3D-printed Prosthesis Research Articles

Comparative study of Lutetium-177 and Phosphorus-32 in radioactive bone cement for the treatment of vertebral body metastasis.

Vertebroplasty is a minimally invasive outpatient procedure to stabilize compression fractures in the spine. This procedure involves injecting bone cement into the vertebrae that have been cracked or broken, typically due to osteoporosis. The cement hardens inside the bones, providing stability to the fractures and supporting the spine. Additionally, radioactive bone cement and brachytherapy sources have been utilized to suppress tumor growth in the vertebral body. We present a novel brachytherapy technique for treating vertebral body metastases using a liquid form of radioactive sources, Phosphorus-32 and Lutetium-177, separately mixed with bone cement and injected into vertebral body bone prostheses. We also investigated the dose distribution of the radioactive bone cement by theoretically calculating it using GEANT4 Monte Carlo and measuring it using TLD dosimeters for Phosphorus-32 and Lutetium-177 loaded in vertebral bodies. CT-scanned images of each vertebral body (L2 and L3) were imported into GEANT4 for simulation purposes. Two simulations were performed to evaluate the possibility of using PLA prostheses in ex vivo measurements, using bone and PLA material as a bone substitute for brachytherapy of Lutetium-177 and Phosphorus-32. The simulations calculated the dose distribution, dose rates, and deposited dose to the spinal cord and aorta. Next, 3D-printed bone prostheses were drilled and separately filled with bone cement, including PMMA-P32 and PMMA-Lu177, in liquid form using the Vertebroplasty technique. The dose to regions of interest was measured using Thermoluminescence dosimeters. When comparing the simulated and measured results of dose rates, it was observed that P32 delivers higher doses to normal organs such as the spinal cord and aorta. At the same time, Lu177 has better sparing in these regions of interest. Therefore, while P32 and Lu177 are suitable for radioactive bone cement treatment, Lu177 delivers relatively lower doses to vital organs such as the spinal cord and aorta. Additionally, Lu177 has characteristics such as a shorter range and lower energies of beta particles in tissue and the presence of gamma rays that make it a better choice for the same treatments. It also provides the possibility of SPECT imaging.

A novel three-dimensional-printed patient-specific sacral implant for spinopelvic reconstruction in sacral giant cell tumour.

Spinopelvic reconstruction after sacral tumour resection is one of the most demanding procedures in sacral tumour surgery. The aims of this study were to evaluate the feasibility of spinopelvic reconstruction with 3D-printed prostheses in sacral giant cell tumours and the clinical outcomes and complications at follow-up. We retrospectively analyzed ten consecutive patients with giant cell tumors of the sacrum who underwent intralesional nerve-sparing resection with curative intent and custom implant reconstruction between 2016 and 2021. There were four males and six females with a mean age of 40.2years (range, 25-62years) at surgery. A computer-aided-design implant was prepared using 3D printing technology that was both matched to the bone defect and biomechanically evaluated. A 3D-printed surgical guide was used to replicate the resection procedure as planned. We analyzed operational outcomes, oncological outcomes, functional outcomes, complications, and prosthetic outcomes. Pain at rest was assessed according to a 10-cm VAS score. The results of functional improvement were evaluated using the MSTS-93 score at the final follow-up. All patients were observed for 26 to 61months, with an average follow-up of 43.8months. No deep infection or prosthetic structural failure occurred in this study. A total of 80% of patients had good neurological function and normal urinary, bowel, and ambulatory functions. The mean MSTS score was 24.1 (range, 22-26). The mean VAS score was 2 (range 0 to 2). Delayed wound healing occurred in three patients, and the wounds healed after debridement. One case had local recurrence and survived tumour-free after resection of the recurrent lesion. An aseptic loosening was found in a patient that did not require secondary surgery. By radiographical assessments, we found that 90% of implants were well osseointegrated at the final follow-up examination. The 3D-printed sacral implants might provide a promising strategy for spinopelvic reconstruction in sacral giant cell tumours undergoing intralesional nerve-sparing surgery with satisfactory clinical outcomes, osseointegration, and excellent durability.

Sternal Reconstruction Using 3D-Printed Titanium Custom-Made Prosthesis for Sternal Dehiscence After Cardiac Surgery.

