Use Of Patient-specific Implants Research Articles

3D maxillofacial surgery planning - one decade development of technology.

Nowadays, techniques and the use of patient specific implants seem to be the recent high technology standard in reconstructive surgery. Surgery planning is as old as the surgery procedures themselves. Any good surgeon, before entering the operating theatre, has a plan for how to proceed. It is based on knowledge and experience in combination of evaluation of all case relevant information. In fact, virtual surgery planning and CAD/CAM reflects the technological "state of the art" into the medical daily practice. Recently, 3D printing technologies became easy and accessible for everyone. Virtual 3D images substituted the plaster models, the film profile analysis switched to digital, 3D printed bone models of the case helped to understand the morphology of the deformity and prepare the osteotomies with "hands on the bone". The authors' own 20 years of experience on surgical planning, the development of digital technologies in oral and maxillofacial surgery is traced and comments on case examples are presented.

The Utility of 3D Printing for Surgical Planning and Patient-Specific Implant Design in Maxillofacial Surgery: A Narrative Review.

Maxillofacial reconstructive implants are typically created in standard shapes and have a widespread application in head and neck surgery. During surgical procedures, the implant must be correctly bent according to the architecture of the particular bones. Bending takes practice, especially for untrained surgeons. Furthermore, repeated bending may increase internal stress, resulting in fatigue in vivo under masticatory loading and an array of consequences, including implant failure. There is a risk of fracture, screw loosening, and bone resorption. Resorption, infection, and displacement are usually associated with the use of premade alloplastic implants and autogenous grafts. Recent technological breakthroughs have led to the use of patient-specific implants (PSIs) developed by computer-designed additive manufacturing in reconstructive surgery. The use of computer-designed three-dimensional (3D)-printedPSI allows for more precise restoration of maxillofacial deformities, avoiding the common difficulties associated with premade implants and increasing patient satisfaction. Additive manufacturing is something that refers to a group of additive manufacturing methods. This technique has been quickly used in a variety of surgical procedures. The exponential expansion of this technology can be attributed to its enormous surgical value. Adding 3D printing to a medical practice can be a rewarding experience with stunning results.

The Use of Patient-Specific Implants for the Treatment of Upper Extremity Fractures.

In this article, we discuss the use of three-dimensional (3-D) printed patient-specific implants in the management of upper extremity fractures. Traditional fracture fixation methods involve the use of standard-sized implants, which may not adequately address the needs of every patient, particularly those who have complications related to fracture nonunion or malunion and those who have significant bone loss. The benefits and limitations of this technology are also discussed, along with considerations for implementation in clinical practice. Overall, the use of 3-D printed patient-specific implants holds promise for improving the accuracy and efficacy of upper extremity fracture management.

Clinical Stability of Bespoke Snowman Plates for Fixation following Sagittal Split Ramus Osteotomy of the Mandible.

Maxillofacial skeletal surgery often involves the use of patient-specific implants. However, errors in obtaining patient data and designing and manufacturing patient-specific plates and guides can occur even with accurate virtual surgery. To address these errors, bespoke Snowman plates were designed to allow movement of the mandible. This study aimed to compare the stability of bespoke four-hole miniplates with that of a bespoke Snowman plate for bilateral sagittal split ramus osteotomy (SSRO), and to present a method to investigate joint cavity changes, as well as superimpose virtual and actual surgical images of the mandible. This retrospective study included 22 patients who met the inclusion criteria and underwent orthognathic surgery at a university hospital between 2015 and 2018. Two groups were formed on the basis of the plates used: a control group with four-hole bespoke plates and a study group with bespoke Snowman plates. Stability was assessed by measuring the condyle-fossa space and superimposing three-dimensional virtual surgery images on postoperative cone-beam computed tomography (CBCT) scans. No significant differences were observed in the condyle-fossa space preoperatively and 1 year postoperatively between the control and study groups. Superimposing virtual surgery and CBCT scans revealed minimal differences in the landmark points, with no variation between groups or timepoints. The use of bespoke Snowman plates for stabilizing the mandible following SSRO exhibited clinical stability and reliability similar to those with bespoke four-hole plates. Additionally, a novel method was introduced to evaluate skeletal stability by separately analyzing the condyle-fossa gap changes and assessing the mandibular position.

