Okayama University Medical School Acta Medica Okayama 0386-300X 71 4 2017 An Analysis of the Characteristics and Improved Use of Newly Developed CT-based Navigation System in Total Hip Arthroplasty 279 289 EN Yosuke Fujii Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kazuo Fujiwara Department of Intelligent Orthopaedic System Development, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tomonori Tetsunaga Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takamasa Miyake Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kazuki Yamada Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hirosuke Endo Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Nobuhiro Abe Department of Orthopaedic Surgery, Kawasaki Medical school Naohiko Sugita Department of Mechanical Engineering, School of Engineering, The University of Tokyo Mamoru Mitsuishi Department of Mechanical Engineering, School of Engineering, The University of Tokyo Takayuki Inoue TEIJIN NAKASHIMA MEDICAL CO., LTD Yoshio Nakashima TEIJIN NAKASHIMA MEDICAL CO., LTD Toshifumi Ozaki Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Original Article 10.18926/AMO/55304 We developed a surface matching-type computed tomography (CT)-based navigation system for total hip arthroplasty (the N-navi; TEIJIN NAKASHIMA MEDICAL, Okayama, Japan). In the registration step, surface matching was performed with digitizing points on the pelvic bone surface after coarse paired matching. In the present study, we made model bones from the CT data of patients whose acetabular shapes had various deformities. We measured the distances and angles after surface matching from the fiducial points and evaluated the ability to correct surface-matching registration on each pelvic form, using several areas and numbers of points. When the surface-matching points were taken on the superior area of the acetabulum, the correction was easy for the external direction, but it was difficult to correct for the anterior and proximal directions. The correction was difficult for external and proximal directions on the posterior area. Each area of surface-matching points has particular directions that are easily corrected and other directions that are difficult to correct. The shape of the pelvis also affected the correction ability. Our present findings suggest that checking the position after coarse paired matching and choosing the surface-matching area and points that are optimal to correct will improve the accuracy of total hip arthroplasty and reduce surgical times. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 71 1 2017 Verification of Implant Surface Modification by a Novel Processing Method 49 57 EN Yoshiki Okada Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Nobuhiro Abe Department of Orthopaedic Surgery and Sport Medicine, General Medical Center Kawasaki Medical School Noriyuki Hisamori Department of Science and Engineering, Sophia University Toshiaki Kaneeda Department of Mechanical System Engineering, Okayama University of Science Shigeaki Moriyama Department of Mechanical Engineering, Fukuoka University Hitoshi Ohmori Riken Ohmori Materials Fabrication Laboratory Masayoshi Mizutani Department of Mechanical Systems and Design, Graduate School of Engineering, Tohoku University Hiroyuki Yanai Department of Pathology, Okayama University Hospital Yoshio Nakashima Nakashima Medical Co., Ltd. Yusuke Yokoyama Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Toshifumi Ozaki Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Original Article 10.18926/AMO/54825 Metals have been used clinically as biomaterials, especially in the orthopaedic and dental fields. Metals used as implants wear at contact surfaces, producing metal particles and metal ions that may be harmful. Newly developed metal implants and methods of implant surface modification are currently under scrutiny. We evaluated the use of electrolytic in-process dressing (ELID) as a surface finishing method for metal implants. Metal implants processed using the ELID method (ELID group) or not processed (Non-ELID group) were inserted surgically into rabbit femurs. The rabbits were sacrificed postoperatively over a 24-week period. We assessed the concentrations of the cytokines, interleukin (IL)-1��, IL-6, and tumor necrosis factor-��, the resistance to implant pull-out, and histopathology at the implant site. There was no significant difference between the groups regarding the cytokine concentrations or implant pull-out resistance. Many particles indicating wear around the implant were noted in the Non-ELID group (n=10) but not the ELID group (n=13), while a fibrous membrane adhering to the every implant was noted in the ELID group. The formation of a fibrous membrane rather than metal particles in the ELID group may indicate improved biocompatibility, and it suggests that ELID may prevent corrosion in the areas of contact. