Body Osteotomy Research Articles

Technical Note on the Role of Kambin's Triangle in the Evolution of Total Joint Replacement of the Lumbar Spine.

We provide a historical and technical perspective on the evolution of Kambin's triangle as a safe working corridor for percutaneous access to the intervertebral disc to an anatomically expanded space to accommodate and facilitate open lumbar total joint replacement. The nearly 6-decade progression from intradiscal access in the intact lumbar spine to an enlarged working space following facetectomy to accommodate a transforaminal lumbar interbody fusion, and eventual further expansion via pedicle vertebral body osteotomy to support motion preservation with total joint replacement, represents a unique evolutionary pathway in surgical technique development. For each of these steps in evolution, we detail and provide the historical context of the corresponding surgical modifications required to expand the original anatomical boundaries of Kambin's triangle. It is postulated that the introduction of machine learning technologies coupled with innovations in robotics, materials science, and advanced imaging will further accelerate and refine the adaptation of more complex, precise, and efficacious surgical procedures to treat spinal degeneration via this working corridor.

Mandibular Body Osteotomy Combined with Sagittal Split Ramus Osteotomy for the Treatment of Severe Skeletal Class Ⅲ Malocclusion with Ankylosed Teeth.

This study presents a combination of 2 different surgery procedures performed on the mandible as part of the treatment aiming to improve the facial profile and occlusal function of patients with severe skeletal class Ⅲ malocclusion and bilateral edentulous gaps. The teeth next to the edentulous gaps were found to be ankylosed. Mandibular setback by bilateral sagittal split ramus osteotomies and mandibular body osteotomies, combined with Le Fort Ⅰ level maxillary advancement were performed, since the chief complaint of the patient was a concave profile. As a result, the skeletal class Ⅲ malocclusion had been corrected, a satisfying facial profile had been achieved, and no apparent adverse effect was found. Thus, it has been proved that the combination of sagittal split ramus osteotomy and mandibular body osteotomy is available for correcting skeletal class Ⅲ malocclusion.

Aesthetic Enhancement of the Gonial Angle and Inferior Mandibular Border in the Chinese Population.

The current absence of a standardized mandibular body osteotomy design poses challenges in surgical planning. Traditional approaches may not suit patients with wider anterior mandibles, potentially resulting in unsatisfactory outcomes. Addressing this issue requires a rational design that combines mandibular angle and body osteotomies for improved clinical practice. In this retrospective cohort study we aimed to analyze mandibular computed tomography (CT) data with digital methods. The goal was to establish an integrated osteotomy design for both mandibular angle and body procedures and classify prevalent mandibular types in the Chinese Han population for surgical guidance. Included were 89 patients who underwent mandibular angle osteotomy without genioplasty between 2016 and 2022 at Peking University Third Hospital. Mimics 21.0 software facilitated CT data reconstruction and osteotomy planning. Postoperative effects were assessed through imaging, complications, and surveys, leading to mandibular type classification. Mandibular angles were categorized by 3 types, based on osteotomy range. Type I involved mandibular body osteotomy only, type II mandibular angle osteotomy only, and type III both mandibular angle and body osteotomies. Distribution within the cohort was 2.25%, 8.99%, and 88.76% for types I, II, and III respectively. Patient satisfaction was high, with minor and major complications at 47.19% and 1.12% by Clavien-Dindo classification. Utilizing Mimics software, we established an integrated osteotomy design and categorized mandibular types. Findings offer valuable guidance for mandibular angle surgery and contribute to understanding of Asian mandibular morphology.

Stability of different fixation methods after reduction malarplasty under average and maximum masticatory forces: a finite element analysis