Robot-assisted implantation of additively manufactured patient-specific orthopaedic implants: evaluation in a sheep model.

Bone tumours must be surgically excised in one piece with a margin of healthy tissue. The unique nature of each bone tumour case is well suited to the use of patient-specific implants, with additive manufacturing allowing production of highly complex geometries. This work represents the first assessment of the combination of surgical robotics and patient-specific additively manufactured implants. The development and evaluation of a robotic system for bone tumour excision, capable of milling complex osteotomy paths, is described. The developed system was evaluated as part of an animal trial on 24 adult male sheep, in which robotic bone excision of the distal femur was followed by placement of patient-specific implants with operative time evaluated. Assessment of implant placement accuracy was completed based on post-operative CT scans. A mean overall implant position error of 1.05 ± 0.53mm was achieved, in combination with a mean orientation error of 2.38 ± 0.98°. A mean procedure time (from access to implantation, excluding opening and closing) of 89.3 ± 25.25min was observed, with recorded surgical time between 58 and 133min, with this approximately evenly divided between robotic (43.9 ± 15.32) and implant-based (45.4 ± 18.97) tasks. This work demonstrates the ability for robotics to achieve repeatable and precise removal of complex bone volumes of the type that would allow en bloc removal of a bone tumour. These robotically created volumes can be precisely filled with additively manufactured patient-specific implants, with minimal gap between cut surface and implant interface.

194. The use of Modified patient-specific implant design for treatment of delayed zygomaticomaxillary and orbital floor fracture – A case report and literature review

The repair of delayed zygomaticomaxillary and orbital floor fractures are surgically challenging due to bony malunion, loss of normal anatomical landmarks and tethered scar tissue. Functional disturbances occur not only due to soft tissue entrapment and scar related tethering but alteration in bony volume and position resulting in hypoglobus and enophthalmos. The use of patient-specific implants (PSI) has been gaining popularity to improve the accuracy of orbital reconstruction. We present a modification in our ORBITAL PSI design to avoid extensive zygomatic osteotomies while still accurately reconstructing the orbit.

Accuracy of mandibular anterior subapical osteotomy by virtual planning in orthognathic surgery using patient-specific implants

IntroductionMandibular anterior subapical osteotomy (MASO) is a complementary procedure during orthognathic surgery to correct proclination or extrusion of the anterior incisors when orthodontic movements fail. The increasing use of patient-specific implants (PSI, titanium plates) in orthognathic surgery has extended to this procedure. Digital orthognathic surgery planning involves manufacturing cutting/drilling guides and specific implants to provide better accuracy and allow complex movement with reduced surgical times compared to conventional planning. This study aimed to assess the accuracy of computer-aided surgery with patient-specific implants in mobilising the MASO segment according to planning. MethodsEleven consecutive patients with mean age 26.82 years (15–41, SD = 10.65) were treated with MASO in addition to other conventional orthognathic procedures incorporating digital planning and patient-specific implants. A three-dimensional “stl” format file of the mandibular dental arch was obtained using an intraoral scanner at the end of the surgical procedure. The accuracy of the MASO segment displacement imposed by PSI was assessed by comparing preoperative 3D-planned mandibular dental arch with the immediate postoperative 3D-measured arch, using surface superimposition and 7 standard dental landmarks. Deviations between the preoperative and postoperative landmarks were calculated and compared to determine whether MASO segment repositioning is sufficiently accurate to be safely used to reposition the incisor/canine axis. ResultsQuantitative analysis revealed an absolute linear difference of 0.66 mm (SD = 0.51) between preoperative 3D digital dental arch impression and postoperative planned 3D dental arch. Overall, the median absolute discrepancies in the x-axis (right-left direction), y-axis (antero-posterior direction), and z-axis (supero-inferior direction) were respectively 0.56 mm (SD = 0.42), 0.77 mm (SD = 0.45) and 0.65 mm (SD = 0.61). ConclusionA high degree of accuracy between the virtual plan and the immediate postoperative result was observed. According to our results, PSI can be used safely with accuracy in MASO as an adjunct to other conventional orthognathic procedures.

Prospective Evaluation of Two Wall Orbital Fractures Involving the Medial Orbital Wall: PSI Reconstruction versus PDS Repair-Worth the Effort?

