Oncological and surgical outcome after treatment of pelvic sarcomas

A pictographic guide for decision making in surgery for pelvic bone sarcoma

Pelvic bone sarcoma surgery is challenging due to complex anatomy, proximity to major neurovascular structures, and, more importantly, the potential for complications. Decision-making is vital in offering patients the best oncological and functional outcomes after surgery. Multidisciplinary teams involved from the stage of diagnosis and treatment planning, followed by surgery by experienced teams have proven to be beneficial. Tumour-free margin clearance is essential, and surgical planning must be tailored to achieve the same. The choice of reconstruction needs to be decided based on the amount of bone resected and the available expertise and resources. Lesions isolated only to PI or PIII region may not need reconstruction. Though pedestal cups and Custom-made prosthesis are useful in reconstruction after periacetabular tumour resections, hip transposition surgery is also widely practiced by surgeons with favourable outcomes particularly after neo-adjuvant radiotherapy/proton beam therapy. Navigation has shown promise in achieving tumour-negative margins and disease-free progression particularly in chondrosarcoma. A flap-based approach can be considered for hindquarter amputations; however, patients need to be counseled regarding the complications following this surgery. This article, with proposed flowcharts, is aimed at providing practicing surgeons with a guide toward decision-making while planning pelvic bone sarcoma surgery.

Developmental Patterns and Risk Factors of Scoliosis After Hemipelvectomy for the Pelvic Bone Tumor

BACKGROUND

Postoperative scoliosis is often seen after hemipelvectomy for malignancies involving the pelvic area, but the details remain unclear. The objectives were to investigate the development patterns and risk factors of scoliosis after hemipelvectomy.

METHODS

We retrospectively reviewed 30 patients who underwent hemipelvectomy at our hospital between 1998 and 2020. The risk factors of scoliosis with a Cobb angle of ≥10° were investigated.

RESULTS

The postoperative Cobb angle significantly increased in all patients compared with the preoperative one (p < 0.001), and the change ratio of the Cobb angle was significantly higher during the first postoperative year than thereafter. The external hemipelvectomy (EH) group demonstrated a larger Cobb angle and a higher change ratio than the internal hemipelvectomy group. Nine patients developed scoliosis with a final Cobb angle of ≥10°, and the risk factors were EH (p = 0.017), P1+2+3+4 resection according to the Enneking classification (p = 0.005), iliac crest resection (p = 0.004), L5/S resection (p = 0.020), and no pelvic ring reconstruction after hemipelvectomy (p = 0.004).

CONCLUSIONS

Approximately 30% of patients who underwent hemipelvectomy developed scoliosis with a Cobb angle of ≥10°, and this angle increased rapidly during the first postoperative year. Hence, careful follow-up of scoliosis is required after hemipelvectomy.

Composite Reconstruction With Irradiated Autograft Plus Total Hip Replacement After Type II Pelvic Resections for Tumors Is Feasible but Fraught With Complications

BACKGROUND

Malignancies involving the pelvic ring present numerous challenges, especially in the periacetabular area. Extensive resection of the pelvic region without reconstruction can lead to severe functional impairment. Numerous reconstructive options exist, but all have drawbacks. Extracorporeally irradiated autografts are one option for reconstruction after periacetabular resections; they offer the potential advantages of eliminating the risk of allogeneic reactions associated with allografts and preserving local anatomy. However, little is known about the durability and risks of this approach in pelvic reconstruction.

QUESTIONS/PURPOSES

(1) What are the survival rates of the autograft used, and if there is graft loss, what is the extent of this loss? (2) What are the functional outcomes after the implementation of this method? (3) What is the rate and nature of complications associated with this approach?

METHODS

This is a retrospective case series from one subspecialty tumor unit that evaluated patients treated between January 2005 to January 2022. During that time, three surgeons treated 48 patients with Type II resections (defined as resection of periacetabular area). Patients treated with isolated Type II resections were eligible, as were those treated either with Type I+II resections, Type II+III resections, Type I+II+III resections, and Type I+II+III+IV resections. Of those, 21% (10 of 48) were treated primarily with a cone prosthesis, 13% (6 of 48) were treated without femoral reconstruction, 10% (5 of 48) were treated with resection without reconstruction, and 6% (3 of 48) had a THA on the sacrum, leaving 50% (24 of 48) of patients who were treated with femoral and acetabular reconstruction using extracorporeally irradiated autograft and total hip replacement; those patients were potentially eligible for this study. During that time span, we used this approach in all Type II pelvic resection procedures, when a part of the hemipelvis could be preserved without resection (other than Type I+II+III+IV) and where we predicted that there would be sufficient bone stock after tumor removal. Of those, 21% (5 of 24) were lost to follow-up before 2 years, and 13% (3 of 24) died within 2 years with the reconstruction intact and without any reoperation or graft loss, leaving 67% (16 of 24) for analysis here. Demographic characteristics, type of tumor, tumor origin site, type of applied resection, and extent of applied surgical procedure were noted. Of 16 patients, 12 were male, with a mean age of 38 ± 21 years. Tumor types included chondrosarcoma in eight patients, malignant mesenchymal tumor in four patients, osteosarcoma in two patients, and Ewing sarcoma in two patients. Among these, 10 patients had tumors originating from the pelvis, whereas six patients had tumors originating from the proximal femur. We used a Kaplan-Meier estimator to calculate survivorship free from total or partial graft removal at 72 months. To measure functional results, the Musculoskeletal Tumor Society (MSTS) scoring system was utilized at most recent follow-up so as to be able to evaluate the impact of complications (if any) on the ultimate result. The MSTS score ranges from a minimum of 0 points to a maximum of 30 points, where a higher score reflects lower pain and higher functional and emotional capacity. Related complications, time of complications, secondary interventions, and mortality rates were also ascertained from chart review.

RESULTS

Graft survival rate at 72 months after initial reconstruction, free from partial or total graft removal, was 50% (95% CI 26% to 75%). Kaplan-Meier analyses revealed estimated mean time of graft removal as 43 months (95% CI 28 to 58). The graft was protected in eight patients on their final follow-up radiographs. The median (range) MSTS score was 18 (6 to 25) of 30 points at most-recent follow-up (these scores include patients who have had their grafts removed). In all, 15 of 16 patients had 17 complications; 16 were major complications (defined as those substantial enough to result in further surgery or a life- or limb-threatening event). A total of 14 of those 15 patients underwent one or more secondary procedures (a total of 21 unplanned additional procedures were performed in those patients). Deep infection was the most common complication, occurring in eight patients. Prosthesis dislocation occurred in four patients. Three patients developed aseptic acetabular component loosening, two had graft fractures, and one patient developed heterotopic ossification.

