Mixed Reality Improves 3D Visualization and Spatial Awareness of Bone Tumors for Surgical Planning in Orthopaedic Oncology: A Proof of Concept Study.

Introduction: In orthopedic oncology, computer navigation and 3D-printed guides facilitate precise osteotomies only after surgical exposure. Before surgeries start, it is challenging to mentally process and superimpose the virtual medical images onto patients' anatomy for preoperative surgical planning. Mixed Reality (MR) is an immersive technology merging real and virtual worlds, and users can interact with digital objects in real time. Through Head-Mounted Displays, surgeons directly visualize holographic models that overlaid on tumor patients. The technology may facilitate surgical planning before skin incisions. Methods: Nine bone tumor patients were included (July 2021 - Dec 2022). There were six primary bone sarcomas, two benign bone tumors, and one revision pelvic prosthesis. MR applications were created using patients' preoperative medical images. The surgeon examined each patient clinically using the conventional method of viewing 2D images and MR via HMD, Hololens 2. A Likert-Scale (LS) questionnaire and The National Aeronautics and Space Administration-Task Load Index (NASA-TLX) score were used to evaluate and compare the effectiveness of surgical planning and the surgeon's clinical cognitive workload for the two methods. Results: The qualitative survey of the LS questionnaire suggested that the MR group had superior spatial awareness of tumors and was considered more effective as a preoperative planning tool than the conventional group. For NASA-TLX scores, the overall cognitive workload was lower in MR 3D hologram group than in the 2D Group for preoperative clinical assessment. When using MR technology with HMDs, the surgeon reported no discomfort. Conclusion: MR technology may improve 3D visualization and spatial awareness of bone tumors in patients' anatomies and may facilitate surgical planning before skin incisions in orthopedic oncology surgery. With less cognitive load and better ergonomics, surgeons can focus on patients and surgical tasks with MR technology. Further studies must investigate whether MR technology improves clinical outcomes.

Associations between Lifestyle Factors and Neurocognitive Impairment among Chinese Adolescent and Young Adult (AYA) Survivors of Sarcoma.

BACKGROUND: The effect of lifestyle on neurocognitive impairment among cancer survivors remain an understudied area. This study explored the association between lifestyle factors and neurocognitive outcomes (specifically, attention, memory, processing speed and cognitive flexibility) in AYA survivors (aged 15-39 years) of sarcoma. METHODS: This study recruited 116 AYA survivors (age 28.2 (SD = 8.2) years), who were diagnosed with osteosarcoma (49%) or soft-tissue sarcoma (51%) at age 13.3 (SD = 7.2) years. The neurocognitive battery included measures of attention, memory, motor-processing speed, and cognitive flexibility. Survivors reported health-damaging practices, which included: physical inactivity, smoking, alcohol intake, inadequate sleep (<7 h of actual sleep/day), sleep-related fatigue (Multidimensional Fatigue Scale) and long working hours (>9 h/day). General linear modeling was conducted to examine the association between lifestyle factors and neurocognitive outcomes, adjusting for age at diagnosis, sex, education attainment and clinical/treatment variables. RESULTS: At 14.9 (SD = 7.6) years post-diagnosis, survivors demonstrated impairment in attentiveness (4.3-13.0%), processing speed (34.5%) and cognitive flexibility (18.1%). Nearly half (45.7%) had developed a chronic health condition (CHC). Low physical activity (estimate = -0.97, p = 0.003) and sleep-related fatigue (estimate = -0.08, p = 0.005) were associated with inattention. Survivors who worked >9 h/day (n = 15) demonstrated worse attention (estimate = 5.42, p = 0.023) and cognitive flexibility (estimate = 5.22, p = 0.005) than survivors who worked ≤9 h/day (n = 66). Interaction analysis (CHCs*physical activity) showed that survivors who developed CHCs and reported low physical activity had worse attention (p = 0.032) and cognitive-flexibility (p = 0.019) scores than other subgroups. CONCLUSION: Treatment-related CHCs, coupled with continued physical inactivity, may exacerbate inattention and executive dysfunction among survivors. Long working hours and sleep-related fatigue are associated with worse functioning; this finding should be validated with prospective assessment of work-related stressors and objective sleep measures.