Proper treatment of the two-wall fractured orbit is still controversial. Specifically, there is no consensus on the issue of the necessity of medial orbital wall repair. With anatomically critical structures at risk during the surgical approach, surgeons’ view on the necessity of medial orbital wall repair often is restricted and an aesthetically disturbing enophthalmos is more likely to be accepted. Therefore, treatment options range from leaving the medial wall without repair to reconstruction with autogenous tissue or alloplastic materials, which can lead to moderate to severe side effects. However, emerging technologies such as patient-specific implants (PSI) offer a reliable and anatomically correct reconstruction of the bony orbit. This study aimed to evaluate the outcome of full orbital reconstruction using PSIs compared to only orbital floor repair using PDS (bioresorbable polydioxanone) foils leaving the medial orbital wall untouched in traumatic two-wall orbital fractures. Of all patients treated at the University Hospital of Düsseldorf between 2017 and 2019 who suffered from traumatic orbital fracture, only patients with a two-wall orbital fracture involving both the orbital floor and the medial wall (n = 68) were included. Patients were treated either with a PSI (n = 35) or a PDS foil (n = 33). Primary outcome parameters were ophthalmological disturbances analyzed via clinical investigation and intra-orbital angles, volumes and implant position analyzed with radiological 3D-datasets. While a two-wall reconstruction using PSIs led to a significant improvement of the enophthalmos, the rate of postoperative enophthalmos was significantly increased in cases of only orbital floor repair with PDS foils. Radiologically, a significant reconstruction of the three-dimensional bony orbit succeeded with the simple use of PSIs leading to a significant reduction in the traumatically enlarged orbital volume. PSI also led to a significant reduction in the traumatically enlarged medial angle of the orbit. This was not the case for single-floor repair with PDS foil. The results of this study suggest that complex orbital fractures can be reconstructed at an even higher degree of accuracy with selective laser-melted PSIs than PDS foils. In order to achieve a true to original reconstruction of the bony orbit, surgical treatment of the medial orbital wall can be advocated for in the long term depending on the indication.

Patient-specific implants in orbital reconstruction.

Advances in the use of patient-specific implants (PSIs) and virtual surgical planning (VSP) for reconstruction of primary and secondary traumatic orbital defects are explored. PSIs and VSP are emerging technologies that promise to make complex orbital reconstructions safer and more predictable for patients. Recent studies highlight principles of implant design, the novel use of multiunit implant constructs, and utility of intraoperative imaging adjuncts to achieve favorable outcomes. This article summarizes recent developments in PSIs for orbital reconstruction. A complete workflow including presurgical planning, execution in the operating room, postoperative analysis, and avoidance of common pitfalls and implant design errors are reviewed.

Pitfalls of Surgeon-Engineer Communication and the Effect of In-House Engineer Training During Digital Planning of Patient-Specific Implants for Orbital Reconstruction

The use of patient-specific implants for reconstruction of complex orbital floor defects is increasing and requires communication with an industry partner, which warrants investigation. Therefore, the aim of this study was to evaluate the effects of in-house training of engineers on such communication as well as to identify frequent sources of problems and their solutions for improvement of the implant-planning workflow. We conducted a retrospective cross-sectional study and enrolled a sample of patients who had undergone orbital reconstruction with patient-specific implants between 2017 and 2020. The predictor variables were in-house training (additional training completed in hospital or not) and implant complexity (complex [multiwalled implants] vs less complex [isolated orbital floor reconstructions]). The outcome variables were duration of communication, message length, and need for synchronous communication or modifications to the original design. Descriptive, univariate, and multivariate statistics were computed, and statistical significance was set at a P value of < 0.05. This study included the data of 66 patients (48 men and 18 women, average age: 42.27years). The complexity of the implant statistically significantly increased the duration of the communication (8.76 vs 16.03days; P=.004). In 72.73%, the initial design had to be changed. Engineers trained in house required less communication to plan less-complex implants and generally needed fewer corrections to the original design (P=.020 and P=.036, respectively). Problems during planning were observed in 25.76% of the cases, with an insufficient diagnostic 3-dimensional data set being the most common (15.15%). In-house training of engineers is time-saving while planning the workflow for patient-specific implants, especially in less-complex cases, given that design changes are not needed often. The high rate of data sets that were insufficient for planning patient-specific implants suggests that diagnostic 3-dimensional data sets should already meet the requirements for such planning.