Sternal dehiscence is an important complication that increases mortality and morbidity in cardiac surgery. Titanium plates have been used to reconstruct the chest wall for a long time. However, with the rise of 3D printing technology, a more sophisticated method, is making a breakthrough. Custom-made 3D-printed titanium prostheses are increasingly used in chest wall reconstruction because they allow almost perfect fitting to the patient's chest wall and lead to good functional and cosmetic results. This report presents a complex anterior chest wall reconstruction using a custom-made titanium 3D-printed implant in a patient with a sternal dehiscence after coronary artery bypass surgery. At first, reconstruction of the sternum was performed using conventional methods, which failed to give adequate results. Finally, a 3D-printed titanium custom-made prosthesis was used for the first time in our center. On the short- and mid-term follow up, good functional results were achieved. In conclusion, this method is suitable for sternal reconstruction after complications in the healing process of median sternotomy wounds in cardiac surgery, especially where other methods do not provide satisfactory results.

3D-printed custom ossicular prosthesis - methodology of design and LDV measurements in a cadaver study.

In tympanoplasty, surgical reconstruction of the tympanic membrane and ossicular chain is well-established; however, its hearing results still require improvement. Custom 3D printing of individualized ossicular prostheses seems to be an attractive solution for optimal prosthesis adjustment and better hearing results. The aim was to design a custom ossicular prosthesis using a 3D printing method based on Cone-beam Computed Tomography (CBCT) scans and assess the acoustic conduction properties of such prosthesis. A cadaver fresh frozen temporal bone was used. Based on CBCT images, a new incus prosthesis was designed and 3D printed. Next, canal wall-up tympanoplasty was performed. The intact ossicular chain and reconstructed 3D-printed prosthesis chain movements/vibrations were measured with Laser Doppler Vibrometer (LDV) system and analyzed in detail. The CBCT scans provided enough information about the anatomical structures. For frequencies 500 and 1000 Hz and 80 dB SPL sound intensity, collected velocities were higher for the intact ossicular chain than the 3D-printed ossicular prosthesis. The intensity thresholds for movement at 500 and 1000 Hz were lower in the intact ossicular chain than in the 3D-printed ossicular prosthesis. At 2000 Hz, there was the same intensity threshold value in the two measured circumstances. It is possible to design a custom individually fitted ossicular prosthesis using a 3D printing method based on CBCT scans. The acoustic conduction properties of such 3D-printed prosthesis showed differences in movability pattern between the intact and reconstructed ossicular chain. More data are needed to analyze the acoustic properties of such designed prostheses in detail. The results of our experiment showed the 3D-printed prosthesis presents the potential to be an interesting option for conductive hearing loss treatment caused by chronic otitis media and the ossicular chain defects.

The use of titanium custom-made 3D-printed prosthesis with reconstruction of scapholunate interosseous ligament in the treatment of scaphoid nonunion

article: The use of titanium custom-made 3D-printed prosthesis with reconstruction of scapholunate interosseous ligament in the treatment of scaphoid nonunion - Minerva Orthopedics 2023 February;74(1):14-9 - Minerva Medica - Journals

A classification system of joint-salvage tumor resection in osteosarcoma of the knee: A retrospective cohort study

BackgroundJoint-preserving surgery is possible for patients with juxta-articular osteosarcoma of the knee, even when the tumor invades the epiphysis. Oncologic and functional outcomes may vary due to the extent of tumor invasion, the amount of epiphysis preservation, and reconstruction methods. We aimed to introduce a novel classification facilitating clinical evaluation of different surgical treatments. MethodsWe identified 52 patients with osteosarcoma of the knee undergoing joint-preserving tumor resection and intercalary reconstruction. We classified procedures into two types and six subtypes based on the tumor location and adjuvant treatment employed. Oncologic outcomes, limb function and complications were compared among different types. ResultsNone of the patients had a local recurrence in the preserved epiphysis apart from three (5.7 %) who had local recurrence in soft tissue. Overall survival rate of the patients was 82.7 % at 5 and 10 years. There was no difference in survival rate (P = 0.909), local recurrence (P = 0.642) between type I (tumor not invading epiphysis) and type II (tumor invading epiphysis). In addition to one skin necrosis in the 3D-printed prosthesis reconstruction and one infection in Capanna reconstruction, all complications necessitating additional surgery occurred in allograft. The Musculoskeletal Tumor Society (MSTS) scores ranged from 21 to 30 with a median of 26. There were differences in the MSTS scores among six subgroups (P = 0.015), with the highest in type Ia and the lowest in type IIc. The less of the viable epiphysis retained, the worse the knee function was at long-term follow up. ConclusionsThe suggested classification can guide surgical strategy and is convenient for comparison of the functional results.

