Patient-specific Plates Research Articles

A Pilot Study Evaluating the Accuracy of Patient Specific Custom Plates in Orthognathic Surgery

A Pilot Study Evaluating the Accuracy of Patient Specific Custom Plates in Orthognathic Surgery

The use of patient-specific implants in genioplasty and its clinical accuracy: a preliminary study

The purpose of this study was to assess the accuracy and clinical validation of patient-specific implants (PSI) in genioplasty. Fifteen patients with chin deformities were enrolled. Virtual planning was performed with the computer-aided surgical simulation method. The three-dimensional-printed titanium cutting guide and patient-specific plate were designed to guide the osteotomy and allow repositioning and fixation of the chin. The outcome was evaluated by comparing the plan with actual outcomes. All operations were successfully completed with PSIs. There was no difficulty in using patient-specific plates. The largest root-mean-square difference of the chin position was 0.69 mm in mediolateral translation and 2.01° in the yaw orientation. The results of the study indicated that the PSI technique was an accurate method of transferring the virtual plan to the operation field with great efficiency in genioplasty. A significant advantage of the PSI technique is that the patient-specific plate could simultaneously complete the repositioning and fixation of the chin. Intraoperative measurements and reposition guides were no longer required. Operative procedures were greatly simplified.

A rapid prototyping-based methodology for patient-specific contouring of osteotomy plates

PurposeAn important challenge of the osteotomy procedures, particularly in the case of large and complex corrections, is the fixation of the osteotomy site. The purpose of this study is to propose a practical and cost-effect methodology for the plate adapting problem of osteotomy surgery.Design/methodology/approachA novel patient-specific plate contouring methodology, based on rapid prototyping (RP) and multi-point forming (MPF) techniques, was developed and evaluated. In this methodology, a female mold is fabricated by RP, based on the geometry of the osteotomy site and estimation of the plate spring back. The mold is then used to configure a MPF die, which is then used for press forming of the factory-made locking plate. The applicability of the methodology was assessed in two case studies.FindingsThe results of implementing the methodology on a femoral and a tibial locking plate indicated very good conformity with the underlying bone, in both the frontal and sagittal planes. The surgical application of the pre-operatively contoured tibial plate facilitated the plate locating and screw inserting procedures, and provided a secure fixation for bone fragments.Practical implicationsThe results are promising and provide a proof of concept for the feasibility and applicability of the proposed methodology in clinical practice, as a complementary to the existing surgical preplanning and patient-specific instrument preparations.Originality/valueThe advantageous features of RP and the MPF were used to provide a solution for the plate adapting problem of osteotomy surgery.

3D printed patient-specific titanium plate versus conventional plate in head and neck reconstruction: a comparative study

3D printed patient-specific titanium plate versus conventional plate in head and neck reconstruction: a comparative study

Surgical Treatment for Posterior Dislocation of Hip Combined with Acetabular Fractures Using Preoperative Virtual Simulation and Three-Dimensional Printing Model-Assisted Precontoured Plate Fixation Techniques.

Background and Purpose Hip dislocation combined with acetabular fracture remains a challenging condition for orthopedic surgeons. In this study, we utilized a computer-assisted simulation and three-dimensional (3D) printing technology to treat patients with hip dislocation combined with acetabular fracture. We hypothesized that the 3D printing-assisted method would shorten the internal fixation time and surgical time. Methods We retrospectively reviewed 16 patients diagnosed with traumatic posterior dislocation of hip combined with acetabular fractures and treated with plate fixation from September 2013 to August 2017. Patients were divided into two groups: (1) traditional method and (2) 3D printing groups. In the traditional method group, the plates were contoured during the surgery, whereas in the 3D printing group, the patient's pelvic computed tomography image was transformed to the 3D medical image software for processing preoperatively. The fracture reduction was simulated by the computer. Thereafter, the 1:1 scale 3D printing model was used to design the surgical plan and contour patient-specific plates preoperatively. Results The internal fixation time was significantly shorter in the 3D printing group than in the traditional method group (-33 min, P<0.05). The mean operative time was shorter than that in the traditional method group (-43 min). However, blood loss and postoperative radiograph results were similar between the groups. The complication rate was lower in the 3D printing group (2/7) than in the traditional method group (5/9). Interpretation Computer-assisted simulation with 3D printing technology is a more efficient method for treating hip dislocation combined with acetabular fractures.