Peri- and postoperative complications in Le Fort I osteotomies

This retrospective study was performed to report the peri- and postoperative complications encountered by patients who underwent Le Fort I osteotomy, as well as predictor variables affecting the risk of complications.Patients who underwent only Le Fort I osteotomy were included in the study. Information on peri- and postoperative complications were collected from the patient data records. The effects of certain predictor variables on complication rates were also studied.Twenty-four per cent of the patients suffered from complications, six (6.1%) of whom were reoperated. Most of the complications were minor and transient. Compared with one-piece osteotomy, segmental osteotomy was a significant risk factor predisposing patients to postoperative complications (p = 0.04619). Additionally, the use of patient-specific implants seemed to increase the risk of both perioperative and postoperative complications (p = 0.0248).Currently, the conventional plate fixation method is the primary method in Le Fort I osteotomies. Careful patient selection, surgical planning, and selection of surgical technique seem to be the most important factors in reducing the complication risk. Special attention should be paid with segmental osteotomy surgery.

Patient-Specific Implants for Focal Cartilage Lesions in The Knee: Implant Survivorship Analysis up to Seven Years Post-Implantation

In the quest for increased surgical precision and improved joint kinematics, Computer-Assisted Orthopedic Surgery (CAOS) shows promising results for both total and partial joint replacement. In the knee, computer-assisted joint design can now be applied to the treatment of younger patients suffering pain and restriction of activity due to focal defects in their femoral articular cartilage. By taking MRI scans of the affected knee and digitally segmenting these scans, we can identify and map focal defects in cartilage and bone. Metallic implants matched to the defect can be fabricated, and guide instrumentation to ensure proper implant alignment and depth of recession in the surrounding cartilage can be designed from segmented MRI scans. Beginning in 2012, a series of 682 patient-specific implants were designed based on MRI analysis of femoral cartilage focal defects, and implanted in 612 knees. A Kaplan-Meier analysis found a cumulative survivorship of 96% at 7-year follow-up from the first implantation. Fourteen (2.3%) of these implants required revision due to disease progression, incorrect implant positioning, and inadequate lesion coverage at the time of surgery. These survivorship data compare favorably with all other modes of treatment for femoral focal cartilage lesions and support the use of patient-specific implants designed from segmented MRI scans in these cases.

Clinical Efficacy of Patient-specific Implants Manufactured using Direct Metal Laser Sintering (DMLS) Technology in Patients with Mandibular Defects

Purpose: The purpose of this study was to compare the clinical efficacy of patient-specific implants (PSIs) in patients with mandibular defects in the early and distant postoperative period. Materials and Methods: The surgical results in 60 patients with postoperative and posttraumatic mandibular discontinuous defects were analyzed. The patients were treated at the Center of Maxillofacial Surgery and Dentistry, Kyiv Regional Clinical Hospital in the period from 2015 to 2020. Results: Despite certain functional limitations and residual aesthetic deficiency, 34 patients (85%) of the main group and 9 (45 percent) of the control group noted an improvement in their quality of life and were satisfied with the results of the operation (р &lt; 0.05). Conclusions: The use of PSIs, compared to traditional methods of bone grafting, allow to achieve a more accurate restoration of the anatomical shape of the mandible in areas with complex geometry and probably better aesthetic results, and significantly reduces the frequency of secondary displacement of bone fragments due to plastic deformation and destruction of fixation elements (p &lt; 0.05). At the same time, it probably does not affect the frequency of purulent-inflammatory complications, unsatisfactory clinical results and the effectiveness of the restoration of masticatory function in patients with mandibular defects.