Reconstruction of massive bone defects after femoral tumor resection using two new-designed 3D-printed intercalary prostheses: a clinical analytic study with the cooperative utilization of multiple technologies

BackgroundTo reconstruct massive bone defects of the femoral diaphysis and proximal end with limited bilateral cortical bone after joint-preserving musculoskeletal tumor resections, two novel 3D-printed customized intercalary femoral prostheses were applied.MethodsA series of nine patients with malignancies who received these novel 3D-printed prostheses were retrospectively studied between July 2018 and November 2021. The proximal and diaphyseal femur was divided into three regions of interest (ROIs) according to anatomic landmarks, and anatomic measurements were conducted on 50 computed tomography images showing normal femurs. Based on the individual implant-involved ROIs, osteotomy level, and anatomical and biomechanical features, two alternative 3D-printed prostheses were designed. In each patient, Hounsfield Unit (HU) value thresholding and finite element analysis were conducted to identify the bone trabecula and calcar femorale and to determine the stress distribution, respectively. We described the characteristics of each prosthesis and surgical procedure and recorded the intraoperative data. All patients underwent regular postoperative follow-up, in which the clinical, functional and radiographical outcomes were evaluated.ResultsWith the ROI division and radiographic measurements, insufficient bilateral cortical bones for anchoring the traditional stem were verified in the normal proximal femur. Therefore, two 3D-printed intercalary endoprostheses, a Type A prosthesis with a proximal curved stem and a Type B prosthesis with a proximal anchorage-slot and corresponding locking screws, were designed. Based on HU value thresholding and finite element analysis, the 3D-printed proximal stems in all prostheses maximally preserved the trabecular bone and calcar femorale and optimized the biomechanical distribution, as did the proximal screws. With the 3D-printed osteotomy guide plates and reaming guide plates, all patients underwent the operation uneventfully with a satisfactory duration (325.00 ± 62.60 min) and bleeding volume (922.22 ± 222.36 ml). In the follow-up, Harris Hip and Musculoskeletal Tumor Society scores were ameliorated after surgery (P < 0.001 and P < 0.001, respectively), reliable bone ingrowth was observed, and no major complications occurred.ConclusionsTwo novel 3D-printed femoral intercalary prostheses, which achieved acceptable overall postoperative outcomes, were used as appropriate alternatives for oncologic patients with massive bone defects and limited residual bone and increased the opportunities for joint‐preserving tumor resection. Several scientific methodologies utilized in this study may promote the clinical design proposals of 3D-printed implants.

Fit analysis of stereolithography-manufactured three-unit resin prosthesis with different 3D-printing build orientations and layer thicknesses

Statement of problemPrinting conditions can affect the fit of a 3-dimensionally (3D) printed prosthesis. Therefore, it is important to determine the optimal printing conditions for stereolithography (SLA)-manufactured prostheses. PurposeThe purpose of this study was to analyze the fit according to the build orientations and layer thicknesses in SLA-manufactured 3-unit resin prostheses. Material and methodsSLA 3D printed prostheses were produced in 5 build orientations (0, 30, 45, 60, and 90 degrees) and 2 layer thicknesses (50 and 100 μm). Milled prostheses were fabricated from the same design. The mounted prostheses on the master model were scanned with microcomputed tomography (μCT). Data were processed with the NRecon software program. For quantitative analysis, marginal and internal fits were measured by using the imageJ software program in terms of the following metrics: absolute marginal discrepancy, marginal gap, cervical area, midaxial wall area, line-angle area, and occlusal area. Internal gap volume was also measured with the CTAn software program. For statistical analysis, ANOVA and Tukey HSD tests were used (α=.05). For qualitative analysis, μCT cross-sections were compared among groups, and intaglio surfaces were imaged with a scanning electron microscope. ResultsA layer thickness of 50 μm with build orientations of 45 and 60 degrees exhibited smaller mean gap values (P<.05) than the other conditions for all measurements except line-angle area and occlusal area. The scanning electron microscope images showed voids on the intaglio surfaces for the 0- and 90-degree groups. ConclusionsFor SLA 3D printed resin prostheses, a difference in fit occurred based on the printing conditions, although both 3D printed and milled prostheses showed a clinically acceptable fit. When an SLA 3D printed prosthesis is manufactured under appropriate conditions, a clinically acceptable fit can be obtained.