Complication rates and clinical outcomes of osseous free flaps: a retrospective comparison of CAD/CAM versus conventional fixation in 128 patients

Studies evaluating plate-related complications in patient-specific versus conventional fixation systems in free flap surgery are lacking. This was a retrospective study of 128 osseous free flaps with a minimum follow-up of 12 months. Wound healing disorders, plate exposure, fixation failure, and subtotal osseous union were recorded and evaluated statistically by univariate and regression analysis. Complication rates were as follows: wound healing disorders 33.6% (computer-aided design and computer-aided manufacturing (CAD/CAM) vs. conventional: 35.1% vs. 33.0%); plate exposure 21.9% (29.7% vs. 18.7%); fixation failure 7.0% (8.1% vs. 6.6%); subtotal osseous union 36.7% (45.9% vs. 33.0%). Radiotherapy (P<0.001) and more than two segments (P=0.026) were independent variables for the overall complication rate and were negatively correlated with the dental implantation rate. The time between diagnosis and ablative surgery was increased by 11.0days in the CAD/CAM group (34.2±16.2days vs. 23.2±12.0 days; P=0.002). Rates of dental rehabilitation were not significantly different (35.1% vs. 44.0%, P=0.358). On average, 3.2±1.7 dental implants were placed into flap segments. Plate-related complications were increased with radiotherapy and multisegment flaps. There was a non-significant trend towards increased complications with patient-specific plates in comparison to conventional reconstruction plates.

Patient specific glass fiber reinforced composite versus titanium plate: A comparative biomechanical analysis under cyclic dynamic loading

ObjectivesFree flap fixation with patient specific titanium (TI) plates is commonly performed after oncologic mandible resection, but plate exposure, osseous nonunion and imaging artefacts are associated complications. The aim of this study was to analyze interfragmentary movements and fatigue behaviour of patient specific titanium plates in comparison to a novel glass fiber reinforced composite (GFRC) plate in vitro. MethodsTwo polyurethane fibula segments were fixed to a corresponding mandible (Synbone AG, Malans, CH) with a patient specific 2.0 mm titanium plate (DePuy Synthes, Umkirch, Germany and Materialise, Leuven, Belgium) or one of two patient specific GFRC plates with different glass fiber orientation. Plate fixation to the fibula segments was performed with monocortical non-locking screws in all groups. Plate fixation to the mandible was performed with bicortical locking screws in the titanium group and with bicortical non-locking screws in the GFRC groups. Mastication was simulated via cyclic dynamic loading on the left side at a rate of 1 Hz with increasing peak loading (+0.15 N/cycle, Bionix, MTS, Eden Prairie, USA). A three-dimensional optical measuring system (PONTOS 5 M, GOM, Braunschweig, Germany) was used to determine interfragmentary movements between mandible and fibula segments. ResultsMean plate stiffness of GFRC plates was 431 ± 64 N/mm and 453 ± 70 N/mm versus 560 ± 112 N/mm in the titanium group. No significant differences were found for the number of loading cycles until a vertical displacement of 1.0 mm (p = 0.637) and for vertical displacement over time (p = 0.490). Interosteotomy gap movement differed significantly between titanium and GFRC plates in the right distal (p = 0.001), intermediate (p = 0.006) and left distal gap (p = 0.025). ConclusionsCAD/CAM titanium plates with locking screws provide increased stiffness and reduced interosteotomy movements in comparison to CAD/CAM glass fiber reinforced composite plates with non-locking titanium screws. Future studies should evaluate the influence of mechanobiologically optimized fixation systems on bone healing in free flap surgery.

TOWARDS PATIENT SPECIFIC PLATE IMPLANTS FOR THE HUMAN LONG BONES: A DISTAL HUMERUS EXAMPLE

Plate implants are the most used internal fixators for the surgical treatments of the bone fractures. In clinical cases where there is a requirement to use reconstruction plates, and/or to stabilize the fracture, adaptation of plate shape (e.g. bending) to the patient anatomy is required, and it is usually done during the surgery. In order to eliminate the need for intra-operative bending of plates, precontoured plates can be used. These are patient specific implants whose shape and geometry is adapted to the anatomy and morphology of the specific patient. In order to create a patient specific 3D model of the plate implant, the bone model acquired through medical imaging (e.g. Computed Tomography - CT) is commonly used. By the application of various CAD techniques, the volume model of specific plate implant can be created, and used for the production of the plate, by conventional or additive manufacturing technologies. In this paper the authors present a new approach to the creation of a 3D parametric model of the patient specific plate implant for distal humerus. By using such model the surgeon can perform preoperative planning and adapt shape of plate to the specific patient before the surgery, and in this way he can improve pre, intra and post-operative processes.

