is based on the Original Article Fully digital versus conventional workflow for horizontal ridge augmentation with intraoral block bone: A randomized controlled clinical trial by Ning Zhu DMD et al., https://doi.org/10.1111/cid.13129. image

Anterior cruciate ligament reconstruction with all-soft tissue quadriceps tendon versus quadriceps tendon with bone block.

The purpose of this study was to evaluate whether there was a difference in clinical outcomes between patients who underwent primary ACL reconstruction (ACLR) with all-soft tissue quadriceps tendon (sQT) autograft versus QT with bone block (bQT). A retrospective cohort study of 708 patients who underwent QT ACLR was conducted. Primary ACLR patients with at least 1year of follow-up were identified and those who received sQT were compared to those who received bQT. Data collection entailed patient demographics, surgical variables, patient reported outcomes (PROs), knee stability testing, and complications. The primary outcome of interest was International Knee Documentation Committee (IKDC) score, reported as mean score, pre- and postoperative difference, and number who met minimum clinically important difference (MCID). Secondary outcomes included Lachman and pivot shift grade, other patient reported outcomes (PROs), complication rates, and return to sport (RTS). A total of 195 patients (147 sQT, 48 bQT) who underwent primary QT ACLR met criteria for analysis, with mean follow-up of 17.0 ± 7.9months. No difference was detected between cohorts with respect to postoperative IKDC score (sQT: n = 120, 81.0 ± 18.9, bQT: n = 10, 80.9 ± 20.4, n.s.), proportion of patients who met MCID (sQT: 68/78 [87%], bQT: 6/7 [86%], n.s.), or results of stability testing. In the sQT cohort, 86% (106/123) of athletes achieved full RTS, compared to 85% (34/40) in the bQT cohort (n.s.). Time to RTS was less than a year in both cohorts (sQT: 10.5 ± 3.8months [n = 106], bQT: 11.1 ± 3.9months [n = 31], n.s.). Graft rupture occurred in 7 (5%) sQT patients and 3 (6%) bQT patients (n.s.), and all clinical failures were due to graft rupture (n.s.). No differences were detected for rates of postoperative complications. No differences in clinical outcomes were detected between patients who underwent primary ACLR with sQT autograft versus bQT autograft. Currently, the decision to employ sQT or bQT is largely determined by surgeon preference. This study demonstrates excellent outcomes with both preparations and supports the use of either graft type at the discretion of the treating surgeon. III.

A method for determining the optimal technique of surgical intervention in patients with post-traumatic kyphotic deformity of the thoracolumbar spine in the late period of spinal injury.

Introduction. Spinal fractures account for 63.6 cases per 100,000 populations. Of these, the largest number falls on the Th10-L2 zone. Regardless of the choice of treatment tactics in the early period of spinal injury, a vast number of patients continue to complain of local pain and deformity. In these patients, surgical treatment may be indicated. At the preoperative stage, the operating surgeon faces the problem of choosing an intervention of sufficient volume.The aim of the study was to determine the optimal amount of corrective surgical interventions in patients with kyphotic deformity that has developed as a result of a vertebral fracture.Methods. Patients with a medical history of vertebral compression fracture and local kyphotic deformity greater than 11 degrees were enrolled in a single-centre, prospective, experimental study. All patients were divided into three groups according to the studied algorithm. Patients in group A underwent two-stage surgical treatment with corporectomy, implantation of a mesh interbody implant, and posterior transpedicular fixation from two approaches. Group B patients underwent one-stage surgical treatment with corporectomy and implantation of a mesh interbody implant from a single approach. Patients of group C underwent corrective vertebrotomy without the use of a mesh implant. The degree of deformity correction, the traumatism of surgical intervention, the stability of the metal structure, the formation of a bone block, and changes in the functional status of the patient were assessed. Patients were followed up for 24 months after surgical treatment.Results. The study was completed by 114 patients. Surgical treatment options used allowed achieving good results in the correction of deformity in all groups, in groups B and C the traumatism of the operation was significantly (p=0.05) lower than in group A. A bone block was formed in all study groups. It is important to note that patients in group B had transient radicular pain in the early postoperative period, which probably associated with the traction of neural structures during the installation of an interbody mesh implant.Conclusion. Application of the presented algorithm allowed us to achieve comparable beneficial results in patients of all study groups, however, a small sample and the absence of control subgroups do not allow us to extrapolate the study results to the entire population.