BackgroundAlthough titanium plates/screws are effective fixation methods (FM) after L-shaped osteotomy reduction malarplasty (LORM), the ideal FM remains controversial. This first finite element analysis (FEA) aimed to study the effect of various zygomatic body/zygomatic arch FM combinations and their placement vectors on the zygoma complex stability after virtual LORM under the effect of both average (150 N/mm2) and maximum (750 N/mm2) forces and three-dimensional (3D) mapping of stress and strain parameters distribution over the zygomatic bone, fixation methods, and total model.ResultsThe fixation methods about the short-arm of the L-shaped osteotomy showed lower stress, strain, and displacement values than those across the long-arm osteotomy site. Combined with any zygomatic arch fixation methods (ZAFm), the two bicortical screws group (2LS) on the zygomatic body osteotomy site resulted in smaller displacements and the lowest zygoma bone stress and displacement when combined with Mortice–Tenon structure (MT) as zygomatic arch fixation method. Applied forces caused statistically significant differences in zygomatic bone stress (P < 0.001 and P = 0.001) and displacement (P = 0.001 and P = 0.002).ConclusionAll FMs both on the zygomatic body and zygomatic arch provide adequate zygomatic complex stability after LORM. The 2LS group showed better resistance than rectangular plate (RP) and square plate (SP) with lower stress concentrations. The L-shaped plate with short-wing on the maxilla (LPwM) is more stable than having the short-wing on the zygoma bone (LPwZ). Future prospective clinical studies are required to validate the current findings.

Application of vertebral body compression osteotomy in pedicle subtraction osteotomy on ankylosing spondylitis kyphosis: Finite element analysis and retrospective study.

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease, with pathological characteristics of bone erosion, inflammation of attachment point, and bone ankylosis. Due to the ossified intervertebral disc and ligament, pedicle subtraction osteotomy (PSO) is one of the mainstream surgeries of AS-related thoracolumbar kyphosis, but the large amount of blood loss and high risk of instrumental instability limit its clinical application. The purpose of our study is to propose a new transpedicular vertebral body compression osteotomy (VBCO) in PSO to reduce blood loss and improve stability. A retrospective analysis was performed on patients with AS-related thoracolumbar kyphosis who underwent one-level PSO in our hospital from February 2009 to May 2019.A total of 31 patients were included in this study; 6 received VBCO and 25 received eggshell vertebral body osteotomy. We collected demographic data containing gender and age at diagnosis. Surgical data contained operation time, estimated blood loss (EBL), and complications. Radiographic data contained pre-operative and follow-up sagittal parameters including chin brow-vertical angle (CBVA), global kyphosis (GK), thoracic kyphosis (TK), and lumbar lordosis (LL). A typical case with L2-PSO was used to establish a finite element model. The mechanical characteristics of the internal fixation device, vertebral body, and osteotomy plane of the two osteotomy models were analyzed under different working conditions. The VBCO could provide comparable restoring of CBVA, GK, TK, and LL in the eggshell osteotomy procedure (all p > 0.05). The VBCO significantly reduced EBL compared to those with eggshell osteotomy [800.0ml (500.0-1,439.5 ml) vs. 1,455.5 ml (1,410.5-1,497.8 ml), p = 0.033]. Compared with the eggshell osteotomy, VBCO showed better mechanical property. For the intra-pedicular screw fixation, the VBCO group had a more average distributed and lower stress condition on both nails and connecting rod. VBCO had a flattened osteotomy plane than the pitted osteotomy plane of the eggshell group, showing a lower and more average distributed maximum stress and displacement of osteotomy plane. In our study, we introduced VBCO as an improved method in PSO, with advantages in reducing blood loss and providing greater stability. Further investigation should focus on clinical research and biomechanical analysis for the application of VBCO.

3D-Printed Guide Plate System-Assisted Thoracolumbar Kyphosis Osteotomy: A Technical Case Series

This paper reports a new three-dimensional (3D)-printed osteotomy guidance system to assist thoracolumbar kyphosis osteotomy and describe the guide plate design, surgical procedure, and short-term clinical results. The computer-aided design software reconstructs the 3D model of the spinal deformity region using the computed tomography data of the patient and plans the correction angle according to the deformity. The guide plate design described in previous experimental studies was used and optimized before clinical application. The lamina positioning, lamina osteotomy, and vertebral osteotomy guides were designed, and three 3D guides with different functions were used to assist osteotomy. Seven patients successfully underwent osteotomy under the guidance of a 3D guide plate. Kyphosis was corrected to different degrees without serious complications. At the last follow-up, the back pain and nerve function of 7 patients were improved to varying degrees and the internal fixation without displacement and fracture. The preliminary clinical application of the new 3D osteotomy guidance system shows that it provides an effective connection between the guide plates and a clinically operative visual field. The use of a 3D guide plate system for positioning and guidance is helpful to complete preoperative planning of anterior and middle column vertebral body osteotomy. However, the efficacy of this method should be compared to that of the free-hand technique with long-term follow-up.