Patient-Specific Printed Plates Improve Surgical Accuracy In Vitro

It remains unclear to what extent patient-specific printed plates can improve surgical outcomes in orthognathic procedures. This study aimed to quantify the surgical accuracy of patient-specific printed plates invitro and to compare the results with patients' actual surgical outcomes. This invitro study enrolled 20 postoperative orthognathic surgical patients, all treated with inferior maxillary repositioning. The preoperative midfaces were re-created in a 3-dimensionally printed model. The osteotomy and screw holes were placed at prespecified positions using a 3-dimensional guide. The dental segment was repositioned by means of the patient-specific plates. The primary outcome was the mean reposition at 3 dental reference points. The primary predictor variable was the obtained surgical reposition invitro compared with the virtual surgical plan. Confounding variables were gender, age, occlusion, and bimaxillary surgery. The secondary outcome was surgical accuracy, and the secondary predictor was the invitro outcomes versus the patients' surgical outcomes. Surgical accuracy was defined as the difference between the obtained reposition and the virtual surgical plan on a continuous scale. The differences were recorded in 3 dimensions according to the positive valueof the 3 axes: right, anterior, and posterior. The results were analyzed using mixed-model regression and 1-sample t tests. In the 20 patients (age, 18 to 64years; 40% of patients were women), the mean planned reposition was 2.9mm anterior and 1.8mm inferior. In all models, the osteotomy edge was rounded off to position the plate in the predetermined position. Overall, the maxilla was positioned 0.5mm anterior and 0.3mm inferior to the planned position using patient-specific plates. The patient-specific plates positioned the maxilla in close approximation to the planned position without surgically relevant differences. The osteotomy edge must be carefully inspected for interference with the patient-specific plates to avoid displacement of the planned maxillary repositioning.

Parametric design of patient-specific fixation plates for distal femur fractures.

To facilitate the creation, modification, and optimization of patient-specific plates for distal femur fractures, a novel approach was proposed for the rapid and convenient design of patient-specific plates for patients' fractured femurs using feature parameterization. First, several femur parameter values were obtained for a specific patient and used to construct a restored surface model of the fractured femur. Next, combined with the particular femur anatomy and the fracture, a parameterized plate with a suitable shape was created automatically based on the parameter maps between the femur and plate. Finally, using finite-element analysis, the Von Mises stresses of the plate under human gait loads were calculated to evaluate the biomechanical performance of the plate, and the plate was optimized for specific patients by recursively adjusting the parameter values. Case results indicate that patient-specific plate models can be created rapidly based on the fractured femur modes of patients and can be optimized efficiently with high-level semantic parameters. Therefore, the proposed approach may be used as a basic tool for the design and modification of patient-specific plates for use in orthopedic operations.

3D printing in designing of anatomical posterior column plate

BackgroundAcetabulum has a complex anatomy due to which anatomical acetabular plates are still under developmental phase. Although intra-operative contouring of reconstruction plate is done as a standard practice, it is associated with increased operative time and morbidity of patient. We have designed an acetabular plate for posterior fixation from experience of previous studies performed in our institute on acetabular fracture fixation which should be appropriate for most of the patient of Indian origin. Apart from avoiding intra-operative contouring of acetabular plates it also helps in preventing intra articular screw penetration. MethodsWe selected five consecutive patients with acetabular fracture needed to be operated from posterior approach and designed patient specific plate template from virtual surgical planning and 3D printing. These plate templates were then matched with our acetabular plate design and were used intra-operatively. Many parameters were assessed to evaluate accuracy of our plate design in those five patients. ResultAll the plate templates appear to match our designed plate and no intra-operative contouring was required with our plate design. ConclusionThis was a pilot study and we need a large sample size to study accuracy of our acetabular plate design which might avoid intra-operative contouring, decreasing morbidity of patient and prevent wastage of resources in pre-operative planning and computer designing.

Surgical Accuracy in Inferior Maxillary Reposition

Inferior maxillary repositioning is among the least stable and least predictable orthognathic procedures. The purpose of this study was to investigate whether posterior movement occurred with inferior maxillary repositioning and to analyze potential causes. This retrospective observational study evaluated all consecutive patients treated at the Department of Oral and Maxillofacial Surgery of the Odense University Hospital (Odense, Denmark) with inferior maxillary repositioning from 2011 to 2013. The obtained repositioning was compared with the virtual surgical plan to determine surgical accuracy. Measurements were performed at 3 dental reference points. Linear and rotational measurements were performed along and around the right, anterior, and superior axes. Measurements were compared by paired t tests. Internal correlations and confounding variables were analyzed by mixed model regression analysis. Twenty patients were included for analysis. On average, the maxilla was positioned 1mm posterior and 0.4mm superior to the planned position. The virtual surgically planned reposition was statistically correlated with surgical accuracy. No other confounding variable influenced the outcome. The correlation between planned advancement and inferior repositioning suggests that inferior repositioning destabilizes the maxillary position and that a perioperative or early postoperative relapse occurs in response to the advancement. This immediate relapse of 1mm should be considered in the virtual surgical plan to ensure that the maxilla is placed closer to the desired position. Thus, this procedure could still benefit from increased surgical precision and stability based on technologic advancements, such as positioning guides or printed patient-specific plates.

