Reconstruction with 3D-printed pelvic endoprostheses after resection of a pelvic tumour

3D Customized Biological Tibial Intramedullary Nail Fixation for the Treatment of Fracture after Massive Allograft Bone Transplantation of Tibial Osteosarcoma: A Case Report

Allograft bone fractures are critical complications in massive allograft bone transplantations. There are limited studies available on the application of 3D printing for massive allograft bone transplantation complications, and no related reports on the treatment of an allograft bone fracture with a complete biological intramedullary nail. A complex case of allograft bone fracture after massive bone transplantation for a right tibial osteosarcoma was treated with fixation of an individualized 3D printed biological tibial intramedullary nail. Prior to the operation, the intramedullary nail was designed and printed based on the results of computed tomography examination of the affected limb, and the surface of the intramedullary nail was treated with a hydroxyapatite coating. Intraoperatively, the intramedullary nail was implanted according to the preoperative 3D design plan. The intraoperative and postoperative examinations showed that the 3D printed intramedullary nail achieved good matching between the implant and the medullary cavity, and the biological coating integrated well with surrounding bone. The follow-up results 44 months postoperatively showed that the patient was satisfied with the surgical results, where his ankle function met his daily needs, and the Musculoskeletal Tumor Society score was 24. 3D printing tibial intramedullary nail fixation can be successful in the treatment of allograft bone fractures and should be considered as a treatment of choice. In this case, the intramedullary nail matched the surrounding bone well, had good osseointegration, and the patient regained basic function.

Pelvic Endoprosthesis after Hemipelvectomy Using a 3D-Printed Osteotomy Guide for Infiltrative Osteoma in a Cat

With the development of 3D printing and surgical techniques, various defect reconstruction methods after tumor resection have been applied not only in humans but also in veterinary medicine. This report describes a case of reconstruction after hemipelvectomy for an osteoma in a cat using a 3D-printed pelvic endoprosthesis and micro total hip replacement (mTHR). A 5-year-old spayed female Turkish Angora cat was referred for a 1-month history of constipation and intermittent weight-bearing lameness in the left hindlimb. An osteoma in the pelvis measuring 4.5 × 3 × 5.4 cm was identified based on diagnostic examinations. A left mid-to-caudal partial and right caudal partial hemipelvectomy, and a left femoral head and neck osteotomy, were planned to remove the mass. Reconstruction of the bone defect using 3D-printed metal endoprosthesis and mTHR in the left hindlimb was intended. During right caudal partial hemipelvectomy, right femoral head and neck osteotomy was performed because there was infiltration in the medial wall of the acetabulum. Histopathological examination confirmed the diagnosis of an osteoma. Two weeks post-surgery, surgical debridement and femoral stem removal were performed because of delayed wound healing and sciatic neurapraxia, leading to femoral stem dislocation from the cup. The delayed wound healing and sciatic neurapraxia were appropriately addressed. The cat regained normal weight and defecation 4 weeks post-operatively. Two years post-surgery, the patient recovered with an almost normal gait. Hemipelvectomy with 3D-printed endoprosthesis provides a safe surgical option with favorable outcomes for neoplasms in the pelvis of cats.

New adjustable modular hemipelvic prosthesis replacement with 3D-print osteotomy guide plate used in periacetabular malignant tumors: a retrospective case series

BACKGROUND

Periacetabular malignant tumor seriously endangers the life and health of patients. Hemipelvic replacement provides a good method for patients who want complete resection of the tumor while retaining or restoring the function of the affected limb.

OBJECTIVE

To investigate the performance and clinical application of the new adjustable modular hemipelvic prosthesis and to compare the effects of three kinds of hemipelvic prosthesis.

METHODS

In this study, 23 patients, with an average age of 44.6 years (21-75 years), were collected, who received hemipelvic replacement with new adjustable, modular, and screw-rod system hemipelvic prosthesis. Preoperative preparation was conducted on them, and operative complications were recorded. Postoperative functional follow-up was performed regularly.

RESULTS

The average operation time was 319 min (170-480 min), and the average blood loss was 2813 ml (1000 mL-8000 ml). The incidence of complications was 47.8%, and type A (wound-related complications) had the highest incidence (34.8%). Postoperative dislocation occurred in 3 cases (13.0%), and no dislocation occurred in the new adjustable modular hemipelvic prosthesis group. The average MSTS score of the patients was 18.6 (10-23), and the average Harris score was 73.7 (53-87).

CONCLUSIONS

The new adjustable modular hemipelvic prosthesis has the feasibility of reconstruction and good functional outcome, making it ideal for periacetabular tumors. Furthermore, preoperative tumor-feeding artery embolization and abdominal aortic balloon implantation may be an effective choice to reduce intraoperative blood loss and facilitate the operation of tumor resection.

Advances in the Application of Three-dimensional Printing for the Clinical Treatment of Osteoarticular Defects

As a promising manufacturing technology, three-dimensional (3D) printing technology is widely used in the medical field. In the treatment of osteoarticular defects, the emergence of 3D printing technology provides a new option for the reconstruction of functional articular surfaces. At present, 3D printing technology has been used in clinical applications such as models, patient-specific instruments (PSIs), and customized implants to treat joint defects caused by trauma, sports injury, and tumors. This review summarizes the application status of 3D printing technology in the treatment of osteoarticular defects and discusses its advantages, disadvantages, and possible future research strategies.

Clinical Outcome and Fracture Risk Prediction of Benign Bone Tumors on the Acetabular Dome: 7-Year Clinical Experience and a Finite Element Analysis

The treatment of benign pelvic lesions and tumors is still a challenge in clinical orthopedics. The surgical procedure was complicated and the postoperative complication was hard to avoid usually. The purpose of this study is to analyze the clinical outcome and predict the fracture risk of benign bone tumors on acetabular dome by finite element analysis. In our research, clinical data of 25 patients were collected from January 2010 to January 2017, including basic information of patients, reconstruction methods, complications, and postoperative MSTS function scores. Finite element analysis (FEA) was used to predict the fracture risk when a benign tumor involved an acetabular dome. 25 patients were followed up for 37.5 ± 5.6 (ranging from 24 to 78) months. Intraoperative bleeding was 100–3000 ml (mean 858.3 ml). The postoperative MSTS93 score was 19.61 ± 7.32 before operation and 26.28 ± 15.59 at the last follow-up. The results of finite element analysis suggest that there was a high risk for pathological fracture in the following: both columns were damaged by tumors; the anterior column and 50% of the posterior column were affected. Other cases were in the low fracture risk group. Based on this study, we believe that, according to the risk assessment results of tumor cavity fracture suggested by the FEA results, combined with the nature of tumor, it may become a useful tool which is a great significance to guide the operation plan, select the operation time, and guide the postoperative functional exercise.

Leaving half the acetabulum in pelvic resections improves hip function. Is there a need to revisit conventional pelvic resections?

BACKGROUND

Conventional periacetabular pelvic resections are associated with poor functional outcomes. Resections through surgical corridors beyond the conventional margins may be helpful in retaining greater function without compromising the oncological margins.

METHODS

The study included a retrospective review of 82 cases of pelvic resections for pelvic tumors. Outcomes of acetabulum preservation (Group A) were compared with complete acetabular resection (Group B). Also, we compared outcomes of Type I + half resections (Group 1) with Type I + II resections (Group 2), and Type III + half resections (Group 3) with Type II + III resections (Group 4).

RESULTS

Group A (n = 44) had significantly better functional outcome than Group B (n = 38) with average MSTS93 score 22.3 versus 20.1 and average HHS 91.3 versus 82.5 (p < 0.001). Group 1 (n = 14) and Group 2 (n = 12) had similar functional outcomes (mean MSTS93 score 22.07 vs. 21.58 [p = 0.597] and mean HHS 90.37 vs. 86.51 [p = 0.205]). Group 3 (n = 11) had significantly better functional outcome than Group 4 (n = 17), with mean MSTS93 score 22.8 versus 19.7 (p < 0.001) and mean HHS 92.3 versus 80.1 (p < 0.001). Oncological outcomes were similar among the groups.

CONCLUSION

Transacetabular pelvic resections provide functional benefit over conventional resections without compromising oncological margins. There is a need to revisit and revise the pelvic resection planes.

Chondrosarcoma of the proximal radius treated by wide resection and reconstructed by 3D printed implant: A case report and description of surgical technique

Introduction

Chondrosarcoma is the second most common primary malignancy of bone that can occur in multiple locations in the skeleton. It has been rarely reported in the proximal radius. While surgical resection is the primary treatment modality for individuals with localized disease, reconstruction can be challenging in the elbow joint due to its complex anatomy. 3D printing technology can be used in such complex cases to restore the normal anatomy after resection.

Case presentation

We present a case of mesenchymal chondrosarcoma in a 33-year-old male occurring in the proximal radius, restricting his elbow motion. That was resected and reconstructed using 3D modeling. Restoring a functional range of motion without instability.

Discussion

Many surgical options for chondrosarcoma presented over the years including en bloc resection, resection with or without reconstruction, or amputation. Usage of 3D modeling in the orthopedic surgery field is relatively new and it can be used in pre-operative planning and shortens surgical time. 3D printing in our case helped in obtaining a full range of motion (flexion, extension, pronation, and supination) for the patient.

Conclusion

It's important to reconstruct elbow joint support structure and function after resection of such a large malignant tumor in young patients. We used 3D printed implant to maintain a functional limb and it was an excellent alternative treatment.

•

Chondrosarcoma occurring in the proximal radius is very rare. Up to our knowledge, this is the second case report.