Implicit and explicit finite element models predict the mechanical response of calcium phosphate-titanium cranial implants

The structural integrity of cranial implants is of great clinical importance, as they aim to provide cerebral protection after neurosurgery or trauma. With the increased use of patient-specific implants, the mechanical response of each implant cannot be characterized experimentally in a practical way. However, computational models provide an excellent possibility for efficiently predicting the mechanical response of patient-specific implants. This study developed finite element models (FEMs) of titanium-reinforced calcium phosphate (CaP–Ti) implants. The models were validated with previously obtained experimental data for two different CaP–Ti implant designs (D1 and D2), in which generically shaped implant specimens were loaded in compression at either quasi-static (1 mm/min) or impact (5 kg, 1.52 m/s) loading rates.The FEMs showed agreement with experimental data in the force–displacement response for both implant designs. The implicit FEMs predicted the peak load with an underestimation for D1 (9%) and an overestimation for D2 (11%). Furthermore, the shape of the force–displacement curves were well predicted. In the explicit FEMs, the first part of the force–displacement response showed 5% difference for D1 and 2% difference for D2, with respect to the experimentally derived peak loads. The explicit FEMs efficiently predicted the maximum displacements with 1% and 4% difference for D1 and D2, respectively. Compared to the CaP–Ti implant, an average parietal cranial bone FEM showed a stiffer response, greater energy absorption and less deformation under the same impact conditions.The framework developed for modelling the CaP–Ti implants has a potential for modelling CaP materials in other composite implants in future studies since it only used literature based input and matched boundary conditions. Furthermore, the developed FEMs make an important contribution to future evaluations of patient-specific CaP–Ti cranial implant designs in various loading scenarios.

Management of Painful Shoulder Arthroplasty: A Narrative Review.

Despite the recent advances in surgical techniques, the percentage of painful shoulder arthroplasties is still high (more than 10%). The causes of residual pain after shoulder arthroplasty, and the resulting treatment solutions, are many and different. The most common complications of shoulder prosthesis are infections, aseptic loosening, modular components disassembling, metal hypersensitivity, and instability. There are also implant-related complications such as glenoid wear in hemiarthroplasty, rotator cuff tear in anatomical total shoulder arthroplasty, scapular notching, and acromion fracture in reverse shoulder arthroplasty. Several of these complications can be avoided with a careful selection of the implants, a proper surgical technique and a precise implant positioning. The execution of a more accurate preoperative planning and the possible use of patient-specific implants are expected to translate into better clinical results in the future. We provide the reader with recent evidence on the causes and therapeutic options of this condition.

Computer-Assisted Secondary Orbital Reconstruction.

This study presents a case-control study of 33 patients who underwent secondary orbital reconstruction, evaluating techniques and outcome. Adequate functional and aesthetical appearance are main goals for secondary orbital reconstruction. Insufficient premorbid orbital reconstruction can result in hypoglobus, enophthalmos, and diplopia. Computer-assisted surgery and the use of patient-specific implants (PSIs) is widely described in the literature. The authors evaluate the use of selective laser-melted PSIs and hypothesize that PSIs are an excellent option for secondary orbital reconstruction. The sample was composed of 33 patients, previously treated with primary orbital reconstruction, presenting themselves with indications for secondary reconstruction (i.e. enophthalmos, diplopia, or limited eye motility). Computed tomography and/or cone beam data sets were assessed before and after secondary reconstruction comparing intraorbital volumes, infraorbital angles, and clinical symptoms. Clinical outcomes were assessed using a standardized protocol. Results show a significant change in intraorbital volumes and a reduction of clinical symptoms after secondary reconstruction. Outcomes of this study suggest that secondary orbital reconstruction can be performed routinely using selective laser-melted PSIs and titanium spacers.

CAD/CAM Engineered Patient-Specific Impants as a Reposition Device in Le Fort I and Modified Subcondylar Osteotomies: Case Report of Facial Deformity Correction in Acromegaly.

Acromegaly is a medical condition where elevated growth hormone or insulin-like growth factor I levels cause several changes in the craniofacial soft and hard features. We report the correction of facial deformity and posterior open bite with Le Fort I and modified subcondylar osteotomies in a patient affected by acromegaly. Computer-aided design and manufacturing generated saw and drill guides were used to perform osteotomies and segment removal. The placement of the patient-specific implants (PSIs) was guided by predesigned drill holes ensuring the required and planned movement of the jaws and position of the PSIs. After segment removal, the PSIs fitted the predesigned drill holes with high precision and were secured without problems. The planned amount of mandibular and maxillary movement was achieved. The occlusion and osteotomies remained stable for the follow-up of 22 months. The use of PSIs combined with guided surgery can be beneficial for selected cases with asymmetry or posterior open bite enabling new approaches and yielding good functional and aesthetic outcome. The modification of conventional ramus osteotomy combined with utilization of ramus segment removal and the use of PSI for reposition is an interesting and promising technique for rare conditions with ramus height asymmetry.