CONCLUSION

Composite reconstruction with extracorporeal irradiated autografts plus total hip replacement is a feasible reconstruction technique after Type II pelvic resections, although complications and reoperations were common. Although no reconstruction technique has been proven superior to other alternatives, the high risk of complications and reoperations associated with this technique should be considered when selecting from among possible alternative reconstruction methods.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Obesity increases the risk of major wound complications following pelvic resection for bone sarcoma

BACKGROUND

Given the paucity of data, the objective of this study is to evaluate the association between obesity and major wound complications following pelvic bone sarcoma surgery specifically.

METHODS

Patients who underwent pelvic resection for bone sarcoma from 2005 to 2021 with a minimum 6-month follow-up were reviewed. Patients with benign tumors, primary soft tissue sarcomas, local recurrence at presentation, pelvic metastatic disease, and underweight patients were excluded. A major wound complication was defined as the need for a secondary debridement procedure. Differences in baseline demographics, surgical factors, postoperative complications, and functional outcomes were compared between obese and nonobese patients. A multivariate logistic regression was performed to identify independent risk factors for major wound complications, and a Kaplan-Meier analysis to estimate overall survival between both groups.

RESULTS

Of the 93 included patients, 21 were obese (body mass index ≥ 30 kg/m2). The obesity group had a significantly higher rate of major wound complication (52% vs. 26%, p = 0.034) and a lower Toronto Extremity Salvage Score at 1-year postoperatively (47.5 vs. 71.4, p = 0.025). Obesity was the only independent risk factor in the multivariate analysis. No differences in overall survival were demonstrated between groups.

CONCLUSIONS

Obesity is a significant risk factor for major wound complications in pelvic bone sarcoma treatment. This highlights the importance of careful perioperative optimization and wound management.

Changes in walking function and neural control following pelvic cancer surgery with reconstruction

Introduction: Surgical planning and custom prosthesis design for pelvic cancer patients are challenging due to the unique clinical characteristics of each patient and the significant amount of pelvic bone and hip musculature often removed. Limb-sparing internal hemipelvectomy surgery with custom prosthesis reconstruction has become a viable option for this patient population. However, little is known about how post-surgery walking function and neural control change from pre-surgery conditions. Methods: This case study combined comprehensive walking data (video motion capture, ground reaction, and electromyography) with personalized neuromusculoskeletal computer models to provide a thorough assessment of pre- to post-surgery changes in walking function (ground reactions, joint motions, and joint moments) and neural control (muscle synergies) for a single pelvic sarcoma patient who received internal hemipelvectomy surgery with custom prosthesis reconstruction. Pre- and post-surgery walking function and neural control were quantified using pre- and post-surgery neuromusculoskeletal models, respectively, whose pelvic anatomy, joint functional axes, muscle-tendon properties, and muscle synergy controls were personalized using the participant's pre-and post-surgery walking and imaging data. For the post-surgery model, virtual surgery was performed to emulate the implemented surgical decisions, including removal of hip muscles and implantation of a custom prosthesis with total hip replacement. Results: The participant's post-surgery walking function was marked by a slower self-selected walking speed coupled with several compensatory mechanisms necessitated by lost or impaired hip muscle function, while the participant's post-surgery neural control demonstrated a dramatic change in coordination strategy (as evidenced by modified time-invariant synergy vectors) with little change in recruitment timing (as evidenced by conserved time-varying synergy activations). Furthermore, the participant's post-surgery muscle activations were fitted accurately using his pre-surgery synergy activations but fitted poorly using his pre-surgery synergy vectors. Discussion: These results provide valuable information about which aspects of post-surgery walking function could potentially be improved through modifications to surgical decisions, custom prosthesis design, or rehabilitation protocol, as well as how computational simulations could be formulated to predict post-surgery walking function reliably given a patient's pre-surgery walking data and the planned surgical decisions and custom prosthesis design.

Custom three-dimensional printed implants for reconstruction of oncologic pelvic defects

The use of three-dimensional printed implants in the field of orthopedic surgery has become increasingly popular and has potentiated hip reconstruction in the setting of oncologic resections of the pelvis and acetabulum. In this review, we examine and discuss the indications and technical considerations for custom implant reconstruction of pelvic defects.

Stress-shielding resistant design of custom pelvic prostheses using lattice-based topology optimization

Endoprosthetic reconstruction of the pelvic bone using 3D-printed, custom-made implants has delivered early load-bearing ability and good functional outcomes in the short term to individuals with pelvic sarcoma. However, excessive stress-shielding and subsequent resorption of peri‑prosthetic bone can imperil the long-term stability of such implants. To evaluate the stress-shielding performance of pelvic prostheses, we developed a sequential modeling scheme using subject-specific finite element models of the pelvic bone-implant complex and personalized neuromusculoskeletal models for pre- and post-surgery walking. A new topology optimization approach is introduced for the stress-shielding resistant (SSR) design of custom pelvic prostheses, which uses 3D-printable porous lattice structures. The SSR optimization was applied to a typical pelvic prosthesis to reconstruct a type II+III bone resection. The stress-shielding performance of the optimized implant based on the SSR approach was compared against the conventional optimization. The volume of the peri‑prosthetic bone predicted to undergo resorption post-surgery decreased from 44 to 18%. This improvement in stress-shielding resistance was achieved without compromising the structural integrity of the prosthesis. The SSR design approach has the potential to improve the long-term stability of custom-made pelvic prostheses.

Iliofemoral Arthrodesis as a Reconstructive Surgical Technique in the Management of Malignant Periacetabular Tumors: Case Series

Introduction

Reconstructive options for surgical malignant of periacetabular tumors include endoprosthetic reconstructions, biologic reconstruction, hip transposition, hip rotationplasty, and iliofemoral arthrodesis. In this case series, we discuss the outcome of iliofemoral arthrodesis as a reconstruction option in the management of malignant periacetabular tumors.

