Elastic salmon collagen (SC) vascular grafts were prepared by incubating a mixture of acidic SC solution and a fibrillogenesis-inducing buffer containing a crosslinking agent [water-soluble carbodiimide (WSC)] in a tubular mold at 4 degrees C for 24 h and then at 60 degrees C for 5 min. Subsequently, re-crosslinking in ethanol solution containing WSC was performed. The dimension of the SC grafts was easily controlled by changing the size of the mold used. The compliance (stiffness parameter: beta) and burst strength of the SC grafts (internal diameter, 2 mm; length, 20 mm; and wall thickness, 0.75 mm) that were prepared for implantation were 18.2 and 1434 mmHg, respectively; both these values were comparable with those of native vessels. Upon placement in rat subcutaneous pouches, the SC grafts were gradually biodegraded with little inflammatory reaction. The SC grafts were preliminarily implanted in rat abdominal aortas by using specially designed vascular connecting system. This system was used because the graft exhibited easy tearing and thus inadequate suturability. There was neither aneurysm formation nor graft rupture, but mild thrombus formation was seen within the 4-week observation period. These grafts may be ideal for use in regenerative medicine because we believe that SC would be completely replaced with native vascular tissues after implantation, although further improvement in the mechanical properties of the graft is needed for anastomosis.

Rationale:Three-dimensional (3D) printed templates can be designed to match an individual's anatomy, allowing surgeons to refine preoperative planning. In addition, the use of computer navigation (NAV) is gaining popularity to improve surgical accuracy in the resection of pelvic tumors. However, its use in combination with 3D printing to assist complex pelvic tumor resection has not been reported.Patient concerns:A 36-year-old man presented with left-sided pelvic pain and a fast-growing mass. He also complained of a 3-month history of radiating pain and numbness in the lower left extremity.Diagnoses:A biopsy revealed an osteochondroma with malignant potential. This osteochondroma arises from the ilium and involves the sacrum and lower lumbar vertebrae.Interventions:Here, we describe a novel combined application of 3D printing and intraoperative NAV systems to guide hemipelvectomy for en-bloc resection of the osteochondroma. The 3D printed template is analyzed during surgical planning and guides the initial intraoperative bone work to improve surgical accuracy and efficiency, while a computer NAV system provides real-time imaging during the tumor removal to achieve adequate resection margins and minimize the likelihood of injury to adjacent critical structures.Outcomes:The tumor mass and the invaded spinal structures were removed en bloc.Lessons:The combined application of 3D printing and computer NAV may be useful for tumor targeting and safe osteotomies in pelvic tumor surgery.

We newly developed self-expandable covered stents by combining two of our original technologies. Of these, the first is the dip-coating covering method that was developed previously for balloon-expandable stents; the other is the newly developed self-expandable Nitinol stents, namely, Sendai stents. The three types of covered stents with the expansion diameter of 4.5, 5.0, or 6.0 mm thus obtained had a laser-processed microporous elastomeric cover film (pore diameter: 100 microm, interpore distance: 250 microm). Although the film was extremely thin (approximately 15 microm), the film could be expanded without causing any damage, the strut was completely embedded within the film, and the luminal surface of the film was smooth and flat. Mechanical properties such as ideal flexibility to follow the shapes of arteries were almost retained even after covering. As appropriate drugs, the blood-contacting inner and tissue-contacting outer surfaces of the film were differentially coated with argatroban for antithrombogenicity or FK506 for anti-inflammation, respectively. The preliminary in vivo study indicated that the covered stents mounted in the delivery catheter were navigated and placed to appropriate position in the arteries, and permissible neointimal thickening after 1-month implantation was observed similarly in noncovered stents.

Malignant rhabdoid tumor (MRT) is a highly malignant and aggressive tumor associated with the kidney that is mainly seen in children under 5 years old, resulting in a rapid fatal outcome. MRT invasion of the cervical vertebra is an extremely rare form of this malignancy. This study presents a case of MRT involving the C4 vertebra and its appendix. A 13-year-old girl was found to have vague neck pain and a mass in the left neck area of the mid-cervical spine. Percutaneous needle biopsy was performed and the histological and immunohistochemical analysis pointed towards a rhabdoid tumor. Chemotherapy and radiotherapy were performed, but the tumor mass progressively enlarged. Tumorectomy was conducted followed by another 6 courses of chemotherapy and ¹²⁵I radioactive seed implantation. Unfortunately, the C4 vertebra and its appendix were found to be abnormal 3 months after the end of therapy. The patient received an additional tumorectomy, internal fixation with C4 reconstruction by a combined anterior and posterior approach, and 6 courses of consolidation chemotherapy. She is still alive 40 months since the initial diagnosis and remains asymptomatic 31 months after the surgery.