Intermediate-term results and risk factors analysis of tumor endoprosthesis in paediatric patients after the resection of lower extremity bone sarcoma.

BACKGROUND: Mechanical failure of the endoprostheses is a concern in paediatric patients with primary bone sarcoma. Their long-term results are variable in the Asian population, thus we aim to investigate the outcome by assessing the mechanical failure, its risk factors and the functional results. METHODS: We retrospectively reviewed 38 paediatric patients (mean 13.29, range 6-18) with primary bone sarcoma of lower extremity undergone chemotherapy and limb salvage surgery with tumor endoprosthesis between 2003 and 2016. All hospital notes were reviewed for any type of failures. Risk factors for implant loosening like stem size, remaining bone length, stem length, extracortical bone bridge ingrowth (EBBI), the ratio of resected bone length to whole bone length, bone stem ratio and custom-made versus modular were analyzed. The limb function was recorded by Musculoskeletal Tumor Society (MSTS) score. Median follow-up time was 7.42 years (3.0-15.4 years) and minimum follow-up for surviving patients was 2 years. RESULTS: Endoprosthesis survivorship, according to Kaplan Meier was 94.7%, 85.4% and 66.2% at 2, 5 and 10 years respectively. Type II failure occurred in three patients (7.9%). Type III failure occurred in four patients (10.5%). Type IV failure occured in two patients (5.2%). Only EBBI independently predicted implant loosening (p = .007). Risk factors like stem size, remaining bone length, stem length, the ratio of resected bone length to whole bone length and custom-made versus modular were not associated with increase in implant loosening (p > .05). The mean stem size was 9.41 mm in asymptomatic group, comparable with 9.22 mm in the failure group (p = .79). The MSTS score was 29.62. CONCLUSIONS: Our data suggests that paediatric Chinese patients with small body built had good and excellent mid-term results in implant survival and limb function respectively. EBBI is important in preventing loosening in tumor endoprosthesis. In contrast to the reported higher failure risk with stem size <12 mm, we found no increased loosening rate with smaller stem size endoprosthesis. LEVEL OF EVIDENCE: Class III.

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.

Development of deep learning algorithms to discriminate giant cell tumors of bone from adjacent normal tissues by confocal Raman spectroscopy.

Raman spectroscopy is a non-destructive analysis technique that provides detailed information about the chemical structure of tumors. Raman spectra of 52 giant cell tumors of bone (GCTB) and 21 adjacent normal tissues of formalin-fixed paraffin embedded (FFPE) and frozen specimens were obtained using a confocal Raman spectrometer and analyzed with machine learning and deep learning algorithms. We discovered characteristic Raman shifts in the GCTB specimens. They were assigned to phenylalanine and tyrosine. Based on the spectroscopic data, classification algorithms including support vector machine, k-nearest neighbors and long short-term memory (LSTM) were successfully applied to discriminate GCTB from adjacent normal tissues of both the FFPE and frozen specimens, with the accuracy ranging from 82.8% to 94.5%. Importantly, our LSTM algorithm showed the best performance in the discrimination of the frozen specimens, with a sensitivity and specificity of 93.9% and 95.1% respectively, and the AUC was 0.97. The results of our study suggest that confocal Raman spectroscopy accomplished by the LSTM network could non-destructively evaluate a tumor margin by its inherent biochemical specificity which may allow intraoperative assessment of the adequacy of tumor clearance.

3D printing in orthopaedic surgery: a scoping review of randomized controlled trials.