Case Report

A 45-year-old woman with complaints of right hip pain for 4-year duration was evaluated to have a well-defined radiolucent osteolytic lesion with calcifications localized around the right acetabulum diagnosed to be chondrosarcoma later on. Another 44-year-old woman with complaints of left hip pain for 2-year duration was evaluated to have fibrosarcoma of left gluteus maximus, piriformis, and gemelli extending to quadratus femoris. Wide resection was planned for both patients, and iliofemoral arthrodesis was performed. Both patients did not receive any adjuvant treatment. Both the patients demonstrated good functional outcomes at 2-years follow-up without any recurrence or distant metastasis.

Conclusion

Iliofemoral arthrodesis serves as a cost-effective reconstructive option in the management of malignant periacetabular tumors. Meticulous dissection and wide resection remain key to preventing recurrence or complications.

An overview of 3D printed metal implants in orthopedic applications: Present and future perspectives

With the ability to produce components with complex and precise structures, additive manufacturing or 3D printing techniques are now widely applied in both industry and consumer markets. The emergence of tissue engineering has facilitated the application of 3D printing in the field of biomedical implants. 3D printed implants with proper structural design can not only eliminate the stress shielding effect but also improve in vivo biocompatibility and functionality. By combining medical images derived from technologies such as X-ray scanning, CT, MRI, or ultrasonic scanning, 3D printing can be used to create patient-specific implants with almost the same anatomical structures as the injured tissues. Numerous clinical trials have already been conducted with customized implants. However, the limited availability of raw materials for printing and a lack of guidance from related regulations or laws may impede the development of 3D printing in medical implants. This review provides information on the current state of 3D printing techniques in orthopedic implant applications. The current challenges and future perspectives are also included.

[Primary malignant bone tumors]

Primary malignant bone tumors are rare. Due to an associated worsening of the prognosis by diagnostic delay, these tumors must not be overlooked in the routine clinical practice and should therefore always be included in the differential diagnosis for the clarification of musculoskeletal complaints. A correct interpretation of the diagnostic procedure, radiological investigations and a biopsy of doubtful lesions can confirm the diagnosis. Osteosarcoma, chondrosarcoma and Ewing's sarcoma are the three most frequent primary malignant bone tumors and other entities occur only sporadically. While the prognosis of osteosarcoma and Ewing's sarcoma has been vastly improved with chemotherapy, chondrosarcomas mostly respond only poorly or not at all to systemic chemotherapy. Wide resection represents the gold standard in the surgical management of all primary malignant bone tumors. In addition, Ewing's sarcoma responds well to irradiation. The multidisciplinary management of primary malignant bone tumors should be performed at dedicated and specialized centers.

Trajectory of worst pain within the first two weeks following pelvic and sacral tumor surgery and long-term outcome: a pilot observational prospective cohort study

BACKGROUND

Pain management after pelvic and sacral tumor surgery is challenging and requires a multidisciplinary and multimodal approach. Few data on postoperative pain trajectories have been reported after pelvic and sacral tumor surgery. The aim of this pilot study was to determine pain trajectories within the first 2 weeks after surgery and explore the impact on long-term pain outcomes.

METHODS

Patients scheduled for pelvic and sacral tumor surgery were prospectively recruited. Worst/average pain scores were evaluated postoperatively using questions adapted from the Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R) until pain resolution was reached or up to 6 months after surgery. Pain trajectories over the first 2 weeks were compared using the k-means clustering algorithm. Whether pain trajectories were associated with long-term pain resolution and opioid cessation was assessed using Cox regression analysis.

RESULTS

A total of 59 patients were included. Two distinct groups of trajectories for worst and average pain scores over the first 2 weeks were generated. The median pain duration in the high vs low pain group was 120.0 (95% CI [25.0, 215.0]) days vs 60.0 (95% CI [38.6, 81.4]) days (log rank p = 0.037). The median time to opioid cessation in the high vs low pain group was 60.0 (95% CI [30.0, 90.0]) days vs 7.0 (95% CI [4.7, 9.3]) days (log rank p < 0.001). After adjusting for patient and surgical factors, the high pain group was independently associated with prolonged opioid cessation (hazard ratio [HR] 2.423, 95% CI [1.254, 4.681], p = 0.008) but not pain resolution (HR 1.557, 95% CI [0.748, 3.243], p = 0.237).

CONCLUSIONS

Postoperative pain is a significant problem among patients undergoing pelvic and sacral tumor surgery. High pain trajectories during the first 2 weeks after surgery were associated with delayed opioid cessation. Research is needed to explore interventions targeting pain trajectories and long-term pain outcomes.

TRIAL REGISTRATION

The trial was registered at ClinicalTrials.gov ( NCT03926858 , 25/04/2019).

Finite element analysis of screw fixation durability under multiple boundary and loading conditions for a custom pelvic implant

Despite showing promising functional outcomes for pelvic reconstruction after sarcoma resection, custom-made pelvic implants continue to exhibit high complication rates due to fixation failures. Patient-specific finite element models have been utilized by researchers to evaluate implant durability. However, the effect of assumed boundary and loading conditions on failure analysis results of fixation screws remains unknown. In this study, the postoperative stress distributions in the fixation screws of a state-of-the-art custom-made pelvic implant were simulated, and the risk of failure was estimated under various combinations of two bone-implant interaction models (tied vs. frictional contact) and four load cases from level-ground walking and stair activities. The study found that the average weighted peak von Mises stress could increase by 22-fold when the bone-implant interactions were modeled with a frictional contact model instead of a tied model, and the likelihood of fatigue and pullout failure for each screw could change dramatically when different combinations of boundary and loading conditions were used. The inclusion of additional boundary and loading conditions led to a more reliable analysis of fixation durability. These findings demonstrated the importance of simulating multiple boundary conditions and load cases for comprehensive implant design evaluation using finite element analysis.