Anterior Dental Implant in Grafted Cleft Alveolus: A Clinical Comparison Between Intramembranous and Endochondral Bone Graft.

Alveolar bone graft is usually performed during the early mixed dentition phase, at the chronological age of 6 to 8 years old, to reconstruct the cleft alveolus. As the appropriate time for implant placement is after completion of full growth, it can result in a likelihood of resorption. The aim of this study is to compare the clinical outcomes of anterior dental implants with delayed bone grafting using iliac crest (endochondral) and mandibular ramus or symphysis (intramembranous) bone in adolescents to adulthood patients with cleft alveolus. This study included 10 patients with cleft alveolus who underwent delayed bone grafting with autogenous block bone and particulate cancellous bone and marrow (PCBM) from the mandibular ramus and symphysis with dental implant placement, and iliac crest. The success of the treatment was evaluated through clinical and radiographic examination including marginal bone loss measurement of the implants. All patients underwent delayed bone grafting between the ages of 11 and 21.1 years (mean age: 15.1±4.3y). The implant diameters ranged from 3.8 to 4.5mm and the lengths ranged from 8.0 to 11.5mm. All of the implants were integrated successfully and survived during the 3-year follow-up period. Delayed bone grafting followed by implant placement showed long-term stability with satisfactory esthetic and functional rehabilitation. One of the main advantages of delayed bone grafting is to achieve adequate bone support for future dental implant placements with less bone resorption compared with those of primary, early secondary, and secondary bone grafting.

Latarjet coracoid transfer vs. distal clavicle autograft for anterior shoulder instability with glenoid bone loss: A biomechanical comparison of two graft reconstructions in various medial to lateral positions

While the consensus of optimal positioning of the transferred coracoid, no biomechanical study has established if the position differs for other bone block types. To compare the effect of distal clavicle autograft and coracoid autograft alignment and medialization on glenohumeral stability. Eight Fresh-frozen cadaver shoulders comprised of the scapula and proximal humerus were tested. The cadavers were tested while positioning both grafts, the distal clavicle autograft and coracoid graft, consecutively at 0 mm, 4 mm and 8 mm medially. Each experiment comprised of maximum external rotation and glenohumeral abduction of 60° while applying a constant, 50 N medial compressive force via a pneumatic actuator to the humerus under all conditions. The starting position was determined by the humeral head being seated at its most medial position on the glenoid surface. The conjoint tendon was routed through a split in subscapularis and loaded with a 5N weight using a pulley system for all Latarjet trials to simulate the sling effect. Clavicle grafts at all offsets showed a statistically significant decrease in the stability ratio versus the intact condition. Within the clavicle graft conditions, the 4 mm clavicle offset had a significantly lower stability ratio versus the 0 mm clavicle offset and a significantly higher stability ratio than the 8 mm offset. The clavicle 8 mm offset graft had a significantly lower stability ratio than the 0 mm offset position. The Latarjet graft with 0 mm of medial offset showed no statistically significant difference in stability ratio when normalized at 10 mm of anterior displacement relative to the intact glenoid condition, while the 4 mm and 8 mm medial offset Latarjet conditions had significantly lower stability ratios versus the intact condition. Within the Latarjet graft positions, the stability ratio of the 4 mm medial offset had no statistically significant difference than the 0 mm offset. In shoulders with anterior glenoid bone loss, the Latarjet procedure and transfer of an osteoarticular distal clavicle autograft seem to be biomechanically sound if placed flush with the glenoid. Medialization of 4 mm provides acceptable restoration of shoulder stability when a Latarjet procedure is used but not for a distal clavicle autograft.

Soft-tissue dimensional change following guided bone regeneration on peri-implant defects using soft-type block or particulate bone substitutes: 1-year outcomes of a randomized controlled clinical trial.