A Planned Multidisciplinary Surgical Approach to Treat Primary Pelvic Malignancies.

The pelvic anatomy poses great challenges to orthopedic surgeons. Sarcomas are often large in size and typically enclosed in the narrow confines of the pelvis with the close proximity of vital structures. The aim of this study is to report a systematic planned multidisciplinary surgical approach to treat pelvic sarcomas. Seventeen patients affected by bone and soft tissue sarcomas of the pelvis, treated using a planned multidisciplinary surgical approach, combining the expertise of orthopedic oncology and other surgeons (colleagues from urology, vascular surgery, abdominal surgery, gynecology and plastic surgery), were included. Seven patients were treated with hindquarter amputation; 10 patients underwent excision of the tumor. Reconstruction of bone defects was conducted in six patients with a custom-made 3D-printed pelvic prosthesis. Thirteen patients experienced at least one complication. Well-organized multidisciplinary collaborations between each subspecialty are the cornerstone for the management of patients affected by pelvic sarcomas, which should be conducted in specialized centers. A multidisciplinary surgical approach is of paramount importance in order to obtain the best successful surgical results and adequate margins for achieving acceptable outcomes.

Reconstruction with 3D-printed prostheses after type I + II + III internal hemipelvectomy: Finite element analysis and preliminary outcomes.

Background: Prosthetic reconstruction after type I + II+ III internal hemipelvectomy remains challenging due to the lack of osseointegration and presence of giant shear force at the sacroiliac joint. The purpose of this study was to evaluate the biomechanical properties of the novel 3D-printed, custom-made prosthesis with pedicle screw-rod system and sacral tray using finite element analysis. Methods: Four models that included one intact pelvis were established for validation. Forces of 500N and 2,000N were applied, respectively, to simulate static bipedal standing and the most loaded condition during a gait cycle. Biomechanical analysis was performed, and the results were compared; the preliminary outcomes of four patients were recorded. Results: For the reconstructed hemipelvis, stress was mainly concentrated on the sacral screws, bone-prosthesis interface, and upper endplate of the L5 vertebra. The optimization of the design with the sacral tray structure could decrease the peak stress of the sacral screws by 18.6%, while the maximal stress of the prosthesis increased by 60.7%. The addition of the lumbosacral pedicle-rod system further alleviated stress of the sacral screws and prosthesis by 30.2% and 19.4%, respectively. The site of peak stress was contemporaneously transferred to the connecting rods within an elastic range. In the retrospective clinical study, four patients who had undergone prosthetic reconstruction were included. During a follow-up of 16.6 ± 7.5months, the walking ability was found preserved in all patients who are still alive and no prosthesis-related complications had occurred except for one hip dislocation. The Musculoskeletal Tumor Society (MSTS) score was found to be 19.5 ± 2.9. Conclusion: The novel reconstructive system yielded favorable biomechanical characteristics and demonstrated promising preliminary outcomes. The method can be used as a reference for reconstruction after type I + II + III hemipelvectomy.

