Distal Bone Segment Research Articles

Duplex Fluorinated and Atomic Layer Deposition-Derived ZrO2 Coatings Improve the Corrosion Resistance and Mechanical Properties of Mg-2Zn-0.46Y-0.5Nd (wt.%) Alloy Plates and Screws.

This study investigated the corrosion resistance and mechanical properties of Mg-2Zn-0.46Y-0.5Nd (wt.%) alloy plates and screws with fluorinated coatings and atomic layer deposition (ALD)-derived zirconia (ZrO2) coatings in vitro under physiological stress conditions. Synthetic polyurethane hemimandible replicas were split and fixed as the following three groups of magnesium alloy plates and screws: no additional surface coating treatment (Group A), with fluorinated coatings (Group B), and with duplex fluorinated and ALD-derived 100 nm ZrO2 coatings (Group C). A circulating stress of 1-10 N was applied to the distal bone segment, and a 4-week simulated body fluid immersion test was employed to study the remaining material volume and the mechanical properties of the different groups. Compared with Group A and Group B, the degradation rate of magnesium alloy plates and screws' head regions was significantly slowed down under the protection of duplex MgF2/ZrO2 coatings (p < 0.01). There was no significant difference in the degradation rate of the screw shaft region between groups (p = 0.077). In contrast to fluoride coatings, duplex MgF2/ZrO2 coatings maintained the mechanical strength of magnesium alloy plates and screws after a 14 day in vitro SBF immersion test. We conclude that duplex MgF2/ZrO2 coatings exhibited a certain protective effect on the Mg alloy plates and screws under physiological stress conditions.

Accuracy of correction of a hexapod frame, patient-specific osteotomy and reduction guides, and hinged circular external fixation in a 3D-printed canine antebrachial deformity model.

This study aimed to objectively define whether human hexapod fixation (Maxframe), with or without the use of 3D-printed positioning guides, can correct a canine antebrachial deformity with greater accuracy than the clinically established techniques of 3D patient-specific osteotomy and reduction guides (3D-PSORG) or hinged circular external skeletal fixation (CESF). CT of a canine antebrachium was manipulated to induce distal radial deformity of the valgus, external torsion, and procurvatum, each of magnitude 20o. Five experiments were performed to correct the deformity via a distal radial and ulna opening osteotomy using: (1) A 3D-PSORG with the application of a locking plate, (2) hinged CESF, (3) Maxframe standard protocol, (4) Maxframe applied with patient-specific positioning guides (PSPGs), and (5) Maxframe with frame adjustment calculated from post-application CT. Following correction, all constructs were optically scanned, and objective measurement of the correction achieved was performed. No construct returned the distal bone segment to its preoperative position in all planes. Translational malalignment in the sagittal plane had the highest magnitude of error for all constructs, with the Maxframe standard protocol showing the greatest error. Maxframe (PSPGs) showed the minimum error of all constructs in the frontal and sagittal planes. In this 3D-printed model of antebrachial deformity correction, the hexapod frame with the use of PSPGs achieved better accuracy than 3D-PSORG and hinged CESF and may be a technique of future interest and development in the management of canine antebrachial limb deformity.

Mechanical Stability Analysis of the External Unilateral Fixation Device due to the Impact of Axial Pressure

This study performed a mechanical stability analysis for the impact of axial pressure on an Ultra X external unilateral fixation device applied to a tibia with an open fracture. The real construction of the fixation device was used to create a 3D geometric model using a Finite Element Method (FEM) model, which was made to perform structural analysis in the CATIA V5 (Computer Aided Three-dimensional Interactive Application) CAD/CAE system. Specific stresses and displacements were observed at points of interest using structural analysis. The focus was on the relative displacements of the proximal and distal bone segments in the fracture zone. These displacements were used to calculate the stiffnesses of the bone in the fracture zone and the fixation device itself. The results obtained provide the necessary information regarding the stability of the Ultra X fixation device.