To compare the peri-implant soft-tissue dimensional changes following guided bone regeneration between particulate (particle group) and collagenated soft-block-type (block group) biphasic calcium phosphate (BCP). This study investigated 35 subjects: 18 in the particle group and 17 in the block group. Cone-beam computed tomography obtained at 6months post surgery and optical impressions taken periodically (before surgery, 6months post surgery, and 1year post surgery) were superimposed. The ridge contour changes over time and the peri-implant mucosal thicknesses were measured diagonally and horizontally, and analysed statistically. The increases in diagonal (1.12 ± 0.78 mm) and horizontal (2.79 ± 1.90 mm) ridge contour of the block group were significantly higher than those in the particle group during the first 6months (p< .05); however, the contour hardly changed thereafter (diagonal: 0.07 ± 0.75 mm; horizontal: -0.34 ± 1.26 mm), resulting in the 1-year contour changes similar between the two groups. Regardless of the type of BCP, the ridge contour increased significantly over 1year when the dehiscence defect had a contained configuration (p< .05). The increase in soft-tissue dimensions for 1year was similar between the two groups. The mucosal contour increase was larger when the surgery was conducted in a more contained defect, and this was not influenced by the type of BCP.

Technique of ACL Reconstruction With Autologous Quadriceps Tendon Bone Graft and Femoral Press Fit Fixation

Background: Recently, there has been an increase in interest in the quadriceps tendon (QT) as an alternative autologous graft option for primary anterior cruciate ligament (ACL) reconstruction. Indication: Anterior cruciate ligament reconstruction in skeletally mature patients (high-risk patients for re-rupture and patients with medial instability). Technique Description: The QT graft is harvested with a 4-cm skin incision over the superior pole of the patella. A double knife and an oscillating saw are used to obtain the QT graft with a bone block from the patella (65 mm x 10 mm graft and 15 mm bone block). Then an arthroscopy is carried out with assessment of the ACL tear and treatment of further intraarticular injuries. ACL reconstruction begins with debridement of the femoral insertion to expose the land marks. The medial portal is used for femoral tunnel drilling with the knee in more than 110° of flexion. A special portal aiming device is introduced via the anteromedial portal and a guide wire is placed in the area of the femoral anteromedial insertion. This guide wire is gradually overdrilled with various drills and dilators of increasing size. The final diameter should be 0.5 mm smaller than the diameter of the bone block of the graft to allow for press-fit fixation. Then, the tibial tunnel is drilled using a tibial drill guide leaving the tibial stump of the original ACL intact. The graft is pulled into the joint through the tibial tunnel until the bone block stops at the femoral tunnel entrance. The bone block is then pushed through the medial portal into the femoral tunnel (press-fit fixation). The tibial fixation is performed with an interference screw and optionally with an extracortical button. Results: Prior studies with 2 years follow-up have shown that the clinical outcomes in primary and revision ACL reconstruction were not significantly different between the use of QT grafts with femoral press-fit fixation and the use of hamstring grafts with femoral suspension fixation. Discussion/Conclusion: Quadriceps tendon bone autograft and femoral press-fit fixation provides an excellent alternative as a graft choice in ACL reconstruction. The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Tuberosity reconstruction baseplate for shoulder hemiarthroplasty: Morphological design and biomaterial application.

Background: Shoulder hemiarthroplasty is prone to tuberosity malposition and migration, reducing the rate of tuberosity healing. We proposed to design a tuberosity reconstruction baseplate to assist in tuberosity integration and to evaluate the mechanical properties of baseplate made from the novel biomaterial carbon fiber reinforced polymer (CFRP) composites. Methods: The three-dimensional model of native proximal humerus was constructed by computed tomography (CT) data. The morphological design of baseplate was based on the tuberosity contour and rotator cuff footprint. Finite element models were created for different thicknesses of CFRP composites, poly (ether-ether-ketone) (PEEK) and titanium-nickel (TiNi) alloy. The permissible load and suture hole displacements were applied to evaluate the mechanical properties. Results: The structurally optimized model made of CFRP composites provided superior strength and deformability, compared to the PEEK material and TiNi alloy. Its permissible load was above 200N and the suture hole displacement was between 0.9 and 1.4mm. Conclusion: This study proposed a method for designing tuberosity reconstruction baseplate based on morphological data and extended the application of biomaterial CFRP composites in orthopedics field. The optimized model made of CFRP composites allowed a certain extent of elastic deformation and showed the possibility for dynamic compression of tuberosity bone blocks.