Personalized 3D-printed Titanium Cutting Guide and Prefabricated Osteosynthesis Plate for Mandibular Step Osteotomy to Treat Severe Mandibular Prognathism

Mandibular step osteotomy, performed for mandibular prognathism, is a difficult and time-consuming procedure. Virtual computer surgery and computer-aided design & computer-aided manufacturing have demonstrated accurate results in orthognathic surgery, though not used for mandibular step osteotomy yet. In this study, the authors report the case of a 21-year-old man with severe mandibular prognathism, with a reverse overjet of 12 mm. Step osteotomy, a modified method of body osteotomy, was planned virtually and performed using 3-dimensional (3D) printed titanium surgical guides and osteosynthesis plates, using computer-aided design & computer-aided manufacturing. At the 6-month postoperative follow-up, there were no notable complications, and normal healing was observed. Each segment was stably in place with the prefabricated plates. The proximal segments were not sagged medially or laterally. With 3D-printed surgical guides and osteosynthesis plates, intraoperative complications, such as injury to adjacent teeth and nerves, could be avoided. They also showed reasonable accuracy and helped reduce operative time and improve outcomes. Unlike surgical guides made of resin/polyamide, titanium surgical guides can be made thinner, which can reduce the extent of detachment. They also did not undergo any deterioration during the operation. Cutting guides and prefabricated plates using virtual surgical planning and 3D printing have many advantages, including reduced preoperative preparation time and operative time, reduced incidence of intraoperative complications, and improved outcomes. However, limitations still exist and further studies are required.

Three-dimensional soft tissue changes after reduction malarplasty in female patients

The aim of this study was to determine the three-dimensional soft tissue changes after reduction malarplasty. Soft tissue changes relative to the amount of movement of the zygomatic bone were studied. Pre- and postoperative cone beam computed tomography images of 21 female patients were superimposed. The anterior-most point of the body osteotomy (point A), arch osteotomy site (point D), and points dividing line A–D into thirds (points B and C) were marked on lateral view images. The vertical distances from the midsagittal line to the centre of the zygomatic bone and the outer prominence of the soft tissue were measured on the coronal view of each image. The proportion of the change in soft tissue to that of the bone before and after surgery was calculated for each point. The relationship between body mass index and the soft tissue change ratio, and the differences in soft tissue changes at each point were analysed. Mean soft tissue changes for points A, B, C, and D were 53.43%, 66.66%, 63.67%, and 57.23%, respectively. The amount of soft tissue change at point B was greater than that at points A and D, which were osteotomy sites. There was no statistical correlation between body mass index and the soft tissue change ratio at each point.

Spinal deformity correction in ankylosing spondylitis.

Background: Ankylosing spondylitis (AS) is a complex, debilitating disease with few available medical therapies in its later stages.Methods: We reviewed current clinical approaches for caring for AS patients with an emphasis on the risks and outcomes associated with surgical intervention.Results: It is critical to understand the natural history and surgical outcomes of patient with AS. Surgery is not without risks, as a vertebral body osteotomy is often required to re-establish spinopelvic equilibrium. However, surgery can lead to clinical improvements in pain, disability, cardiac function, respiration, digestion, and sexual activity.Conclusion: Deformity correction for AS should be carefully considered in symptomatic patients.

Correlation of vertebral trabecular attenuation in Hounsfield units and the upper instrumented vertebra with proximal junctional failure after surgical treatment of degenerative lumbar disease.