Design and Production of Low-Cost 3D-Printed Transtibial Prosthetic Sockets

ABSTRACT Introduction Only 5% to 15% of individuals with amputation living in low- and middle-income countries (LMICs) have access to proper prostheses. Mainly, prosthetic costs are too high, and facilities are not within reach. Measurement and production of traditional prosthetic sockets are time-consuming, labor-intensive, and highly dependent on the experience and skills of the personnel involved. Materials and Methods This report describes the workflow to produce low-cost patella tendon bearing transtibial prosthetic sockets. Using computer-aided design (CAD) and computer-aided manufacturing (CAM), transtibial prostheses can be easily produced in rural areas. The size of the residual limb was scanned with a handheld 3D-scanner (Einscanner Pro Plus), and the sockets were printed using fused filament fabrication (FFF) with an Ultimaker S5. The foot was made locally, and the other prosthetic parts were imported. The 3D-printed socket costs US $20 (excluding value-added tax [VAT]). The total material cost of the prosthesis, including the other prosthetic materials, amounts to approximately US $100 (excluding VAT). Assuming the asset cost of the devices, the costs of one local employee, overhead expenses, a profit margin, and the VAT included, a 3D-printed prosthesis could be sold for US $170. Conclusions This report provides a blueprint to produce low-cost 3D-printed transtibial prosthetic sockets. Further research will be conducted to replace the imported prosthetic parts for local products and to automatize the digital design process. Clinical Relevance With this workflow, prosthetic sockets can be produced consistently, which makes it a suitable method in LMICs.

A Personalized 3D-Printed Hand Prosthesis for Early Intervention in Children With Congenital Below-Elbow Deficiency: User-Centered Design Case Study

The adoption of prosthetic hands by children with congenital upper limb deficiency from a very early age has benefits in terms of reducing prosthesis abandonment, improving body image, and mitigating developmental and physiological complications that arise from the underuse of the deficit arm. However, current hand prostheses present drawbacks that make them not suitable for very young children. This study investigates the design requirements of a prosthesis for very young children with congenital below-elbow deficiency using a user-centered design (UCD) approach. The UCD puts the child at the center of the design process, with parents as mediators between the child and the design team. The study was conducted with an interdisciplinary team over three years, with several prototypes developed for different growth stages of the child. This paper presents the adopted UCD approach and its timeline, the iterative prototypes of the prosthesis developed throughout the study, and the final prototype with a focus on its child-friendly features. Finally, the paper describes the design requirements concluded from the study and the authors’ recommendations for implementing prosthetic hands in below-elbow early intervention.

Is 3D-printed prosthesis stable and economic enough for anterior spinal column reconstruction after spinal tumor resection? A retrospective comparative study between 3D-printed off-the-shelf prosthesis and titanium mesh cage.

To investigate the stability and cost-effectiveness of the three-dimensional-printed (3DP) off-the-shelf (OTS) prosthesis in the reconstruction of the anterior column of the thoracic/lumbar spine after tumor resection. Thirty-five patients (26 with primary malignant tumors and nine with metastatic malignant tumors) who underwent tumor resection and anterior column reconstruction between January 2014 and January 2019 were included in a single institute. Patients were divided into the 3DP OTS prosthesis (3DP) group (n = 14) and the titanium mesh cage (TMC) group (n = 21) by the type of implant. The operation time, intraoperative blood loss, hospital stay, history of radiotherapy, surgical level and total cost were collected and compared between the two groups. Mechanical complications and radiological parameters including mean vertebral height, subsidence, fixation failure(nonunion, migration, screw loosening, rod breakage) rate were recorded at preoperation, 1week, 3months, 6months, 12months after surgery then at 1year interval or stop until the end of survival. The follow-up patients were also sent with short form-36 to assess their health-related quality of life (HRQoL) and questions about the current condition of their disease. The mean overall follow-up was 24.6months. Of the 35 patients involved, six patients died and six were lost to follow-up. The differences between the two groups in operative time, intraoperative blood loss, and hospital stay were not statistically significant (p > 0.05). The differences in fixation failure and the subsidence rate between the two groups were not statistical significant (p > 0.05). The difference of subsidence rate between the cases with and without osteoporosis, cases with and without radiotherapy was statistically significant within each group (p < 0.05). However, the difference of subsidence rate between the surgical level above or below T10 was not statistically significant (p > 0.05). The response rate of the questionnaire among the survived patients was 100% (23/23 patients). The results of the Short Form- (SF-)36 between the two groups were similar (p > 0.05). The total cost was higher in the 3DP group (p < 0.05) with its higher graft cost (p < 0.05), but the differences in internal fixation cost and other cost were not statistically significant between groups (p > 0.05). Compared to TMC, the 3DP OTS prosthesis achieved similar clinical and radiological results in spinal anterior spinal column reconstruction of thoracic/lumbar spinal tumor resection. However, the 3DP OTS prosthesis was more expansive than TMC.