Osteogenic Differentiation of Periodontal Ligament Stem Cells Seeded on Equine-Derived Xenograft in Osteogenic Growth Media.

Background and Objectives: The duration of bone turnover is critical, and different time points help in identifying the optimal endpoint of treatment duration. However, investigating the combination of xenograft and stem cells to allow tissue regeneration within an ideal time duration remains an under-investigated topic. The current study aimed to assess the impact of equine-derived xenograft bone blocks in assisting the human periodontal ligament stem cells (PDLSCs) to demonstrate osteogenic differentiation (collagen type 1 expression and calcium deposition) within an osteogenic growth media. Materials and Methods: Human PDLSCs were acquired commercially and seeded onto xenograft bone blocks. After the 14th and 21st day of culture, enzyme-linked immunoassay (ELISA) was utilized for the detection and quantification of levels of collagen type I, while the mineralization assessment (deposition of calcium) was conducted by staining the PDLSCs with Alizarin Red S (ARS). The statistical comparison between the means and standard deviations of study groups were evaluated using analysis of variance (ANOVA). Results: ELISA assessment revealed an upsurge in the expression of collagen type I for PDLSCs cultured with xenograft after 14 and 21 days compared to the controls (intergroup comparisons significant at p &lt; 0.05). Similar findings were obtained for mineralization assessment and on ARS staining. PDLSCs cultured with xenograft bone blocks presented an increased deposition of calcium compared to their control counterparts (intergroup comparisons significant at p &lt; 0.05). Conclusions: PDLSCs embedded in xenograft bone blocks inside an osteogenic growth medium demonstrated greater osteogenic differentiation potential after 14 and 21 days. This superior osteogenic differentiation capability was evident by increased collagen type I expression and more significant calcium deposition at the 14th and 21st days after culture.

Biomechanical Comparison and Three-Dimensional Analysis of Cement Distribution Patterns for Different Pedicle Screw Designs.

The purpose of this study to explore strategies for reducing cement leakage during cement-augmented pedicle screw fixation, we compared the cement distribution patterns and biomechanical strengths of different types of cement-augmented fenestrated screws and traditional cement-augmented techniques. We compared five screw groups in this study: (1) Cannulated screws (Cann); (2) distal one-hole screws (D1); (3) distal two-hole screws (D2); (4) middle two-hole screws (M2); and (5) traditional screws with a traditional cement injection technique (Trad). The screws were inserted into cancellous bone blocks using a controlled, adequate cement injection pressure (1.6–2.0 kg), and an appropriate cement viscosity. Center to screw tip distance, three-dimensional distribution, and pull-out strength for cement were compared between groups. The average distance between the cement center and the screw tip was highest in the M2 group, suggesting a higher risk of cement leakage into the spinal canal. The Trad group had the highest migration distance in the z-axis, also reflecting a higher risk of leakage into the spinal canal. The D1 group had the highest pull-out strength (253 ± 48.82 N and 797 ± 58.31 N) in bone blocks representing different degrees of osteoporosis, and the D2 group had the second highest pull-out strength in the severe osteoporosis model. Overall, D1 screws appeared to be the best option for optimizing biomechanical function and minimizing the risk of cement leakage into the spinal canal in patients with osteoporotic bone undergoing spinal surgery.

