Postoperative 3D Models Research Articles

Effect of condylar rotation on the stress environment of the temporomandibular joint in patients with mandibular protrusion

PurposeThe study aims to analyse the effects of condylar rotation on the biomechanical environment of the TMJ after bilateral sagittal split ramus osteotomy (BSSRO) through the finite element method (FEM). MethodsThirteen patients with mandibular prognathism and twenty-three normal subjects were recruited. The three-dimensional (3D) models were reconstructed. 13 representative morphological parameters were measured for comparison. A patient was selected to perform virtual BSSRO surgery by rotating the condyles in MIMICS. The preoperative and postoperative 3D models of the patient were subsequently imported into ABAQUS for finite element analysis. The preoperative and postoperative stresses and joint spaces in the TMJs were investigated. ResultsThe maxillofacial morphologies of the patients with mandibular protrusion was significantly different from those of the asymptomatic subjects (P<.05). Stresses in the postoperative group were lower than those in the preoperative group. The rotation of the condyle could cause the variations in stress levels and joint spaces within the TMJs. Inward and upward rotation of the condyle was associated with higher stress in the TMJ, whereas the lowest stress was observed when the condyle remained stationary following surgical intervention. SignificanceLateral, medial and superior joint spaces were more related to the stresses in the TMJs. The condyle should be kept in place as much as possible to avoid disrupting the balance of the TMJ in patients with mandibular protrusion.

Cutting guides in mandibular tumor ablation: Are we as accurate as we think?

PurposeTumor margin status is critical in local tumor recurrence and is a significant prognostic factor in head and neck cancer survival. With the introduction of computer-assisted surgical planning, one of the main challenges is the accurate positioning of the surgical cutting guide but there is limited evidence of the accuracy of the 3D cutting guides in mimicking virtually planned osteotomy. This study evaluates the accuracy of osteotomy lines produced by 3D-printed cutting guides and assesses the overall accuracy of mandibular reconstruction. Material and MethodsThe pre and postoperative 3D models were aligned using an automated surface registration feature based on the iterative closest point algorithm. The differences in osteotomy line deviation, linear and angle measurements, and 3D volume quantification of the pre and post models were measured. ResultsWe included 14 patients (8 men and 6 women with ages ranging from 13 to 75 years) with a segmental mandibular resection who met all of the inclusion criteria. The smallest defect size was 4.4 cm, the largest defect was 12.2 cm, and the average was 7.30 cm +/- 2.80 cm. The average deviation between virtually planned osteotomy and actual surgical osteotomy was 1.52 +/-1.02 mm. No covariates were associated with increased inaccuracy of the 3D-printed cutting guides. ConclusionThe finding of this study suggests that virtual surgical planning is an unambiguous paradigm shift in the predictability of the surgical plan and achievement of the reconstruction goals. The 3D-printed cutting guides are a very accurate and reliable tool in translating virtual ablation plans to an actual surgical resection margin.

Volume Redistribution of the Buccal Fat Pad After Reduction Malarplasty.

During reduction malarplasty, cheek bulging could be found immediately after zygomatic complex is moved inwards, backwards and upwards. As patient is in the supine position during surgery, the effect of gravity is eliminated, so the only reason for the bulge is the redistribution of the soft tissue in the deep facial spaces. The buccal fat pad, with its main body behind the zygomatic arch and buccal extension in the cheek area, is most likely to be responsible for the bulge. 3D buccal extension models were reconstructed from preoperative and long-term follow-up CT images and the volume measured. By comparing the pre- and postoperative 3D models, the shape deviation of the buccal extension and facial soft tissue can be identified. Eleven patients (22 buccal extensions) met the inclusion criteria. Compared with the preoperative buccal extension volume, the postoperative volume increased significantly. By comparing the reconstructed models, the buccal extension volume increase with anteroinferior protrusion can be visually detected, and cheek bulging was clearly identified on the lower face. The bulging area coincided with the projection of the buccal extension on the skin surface. Reduction malarplasty may cause volume redistribution of the buccal fat pad. Therefore, preoperative assessment of the size of the buccal fat pad based on CT images is recommended. The buccal extension volume increase with anteroinferior protrusion is an important cause of postoperative cheek bulging and should be considered during treatment. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