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 69 6 2015 Contrast-enhanced Computed Tomography Screening Is Effective for Detecting Venous Thromboembolism not Prevented by Prophylaxis after Total Knee Arthroplasty 355 359 EN Yukimasa Okada Takayuki Furumatsu Shinichi Miyazawa Takaaki Tanaka Masataka Fujii Toshifumi Ozaki Nobuhiro Abe Original Article 10.18926/AMO/53910 Venous thromboembolism (VTE) is a potential complication occurring after total knee arthroplasty (TKA). We investigated the incidence of VTE after TKA using contrast-enhanced computed tomography (CT), and assessed the efficacy of VTE prophylaxis (fondaparinux and enoxaparin). At our hospital, 189 patients (225 knees) underwent TKA between April 2007 and October 2011. The 225 knees were divided into a control group with no VTE prophylaxis (31 cases), a fondaparinux group (107 cases), and an enoxaparin group (87 cases). Contrast-enhanced CT screening for VTE was performed in all cases on day 5 or 6 after TKA. D-dimer levels were measured on day 5 after TKA, and were significantly lower in the fondaparinux (9.8�}3.8) and enoxaparin groups (9.4�}4.9) than in the control group (15.6�}9.8) (p��0.001). However, no statistically significant difference in the incidence of VTE was observed among the groups (control, 61.3%;fondaparinux, 49.5%;enoxaparin, 50.6%). Prophylaxis was not effective for the prevention of VTE as detected by contrast-enhanced CT after TKA. CT should be performed after TKA, even when VTE prophylaxis is used. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 67 6 2013 A New Navigation System for Minimally Invasive Total Knee Arthroplasty 351 358 EN Yusuke Yokoyama Nobuhiro Abe Kazuo Fujiwara Masahiko Suzuki Yoshikazu Nakajima Naohiko Sugita Mamoru Mitsuishi Yoshio Nakashima Toshifumi Ozaki Original Article 10.18926/AMO/52008 A computer-assisted navigation system to be used for total knee arthroplasties (TKAs) was reported to improve the accuracy of bone resection and result in precise implant placement, but the concomitant surgical invasion and time consumption are clinical problems. We developed a computed tomography (CT)-based navigation system (NNS) to be used for minimally invasive TKA. It requires only the reference points from a small limited area of the medial femoral condyle and proximal tibia through a skin incision to obtain optical images. Here we evaluated the usefulness and accuracy of the NNS in comparison with the commercially available BrainLAB image-free navigation system (BLS). In a clinical experiment, the registration times obtained with the NNS tended to be shorter than those obtained with the BLS, but not significantly so. The NNS group tended to be in the extended position in the sagittal plane of the distal femur within 3 degrees, and the BLS group showed rather flexed deviation in the sagittal plane of the anterior femur. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 67 1 2013 Histological Analysis of Failed Cartilage Repair after Marrow Stimulation for the Treatment of Large Cartilage Defect in Medial Compartmental Osteoarthritis of the Knee 65 74 EN Kenichiro Sakata Takayuki Furumatsu Nobuhiro Abe Shinichi Miyazawa Yoshimasa Sakoma Toshifumi Ozaki Case Report 10.18926/AMO/49259 Bone marrow-stimulating techniques such as microfracture and subchondral drilling are valuable treatments for full-thickness cartilage defects. However, marrow stimulation-derived reparative tissues are not histologically well-documented in human osteoarthritis. We retrospectively investigated cartilage repairs after marrow stimulation for the treatment of large cartilage defects in osteoarthritic knees. Tissues were obtained from patients who underwent total knee arthroplasty (TKA) after arthroscopic marrow stimulation in medial compartmental osteoarthritis. Clinical findings and cartilage repair were assessed. Sections of medial femoral condyles were histologically investigated by safranin O staining and anti-type II collagen antibody. Marrow stimulation decreased the knee pain in the short term. However, varus leg alignment gradually progressed, and TKA conversions were required. The grade of cartilage repair was not improved. Marrow stimulations resulted in insufficient cartilage regeneration on medial femoral condyles. Safranin O-stained proteoglycans and type II collagen were observed in the deep zone of marrow-stimulated holes. This study demonstrated that marrow stimulation resulted in failed cartilage repair for the treatment of large cartilage defects in osteoarthritic knees. Our results suggest that arthroscopic marrow stimulation might not improve clinical symptoms for the long term in patients suffering large osteoarthritic cartilage defects. No potential conflict of interest relevant to this article was reported.