Can Navigation-assisted Surgery Help Achieve Negative Margins in Resection of Pelvic and Sacral Tumors?

Can 3D-printed patient-specific instruments improve local control and overall survival in pelvic sarcoma? A clinical validation study

BACKGROUND AND OBJECTIVES

3D-printed patient-specific instruments (PSIs), also known as 3D guides, have been shown to improve accuracy in resection of pelvic tumors in cadaver studies and achieve better surgical margins in vivo. This study evaluates the clinical impact of 3D-printed guides on medium-term local and distant disease control, as well as disease-free and overall survival in patients.

MATERIAL AND METHODS

A cohort study included 25 patients with primary pelvic or sacral sarcomas: 10 in the 3D group and 15 in the control group, with a median follow-up of 47 months. Demographic and clinical data, including tumor histology, stage, resection technique, associated reconstruction, adjuvant therapies, and complications, were evaluated. Surgical margins (free, marginal, and contaminated) and relapse-free and overall survival curves were analyzed.

RESULTS

The 3D group achieved a higher rate of free margins (80% vs 66.7%, p = 0.345). Local recurrence (50% vs 60%, P=.244) and distant disease relapse (20% vs 47%, p = 0.132) rates were lower in the 3D group. At the end of the follow-up, the 3D group had a higher overall survival rate (60% vs 40%, p = 0.327). The complication rate was similar in both groups, with a deep infection rate of 40%.

CONCLUSIONS

The use of 3D guides in resecting primary pelvic tumors not only achieves a higher rate of free margins compared to conventional techniques but also shows a trend towards higher local, distant, and overall disease-free survival. Further studies with larger sample sizes and higher levels of evidence are necessary to validate these clinical trends.

Computerized surgical navigation resection of pelvic region simulated bone tumors using skin fiducial marker registration: an in vitro cadaveric study

INTRODUCTION

Computerized surgical navigation system guidance can improve bone tumor surgical resection accuracy. This study compared the 10-mm planned resection margin agreement between simulated pelvic-region bone tumors (SPBT) resected using either skin fiducial markers or Kirschner (K)-wires inserted directly into osseous landmarks with navigational system registration under direct observation. We hypothesized that skin fiducial markers would display similar resection margin accuracy.

METHODS

Six cadaveric pelvises had one SPBT implanted into each supra-acetabular region. At the left hemi-pelvis, the skin fiducial marker group had guidance from markers placed over the pubic tubercle, the anterior superior iliac spine, the central and more posterior iliac crest, and the greater trochanter (5 markers). At the right hemi-pelvis, the K-wire group had guidance from 1.4-mm-diameter wires inserted into the pubic tubercle, and 3 inserted along the iliac crest (4 K-wires). The senior author, a fellowship-trained surgeon performed "en bloc" SPBT resections. The primary investigator, blinded to group assignment, measured actual resection margins.

RESULTS

Twenty of 22 resection margins (91%) in the skin fiducial marker group were within the Bland-Altman plot 95% confidence interval for actual-planned margin mean difference (mean = -0.23 mm; 95% confidence intervals = 2.8 mm, - 3.3 mm). Twenty-one of 22 resection margins (95%) in the K-wire group were within the 95% confidence interval of actual-planned margin mean difference (mean = 0.26 mm; 95% confidence intervals = 1.7 mm, - 1.1 mm).

CONCLUSION

Pelvic bone tumor resection with navigational guidance from skin fiducial markers placed over osseous landmarks provided similar accuracy to K-wires inserted into osseous landmarks. Further in vitro studies with different SPBT dimensions/locations and clinical studies will better delineate use efficacy.

Surgical and Oncologic Outcome following Sacrectomy for Primary Malignant Bone Tumors and Locally Recurrent Rectal Cancer

INTRODUCTION

Bone sarcoma or direct pelvic carcinoma invasion of the sacrum represent indications for partial or total sacrectomy. The aim was to describe the oncosurgical management and complication profile and to analyze our own outcome results following sacrectomy.

METHODS

In a retrospective analysis, 27 patients (n = 8/10/9 sarcoma/chordoma/locally recurrent rectal cancer (LRRC)) were included. There was total sacrectomy in 9 (incl. combined L5 en bloc spondylectomy in 2), partial in 10 and hemisacrectomy in 8 patients. In 12 patients, resection was navigation-assisted. For reconstruction, an omentoplasty, VRAM-flap or spinopelvic fixation was performed in 20, 10 and 13 patients, respectively.