A computational method for estimating trunk muscle activations during gait using lower extremity muscle synergies

One of the surgical treatments for pelvic sarcoma is the restoration of hip function with a custom pelvic prosthesis after cancerous tumor removal. The orthopedic oncologist and orthopedic implant company must make numerous often subjective decisions regarding the design of the pelvic surgery and custom pelvic prosthesis. Using personalized musculoskeletal computer models to predict post-surgery walking function and custom pelvic prosthesis loading is an emerging method for making surgical and custom prosthesis design decisions in a more objective manner. Such predictions would necessitate the estimation of forces generated by muscles spanning the lower trunk and all joints of the lower extremities. However, estimating trunk and leg muscle forces simultaneously during walking based on electromyography (EMG) data remains challenging due to the limited number of EMG channels typically used for measurement of leg muscle activity. This study developed a computational method for estimating unmeasured trunk muscle activations during walking using lower extremity muscle synergies. To facilitate the calibration of an EMG-driven model and the estimation of leg muscle activations, EMG data were collected from each leg. Using non-negative matrix factorization, muscle synergies were extracted from activations of leg muscles. On the basis of previous studies, it was hypothesized that the time-varying synergy activations were shared between the trunk and leg muscles. The synergy weights required to reconstruct the trunk muscle activations were determined through optimization. The accuracy of the synergy-based method was dependent on the number of synergies and optimization formulation. With seven synergies and an increased level of activation minimization, the estimated activations of the erector spinae were strongly correlated with their measured activity. This study created a custom full-body model by combining two existing musculoskeletal models. The model was further modified and heavily personalized to represent various aspects of the pelvic sarcoma patient, all of which contributed to the estimation of trunk muscle activations. This proposed method can facilitate the prediction of post-surgery walking function and pelvic prosthesis loading, as well as provide objective evaluations for surgical and prosthesis design decisions.

Delayed femoral vein ligation reduces operative time and blood loss during hip disarticulation in patients with extremity tumors

This study aimed to evaluate the effects of delayed femoral vein ligation on the clinical outcomes of hip disarticulation. We retrospectively reviewed 20 patients with extremity tumors (10 bone tumors and 10 soft tissue sarcomas [STS]) who underwent hip disarticulation. Patients treated for hip disarticulation with synchronous femoral vein ligation (n = 10, regular surgery group) and hip disarticulation with delayed femoral vein ligation (n = 10, delayed ligation group), respectively, were enrolled in this study. The operative time and blood loss were used to evaluate the clinical outcomes. The delayed ligation group had significantly lower operative times than the regular surgery group (P < 0.05). Total, hidden, and intraoperative blood loss were all significantly lower in the delayed ligation group than in the regular surgery group (P < 0.05). However, there were no significant differences in postoperative blood loss. In conclusion, delayed femoral vein ligation could significantly reduce the operative time, hidden blood loss, and intraoperative blood loss in patients undergoing hip disarticulation.

Management of pelvic sarcoma

Pelvic sarcomas are a rare and heterogenous group of tumors divided into two groups: soft tissue sarcomas and bone sarcomas. Soft tissue sarcomas of the pelvis include most commonly liposarcoma, leiomyosarcoma, gastrointestinal stromal tumors, malignant peripheral nerve sheath tumors, and solitary fibrous tumors. Bone sarcomas of the pelvis most commonly include osteosarcoma and chondrosarcoma. Multidisciplinary treatment at a center experienced in the treatment of sarcoma is essential. Management is dictated by histologic type and grade. Surgical resection with wide margins is the cornerstone of treatment for pelvic sarcomas, although this is often challenging due to anatomic constraints of the pelvis. Multimodal treatment is critical due to the high risk of local recurrence in the pelvis.

Multidisciplinary Approach to Hemipelvectomy for Pelvic Sarcomas

» Pelvic sarcomas are a rare and diverse group of tumors in terms of size and histology.» Pelvic sarcomas present a treatment challenge to the orthopaedic oncologist.» The size and location of these tumors require a varied approach to resection and reconstruction, but the tumor's proximity to other internal structures within the pelvis (e.g., the bladder, the iliac vessels, and the bowel) makes extrication demanding.» The ideal treatment requires assembling a hemipelvectomy team that consists of an orthopaedic oncologist, a surgical oncologist, a urologist, a vascular surgeon, a gynecologic oncologist, a plastic and reconstructive surgeon, a dedicated anesthesia team, and a dedicated rehabilitation physical therapy team. Each member can use his or her expertise to address the individual aspects of the pelvic resection and achieve the optimal oncologic and functional outcome.

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.

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.

Validation of patient-specific 3D impression models for pelvic oncological orthopedic surgery

INTRODUCTION

Pelvic ring tumors pose a challenge due to the difficulty in obtaining adequate surgical margins. Tools such as surgical navigation or 3D printing for the fabrication of patient-specific surgical positioning templates help in preoperative planning and intraoperative execution. Their correct positioning is essential in complex locations such as the pelvis, so it is necessary to identify positioning errors. The aim of this study is to demonstrate the reliability of 3D template placement for pelvic ring osteotomies.

MATERIAL AND METHODS

Experimental study in cadaver with 10 hemipelvis. CT was performed to obtain the three-dimensional model, planning of osteotomies, design of positioning templates in ischiopubic (I), iliopubic (P), supracetabular (S) and iliac crest (C) branches; and a positioning marker (rigid-body) on the C and S templates for navigation. The templates and rigid-body are 3D printed and positioned according to pre-planning. Navigation allows the final position of the inserts and osteotomies to be checked.

RESULTS

The positioning of the templates with respect to the preoperative planning varied depending on the location, being greater the error in those of the iliac crest. Using navigation the mean error of distance to the cutting plane is 3.5mm, except in pubis (5-8mm), being conditioned by the position of the rigid body.

CONCLUSION

The use of patient-specific templates printed in 3D is a reliable tool for performing osteotomies in pelvic cancer surgery.

Primary malignant bone tumours of spine and pelvis in children

PURPOSE

Axial malignant bone tumours are rare in children and adolescents, and their prognosis is still relatively poor due to non-specific symptoms, such as back or groin pain, which may result in late hospital presentation. Therefore, it is very important to raise awareness regarding this pathology.

METHODS

We performed a narrative review, including scientific publications published in English. We searched Medline and Google Scholar databases for information on the incidence and prognosis of axial malignant bone tumours in children and adolescents (< 18 years). Outcomes of different surgical management strategies and reconstruction options were assessed.

RESULTS

The incidence of primary malignant bone tumours before the age of 18 years is approximately five per one million population; around 25% of these tumours are located in the axial skeleton. With a five-year survival rate of 50%, tumours in an axial location (chest cage, spine, pelvis) are associated with a poorer prognosis than tumours in more peripheral locations. En bloc excision with clear margins has been shown to improve local control and overall survival, even though obtaining adequate surgical margins is difficult due to the close location of large neurovascular structures and other major organs. Spinal reconstruction options include instrumented fusion with allograft or expandable cage. Pelvic reconstruction is needed in internal hemipelvectomy, and the options include biological, endoprosthetic reconstructions, hip transposition, arthrodesis or creation of pseudoarthrosis and lumbopelvic instrumentation.