AIMS: The use of 3D printing has become increasingly popular and has been widely used in orthopaedic surgery. There has been a trend towards an increasing number of publications in this field, but existing literature incorporates limited high-quality studies, and there is a lack of reports on outcomes. The aim of this study was to perform a scoping review with Level I evidence on the application and effectiveness of 3D printing. METHODS: A literature search was performed in PubMed, Embase, and Web of Science databases. The keywords used for the search criteria were ((3d print*) OR (rapid prototyp*) OR (additive manufactur*)) AND (orthopaedic). The inclusion criteria were: 1) use of 3D printing in orthopaedics, 2) randomized controlled trials, and 3) studies with participants/patients. Risk of bias was assessed with Cochrane Collaboration Tool and PEDro Score. Pooled analysis was performed. RESULTS: Overall, 21 studies were included in our study with a pooled total of 932 participants. Pooled analysis showed that operating time (p < 0.001), blood loss (p < 0.001), fluoroscopy times (p < 0.001), bone union time (p < 0.001), pain (p = 0.040), accuracy (p < 0.001), and functional scores (p < 0.001) were significantly improved with 3D printing compared to the control group. There were no significant differences in complications. CONCLUSION: 3D printing is a rapidly developing field in orthopaedics. Our findings show that 3D printing is advantageous in terms of operating time, blood loss, fluoroscopy times, bone union time, pain, accuracy, and function. The use of 3D printing did not increase the risk of complications. Cite this article: Bone Joint Res 2021;10(12):807-819.

Complex joint-preserving bone tumor resection and reconstruction using computer navigation and 3D-printed patient-specific guides: A technical note of three cases.

In selected extremity bone sarcomas, joint-preserving surgery retains the natural joints and nearby ligaments with a better function than in traditional joint-sacrificing surgery. Geometric multiplanar osteotomies around bone sarcomas were reported with the advantage of preserving more host bone. However, the complex surgical planning translation to the operating room is challenging. Using both Computer Navigation and Patient-Specific Guide may combine each technique's key advantage in assisting complex bone tumor resections. Computer Navigation provides the visual image feedback of the pathological information and validates the correct placement of Patient-Specific Guide that enables accurate, guided bone resections. We first described the digital workflow and the use of both computer navigation and patient-specific guides (NAVIG) to assist the multiplanar osteotomies in three extremity bone sarcoma patients who underwent joint-preserving bone tumor resections and reconstruction with patient-specific implants. The NAVIG technique verified the correct placement of patient-specific guides that enabled precise osteotomies and well-fitted patient-specific implants. The mean maximum deviation errors of the nine achieved bone resections were 1.64 â€‹± â€‹0.35 â€‹mm (95% CI 1.29 to 1.99). The histological examination of the tumor specimens showed negative resection margin. At the mean follow-up of 55 months (40-67), no local recurrence was noted. There was no implant loosening that needed revision. The mean MSTS score was 29 (28-30) out of 30 with the mean knee flexion of 140° (130°-150°). The excellent surgical accuracy and limb function suggested that the NAVIG technique might replicate the surgical planning of complex bone sarcoma resections by combining the strength of both Computer Navigation and Patient-Specific Guide. The patient-specific approach may translate into clinical benefits. The translational potential of this article: The newly described technique enhances surgeons' capability in performing complex joint-preserving surgery in bone sarcoma that is difficult to be achieved by the traditional method. The high precision and accuracy may translate into superior clinical outcomes.

Long-term outcome of vascularized iliac bone grafting for osteonecrosis of femoral head: A retrospective study with 17-year follow-up.