RESULTS

With a median follow-up (FU) of 15 months, the FU rate was 93%. R0-resection was seen in 81.5% (no significant difference using navigation), and 81.5% of patients suffered from one or more minor-to-moderate complications (especially wound-healing disorders/infection). The median overall survival was 70 months. Local recurrence occurred in 20%, while 44% developed metastases and five patients died of disease.

CONCLUSIONS

Resection of sacral tumors is challenging and associated with a high complication profile. Interdisciplinary cooperation with visceral/vascular and plastic surgery is essential. In chordoma patients, systemic tumor control is favorable compared to LRRC and sarcomas. Navigation offers gain in intraoperative orientation, even if there currently seems to be no oncological benefit. Complete surgical resection offers long-term survival to patients undergoing sacrectomy for a variety of complex diseases.

Surgical Margins in Musculoskeletal Sarcoma

» Negative margin resection of musculoskeletal sarcomas is associated with reduced risk of local recurrence.» There is limited evidence to support an absolute margin width of soft tissue or bone that correlates with reduced risk of local recurrence.» Factors intrinsic to the tumor, including histologic subtype, grade, growth pattern and neurovascular involvement impact margin status and local recurrence, and should be considered when evaluating a patient's individual risk after positive margins.» Appropriate use of adjuvant therapy, critical analysis of preoperative advanced cross-sectional imaging, and the involvement of a multidisciplinary team are essential to obtain negative margins when resecting sarcomas.

Advances in Virtual Cutting Guide and Stereotactic Navigation for Complex Tumor Resections of the Sacrum and Pelvis: Case Series with Short-Term Follow-Up

Primary malignancies of the sacrum and pelvis are aggressive in nature, and achieving negative margins is essential for preventing recurrence and improving survival after en bloc resections. However, these are particularly challenging interventions due to the complex anatomy and proximity to vital structures. Using virtual cutting guides to perform navigated osteotomies may be a reliable method for safely obtaining negative margins in complex tumor resections of the sacrum and pelvis. This study details the technique and presents short-term outcomes. Patients who underwent an en bloc tumor resection of the sacrum and/or pelvis using virtual cutting guides with a minimum follow-up of two years were retrospectively analyzed and included in this study. Preoperative computer-assisted design (CAD) was used to design osteotomies in each case. Segmentation, delineating the tumor from normal tissue, was performed by the senior author using preoperative CT scans and MRI. Working with a team of biomedical engineers, virtual surgical planning was performed to create osteotomy lines on the preoperative CT and overlaid onto the intraoperative CT. The pre-planned osteotomy lines were visualized as "virtual cutting guides" providing real-time stereotactic navigation. A precision ultrasound-powered cutting tool was then integrated into the navigation system and used to perform the osteotomies in each case. Six patients (mean age 52.2 ± 17.7 years, 2 males, 4 females) were included in this study. Negative margins were achieved in all patients with no intraoperative complications. Mean follow-up was 38.0 ± 6.5 months (range, 24.8-42.2). Mean operative time was 1229 min (range, 522-2063). Mean length of stay (LOS) was 18.7 ± 14.5 days. There were no cases of 30-day readmissions, 30-day reoperations, or 2-year mortality. One patient was complicated by flap necrosis, which was successfully treated with irrigation and debridement and primary closure. One patient had local tumor recurrence at final follow-up and two patients are currently undergoing treatment for metastatic disease. Using virtual cutting guides to perform navigated osteotomies is a safe technique that can facilitate complex tumor resections of the sacrum and pelvis.

Ewing's sarcoma of proximal femur: case report of extreme osteotomy with 3D-printed prosthesis for the reconstruction

Background: Resection and reconstruction of malignant bone tumors at the proximal femur in adolescent patients has remained a clinical challenge. Considering the growth and development requirements of adolescents, there is no unified standard for the reconstruction of bone defects at the proximal femur. Here, we report a case of 3D-printed titanium alloy customized prosthesis for the construction of proximal femoral bone defects in an adolescent patient with Ewing's sarcoma of the proximal femur. Case presentation: A 7-year-old female patient presented to a local hospital with left hip pain, and was diagnosed with Ewing's sarcoma on the proximal left femur. The patient received two courses of neoadjuvant chemotherapy before surgery according to the standard protocol. Considering growth and development problems associated with adolescents, we adopted a customized 3D-printed prosthesis of proximal femur for preservation of the femoral head and part of the femoral neck in the affected limb. Clinical outcomes, recorded after 12 months of follow-up, revealed excellent functional recovery and satisfactory functional scores of the affected limb, with no immediate complications. Conclusion: 3D-printed prosthesis is a feasible method for preserving femoral head and reconstruction of bone defects in adolescents' proximal femur.