The clinical application of customized 3D-printed porous tantalum scaffolds combined with Masquelet’s induced membrane technique to reconstruct infective segmental femoral defect

PurposeThis study mainly exams a novel treatment for infective segmental femoral defect, and we combined the 3D printed porous tantalum prosthesis and Masquelet’s induce membrane technique to reconstruct bone defect and discussed the clinical effect.MethodThe clinical research included 9 observational cases series, as a permanently implantation, the customized 3D-printed scaffolds that connected with an anatomical plate was implanted into the bone defect segment after successful formation of induced membrane, the clinical effect was evaluated by radiological exams and Paley’s bone union criteria.ResultThe personalized 3D-printed porous tantalum was, respectively, manufactured and used in 9 consecutive patients to reconstruct the infective segmental bone defect of femur, the mean defect length was 16.1 ± 2.8 cm, the mean length of follow-up was 16.9 ± 4.0 months, after 2 stage operation, there was no deep infections, refractures, sensorimotor disorder, vascular injury, ankylosis and recurrence of infection occurred in all cases. postoperative radiological exams shown stable internal fixation and osseointegration, and all these results were invariable during the follow-up time in all cases. All patients significantly obtained deformity correction and length of limb.ConclusionThe customized 3D-printed porous tantalum prosthesis was an acceptable alternative treatment to the autogenous or allograft bone graft, the combination of the two techniques could achieve satisfactory reconstruct to infective broad bone defect in femur when other biological techniques were not suitable.

Biomechanical comparison of different prosthetic reconstructions in total en bloc spondylectomy: a finite element study

ObjectiveTo analyse and compare the biomechanical differences between 3D-printed prostheses, titanium mesh cages and poorly matched titanium mesh cages in total en bloc spondylectomy (TES).MethodsThe finite element model of T10-L2 for healthy adults was modified to make three models after T12 total spondylectomy. These models were a 3D-printed prosthesis, titanium mesh cage and prosthesis-endplate mismatched titanium mesh cage for reconstruction. The range of motion (ROM), stress distribution of the endplate and internal fixation system of three models in flexion and extension, lateral bending and axial rotation were simulated and analysed by ABAQUS.ResultIn flexion, due to the support of the anterior prosthesis, the fixation system showed the maximum fixation strength. The fixation strength of the 3D-printed prosthesis model was 26.73 N·m /°, that of the TMC support model was 27.20 N·m /°, and that of the poorly matched TMC model was 24.16 N·m /°. In flexion, the L1 upper endplate stress of the poorly matched TMC model was 35.5% and 49.6% higher than that of the TMC and 3D-printed prosthesis, respectively. It was 17% and 28.1% higher in extension, 39.3% and 42.5% higher in lateral bending, and 82.9% and 91.2% higher in axial rotation, respectively. The lower endplate of T11 showed a similar trend, but the magnitude of the stress change was reduced. In the stress analysis of the 3D-printed prosthesis and TMC, it was found that the maximum stress was in flexion and axial rotation, followed by left and right bending, and the least stress was in extension. However, the mismatched TMC withstood the maximum von Mises stress of 418.7 MPa (almost twice as much as the buckling state) in rotation, 3 times and 5.83 times in extension, and 1.29 and 2.85 times in lateral bending, respectively.ConclusionDifferent prostheses with good endplate matching after total spondylectomy can obtain effective postoperative stable support, and the reduction in contact area caused by mismatch will affect the biomechanical properties and increase the probability of internal fixation failure.