AIMS: This study aims to investigate the long-term results of vascularized iliac bone grafting (VIBG) for osteonecrosis of the femoral head (ONFH). The primary outcome is the long-term survivorship of VIBG, using conversion to total hip arthroplasty as an end-point. Secondly, this study will also analyse the patient or disease factors influencing the long-term survivorship of VIBG. METHODS: Forty-two patients (50 hips) underwent VIBG for ONFH in our institute between September 1995 and November 2013. Only patients with a follow-up of at least 5 years were included. The risk factors, surgical complications and VIBG survivorship were recorded. The stage of ONFH was classified according to the Ficat staging of the pre-operative radiographs. VIBG was only performed to patients with ONFH of Ficat stage II and stage III. Patients with hip arthritis (Ficat stage IV) did not receive VIBG and thus excluded from the study. Long-term survivorship of VIBG is measured by conversion to total hip arthroplasty. RESULTS: Twenty-eight hips (56%) had surviving VIBG for the duration of follow-up. The overall mean graft survival was 12.2 ± 7.8 years (0.4-24.0). Steroid and alcohol-induced osteonecrosis were more predominant in the graft-failure group, which had a hazard ratio of 2.33 and 2.07 respectively for graft failure (p = 0.047). In terms of complication, there was one case of groin wound infection which required surgical debridement. CONCLUSION: At a long-term follow-up of 17 years, our results showed that VIBG is effective in treating patients with pre-collapse (Ficat Stage II) and early post-collapse (Ficat stage III) in ONFH. Alcoholics and patients with steroid are at a higher risk of graft failure, so VIBG should be performed cautiously in these patients. VIBG is an intermediate operation until osteoarthritis sets in, either by the progression of ONFH or natural degenerative change.

Local Recurrence After Minimally Invasive Curettage For Primary Giant Cell Tumor of Bone With Perioperative Bisphosphonate Is Comparable to Open Curettage: Retrospective Comparison With 9-Year Follow-Up.

PURPOSE: To compare the long-term oncological outcome of minimally invasive curettage (MIC) with conventional open curettage (OC). METHODS: We studied patients with primary giant cell tumor of bone (GCTB) of extremities who underwent intralesional tumor curettage and cementation and perioperative bisphosphonates from February 2003 to June 2016. All cases were histology-confirmed diagnoses of GCTB. Recurrent GCTB, malignant GCTB, cases in the axial skeleton (pelvis and spine), or cases with bone grafting of the curetted cavity were excluded. The local recurrence-free (LR-free) estimates of the OC and MIC groups were compared. The hazard ratio of a local recurrence was calculated for the various factors of the patients, disease, and treatment. RESULTS: At a mean follow-up of 8.8 years, the overall LR rate was 24.2% (8 out of 33 patients). There was no statistical difference in LR in MIC and OC groups (27.8 % vs 20%; P = .6). The mean time to LR was 33.1 months (8 to 75). The operative time was comparable in both MIC and OC groups. None of the risk factors studied led to a significantly higher hazard of LR. CONCLUSIONS: At a long-term follow-up of 9 years, MIC showed similar LR-free survival to OC. Combining bisphosphonates and MIC with a less invasive approach showed reasonable LR-free survival in long-term follow-up. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Simvastatin Possesses Antitumor and Differentiation-Promoting Properties That Affect Stromal Cells in Giant Cell Tumor of Bone.

Giant cell tumor of bone (GCTB) is a locally aggressive destructive bone lesion. The management of pulmonary metastasis and local recurrence after the surgical treatment of GCTB remains a challenge. Pathologically, stromal cells in GCTB are known as primary neoplastic cells and are recognized as incompletely differentiated preosteoblasts. Therefore, inducing GCTB stromal cells to differentiate into cells with a mature osteoblastic phenotype may stop tumor growth and recurrence. In this study, we aimed to investigate how simvastatin, a clinically approved and commonly used statin that has been known to promote the maturation of cells of the osteogenic lineage, affects GCTB stromal cells. We found that simvastatin effectively inhibited cell viability by suppressing proliferation and by inducing apoptosis in GCTB stromal cells. Moreover, simvastatin treatment upregulated the expression of genes related to osteogenic maturation, such as runt-related transcription factor 2, osteopontin, and osteocalcin, and increased the mineralization of the extracellular matrix in GCTB stromal cells. Ingenuity pathway analysis was used to discover that the vitamin D receptor pathway was involved in the simvastatin-induced osteogenic differentiation of GCTB stromal cells by upregulating the 1,25-dihydroxyvitamin D metabolism. Taken together, this in vitro study demonstrates the antitumor and differentiation-promoting effects of simvastatin on GCTB stromal cells and suggests the possibility of using simvastatin as an adjuvant therapy for GCTB. These findings support further clinical investigation of the efficacy of using simvastatin as an adjuvant therapy for GCTB to reduce recurrence and distant metastasis after surgical treatment. © 2019 Orthopedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:297-310, 2020.