3D accuracy and clinical outcomes of corrective osteotomies with patient-specific instruments in complex upper extremity deformities: an approach for investigation and correlation

BackgroundCorrective osteotomies of the upper extremities with patient-specific instruments (PSIs) are increasingly used. In this context, the concordance between planning and postoperative 3D radiographs as well as the association between 3D accuracy and clinical outcome has rarely been evaluated. In this pilot study, we aimed to investigate our clinical mid-term outcome and 3D accuracy as well as their possible correlation, including identifying aspects critical to reaching optimal correction results.MethodsFrom October 2018 to January 2020, we used PSIs for 12 corrective osteotomies of the upper extremity in 11 bones of 8 patients (congenital or posttraumatic deformities in 2 elbows, 3 forearms, 3 distal radii). In follow-up examination (10–25 months postoperatively), patient satisfaction, grip strength, ROM, VAS, and DASH were evaluated. Three-dimensional radiological accuracy was determined with 3D-reconstructed postoperative CT scans. With the software tool “Part Comparison” of Mimics® Innovation Suite Software/Materialise, surface differences of pre-planned and postoperative 3D models were compared.ResultsCompared to the preoperative situation pain and function were better at follow-up: The average VAS score significantly decreased from 6.5 ± 4.1 cm preoperatively to 2.3 ± 2.6 cm at the follow-up time point (p = 0.008). The average DASH score significantly improved, from 48.4 ± 30.9 to 27.0 ± 25.2 (p = 0.015). In the part comparison analysis “planned vs postoperative comparison”, significantly more points in percent (= 3D accuracy) were in a −3 mm to 3 mm interval than in the “preoperative vs planned comparison” (87.3 ± 13.8% vs 48.9 ± 16.6%, p = 0.004). After surgery, the maximum deviation value over all cases was 4.5 ± 1.1 mm, and the minimum deviation value was − 4.5 ± 1.2 mm vs preoperatively 12.9 ± 6.2 mm (p = 0.004) and − 7.2 ± 2.1 mm (p = 0.02), respectively. Clinically, in all cases with higher accuracy (> 90%), an improvement of either DASH or VAS or both of > 60% to the preoperative values occurred. There was a significant correlation between accuracy (%) and ΔVAS (p = 0.004). There were no method-related complications.ConclusionsOur data after PSI-based corrective osteotomy in complex deformities of the upper extremity in a limited number of cases indicate a positive correlation between 3D accuracy and clinical outcomes. Examination of 3D accuracy to analyse sources of error in the hole procedure from initial CT scan to end of surgery even in patients with not fully satisfactory clinical results is required for further development of the method to achieve optimal correction results with nearly 100% congruence between the planned and postoperative 3D bone position.Trial registration This retrospective study was registered in the Center for Translational & Clinical Research Aachen (CTC-A) with the number 20-514 on November 20, 2021

Utilizing a novel radiographic image segmentation method for the assessment of periodontal healing following regenerative surgical treatment.

The aim of the current article was to present a radiographic method to determine the surface area of newly formed periodontal attachment, as well as to analyze volumetric and morphologic changes after regenerative periodontal treatment. In this retrospective study, 11 singular intrabony periodontal defects were selected for minimally invasive surgical treatment and 3D evaluation. 3D virtual models were acquired by the segmentation of pre- and postoperative CBCT scans. This study determined the surface area of baseline periodontal attachment (RSA-A) and defect-involved root surface (RSA-D) on the preoperative 3D models, and the surface area of new periodontal attachment (RSA-NA) on the postoperative models. Finally, cumulative change of periodontal attachment (∆RSA-A) was calculated and Boolean subtraction was applied on pre- and postoperative 3D models to demonstrate postoperative 3D hard tissue alterations. The average RSA-A was 84.39 ± 33.27 mm2, while the average RSA-D was 24.26 ± 11.94 mm2. The average surface area of RSA-NA after regenerative periodontal surgery was 17.68 ± 10.56 mm2. Additionally, ∆RSA-A was determined to assess the overall effects of ridge alterations on periodontal attachment, averaging 15.53 ± 12.47 mm2, which was found to be statistically significant (P = .00149). Lastly, the volumetric hard tissue gain was found to be 33.56 ± 19.35 mm3, whereas hard tissue resorption of 26.31 ± 38.39 mm3 occurred. The proposed 3D radiographic method provides a detailed understanding of new periodontal attachment formation and hard tissue alterations following regenerative surgical treatment of intrabony periodontal defects.