The aim of this study was to investigate whether bone mineral density (BMD) measured in Hounsfield units (HUs) is correlated with proximal junctional failure (PJF). A retrospective study of 104 patients with adult degenerative lumbar disease was performed. All patients underwent posterior instrumented fusion of 4 or more segments and were followed up for at least 2 years. Patients were divided into two groups on the basis of whether they had mechanical complications of PJF. Age, sex ratio, BMI, follow-up time, upper instrumented vertebra (UIV), lower instrumented vertebra, and vertebral body osteotomy were recorded. The spinopelvic parameters were measured on early postoperative radiographs. The HU value of L1 trabecular attenuation was measured on axial and sagittal CT scans. Statistical analysis was performed to compare the difference of continuous and categorical variables. Receiver operating characteristic (ROC) curve analysis was used to obtain attenuation thresholds. A Kaplan-Meier curve and log-rank test were used to analyze the differences in PJF-free survival. Multivariate analysis via a Cox proportional hazards model was used to analyze the risk factors. The HU value of L1 trabecular attenuation in the PJF group was lower than that in the control group (p < 0.001). The spinopelvic parameter L4-S1 lordosis was significantly different between the groups (p = 0.033). ROC curve analysis determined an optimal threshold of 89.25 HUs (sensitivity = 78.3%, specificity = 80.2%, area under the ROC curve = 0.799). PJF-free survival significantly decreased in patients with L1 attenuation ≤ 89.25 HUs (p < 0.001, log-rank test). When L1 trabecular attenuation was ≤ 89.25 HUs, PJF-free survival in patients with the UIV at L2 was the lowest, compared with patients with their UIV at the thoracolumbar junction or above (p = 0.028, log-rank test). HUs could provide important information for surgeons to make a treatment plan to prevent PJF. L1 trabecular attenuation ≤ 89.25 HUs measured by spinal CT scanning could predict the incidence of PJF. Under this condition, the UIV at L2 significantly increases the incidence of PJF.

MANDIBULAR BODY OSTEOTOMY FOR SKELETAL CLASS III MALOCCLUSION: A CASE-BASED REVIEW

Mandibular step body osteotomy has been out of favour since more stable ramus osteotomies were refined and used for jaw deformities. Mandibular body osteotomy still has certain indications for which it is preferable over ramus osteotomies. Mandibular body osteotomy is best suited to correct prognathism caused by mandibular body excess with a retained tooth or in presence of extraction space, with good posterior occlusion, when ramus osteotomies and setback will lead to loss of the last tooth and non-obtuse gonial angle. Other indications are apertognathia, mandibu­lar asymmetry and small advancements of the anterior mandible. Here we present a case 24 year male with a skeletal class III malocclusion managed with an intra­oral mandibular step osteotomy and setback of 8 mm. One-year followup has shown minimum neurosensory and odontogenic complications associated with mandibular step osteotomy and very high satisfaction among the patient. We also present a brief review of the indications, modifi­cations and refinement of the technique and summarize current published clinical usage. This is a very stable osteotomy with favourable fracture pattern and does not involve stripping or change in position of muscles of mastication thereby ensures long term stability and minimal risk of relapse. This surgery also has minimal effect on airway narrowing compared to the ramus osteotomy setback. For some specific indications not suited to a sagittal split ramus osteotomy, mandibular body step osteotomy still has relevance and usage.

COMPARISON OF BONE HEALING AFTER THE USE OF A THREE DIMENSIONAL MINIPLATE AND A CONVENTIONAL MINIPLATE IN MANDIBULAR BODY OSTEOTOMY (AN EXPERIMENTAL STUDY)

Introduction: Mandibular fractures comprise most of the traumatic injuries treated by an oral and maxillofacial surgeon. The aim of fracture treatment is to restore the architecture and function of bone. Many techniques for treating mandibular fractures have evolved over the years. The design of the three dimensional (3D) plate is conceptually that of 2 linear plates connected by reinforcing vertical struts providing greater resistance against gap opening at the inferior border with biting forces. Objectives: To compare histologically bone healing of mandibular body osteotomy after using either a 3D miniplate or conventional miniplates. Materials and methods: This study was conducted on twelve healthy dogs. An iatrogenic osteotomy defect was performed intra-orally between the mandibular 3rd and 4th premolars using a surgical micro reciprocating saw. The fragments will be reduced bimanually and stabilized: Group A (six dogs): 3D miniplates. Group B (six dogs): conventional miniplates. The dogs were euthanized at 2 and 6 weeks postoperatively and the osteotomy sites were excised, divided into three thirds (Tension Third, TT; Intermediary Third, IT; Compression Third, CT) and prepared for histological analysis. Results:The osteotomy site was completely filled with parallel-fibred bone, with more newly formed Haversian systems in Group A compared with Group B, bone repair did not reach the typical aspects of the parent lamellar bone. The percentages of newly formed bone at 2 weeks in group A according to thirds (TT, IT and CT) that reported have a statistically significant difference in comparison with group B. At 6 weeks, there were no statistically significant differences between the two groups among the TT and CT but there was a statistically significant difference (p4 = 0.039) in the IT. Conclusions: 3-D plates could be a better option than conventional miniplates.