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We report a case of proximal radius chondrosarcoma managed by reconstruction with Three-Dimension printed implant.

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3D printing in the field of orthopedic surgery is relatively new and has upscaled medical management.

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A description of a surgical technique to reconstruct proximal radius and maintaining full range of motion of the elbow.

Clinical application of 3D-printed patient-specific guide plate combined with computer navigation in acetabular reconstruction following resection of periacetabular tumors

Background

The precise acetabular reconstruction has historically been a challenging procedure. 3D-printed patient-specific guide (PSG) and computer navigation (CN) technologies have been used to assist acetabular component positioning and pelvic reconstruction. This precise reconstruction approach may translate into clinical benefit.

Methods

The clinical data of 84 patients who underwent periacetabular malignant tumor resection and screw-rod-acetabular cage system reconstruction in our center from January 2013 to December 2020 were retrospectively analyzed. Patients were divided into four groups: free hand (FH) group, PSG group, CN group, and PSG combined with computer navigation (PSG + CN) group. The operation time, intraoperative blood loss, and number of fluoroscopy views were recorded. The oncological prognosis, radiographic measurements of the acetabulum, limb function data, and postoperative complications were compared among groups. And finally, we evaluated the risk factors for mechanical failure of the prosthesis.

Results

The postoperative X-ray and computed tomography (CT) scan revealed that the vertical offset discrepancy (VOD) between affected side and contralateral side was 8.4±1.9, 5.9±2.2, 4.1±1.3, and 2.4±1.2 mm in each groups; the horizontal offset discrepancy (HOD) was 9.0±1.9, 6.1±2.2, 3.2±1.3, and 2.1±1.2 mm, correspondingly; the abduction angle discrepancy (ABAD) was 8.6°±1.8°, 5.6°±2.0°, 2.5°±1.3°, and 1.8°±0.9°, respectively; the anteversion angle discrepancy (ANAD) was 5.9°±1.6°, 3.6°±1.7°, 2.9°±1.6°, and 1.9°±0.9°, correspondingly. Statistical results show that the PSG + CN group was superior to the FH group and the PSG group in terms of acetabular position and limb function (P<0.05). Body mass index (P=0.040) and resection type (P=0.042) were found to be the high-risk factors for mechanical failure of the prosthesis.

Conclusions

PSG + CN has potential advantages in improving the accuracy and safety of acetabular positioning and reconstruction.

Periacetabular reconstruction following limb-salvage surgery for pelvic sarcomas

Limb-salvage surgery for pelvic sarcomas remains one of the most challenging surgical procedures for musculoskeletal oncologists. In the past several decades, various surgical techniques have been developed for periacetabular reconstruction following pelvic tumor resection. These methods include endoprosthetic reconstruction, allograft or autograft reconstruction, arthrodesis, and hip transposition. Each of these procedures has its own advantages and disadvantages, and there is no consensus or gold standard for periacetabular reconstruction. Consequently, this review provides an overview of the clinical outcomes for each of these reconstructive options following pelvic tumor resections. Overall, high complication rates are associated with the use of massive implants/grafts, and deep infection is generally the most common cause of reconstruction failure. Functional outcomes decline with the occurrence of severe complications. Further efforts to avoid complications using innovative techniques, such as antibiotic-laden devices, computer navigation, custom cutting jigs, and reduced use of implants/grafts, are crucial to improve outcomes, especially in patients at a high risk of complications.

Individualized 3D printing-assisted repair and reconstruction of neoplastic bone defects at irregular bone sites: exploration and practice in the treatment of scapular aneurysmal bone cysts

BACKGROUND

The irregular anatomical shape and complex structures of irregular bones make it more difficult to repair and reconstruct bone defects in irregular bones than in the long bones of the extremities. Three-dimensional (3D) printing technology can help to overcome the technical limitations of irregular bone repair by generating simulations that enable structural integration of the lesion area and bone structure of the donor site in all directions and at multiple angles. Thus, personalized and accurate treatment plans for restoring anatomical structure, muscle attachment points, and maximal function can be made. The present study aimed to investigate the ability of 3D printing technology to assist in the repair and reconstruction of scapular aneurysmal ABC defects.

METHODS

The study included seven patients with ABCs of the scapula. Based on computed tomography (CT) data for the patient, the scapula (including the defect) and pelvis were reconstructed using Mimics Medical software. The reconstructed scapula model was printed using a 3D printer. Before the operation, the model was used to design the surgical approach and simulate the operation process, to determine the length and radius of the plate and the number and direction of screws, and to determine the bone mass of the ilium and develop reasonable strategies for segmentation and distribution. The operation time, amount of bleeding, length and radius of the plate, and direction and number of screws were recorded.

RESULTS

The average duration of follow-up was 25.6 months, and none of the seven patients experienced recurrence during the follow-up period. The surgical approach, the length and radius of internal fixation, and the number and direction of screws were consistent with the designed operation plan. Patients gradually recovered the anatomical structure of the scapula and function of the shoulder joint.

CONCLUSIONS

In the treatment of bone defects caused by irregular bone tumors, 3D printing technology combined with surgery has the advantages of less trauma, short operation time, less bleeding and reducing the difficulty of operation, which can reduce the waste of bone graft, and more complete reconstruction of the anatomical structure of the defective bone.

A Review on Development of Bio-Inspired Implants Using 3D Printing

Biomimetics is an emerging field of science that adapts the working principles from nature to fine-tune the engineering design aspects to mimic biological structure and functions. The application mainly focuses on the development of medical implants for hard and soft tissue replacements. Additive manufacturing or 3D printing is an established processing norm with a superior resolution and control over process parameters than conventional methods and has allowed the incessant amalgamation of biomimetics into material manufacturing, thereby improving the adaptation of biomaterials and implants into the human body. The conventional manufacturing practices had design restrictions that prevented mimicking the natural architecture of human tissues into material manufacturing. However, with additive manufacturing, the material construction happens layer-by-layer over multiple axes simultaneously, thus enabling finer control over material placement, thereby overcoming the design challenge that prevented developing complex human architectures. This review substantiates the dexterity of additive manufacturing in utilizing biomimetics to 3D print ceramic, polymer, and metal implants with excellent resemblance to natural tissue. It also cites some clinical references of experimental and commercial approaches employing biomimetic 3D printing of implants.

Mid- and Long-Term Follow-Up Efficacy Analysis of 3D-Printed Interbody Fusion Cages for Anterior Cervical Discectomy and Fusion

OBJECTIVE

To evaluate the safety and stability of 3D-printed interbody fusion cages (3D-printed cages) in anterior cervical discectomy and fusion (ACDF) by investigating the mid- and long-term follow-up outcomes.

METHODS

In this prospective study, the clinical data of 30 patients with CSM admitted to the Second Hospital of Shanxi Medical University from May 2012 to May 2014 were analyzed. The cohort comprised 18 males and 12 females with an average age of 60.22 ± 3.2 years. All patients were examined by X-ray, CT and MRI before the operation. A total of 30 cases of CSM were treated by ACDF with 3D printed cage implantation. Mid- and long-term follow-ups were performed after the surgery. Clinical efficacy was evaluated by comparing the JOA score, SF-36 score, change in neurological function, cervical curvature index (CCI), vertebral intervertebral height (VIH) and fusion rate before the operation, 6 months after the operation, and at the last follow-up.

RESULTS

Two of the 30 patients were lost to follow-up. The remaining patients were followed up for 48-76 (65.23 ± 3.54) months. The patients recovered satisfactorily with a significant clinical effect. The JOA score increased meanfully and the improvement rate was 89.4% at the final follow-up. The SF-36 score increased significantly from pre- to postoperatively. The height of the intervertebral space at the last follow-up was not statistically significantly different from that at 6 months after surgery (P > 0.05), showing that the height of the intervertebral space did not change much and the severity of cage subsidence (CS) decreased. The CCI improved from pre- to postoperatively. The CCI did not change much from the 6-month follow-up to the last follow-up. and the cage rate (CR) was 100% at the 6-month and last follow-ups. No severe complications, such as spinal cord injury, esophageal fistula, cerebrospinal fluid leakage, cervical hematoma or wound infection, occurred in any of the patients.

CONCLUSION

The clinical and radiological results show that the application of 3D-printed cages in ACDF can significantly relieve symptoms. Moreover, 3D-printed cages can restore the curvature of the cervical spine, effectively maintain the intervertebral height for a long time, and prevent complications related to postoperative subsidence.

Computer Assisted Surgery and 3D Printing in Orthopaedic Oncology: A Lesson Learned by Cranio-Maxillo-Facial Surgery

Primary bone sarcomas are rare tumors and surgical resection in combination with chemo and radiation therapy is the mainstay of treatment. Some specific anatomical sites still represent a reconstructive challenge due to their complex three-dimensional anatomy. In recent years, patient specific instruments along with 3D printing technology has come to represent innovative techniques in orthopaedic oncology. We retrospectively reviewed 23 patients affected by primary bone sarcoma treated with patient-specific instruments and 3D printing custom made prostheses. At follow up after approximately two years, the infection rate was 26%, mechanical complication rate 13%, and local recurrence rate 13% (with a five-years implant survival rate of 74%). Based on our experience, patient-specific instruments and 3D custom-made prostheses represents a reliable and safe technique for improving the accuracy of resection of primary bone tumour, with a particular use in pelvic surgery ameliorating functional results.