Suture button versus syndesmotic screw in ankle fractures - evaluation with 3D imaging-based measurements

BackgroundInadequate reduction of syndesmotic injuries can result in disabling clinical outcomes. The aim of the study was to compare syndesmosis congruity after fixation by syndesmotic screws (SYS) or a suture button system (SBS) using three-dimensional (3D) computed imaging techniques.MethodsIn a retrospective single-center study, patients with unilateral stabilization of an ankle fracture with a syndesmotic injury and post-operative bilateral CT scans were analyzed using a recently established 3D method. The side-to-side differences were compared for tibio-fibular clear space (∆CS), translation angle (∆α), and vertical offset (∆z) among patients stabilized with syndesmotic screws or suture button system. Syndesmotic malreduction was defined for ∆CS > 2 mm and for |∆α| > 5°. ∆CS and ∆α were correlated with two-dimensional (2D) measurements.ResultsEighteen patients stabilized with a syndesmosis screw and 29 stabilized with a suture button system were analyzed. After stabilization, both groups revealed mild diastasis (SYS: mean ∆CS 0.3 mm, SD 1.1 mm vs SBS: mean ∆CS 0.2 mm, SD 1.2 mm, p = 0.710). In addition, both stabilization methods showed slight dorsalization of the fibula (SYS: mean ∆α 0.5°, SD 4.6° vs SBS: mean ∆α 2.1°, SD 3.7°, p = 0.192). Also, restoration of the fibula-to-tibia length ratio also did not differ between the two groups (SYS: mean Δz of 0.5 mm, SD 2.4 mm vs SBS: mean Δz of 0 mm, SD 1.2 mm; p = 0.477). Malreduction according to high ∆α was most common (26% of cases), with equal distribution between the groups (p = 0.234). ∆CS and ∆α showed good correlation with 2D measurements (ρ = 0.567; ρ = 0.671).ConclusionThis in vivo analysis of post-operative 3D models showed no differences in immediate post-operative alignment after syndesmotic screws or suture button system. Special attention should be paid to syndesmotic malreduction in the sagittal orientation of the fibula in relation to the tibia in radiological control of the syndesmotic congruity as well as intra-operatively.

Accuracy of Computer-Assisted Surgery in Maxillary Reconstruction: A Systematic Review.

Computer-assisted surgery (CAS) in maxillary reconstruction has proven its value regarding more predictable postoperative results. However, the accuracy evaluation methods differ between studies, and no meta-analysis has been performed yet. A systematic review was performed in the PubMed, Embase, and Cochrane Library databases, using a Patient, Intervention, Comparison and Outcome (PICO) method: (P) patients in need of maxillary reconstruction using free osteocutaneous tissue transfer, (I) reconstructed according to a virtual plan in CAS software, (C) compared to the actual postoperative result, and (O) postoperatively measured by a quantitative accuracy assessment) search strategy, and was reported according to the PRISMA statement. We reviewed all of the studies that quantitatively assessed the accuracy of maxillary reconstructions using CAS. Twelve studies matched the inclusion criteria, reporting 67 maxillary reconstructions. All of the included studies compared postoperative 3D models to preoperative 3D models (revised to the virtual plan). The postoperative accuracy measurements mainly focused on the position of the fibular bony segments. Only approximate comparisons of postoperative accuracy between studies were feasible because of small differences in the postoperative measurement methods; the accuracy of the bony segment positioning ranged between 0.44 mm and 7.8 mm, and between 2.90° and 6.96°. A postoperative evaluation guideline to create uniformity in evaluation methods needs to be considered so as to allow for valid comparisons of postoperative results and to facilitate meta-analyses in the future. With the proper validation of the postoperative results, future research might explore more definitive evidence regarding the management and superiority of CAS in maxillary and midface reconstruction.