Giant cell tumour of the bone treated with denosumab: How has the blood supply and oncological prognosis of the tumour changed?

BACKGROUND: Denosumab is gradually applied to refractory or unresectable giant cell tumour of the bone. Whether denosumab can effectively reduce the blood supply of tumour and bring benefit is worthy of study. The aim of the study is to evaluate the related changes after treatment: blood supply, surgical plan downstaging, surgical difficulty and oncological prognosis. METHODS: A self-case-control study was performed from June 2014 to November 2016, and 18 patients were enrolled. Patients received subcutaneous denosumab 120 mg every 4 weeks preoperatively, with additional doses administered on Days 8 and 15 during the first month of therapy. The initial treatment duration was 12 weeks. After 12 weeks treatment, enhanced CT examination was performed for evaluating whether surgical treatment was practicable. The patients received preoperative denosumab treatment for 5 (median 3, range 3-12) months in average. The microvessel density of tumour samples was calculated for evaluating tumour blood supply. The computed tomography (CT) enhancement rate was compared before and after treatment. The related changes of parameters were recorded as the following: clinical benefits, serious side effects, enhancement rate of CT, surgical plans, intraoperative blood loss, operative time, surgical difficulty, histological changes and local recurrence. The patients were followed up every 3 months postoperatively. RESULTS: The average CT enhancement rate of lesions was 2.08 and 1.40 before and after treatment (p = 0.000), respectively. The unenhanced CT value was significantly increased after treatment (p = 0.038). The CT enhancement rate changed more significantly in pelvic or sacral lesions than that in limb lesions (p = 0.024). Sixteen cases underwent final surgery, and surgical plan was downstaged. The histological examination showed tumour cells were significantly reduced or even disappeared after treatment. The microvessel density decreased significantly after treatment. The mean postoperative follow-up was 18.8 (10-31) months, and five patients had local recurrence. The high local recurrence rate (4/6) in sacral tumours may be related to the increased difficulty of curettage. CONCLUSION: Denosumab treatment can reduce the blood supply of giant cell tumour. The sacral or pelvic lesions changed more significantly than limb lesions. The surgical plan downstaging can also be achieved. The clear margin after denosumab treatment facilitated tumour resection but, increased difficult in curettage surgery, and high recurrence rate of sacral tumour is being concerned. THE TRANSLATIONAL IMPACT OF THIS ARTICLE: Denosumab is a new type of humanized monoclonal antibody which showed some effect in the treatment giant cell tumor of bone. Pre-operative treatment with denosamub can reduce intra-operative blood loss and down-stage surgical plan in suitable cases.

PRRX-NCOA1/2 rearrangement characterizes a distinctive fibroblastic neoplasm.

Fibroblastic/myofibroblastic neoplasms represent a broad, and occasionally diagnostically challenging, category of soft tissue neoplasms. A subset of these tumors defy conventional classification. However, with the advent of next-generation sequencing, the identification of disease-defining molecular alterations is gradually improving their subclassification. Following identification of two index cases of a distinctive fibroblastic neoplasm with a fusion gene involving PRRX1 and NCOA1, we performed a retrospective review to further characterize this entity. We identified two additional cases, including one with a fusion between PRRX1 and NCOA2. The average patient age was 38 years, and three patients were female. Two tumors occurred on the neck, and the others involved the groin and thigh. Tumors were centered in the subcutis and ranged from 2.3 to 14.0 cm (average 5.8 cm). Morphologically, they were predominantly hypocellular, with focal hypercellularity. They were composed of monomorphic spindle-stellate cells with a vague fascicular pattern. The nuclei were bland with only rare mitotic activity, and occasional multinucleation. The intervening stroma was typically abundant and ranged from myxoid to collagenous, with frequent rope-like collagen bundles. Three of the cases had a prominent vasculature ranging from numerous small curvilinear vessels to ectatic and branching staghorn-like vessels. Immunohistochemistry was negative for desmin, smooth muscle actin, S100, CD34, keratin, and epithelial membrane antigen. Each of the patients was treated by simple excision and none of the tumors were associated with local recurrence or metastasis. Based on their unique morphological and molecular attributes, we believe this represents a novel fibroblastic tumor for which we have tentatively proposed the name "PRRX-NCOAx-rearranged fibroblastic tumor."

