Navigation in Musculoskeletal Oncology: An Overview

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.

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.

Pelvic bone sarcomas, prognostic factors, and treatment: A narrative review of the literature

Primary sarcomas of bone are rare malignant mesenchymal tumors. The most common bone sarcomas are osteosarcoma, Ewing's sarcoma, and chondrosarcoma. The prognosis has improved over the years, but bone sarcomas are still life-threatening tumors that need a multidisciplinary approach for diagnosis and treatment. Bone sarcomas arising in the pelvis present a unique challenge to orthopedic oncologists due to the absence of natural anatomical barriers, the close proximity of vital neurovascular structures, and the high mechanical demands placed on any pelvic reconstruction following the excision of the tumor. While radiotherapy has an important role especially in Ewing's sarcoma and chemotherapy for both Ewing's sarcoma and osteosarcoma, surgery remains the main choice of treatment for all three entities. While external hemipelvectomy has remained one option, the main aim of surgery is limb salvage. After complete tumor resection, the bone defect needs to be reconstructed. Possibilities to reconstruct the defect include prosthetic or biological reconstruction. The method of reconstruction is dependent on the location of tumor and the surgery required for its removal. The aim of this article is to give an insight into pelvic bone sarcomas, their oncological and surgical outcomes, and the options for treatment based on the authors' experiences.

Fluorescence guidance improves the accuracy of radiological imaging-guided surgical navigation

BACKGROUND

Imaging-based navigation technologies require static referencing between the target anatomy and the optical sensors. Imaging-based navigation is therefore well suited to operations involving bony anatomy; however, these technologies have not translated to soft-tissue surgery. We sought to determine if fluorescence imaging complement conventional, radiological imaging-based navigation to guide the dissection of soft-tissue phantom tumors.

METHODS

Using a human tissue-simulating model, we created tumor phantoms with physiologically accurate optical density and contrast concentrations. Phantoms were dissected using all possible combinations of computed tomography (CT), magnetic resonance, and fluorescence imaging; controls were included. The data were margin accuracy, margin status, tumor spatial alignment, and dissection duration.

RESULTS

Margin accuracy was higher for combined navigation modalities compared to individual navigation modalities, and accuracy was highest with combined CT and fluorescence navigation (p = 0.045). Margin status improved with combined CT and fluorescence imaging.

CONCLUSIONS

At present, imaging-based navigation has limited application in guiding soft-tissue tumor operations due to its inability to compensate for positional changes during surgery. This study indicates that fluorescence guidance enhances the accuracy of imaging-based navigation and may be best viewed as a synergistic technology, rather than a competing one.

The role of patient advocates and sarcoma community initiatives in musculoskeletal oncology. Moving towards Evidence-Based Advocacy to empower Evidence-Based Medicine

Musculoskeletal sarcomas are rare cancers that as the whole family of sarcomas pose several challenges at different levels, ranging from medical knowledge to clinical research and policymaking. Addressing these challenges, necessarily calls for the inclusion of patient perspective inside the decision-making processes of every area that contributes to treatment improvement, from the provision of high-quality services by healthcare organisations to research issues. Without patient-provided inputs to inform decisions, the current paradigm of patient-centred care makes no sense and sounds at the least irrational if not unethical. Putting PROMs on "centre stage" in cancer research and care, could allow to build a truly Evidence Based Advocacy (EBA) and therefore to empower Evidence Based Medicine (EBM).

Fifty years of bone tumors

There have been enormous advances in the treatment of bone tumors over the past half-century. The most notable of these has been the transition from amputation as the standard of care to limb salvage surgery. This transition is the result of advances in imaging techniques, accurate diagnosis, systemic therapies (including chemotherapy), and prosthetic design for the reconstruction of musculoskeletal defects. Advances have also been made in the management of benign and metastatic bone tumors.

The role of imaging in computer assisted tumor surgery of the sacrum and pelvis

The use of a navigation system allows precise resection of a tumor and accurate reconstruction of the resultant defect thereby sparing important anatomical structures and preserving function. It is an "image-based" system where the imaging (computed tomography and magnetic resonance imaging) is required to supply the software with data. The fusion of the preoperative imaging provides pre-operative information about local anatomy and extent of the tumor, so that it allows an accurate preoperative planning. Accurate pre-operative imaging is mandatory in order to minimize CATS errors, thus performing accurate tumor resections.

Inhibitory Effect of Imperatorin on the Pharmacokinetics of Diazepam In Vitro and In Vivo

Background

Diazepam is a benzodiazepine drug used to treat anxiety, insomnia, and muscle spasms. Imperatorin is a phytochemical isolated from medicinal plants and is widely used in herbal medicine. The aim of this study was to investigate the interactions between imperatorin and diazepam in vitro and in vivo and to provide evidence-based guidance for the safe clinical use of the drug.

Methods

In vitro inhibition of imperatorin was assessed by incubating rat liver microsomes with diazepam to determine IC₅₀ values and the type of inhibition. For in vivo assessment, six rats were pretreated with 50 mg/kg imperatorin for two weeks, six were administered saline, and a single dose of 10 mg/kg diazepam was administered orally to both groups 30 min after the administration of imperatorin.