Accuracy of bony resection under computer-assisted navigation for bone sarcomas around the knee

BACKGROUND

Computer-assisted navigation has made bone sarcoma resections more precise. However, further clinical studies involving accuracy analyses under navigation are still warranted.

METHODS

A retrospective study for analysis of computer-assisted navigation accuracy was carried out. Between September 2008 and November 2017, 39 cases of bone sarcomas around the knee joint were resected under computer-assisted navigation. The control group comprised 117 cases of bone sarcomas around the knee treated by limb salvage surgery wherein bony cutting was achieved freehand. The length difference (LD) was defined as the specimen length minus the planned resection length. The LDs were detected in both groups and compared. The margin accuracy (MA) was defined as the achieved margin minus the desired margin at the bone cutting site and was detected in the navigation group.

RESULTS

The LDs between the postoperative specimen length and the preoperative planned length were compared. In the navigation group, the LD was 0.5 ± 2.5 mm (range, - 5 to 5 mm), while in the freehand group, the LD was 3.4 ± 9.6 mm (range, - 20 to 29 mm), with a significant difference (P < 0.01). In the absolute value analysis, the LD absolute value was 2.0 ± 1.6 mm in the navigation group and 8.3 ± 6.0 mm in the freehand group, with a significant difference (P < 0.01). In the navigation group, the MA was 0.3 ± 1.5 mm (range, - 3 to 3 mm) and the MA absolute value was 1.1 ± 1.0 mm.

CONCLUSIONS

Better accuracy can be achieved when computer-assisted navigation is conducted for bone sarcoma resection around the knee.

LEVEL OF EVIDENCE

IV.

Internal Hemipelvectomy for primary bone sarcomas using intraoperative patient specific instruments- the next step in limb salvage concept

BACKGROUND

During pelvic Sarcoma resections, Surgeons often struggle to obtain negative margins while minimizing collateral damage and maintaining limb function. These complications are usually due to the complex anatomy of the pelvis. Here we present an accurate 3D surgical approach, including pre-operative printing of models and intraoperative patient-specific instruments (PSIs) for optimizing pelvic sarcoma resections.

METHODS

This single-center retrospective study (N = 11) presents surgical, functional, and oncological outcomes of patients (average age 14.6 +/- 7.6 years, 4 males) who underwent pelvic sarcoma resections using a 3D surgical approach between 2016 and 2021. All patients were followed up for at least 24 months (mean = 38.9 +/- 30.1 months).

RESULTS

Our results show promising surgical, oncological, and functional outcomes. Using a 3D approach, 90.9% had negative margins, and 63.6% did not require reconstruction surgery. The average estimated blood loss was 895.45 ± 540.12 cc, and the average surgery time was 3:38 ± 0.05 hours. Our results revealed no long-term complications. Three patients suffered from short-term complications of superficial wound infections. At 24 month follow up 72.7% of patients displayed no evidence of disease. The average Musculoskeletal Tumor Society (MSTS) score at 12 months was 22.81.

CONCLUSION

3D technology enables improved accuracy in tumor resections, allowing for less invasive procedures and tailored reconstruction surgeries, potentially leading to better outcomes in function and morbidity. We believe that this approach will enhance treatments and ease prognosis for patients diagnosed with pelvic sarcoma and will become the standard of care in the future.

Periosteal preservation: a new technique in resection of bone high-grade malignant tumors in children-about eleven cases

Objective

The purpose of this study was to describe a surgical technique of bone resection with periosteal preservation and reconstruction in patients with high-grade bone malignant tumors and to determine its effect on local recurrences, and time and quality of bone union in bone autografting reconstruction.

Patients and methods

We retrospectively reviewed 11 cases of high-grade malignant bone tumors in children aged 4 to 16 years, who were treated with chemotherapy and tumor resection while preserving partially the adjacent periosteum. Tumors were located in the lower limb in eight cases; three tumors were in the humerus. The mean length of the bone defect after resection was 15.8 cm (range, 6–34.5 cm). Reconstruction was provided by non-vascularized autograft in eight cases (lower limb) and polymethyl methacrylate spacer in three cases (upper limb). Patients were followed up for a mean of 71 months.