Application of three-dimensional printing technology in peripheral hip diseases

The incidence of peripheral hip diseases is increasing every year, and its treatment is always tricky due to the complexity of hip joint anatomy and a variety of surgical methods. This paper summarizes the application research and progress of three-dimensional (3D) printing technology in different peripheral hip diseases in recent years published by PubMed from January 2017 to July 2021 with the search terms including “3D or three-dimensional, print*, and hip*. In general, the application of 3D printing technology is mainly to print bone models of patients, make surgical plans, and simulate pre-operation, customized surgical navigation templates for precise positioning or targeted resection of tissue or bone, and customized patient-specific instruments (PSI) fully conforms to the patient’s anatomical morphology. It mainly reduces operative time, intraoperative blood loss, and improves joint function. Consequently, 3D printing technology can be customized according to the patient’s disease condition, which provides a new option for treating complex hip diseases and has excellent application and development potential.

3D printing of dual-cell delivery titanium alloy scaffolds for improving osseointegration through enhancing angiogenesis and osteogenesis

BACKGROUND

The repair of large bone defects is a great challenge for orthopedics. Although the development of three-dimensional (3D) printed titanium alloy (Ti6Al4V) implants with optimized the pore structure have effectively promoted the osseointegration. However, due to the biological inertia of Ti6Al4Vsurface and the neglect of angiogenesis, some patients still suffer from postoperative complications such as dislocation or loosening of the prosthesis.

METHODS

The purpose of this study was to construct 3D printed porous Ti6Al4V scaffolds filled with bone marrow mesenchymal stem cells (BMSC) and endothelial progenitor cells (EPC) loaded hydrogel and evaluate the efficacy of this composite implants on osteogenesis and angiogenesis, thus promoting osseointegration.

RESULTS

The porosity and pore size of prepared 3D printed porous Ti6Al4V scaffolds were 69.2 ± 0.9 % and 593.4 ± 16.9 μm, respectively, which parameters were beneficial to bone ingrowth and blood vessel formation. The BMSC and EPC filled into the pores of the scaffolds after being encapsulated by hydrogels can maintain high viability. As a cell containing composite implant, BMSC and EPC loaded hydrogel incorporated into 3D printed porous Ti6Al4V scaffolds enhancing osteogenesis and angiogenesis to repair bone defects efficiently. At the transcriptional level, the composite implant up-regulated the expression levels of the osteogenesis-related genes alkaline phosphatase (ALP) and osteocalcin (OCN), and angiogenesis-related genes hypoxia-inducible factor 1 alpha (HIF-1α), and vascular endothelial growth factor (VEGF).

CONCLUSIONS

Overall, the strategy of loading porous Ti6Al4V scaffolds to incorporate cells is a promising treatment for improving osseointegration.

Venous Tumor Thrombus in Primary Bone Sarcomas in the Pelvis: A Clinical and Radiographic Study of 451 Cases

BACKGROUND

Few investigations of venous tumor thrombus (VTT) in primary pelvic bone sarcomas are available. We aimed to identify the prevalence, associated factors, and prognosis of VTT across different types of pelvic sarcomas and to propose an algorithm for management.

METHODS

We included 451 consecutive cases of primary, bone-derived, treatment-naive, pelvic sarcomas in this study. Demographic data and the results of initial laboratory tests, imaging examinations, and oncological evaluations were extracted and analyzed. Forty-four cases of VTT were diagnosed with radiographic examinations, and 18 of them were verified histologically.

RESULTS

The cohort consisted of chondrosarcomas (41.2%), osteosarcomas (30.4%), Ewing sarcomas (15.5%), bone-derived undifferentiated pleomorphic sarcomas (5.8%), and other bone sarcomas (7.1%). The prevalence of VTT was 9.8% in the whole group, and associated factors included a lactate dehydrogenase (LDH) level of ≥230.5 U/L and invasion of the L5-S1 intervertebral foramen. Patients with pelvic osteosarcoma had a high prevalence of VTT (22.6%), and the associated factors in this group included a chondroblastic subtype, an LDH level of ≥187 U/L, and invasion of the obturator foramen and the L5-S1 intervertebral foramen. Patients with VTT had a poor prognosis with a median overall survival time of 14 months. Subgroup analyses of localized pelvic osteosarcoma indicated that the presence of VTT decreased the median overall survival time (21.5 versus 54.0 months for those without VTT, p = 0.003), median recurrence-free survival time (18.6 versus 32.4 months, p = 0.020), and median metastasis-free survival time (11.2 versus 41.0 months, p < 0.001).

CONCLUSIONS

VTT is most common in patients with pelvic osteosarcoma as compared with patients with other primary bone sarcomas, and it is associated with several factors. It is a negative prognostic factor. An algorithm for management of pelvic sarcomas with VTT stratified by the classification of the VTT might be beneficial, but further validation is necessary.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Iliosacral Bone Tumor Resection Using Cannulated Screw-Guided Gigli Saw - A Novel Technique

BACKGROUND

Adequate margins are technically difficult to achieve for malignant tumors involving the sacroiliac joint due to limited accessibility and viewing window. In order to address the technical difficulties faced in iliosacral tumor resection, we proposed a technique for precise osteotomy, which involved the use of canulated screws and Gigli saw (CSGS) that facilitated directional control, anteroposterior linkage of resection points and adequate surgical margins. The purpose of the current study was to evaluate whether CSGS technique facilitated sagittal osteotomy at sacral side, and were adequate surgical margins achieved? Also functional and oncological outcomes was determined along with the noteworthy complications.

METHODS

From April 2018 to November 2019, we retrospectively reviewed 15 patients who underwent resections for primary tumors of pelvis or sacrum necessitating iliosacral joint removal using the proposed CSGS technique. Chondrosarcoma was the most common diagnosis. The osteotomy site within sacrum was at ipsilateral ventral sacral foramina in 8 cases, midline of sacrum in 5 cases, and contralateral ventral sacral foramina and sacral ala with 1 case each. The average intraoperative blood loss was 3640 mL (range, 1200 and 6000 mL) with a mean operation duration of 7.4 hours (range, 5 to 12 hours). The mean follow-up was 23.0 months (range, 18 and 39 months) for alive patients.

RESULTS

Surgical margins were wide in 12 patients (80%), wide-contaminated in 1 patient (6.7%), and marginal in 2 patients (13.3%). R0 resection was achieved in 12 (80%) patients and R1 resection in 3 patients. There were three local recurrences (20%) occurred at a mean time of 11 months postoperatively. No local recurrence was observed at sacral osteotomy. The overall one-year and three-year survival rate was 86.7% and 72.7% respectively.Complications occurred in three patients.

CONCLUSIONS

The current study demonstrated that CSGS technique for tumor resection within the sacrum and pelvis was feasible and can achieve ideal resection accuracies. The use of CSGS was associated with high likelihood of negative margin resections in the current series. Intraoperative use of CSGS appeared to be technically straightforward and allowed achievement of planned surgical margins. It is worthwhile to consider the use of CSGS technique in resection of pelvic tumors with sacral invasion and iliosacral tumors, however further follow-up at mid to long-term is warranted to observe local recurrence rate.

3D-Printed Titanium Custom-Made Prostheses in Reconstruction after Pelvic Tumor Resection: Indications and Results in a Series of 14 Patients at 42 Months of Average Follow-Up

Wide resection is currently considered the mainstay treatment for primary bone tumors. When the tumor is located in anatomically complex segments, 3D-Printed Titanium Custom-Made Prostheses (3DPTCMP) are possible reconstructive solutions. The aim of the present paper is to analyze indications, results and complications of a series of 14 patients who underwent pelvis reconstruction with 3DPTCMP after tumor removal from January 2015 to December 2019. Chondrosarcoma was the main histology; indications were tumors located in the acetabular area without enough residual bone to support a cup with an iliac stem, and tumors located near the sacrum-iliac joint. The margins were wide in 12 cases, and marginal and intralesional in one case each. In three cases, resection also included the sacrum-iliac joint, so a spine stabilization was performed and linked to the pelvic prosthesis; The average MSTS score was 46.3%; the 5-year local recurrence-free survival was 85.7%. Wound dehiscences were the main complication, resolved with multiple debridements; nevertheless, prosthesis removal was necessary in one case. Currently, the 3DPTCMP is an effective resource for reconstruction after resection of tumors located in the pelvis. Further studies are necessary to value long-term results; more strategies are necessary to try to reduce the infection rate and improve osteointegration.

Acetabular reconstruction in oncological surgery: A systematic review and meta-analysis of implant survivorship and patient outcomes

BACKGROUND

Reconstruction of the hip for peri-acetabular oncological disease remains a challenge. The objective of this study was to summarize the evidence and identify techniques utilized for primary and metastatic tumors of the acetabulum and hemipelvis.

METHODS

A systematic review of the published literature was carried out in accordance with PRISMA guidelines. MEDLINE, EMBASE and Cochrane databases identified relevant articles. Quality was assessed using the Newcastle-Ottawa Scale. The study was registered on PROSPERO.

RESULTS

53 papers were included, 16 were suitable for meta-analysis. 909 patients had primary and 1140 metastatic disease. 1094 patients underwent reconstruction with conventional total hip arthroplasty (with or without cup-cage or cement augmentation) or modifications of the Harrington procedure, collectively termed 'non-complex'. 928 patients underwent 'complex' reconstructions with either a modular hemipelvic, saddle, reverse snow-cone, custom-made or 3D-printed endoprosthesis. The most common complication was deep infection (11%) followed by dislocation (5%). Mean MSTS scores were 61.9% for 'non-complex' versus 63.2% for 'complex' reconstruction. Meta-analysis suggested increased mortality for primary (OR 3.14; 95% CI 1.15-8.54) and trends toward reduced mortality for metastatic disease (OR 0.93; 95% CI 0.26-3.29) following 'complex' versus 'non-complex' reconstruction. Reoperation rates were higher following 'complex' reconstruction for metastatic disease (OR 1.90; 95% CI 0.66-5.46) and similar for primary disease (OR 0.98; 95% CI 0.45-2.14).