Computed tomographic evaluation of glenoid joint line restoration with glenoid bone grafting and reverse shoulder arthroplasty in patients with significant glenoid bone loss

Restoration of native glenohumeral joint line is important for a successful outcome after reverse shoulder arthroplasty (RSA). The aims of this study were to quantify the restoration of glenoid joint line after structural bone grafting and RSA, and to evaluate graft incorporation, correction of glenoid version, and rate of notching. This is a retrospective review of 21 patients who underwent RSA (20 primary, 1 revision) with glenoid bone grafting (15 autografts, 6 allografts). Grammont design implants and baseplate with long peg were used in all patients. Preoperative and postoperative 3D models were created using MIMICS 21.0. Preoperative defects were classified, and postoperative joint line restoration was assessed based on the lateral aspect of the base of the coracoid. Postoperative computed tomographic (CT) scans were evaluated for graft incorporation, version correction, and presence of notching. Preoperative glenoid defects were classified as massive (5%), large (29%), moderate (52%), and small (14%). The average preoperative version was 8° of retroversion. The average postoperative version was 5° of retroversion. The average preoperative medialization was noted to be 8.4 mm medial to native joint line or 0.6 mm (range -16.8 to 13.2) lateral to the coracoid base. The postoperative CT scans demonstrated a mean joint line at 12.1 mm (range 1.3-22.4) lateral to the coracoid base. At the 3-month follow-up, all patients demonstrated graft incorporation on CT scans. Graft osteolysis was observed on CT scan in 4.8% of patients at a mean follow-up of 19.5 months. Structural bone grafting of glenoid defect effectively re-creates the glenoid anatomy, restores glenoid bone stock, re-creates the true glenohumeral joint line, and corrects glenoid deformity. The use of bone grafting also allows lateralization of the baseplate and glenosphere, reducing the risk of severe scapular notching. Restoration of the glenoid joint line was achieved in all patients. Glenoid bone grafting is a viable option for restoring glenoid joint line in cases of significant glenoid defects encountered during RSA.

A Postoperative Evaluation Guideline for Computer-Assisted Reconstruction of the Mandible

Valid comparisons of postoperative accuracy results in computer-assisted reconstruction of the mandible are difficult due to heterogeneity in imaging modalities, mandibular defect classification, and evaluation methodologies between studies. This guideline uses a step-by-step approach guiding the process of imaging, classification of mandibular defects and volume assessment of three-dimensional (3D) models, after which a legitimized quantitative accuracy evaluation method can be performed between the postoperative clinical situation and the preoperative virtual plan. The condyles and the vertical and horizontal corners of the mandible are used as bony landmarks to define virtual lines in the computer-assisted surgery (CAS) software. Between these lines the axial, coronal, and both sagittal mandibular angles are calculated on both pre- and postoperative 3D models of the (neo)mandible and subsequently the deviations are calculated. By superimposing the postoperative 3D model to the preoperative virtually planned 3D model, which is fixed to the XYZ axis, the deviation between pre- and postoperative virtually planned dental implant positions can be calculated. This protocol continues and specifies an earlier publication of this evaluation guideline.

Accuracy between virtual surgical planning and actual outcomes in orthognathic surgery by iterative closest point algorithm and color maps: A retrospective cohort study.

BackgroundTo evaluate the accuracy between actual outcomes and virtual surgical planning (VSP) in orthognathic surgery regarding the use of three-dimensional (3D) surface models for registration using iterative closest point (ICP) algorithm and generated color maps.Material and MethodsConstruction of planning and postoperative 3D models in STL files format (M0 and M1, respectively) from CBCT of 25 subjects who had been submitted to bimaxillary orthognathic surgery was performed. M0 and M1 were sent to Geomagic software in semi-automatic alignment surface mesh order of M0 and M1 for registration using ICP algorithm to calculate mean deviation (MD, MD+, MD-, SD) and root mean square (RMS – 3D Error). Color maps were generated to assess qualitative congruence between M0 and M1. From deviation analysis, 3D Error was defined as accuracy measurement. To assess the reproducibility, the workflow was performed by two evaluators multiple times. t-tests were used to assess whether all means of MD, MD+, MD-, SD and 3D Error values would be ≤ - 2 mm and ≥ 2 mm.ResultsHigh intra and inter evaluators correlation were found, supporting the reproducibility of the workflow. t-tests proved that all MDs and 3D Error values were > - 2 mm and < 2 mm.Conclusions3D error mean was within the standards of clinical success lower than 2 mm. ICP algorithm provided a reproducible method of alignment between 3D models and generated color maps to evaluate 3D congruence but did not answer all methodological parameters regarding the assessment of accuracy in orthognathic surgery. Key words:Accuracy, Cone-Beam computed tomography, CAD-CAM, Orthognathic surgery, three-dimensional imaging.