Influence of lifestyle pattern on preference for prosthetic hands: Understanding the development pathway for 3D-printed prostheses

Assistive technologies have been recognized as a particularly powerful aid for increasing the independence and social integration of the people with disabilities in an aging society, where the extent of acquired disability is significant. For the development of novel assistive technologies to be effective, it is necessary to properly understand the needs of consumers. Therefore, this study identifies the heterogeneous preference of potential users of 3D-printed prosthetic hands with regards to their daily lifestyle patterns using discrete choice experiment and latent class analysis. The results indicate that the consumers of prosthetic hands have varying group-wise preferences for different types of prosthetics based on their lifestyle patterns. Specifically, those who spend more time at home were less concerned about weight and dexterity than those who were younger and spent more time outside at work and leisure. In all, the development of 3D-printed prosthetic hands needs to be directed towards reducing weight and increasing functionality for further adoption. Our findings will enhance the understanding of assistive technologies adoption and provide important strategic implications by suggesting the required progress and development pathway of 3D-printed prosthetic hands to increase market penetration and satisfy unmet needs.

Comparison of customized 3D-printed prosthesis and screw-rod-cage system reconstruction following resection of periacetabular tumors.

Background and purposeVarious operative methods are used for reconstructing pelvic girdle after resection of primary malignant periacetabular tumor has been reported. The objective of this study was to evaluate the accuracy, effectiveness, and safety of customized three dimensional-printed prosthesis (3DP) in the reconstruction of bone defects compared with conventional reconstruction using the screw-rod-cage system.MethodsA retrospective case–control analysis of 40 patients who underwent pelvic tumor resection and reconstruction with a customized 3D-printed prosthesis (3DP), or screw-rod-cage system (SRCS) between January 2010 and December 2019 was performed. The minimum follow-up time for patients alive was 2 years. Blood loss, operation time, complications, surgical margin, local recurrence, distant metastases, status at time of latest follow-up, MSTS-93 score, Harris hip score, and postoperative radiographic parameters were recorded. Moreover, overall survival, tumor-free survival, and prosthesis survival rates in both groups were compared.ResultsCustomized 3DP reconstruction was performed in 15 patients, and SRCS reconstruction was done in 25 patients. The group of patients treated with customized 3DP reconstruction had significantly shorter operation time (323.7 ± 83.7 vs. 393.6 ± 98.8 min; P = 0.028) and more precise (all P < 0.05) radiographic reconstruction parameters than patients in the SRCS group. Fewer complications (P = 0.026), better MSTS score (P = 0.030), and better Harris hip score (P = 0.016) were achieved in the 3DP group. Furthermore, the survival rate of prosthesis was also significantly better in the 3DP group (P = 0.039). However, blood loss, surgical margin, local recurrence, distant metastases, and status at time of latest follow-up had no significant difference between two groups.ConclusionCompared with the screw-rod-cage system reconstruction, the customized 3D-printed prosthesis reconstruction is equally safe and effective, but it is more accurate and time-saving and is associated with fewer complications.

3D-printed hemipelvic prosthesis combined with a dual mobility bearing in patients with primary malignant neoplasm involving the acetabulum: clinical outcomes and finite element analysis

BackgroundLimb salvage reconstruction for pelvic tumors, especially periacetabular tumors, is challenging. We combined the use of dual mobility bearing and 3D-printed hemipelvic prosthesis to improve function and reduce the probability of complications after hemi-pelvic resection in patients with primary acetabular malignancy. The purpose of this study was to evaluate the efficacy and safety of this combination.MethodsBetween October 2011 and May 2021, 11 patients with malignancies involving the acetabulum received hemipelvic replacement with a 3D-printed prosthesis and dual mobility bearing. Follow‐up of postoperative survival, complications, and Musculoskeletal Tumor Society 93 (MSTS-93) lower limb functional scores were carried out. A finite element model of the postoperative pelvis was developed and input into the finite element analysis software. The Von Mises equivalent stress formula was used to analyze the stress distribution of each part of the pelvis under one gait cycle and the stress distribution at different angles of the hip joint.ResultsBy the last follow-up, 9 of the 11 patients (81.8%) were still alive, and 2 patients had local tumor recurrence. The complications including 1 deep infection and 1 dislocation of the artificial joint. Excluding 1 amputation patient, the average score of the remaining 8 patients at the last follow-up was 21.4/30 (71.3%) on the MSTS-93. In the reconstructed pelvis, stress distributions were concentrated on the junction between hemipelvic prosthesis and screw and iliac bone on the resected side, and between femoral prosthesis stem and femoral bulb, while the stress of polyethylene lining was small. Before impact, the polyethylene lining will rotate at a small angle, about 3°. The inner stress of polyethylene liner is greater than the outer stress in all conditions. The polyethylene liner has no tendency to slide out.ConclusionPelvic tumor resection and reconstruction using 3D-printed hemipelvic prosthesis combined with dual mobility bearing was an effective treatment for pelvic tumors. Our patients achieved good early postoperative efficacy and functional recovery. The dual mobility bearing is beneficial to prevent dislocation, and the mechanical distribution and wear of the prosthesis are acceptable.