Histological Analysis of Bone Repair in Mandibular Body Osteotomy Using Internal Fixation System in Three Different Gaps without Bone Graft in an Animal Model.

The aim was to analyze histologically the bone repair in a mandibular osteotomy model with different gaps between the segments. Nine male rabbits who underwent osteotomies on the mandibular body were fixed with a 1.5 system plate and no bone graft; group 1 (2 mm gap between segments), group 2 (5 mm gap between segments), and group 3 (8 mm gap between segments) were included. After 8 weeks they were euthanized and the sample was processed for histological analysis. Group 1 showed advanced bone repair with cartilaginous tissue and cancellous bone, showing osteoblasts and type III collagenous fibers. In group 2, a more delayed ossification was observed, with an extensive area of peripheral ossifying cartilage and chondrocytes in greater number at the center of the defect; group 3 showed no evidence of ossification with fibrous tissue, a very low level of chondrocytes, and some bone sequestrate. We can conclude that, in this animal model, 2 or 5 mm gap in the osteotomy could be repaired as bone when fixation is used. The size of the gap is an important factor for the use of bone grafts considering endochondral ossification. This model can be used for graft analysis and related technologies.

S1 Pedicle Subtraction Osteotomy in Sagittal Balance Correction. A Feasibility Study on Human Cadaveric Specimens

A cadaveric feasibility study was carried out. Osteotomies to correct fixed sagittal imbalance are usually performed at L3/ L4. To investigate the feasibility of S1 pedicle subtraction osteotomy to correct spinal deformity and spinopelvic parameters, achieving better results with more limited exposure. The data obtained will allow a fixation construct specific for this osteotomy to be designed. S1 pedicle subtraction osteotomy was performed on 12 cadaveric specimens. Baseline and postprocedural computed tomography and biomechanical studies were performed. Data were analyzed with a fixation system SolidWorks model, and the redesigned fixation construct was described and analyzed with an ANSYS model. S1 pedicle subtraction osteotomy is technically feasible. The fixation can be achieved with L4, L5, and iliac screws connected with bars. The system can be reinforced with a polyetheretherketone cage placed anteriorly in the S1 body osteotomy site, a cross-connecting bar, a double iliac screw, or an anterior interbody cage placed at the L5-S1 disc. The fixation strength is improved by angulating the iliac rod channel 10°, adding a semi-sphere to the locking screw contact surface and 2 fins to its saddle. The redesigned construct showed suitable stress and deformation levels, achieving the expected biomechanical requirements. Compared with surgery on higher levels, S1 pedicle subtraction osteotomy allows greater correction with shorter fixation, because the osteotomy is performed at a more caudal level, modifying the spinopelvic parameters. S1 pedicle subtraction osteotomy is technically feasible. Finite element analysis results indicate that it has appropriate biomechanical properties.

