Diffuse-Type Tenosynovial Giant Cell Tumour Involving Bone Masquerading as Langerhans Cell Histiocytosis.

We presented a case of diffuse-type tenosynovial giant cell tumour (DTSGCT) of foot masquerading as Langerhans cell histiocytosis. Preliminary diagnosis by needle biopsy was difficult due to the major involvement of bones and the overshadowing effect of the accompanying Langerhans cells. The complete curettage specimen with relevant immunohistochemistry and molecular tests made the final diagnosis of DTSGCT possible. The biomolecular mechanism for the masquerading phenomenon was explained by CSF1 overexpression in the neoplastic cells attracting migration and proliferation of CSF1R-positive Langerhans cells.

Plate-assisted bone segment transport: Novel application on distal tibia defect after tumour resection. A case report.

INTRODUCTION: Reconstruction of a large bone defect of the distal tibia after limb salvage surgery is difficult. The options include custom-made ankle endoprosthetic replacement, arthrodesis, and biological or metallic intercalary reconstructions. This report introduces a technique that provides the patient with a long-lasting biological reconstruction while preserving the native ankle. PRESENTATION OF CASE: We present the case of a 47-year-old man with osteosarcoma of the distal tibia. After neoadjuvant chemotherapy, wide excision was performed while preserving the ankle joint. Bone reconstruction by Plate-assisted bone segment transport (PABST) was performed with a non-invasive growing intramedullary nail. At 34 months of follow-up, there was solid union and the Musculoskeletal Tumour Society Score was 26/30. DISCUSSION: This is the first report of PABST after distal tibia tumour resection. It shows that this is a viable and safe method of reconstruction. Despite the use of adjuvant chemotherapy, regenerate was formed and union was achieved. CONCLUSION: PABST is a useful tool in the armamentarium to tackle difficult large bone defects.

Vascularised bone graft is an effective technique for extracortical bone bridging to combat cemented megaprosthesis loosening at the bone-implant junction.

INTRODUCTION: The bone-implant junction is a potential site for aseptic loosening. Extracortical bone bridging at the bone-implant junction is advocated to improve implant fixation by forming a biological seal. We propose a novel technique with vascularised bone graft (VBG) to form an extracortical bone bridge at the bone-implant junction to enhance implant stability. We compared the clinical and radiological outcomes for tumour megaprostheses performed (1) with and without bone graft and (2) with non-vascularised versus VBG technique. METHODS: Forty-six tumour megaprosthesis procedures from 1 June 2007 to 31 October 2017 were identified from hospital records. Twenty-eight operations incorporated bone graft at the bone-implant junction, and 18 did not. Of these 28 bone graft procedures, 13 involved VBG, and 15 did not (non-VBG). The VBG technique involves resecting a short segment of healthy bone beyond the oncological margin with its preserved blood supply, splitting it, then securing it over the junction. Clinical outcomes assessed included loosening, fracture and recurrence. Extracortical bone growth at the bone-implant junction was quantified radiologically at intervals 0-24 months post-operatively. The mean follow-up was 4.27 years. RESULTS: There were five incidences (27.8%) of loosening in the non-bone graft group compared to zero in the bone graft group (p = 0.03). There was a higher radiological score of extracortical bone growth in the bone graft group compared to no bone graft at 3-24 months post-operatively (p < 0.05). Within the bone graft group, the VBG group fared superior at 6 and 12 months post-operatively compared to non-VBG (p < 0.05), as well as a lower rate of radiological junctional resorption (p = 0.04). CONCLUSIONS: We recommend bone grafting for its merits of less implant loosening. We propose the VBG technique to combat early aseptic loosening in megaprosthesis replacement as there was a higher radiological score compared to non-VBG.

What Is the 10-year Survivorship of Cemented Distal Femoral Endoprostheses for Tumor Reconstructions and What Radiographic Features Are Associated with Survival?