Study of Locking Compression Plate Through Biodegradable Implant

Orthopaedic implant biomechanics research is booming, especially in bone fixation. Fixation involves securing a plate to a broken bone. The femur fractured mostly. Long bone fractures can be difficult to cure despite technological and medical breakthroughs. This study analyses the performance and optimal screw arrangement for biodegradable locking compression plate. This study compares biodegradable bone plate materials to identify the best (Iron, Zinc and Magnesium). SolidWorks models fracture repair plates and fixes them in a normal walking condition to a mid-ship fracture. Further, finite element analysis was performed on models with homogeneous and isotropic bone and plate. Simulation was done using COMSOL programme and screws. Idealized poroelastic 3D FE femoral model with 5 mm fracture gap and plate-screw design. We saw stress and displacement. The minimal von Mises stress and deformation for 6 screws. Under pure zinc and magnesium load, the highest von Mises stress was 7.94 MPa and the maximum deformation was 0.08 mm, proving that iron was the best material. Based on finite element analysis, the LCP can offer mechanical stability for comminuted fractures, fixing the bone block and promoting bone healing.

Insertion and removal torque of dental implants placed using different drilling protocols: An experimental study on artificial bone substitutes.

The aim of this in vitro study was to measure the insertion and removal torque values of dental implant replicas inserted into artificial bone blocks using different surgical burs and drilling protocols. Four types of artificial, polyurethane bone blocks were used with different thicknesses (1 and 2mm) and densities (soft-1 mm, soft-2 mm, dense-1 mm, and dense-2 mm) of the simulated cortical and cancellous bone, respectively. Each bone construct was drilled with Straumann and Densah drills in both clockwise and counterclockwise directions for a total of 16 experimental conditions. For every scenario, 38 implant replicas were inserted and then removed after 1 min. Outcomes of interest were the insertion and removal torque values which were recorded by a torque meter. ANOVA and Tukey HSD tests were used to assess differences across each combination of drill, direction, and bone type. Densah counterclockwise registered statistically greater values for both insertion and removal torque, followed by Densah clockwise, Straumann counterclockwise, and Straumann clockwise. Increasing insertion and removal torque values were progressively reported for bone type (soft-1mm, dense-1mm, soft-2mm, and dense-2mm). The mean values of insertion and removal torque were significantly different (p < 0.05) across the four bone types, different burs, and with the two drilling modalities. Densah bur resulted in significantly greater values of torque compared to the Straumann drills for all the experimental conditions. The thickness of the cortical layer and the counterclockwise drilling direction play a significant role in determining the implant insertion torque.

Hemihamate Arthroplasty Revisited: A Retrospective Review of 11 Cases.

Proximal interphalangeal joint (PIPJ) fracture dislocations are complex injuries that can result in persistent pain, stiffness, and angulation. Hemihamate arthroplasty (HHA) can be used to reconstruct the base of the middle phalanx in cases of unstable PIPJ fracture dislocations. Despite previous case series describing good outcomes with HHA, it has not gained widespread use. The purpose of this study is to describe our straightforward, reproducible technique and to demonstrate the benefit in motion after the procedure in chronic unstable PIPJ fracture dislocations. All patients with chronic, unstable PIPJ fracture dislocations requiring joint resurfacing of greater than 40% of the base of the middle phalanx treated with HHA were retrospectively reviewed. Patient demographics, injury features, surgical technique, preoperative and postoperative PIPJ range of motion and arc of motion, time to surgery, and complications were reviewed. Any fracture amenable to fixation or cases with radiographic evidence of arthritis or injury to the head of the proximal phalanx were excluded. Eleven cases were reviewed. The mean patient age was 35 years. The mean time from injury to surgery was 6 months. The mean joint surface involved was 64%. The mean PIPJ arc of motion was 17 degrees preoperatively and 63 degrees postoperatively. The mean bone block size required was 8 × 8 × 8 mm. The mean follow-up was 26 months. Postoperative pain at the PIPJ on the visual analog scale was 0.4 (scale of 0 to 10). Complications included 2 patients requiring tenolysis. Despite the lack of a perfect geometric recreation of the base of the middle phalanx with the hamate, patients recover acceptable PIPJ motion and have minimal pain. Hemihamate arthroplasty is a good option for any patient with minimal motion of their PIPJ and a chronic, unstable fracture dislocation.