Results

At the last follow-up, no patients had local recurrence. Three patients were dead because of metastasis. Bone union was good in time and quality in all children who had bone autografting. In cases of PMMA reconstruction, there was periosteal bone formation around the spacer. According to the MSTS functional score, patients with lower limb localizations had a mean score of 27.75 points and patients with upper limb localizations had a score of 24/30.

Conclusion

Preservation of the periosteum in bone resection for malignant tumors could be a good adjuvant alternative for bone reconstruction, without increasing the risk of local recurrence. However, patients must be carefully selected.

Review and Future/Potential Application of Mixed Reality Technology in Orthopaedic Oncology

In orthopaedic oncology, surgical planning and intraoperative execution errors may result in positive tumor resection margins that increase the risk of local recurrence and adversely affect patients’ survival. Computer navigation and 3D-printed resection guides have been reported to address surgical inaccuracy by replicating the surgical plans in complex cases. However, limitations include surgeons’ attention shift from the operative field to view the navigation monitor and expensive navigation facilities in computer navigation surgery. Practical concerns are lacking real-time visual feedback of preoperative images and the lead-time in manufacturing 3D-printed objects. Mixed Reality (MR) is a technology of merging real and virtual worlds to produce new environments with enhanced visualizations, where physical and digital objects coexist and allow users to interact with both in real-time. The unique MR features of enhanced medical images visualization and interaction with holograms allow surgeons real-time and on-demand medical information and remote assistance in their immediate working environment. Early application of MR technology has been reported in surgical procedures. Its role is unclear in orthopaedic oncology. This review aims to provide orthopaedic tumor surgeons with up-to-date knowledge of the emerging MR technology. The paper presents its essential features and clinical workflow, reviews the current literature and potential clinical applications, and discusses the limitations and future development in orthopaedic oncology. The emerging MR technology adds a new dimension to digital assistive tools with a more accessible and less costly alternative in orthopaedic oncology. The MR head-mounted display and hand-free control may achieve clinical point-of-care inside or outside the operating room and improve service efficiency and patient safety. However, lacking an accurate hologram-to-patient matching, an MR platform dedicated to orthopaedic oncology, and clinical results may hinder its wide adoption. Industry-academic partnerships are essential to advance the technology with its clinical role determined through future clinical studies.

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[Update on 3D printing in the surgery of musculoskeletal tumors]

The importance of 3D printing applications in the surgery of musculoskeletal tumors has increased in recent years. Even prior to the era of 3D printing, computer-assisted techniques, such as navigation, have proved their utility. Due to the variable appearance of bone tumors, there is a need for individual solutions. The 3D printing can be used for the development of anatomical demonstration models, the construction of patient-specific instruments and custom-made implants. For these three applications, different regulatory hurdles exist. Especially for the resection of pelvic tumors, 3D printing technologies seem to provide advantages due to the complicated anatomy and the proximity to relevant neurovascular structures. With the introduction of titanium printing, construction of individualized implants that fit exactly into the defect became feasible.

Evaluation of a novel classification system to predict local recurrence in sarcoma patients undergoing hemipelvectomy with iliosacral resection

AIMS

Iliosacral sarcoma resections have been shown to have high rates of local recurrence (LR) and poor overall survival. There is also no universal classification for the resection of pelvic sarcomas invading the sacrum. This study proposes a novel classification system and analyzes the survival and risk of recurrence, when using this system.

METHODS

This is a retrospective analysis of 151 patients (with median follow-up in survivors of 44 months (interquartile range 12 to 77)) who underwent hemipelvectomy with iliosacral resection at a single centre between 2007 and 2019. The proposed classification differentiates the extent of iliosacral resection and defines types S1 to S6 (S1 resection medial and parallel to the sacroiliac joint, S2 resection through the ipsilateral sacral lateral mass to the neuroforamina, S3 resection through the ipsilateral neuroforamina, S4 resection through ipsilateral the spinal canal, and S5 and S6 contralateral sacral resections). Descriptive statistics and the chi-squared test were used for categorical variables, and the Kaplan-Meier survival analysis were performed.