Three-dimensional femur morphology analysis for the optimal location of subtrochanteric osteotomy with an implanted Wagner cone stem in total hip arthroplasty for Crowe type IV developmental dysplasia of the hip

BackgroundThis study aimed to accurately evaluate the matching of proximal and distal femoral segments and fitting of the femur–femoral stem in patients with Crowe type IV developmental dysplasia of the hip (DDH) who have undergone subtrochanteric osteotomy at different locations with an implanted Wagner cone stem to improve the rate of the bone union at the osteotomy site.MethodsThree-dimensional femur morphology of 40 patients with Crowe type IV DDH was evaluated at each cross-section to determine the femoral cortical bone area. This study focused on five osteotomy lengths (2.5, 3, 3.5, 4, and 4.5 cm). The overlapped area between the proximal and distal cortical bone segments was defined as the contact area (S, mm2), and the contact area to distal cortical bone area ratio was defined as the coincidence rate (R). Three indicators were used to evaluate the matching and fitting of the osteotomy sites with the implanted Wagner cone stems: (1) higher S and R between the proximal and distal segments; (2) the effective fixation length of the femoral stem at the distal segments being at least 1.5 cm; and (3) osteotomy did not involve the isthmus.ResultsIn all groups, S significantly decreased in the two proximal levels above the 0.5 cm level below the lesser trochanter (LT) compared with those below this level. In comparison, at osteotomy lengths from 2.5 to 4 cm, R significantly decreased in the three proximal levels. The optimal osteotomy levels ranged from 1.5 and 2.5 cm below the LT for an appropriately sized stem.ConclusionsSubtrochanteric osteotomy at the optimal level not only ensures fitting of the femur–femoral stem but also meets the requirements of a higher S and R to ensure adequate reduction and stabilization at the osteotomy site, which may contribute to the bone union. Although the optimal osteotomy level varies with the size of the femoral stem and the length of the subtrochanteric osteotomy, the optimal osteotomy levels for an appropriately sized Wagner cone femoral stem implantation range from 1.5 to 2.5 cm below the LT.

A Novel K-Wiring Technique for the Intraoperative Temporary Stabilisation of Comminuted Fibula Fractures, in Osteopaenic Bone

Introduction: Experience has shown that comminuted fibula fractures in the setting of osteopaenic bone, pose a challenge in operative management. Fractures in the distal-third diaphyseal segment of the fibula, characterised as Weber C fibula fractures are often times highly comminuted, multi-fragmentary fractures. In this situation, the application of the sentinel principal in diaphyseal fracture management, which is to restore length, alignment, and rotation. K-wires are a useful adjunct to temporary fracture reduction/stabilisation. The study presents a novel useful technique which allows maintenance of fracture/bone length, in preparation for the application of a plate to the fibula in a bridging construct. Technique: The fibula fracture is exposed and the fracture defined. Once the overall alignment of the bone is restored, a single ended 2mm k-wire is advanced through the fibula, remote from the fracture and across the interosseous space, and then into the tibia in the trans-fibula plane, stabilising the proximal fibula bone segment, to the tibia. A second wire is then mounted on a driver, and is in turn advanced through the fibula and across into the tibia, in the trans-fibula plane, this time in the distal bone segment, and again remote from the fracture. The wires are individually advanced through the tibia until such time as they protrude from the medial tibial surface a sufficient length that the wire might be then gripped with the wire driver on the medial side of the limb. The wires are pulled from the medial side, until the wire tip lies flush with the cortical bone surface, just visible to the naked eye, such that if a plate were applied it could be seated, unimpeded by the wire. Discussion: The trans-fibula plane has been proven to be a safe plane upon which to advance a wire from the fibula, and through the tibia.

In vitro analysis and in vivo assessment of fracture complications associated with use of locking plate constructs for stabilization of caprine tibial segmental defects

PurposeLocking plate fixation of caprine tibial segmental defects is widely utilized for translational modeling of human osteopathology, and it is a useful research model in tissue engineering and orthopedic biomaterials research due to its inherent stability while maintaining unobstructed visualization of the gap defect and associated healing. However, research regarding surgical technique and long-term complications associated with this fixation method are lacking. The goal of this study was to assess the effects of surgeon-selected factors including locking plate length, plate positioning, and relative extent of tibial coverage on fixation failure, in the form of postoperative fracture.MethodsIn vitro, the effect of plate length was evaluated using single cycle compressive load to failure mechanical testing of locking plate fixations of caprine tibial gap defects. In vivo, effects of plate length, positioning, and relative tibial coverage were evaluated using data from a population of goats enrolled in ongoing orthopedic research which utilized locking plate fixation of 2 cm tibial diaphyseal segmental defects to evaluate bone healing over 3, 6, 9, and 12 months.ResultsIn vitro, no significant differences in maximum compressive load or total strain were noted between fixations using 14 cm locking plates and 18 cm locking plates. In vivo, both plate length and tibial coverage ratio were significantly associated with postoperative fixation failure. The incidence of any cortical fracture in goats stabilized with a 14 cm plate was 57%, as compared with 3% in goats stabilized with an 18 cm plate. Craniocaudal and mediolateral angular positioning variables were not significantly associated with fixation failure. Decreasing distance between the gap defect and the proximal screw of the distal bone segment was associated with increased incidence of fracture, suggesting an effect on proximodistal positioning on overall fixation stability.ConclusionsThis study emphasizes the differences between in vitro modeling and in vivo application of surgical fixation methods, and, based on the in vivo results, maximization of plate-to-tibia coverage is recommended when using locking plate fixation of the goat tibial segmental defect as a model in orthopedic research.