Results

Imperatorin inhibited the in vitro metabolism of diazepam via the competitive mechanism of CYP450. The IC₅₀ values of imperatorin to nordazepam and temazepam were 1.54 μM and 1.80 μM, respectively. The inhibitory constant values for temazepam and nordazepam were 1.24 μM and 1.29 μM, respectively. Long-term administration of imperatorin significantly increased the AUC_(0-12h), AUC_(0-∞), and Cmax of diazepam, while Vz/F and CLz/F were decreased significantly (P < 0.05). In turn, the AUC_(0-12h), AUC_(0-∞), and Cmax of nordazepam and temazepam decreased significantly, and Vz/F and CLz/F increased significantly (P < 0.05).

Conclusions

This study demonstrates that imperatorin inhibits the metabolism of diazepam both in vitro and in vivo. These results indicated that more attention should be paid when taking diazepam together with food or herbs containing IMP, although further investigation is still needed.

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.

Sacroiliac joint cut accuracy: Comparing new technologies in an idealized sawbones model

BACKGROUND AND OBJECTIVES

The anatomical complexity of the pelvis creates challenges for orthopaedic oncologists to accurately and safely resect tumors involving the sacroiliac joint. Current technology may help overcome these obstacles.

METHODS

Four fellowship-trained orthopaedic oncologists performed 22 all-posterior sacroiliac cuts using freehand, computerized navigation, and patient-specific cutting guides on a Sawbones male pelvis model. Cut accuracies to preoperative planned margins were analyzed via a high-resolution optical scanner. Soft tissue damage was determined by visually inspecting the Sawbones foam placed on the far side of the cut.

RESULTS

Within 5 mm of the margins, the freehand technique resulted in 67.0% cut accuracy, the navigation technique had 71.1%, and the patient-specific cutting guide technique had 85.6% (P = .093). Within 2 mm, the techniques showed an accuracy of 25.8%, 32.5%, and 47.5%, respectively (P = .022). Regarding soft tissue damage, the freehand technique exhibited minimal penetration damage for 16.7% of the cuts, while navigation and patient-specific guide techniques exhibited 25.0% and 75.0%, respectively (P = .046). Years of surgical experience of the operator (1-7) did not influence the cut accuracy for any method.

CONCLUSIONS

Under ideal conditions, patient-specific guide technology possesses the same or better accuracy as other cutting techniques as well as the circumvention of soft tissue damage.

Use of three-dimensional printing and intraoperative navigation in the surgical resection of metastatic acetabular osteosarcoma

A 21-year-old man underwent a joint-preserving posterior acetabular resection of metastatic osteosarcoma using a three-dimensional (3D) printed model and intraoperative navigation. The combined application of these advanced technologies can allow for surgical planning of osteotomies involving complex anatomy and help guide resections intraoperatively. They can maximise the achievement of negative oncological margins, preservation of native hip stability and critical neurovascular structures, and optimal postoperative function in an effort to resect all clinically evident disease. For this particular patient, with secondary bony metastases, they allowed for a safe and well-tolerated procedure that ultimately afforded him palliative benefit, improved quality of life and, conceivably, prolonged survival in the setting of a devastating prognosis. Although he, sadly, has since passed away, he survived for over 2 years after initial metastasis with preserved hip stability and the ability to graduate college, stay active and maintain a quality of life that addressed his goals of care.

The evolution of three-dimensional technology in musculoskeletal oncology

Musculoskeletal tumours pose considerable challenges for the orthopaedic surgeon during pre-operative planning, resection and reconstruction. Improvements in imaging technology have improved the diagnostic process of these tumours. Despite this, studies have highlighted the difficulties in achieving consistent resection free margins especially in tumours of the pelvis and spine when using conventional methods. Three-dimensional technology - three-dimensional printing and navigation technology - while relatively new, may have the potential to prove useful in the musculoskeletal tumour surgeon's arsenal. Three-dimensional printing (3DP) allows the production of objects by adding material layer by layer rather than subtraction from raw materials as performed conventionally. High resolution imaging, computer tomography (CT) and magnetic resonance imaging (MRI), are used to print highly complex and accurate items. Powder-based printing, vat polymerization-based printing and droplet-based printing are the common 3DP technologies applied. 3DP has been utilized pre-operatively in surgical planning and intra-operatively for patient specific instruments and custom made prosthesis. Pre-operative 3DP models transfer information to the surgeon in a concise yet exhaustive manner. Patient specific instruments are customized 3DP instruments utilized with the intention to easily replicate surgical plans. Complex musculoskeletal tumours pose reconstructive challenges and standard implants are often unable to reconstruct defects satisfactorily. The ability to use custom materials and tailor the pore size, elastic modulus and porosity of the 3DP prosthesis to be comparable to the patient's bone allows for a potential patient-specific prosthesis with unique incorporation and longevity properties. Similarly, navigation technology utilizes CT or MRI images to provides surgeons with real time intraoperative three-dimensional calibration of instruments. It has been shown to potentially allow surgeons to perform more accurate resections. These technological advancements have the potential to greatly impact the management of musculoskeletal tumours. 3D planning models, patient-specific instruments and customized 3DP implants and navigation should not be thought of as separate, but rather, patient-specific adaptation of relevant modes of application should be selected on a case-by-case basis when taking all unique factors of each case into consideration.