RESULTS

Resections were S1 in 25/151 patients (17%), S2 in 70/151 (46%), S3 in 33/151 (22%), S4 in 77/151 (11%), S5 in 4/151 (3%), and S6 in 2/151 (1%). An internal hemipelvectomy was performed in 113/151 patients (75%), and 38/151 patients (25%) had an external hemipelvectomy. The predominant types of sarcoma were high-grade osteosarcoma in 48/151 patients (32%), chondrosarcoma in 41/151 (27%), Ewing sarcoma in 33/151 (22%), pleomorphic sarcoma in 17/151 (11%), and others in 2/151 (8%). LR was found in 24/151 patients (15%) with S3, S5, with S6 resections showing the highest rate of LR (p = 0.038). Overall, 19/151 patients (16%) had evidence of metastastic disease at the time of surgery and these patients showed poorer survival when compared to patients with no metastasis.

CONCLUSION

The proposed classification can help to report and compare different surgical and reconstructive approaches in these difficult cases who are still have a considerable risk of LR. Cite this article: Bone Joint J 2022;104-B(2):290-296.

Computer navigation-aided joint-preserving resection and custom-made endoprosthesis reconstruction for bone sarcomas: long-term outcomes

BACKGROUND

Computed tomography (CT) and magnetic resonance imaging (MRI) data can be fused to identify the tumor boundaries. This enables surgeons to set close but tumor-free surgical margins and excise the tumor more precisely. This study aimed to report our experience in performing computer navigation-aided joint-preserving resection and custom-made endoprosthesis reconstruction to treat bone sarcoma in the diaphysis and metaphysis of the femur and tibia.

METHODS

Between September 2008 and December 2015, 24 patients with bone sarcomas underwent surgical resection and joint-sparing reconstruction under image-guided computer navigation. The cohort comprised 16 males and eight females with a median age of 19.5 years (range: 12-48 years). The tumor location was the femoral diaphysis in three patients, distal femur in 19, and proximal tibia in two. The tumors were osteosarcoma (n = 15), chondrosarcoma (n = 3), Ewing sarcoma (n = 3), and other sarcomas (n = 3). We created a pre-operative plan for each patient using navigation system software and performed navigation-aided resection before reconstructing the defect with a custom-made prosthesis with extracortical plate fixation.

RESULTS

Pathological examination verified that all resected specimens had appropriate surgical margins. The median distance from the tumor resection margin to the joint was 30 mm (range: 13-80 mm). The median follow-up duration was 62.5 months (range: 24-134 months). Of the 24 patients, 21 remain disease free, one is alive with disease, and two died of the disease. One patient developed local recurrence. Complications requiring additional surgical procedures occurred in six patients, including one with wound hematoma, one with delayed wound healing, one with superficial infection, one with deep infection, and two with mechanical failure of the prosthesis. The mean Musculoskeletal Tumor Society score at the final follow-up was 91% (range: 80%-100%). The 5- and 10-year implant survival rates were 91.3% and 79.9%, respectively.

CONCLUSIONS

Computer navigation-aided joint-preserving resection and custom-made endoprosthesis reconstruction with extracortical plate fixation is a reliable surgical treatment option for bone sarcoma in the diaphysis and metaphysis of the femur and tibia.

Computer-Assisted Surgical Navigation for Primary and Metastatic Bone Malignancy of the Pelvis: Current Evidence and Future Directions

Computer-assisted navigation and robotic surgery have gained popularity in the treatment of pelvic bone malignancies, given the complexity of the bony pelvis, the proximity of numerous vital structures, and the historical challenges of pelvic bone tumor surgery. Initial interest was on enhancing the accuracy in sarcoma resection by improving the quality of surgical margins and decreasing the incidence of local recurrences. Several studies have shown an association between intraoperative navigation and increased incidence of negative margin bone resection, but long-term outcomes of navigation in pelvic bone tumor resection have yet to be established. Historically, mechanical stabilization of pelvic bone metastases has been limited to Harrington-type total hip arthroplasty for disabling periacetabular disease, but more recently, computer-assisted surgery has been employed for minimally invasive percutaneous fixation and stabilization; although still in its incipient stages, this procedure is potentially appealing for treating patients with bone metastases to the pelvis. The authors review the literature on navigation for the treatment of primary and metastatic tumors of the pelvic bone and discuss the best practices and limitations of these techniques.

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.

Surgical navigation for challenging recurrent or pretreated intra-abdominal and pelvic soft tissue sarcomas

BACKGROUND

This study assessed whether electromagnetic navigation can be of added value during resection of recurrent or post-therapy intra-abdominal/pelvic soft tissue sarcomas (STS) in challenging locations.