Comparative analysis of intaglio surface trueness of cement-retained implant-supported prostheses generated by a cast-free digital workflow and a three-dimensionally printed cast workflow

Statement of problemComparative analysis of the accuracy of the prostheses produced by a cast-free digital workflow and 3-dimensional (3D) printing cast workflow is lacking. PurposeThe purpose of the present investigation was to compare the intaglio surface trueness of implant-supported prostheses fabricated by using 3 different digital workflows: cast-free computer-aided design (CAD), 3D printed cast CAD (direct insert), and 3D printed cast CAD (indirect insert). Material and methodsThe laboratory data of 11 partially edentulous arches for prosthetic implant treatment were obtained. Three different workflows were tested to produce the cement-retained prostheses: cast-free CAD (Group CF), 3D printed cast CAD with direct insert (Group PD), and 3D printed cast CAD with indirect insert (Group PI). The intaglio surfaces of the prosthesis CAD data from Groups CF, PD, and PI were superimposed with 3D printed prosthesis scan data from Group CF to measure 3D surface deviation. Using the prosthesis CAD data from Group CF as a reference, those from Groups PD and PI were compared by superimposition analysis. The root mean square (RMS) estimates, positive average deviations, and negative average deviations were measured. The Kruskal-Wallis test and Dunn test with Bonferroni correction, and the Wilcoxon rank sum test were used for statistical analyses (α=.05). ResultsSignificant differences were found among the 3 groups when the 3D printed prosthesis scan data were referenced (P<.05). Group CF showed the lowest RMS, positive average deviation, and negative deviation values, while Group PI showed the highest values. Significant differences in the RMS, positive average deviation, and negative average deviation values were found between Groups PD and PI when the prosthesis CAD data (Group CF) were referenced (P<.05). ConclusionsAmong the 3 different workflows tested, the prostheses generated from the cast-free CAD flow showed significantly lower intaglio surface deviation than those generated from the 3D printed cast CAD flows, regardless of the insertion method of the implant replicas.

Customized three dimensional printed prosthesis as a novel intercalary reconstruction for resection of extremity bone tumours: a retrospective cohort study.

The 3D-printed prosthesis (3DP) is a novel treatment for massive bone defect reconstruction after tumor resection. This study was aiming to explore the clinical efficacy of customized 3DP for intercalary reconstruction by comparing the clinical outcomes after implanting customized 3DP or conventional allograft in limb salvage surgery. A total of 28 patients with extremity bone tumors who underwent customized 3DP or conventional allograft reconstruction between 2011 and 2018 at our institution were analyzed retrospectively. Among them, 14 cases received customized 3DP reconstruction (3DP group), and 14 cases received conventional allograft reconstruction (control group). Demographics, surgical outcomes, radiographical assessments, limb functions, and post-operative complications between these two groups were collected to evaluate clinical outcomes. No significant difference was observed in the demographics, mean intra-operative blood loss, MOSI scores, and MSTS scores between the two groups. Patients in 3DP group had a shorter operative time (157.9 vs 199.6min, p = 0.03) and lesser number of fluoroscopy (4.1 vs 8.1, p < 0.001) compared to control group. The mean time to osseointegration at bone-implant interfaces in 3DP group was significantly earlier than that in control group (6.1 vs 12.2months, p < 0.001). Moreover, the 3DP group had a significantly lower post-operative complication rate than the control group (7% vs 50%, p = 0.03). The customized 3DP might provide a promising strategy for intercalary reconstruction in limb salvage surgery with more precise reconstruction, higher surgical efficiency, and comparable satisfactory clinical outcomes.