A Cadaveric Comparative Study on the Surgical Accuracy of Freehand, Computer Navigation, and Patient-Specific Instruments in Joint-Preserving Bone Tumor Resections.

Orthopedic oncologic surgery requires preservation of a functioning limb at the essence of achieving safe margins. With most bone sarcomas arising from the metaphyseal region, in close proximity to joints, joint-salvage surgery can be challenging. Intraoperative guidance techniques like computer-assisted surgery (CAS) and patient-specific instrumentation (PSI) could assist in achieving higher surgical accuracy. This study investigates the surgical accuracy of freehand, CAS- and PSI-assisted joint-preserving tumor resections and tests whether integration of CAS with PSI (CAS + PSI) can further improve accuracy. CT scans of 16 simulated tumors around the knee in four human cadavers were performed and imported into engineering software (MIMICS) for 3D planning of multiplanar joint-preserving resections. The planned resections were transferred to the navigation system and/or used for PSI design. Location accuracy (LA), entry and exit points of all 56 planes, and resection time were measured by postprocedural CT. Both CAS + PSI- and PSI-assisted techniques could reproduce planned resections with a mean LA of less than 2 mm. There was no statistical difference in LA between CAS + PSI and PSI resections (p=0.92), but both CAS + PSI and PSI showed a significantly higher LA compared to CAS (p=0.042 and p=0.034, respectively). PSI-assisted resections were faster compared to CAS + PSI (p < 0.001) and CAS (p < 0.001). Adding CAS to PSI did improve the exit points, however not significantly. In conclusion, PSI showed the best overall surgical accuracy and is fastest and easy to use. CAS could be used as an intraoperative quality control tool for PSI, and integration of CAS with PSI is possible but did not improve surgical accuracy. Both CAS and PSI seem complementary in improving surgical accuracy and are not mutually exclusive. Image-based techniques like CAS and PSI are superior over freehand resection. Surgeons should choose the technique most suitable based on the patient and tumor specifics.

Computer Navigation in Orthopaedic Tumour Surgery.

In orthopaedic bone tumour surgery, surgeons perform malignant bone tumour resections with tumour-free margin. The bone defects following the resections have to be reconstructed to restore limb function. An inaccurate resection with positive surgical margin increased the risk of local recurrence and compromised patients' survival. Conventionally, orthopaedic tumour surgeons analyse two-dimensional (2D) imaging information and mentally integrate to formulate a three-dimensional (3D) surgical plan. It is difficult to translate the surgical plan to the operating room in complex cases.Computer-assisted tumour surgery (CATS) has been developed in orthopaedic oncology for the last decade. The technique may enable surgeons' 3D surgical planning and image-guided bone resection as planned. The technique may apply to difficult surgery in pelvic or sacral tumours, limited resection in joint-preserving tumour surgery or bone defect reconstruction using CAD prostheses or allograft.Early results suggested that the technique may help in safe tumour resection and improve surgical accuracy by replicating the preoperative planning. The improved surgical accuracy may offer clinical benefits.Surgeons have to be aware of the potential errors of the technique that may result in inaccurate bone resections with possible adverse clinical outcomes. Given that bone sarcoma is rare, the published reports from different tumour centres could only analyse relatively small patient population with the heterogeneous histological diagnosis. Multicentre comparative studies with long-term follow-up are necessary to confirm its clinical efficacy.This chapter provides an overview of computer navigation in orthopaedic tumour surgery over the past decade. It (1) describes the current workflow, (2) reports the clinical indications and results and (3) discusses its limitations and future development.