The Use of Pre-Milled Plates in Mandibular Reconstruction: A Case Series of Seven Patients

Restoration of segmental resection of the posterior mandible remains a challenge for oral and maxillofacial surgeons. Patients often require reconstruction with plates and screw retention to provide continuity and strength, followed by bone grafting. Several factors are required for reconstruction of the mandible including the correct contour, maxillomandibular occlusal relationship, and repositioning of the condyle to restore adequate function [1]. Mandibular reconstruction with vascularized flaps may be considered the gold standard by some [2] though in many cases, the use of free flaps is contraindicated, such as when the patient is deemed unsuitable for a prolonged operative procedure or when microvascular expertise is unavailable [3]. For patients who have not received a vascularized flap, a secondary surgery for bone grafting was traditionally necessary to bridge the defect [4]. The use of mandibular reconstruction plates without subsequent bone grafting has resulted in plate fractures in approximately 2.9% to 10.7% of patients [5]. Plate fractures usually occur within 2 years of resection, but most occur within 6 months of the operation. A recent study of pre-milled mandibular reconstruction plates in 71 patients showed that there were no cases of plate fracture after an average 11.8-month follow-up [6]. By using virtual model planning to create custom pre-milled patient specific mandibular plates (PSMP), the requirements for future plates can be met, and may provide the advantage of avoiding secondary bone grafting.

Computer-assisted versus traditional freehand technique in fibular free flap mandibular reconstruction: a morphological comparative study.

The purpose of the study was to compare the accuracy of computer-assisted surgery (CAS) and the traditional freehand technique for fibular free flap mandibular reconstruction as well as to evaluate the accuracy of the CAS planning. The medical records of 18 patients who underwent mandibular reconstruction with fibular free flap were reviewed. The CAS group (n=7) benefited from virtual surgical planning and custom patient-specific plates and surgical cutting guides. The Control group (n=11) was treated by conventional surgery. Morphometric comparison was done by calculating the differences in specific linear and angular parameters on pre- and postoperative CT-scans for both groups by using ProPlan CMF® software. Symmetry was also assessed by calculating the ratio of the affected versus the nonaffected side. In the CAS group, planned and postoperative CT-scans were compared to evaluate accuracy. The morphometric comparison showed no statistically significant differences between the groups except for the axial angle on the nonaffected side (mean difference 1.0° in the CAS group versus 2.9° in the Control group; p=0.03). Ratios of the affected side over the nonaffected side showed no differences between the two groups. In the CAS group, the accuracy assessment showed a mean distance deviation of 2.3mm for mandibular osteotomies and 1.9mm for fibular osteotomies. Our results indicated that CAS and the conventional freehand techniques were comparable in their ability to provide a satisfactory morphological fibular free flap mandibular reconstruction. Moreover, the accuracy of the CAS technique was within the range reported in the literature.

A parametric approach to construct femur models and their fixation plates

ABSTRACTAlthough anatomic plates reflect an important breakthrough in the treatment of distal femur fractures, there are still some patients experiencing healing complications. For individual differences in bone morphology and fractures, the development of patient specific plates is very complex and needs a long cycle. In this study, a parametric approach was proposed to conveniently construct femur models and design their fixation plates. First, the typical femur anatomy was described with the average femur model. Second, five surface features were defined to represent the femur surface model by setting up parameterization and parameter constraints. Third, according to the fracture information of a specific patient, customized plate surface with a suitable contour was created from the reconstructed femur model. Finally, the femur plate was represented by feature parameterization, and the hierarchical constraints between femur parameters and plate parameters were built to construct a plate model. The experimental results showed that the proposed method could effectively represent femur surface shape features and intuitively construct and edit individualized plates with high-level parameters. The method is competitive in time saving and design convenience and may provide a basic tool for digital restoration of incomplete femurs and the design of patient specific femur plates.

The accuracy of patient specific osteosynthesis plate allows immediate placement of dental implants in mandibular reconstruction with free fibular flaps

The accuracy of patient specific osteosynthesis plate allows immediate placement of dental implants in mandibular reconstruction with free fibular flaps

Evaluation of accuracy of patient specific precontoured plates in acetabular fracture fixation

Evaluation of accuracy of patient specific precontoured plates in acetabular fracture fixation

Patient-specific distal radius locking plate for fixation and accurate 3D positioning in corrective osteotomy.

Preoperative three-dimensional planning methods have been described extensively. However, transferring the virtual plan to the patient is often challenging. In this report, we describe the management of a severely malunited distal radius fracture using a patient-specific plate for accurate spatial positioning and fixation. Twenty months postoperatively the patient shows almost painless reconstruction and a nearly normal range of motion.