Accuracy Assessment of Molded, Patient-Specific Polymethylmethacrylate Craniofacial Implants Compared to Their 3D Printed Originals.

The use of patient-specific implants (PSIs) in craniofacial surgery is often limited due to a lack of expertise and/or production costs. Therefore, a simple and cost-efficient template-based fabrication workflow has been developed to overcome these disadvantages. The aim of this study is to assess the accuracy of PSIs made from their original templates. For a representative cranial defect (CRD) and a temporo-orbital defect (TOD), ten PSIs were made from polymethylmethacrylate (PMMA) using computer-aided design (CAD) and three-dimensional (3D) printing technology. These customized implants were measured and compared with their original 3D printed templates. The implants for the CRD revealed a root mean square (RMS) value ranging from 1.128 to 0.469 mm with a median RMS (Q1 to Q3) of 0.574 (0.528 to 0.701) mm. Those for the TOD revealed an RMS value ranging from 1.079 to 0.630 mm with a median RMS (Q1 to Q3) of 0.843 (0.635 to 0.943) mm. This study demonstrates that a highly precise duplication of PSIs can be achieved using this template-molding workflow. Thus, virtually planned implants can be accurately transferred into haptic PSIs. This workflow appears to offer a sophisticated solution for craniofacial reconstruction and continues to prove itself in daily clinical practice.

The Use of Patient-Specific Implants in Oral and Maxillofacial Surgery.

This article summarizes the current use of patient-specific implants in oral and maxillofacial surgery.

S16-02 SESSION 16: PLANNING/IMAGING – PART II TRANSLATION OF PATIENT UNIQUENESS AND TREATMENT PLAN INTO PRE-SURGICAL PLANNING OF CRANIOPLASTY SURGERY USING WEB ACCESS 3D MODEL-BASED ICT TOOLS

Introduction: Although cranioplasty is considered to be a frequent and straightforward procedure, studies have shown complication rate up to 34%. While cranioplasty with autogenous bone is still regarded as the gold standard to restore cranial vault integrity, there is currently no consensus for the optimal material in the management of cranial defects. Emerging manufacturing technologies and the development of new materials offer an wide range of solutions, yet one can assume that material is chosen in regard of price, lead time, reimbursement policy and medical institutions’ preferences, but rarely according to the initial indication and the expected outcomes for such procedure, which prevent patient-specific devices from achieving large-scale utilization despite their demonstrated superiority over off-the-shelf solutions. It is therefore necessary to promote new approaches, via the development of innovative ICT tools, integrating clinical support during the pre-surgical planning, translating clinical history, treatment plan and follow-up strategy into the design of patient-specific cranial implants to achieve better clinical outcome. Methods: To transform this paradigm nowadays established in cranioplasty surgery, the first open access 3D virtual model-based ICT tools for surgeon-manufacturer communication and pre-surgical planning, serving as patient-specific implant configurator in regard of patient and pathology specificities, has been developed for the management of complex clinical cases. Results: This tool successfully grants the surgeons, via the manipulation of 3D models, the ability to describe in a more natural way, the individual solutions to realize for the treatment of a particular patient. Additionally, the surgeon’s participation in the co-creation and approval processes of the solution is being facilitated by the specification of requirements on virtual models and the systematization of the design features. Along with it, the accumulated experience of the use of patient-specific implants (PSI) is used as a clinical decision support and as a learning tool to create added value not only for patients, but for surgeons and medical institutions as well. Conclusion: This newly developed 3D virtual model-based technology, set as surgeon-manufacturer communication for PSI order and configurator, ensures correct data interpretation, product safety and functionality while taking into account the specificity of one patient for whom the device is prescribed. Those will accelerate the shift of the surgical thought paradigm towards personalized approach and undoubtedly will help achieve better clinical outcome, shorten delivery time and drop the costs of the implants used to manage rare and complex clinical cases.