Treatment of bone cysts by percutaneous injection of demineralized bone matrix mixed with bone marrow.

Bone cysts whether aneurysmal or simple, are known for their tendency to recur. To replace the classical aggressive surgeries, minimally invasive techniques were developed giving differing results based on variable radiographic criteria. No unique percutaneous treatment has proven effective on both types of cysts. The purpose of this study was to evaluate with volumetric MRI calculations the benefit of percutaneous injection of demineralized bone matrix mixed with autogenous bone marrow on both types of cysts. Twenty-seven cysts; 6 aggressive aneurysmal bone cysts (ABCs) and 21 active simple bone cysts (SBCs) were treated with our percutaneous treatment in this case series. Regular MRIs were performed to calculate their volumetric evolution starting before treatment and with a minimal two-year follow-up. A cyst was considered healed when its final residual volume shrank to less than 50%. To allow statistical comparison between both types of cysts, 13 previously reported ABCs treated with the same protocol in our institution were joined to the 6 present ABCs. Four ABCs healed with a single injection while the 2 others recurred. Five SBCs healed with a single injection, 9 others after a second injection and 2 others after a third injection. Five SBCs were considered non-healed. The present healing rate in 67% of ABCs is consistent with the previous series as there was no significant difference (p=0.37). The better global healing rate for ABC (79%) was not statistically different from the SBC healing rate (76%) (p=0.83). The percutaneous injection of demineralized bone matrix mixed with bone marrow is an effective treatment for both types of cysts.

MRI-Based Assessment of Safe Margins in Tumor Surgery.

Introduction. In surgical oncology, histological analysis of excised tumor specimen is the conventional method to assess the safety of the resection margins. We tested the feasibility of using MRI to assess the resection margins of freshly explanted tumor specimens in rats. Materials and Methods. Fourteen specimen of sarcoma were resected in rats and analysed both with MRI and histologically. Slicing of the specimen was identical for the two methods and corresponding slices were paired. 498 margins were measured in length and classified using the UICC classification (R0, R1, and R2). Results. The mean difference between the 498 margins measured both with histology and MRI was 0.3 mm (SD 1.0 mm). The agreement interval of the two measurement methods was [-1.7 mm; 2.2 mm]. In terms of the UICC classification, a strict correlation was observed between MRI- and histology-based classifications (κ = 0.84, P < 0.05). Discussion. This experimental study showed the feasibility to use MRI images of excised tumor specimen to assess the resection margins with the same degree of accuracy as the conventional histopathological analysis. When completed, MRI acquisition of resected tumors may alert the surgeon in case of inadequate margin and help advantageously the histopathological analysis.

Surgical guides (patient-specific instruments) for pediatric tibial bone sarcoma resection and allograft reconstruction.

To achieve local control of malignant pediatric bone tumors and to provide satisfactory oncological results, adequate resection margins are mandatory. The local recurrence rate is directly related to inappropriate excision margins. The present study describes a method for decreasing the resection margin width and ensuring that the margins are adequate. This method was developed in the tibia, which is a common site for the most frequent primary bone sarcomas in children. Magnetic resonance imaging (MRI) and computerized tomography (CT) were used for preoperative planning to define the cutting planes for the tumors: each tumor was segmented on MRI, and the volume of the tumor was coregistered with CT. After preoperative planning, a surgical guide (patient-specific instrument) that was fitted to a unique position on the tibia was manufactured by rapid prototyping. A second instrument was manufactured to adjust the bone allograft to fit the resection gap accurately. Pathologic evaluation of the resected specimens showed tumor-free resection margins in all four cases. The technologies described in this paper may improve the surgical accuracy and patient safety in surgical oncology. In addition, these techniques may decrease operating time and allow for reconstruction with a well-matched allograft to obtain stable osteosynthesis.