Differential expression of filamin B splice variants in giant cell tumor cells.

Giant cell tumor of bone (GCT) is the most commonly reported non-malignant bone tumor in Hong Kong. This kind of tumor usually affects people aged 20-40 years. Also, it is well known for recurrence locally, especially when the tumor cannot be removed completely. Filamins are actin-binding proteins which contain three family members, filamin A, B and C. They are the products of three different genes, FLNA, FLNB and FLNC, which can generate various transcript variants in different cell types. In this study, we focused on the effects of FLNBv2 and FLNBv4 toward GCT cells. The only difference between FLNBv2 and FLNBv4 is that FLNBv4 does not contain hinge 1 region. We found that the relative abundance of FLNBv4 varies among different GCT cell lines while the expression level of FLNBv4 in normal osteoblasts was only marginally detectable. In the functional aspect, overexpression of FLNBv4 led to upregulation of RANKL, OCN, OPG and RUNX2, which are closely related to GCT cell survival and differentiation. Moreover, FLNBv4 can have a negative effect on cell viability of GCT cells when compare with FLNBv2. In conclusion, splicing variants of FLNB are differentially expressed in GCT cells and may play a role in the proliferation and differentiation of tumor cells.

Patient-specific instrument can achieve same accuracy with less resection time than navigation assistance in periacetabular pelvic tumor surgery: a cadaveric study.

PURPOSE: Inaccurate resection in pelvic tumors can result in compromised margins with increase local recurrence. Navigation-assisted and patient-specific instrument (PSI) techniques have recently been reported in assisting pelvic tumor surgery with the tendency of improving surgical accuracy. We examined and compared the accuracy of transferring a virtual pelvic resection plan to actual surgery using navigation-assisted or PSI technique in a cadaver study. METHODS: We performed CT scan in twelve cadaveric bodies including whole pelvic bones. Either supraacetabular or partial acetabular resection was virtually planned in a hemipelvis using engineering software. The virtual resection plan was transferred to a CT-based navigation system or was used for design and fabrication of PSI. Pelvic resections were performed using navigation assistance in six cadavers and PSI in another six. Post-resection images were co-registered with preoperative planning for comparative analysis of resection accuracy in the two techniques. RESULTS: The mean average deviation error from the planned resection was no different ([Formula: see text]) for the navigation and the PSI groups: 1.9 versus 1.4 mm, respectively. The mean time required for the bone resection was greater ([Formula: see text]) for the navigation group than for the PSI group: 16.2 versus 1.1 min, respectively. CONCLUSIONS: In simulated periacetabular pelvic tumor resections, PSI technique enabled surgeons to reproduce the virtual surgical plan with similar accuracy but with less bone resection time when compared with navigation assistance. Further studies are required to investigate the clinical benefits of PSI technique in pelvic tumor surgery.

3D-printed patient-specific applications in orthopedics.