CONCLUSIONS

Peri-acetabular tumors are associated with high rates of morbidity and mortality. Decisions regarding implant selection are multi-factorial with recent increase in the use of custom-made and 3D-printing technologies. Multiple factors contribute to the oncological outcome and patient function. Further research is required in order to guide optimal practice.

Remaining spine deformity after revision surgery for pelvic reconstruction and spinopelvic fixation: illustrative case

BACKGROUND

Pelvic deformity after resection of malignant pelvic tumors causes scoliosis. Although the central sacral vertical line (CSVL) is often used to evaluate the coronal alignment and determine the treatment strategy for scoliosis, it is not clear whether the CSVL is a suitable coronal reference axis in cases with pelvic deformity. This report proposes a new coronal reference axis for use in cases with pelvic deformity and discusses the pathologies of spinal deformity remaining after revision surgery.

OBSERVATIONS

A 14-year-old boy who had undergone internal hemipelvectomy and pelvic ring reconstruction 2 years prior was referred to our hospital with severe back pain. His physical and radiographic examinations revealed severe scoliosis with pelvic deformity. The authors planned a surgical strategy based on the CSVL and performed pelvic ring reconstruction using free vascularized fibula graft and spinopelvic fixation from L5 to the pelvis. After the procedure, although the patient’s back pain was relieved, his scoliosis persisted. At the latest follow-up, his spinal deformity correction was acceptable with corset bracing. Therefore, the authors did not perform additional surgeries.

LESSONS

The CSVL may not be appropriate for evaluating coronal alignment in cases with pelvic deformity. Accurate preoperative planning is required to correct spinal deformities with pelvic deformity.

Use of three-dimensional-printed custom-made prosthesis to treat unicondylar femoral defect secondary to pathological fracture caused by giant cell tumor

Objective

To evaluate the short-term effectiveness of using a three-dimensional (3D)-printed custom-made prosthesis to repair unicondylar femoral defects.

Methods

We retrospectively reviewed 26 patients with a primary pathological fracture of the distal femur caused by a giant cell tumor. All patients had unicondylar defects involving the articular surface. Twelve patients were treated with a 3D-printed custom-made prosthesis to repair the unicondylar defect (3D-printed group). The other 14 patients were treated with total knee replacement (TKR group). The operation time, blood loss, Musculoskeletal Tumor Society score, range of motion, local recurrence, and complications were statistically compared.

Results

The operation time was significantly shorter and the blood loss was significantly less in the 3D-printed group than in the TKR group. The Musculoskeletal Tumor Society scores were significantly higher in the 3D-printed group than in the TKR group from 3 to 24 months postoperatively. The range of motion was significantly better in the 3D-printed group than in the TKR group at 6 and 9 months postoperatively.

Conclusions

3D-printed custom-made prostheses provide better short-term functional results than does TKR.

Impact of Surgical Resection and Reasons for Poor Prognosis of Pelvic Osteosarcoma Based on the Bone Tumor Registry in Japan

Simple Summary

Pelvic osteosarcoma has a poor prognosis compared to osteosarcomas in other locations, and the reasons for this remains unknown. Surgical resection of pelvic osteosarcoma is technically demanding and often results in dysfunction and complications. In this study, we investigated the reasons underlying the poor prognosis of pelvic osteosarcoma by comparing it to femoral osteosarcoma using data from the Bone Tumor Registry in Japan. We used propensity score analysis to determine whether surgical resection of pelvic osteosarcoma improved its prognosis. We demonstrated that pelvic osteosarcoma had a poor prognosis because it occurred more often in the elderly, often had a larger tumor size, and had metastasis at presentation more often in comparison to femoral osteosarcoma. These three factors were also associated with the non-surgical treatment of pelvic osteosarcoma, which also led to a poor outcome. The overall survival rate was only comparable in pelvic osteosarcoma and femoral osteosarcoma in cases treated with surgical resection. Propensity score analysis revealed that surgical treatment improved the prognosis of pelvic osteosarcoma. As such, we propose that surgical resection should be considered based on tumor stage and patient age in order to improve the prognosis of pelvic osteosarcoma.

Abstract

Pelvic osteosarcoma has a poor prognosis compared to osteosarcomas in other locations, and the reasons for this remain unknown. Surgical resection of pelvic osteosarcoma is technically demanding and often results in dysfunction and complications. In this study, we investigated the reasons underlying the poor prognosis of pelvic osteosarcoma by comparing it to femoral osteosarcoma using data from the Bone Tumor Registry in Japan. We used propensity score analysis to determine whether surgical resection of pelvic osteosarcoma improved its prognosis. We demonstrated that pelvic osteosarcoma had a poor prognosis because it occurred more often in the elderly, often had larger tumor size, and had metastasis at presentation more often in comparison to femoral osteosarcoma. These three factors were also associated with the non-surgical treatment of pelvic osteosarcoma, which also led to a poor outcome. The overall survival rate was only comparable in pelvic osteosarcoma and femoral osteosarcoma in cases treated with surgical resection. Propensity score analysis revealed that surgical treatment improved the prognosis of pelvic osteosarcoma. As such, we propose that surgical resection should be considered based on tumor stage and patient age in order to improve the prognosis of pelvic osteosarcoma.

Sacroplasty Augmentation of Instrumented Pelvic Reconstruction After High Sacrectomy: A Technical Case Report

BACKGROUND AND IMPORTANCE

En bloc resection of sacral tumors is the most effective treatment to help prevent recurrence. Sacrectomy, however, can be destabilizing, depending on the extent of resection. Various surgical techniques for improving stability and enabling early ambulation have been proposed.

CLINICAL PRESENTATION

Here, we report a case in which we use PMMA (poly[methyl methacrylate]) to augment pelvic instrumentation to improve mechanical stability after sacrectomy for en bloc resection of a solitary fibrous tumor.

CONCLUSION

We highlight the use of sacroplasty augmentation of pelvic ring reconstruction to provide biomechanical stability without the need for fusion of any mobile spine segments, which allowed for early patient ambulation and no appreciable loss of range of motion or mobility.

Three-dimensional printing-based personalized limb salvage and reconstruction treatment of pelvic tumors

BACKGROUND AND OBJECTIVES

The treatment of pelvic tumors is widely recognized to be challenging. The purpose of this study was to evaluate the efficacy of personalized three-dimensional (3D) printing-based limb salvage and reconstruction treatment for pelvic tumors.

METHODS

Twenty-eight pelvic tumor patients were enrolled. 3D printing lesion models and osteotomy templates were prepared for surgery planning, prosthesis design, and osteotomy assistance during surgery. 3D printing-based personalized pelvic prostheses were manufactured and used in all 28 patients. Follow-up of postoperative survival, prosthesis survival, imaging examinations, and Musculoskeletal Tumor Society (MSTS) lower limb functional scores were carried out.

RESULTS

The mean follow-up period was 32.2 months, during which 16 patients had disease-free survival, 3 survived with the disease, and 9 died. The prostheses were stable, and the mean offset of the center of rotation was 5.48 mm. The prosthesis-bone interface showed good integration. For the 19 surviving patients, the mean MSTS lower limb functional score was 23.2. Postoperative complications included superficial infection in six patients and hip dislocation in three patients.

CONCLUSIONS

Personalized 3D printing-based limb salvage and reconstruction was an effective treatment for pelvic tumors. Our patients achieved good early postoperative efficacy and functional recovery.

3D printing guide plate for accurate hemicortical bone tumor resection in metaphysis of distal femoral: a technical note

BACKGROUND

Surgical resection and reconstruction for low-grade bone sarcoma in the metaphysis of the distal femur remain challenging. We hypothesized that 3D printing osteotomy guide plate could assist to accurately resect the tumor lesion and save the joint function.

METHODS

From January 2017 to August 2019, five patients diagnosed with low-grade bone sarcoma in the metaphysis of the distal femur were treated with hemicortical resection using 3D printing guide plate. Autologous bone graft was inactivated in a high-temperature water bath and re-implanted in situ fixed with plate and screw. Patients were followed up from 17 to 33 months. The Musculoskeletal Tumor Society Score was used to evaluate the joint function. X-ray was used to evaluate the bone union.

RESULTS

One patient was paracorticular osteosarcoma, and four cases had highly differentiated chondrosarcoma. All cases were involved in the metaphysis of the distal femur. Patients were followed up from 13 to 33 months, with an average of 23.6 months. There was neither post-operation infection, internal fixation loosening, nor fracture occurrence in any of the patients. The Musculoskeletal Tumor Society Score averaged at 28.1, while the International Society of Limb Salvage imaging score examination averaged 89.8%.

CONCLUSIONS

Here, we demonstrate that the 3D printing osteotomy guide plate-assisted hemicortical bone resection is a beneficial strategy to effectively resect the primary low-grade malignant bone tumors in the metaphysis of the distal femur and retained satisfied joint function.