3D Modeling of Lower Extremities With Biplanar Radiographs: Reliability of Measures on Subsequent Examinations.

Biplanar radiography with 3-dimensional (3D) modeling (EOS) provides a comprehensive assessment of lower limb alignment in an upright weight-bearing position with less radiation than conventional radiography. A study was performed to assess the consistency and reliability of 2 lower extremity 3D biplanar radiograph models created at least 1 year apart in a pediatric population. All patients who had 2 lower extremity radiographic evaluations with EOS performed at visits a minimum of 1 year apart were reviewed. Digital radiographs, of lower extremities in both frontal and sagittal planes, were acquired simultaneously, using the EOS system. The 3D reconstruction of the images was achieved utilizing the SterEOS software. Pelvic position, femoral and tibial anatomy, and the torsional profile were evaluated and compared using t tests. In total, 53 patients with a mean age of 11.7 years (range, 6.1 to 18.9 y) met inclusion criteria. When comparing 3D models between visits, minimal differences were noted in proximal femoral anatomy and pelvic alignment (pelvic incidence, sacral slope, sagittal tilt, neck shaft angle). Expected differences in femoral and tibial length corresponded with normal longitudinal growth between visits. Sagittal plane knee position varied widely between examinations. Femoral and/or tibial rotational osteotomies were performed in 37% of extremities between examinations. After femoral derotational osteotomy, a significant difference in femoral anteversion was appreciated when comparing preoperative and postoperative 3D models. However, this difference was less than the expected difference based on the anatomic correction achieved intraoperatively. No differences were noted in tibial torsion measures after tibial derotational osteotomy. The 3D modeling based on biplanar radiographs provides consistent and reliable measures of pelvic and hip joint anatomy of the lower extremity. Patient positioning may influence the reproducibility of knee alignment. The torsional profile assessment did not accurately reflect changes obtained by derotational osteotomy. Level III.

Three-dimensional relationships between secondary changes and selective osteotomy parameters for biplane medial open-wedge high tibial osteotomy

BackgroundTo assess the axial rotational change of distal tibia and posterior tibial slope (PTS) change after OWHTO in 3-D planes and to identify the causal relationship on the effect of variation in the posterior slope angle and rotational errors. MethodsA total of 21 patients (23 knees) underwent OWHTO and were evaluated with 3D-CT before and after surgery. Medial proximal tibial angle in the coronal plane, PTS in the sagittal plane, and rotational axis in axial plane were evaluated and compared between pre- and post-operative 3D models constructed by applying reverse-engineering software. As a selective osteotomy parameter, hinge axis and gap ratio were measured in the postoperative 3D models ResultsThe increasing tendency of internal rotation of the distal tibia after OWHTO was positively related to hinge axis (β=0.730, p=0.001, R2=0.546) and gap ratio (β=−0.283, p=0.001, R2=0.520), which also showed statistically significant linear correlations to PTS changes after multivariate regression analysis that controlled for the rotational change of the distal tibia (hinge axis: β=0.443, p=0.006; gap ratio: β=0.144, p=0.017). ConclusionHinge axis more posterolaterally was related to a greater increase in internal rotation after biplane medial open-wedge HTO, and hinge axis and gap ratio were significant predictors of PTS change after rotational change was controlled for. Hinge axis has to be considered an important independent variable for limiting unintended axial rotation change as well as PTS change as secondary. Clinical relevanceThe relationship of the hinge axis with the rotational change and its influence to PTS change, acknowledged from by-product of the statistical analysis, might provide a deeper understanding of HTO, and should have constitutional effects on the development of HTO procedures and implants.