BACKGROUND: Aseptic loosening is one of the most common causes of revision of distal femoral endoprostheses and is considered a mid- to long-term complication. There are not many reports of 10-year survivorship free from aseptic loosening and all-cause survivorship in cemented stems. To our knowledge, there are no reports on radiographic features that are associated with aseptic loosening of these implants. QUESTIONS/PURPOSES: (1) What is the 5- and 10-year survivorship free from aseptic loosening in patients undergoing reconstruction with a cemented distal femoral endoprosthesis after a tumor resection? (2) What is the all-cause 5- and 10-year survivorship at in these patients? (3) What radiographic features are associated with aseptic loosening at long-term follow-up? METHODS: We performed a multicenter retrospective study reviewing aseptic loosening in cemented prostheses to determine radiographic features associated with long-term implant survivorship. Patients who underwent a cemented distal femoral reconstruction with a modular endoprosthesis after resection of a musculoskeletal tumor between 1997 and 2017 were reviewed. A total of 246 patients were identified from five institutions and met initial inclusion criteria. Of those, 21% (51) were lost to follow-up before 2 years, leaving 195 patients available for us to evaluate and analyze the survivorship and radiologic features associated with long-term implant survival. The mean (range) follow-up was 78 months (22 to 257). At the time of this analysis, 69% (135 of 195) of the patients were alive. Osteosarcoma was the most common diagnosis in 43% of patients (83 of 195), followed by metastatic carcinoma 13% (25 of 195). Fifty-six percent (110 of 195) of patients received chemotherapy; 15% (30 of 195) had radiation therapy. Aseptic loosening was diagnosed radiographically and was defined as a circumferential radiolucent line on all views, or subsidence around the stem in the absence of infection. We present 5- and 10-year Kaplan-Meier survivorship free from aseptic loosening, 5- and 10-year all-cause survivorship, and a qualitative assessment of radiographic features potentially associated with aseptic loosening (including the junctional radiolucent area, and cortical expansion remodeling). The junctional radiolucent area was defined as a radiolucent area of the bone starting at the bone-endoprosthesis junction to the tip of the femoral stem, and cortical expansion remodeling was defined as an increased cortical thickness at the stem tip. Although we wished to statistically analyze radiographic factors potentially associated with aseptic loosening, we did not have enough clinical material to do so (only nine patients developed loosening). Instead, we will report a few preliminary qualitative observations, which necessarily are preliminary, and which will need to be confirmed or refuted by future studies. We urge caution in interpreting these findings because of the very small numbers involved. RESULTS: Kaplan-Meier survivorship free from aseptic loosening of the femoral component at 5 and 10 years were 95% (95% CI 89 to 98) and 93% (95% CI 86 to 97), respectively. Kaplan-Meier survivorship free from revision for any cause at 5 and 10 years were 74% (95% CI 65 to 79) and 64% (95% CI 49 to 70), respectively. Although the numbers were too small to analyze statistically, all patients with aseptic loosening had a junctional radiolucent area more than 20% of the total length of the stem without cortical expansion remodeling at the stem tip. No aseptic loosening was observed if there was cortical ex remodeling, a junctional radiolucent area less than 20%, or curved stems that were 13 mm or greater in diameter. The numbers of patients with aseptic loosening in this series were too small to analyze statistically. CONCLUSIONS: Cemented distal femoral endoprostheses have a relatively low rate of aseptic loosening and acceptable projected first-decade survivorship. The presence of a radiolucent area more than 20% without cortical expansion remodeling at the stem tip may lead to aseptic loosening in patients with these implants. Close radiographic surveillance and revision surgery may be considered for progressive lucencies and clinical symptoms of pain. If revision is contemplated, we recommend using larger diameter curved cemented stems. These are preliminary and provisional observations based on a low number of patients with aseptic loosening; future studies with greater numbers of patients are needed to validate or refute these findings. LEVEL OF EVIDENCE: Level III, therapeutic study.

Antibiotic-laden cement wrap: A simple but effective way of treating patients with megaprosthesis infection.

Infection is one of the commonest causes for megaprosthesis failure. The current treatment includes antibiotics but no surgery, debridement, prosthesis removal and joint fusion, prosthesis revision or amputation. Success in controlling infection may be less than 50% in implant revision. The overall risk of amputation is more than 20%. We believe that repeated debridement with antibiotic-laden cement wrap (ALCW) may be a reliable alternative for managing the megaprosthesis infection. The purposes of this article are to identify whether ALCW is an effective way of eradicating the megaprosthesis infection, the associated complications and the functional outcome after management by ALCW. METHODS: This was a retrospective study of patients with megaprosthesis infection. From January 2014 to June 2016, there were five patients with tumour megaprosthesis infection who had undergone the ALCW procedure. Ages ranged from 17 to 59 years of age. Male to female ratio was 4:1. The patients studied had humeral (1), proximal femoral (1), distal femoral (1) and proximal tibial (2) prostheses. All patients had follow-ups more than 1 year (21-52 months) after treatment. RESULTS: All patients recovered from their implant infection and the implants were retained in all patients. There was no sign of infection in the most recent follow-up. One patient died of osteosarcoma recurrence. One patient had a large block of cement causing plastic insert dislodgement in the shoulder joint 1 year after surgery. Another patient with a dislocated hip cup had revision carried out in the final debridement. The most recent Musculoskeletal Tumor society (MSTS) scores ranged from 21 to 30. All patients were satisfied with their treatment. CONCLUSIONS: In this preliminary report of a small number of patients, ALCW has achieved 100% infection control. ALCW may be an easy and effective alternative for managing the megasprosthesis infection. The complications associated can be avoidable. The functional outcome is excellent.

Is It Possible and Safe to Perform Acetabular-preserving Resections for Malignant Neoplasms of the Periacetabular Region?