Three-dimensional-printed custom-made hemipelvic endoprosthesis for the revision of the aseptic loosening and fracture of modular hemipelvic endoprosthesis: a pilot study

Background

The aims of this pilot study were (1) to assess the efficacy of 3D-printed custom-made hemipelvic endoprosthesis in restoring the natural location of acetabulum for normal bodyweight transmission; (2) to evaluate the short-term function of the revision with this endoprosthesis and (3) to identify short-term complications associated with the use of this endoprosthesis.

Methods

Between February 2017 and December 2017, seven patients received revision with 3D-printed custom-made hemipelvic endoprosthesis. The body weight moment arm (BWMA) and cup height discrepancy (CHD) after primary and revisional surgery were analyzed to assess acetabulum location with plain radiography. After a median follow-up duration of 29 months (range 24–34), the function was evaluated with the Musculoskeletal Tumor Society (MSTS-93) score and Harris hip score (HHS). Complications were recorded by chart review.

Results

The acetabulum locations were deemed reasonable, as evaluated by median BWMA (primary vs. revision, 10 cm vs. 10 cm) and median CHD (primary vs. revision, 10 mm vs. 8 mm). The median MSTS-93 score and HHS score were 21 (range 18–23) and 78 (range 75–82) after the revision. No short or mid-term complication was observed in the follow-up of this series.

Conclusions

Revision with 3D-printed custom-made hemipelvic endoprostheses benefited in reconstructing stable pelvic ring and natural bodyweight transmission for patients encountering the aseptic loosening and fracture of modular hemipelvic endoprosthesis. The revision surgery and appropriate rehabilitation program improved patients’ function to a median MSTS score of 22 and pain-free ambulation. The incidence of the complications was low via this individualized workflow.

Three-dimensional-printed customized prosthesis for pubic defect: clinical outcomes in 5 cases at a mean follow-up of 24 months

Background

Pubic defects resulting from type III hemipelvectomy are commonly not reconstructed due to the need to preserve the weight-bearing axis. However, the opening of the anterior pelvic ring will inevitably lead to increased pelvic instability. To improve long-term pelvic stability, three-dimensional (3D)-printed customized prostheses were designed to reconstruct pubic defects. This study presents and evaluates the short-term clinical outcomes and complications from the use of this construct.

Methods

Five patients who underwent type III hemipelvectomy and 3D-printed customized prosthesis reconstruction at our institution between 2017 and 2019 were retrospectively analysed. Operation time and blood loss during the operation were recorded. Local and functional recovery was assessed. Prosthetic position and osseointegration were evaluated. Oncology results and complications were recorded.

Results

The prostheses consisted of three with stems and two without. The mean follow-up time was 23.6 months. At the last follow-up, all five patients were alive with no evidence of disease. No deep infections or local recurrence had occurred. The mean blood loss and mean intraoperative time were 1680 ml and 294 min, respectively. The mean functional MSTS score at the final follow-up was 29.8. Fretting wear around the prosthetic stem was found in 3 patients, while bone wear on the normal-side pubis was found in 2 patients. Osseointegration was observed in all patients.

Conclusions

3D-printed customized prostheses for reconstructing pubic bone defects after type III hemipelvectomy showed acceptable early outcomes. The good outcomes were inseparable from the precision prosthesis design, strict surgical procedures, and sensible postoperative management.

Three-dimensional printed implant for reconstruction of pelvic bone after removal of giant chondrosarcoma: a case report

Background

Three-dimensional (3D) reconstruction has been used for various diseases, but few reports have described its application in pelvic reconstruction after removal of giant chondrosarcoma. Case reports describing the clinical application of personalized 3D-printed titanium implants are needed for future clinical reference.

Case presentation: We herein describe a 29-year-old woman with a giant chondrosarcoma treated with a personalized 3D titanium implant. The surgery was successful, and the patient recovered with significant pain relief and good functional recovery after the surgery. No implant-related complications occurred during the 12-month follow-up. The current case represents successful application of 3D printing technology to the treatment of a massive bone defect due to the removal of a giant osteoporotic tumor.

Conclusions

Personalized 3D titanium implants can be used in the reconstruction of massive bone defects after the removal of giant pelvic sarcomas. The methodology and results described in the current case report can be a used as reference in the treatment of similar cases in future.

Pelvic Chondrosarcoma Treated by En Bloc Resection with Patient-Specific Osteotomy Guides and Reimplantation of the Extracorporeally Irradiated Bone as an Osseocartilaginous Structural Orthotopic Autograft: A Report of Two Cases with Description of the Surgical Technique

Primary tumors of the pelvis are considered difficult to treat due to the complex anatomy and the proximity of important neurovascular structures. The surgical armamentarium for the treatment of these tumors has evolved with the help of cutting-edge technology from debilitating hemipelvectomies to solutions such as precise resections guided by patient-specific instruments or computer navigation and reconstruction by modular prostheses, 3D-printed custom-made implants, or orthotopic autograft reimplantation after extracorporeal irradiation. Different combinations of these techniques have been described in the literature with various rates of success. We present two cases of pelvic chondrosarcomas successfully treated by a combination of periacetabular resection with patient-specific osteotomy guides and orthotopic reimplantation of the extracorporeally irradiated autograft resulting in retention of the native hip.

Reconstruction with customized, 3D-printed prosthesis after resection of periacetabular Ewing's sarcoma in children using "triradiate cartilage-based" surgical strategy:a technical note

Background

Surgery for Ewing sarcoma involving acetabulum in children is challenging. Considering the intrinsic structure of immature pelvis, trans-acetabular osteotomy through triradiate cartilage might be applied. The study was to describe the surgical technique and function outcomes of trans-acetabular osteotomy through triradiate cartilage and reconstruction with customized, 3D-printed prosthesis.

Methods

Two children with periacetabular ES were admitted to our hospital. The pre-operative imaging showed the triradiate cartilage was not penetrated or wholly affected by tumor. After neoadjuvant chemotherapy, the tumor was excised by trans-acetabular osteotomy basing on “triradiate cartilage strategy” and the acetabulum was reconstructed with the customized, 3D-printed prosthesis. The prosthesis was designed in Mimics software basing on the images from CT, optimized by topology technique, and examined in FE model. After implantation, the oncological and functional outcomes were evaluated with radiography, CT, and MSTS score.

Results

The operation time and intra-operative blood loss in these two children were 3.5h, 2.5h and 300 ml, 600 ml, respectively. The postoperative specimen showed the tumor was en bloc removed with safe margin. In the latest follow-up (48 months and 24 months), both patients were free of disease and had satisfactory function according to MSTS score. The radiography indicated the prosthesis fit the defect well without loosening.

Conclusion

The customized, 3D-printed prosthesis could provide optimal reconstruction of pelvic ring and satisfactory hip function after trans-acetabular osteotomy in children.

The translational potential of this article

This study provides promising results of implantation of customized 3D printing prosthesis in children’s pelvic sarcoma, which may bring a new design method for orthopaedic implants.

Current Status of Management and Outcome for Patients with Ewing Sarcoma

Ewing sarcoma is the second most common bone sarcoma in children after osteosarcoma. It is a very aggressive malignancy for which systemic treatment has greatly improved outcome for patients with localized disease, who now see survival rates of over 70%. However, for the quarter of patients presenting with metastatic disease, survival is still dismal with less than 30% of patients surviving past 5 years. Patients with disease relapse, local or distant, face an even poorer prognosis with an event-free 5-year survival rate of only 10%. Unfortunately, Ewing sarcoma patients have not yet seen the benefit of recent years' technical achievements such as next-generation sequencing, which have enabled researchers to study biological systems at a level never seen before. In spite of large multinational studies, treatment of Ewing sarcoma relies entirely on chemotherapeutic agents that have been largely unchanged for decades. As many promising modern therapies, including monoclonal antibodies, small molecules, and immunotherapy, have been disappointing to date, there is no clear candidate as to which drug should be investigated in the next large-scale clinical trial. However, the mechanisms driving tumor development in Ewing sarcoma are slowly unfolding. New entities of Ewing-like tumors, with fusion transcripts that are related to the oncogenic EWSR1-FLI1 fusion seen in the majority of Ewing tumors, are being mapped. These tumors, although sharing much of the same morphologic features as classic Ewing sarcoma, behave differently and may require a different treatment. There are also controversies regarding local treatment of Ewing sarcoma. The radiosensitive nature of the disease and the tendency for Ewing sarcoma to arise in the axial skeleton make local treatment very challenging. Surgical treatment and radiotherapy have their pros and cons, which may give rise to different treatment strategies in different centers around the world. This review article discusses some of these controversies and reproduces the highlights from recent publications with regard to diagnostics, systemic treatment, and surgical treatment of Ewing sarcoma.

The application of 3D-printing technology in pelvic bone tumor surgery

BACKGROUND

Three-dimensional (3D)-printing technology provides an advanced approach to pelvic bone tumor resection and reconstruction. However, only a few cases of pelvic bone tumor surgery using 3D-printing have been reported due to limited time since the introduction of the new implant. This study introduces pelvic bone tumor surgeries using 3D-printed bone-cutting guides and implants.

METHODS

This single-center retrospective review included 12 patients who underwent malignant pelvic bone tumor surgeries using a 3D-printed bone-cutting guide and/or implant. Clinical information was collected regarding patient demographics, tumor characteristics, pathologic diagnosis, surgery details, and functional recovery.