0890 INDIVIDUALIZED THERAPY FOR TREATING OBSTRUCTIVE SLEEP APNEA IN PEDIATRIC CROUZON SYNDROME PATIENTS

Pediatric patients with Crouzon syndrome have great possibilities in suffering from obstructive sleep apnea (OSA), which is mainly due to midfacial hypoplasia and facial deformities. For most patients, a multi-disciplinary and sequential treatment plan is necessary to make for Crouzon syndrome often has different phenotypes of different severity in OSA and facial deformities. Typical patients were selected in this study to illustrate the necessity of individualized therapy for treating OSA. In the study, four Crouzon syndrome children of different severity in suffering from OSA and maxillofacial deformities were introduced. Detailed information in individualized treatment options was given including clinical manifestations, radiological findings, polysomnography detectings and treatment combinations. Based on the above findings, different but effective treatment options for these children’s OSA problems were adopted, either by surgeries including distraction osteogenesis and craniomaxillofacial surgeries with or without tonsillectomy, or by noninvasive continuous positive airway pressure (CPAP) therapy. Patient 1 was performed with LeFort IIIosteotomy and external distraction osteogenesis. Patient 2 was given LeFort IIIosteotomy and external distractor fixation and concurrent bilateral mandibular body osteotomy and internal distractor fixation for bimaxillary distraction. Patient 3 received LeFort I osteotomy for maxillary advancement with concurrent bilateral tonsillectomy. Differently, patient 4 with mild OSA disturbance adopted initial continuous positive airway pressure (CPAP) with good adherence and body development. Six years later, he began orthodontic treatment for preparing for orthognathic surgery. Recently bimaxillary surgery was performed on him to enlarge upper airway anatomically as well as improve facial profile. Follow-up studies showed problems of OSA and nocturnal hypoxia of those four patients were all alleviated greatly, as well as maxillofacial deformities. Combined with preoperative and postoperative orthodontics, patient 1 and 4 also got optimal results in better facial profile and dental occlusion. Thus, given Crouzon patients had great possiblilities in suffering from OSA and hypoxia problems, individualized therapy should be made and performed carefully to obtain optimized treatment results based on adequate clinical evaluations and patients’ conditions including age, disease severity and esthetic considerations. This work was supported by the National Natural Science Foundation of China (Grant number: 81470786).

Reduction Gonioplasty: Bone Regeneration and Soft Tissue Response.

Reduction gonioplasty is frequently used to achieve an oval-shaped face in Asia. However, the soft tissue response and bone regeneration of reduction gonioplasty which are keys to the outcome are still unclear. The aim of this study is to evaluate the effects of bone regeneration on facial width and the soft tissue response of reduction gonioplasty. We retrospectively reviewed patients who underwent reduction gonioplasty from 2009 to 2013. A high-speed rotary cutting bur without a water coolant was routinely used from the new gonial point to the inferior mandibular rim under the second premolar, whereas the elongated osteotomy line (mandibular-chin body osteotomy) was performed with a reciprocating saw. Forty-nine patients with preoperative, immediate postoperative, and 12-month postoperative frontal cephalograms were included in our study. Mandible and soft tissue profiles were measured on cephalograms. Bone regeneration in high-speed rotary cutting bur ostectomy region was -0.79 ± 1.76 mm (1 cm above Go-Go), -0.75 ± 1.46 mm (Go-Go, bigonial line), and -0.77 ± 2.10 mm (1 cm below Go-Go), whereas 0.07 ± 1.79 mm (2 cm below Go-Go) in ostectomy region performed by reciprocating saw. The soft tissue response ratios were 76.72 ± 30.70% (Go-Go), 108.8 ± 54.11% (1 cm below Go-Go), and 155.9 ± 66.82% (2 cm below Go-Go). Bone regeneration does not lead to an increase in facial width after reduction gonioplasty with our technique, and the use of a high-speed rotary cutting bur without a water coolant decreases bone regeneration. The soft tissue response ratio is higher in the anterior mandible, and the outcome of reduction gonioplasty is a sharper lower face with a full cheek. Reduction gonioplasty is an effective and predictable lower face reshaping surgery.

Bone healing after biodegradable mini-plate fixation.

To compare bone healing in mandibular vertical body osteotomies (MVBO) after fixation with a resorbable 2.0mm-profile fixation system in the first and third postoperative months in rabbits. Twenty hemimandibles of ten rabbits were divided into two groups according to duration of resorbable fixation-one or three months. The MVBOs were performed and one four-hole, resorbable, 2.0mm mini-plate fixation system was used on each side. The computed tomography (CT) scans, scanning electron microscopy (SEM), and histomorphometric outcomes of groups I and II were compared. Significant differences were found between the one- and three- month assessments in terms of newly formed bone ratio values (p<0.05). There was more new bone formation at the third month on both the CT and histomorphometric examinations. A better adaptation of the bone tissues to the resorbable mini-plate and screws was observed on SEM at three months. The resorbable mini-plates provided a fixation stable enough to allow immediate oral alimentation and callus formation in both groups.

Histologic and Histometric Analysis of Bone Repair at the Site of Mandibular Body Osteotomy and at the Bone-Screw Interface After Using a Biodegradable 2.0-mm Internal Fixation System.