MATERIALS AND METHODS

Patients were included in a prospective navigation study. A pre-operatively 3D roadmap was made and tracked using electromagnetic reference markers. During the operation, an electromagnetic pointer was used for the localization of the tumor/critical anatomical structures. The primary endpoint was feasibility, secondary outcomes were safety and usability.

RESULTS

Nine patients with a total of 12 tumors were included, 7 patients with locally recurrent sarcoma. Three patients received neoadjuvant radiotherapy and three other patients received neoadjuvant systemic treatment. The median tumor size was 4.6 cm (2.4-10.4). The majority of distances from tumor to critical anatomical structures was <0.5 cm. The tumors were localized using the navigation system without technical or safety issues. Despite the challenging nature of these resections, 89% were R0 resections, with a median blood loss of 100 ml (20-1050) and one incident of vascular damage. Based on the survey, surgeons stated navigation resulted in shorter surgery time and made the resections easier.

CONCLUSION

Electromagnetic navigation facilitates resections of challenging lower intra-abdominal/pelvic STS and might be of added value.

Computer Navigation and 3D Printing in the Surgical Management of Bone Sarcoma

The long-term outcomes of osteosarcoma have improved; however, patients with metastases, recurrence or axial disease continue to have a poor prognosis. Computer navigation in surgery is becoming ever more commonplace, and the proposed advantages, including precision during surgery, is particularly applicable to the field of orthopaedic oncology and challenging areas such as the axial skeleton. Within this article, we provide an overview of the field of computer navigation and computer-assisted tumour surgery (CATS), in particular its relevance to the surgical management of osteosarcoma.

Assessment of Resection Margins in Bone Tumor Surgery

Limb salvage surgery is now the preferred procedure for bone tumor surgery. To decrease the risk of local recurrence, it is crucial to obtain adequate resection margins. The obtained margins must be evaluated postoperatively because they influence what treatment is given subsequently when margins are not adequate (e.g., surgical revision and radiotherapy). The study aims to evaluate margin assessment of tumor specimen by MRI compared to conventional histology (to establish the viability of using MRI) and assess the accuracy of a patient-specific instrument when narrow margins were aimed. The resection margins in 12 consecutive patients that were operated on for bone tumor resection were prospectively analyzed using three methods: MRI of the resection specimen, macroscopic evaluation of specimen slices, and microscopic pathological evaluation. The assessments were qualitative (R0, R1, and R2) and quantitative (distance in mm). MRI, macroscopic, and microscopic margins generated similar results for both the qualitative (all resections were R0) and quantitative assessments. The median error in safe margins was 2 mm with a surgical guide (PSI) and 5 mm without a surgical guide. Local recurrences were not detected after a mean follow-up period of 3.7 years (range, 2.1-5 years); however, four patients died during the study. In conclusion, MRI is a valuable tool for assessing safe margins. When specimens are not available for pathological assessment (e.g., extracorporeally irradiated autograft or autoclaved autograft), MRI could be used to evaluate margins. In particular, when tumor volume is high, MRI could also help to focus the pathological examination on areas of concern.

Team Approach: Oncologic Sacrectomy

Oncologic sacrectomy is used in the curative treatment of patients with primary sacral malignancies or select locally invasive visceral malignancies. A systematic surgical approach involves preoperative imaging, diagnosis, and multidisciplinary surgical execution. Close collaboration with pediatric, medical, and radiation oncology colleagues is often necessary to individualize treatment plans.

Computer assistance in hip preservation surgery-current status and introduction of our system

INTRODUCTION

Preservation surgery of the hip with open or arthroscopic approach has always been challenging as complex 3-D anatomy and limited surgical access make intraoperative evaluation difficult. Recent advances in computer technology offer a wide range of innovative solutions with a goal to improve accuracy and safety of corrective procedures on human joints.

METHOD

The author critically reviews currently available literature in the field of computer assistance in hip preservation surgery. Basic features of unique planning software and navigation surgical system used in treatment of femoroacetabular impingement and hip dysplasia are introduced.

RESULTS

Currently available software provides preoperative identification of hip deformity on CT-based 3-D model and planning of the surgical correction using kinematic protocols. Real-time intraoperative 3-D orientation is possible, and execution of surgical correction can be performed either with navigation of surgical tools or with printed templates. Computer assistance in hip preservation surgery is in the developing phase. First clinical experiences of its use in treatment of femoroacetabular impingement, hip dysplasia, hip tumors, and avascular necrosis of the femoral head are promising.