RESULTS

Type I internal hemipelvectomy was performed using 3D-printed bone-cutting guides for 4 patients that underwent cavitary bone tumor resection of the ilium. For 3 of these 4 patients, cavitary bone defects were filled with structural allobone graft precisely trimmed by the 3D-printed allograft-shaping guide (n = 1) and 3D-printed mesh-style titanium spacer (n = 2). For type II and III areas, one and two patients, respectively, underwent 3D-printing-assisted surgery. Five patients underwent type I, II, and III pelvic resection using 3D-printed cutting guides and reconstruction with 3D-printed implants. In all patients, independent gait was recovered except for a patient who underwent hindquarter amputation 4 months postoperatively because of local recurrence.

CONCLUSIONS

This study provides preliminary, short-term data on the efficacy and safety of pelvic bone tumor surgery using 3D-printing.

Additive manufacturing pertaining to bone: Hopes, reality and future challenges for clinical applications

For the past 20 years, the democratization of additive manufacturing (AM) technologies has made many of us dream of: low cost, waste-free, and on-demand production of functional parts; fully customized tools; designs limited by imagination only, etc. As every patient is unique, the potential of AM for the medical field is thought to be considerable: AM would allow the division of dedicated patient-specific healthcare solutions entirely adapted to the patients' clinical needs. Pertinently, this review offers an extensive overview of bone-related clinical applications of AM and ongoing research trends, from 3D anatomical models for patient and student education to ephemeral structures supporting and promoting bone regeneration. Today, AM has undoubtably improved patient care and should facilitate many more improvements in the near future. However, despite extensive research, AM-based strategies for bone regeneration remain the only bone-related field without compelling clinical proof of concept to date. This may be due to a lack of understanding of the biological mechanisms guiding and promoting bone formation and due to the traditional top-down strategies devised to solve clinical issues. Indeed, the integrated holistic approach recommended for the design of regenerative systems (i.e., fixation systems and scaffolds) has remained at the conceptual state. Challenged by these issues, a slower but incremental research dynamic has occurred for the last few years, and recent progress suggests notable improvement in the years to come, with in view the development of safe, robust and standardized patient-specific clinical solutions for the regeneration of large bone defects.

Surgical Advances in Osteosarcoma

Simple Summary

Osteosarcoma (OS) is the most common bone cancer in children. OS most commonly arises in the legs, but can arise in any bone, including the spine, head or neck. Along with chemotherapy, surgery is a mainstay of OS treatment and in the 1990s, surgeons began to shift from amputation to limb-preserving surgery. Since then, improvements in imaging, surgical techniques and implant design have led to improvements in functional outcomes without compromising on the cancer outcomes for these patients. This paper summarises these advances, along with a brief discussion of future technologies currently in development.

Abstract

Osteosarcoma (OS) is the most common primary bone cancer in children and, unfortunately, is associated with poor survival rates. OS most commonly arises around the knee joint, and was traditionally treated with amputation until surgeons began to favour limb-preserving surgery in the 1990s. Whilst improving functional outcomes, this was not without problems, such as implant failure and limb length discrepancies. OS can also arise in areas such as the pelvis, spine, head, and neck, which creates additional technical difficulty given the anatomical complexity of the areas. We reviewed the literature and summarised the recent advances in OS surgery. Improvements have been made in many areas; developments in pre-operative imaging technology have allowed improved planning, whilst the ongoing development of intraoperative imaging techniques, such as fluorescent dyes, offer the possibility of improved surgical margins. Technological developments, such as computer navigation, patient specific instruments, and improved implant design similarly provide the opportunity to improve patient outcomes. Going forward, there are a number of promising avenues currently being pursued, such as targeted fluorescent dyes, robotics, and augmented reality, which bring the prospect of improving these outcomes further.

Surgical planning of pelvic tumor using multi-view CNN with relation-context representation learning

Limb salvage surgery of malignant pelvic tumors is the most challenging procedure in musculoskeletal oncology due to the complex anatomy of the pelvic bones and soft tissues. It is crucial to accurately resect the pelvic tumors with appropriate margins in this procedure. However, there is still a lack of efficient and repetitive image planning methods for tumor identification and segmentation in many hospitals. In this paper, we present a novel deep learning-based method to accurately segment pelvic bone tumors in MRI. Our method uses a multi-view fusion network to extract pseudo-3D information from two scans in different directions and improves the feature representation by learning a relational context. In this way, it can fully utilize spatial information in thick MRI scans and reduce over-fitting when learning from a small dataset. Our proposed method was evaluated on two independent datasets collected from 90 and 15 patients, respectively. The segmentation accuracy of our method was superior to several comparing methods and comparable to the expert annotation, while the average time consumed decreased about 100 times from 1820.3 seconds to 19.2 seconds. In addition, we incorporate our method into an efficient workflow to improve the surgical planning process. Our workflow took only 15 minutes to complete surgical planning in a phantom study, which is a dramatic acceleration compared with the 2-day time span in a traditional workflow.

Do irradiated osteo-articular recycled tumor autografts still hold promise for biological joint reconstruction? Our experience with acetabular and proximal ulna ECRT

BACKGROUND

Joint reconstruction following resection of malignant bone tumors is challenging in itself in spite of several options in hand. Ability to restore joint anatomy, function and mobility while achieving optimal oncological outcomes are the requirement of reconstructions today. While biological reconstructions (allograft or recycled tumor autografts) following tumor bone surgery are popular for intercalary resections not involving the joint, their use for osteo-articular reconstructions are associated with concerns over cartilage and joint health. We have used extracorporeal radiation therapy (ECRT) and re-implantation of the osteoarticular segment as a size matched recycled tumor autograft reconstruction after complex acetabular and proximal ulnar resections; owing to the lack of significantly superior reconstruction alternatives in these locations and also review the current literature on other biological/non-biological reconstruction options.

QUESTIONS/PURPOSES

(1) What are the oncological, reconstruction and functional outcomes with osteo-articular reconstruction using ECRT and re-implantation of recycled tumor autograft for the acetabulum and olecranon? (2) Is there an evidence of cartilage loss, joint damage or avascular necrosis resulting from irradiation of the articular autograft?

METHODS

19 patients with primary bone tumors underwent limb salvage surgery with en-bloc resection and reconstruction using the resected articular tumor bone after treating it with extra-corporeal irradiation of 50-60Gy. These included 16 acetabular and 3 proximal ulnar. While all patients were included for oncological assessment; minimum follow-up of 24 months was considered for final outcome assessment of function and joint status.

RESULTS

MSTS scores of the 16 acetabular reconstruction patients with minimum 2 years follow-up was 87% (26/30). Neither delayed union, non-union at osteotomy sites nor was any fractures reported in the irradiated graft. There was no local recurrence within the irradiated graft and only 1 patient required graft excision for uncontrolled infection. All 3 patients of proximal ulna reconstruction achieved healing and full range of movement of the elbow. Scores of MSTS: 100% (30/30), MEPS: 100 and DASH: zero was achieved. Two patients developed osteonecrosis of the femoral head; one requiring a joint replacement and one awaiting replacement. One patient of acetabular reconstruction has joint space narrowing on radiographs with mild clinical symptoms.

CONCLUSIONS

Extracorporeal radiotherapy and re-implantation after osteo-articular resection is an oncologically safe option offering promising outcome in our small series. The availability of size-matched graft, thus avoiding inherent problems of allograft also provides a better economic option over endoprosthesis and its associated complications in select sites. The results can deteriorate over time that may require secondary reconstructive procedures like joint replacement.

LEVEL OF EVIDENCE

Level IV, Therapeutic Study.

Reconstruction of Bony Defects after Tumor Resection with 3D-Printed Anatomically Conforming Pelvic Prostheses through a Novel Treatment Strategy

There has been an increasing interest and enormous applications in three-dimensional (3D) printing technology and its prosthesis, driving many orthopaedic surgeons to solve the difficult problem of bony defects and explore new ways in surgery approach. However, the most urgent problem is without an effective prosthesis and standard treatment strategy. In order to resolve these problems, this study was performed to explore the use of a 3D-printed anatomically conforming pelvic prosthesis for bony defect reconstruction following tumor resection and to describe a detailed treatment flowchart and the selection of a surgical approach. Six patients aged 48-69 years who had undergone pelvic tumor resection underwent reconstruction using 3D-printed anatomically conforming pelvic prostheses according to individualized bony defects between March 2016 and June 2018. According to the Enneking and Dunham classification, two patients with region I+II tumor involvement underwent reconstruction using the pubic tubercle-anterior superior iliac spine approach and the lateral auxiliary approach and one patient with region II+III and three patients with region I+II+III tumor involvement underwent reconstruction using the pubic tubercle-posterior superior iliac spine approach. The diagnoses were chondrosarcoma and massive osteolysis. After a mean follow-up duration of 30.33 ± 9.89 months (range, 18-42), all patients were alive, without evidence of local recurrence or distant metastases. The average blood loss and blood transfusion volumes during surgery were 2500.00 ± 1461.51 ml (range, 1200-5000) and 2220.00 ± 1277.62 ml (range, 800-4080), respectively. During follow-up, the mean visual analogue scale (VAS) score decreased, and the mean Harris hip score increased. There were no signs of hip dislocation, prosthetic loosening, delayed wound healing, or periprosthetic infection. This preliminary study suggests the clinical effectiveness of 3D-printed anatomically conforming pelvic prostheses to reconstruct bony defects and provide anatomical support for pelvic organs. A new surgical approach that can be used to expose and facilitate the installation of 3D-printed prostheses and a new treatment strategy are presented. Further studies with a longer follow-up duration and larger sample size are needed to confirm these encouraging results.