With advances in both medical imaging and computer programming, two-dimensional axial images can be processed into other reformatted views (sagittal and coronal) and three-dimensional (3D) virtual models that represent a patients' own anatomy. This processed digital information can be analyzed in detail by orthopedic surgeons to perform patient-specific orthopedic procedures. The use of 3D printing is rising and has become more prevalent in medical applications over the last decade as surgeons and researchers are increasingly utilizing the technology's flexibility in manufacturing objects. 3D printing is a type of manufacturing process in which materials such as plastic or metal are deposited in layers to create a 3D object from a digital model. This additive manufacturing method has the advantage of fabricating objects with complex freeform geometry, which is impossible using traditional subtractive manufacturing methods. Specifically in surgical applications, the 3D printing techniques can not only generate models that give a better understanding of the complex anatomy and pathology of the patients and aid in education and surgical training, but can also produce patient-specific surgical guides or even custom implants that are tailor-made to the surgical requirements. As the clinical workflow of the 3D printing technology continues to evolve, orthopedic surgeons should embrace the latest knowledge of the technology and incorporate it into their clinical practice for patient-specific orthopedic applications. This paper is written to help orthopedic surgeons stay up-to-date on the emerging 3D technology, starting from the acquisition of clinical imaging to 3D printing for patient-specific applications in orthopedics. It 1) presents the necessary steps to prepare the medical images that are required for 3D printing, 2) reviews the current applications of 3D printing in patient-specific orthopedic procedures, 3) discusses the potential advantages and limitations of 3D-printed custom orthopedic implants, and 4) suggests the directions for future development. The 3D printing technology has been reported to be beneficial in patient-specific orthopedics, such as in the creation of anatomic models for surgical planning, education and surgical training, patient-specific instruments, and 3D-printed custom implants. Besides being anatomically conformed to a patient's surgical requirement, 3D-printed implants can be fabricated with scaffold lattices that may facilitate osteointegration and reduce implant stiffness. However, limitations including high cost of the implants, the lead time in manufacturing, and lack of intraoperative flexibility need to be addressed. New biomimetic materials have been investigated for use in 3D printing. To increase utilization of 3D printing technology in orthopedics, an all-in-one computer platform should be developed for easy planning and seamless communications among different care providers. Further studies are needed to investigate the real clinical efficacy of 3D printings in orthopedic applications.

A mouse model of luciferase-transfected stromal cells of giant cell tumor of bone.

A major barrier towards the study of the effects of drugs on Giant Cell Tumor of Bone (GCT) has been the lack of an animal model. In this study, we created an animal model in which GCT stromal cells survived and functioned as proliferating neoplastic cells. A proliferative cell line of GCT stromal cells was used to create a stable and luciferase-transduced cell line, Luc-G33. The cell line was characterized and was found that there were no significant differences on cell proliferation rate and recruitment of monocytes when compared with the wild type GCT stromal cells. We delivered the Luc-G33 cells either subcutaneously on the back or to the tibiae of the nude mice. The presence of viable Luc-G33 cells was assessed using real-time live imaging by the IVIS 200 bioluminescent imaging (BLI) system. The tumor cells initially propagated and remained viable on site for 7 weeks in the subcutaneous tumor model. We also tested in vivo antitumor effects of Zoledronate (ZOL) and Geranylgeranyl transferase-I inhibitor (GGTI-298) alone or their combinations in Luc-G33-transplanted nude mice. ZOL alone at 400 µg/kg and the co-treatment of ZOL at 400 µg/kg and GGTI-298 at 1.16 mg/kg reduced tumor cell viability in the model. Furthermore, the anti-tumor effects by ZOL, GGTI-298 and the co-treatment in subcutaneous tumor model were also confirmed by immunohistochemical (IHC) staining. In conclusion, we established a nude mice model of GCT stromal cells which allows non-invasive, real-time assessments of tumor development and testing the in vivo effects of different adjuvants for treating GCT.

Use of Computer Navigation in Orthopedic Oncology.

The use of computer navigation was first described in the surgical resection of pelvic tumors in 2004. It was developed to improve surgical accuracy with the goal of achieving clear resection margins and better oncologic results. During the past few years, there has been tremendous advancement of computer-assisted tumor surgery (CATS) in the field of orthopedic oncology. Currently, CATS with image fusion offers preoperative three-dimensional surgical planning and allows surgeons to reproduce the intended bone resections in musculoskeletal tumors. The technique is reported to be useful in technically demanding resections, such as in pelvic and sacral tumors; joint-preserving intercalated and multiplanar tumor resection; and complex reconstruction with custom computer-aided design prostheses or allografts. This article provides an up-to-date review of the recent developments and key features in CATS, its current status in clinical practice, and future directions in its development.