Biomechanical evaluation of the proximal chevron osteotomy in comparison to the Lapidus arthrodesis for the correction of hallux valgus deformities

PurposeThe proximal chevron osteotomy and the modified Lapidus arthrodesis are both procedures utilized for deformity correction in patients with severe symptomatic hallux valgus. The aim of the current study was to compare their biomechanical stability when using locking plate fixation.MethodsTwelve matched pairs of human anatomical lower leg specimens underwent on one side a proximal chevron osteotomy with a medial locking plate and on the other side a modified Lapidus arthrodesis with a plantar locking plate utilizing an interfragmentary compression screw. All specimens underwent bone mineral density (BMD) assessment and were tested in a servohydraulic load frame which applied a load on the centre of the metatarsal head over 1000 loading cycles with subsequently ultimate load testing. Displacement of the proximal and distal bone segment, ultimate load, and bending stiffness were analyzed.ResultsMean displacement of both procedures showed no statistically significant difference throughout all the loading cycles (0.213 ≤ p ≤ 0.834). The mean ultimate load of the proximal chevron osteotomy was 227.9 N (± 232.4) and of the modified Lapidus arthrodesis 162.9 N (± 74.6) (p = 0.754). The proximal chevron osteotomy (38.2 N/mm (± 24.9)) had a significantly higher bending stiffness compared to the modified Lapidus arthrodesis (17.3 N/mm (± 9.9)) (p = 0.009). There was no correlation between BMD and displacement in all loading cycles, ultimate load, and bending stiffness of either procedure (p > 0.05).ConclusionAlthough the bending stiffness of the chevron osteotomy was higher, there was no statistically significant difference between the surgical techniques in mean displacement and ultimate load. The BMD did not influence the overall stability of either reconstruction. Locking plate fixation increases the clinical value of the modified Lapidus arthrodesis by outweighing most of the biomechanical disadvantages in comparison to the proximal chevron osteotomy.

Orthognathic surgery in the mandibular advance: a systematic review

Introduction: Orthognathic surgery is a standardized procedure used to improve a patient's facial appearance and to correct maxillary and mandibular deformities resulting from malocclusions, disease or trauma. Bilateral sagittal osteotomy of the mandibular ramus is a technique widely used in orthognathic surgery to correct mandibular deformities. Mandibular advancement is a procedure with a high risk of skeletal recurrence, due to the difference between the proximal and distal bone segments. Objective: To carry out a systematic review of orthognathic surgery in the mandibular advance, focusing on the main challenges and importance. Methods: The present study was followed by a systematic literature review model - PRISMA rules. The quality of the studies was based on the GRADE instrument. The risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: Bilateral sagittal osteotomy is the most used technique in mandibular orthognathic surgery, allowing mandibular movements in the sagittal, vertical and transverse directions, with good results and few complications. However, this technique can cause mandibular advancements above 10 mm, strongly pointing to the placement of a bone graft in order to avoid defects and their complications. Therefore, in orthognathic surgery, bone grafting can accelerate bone formation.

A Linkage Representation of the Human Hand Skeletal System Using CT Hand Scan Images

The present study proposed a method for establishing a linkage representation of the human hand skeletal system. Hand skeletons of 15 male subjects were reconstructed from computed tomography (CT) scans in 10 different postures selected from a natural hand-closing motion. The wrist joint center was estimated as the intersection of the centerline of the metacarpal of the middle finger and the distal wrist crease. The remaining joint centers were kinematically estimated based on the relative motion between the distal bone segment and the proximal bone segment of a given joint. A hand linkage representation was then formed by connecting the derived joint centers. Regression models for predicting internal hand link lengths using hand length as the independent variable were established. In addition, regression models for predicting the joint center coordinates of the thumb carpometacarpal (CMC) and finger metacarpophalangeal (MCP) joints using hand length or hand breadth were established. Our models showed higher R2 values and lower maximum standard errors than the existing models. The findings of the present study can be applied to hand models for ergonomic design and biomechanical modeling.