CONCLUSION

Early diagnosis, a timely adequate multidisciplinary management, appropriate en bloc excision, and reconstruction improve survival and quality of life in these patients.

LEVEL OF EVIDENCE

V.

Patient-Specific Implants for Pelvic Tumor Resections

Introduction Limb salvage surgery for periacetabular malignancies is technically demanding and associated with a considerable likelihood of postoperative complications and surgical revision. Reconstruction using custom-made implants represents the treatment of choice. This study was conducted to analyze treatment outcomes of custom-made implants in a single orthopaedic tumor center. Patients and Methods Twenty patients with a histologically verified periacetabular malignancy and a median follow up time of 5 (1-17) years were included. Results The median number of revision surgeries per patient was 1.5 (0-7). Complications were dislocations in 3 patients, aseptic loosening in 4 patients, deep infections in 9 patients, thromboembolic events in 5 patients and sciatic nerve lesions in 4 patients. Overall survival was 77% after one year, 69% after two years and 46% after five years. Median Harris Hip Score was 81 (37-92) points at last follow up. Conclusion Although internal hemipelvectomy and reconstruction using custom-made implants is linked with a high risk of postoperative complications, good functional outcomes can be regularly achieved. This information may help treating surgeons to find adequate indications, as eligible patients need to be critically selected and integrated into the decision-making process.

A Short-Course Antibiotic Prophylaxis Is Associated with Limited Antibiotic Resistance Emergence in Post-Operative Infection of Pelvic Primary Bone Tumor Resection

Resections of primary pelvic bone tumors are frequently complicated by surgical site infections (SSIs), thereby impairing the functional prognosis of patients, especially in case of implant removal. Although prophylactic antibiotics play an essential role in preventing SSIs, there are presently no recommendations that support their appropriate use. This study aimed to assess the impact of a 24 h prophylactic protocol on the bacterial ecology, the resistance pattern, and the SSI healing rate. We hypothesized that this protocol not only limits the emergence of resistance but also results in a good cure rate with implant retention in case of SSI. A retrospective study was performed that included all patients with an SSI following a pelvic bone tumoral resection between 2005 and 2017 who received a 24 h antibiotic prophylaxis protocol. Twenty-nine patients with an SSI were included. We observed a 75.9% rate of polymicrobial infection, with a high prevalence of digestive flora microorganisms and a majority of wild-type phenotypes. We confirmed that there was no significant emergence of resistant flora. After first-line debridement, antibiotics (DA) if any implant was used, or debridement, antibiotics, and implant retention (DAIR) whenever possible, we obtained a 79.3% cure rate, with implant removal in 20% of cases. The absence of an implant was significantly associated with SSI healing. Early infection management and low resistance profiles may also have a positive effect, but this needs to be confirmed in a larger cohort. In light of this, the use of a 24 h prophylactic protocol in primary pelvic bone tumor resections is associated with a favorable infection cure rate and implant retention in case of SSI, and minimal selection of resistant microorganisms.

Limb-salvage reconstruction following resection of pelvic bone sarcomas involving the acetabulum

AIMS

Limb salvage for pelvic sarcomas involving the acetabulum is a major surgical challenge. There remains no consensus about what is the optimum type of reconstruction after resection of the tumour. The aim of this study was to evaluate the surgical outcomes in these patients according to the methods of periacetabular reconstruction.

METHODS

The study involved a consecutive series of 122 patients with a periacetabular bone sarcoma who underwent limb-salvage surgery involving a custom-made prosthesis in 65 (53%), an ice-cream cone prosthesis in 21 (17%), an extracorporeal irradiated autograft in 18 (15%), and nonskeletal reconstruction in 18 (15%).

RESULTS

The rates of major complications necessitating further surgery were 62%, 24%, 56%, and 17% for custom-made prostheses, ice-cream cone prostheses, irradiated autografts and nonskeletal reconstructions, respectively (p = 0.001). The ten-year cumulative incidence of failure of the reconstruction was 19%, 9%, 33%, and 0%, respectively. The major cause of failure was deep infection (11%), followed by local recurrence (6%). The mean functional Musculoskeletal Tumour Society (MSTS) scores were 59%, 74%, 64%, and 72%, respectively. The scores were significantly lower in patients with major complications than in those without complications (mean 52% (SD 20%) vs 74% (SD 19%); p < 0.001). For periacetabular resections involving the ilium, the mean score was the highest with custom-made prostheses (82% (SD 10%)) in patients without any major complication; however, nonskeletal reconstruction resulted in the highest mean scores (78% (SD 12%)) in patients who had major complications. For periacetabular resections not involving the ilium, significantly higher mean scores were obtained with ice-cream cone prostheses (79% (SD 17%); p = 0.031).

CONCLUSION

Functional outcome following periacetabular reconstruction is closely associated with the occurrence of complications requiring further surgery. For tumours treated with periacetabular and iliac resection, skeletal reconstruction may result in the best outcomes in the absence of complications, whereas nonskeletal reconstruction is a reasonable option if the risk of complications is high. For tumours requiring periacetabular resection without the ilium, reconstruction using an ice-cream cone prosthesis supported by antibiotic-laden cement is a reliable option. Cite this article: Bone Joint J 2021;103-B(4):795-803.

Hip transposition procedure due to osteosarcoma metastasis of the ilium in a patient with preexisting rotationplasty leads to satisfactory functional result: A case report

•

Hemipelvectomy (PI-II) after rotationplasty on the same leg resulted in a good functional result in a 16 year old male patient with osteosarcoma.

•

For hemipelvectomy, the musculus gluteus maximus is essential for soft tissue coverage, therefore supplying structures must be preserved.

•

The triradiate cartilage of the acetabulum closes around a bone age of 12 years in boys and then is no sufficient barrier for an osteosarcoma.

Introduction

The hip transposition is a limb salvage procedure for periacetabular malignancies. Here we present the case of a patient that already had a preexisting ipsilateral rotationplasty.

Presentation of case

A 16 year old male patient with an Osteosarcoma of the left distal femur was treated with wide surgical resection of the tumor and rotationplasty (Salzer/Winkelmann type A1). Despite adjuvant chemotherapy (EURAMOS protocol) he was diagnosed with metachronous metastases in the lung and in the left ilium affecting the acetabulum. As a limb salvage procedure the patient received an internal hemipelvectomy Enneking PI-II and an attachment of the femoral head with a Trevira tube to the sacrum using suture anchors. After six weeks a prosthesis was fitted and gradually full weight bearing was allowed. The patient achieved a good functional result as he was able to walk freely for three more years before he passed away.