The aim of the study was to evaluate histologically and histometrically the bone repair at the mandibular body osteotomy and at the bone-screw interface after using a biodegradable 2.0-mm internal fixation system. Six dogs were subjected to an osteotomy in the mandibular body, which was stabilized by applying a fixation device manufactured with poly-L-DL-lactic acid (70:30). The dogs were euthanized at 2 and 18 weeks. Each screw was sectioned along its long axis, and the osteotomy sites were divided into 3 parts: the upper part was labeled the tension third (TT); the lower part, compression third (CT); and the part between the TT and CT, intermediary third (IT). Histologic analysis showed areas of direct contact between the screw surface and the parent lamellar bone at 2 weeks. At 18 weeks, 3 microscopically distinct layers at the bone-screw interface were noted. At the osteotomy sites, union between the bone fragments was observed at 18 weeks. Statistically significant differences in the newly formed bone among TT, IT, and CT (P = 0.019) were observed. In conclusion, the biomechanical environment created by the biodegradable IF system used in this study facilitated bone repair at the osteotomy site.

V-Y vertebral body osteotomy for the treatment of fixed sagittal plane spinal deformity

Background contextFixed sagittal plane imbalance (FSI) has traditionally been corrected by either opening or closing wedge osteotomies or vertebral column resections. These methods involve multiple vertebrae and have been associated with limited degrees of correction and/or neurovascular compromise. PurposeWe describe a new V-Y vertebral osteotomy (VYO) that involves a single vertebra, allowing for correction of all three columns in a safer fashion. Study designA prospective assessment of the degree of correction pre- and post-VYO in a tertiary spinal center. Patient sampleTen consecutive patients presenting with sagittal plane imbalance were enrolled in this study. Outcome measuresOutcomes were assessed with pre- (preop) and postoperative (postop) outcome questionnaires (Oswestry Disability Index [ODI] and Scoliosis Research Society-24) and radiography. MethodsTen patients underwent VYO at L3 with varying levels of instrumentation. The procedure involves a V-shaped osteotomy in the sagittal plane, sparing the anterior 50% of the body, the apex of which is then converted to a Y shape, and the osteotomy closed. ResultsPatients were followed for a mean of 36 months (24–48 months). The procedure led to significant improvements in sagittal balance, lumbar lordosis, thoracic kyphosis, coronal balance, sacral inclination, and pelvic incidence. The average degree of correction achieved was 44.58°±6.19° (mean±standard deviation). The mean blood loss was 1,287±350 mL and the operative time was 220±24 minutes. The mean preop ODI was 72% (range 58%–85%) and postop ODI averaged 22% (range 10%–30%). The mean preop SRS-24 score was 30.1 and postop was 101. ConclusionsThe VYO provides a safe correction of up to 45° at a single osteotomy site in FSI patients. It involves an isolated posterior approach and is recommended for corrections below the region of the conus.

Anin vitrocomparison between two different designs of sagittal split ramus osteotomy

ObjectivesTo evaluate the influence of the type of osteotomy in the inferior aspect of the mandible on the mechanical performance.Materials and MethodsThe study was performed on 20 polyurethane hemimandibles. A sagittal split ramus osteotomy (SSRO) was designed in 10 hemimandibles (group 1) with a vertical osteotomy in the buccal side (second molar level) and final osteotomy was performed horizontally on the lingual aspect, while the mandible body osteotomy was finalized as a straight osteotomy in the basilar area, perpendicular to the body. For group 2, the same osteotomy technique was used, but an oblique osteotomy was done in the basilar aspect of the mandibular body, forming continuity with the sagittal cut in the basilar area. Using a surgical guide, osteosynthesis was performed with bicortical screws using an inverted L scheme. In both groups vertical compression tests were performed with a linear load of 1 mm/min on the central fossa of the first molar and tests were done with models made from photoelastic resin. Data were analyzed using Student's t-test, establishing a statistical significance when P <0.05.ResultsA statistical difference was not observed in the maximum displacements obtained in the two osteotomies (P <0.05). In the extensiometric analysis, statistically significant differences were identified only in the middle screw of the fixation. The photoelastic resin models showed force dissipation towards the inferior aspect of the mandible in both SSRO models.ConclusionWe found that osteotomy of the inferior aspect did not influence the mechanical performance for osteosynthesis with an inverted L system.