The role of remnant bone microbiological cultures in managing diabetic foot osteomyelitis

Aim: Effective treatment of diabetic foot osteomyelitis can reduce the risk of major amputations. Our primary aim was to compare the yield in cultures from the proximal and distal segments of bone excised intraoperatively and the impact on antibiotic choice and duration.Methods: Patients with a confirmed diagnosis of osteomyelitis on bone culture results, where both proximal and distal bone segment samples had been collected, were retrospectively reviewed. Microbiological data were examined to identify true pathogens and studied against antimicrobial choice and duration of prescribing.Results: A total of 47 forefoot amputation cases were studied. In 89% of cases, definite or likely pathogens were isolated from the deep tissues cultured. Definite pathogens (Staphylococcus aureus, Group B streptococcus, Group G streptococcus and Streptococcus anginosus) were identified in 32% of cases; in 73% of these, definite pathogens were grown in both the proximal and distal bone segments.Conclusion: Sampling of remnant bone culture can help in reducing the duration of antibiotic treatment in patients (27% of cases in our series) as it is challenging to correctly estimate intraoperatively whether clear surgical margins have been adequately achieved when resecting infected bone.

Estimation of Finite Finger Joint Centers of Rotation Using 3D Hand Skeleton Motions Reconstructed from CT Scans

The present study proposed a method to estimate the finite finger joint centers of rotation (CoRs) with high accuracy using 3D hand skeleton motions reconstructed from CT scans. Ten hand postures starting from a fully extended posture and ending at a fist posture with about 10° difference in flexion between the adjacent postures were captured by a CT scanner for 15 male participants, and their 3D hand skeletons were reconstructed using the CT scans. Each bone segment from the full extension posture was registered to the corresponding bone segments of the remaining hand postures. The proximal bone segments of a joint from two postures were aligned to estimate the finite CoR of the joint between the two postures. Centerlines of the distal bone segments of the joint were then identified using the principal component analysis method, and the finite CoR of the joint was determined as the intersection point of the identified centerlines. The proposed method reduced the variation of estimated finite joint CoRs by 16.0% to 67.0% among the finger joints compared to the existing methods. The variation of estimated finite joint CoRs decreased as the rotation angle of the joint increased. The proposed method can be used for the simulation of finger movement with high accuracy.

Variable fixation promotes callus formation: an experimental study on transverse tibial osteotomies stabilized with locking plates

BackgroundA new locking screw technology, named variable fixation, has been developed aiming at promoting bone callus formation providing initial rigid fixation followed by progressive fracture gap dynamisation. In this study, we compared bone callus formation in osteotomies stabilized with standard locking fixation against that of osteotomies stabilized with variable fixation in an established tibia ovine model.MethodsA 3 mm tibial transverse osteotomy gap was stabilized in three groups of six female sheep each with a locking plate and either 1) standard fixation in both segments (group LS) or 2) variable fixation in the proximal and standard fixation in the distal bone segment (group VFLS3) or 3) variable fixation in both segments (group VFLS6). The implantation site and fracture healing were compared between groups by means of radiologic, micro tomographic, biomechanical, and histological investigations.ResultsCompared to LS callus, VFLS3 callus was 40% larger and about 3% denser, while VFLS6 callus was 93% larger and its density about 7.2% lower. VFLS3 showed 65% and VFLS6 163% larger amount of callus at the cis-cortex. There wasn’t a significant difference in the amount of callus at the cis and trans-cortex in groups featuring variable fixation only. Investigated biomechanical variables were not significantly different among groups and histology showed comparable good healing in all groups. Tissues adjacent to the implants did not show any alteration of the normal structure in all groups.ConclusionsVariable fixation promoted the formation of a larger amount of bone callus, equally distributed at the cis and trans cortices. The histological and biomechanical properties of the variable fixation callus were equivalent to those of the standard fixation callus. The magnitude of variable fixation had a biological effect on the formation of bone callus. At the implantation site, the usage of variable fixation did not raise additional concerns with respect to standard fixation. The formation of a larger amount of mature callus suggests that fractures treated with variable fixation might have a higher probability to bridge the fracture gap. The conditions where its usage can be most beneficial for patients needs to be clinically defined.