Discussion

The hip transposition procedure does not require the implantation of a large tumor prosthesis and thus avoids the problem of an increased risk of infection. Even with preexisting ipsilateral rotationplasty a good functional outcome that allowed the patient full weight bearing could be achieved.

Conclusion

If there are already existing deformities, such as rotationplasty on the same leg, the hip transposition procedure can be considered for periacetabular malignancies, as it can achieve satisfactory results.

Soft tissue reconstruction after pelvic amputation: The efficacy and reliability of free fillet flap reconstruction

BACKGROUND

The majority of hindquarter amputation defects can be reconstructed with local anterior or posterior thigh flaps. Less than 5% of soft tissue defects require free flap reconstruction after tumour resection. Lower extremity fillet flap is described for reconstructing such defects, but the majority of publications are case reports or short single institutional series. There is a lack of data regarding the oncological outcomes of this highly selected patient group.

METHODS

Three tertiary sarcoma units treated twelve patients with hindquarter amputation or hip disarticulation for oncological indications with a free flap reconstruction of the soft tissue defect.

RESULTS

The median age of patients was 60 (range 12-76) years. Bone resection was carried out through the SI-joint in six patients and through the sacrum in five patients, with one patient undergoing hip disarticulation. Nine patients had R0 resection margin and three had R1 resection. The median surgical time and flap ischaemia time was 420 (249-650) and 89 (64-210) min, respectively. Median hospital and ICU stay was 18 (10-42) and 3 (1-8) days, respectively. Median blood loss was 2400 (950-10000) ml. There were three returns to theatre due to vascular compromise, with one total flap loss due to arterial thrombosis. Overall survival was 58% (95%CI 28-91%) both at 1-year and at 3-years.

DISCUSSION

Carefully selected patients requiring hindquarter amputation with extensive soft tissue defect necessitating free flap reconstruction can be reconstructed with a lower extremity free fillet flap with low rate of local wound complications. Survival of these patients is similar to that in patients requiring less extensive resection.

Gigantic secondary pelvic chondrosarcomas treated with pelvic resection type I and III: A case report

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Proper selection of patients, preoperative planning and wide surgical margins with reconstruction provides good local control and clinical outcomes following pelvic resection.

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Patient with huge tumor need large amount of blood transfusion and postoperative intensive care due to longer surgery time.

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The surgical site infection is common complication after pelvic resection and can be managed with debridement and antibiotic therapy.

Introduction

Patients with osteochondromatosis have a higher risk of malignant transformation into secondary chondrosarcoma. Chondrosarcoma at the pelvic region tends to present late and therefore pose a significant challenge for orthopedic surgeons because of the large tumor size, local extension, and complex anatomy with proximity to major neurovascular structure, intestinal and urinary tract.

Presentation of case

A 44-year-old male presented the chief complaint of 15 years growing lumps on his left buttock and right groin, presenting with pain. Plain radiography revealed popcorn calcification at the left iliac wing and right superior pubic rami. Multiple exostoses were also visible. MRI showed a larger tumor diameter at the left iliac wing by 33 cm and right pubic rami by 13 cm. The histopathological result from the biopsy suggested low-grade chondrosarcoma.

Result

The patient underwent pelvic resection type I and III in two-stage surgery. About one month after the first surgery, there was a postoperative infection. Debridement and antibiotic therapy resulted in a desirable functional outcome with an MSTS score 27 and no local recurrence sign during a one-year follow-up.

Discussion

Low-grade chondrosarcomas are not sensitive to radiation and chemotherapy; wide surgical resection is the mainstay of treatment. Chondrosarcoma at the iliac wing can be treated by pelvic resection type I, and further reconstruction needed to prevent pelvic tilting. Chondrosarcoma at pubic rami can be treated by pelvic resection type III.

Conclusion

Proper patient selections, preoperative planning, and wide surgical margins with reconstruction provide desirable local control and clinical outcomes following pelvic resection.

Surgical and oncological outcomes after hindquarter amputation for pelvic sarcoma

Aims

Survival rates and local control after resection of a sarcoma of the pelvis compare poorly to those of the limbs and have a high incidence of complications. The outcome for patients who need a hindquarter amputation (HQA) to treat a pelvic sarcoma is poor. Our aim was to evaluate the patient, tumour, and reconstructive factors that affect the survival of the patients who undergo HQA for primary or recurrent pelvic sarcoma.

Methods

We carried out a retrospective review of all sarcoma patients who had undergone a HQA in a supraregional sarcoma unit between 1996 and 2018. Outcomes included oncological, surgical, and survival characteristics.

Results

A total of 136 patients, with a mean age of 51 (12 to 83) underwent HQA, 91 for a bone sarcoma and 45 for a soft tissue sarcoma. The overall survival (OS) after primary HQA for a bone sarcoma was 90.7 months (95% confidence interval (CI) 64.1 to 117.2). In patients undergoing a secondary salvage HQA it was 90.3 months (95% CI 58.1 to 122.5) (p = 0.727). For those treated for a soft tissue sarcoma (STS), the mean OS was 59.3 months (95% CI 31.1 to 88.6) for patients with a primary HQA, and 12.5 months (95% CI 9.4 to 15.5) for those undergoing a secondary salvage HQA (p = 0.038). On multivariate analysis, high histological grade (hazard ratio (HR) 2.033, 95% CI 1.127 to 3.676; p = 0.018) and a diagnosis of STS (HR 1.653, 95% CI 1.027 to 2.660; p = 0.039) were associated with a poor prognosis. The 30-day mortality for patients with curative intent was 0.8% (1/128). For those in whom surgery was carried out with palliative intent it was 33.3% (2/6) (p = 0.001). In total, 53.7% (n = 73) of patients had at least one complication with 23.5% (n = 32) requiring at least one further operation. Direct closure was inferior to flap reconstruction in terms of complete primary wound healing (60.0% (3/5) vs 82.0% (82/100); p = 0.023).

Conclusion

In carefully selected patients HQA is associated with satisfactory overall survival, with a low risk of perioperative mortality, but considerable morbidity. However, caution must be exercised when considering the procedure for palliation due to the high incidence of early postoperative mortality. Cite this article: Bone Joint J 2020;102-B(6):788–794.