BACKGROUND: Primary malignant tumors located near the acetabulum are usually managed by resection of the tumor with wide margins that include the acetabulum. These resections are deemed P2 resections by the Enneking and Dunham classification. There are various methods to perform the subsequent hip reconstruction. Unfortunately, there is no consensus as to the best management. In general, patients undergoing resection at this level will have substantial levels of pain and disability as measured by the Musculoskeletal Tumor Society (MSTS) scoring system. We believe there is a subset of patients whose tumors in this location can be resected while preserving all or most of the weightbearing acetabulum using navigation and careful surgical planning. QUESTIONS/PURPOSES: (1) What complications were associated with this resection; (2) what oncological outcomes (histological margins and local recurrence) were achieved; and (3) what is the function achieved by these patients? METHODS: This was a retrospective study of patients with periacetabular primary malignancy. From 2008 to 2014, we treated 12 patients who had periacetabular primary malignant tumors and in five, we performed resection with the weightbearing portion spared. During this period, our general indications to perform a resection that spared the acetabulum were the tumor with its resection margin not involving the weightbearing portion of the acetabulum. However, we did not perform this procedure in patients who had more cranial lesion involving the weightbearing portion or whose hip stability might be in question after the tumor excision. Three patients were women and the other two were men. Four were chondrosarcomas, whereas the other one was synovial sarcoma. Ages ranged from 46 to 60 years (average, 53 years). Minimum followup was 14 months (median, 37 months; range, 14-88 months); no patients were lost to followup before a 1-year minimum was achieved, and all patients have been seen within the last 9 months. RESULTS: There were no intraoperative or early postoperative complications. None of the five patients had a positive margin by histological assessment. No local recurrences were detected. The median functional score by MSTS was 28 out of 30 (range, 27-30). CONCLUSIONS: The roof of the acetabulum is the weightbearing portion of the acetabulum. It also maintains the stability of the hip. With precise preoperative planning of the resection and accurate execution of the procedure, the hip-sparing approach through partial acetabular resection can be performed in selected patients with malignant periacetabular neoplasms. Navigation makes it possible to minimize the amount of bone resection. In this preliminary report of a small number of patients, we had adequate short-term local tumor control. We believe the function is good, but we do not have a comparison group of patients to document improved function. LEVEL OF EVIDENCE: Level IV, therapeutic study.

IRX1 hypomethylation promotes osteosarcoma metastasis via induction of CXCL14/NF-κB signaling.

Osteosarcoma is a common malignant bone tumor with a propensity to metastasize to the lungs. Epigenetic abnormalities have been demonstrated to underlie osteosarcoma development; however, the epigenetic mechanisms that are involved in metastasis are not yet clear. Here, we analyzed 2 syngeneic primary human osteosarcoma cell lines that exhibit disparate metastatic potential for differences in epigenetic modifications and expression. Using methylated DNA immunoprecipitation (MeDIP) and microarray expression analysis to screen for metastasis-associated genes, we identified Iroquois homeobox 1 (IRX1). In both human osteosarcoma cell lines and clinical osteosarcoma tissues, IRX1 overexpression was strongly associated with hypomethylation of its own promoter. Furthermore, experimental modulation of IRX1 in osteosarcoma cell lines profoundly altered metastatic activity, including migration, invasion, and resistance to anoikis in vitro, and influenced lung metastasis in murine models. These prometastatic effects of IRX1 were mediated by upregulation of CXCL14/NF-κB signaling. In serum from osteosarcoma patients, the presence of IRX1 hypomethylation in circulating tumor DNA reduced lung metastasis-free survival. Together, these results identify IRX1 as a prometastatic gene, implicate IRX1 hypomethylation as a potential molecular marker for lung metastasis, and suggest that epigenetic reversion of IRX1 activation may be beneficial for controlling osteosarcoma metastasis.

Computer-assisted navigation in bone tumor surgery: seamless workflow model and evolution of technique.

BACKGROUND: Computer-assisted navigation was recently introduced to aid the resection of musculoskeletal tumors. However, it has not always been possible to directly navigate the osteotomy with real-time manipulation of available surgical tools. Registration techniques vary, although most existing systems use some form of surface matching. QUESTIONS/PURPOSES: We developed and evaluated a workflow model of computer-assisted bone tumor surgery and evaluated (1) the applicability of currently available software to different bones; (2) the accuracy of the navigated excision; and (3) the accuracy of a new registration technique of fluoro-CT matching. METHODS: Our workflow involved detailed preoperative planning with CT-MRI image fusion, three-dimensional mapping of the tumor, and planning of the resection plane. Using the workflow model, we reviewed 15 navigation procedures in 12 patients, including four with joint-saving resections and three with custom implant reconstructions. Intraoperatively, registration was performed with either paired points and surface matching (Group 1, n = 10) or a new technique of fluoro-CT image matching (Group 2, n = 5). All osteotomies were performed under direct computer navigation. Postoperatively, each case was evaluated for histologic margin and gross measurement of the achieved surgical margin. RESULTS: The margins were free from tumor in all resected specimens. In the Group 1 procedures, the correlation between preoperative planned margins and actual achieved margins was 0.631, whereas in Group 2 procedures (fluoro-CT matching), the correlation was 0.985. CONCLUSIONS: Our findings suggest computer-assisted navigation is accurate and useful for bone tumor surgery. The new registration technique using fluoro-CT matching may allow more accurate resection of margins.