Effect of cyclic loading on the stability of screws placed in the locking plates used to bridge segmental bone defects.

The objective of this study was to evaluate the ex vivo effect of cyclic loading on the stability of screws placed in locking plates used to bridge segmental bone defects. The primary interface stability was assessed using peak reverse torque. Eighteen, 8‐hole stainless‐steel 4.5 mm locking plates and 4.0‐mm self‐tapping locking‐head screws were used to stabilize 40‐mm segmental defects in goat tibiae. Treatment groups included control constructs without cyclic loading (n = 6) and constructs tested to 5000 (n = 6) and 10,000 cycles (n = 6) of 600 N compressive axial loading. The insertion of all screws was standardized to 400 N‐cm insertion torque. Peak reverse torque was measured immediately after screw placement (control), or after the completion of the respective loading cycles. The difference between treatment groups was compared using univariate analysis of variance. The analysis revealed a significant difference in peak reverse torque of the screws among the treatment groups (p = .000). The mean reverse torque values equaled 343.5 ± 18.3 N‐cm for non‐cycled controls, 303.3 ± 25.9 and 296.0 ± 42.9 N‐cm after 5000 and 10,000 cycles, respectively. Among all treatment groups, screws placed in the distal bone segment tended to have lesser peak reverse torque reduction than those placed in the proximal segment and the difference was proportional to the number of cycles (p = .562; p = .255; p = .013 in control, and after 5000 and 10,000 cycles, respectively). Cyclic loading may have a negative effect on the primary stability of screws placed in locking plate constructs used to bridge segmental bone defects and could contribute to the risk of screw loosening.

Primary Leiomyosarcoma of Humerus Presenting with Pathological Fracture and Treated Initially with Inadvertent Plate Fixation: a Case Report with Literature Review

Leiomyosarcoma is a malignant tumor of smooth muscle origin and commonly diagnosed in the uterus, gastrointestinal tract, and mucous membranes or as metastasis to the skeletal system. Primary leiomyosarcoma of bone is an uncommon type of tumor. Patient with primary bone sarcoma may present with a pathological fracture following a trivial injury, resulting in pain, swelling, and deformity. The pathological fracture needs to be evaluated with a high index of suspicion and proper investigations must be performed prior to fracture fixation. We present a case of primary leiomyosarcoma of humerus, who presented as pathological fracture and underwent inadvertent plating at a peripheral hospital. We treated this patient with wide resection of the tumor and the reconstruction was performed with an implant (Kuntscher’s nail and extra-articular plate) with bone cement spacer. The use of this novel method allowed us to perform implant fixation with small distal humerus bone segment and preserve native elbow joint. In this case report, we aim to highlight the importance of thorough preoperative evaluation and keeping a high index of suspicion while dealing with suspected pathological fractures to differentiate between primary and metastatic disease.

Percutaneous Tibial Fracture Reduction Using Computed Tomography Imaging, Computer Modelling and 3D Printed Alignment Constructs: A Cadaveric Study.

The main aim of this study was to evaluate a percutaneous method of bone alignment using a diaphyseal tibial fracture model. Mid-shaft diaphyseal fractures were created in 12 large-breed canine tibiae. Interaction pins were inserted into the proximal and distal bone segments. Computed tomography scans of the fractured tibiae and pins were imported into three-dimensional (3D) modelling software and the fractures were virtually reduced. A multi-component 3D printed alignment jig was created that encompassed the pins in their aligned configuration. Orthogonal radiographs were taken after alignment jig application. Intact and post-alignment tibial lengths and joint angles were compared. Rotational alignment was subjectively evaluated. Post-alignment tibial lengths differed on the mediolateral and craniocaudal radiographs by an average of 1.55 and 1.43% respectively. Post-alignment mechanical medial proximal tibial angle, mechanical medial distal tibial angle and mechanical caudal proximal tibial angle had an average difference of 1.67°, 1.92° and 2.17° respectively. Differences in tibial length and joint angles were not significant (p > 0.05). While in vivo evaluation is necessary, this technique to align diaphyseal fractures percutaneously using computer modelling and 3D printing is technically feasible and may facilitate the clinical use of minimally invasive osteosynthesis techniques.