[Treatment concepts for complications after resection and defect reconstruction of pelvic tumours]

BACKGROUND

Partial pelvic resection, internal hemipelvectomy or sacrectomy as a result of bone sarcoma is still challenging. No matter what kind of reconstruction is used, there is still a much higher rate of complications in pelvic surgery compared to sarcoma surgery of the long bones.

OBJECTIVES

We describe the most common complications in pelvic sarcoma surgery and specific complications related to the reconstruction method. Handling strategies for these complications are specified.

METHODS

We performed a literature search and report our own experiences in the troubleshooting of pelvic surgery-related complications to gain an up-to-date overview of the state-of-the-art in management strategies.

RESULTS

Prospective randomized trials or meta-analyses on this topic are lacking. The literature search depicted that, besides local recurrence, deep infection after reconstruction is the most serious complication. An early revision with radical debridement has to be performed in order to save the reconstruction. In the case of a deep infection, the removal of all implants with a total loss of the reconstruction is often unavoidable. Therefore, an individualized risk-benefit analysis prior to surgery with respect to the type of reconstruction, or no reconstruction at all (hip transposition), together with the patient is advisable.

CONCLUSIONS

Complications-especially infections-after hemipelvectomy or sacrectomy are common. In the case of infection, in some cases, an early revision is the only chance to prevent a reconstruction from explantation.

Thirty-Day Outcomes after Surgery for Primary Sarcomas of the Extremities: An Analysis of the NSQIP Database

Background

Primary bone and soft tissue sarcomas are rare tumors requiring wide surgical resection and reconstruction to achieve local control. Postoperative complications can lead to delays in adjuvant therapy, potentially affecting long-term oncologic outcomes. Understanding postoperative complication risks is essential; however, past studies are limited by small sample sizes.

Purpose

This study uses a large national registry to characterize the incidence of complications and mortality in the first thirty days following surgical management of primary bone and soft tissue sarcomas of the extremities.

Methods

A retrospective review of patients in the National Surgical Quality Improvement Program database was performed. Cases were identified using diagnosis codes for malignant neoplasm of soft tissue or bone and procedure codes for amputation and radical resection. The cohort was subdivided by bone versus soft tissue sarcoma, upper versus lower extremity, and amputation versus limb salvage.

Results

One thousand, one hundred eleven patients were identified. The most frequent complications were surgical site infections, sepsis, and venous thromboembolism. The overall incidence of complications was 14.0%. Unplanned readmission and reoperation occurred after 7.0% and 8.0% of cases, respectively. Thirty-day mortality was 0.3%, with one intraoperative death. Patient factors and complication rates varied by tumor location and surgical modality. Lower extremity cases were associated with higher rates of wound complications and infectious etiologies such as surgical site infections, urinary tract infections, and systemic sepsis. In contrast, patients undergoing amputation were more likely to experience major medical complications including acute renal failure, cardiac arrest, and myocardial infarction.

Conclusion

Approximately 1 in 7 patients will experience a complication in the first thirty days following surgery for primary bone and soft tissue sarcomas of the extremities. The unique risk profiles of lower extremity and amputation cases should be considered during perioperative planning and surveillance.

Antimicrobial Prophylaxis for the Prevention of Surgical Site Infections in Orthopaedic Oncology - A Narrative Review of Current Concepts

The incidence of surgical site infections (SSIs) after elective tumour orthopaedic surgery in adults is higher than non-oncologic orthopaedic surgery. Their causative microorganisms and antibiotic susceptibilities are also different from the non-oncologic cases; with no apparent predictable microbiological patterns. Clinicians continue to struggle to tailor the optimal prophylactic regimen for the very heterogeneous group of tumour patients. Many clinicians thus prolong the first-and second-generation cephalosporin agents, while a minority chooses to broaden the antimicrobial spectrum by combination prophylaxis. The variability in current practices and surgical techniques is enormous, even within the same setting. The scientific literature lacks adequate retrospective case-studies and there is currently only one prospective randomized trial. In this narrative review, we discuss various perioperative antibiotic concepts in oncologic orthopaedic surgery, including a summary of the state-to-the-art, opinions and difficulties related to the different prophylactic strategies.

[Hemipelvectomy for pelvic sarcomas]

BACKGROUND

Hemipelvectomy is an important technique for the treatment of pelvic sarcomas.

OBJECTIVES

Presentation of the technical overview, as well as surgical and oncological outcomes of sarcoma patients treated with pelvic tumor resections and treatment recommendations.

METHODS

Retrospective analysis of 160 patients treated by pelvic tumor resection for chondrosarcoma between 1977 and 2014.

RESULTS

Chondrosarcoma was the most common diagnosis leading to pelvic tumor resection in this collective (38%). The mean patient age at operation was 49 years. 44 patients were treated for G1, 83 patients for G2 and 33 patients for G3 or dedifferentiated chondrosarcoma. The mean tumor diameter was ≥10 cm in 76.1% of cases. Limb salvaging operations were possible in 82.5% of patients. The most common reconstruction technique was hip transposition (38.7%). Clear resection margins were achieved in 86.9% (R0). Local recurrence was observed in 22.5%. Distant pulmonal metastasis was diagnosed in 25% of patients. Grading-specific survival was 81.8% for G1, 59% for G2 and 24.2% for G3 or dedifferentiated chondrosarcoma with a mean survival of 84.4, 89 and 69.4 months respectively.

CONCLUSIONS

Pelvic tumor resection with clear margins is the most important known positive predictive local factor affecting overall outcomes, in addition to uncontrollable factors such as grading and tumor size. Defect reconstruction depends on multiple factors such as patient age and adjuvant therapy. The stage of the disease has the greatest impact on overall survival rates and should be considered when contemplating pelvic tumor resections in sarcoma patients.

Surgical treatment for pelvic Ewing sarcoma: What is a safe and functional acetabular reconstruction when combined with modern multidisciplinary treatments?

PURPOSE

The purpose of this study was to clarify which local treatment is oncologically and functionally effective in pelvic Ewing sarcoma (ES).

METHODS

A consecutive series of patients who underwent pelvic resections and acetabular reconstructions after chemotherapy between 1986 and 2016 at a supra-regional center were evaluated.