CONCLUSION

Computer assistance has been applied for treatment of several hip disorders. Technical advances are suggested and quality basic studies and clinical trials are encouraged for the novel technology to become more user friendly and widely accepted.

Computer navigation assisted tumor surgery for internal hemipelvectomy - Early experience

Internal hemipelvectomy is a surgically challenging entity, owing, among other reasons, to a complex anatomy. The apprehension of an inadequate margin or injury to critical structures adds to the complexity of these major surgical procedures. Computer assisted tumor surgery (CATS) has been increasingly used to improve outcomes of internal hemipelvectomy over the last decade. We analyzed the surgical and postoperative details of first four patients undergoing internal hemipelvectomy with CATS assistance at our institute, the first ever report in an Indian setting. The patients were analyzed for blood loss (mean 1300 ml), operative time (mean 306 min) and hospital stay (mean 7 days). The histopathological margins were free of disease in all the patients, even as the average closest bony margin was 0.9 cm. Sparing of sacral nerve root was made possible by the close yet free margins in two patients. In this retrospective analysis of a small series of patients with computer navigation assisted internal hemipelvectomy, we found this technique to be feasible and effective in achieving the oncological aim of negative margins with preservation of critical structures.

Intraoperative ultrasonography-guided surgery for malignant soft tissue tumor

BACKGROUND AND OBJECTIVES

A clear surgical margin is crucial for preventing the recurrence of soft tissue sarcomas (STSs). Recognizing the tumor border is difficult when the STS is impalpable or ill-defined. Ultrasonography (US) is a widely used diagnostic device that can visualize certain tumors intraoperatively. However, its usefulness for intraoperatively assessing STSs is unclear and was investigated here.

METHODS

Our study comprised 19 patients with STSs that were impalpable, ill-defined, or beneath the fascia. All patients underwent intraoperative US (IOUS), with follow-up times ranging from 5 to 103 months (mean, 49 months).

RESULTS

The mean age of the study participants was 56 years (range, 25-83 months). The most common histological diagnosis was undifferentiated pleomorphic sarcoma (UPS) (nine patients). The mean tumor size was 51 mm (range, 7-126 mm). According to the residual tumor classification, 18 tumors were microscopically negative (R0), including seven close to the fascia, and one was microscopically positive (R1). Local recurrence occurred in two cases (both classified as R0). The recurrence-free survival rate was 88.9% in 5 years.

CONCLUSIONS

IOUS-guided surgery is useful for visualizing STSs. Using this technique, STSs can be precisely localized, evaluated, and excised.

Management and retrospective analysis of pelvic ramus tumors and tumor-like lesions: Evaluation with 31 cases

OBJECTIVES

This study aims to investigate the characterization, treatment approaches, and follow-up results of tumors and tumor-like lesions located in the pelvic ramus.

PATIENTS AND METHODS

Thirty-one patients (9 males, 22 females; mean age 48.9 years; range, 7 to 79 years) with benign and malignant tumors or tumor-like lesions in the pelvic ramus region treated and followed-up in our clinic between January 2005 and January 2019 were evaluated retrospectively. Surgical procedures were performed with anterior approach or inner-thigh approach. Twelve patients were diagnosed with malignant tumors, 12 patients with benign tumors, and seven patients with tumor-like lesions.

RESULTS

Seventeen patients who underwent surgical treatment were followed-up for a mean period of 61.7 months. The diameters of benign and malignant tumors were similar (p=0.425). Of all lesions, 64.5% were located in the pubis. Ischium location was significantly higher in patients with malignant lesions than tumor-like lesions. The most common complication was diffuse subcutaneous edema in the inguinal region and thigh (8.3%).

CONCLUSION

There are many different tumoral lesions in the pelvic ramus. Pelvic ramus tumors tend to settle more frequently in pubic ramus, whereas ramus ischium tumors are more likely to be malignant. In addition, the diagnosis of insufficiency fracture should be considered primarily in pathologic fractures of pubic ramus in females over 50 years of age. In the postoperative follow-up of pelvic ramus tumors, diffuse edema may occur even if there is no intraoperative vascular damage.