Recent Developments of Biomaterials for Additive Manufacturing of Bone Scaffolds

Recent years have witnessed surging demand for bone repair/regeneration implants due to the increasing number of bone defects caused by trauma, cancer, infection, and arthritis worldwide. In addition to bone autografts and allografts, biomaterial substitutes have been widely used in clinical practice. Personalized implants with precise and personalized control of shape, porosity, composition, surface chemistry, and mechanical properties will greatly facilitate the regeneration of bone tissue and satiate the clinical needs. Additive manufacturing (AM) techniques, also known as 3D printing, are drawing fast growing attention in the fabrication of implants or scaffolding materials due to their capability of manufacturing complex and irregularly shaped scaffolds in repairing bone defects in clinical practice. This review aims to provide a comprehensive overview of recent progress in the development of materials and techniques used in the additive manufacturing of bone scaffolds. In addition, clinical application, pre-clinical trials and future prospects of AM based bone implants are also summarized and discussed.

A 3D-CT Analysis of Femoral Symmetry-Surgical Implications

BACKGROUND

Mirroring the image of the affected side is a widely used technique for surgical planning in orthopedic surgery, especially for fractures and custom-made prostheses. Our objective is to evaluate the three-dimensional symmetry of the femurs using finite element analysis and manual alignment.

METHODS

Using the computed tomography of 15 patients without lower limb pathology, 30 3D biomodels of their femurs were obtained. The error obtained through image manipulation was calculated and broken down into a rendering error and a manual overlay error. The Hausdorff-Besicovitch method was applied to obtain the total asymmetry. The manipulation error was theb subtracted from it to obtain the intrapersonal asymmetry.

RESULTS

The mean intrapersonal asymmetry was 0.93 mm. It was obtained by subtracting the error derived from rendering and alignment of 0.59 mm (SD 0.17 mm) from the overall mean error of 1.52 mm (SD 1.45).

CONCLUSIONS

Intrapersonal femoral asymmetry is low enough to use the mirror image of the healthy side as a reference for three-dimensional surgical planning. This type of planning is especially useful in deformity surgery when the objective of the surgery is not to restore only one specific parameter but to obtain a general functional morphology when a healthy contralateral femur is available.

What are the Complications of Three-dimensionally Printed, Custom-made, Integrative Hemipelvic Endoprostheses in Patients with Primary Malignancies Involving the Acetabulum, and What is the Function of These Patients?

BACKGROUND

Functional reconstruction after resection of pelvic malignancies involving the acetabulum remains challenging. Numerous reconstruction methods have been proposed, but they are generally associated with mechanical and nonmechanical complications. To improve the function of patients with primary malignancies of the acetabulum after internal hemipelvectomy and reduce the complication rate after this procedure, we designed a series of three-dimensionally (3D) printed, custom-made, integrative hemipelvic endoprostheses with a porous structure and wanted to present the early results of using this construct to determine whether it could be considered a reasonable reconstruction option.

QUESTIONS/PURPOSES

We performed this study to (1) evaluate, in a small group of patients, whether the new endoprosthesis restores short-term lower-limb function; (2) identify short-term complications associated with the use of this endoprosthesis; and (3) assess osseointegration between the host bone and the 3D-printed integrative hemipelvic endoprosthesis with a porous structure.

METHODS

Between October 2016 and May 2017, our center treated 26 patients with malignancies involving the acetabulum. Thirteen of these patients received hemipelvic replacement with a 3D-printed, custom-made, integrative endoprosthesis, six received hemipelvic replacement with a modular endoprosthesis, four received radiotherapy, and three received external hemipelvectomy. Resection and reconstruction with a 3D-printed, custom-made, integrative endoprosthesis were indicated if the resection margin was the same as that achieved in hemipelvectomy, if reconstruction would preserve reasonable function after resection, if the patient had a good physical status and life expectancy longer than 6 months, and if the patient was willing to accept the potential risk of a 3D-printed, custom-made, endoprosthesis. The exclusion criteria were an inability to achieve a satisfactory surgical margin with limb salvage, inability to preserve the function of the limb because of tumor involvement of the sacral nerve or sciatic nerve, and unresectable and/or widely metastatic disease on presentation. Pain and function were evaluated with the 10-cm VAS score (range 0 to 10; a lower score is desirable), the 1993 version of the Musculoskeletal Tumor Society (MSTS-93) score (range 0 to 30; a higher score is desirable), and the Harris hip score ([HHS]; range 0 to 100; a higher score is desirable) were evaluated preoperatively and at a median of 27 months after reconstruction (range 24 to 31 months). The functional scores and complications were recorded after reviewing the patients' records. Osseointegration was assessed with digital tomosynthesis by two senior surgeons. We observed the trabecular structures connected to the implant surface to assess whether there was good osseointegration.

RESULTS

The median preoperative VAS score, MSTS-93 score, and HHS were 5 (range 2 to 8), 14 (range 3 to 18), and 64 (range 20 to 76) points, respectively. At the latest follow-up interval, the median VAS score, MSTS-93 score, and HHS were 2 (range 0 to 6), 23 (range 15 to 27), and 82 (range 44 to 93) points, respectively. No deep infection, dislocation, endoprosthetic breakage, aseptic loosening, or local recurrence occurred. Two patients experienced delayed wound healing; the wounds healed after débridement. Using digital tomography, we found that all implants were well-osseointegrated at the final follow-up examination.

CONCLUSIONS

A 3D-printed, custom-made, integrative hemipelvic endoprosthesis provides acceptable early outcomes in patients undergoing pelvic reconstruction. Osseointegration is possible, and we anticipate this will lead to biologic stability with a longer follow-up interval. The custom-made integrative design ensured precise implantation. Although a few patients in this study had only a short follow-up duration, the functional results were reasonable. We have observed no major complications so far, but this was a very small series and we caution that these are large reconstructions that will certainly result in complications for some patients. Our method uses a precise preoperative simulation and endoprosthesis design to aid the surgeon in performing challenging operations. If our early results are confirmed with more patients and longer follow-up and are replicated at other centers, this may be a reconstruction option for patients with periacetabular malignancies.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Three-dimensional-printed customized prosthesis for pubic defect: prosthesis design and surgical techniques

Background

This study is to describe the detailed design and surgical techniques of three-dimensional (3D)-printed customized prosthesis for pubic bone defect.

Patients and methods

Five patients under type III resections were included in this study. Based on radiography data, 3D pelvic model was established and virtual surgery was simulated. Detailed anatomy data were measured including the size and arc of normal pubis, the size of residual bone in acetabular side. Different fixation ways were considered according to shape of defect. After features modification and porous structure design, prostheses were fabricated. The osteotomy guides and plastic models were used during surgery.

Result

Of 5 cases, the prostheses consist of the type with stem (3, 60%) and the type without stem (2, 40%). Mean follow-up period was 13.6 months (range, 8-24 months). For partial pubis removed cases, the mean length and width of narrowest part of normal superior pubis were 13.19 mm (range, 12.51-14.12 mm) and 7.80 mm (range, 7.18-8.26 mm) respectively. Mean arc of normal pubis was 2.71 rad (range, 2.66-2.73 rad). For the entire pubis resection cases, the mean diameter of narrowest parts and length of normal superior pubis were 11.52 mm (range, 11.13-11.91 mm) and 64.78 mm (range, 63.46-66.09 mm), while the diameter of narrowest part and length of normal inferior pubis were 7.37 mm (range, 7.20-7.54 mm) and 86.43 mm (range, 84.28-88.57 mm). Mean length and arc of intramedullary stem was 20 mm (range, 18-21 mm) and 2.7 rad. Mean screw holes number was 6.3 (range, 6-7) while ultimate screws number in surgeries was 4.3 (range, 4-5). Porous structure with 600-μm-pore size and 70% porosity was applied in parts of contact with residual bone.

Conclusion

3D-printed customized prostheses could be a feasible option to reconstruct bone defect after type III resection. The design of 3D-printed customized prostheses is a multi-step process which is based on strict anatomic measurement.

A composite hydrogel-3D printed thermoplast osteochondral anchor as example for a zonal approach to cartilage repair: in vivo performance in a long-term equine model

Recent research has been focusing on the generation of living personalized osteochondral constructs for joint repair. Native articular cartilage has a zonal structure, which is not reflected in current constructs and which may be a cause of the frequent failure of these repair attempts. Therefore, we investigated the performance of a composite implant that further reflects the zonal distribution of cellular component both in vitro and in vivo in a long-term equine model. Constructs constituted of a 3D-printed poly(ϵ-caprolactone) (PCL) bone anchor from which reinforcing fibers protruded into the chondral part of the construct over which two layers of a thiol-ene cross-linkable hyaluronic acid/poly(glycidol) hybrid hydrogel (HA-SH/P(AGE-co-G)) were fabricated. The top layer contained Articular Cartilage Progenitor Cells (ACPCs) derived from the superficial layer of native cartilage tissue, the bottom layer contained mesenchymal stromal cells (MSCs). The chondral part of control constructs were homogeneously filled with MSCs. After six months in vivo, microtomography revealed significant bone growth into the anchor. Histologically, there was only limited production of cartilage-like tissue (despite persistency of hydrogel) both in zonal and non-zonal constructs. There were no differences in histological scoring; however, the repair tissue was significantly stiffer in defects repaired with zonal constructs. The sub-optimal quality of the repair tissue may be related to several factors, including early loss of implanted cells, or inappropriate degradation rate of the hydrogel. Nonetheless, this approach may be promising and research into further tailoring of biomaterials and of construct characteristics seems warranted.