Femoral Osteosynthesis in Black Capuchin Monkey (Sapajus nigritus) using Locking Plate

Background: Locking bone plates for internal fixation are characterized by plates with a locknut by screwing in a threaded chamber. The increased stability associated with less vascular lesion contribute to the lower risk of complications and makes the locking bone plates especially interesting in fracture management of wild animals to be reintroduced into nature.The aim of this report is to describe the case of a black capuchin monkey with a femoral fracture, submitted to internal fixation using locking plate, with a satisfactory postoperative evolution, characterized by the bone consolidation and full recovery of the function of the member.Case: An exemplar of an adult male black capuchin monkey (Sapajus nigritus) with 4.2 kg of body weight was presented due to a comminuted, diaphyseal fracture of the left femur. The animal was then submitted to internal fixation of the femoral fracture using a 2.0 mm locking plate with 11 holes. For the internal fixation, the plate was contoured and positioned on the lateral surface of the bone. In addition, four locking screws were inserted through both cortices in the proximal bone segment, while other three locking screws were inserted in the distal bone segment. Two of the distal locking screws were inserted through both bone cortices, while one of them were inserted through only one bone cortical. The animal showedcomplete functional recovery of the left hind limb at 30 days postoperatively. Despite this, it was visualized at the radiographic examination a partial release of the plate from the distal bone segment. Due to this, the animal was submitted to another surgical intervention to replace the distal locking screws by bicortical locking screws. The animal showed hind limb weight support at the second day postoperatively. The complete functional recovery of the left hind limb, however, was verified at 26 days postoperatively. In this moment, it was performed a new radiographic examination, which allowed the visualization of bone consolidation, and the animal was reintroduced into its natural habitat.Discussion: The choice of the bone plate may play a fundamental role in the bone healing process. Among many bone plates configuration, locking plates are highlighted, as they offer greater angular stability to the fracture and result in less injuring periosteum and blood vessels. In addition, other methods for internal fixation are related to numerous postoperative complications. Despite the low rate of complications of the locking system, in the present case, it was visualized the partial release of the plate from the distal bone segment, which is probably related to the higher concentration of load near the sniffle joint, and the early release of one monocortical screw. The use of monocortical screws is permissible whenproperly locked in the threaded chambers of the plate. In the present case, however, it is believed that the early release of the distal monocortical screw is probably related to the incompletely screw head locked in the threaded chamber of the plate. Therefore, the use of bicortical screws should be preferred even using locking systems, especially in anatomical regions subjected to a higher concentration of load, as near the sniffle joint. In addition, it is concluded that the locking plate maybe a viable option for the treatment of long bone fractures in wild animals, in particular femoral fractures of specimens of black capuchin monkey (Sapajus nigritus).Keywords: wild animals, internal fixation, fracture.

Temporomandibular joint regeneration: proposal of a novel treatment for condylar resorption after orthognathic surgery using transplantation of autologous nasal septum chondrocytes, and the first human case report

BackgroundUpon orthognathic mandibular advancement surgery the adjacent soft tissues can displace the distal bone segment and increase the load on the temporomandibular joint causing loss of its integrity. Remodeling of the condyle and temporal fossa with destruction of condylar cartilage and subchondral bone leads to postsurgical condylar resorption, with arthralgia and functional limitations. Patients with severe lesions are refractory to conservative treatments, leading to more invasive therapies that range from simple arthrocentesis to open surgery and prosthesis. Although aggressive and with a high risk for the patient, surgical invasive treatments are not always efficient in managing the degenerative lesions.MethodsWe propose a regenerative medicine approach using in-vitro expanded autologous cells from nasal septum applied to the first proof-of-concept patient. After the required quality controls, the cells were injected into each joint by arthrocentesis. Results were monitored by functional assays and image analysis using computed tomography.ResultsThe cell injection fully reverted the condylar resorption, leading to functional and structural regeneration after 6 months. Computed tomography images showed new cortical bone formation filling the former cavity space, and a partial recovery of condylar and temporal bones. The superposition of the condyle models showed the regeneration of the bone defect, reconstructing the condyle original form.ConclusionsWe propose a new treatment of condylar resorption subsequent to orthognathic surgery, presently treated only by alloplastic total joint replacement. We propose an intra-articular injection of autologous in-vitro expanded cells from the nasal septum. The proof-of-concept treatment of a selected patient that had no alternative therapeutic proposal has given promising results, reaching full regeneration of both the condylar cartilage and bone at 6 months after the therapy, which was fully maintained after 1 year. This first case is being followed by inclusion of new patients with a similar pathological profile to complete an ongoing stage I/II study.Trial registrationThis clinical trial is approved by the National Commission of Ethics in Medical Research (CONEP), Brazil, CAAE 12484813.0.0000.5245, and retrospectively registered in the Brazilian National Clinical Trials Registry and in the USA Clinical Trials Registry under the Universal Trial Number (UTN) U1111–1194-6997.

