Silver-Coated Megaprosthesis of the Proximal Tibia in Patients With Sarcoma

Background

Proximal tibia arthroplasty is associated with high rates of infection. This study is the largest one that has compared the infection rates with titanium vs silver-coated megaprostheses in patients treated for sarcomas.

The Modular Universal Tumour And Revision System (MUTARS®) in endoprosthetic revision surgery

The aim of this study was to present the clinical and functional results of revision surgery after failed hip endoprostheses using the Modular Universal Tumour And Revision System (MUTARS®). Functional results of the hip endoprostheses were recorded by applying the Harris hip score. The extent of the presurgical radiological bone defect was measured according to the classification system of the German orthopaedic association (DGOOC). Indications for revision surgery on 45 patients (21 female, 24 male) were aseptic loosening (19 patients), infection (16 patients), or periprosthetic fracture (Vancouver classification B2, B3 and C, in nine patients). Revision surgery was performed after 8.6 years on average (min. 0.6; max. 14.25 years). Large defects of the proximal femur (80% medial or lateral diaphysis; 20% meta-diaphysis according to DGOOC classification) were adequately reconstructed. The average follow-up was 38.6 months. Complications occurred in eight patients: one luxation, two aseptic loosenings, and five reinfections were diagnosed. The Harris hip score (presurgical 30; postsurgical 78) showed significant improvement after revision surgery. Regarding the extent of the patients’ bone defects, good functional results were achieved. The comparatively low number of luxations and loosenings is due to the high modularity of the prosthesis with arbitrary antetorsion in the hip joint. However, high reinfection rates in mega-implants still constitute a problem and should be the subject of further studies.     

Die juvenile Knochenzyste

Background

A unicameral bone cyst (UBC) may be caused by an intraosseous venous obstruction with the accumulation of interstitial fluid. Therefore, continuous decompression of the fluid using cannulated screws would represent a causal therapeutic approach.

Materials and methods

The clinical and radiographic follow-up of 17 patients with UBCs treated by curettage and mechanical decompression using cannulated screws was evaluated retrospectively.

Results

Radiographic examination revealed the following results: complete healing of the lesion (n=2), persistent defect after healing (n=6), persistent lesion (n=6), and recurrent cyst after temporary remodeling (n=3). No pathologic fracture was subsequently observed in the group of lesions that had a persistent defect after healing. A persistent lesion occurred in the proximal femur in 75% of the cases and in the proximal humerus in 50% of the cases.

Conclusion

Continuous decompression using cannulated screws can be applied in UBCs of the proximal humerus in patients with recurrent fractures and subjective complaints. However, treatment failures are common and comparable to other therapeutic approaches. Therefore, conservative treatment must be discussed critically. Healing with residual defect must be regarded as a good treatment result, and additional operative procedures with the objective of radiographic cosmetics should not be done. Because of poor results and long-term disability related to weight bearing, treatment of UBCs with cannulated screws cannot be recommended in lesions located in the proximal femur. In these cases, immediate surgical stabilization is the appropriate procedure.     

The ganglioside antigen G(D2) is surface-expressed in Ewing sarcoma and allows for MHC-independent immune targeting

Background:

Novel treatment strategies are needed to cure disseminated Ewing sarcoma. Primitive neuroectodermal features and a mesenchymal stem cell origin are both compatible with aberrant expression of the ganglioside antigen G_D2 and led us to explore G_D2 immune targeting in this cancer.

Methods:

We investigated G_D2 expression in Ewing sarcoma by immunofluorescence staining. We then assessed the antitumour activity of T cells expressing a chimeric antigen receptor specific for G_D2 against Ewing sarcoma in vitro and in vivo.

Results:

Surface G_D2 was detected in 10 out of 10 Ewing sarcoma cell lines and 3 out of 3 primary cell cultures. Moreover, diagnostic biopsies from 12 of 14 patients had uniform G_D2 expression. T cells specifically modified to express the G_D2-specific chimeric receptor 14. G2a-28ζ efficiently interacted with Ewing sarcoma cells, resulting in antigen-specific secretion of cytokines. Moreover, chimeric receptor gene-modified T cells from healthy donors and from a patient exerted potent, G_D2-specific cytolytic responses to allogeneic and autologous Ewing sarcoma, including tumour cells grown as multicellular, anchorage-independent spheres. G_D2-specific T cells further had activity against Ewing sarcoma xenografts.

Conclusion:

G_D2 surface expression is a characteristic of Ewing sarcomas and provides a suitable target antigen for immunotherapeutic strategies to eradicate micrometastatic cells and prevent relapse in high-risk disease.     

Cytotoxic effect of clodronate and zoledronate on the chondrosarcoma cell lines HTB-94 and CAL-78

The wide surgical tumour resection is the only effective treatment in chondrosarcoma. However, a major problem remains the high rate of local recurrences and metastases due to the lack of adjuvant therapies. In this study the cytotoxic effect of the bisphosphonate clodronate (0.1–1000 μM) and zoledronate (0.1–1000 μM) in different concentrations on two chondrosarcoma cell lines (HTB-94 and CAL-78) has been investigated. After an incubation period of 48, 72 and 96 hours the chondrosarcoma cell viability was measured as the MTT-proliferation rate. In concentrations of >1 μm zoledronate the cell activity was reduced by up to 95% for the CAL-78 cells. Further, zoledronate has been more effective in lower concentrations than clodronate in the reduction of cell viability for both cell lines. However, clodronate showed significant cytotoxic effects in high concentrations and after longer incubation periods. Further research is necessary, but in the light of these results bisphosphonates may also play a role in the treatment of chondrosarcomas.     

Knieendoprothesenimplantation bei übersehenem Osteosarkom

A 72-year-old woman presented with pain, swelling, and decreased range of motion of the left knee joint after total knee arthroplasty in 2005. We performed standard x-rays, which were highly suspicious for an osteosarcoma of the distal femur; this was proven by open biopsy. Retrospectively, the x-rays taken before implantation of the prosthesis showed suspicious findings. Because the femur was tumor-contaminated, with the intramedullary adjustment far-reaching proximally, a limb salvage procedure was no longer possible. To improve function, we decided to perform a stump-lengthening procedure using a special implant. With regard to the dismal consequences, we recommend that every suspicious finding before an elective surgical procedure be examined with further diagnostics and, if necessary, histological confirmation.