Long-term outcome of iliosacral resection without reconstruction for primary bone tumours

AIMS

Iliac wing (Type I) and iliosacral (Type I/IV) pelvic resections for a primary bone tumour create a large segmental defect in the pelvic ring. The management of this defect is controversial as the surgeon may choose to reconstruct it or not. When no reconstruction is undertaken, the residual ilium collapses back onto the remaining sacrum forming an iliosacral pseudarthrosis. The aim of this study was to evaluate the long-term oncological outcome, complications, and functional outcome after pelvic resection without reconstruction.

METHODS

Between 1989 and 2015, 32 patients underwent a Type I or Type I/IV pelvic resection without reconstruction for a primary bone tumour. There were 21 men and 11 women with a mean age of 35 years (15 to 85). The most common diagnosis was chondrosarcoma (50%, n = 16). Local recurrence-free, metastasis-free, and overall survival were assessed using the Kaplan-Meier method. Patient function was evaluated using the Musculoskeletal Tumour Society (MSTS) and Toronto Extremity Salvage Score (TESS).

RESULTS

At a mean follow-up of 159 months (1 to 207), 23 patients were alive without disease, one was alive with lung metastases, one was alive following local recurrence, four were dead of disease, and three had died from other causes. The overall ten-year survival was 77%. There was only one (3%) local recurrence, which occurred at 26 months. There were 18 complications in 17 patients; 13 wound healing complications/infections, three fractures, one pulmonary embolism, and one dislocation of the hip. Most complications occurred early. The mean functional scores were 21.1 (SD 8.1) for MSTS-87, 67.3 (SD 23.9) for MSTS-93 and 76.2 (SD 20.6) for TESS.

CONCLUSION

Patients requiring Type I or Type I/IV pelvic resections can expect a good oncological outcome and a high rate of local control. Complications are generally acute in nature and are easily manageable. These patients achieved a good functional outcome without the need for bony reconstruction. Cite this article: Bone Joint J 2020;102-B(6):779-787.

Varisized 3D-Printed Lunate for Kienböck's Disease in Different Stages: Preliminary Results

OBJECTIVE

To evaluate the feasibility of arthroplasty with varisized three-dimensional(3D) printing lunate prosthesis for the treatment of advanced Kienböck's disease (KD).

METHODS

From 2016 November to 2018 September, a retrospective study was performed for the patients of KD in our hospital. Five patients (two males, three females) were included in this study. The mean age of the patients at the time of surgery was 51.6 years (range, 37-64 years). Varisized prosthesis identical to the live model in a ratio of 1:0.85, 1:1, and 1:1.1 were fabricated by 3D printing. All patients (one in Lichtman IIIA stage, two in Lichtman IIIB stage, one in Lichtman IIIC stage, and one in Lichtman IV stage) were treated with lunate excision and 3D printing prosthetic arthroplasty. Visual analog scale score (VAS), the active movement of wrist (extension, flexion) and strength were assessed preoperatively and postoperatively. The Mayo Modified Wrist Score (MMWS), Disabilities of the Arm, Shoulder and Hand (DASH) Score, and patient's satisfaction were evaluated during the follow-up.

RESULTS

Prosthesis identical to the live model in a ratio of 1:0.85 or 1:1 were chosen for arthroplasty. The mean operation time (range, 45 to 56 min) was 51.8 ± 4.44 min. Follow-up time ranged from 11 months to 33 months with the mean value of 19.4 months. The mean extension range of the wrist significantly increased from preoperative 44° ± 9.6° to postoperative 60° ± 3.5° (P < 0.05). The mean flexion range of the wrist significantly increased from preoperative 40° ± 10.6° to postoperative 51° ± 6.5° (P < 0.05). The active movement of wrist and strength were improved significantly in all patients. VAS was significantly reduced from 7.3 preoperatively to 0.2 at the follow-up visit (P < 0.05). The mean DASH score was 10 (range, 7.2-14.2), and the mean MMWS was 79 (range, 70-90). There were no incision infection. All patients were satisfied with the treatment.

CONCLUSIONS

For patients suffering advanced Kienböck's disease, lunate excision followed by 3D printing prosthetic arthroplasty can reconstruct the anatomical structure of the carpal tunnel, alleviate pain, and improve wrist movement.

Development of AM Technologies for Metals in the Sector of Medical Implants

Additive manufacturing (AM) processes have undergone significant progress in recent years, having been implemented in sectors as diverse as automotive, aerospace, electrical component manufacturing, etc. In the medical sector, different devices are printed, such as implants, surgical guides, scaffolds, tissue engineering, etc. Although nowadays some implants are made of plastics or ceramics, metals have been traditionally employed in their manufacture. However, metallic implants obtained by traditional methods such as machining have the drawbacks that they are manufactured in standard sizes, and that it is difficult to obtain porous structures that favor fixation of the prostheses by means of osseointegration. The present paper presents an overview of the use of AM technologies to manufacture metallic implants. First, the different technologies used for metals are presented, focusing on the main advantages and drawbacks of each one of them. Considered technologies are binder jetting (BJ), selective laser melting (SLM), electron beam melting (EBM), direct energy deposition (DED), and material extrusion by fused filament fabrication (FFF) with metal filled polymers. Then, different metals used in the medical sector are listed, and their properties are summarized, with the focus on Ti and CoCr alloys. They are divided into two groups, namely ferrous and non-ferrous alloys. Finally, the state-of-art about the manufacture of metallic implants with AM technologies is summarized. The present paper will help to explain the latest progress in the application of AM processes to the manufacture of implants.

Biomechanics study of a 3D printed sacroiliac joint fixed modular hemipelvic endoprosthesis

BACKGROUND

Reconstructing pelvic type II + III defect caused by bone tumors is challenging. The purpose of this study was to explore the in vitro biomechanical properties of a reconstructed pelvis after periacetabular resection using three-dimensional (3D) printed sacroiliac joint (SIJ) fixed modular hemipelvic endoprosthesis.

METHODS

Type II/II + III pelvic resection was simulated on an artificial pelvic model. The bilateral acetabulum and pubis were constrained, and the pelvis was maintained in a human physiological standing position. A vertically continuous linear load was applied on the upper face of S1 until obvious unloading or fixed failure occurred. A noncontact optical 3D strain measuring system was used to measure the strains and displacements at the selected area.

FINDINGS

The strain at the points of interest did not obviously differ between the intact and reconstructed pelvis models. The difference in the displacement on the reconstructed side was 0.237 mm, and that on the contralateral side was 0.245 mm. The maximum differences in the displacement at the acetabulum were 0.209 mm (vertical) and 0.324 mm (horizontal). A crack at the superior rim of the contralateral acetabulum occurred, and failure loading of 7.126 kN.

INTERPRETATION

The prosthesis in this study showed satisfactory mechanical properties and structural stability. According to the mechanical evaluations, the 3D printed sacroiliac-stabilized hemipelvic endoprosthesis can be used to reconstruct a stable acetabular structure, and there was little influence on the mechanical properties of the surrounding bone structures. The prosthesis design is reasonable, and the mechanical distribution on the reconstructed side was similar to that on the contralateral side.

Analysis of principles inspiring design of three-dimensional-printed custom-made prostheses in two referral centres

BACKGROUND

Three-dimensional (3D) printing is an emerging technology used in numerous medical fields. Reconstruction of large bone defects after tumor resections or complex revision surgeries is challenging especially in specific sites where modular prostheses are not available. The possibility to realize custom-made 3D-printed prostheses improves their application in surgical field despite the complication rate, gaining a lot of attention for potential benefits.

OBJECTIVES

We asked: (1) What are the emerging indications and designs of 3D-printed prostheses for complex bone reconstructions? (2) What complications occur with the use of custom implants considering site?

STUDY DESIGN AND METHODS

We performed a retrospective analysis of every patient in whom a custom-made 3D-printed prosthesis was used to reconstruct a bone defect after resection for a bone tumour or challenging revision surgery from 2009 to 2018 in two referral centres. Forty-one patients (11 males [27%], 30 females [73%]) with a mean age of 41 years (range, 10-78 years) were included. Our general indications for using these implants were complex reconstructions of massive bone defects, in the absence of available modular prostheses. Seven were non-oncologic patients, whereas 24 patients were mainly treated for their malignant bone tumours. Custom-made 3D-printed prostheses were used in pelvis (29), forearm (6), scapula (2), distal tibia (2), calcaneus (1), and femoral diaphysis (1). The reconstruction included complete articular replacement in 24 cases (58%) whereas a combined spinopelvic implant has been used in two cases. Flaps were used in 25 cases (61%). Statistical analyses include Kaplan-Meier curves of survival.

RESULTS

The mean follow-up was 20 months. In the oncologic group, overall survival was 89% at five year follow-up and only three patients died of disease. Only one patient required implant removal due to deep infection. Overall major and minor complication rate was 22% (14 complications in 9/41 patients), mainly wound-related problems. One patient reported a periprosthetic fracture, one had hip dislocation, and four (12% [4/34 cases]) had local recurrence. Mean MSTS functional outcome score at follow-up was 73% (range, 23-100%), with a full weight bearing at an average time of 73 days from surgery of lower limbs.

CONCLUSIONS

Custom-made 3D-printed prostheses represent at today a promising reconstructive technique, maintaining however the correct indications for their use in musculoskeletal oncology and challenging revision surgery. Complication rate is acceptable, with infection and wound healing problems relatively common after complex pelvic reconstructions. We will continue to follow our patients over the longer term to ascertain the role of these implants; however, larger studies will need to confirm indications and control for prognostic factors.