Can Navigation Improve the Ability to Achieve Tumor-free Margins in Pelvic and Sacral Primary Bone Sarcoma Resections? A Historically Controlled Study

BACKGROUND

Anatomic and surgical complexity make pelvic and sacral bone sarcoma resections challenging. Positive surgical margins are more likely to occur in patients with pelvic and sacral bone sarcomas than in those with extremity sarcomas and are associated with an increased likelihood of local recurrence. Intraoperative navigation techniques have been proposed to improve surgical accuracy in achieving negative margins, but available evidence is limited to experimental (laboratory) studies and small patient series. Only one small historically controlled study is available. Because we have experience with both approaches, we wanted to assess whether navigation improves our ability to achieve negative resection margins.

QUESTIONS/PURPOSES

Are navigated resections for pelvic and sacral primary bone sarcomas better able to achieve adequate surgical margins than nonnavigated resections?

METHODS

Thirty-six patients with pelvic or sacral sarcomas treated with intraoperative navigation were retrospectively compared with 34 patients undergoing resections without navigation. All patients underwent resections between 2000 and 2017 with the intention to achieve a wide margin. Patients in the navigation group underwent surgery between 2008 and 2017; during this period, all resections of pelvic and sacral primary bone sarcomas with the intention to achieve a wide margin were navigation-assisted by either CT fluoroscopy or intraoperative CT. Patients in the control group underwent surgery before 2008 (when navigation was unavailable at our institution), to avoid selection bias. We did not attempt to match patients to controls. Nonnavigated resections were performed by two senior orthopaedic surgeons (with 10 years and > 25 years of experience). Navigated resections were performed by a senior orthopaedic surgeon with much experience in surgical navigation. The primary outcome was the bone and soft-tissue surgical margin achieved, classified by a modified Enneking system. Wide margins (≥ 2 mm) and wide-contaminated margins, in which the tumor or its pseudocapsule was exposed intraoperatively but further tissue was removed to achieve wide margins, were considered adequate; marginal (0-2 mm) and intralesional margins were considered inadequate.

RESULTS

Adequate bone margins were achieved in more patients in the navigated group than in the nonnavigation group (29 of 36 patients [81%] versus 17 of 34 [50%]; odds ratio, 4.14 [95% CI, 1.43-12.01]; p = 0.007). With the numbers available, we found no difference in our ability to achieve adequate soft-tissue margins between the navigation and nonnavigation group (18 of 36 patients [50%] versus 18 of 34 [54%]; odds ratio, 0.89 [95% CI, 0.35-2.27]; p = 0.995).

CONCLUSIONS

Intraoperative guidance techniques improved our ability to achieve negative bony margins when performing surgical resections in patients with pelvic and sacral primary bone sarcomas. Achieving adequate soft-tissue margins remains a challenge, and these margins do not appear to be influenced by navigation. Larger studies are needed to confirm our results, and longer followup of these patients is needed to determine if the use of navigation will improve survival or the risk of local recurrence.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Improved virtual surgical planning with 3D- multimodality image for malignant giant pelvic tumors

PURPOSE

We sought to assess the early clinical outcome of 3D-multimodality image (3DMMI)-based virtual surgical planning for resection and reconstruction of malignant giant pelvic tumors.

PATIENTS AND METHODS

In this retrospective case-control study, surgery was planned and performed with 3DMMI-based patient-specific instruments (PSI) in 13 patients with giant pelvic malignancy and without 3DMMI-based PSI in the other 13 patients. In the 3DMMI group, 3DMMI was utilized, taking advantages of computed tomography (CT), contrast-enhanced CT angiography (CTA), contrast-enhanced magnetic resonance imaging (MRI), contrast-enhanced magnetic resonance neurography (MRN), which could reveal the whole tumor and all adjacent vital structures. Based on these 3DMMI, virtual surgical planning was conducted and the corresponding PSI was then designed. The median follow-up was 8 (3-24) months. The median age at operation was 37.5 (17-64) years. The mean tumor size in maximum diameter was 13.3 cm. Surgical margins, intraoperative and postoperative complications, duration of surgery, and intra-operative blood loss were analyzed.

RESULTS

In the non-3DMMI group, the margins were wide in six patients (6/13), marginal in four (4/13), wide-contaminated in two (2/13), and intralesional in one (1/13). In the 3DMMI group, the margins were wide in 10 patients (10/13), marginal in three (3/13), and there were no wide-contaminated or intralesional margins. The 3DMMI group achieved shorter duration of surgery (P=0.354) and lower intraoperative blood loss (P=0.044) than the non-3DMMI group. Conclusion: The 3DMMI-based technique is advantageous to obtain negative surgical margin and decrease surgical complications related to critical structures injury for malignant giant pelvic tumor.