HEMODYNAMICS-BASED LONG-TERM PATENCY OF DIFFERENT SEQUENTIAL GRAFTING: A PATIENT-SPECIFIC MULTI-SCALE STUDY

Background and aims: Sequential grafting is one of the common coronary artery bypass grafting (CABG) surgery. But the influence of the sequential grafting position on hemodynamics and the graft patency is still unclear. Materials and methods: The zero-dimensional/three-dimensional (0D/3D) coupling method was used to finalize the multi-scale simulation of two different sequential grafting models. First, a patient-specific 3D model was reconstructed based on coronary computed tomography angiography (CCTA) images. Two different sequential grafts were implemented on this patient-specific 3D model by using virtual surgery. Thus, two different postoperative 3D models were built. Then, a lumped parameter model (LPM; 0D) was built based on the patient physiological data to simulate the cardiovascular system. Finally, the 0D/3D coupling method was used to perform the numerical simulation by coupling a 0D LPM of the cardiovascular system and the patient-specific 3D models. Moreover, the long-term patency of these two different sequential grafts was discussed in this paper. Results: The coronary flow rate and the graft flow were calculated and illustrated. The instantaneous wave-free ratio (iFR) were calculated. Postoperative iFR values increase to over 0.90 for both sequential grafts. Some hemodynamics parameters were also illustrated, such as wall shear stress (WSS), oscillatory shear index (OSI). The area of low WSS in Model 1 was much less than that in Model 2. Two regions of high OSI exist in Model 2, while only one in Model 1. Conclusions: No significant differences exist on the short-term outcomes of two models. But the long-term patency of Model 2 was worse. The Model 1 may enhance long-term patency of grafting and should be priority when the sequential grafting need to be carried out.

3D-Printing in Congenital Cardiology: From Flatland to Spaceland.

Medical imaging has changed to a great extent over the past few decades. It has been revolutionized by three-dimensional (3D) imaging techniques. Despite much of modern medicine relying on 3D imaging, which can be obtained accurately, we keep on being limited by visualization of the 3D content on two-dimensional flat screens. 3D-printing of graspable models could become a feasible technique to overcome this gap. Therefore, we printed pre- and postoperative 3D-models of a complex congenital heart defect. With this example, we intend to illustrate that these models hold value in preoperative planning, postoperative evaluation of a complex procedure, communication with the patient, and education of trainees. At this moment, 3D printing only leaves a small footprint, but makes already a big impression in the domain of cardiology and cardiovascular surgery. Further studies including more patients and more validated applications are needed to streamline 3D printing in the clinical setting of daily practice.

Three-dimensional in vivo difference between native acetabular version and acetabular component version influences iliopsoas impingement after total hip arthroplasty.

The potential influence of acetabular component orientation on iliopsoas impingement in total hip arthroplasty (THA) has not been previously quantified. The aim of the present study was to utilize pre- and post-operative CT-based 3D models to quantify iliopsoas impingement on acetabular components, and to identify any potential factors associated with iliopsoas impingement. Iliopsoas muscle was modelled from pre-operative CT scans and transferred to the post-operative 3D models in 19 THAs. The volume and the area of the overlap between iliopsoas muscle and acetabular cup (iliopsoas volume & area) was measured on axial and sagittal images. Most protruded lengths of cup uncovered by acetabular bone were measured on axial sagittal scan of CT scans. Version of acetabulum, acetabular cup, and the difference between the two (version difference) were also measured with cup inclination and size. Linear regression analysis was performed to identify any factor influencing iliopsoas impingement. Iliopsoas impingement volume and area were 100.6 ± 226.1 (range, 0.0-663.9) mm³ and 52.6 ± 102.0 (0.0-342.3) mm³, respectively. The protruded lengths on axial and sagittal view were 6.9 ± 5.3 (0.0-16.0) and 2.1 ± 2.7 (0.0-8.0). Linear regression model showed that version difference was significantly related to the iliopsoas impingement volume and area (beta = -0.709, p = 0.041 for volume, and beta = -0.684, p = 0.047 for area). The results of this study demonstrate that iliopsoas impingement on acetabular components was influenced by the version difference between pre-operative acetabular bone and acetabular component rather than the magnitude of post-operative cup version alone.