RESULTS

The cohort consisted of 35 patients. The 5-year overall survival (OS) and local recurrence-free survival (LRFS) was 61% and 72%, respectively. Preoperative radiotherapy (RT) and surgery provided an excellent/good histological response in 92% and achieved significantly better OS (5 years, 64%) and LRFS (5 years, 100%) than surgery alone or surgery with postoperative RT. The Musculoskeletal Tumor Society functional scores were significantly better in patients with hip transposition than those with structural reconstructions (74% vs 57%; P = .031) using custom-made prostheses, irradiated autografts, and ice-cream cone prostheses. These scores were significantly lower if patients had deep infection (P = .035), which was the most common complication (28%) in structural reconstructions but did not occur in hip transposition even when performed after preoperative RT.

CONCLUSION

Acetabular reconstruction with hip transposition resulted in no deep infection and superior function in patients with pelvic ES even when combined with preoperative RT, which improved tumor necrosis and rate of local control and survival.

Prognostic nomograms to predict overall survival and cancer-specific survival in patients with pelvic chondrosarcoma

Background

The pelvis is the most common site of chondrosarcoma (CS), and the prognosis for patients with pelvic CS is worse than that for patients with CS in the extremities. However, clinicians have had few tools for estimating the likelihood of survival in patients with pelvic CS. Our aim was to develop nomograms to predict survival of patients with pelvic CS.

Methods

Data from the Surveillance, Epidemiology, and End Results (SEER) database of patients with pelvic CS between 2004 and 2016 were retrieved for retrospective analysis. Univariate and multivariate Cox analyses were used to identify independent prognostic factors. On the basis of the results of the multivariate analyses, nomograms were constructed to predict the likelihood of 3‐ and 5‐year overall survival (OS) and cancer‐specific survival (CSS) of patients with pelvic CS. The concordance index (C‐index) and calibration curves were used to test the models.

Results

In univariate and multivariate analyses of OS, sex, pathologic grade, tumor size, tumor stage, and surgery were identified as the independent risk factors. In univariate and multivariate analyses of CSS, pathologic grade, tumor size, tumor stage, and surgery were identified as the independent risk factors. These characteristics except surgery were integrated in the nomograms for predicting 3‐ and 5‐year OS and CSS, and the C‐indexes were 0.758 and 0.786, respectively.

Conclusion

The nomograms precisely and individually predict OS and CSS of patients with pelvic CS and could aid in personalized prognostic evaluation and individualized clinical decision‐making.

Is a Modular Pedicle-hemipelvic Endoprosthesis Durable at Short Term in Patients Undergoing Enneking Type I + II Tumor Resections With or Without Sacroiliac Involvement?

BACKGROUND

Functional reconstruction after Enneking Type I + II resections of the pelvis (those involving both the ilium and the acetabulum) is challenging, especially if resection of part of the sacrum is included. To assess the clinical outcomes of a newly designed modular pedicle-hemipelvic endoprosthesis, we performed a preliminary retrospective study on its clinical use in a small group of patients.

QUESTIONS/PURPOSES

The purposes of this study were (1) to evaluate in a small case series whether the new endoprosthesis restored lower limb function and lumbopelvic stability in the short term; (2) to identify the complications associated with use of the new prosthesis; and (3) to assess the 5-year cumulative survival, the cumulative incidence of a major postoperative event, and the cumulative incidence of implant failure in this group of patients.

METHODS

Between August 2012 and August 2014, our center performed 274 internal hemipelvectomies for oncologic indications. Among these, 20 were treated with the new endoprosthesis, which was designed for fixation both to the residual sacrum as well as the lumbar spine. An earlier version of the device had been removed from the market because of an unacceptable risk of serious complications. All of the 20 tumors were sarcomas necessitating en bloc resection. The implant is modular and can meet the different-sized defects in each patient. The general indication for use of the new implant was a total acetabular defect with extensive iliac involvement or total loss of the sacroiliac joint and/or hemisacrum. All 20 patients were followed up for a minimum of 24 months or until death in those patients who survived < 2 years (median, 36 months; range, 6-60 months). The clinical data were retrieved from the database and the study endpoints (function according to the Musculoskeletal Tumor Society [MSTS] score, complications, and survivorship of patients and implants) were ascertained by chart review. Lumbopelvic stability was defined as an excellent or good rating according to the International Society of Limb Salvage radiologic implant evaluation system. The cumulative survival of patients was estimated using the Kaplan-Meier approach. The cumulative incidence of major postoperative events including local recurrence, metastasis, and reoperation was estimated using a competing events analysis; the cumulative incidence of implant failure, including mechanical failure or deep infection, in patients who underwent reoperation was also estimated using a competing events analysis.

RESULTS

In the 16 patients who survived > 12 months, the median MSTS score was 19 of 30 (range, 5-26). Radiographic assessments demonstrated lumbopelvic stability in all of the 16 patients. Twelve of 20 patients developed postoperative complications, primarily including deep infection (one), hip dislocation (two), and local recurrence (three). Major revision surgery was performed in five of 20 patients. The estimated 5-year Kaplan-Meier patient survival rate was 69% (95% confidence interval [CI], 59%-79%), whereas the cumulative incidence of major postoperative events and implant failure using the competing risk estimator was 42% (95% CI, 23%-60%) and 15% (95% CI, 4%-34%) at 5 years, respectively.

CONCLUSIONS

Preliminary results with hemipelvic reconstruction using this new endoprosthesis achieved fair functional results and the complications that were observed appeared comparable to other reconstruction options at short-term followup. Longer-term surveillance is called for to see whether this implant will be durable compared with other available reconstructive alternatives such as a custom-made megaendoprosthesis or an autograft/allograft-prosthetic composite.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Additive manufacturing technique-designed metallic porous implants for clinical application in orthopedics

Traditional metallic scaffold prostheses, as vastly applied implants in clinical orthopedic operations, have achieved great success in rebuilding limb function. However, mismatch of bone defects and additional coating requirements limit the long-term survival of traditional prostheses. Recently, additive manufacturing (AM) has opened up unprecedented possibilities for producing complicated structures in prosthesis shapes and microporous surface designs of customized prostheses, which can solve the drawback of traditional prostheses mentioned above. This review presents the most commonly used metallic additive manufacturing techniques, the microporous structure design of metallic scaffolds, and novel applications of customized prostheses in the orthopedic field. Challenges and future perspectives on AM fabricated scaffolds are also summarized.