Three-dimensional Analysis and Evaluation in Orthognathic Surgical Cases with Facial Asymmetry.

Two-dimensional cephalometric analysis is commonly used in planning and evaluating the outcome of orthognathic surgery. It is difficult to arrive at an accurate evaluation with this method, however, as the jaw bones overlap in profile. Therefore, the purpose of this study was to use 3-dimensional (3-D) orthognathic treatment planning software for measurement of distances and angles to evaluate change in dentofacial morphology and stability after orthognathic surgery in patients with jaw deformity and facial asymmetry. Computed tomography with SimPlant O&O® (Materialize Dental, Belgium) was used to obtain data at before surgery (T1) and at 1 month (T2) and 1-2 years postoperatively (T3). Reference points, reference planes, and evaluation items were set to measure angles and distances. The average values at T1, T2, and T3 and the standard deviations were obtained. The analyses of change in distance and angle between T1 and T2 in both the maxilla and mandible revealed that the amount of postoperative deviation and change was greatest in the mandible (p<0.05). These findings showed a correlation between postoperative change in position of the chin and symmetry. Only a minimal amount of change was observed between T2 and T3 in both the maxilla and mandible. The results also revealed a correlation between positional change in both the proximal and distal bone segments and stability. It was found to be possible to determine change in horizontal, vertical, and anterior/posterior angle in both the maxilla and mandible by such 3-D analysis. The results suggest that the chin is the most appropriate facial element for evaluation of symmetry after orthognathic surgery.

Three-dimensional Finite Element Analysis of Bone Fixation in Bilateral Sagittal Split Ramus Osteotomy Using Individual Models

The purpose of this study was to investigate factors involved in stress on locking mini-plate/screws used in orthognathic surgery based on patient-specific 3-dimensional finite element analysis. Data were obtained from 10 patients undergoing mandibular advancement by bilateral sagittal split ramus osteotomy. All underwent osteosynthesis with 2.0-mm titanium locking mini-plate/screws. A 3-dimensional finite element model of the mandible was created for each patient and each model subjected to the same loading conditions, which produced different stress values on locking mini-plate/screws. When the contact area of the proximal and distal bone segments was narrower and bone mineral density (BMD) lower, the von Mises stress values on the plate/screws were higher (contact area, p<0.01; BMD, p<0.05). The present results suggest that bone contact area and BMD should be considered as plate stress factors.

Impact insertion of osteochondral grafts: Interference fit and central graft reduction affect biomechanics and cartilage damage.

An osteochondral graft (OCG) is an effective treatment for articular cartilage and osteochondral defects. Impact of an OCG during insertion into the osteochondral recipient site (OCR) can cause chondrocyte death and matrix damage. The aim of the present study was to analyze the effects of graft-host interference fit and a modified OCG geometry on OCG insertion biomechanics and cartilage damage. The effects of interference fit (radius of OCG - radius of OCR), loose (0.00 mm), moderate (0.05 mm), tight (0.10 mm), and of a tight fit with OCG geometry modification (central region of decreased radius), were analyzed for OCG cylinders and OCR blocks from adult bovine knee joints with an instrumented drop tower apparatus. An increasingly tight (OCG - OCR) interference fit led to increased taps for insertion, peak axial force, graft cartilage axial compression, cumulative and total energy delivery to cartilage, lower time of peak axial force, lesser graft advancement during each tap, higher total crack length in the cartilage surface, and lower chondrocyte viability. The modified OCG, with reduction of diameter in the central area, altered the biomechanical insertion variables and biological consequences to be similar to those of the moderate interference fit scenario. Micro-computed tomography confirmed structural interference between the OCR bone and both the proximal and distal bone segments of the OCGs, with the central regions being slightly separated for the modified OCGs. These results clarify OCG insertion biomechanics and mechanobiology, and introduce a simple modification of OCGs that facilitates insertion with reduced energy while maintaining a structural interference fit. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:377-386, 2018.