Koji Nozaka

Dr. Koji Nozaka

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Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 May 2014 in BMC Research Notes
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Journal Article
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KNKoji Nozaka
Koji Nozaka
YSYoichi Shimada
Yoichi Shimada
NMNaohisa Miyakoshi
Naohisa Miyakoshi
SYShin Yamada
Shin Yamada
MHMichio Hongo
Michio Hongo
HKHiroaki Kijima
Hiroaki Kijima
Low-intensity pulsed ultrasound is a pain-free therapy performed daily at home by the patient and has been shown to promote fracture healing. Teriparatide is a parathyroid hormone preparation that activates osteoblastic bone formation and is also reported to be effective in promoting bony union. We report the case of a 56-year-old Japanese male with a femoral shaft fracture who underwent intramedullary osteosynthesis nailing initially. He had no radiologic or clinical sign of healing 3 months later and low-intensity pulsed ultrasound was initiated at that time. He was reassessed in another 3 months, with evidence of mild bone consolidation but the fracture gap persisted. Subsequent treatment with human parathyroid hormone was initiated in combination with low-intensity pulsed ultrasound. Full fracture healing was present 6 months after beginning the combination low-intensity pulsed ultrasound and teriparatide. It is hypothesized that the potential additive effects of low-intensity pulsed ultrasound and teriparatide therapy ultimately triggered sufficient bone formation to support osseous union. The case reported herein is a femoral shaft atrophic nonunion in which traditional interventions failed. Successful fracture healing was finally achieved with low-intensity pulsed ultrasound and teriparatide therapy. This is the first reported case of diaphyseal nonunion with deterioration of bone quality in long bones resolved with teriparatide and low-intensity pulsed ultrasound.

1 March 2021 in Journal of Orthopaedic Science
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Journal Article
Open access
KNKoji Nozaka
Koji Nozaka
NMNaohisa Miyakoshi
Naohisa Miyakoshi
HSHidetomo Saito
Hidetomo Saito
HKHiroaki Kijima
Hiroaki Kijima
SCShuichi Chida
Shuichi Chida
YSYoichi Shimada
Yoichi Shimada
Pilon fractures are associated with soft tissue complications such as skin necrosis, and deep infections have been reported very often. This study retrospectively compared the treatment effects of Ilizarov external fixation and of internal fixation methods in elderly patients with pilon fractures. A total of 37 patients >60 years old with pilon fractures (AO classification type 43) were investigated. Patients were treated either with internal fixation (n = 15) or Ilizarov external fixation (n = 22). The patients' mean age was 74.2 (range, 60-78) years in the internal fixation group and 76.1 (range, 60-82) years in the Ilizarov external fixation group. Many patients in the internal fixation group received toe-touch to 1/3 partial weight-bearing at 2-4 weeks postoperatively and full weight-bearing by 6-8 weeks postoperatively. Many patients in the Ilizarov external fixation group received partial weight-bearing (as tolerated) 1 day postoperatively, 1/2 partial weight-bearing at 2 weeks postoperatively, and full weight-bearing at 4 weeks postoperatively. The mean duration of hospitalization was 79.1 ± 30.1 days for the internal fixation group and 29.1 ± 18.8 days for the Ilizarov external fixation group (p < 0.05). Bone mineral density (T-score) was 2.6 ± 0.7 for the internal fixation group and 3.6 ± 1.2 for the Ilizarov external fixation group (p < 0.05). The incidence of skin disorders that required additional surgical treatment was 33.3% (5/15 patients) in the internal fixation group and 0% (0/22 patients) in the Ilizarov external fixation group (p < 0.05). In elderly patients with periarticular fractures of the ankle, those who underwent Ilizarov external fixation had a shorter duration of hospitalization and fewer complications than those who underwent internal fixation.

20 November 2021 in Osteoporosis and Sarcopenia
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Open access
HSHikaru Saito
Hikaru Saito
NMNaohisa Miyakoshi
Naohisa Miyakoshi
YKYuji Kasukawa
Yuji Kasukawa
KNKoji Nozaka
Koji Nozaka
HTHiroyuki Tsuchie
Hiroyuki Tsuchie
YSYoichi Shimada
Yoichi Shimada
The purpose of this study is to investigate the stage of chronic kidney disease (CKD) in adenine-induced CKD model rats by serum analyses, and to examine bone mineral density (BMD), bone strength, and microstructure of trabecular and cortical bone in these rats. Eight-week-old, male Wistar rats (n = 42) were divided into 2 groups: those fed a 0.75% adenine diet for 4 weeks until 12 weeks of age to generate CKD model rats (CKD group); and sham rats. The CKD and sham groups were sacrificed at 12, 16, and 20 weeks of age (n = 7 in each group and at 12, 16, and 20 weeks), and various parameters were evaluated, including body weight, renal wet weight, muscle wet weight, renal histology, biochemical tests, BMD, biomechanical testing, and micro-computed tomography (CT). The parameters were compared between the 2 groups at the various time points. In the CKD model rats, at 20 weeks of age, serum creatinine, phosphorus, and intact-PTH levels were elevated, and serum calcium levels were normal, indicating that the CKD was stage IV and associated with secondary hyperparathyroidism. Decreased BMDs of the whole body and the femur were observed as bone changes, and micro-CT analysis showed deterioration of bone microstructure of the cortical bone that resulted in decreased bone strength in the cortical and trabecular bone. These CKD model rats showed stage IV CKD and appear appropriate for evaluating the effects of several treatments for CKD-related osteoporosis and mineral bone disorder.

14 January 2020 in BMC Musculoskeletal Disorders
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Journal Article
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KNKoji Nozaka
Koji Nozaka
NMNaohisa Miyakoshi
Naohisa Miyakoshi
TKTakeshi Kashiwagura
Takeshi Kashiwagura
YKYuji Kasukawa
Yuji Kasukawa
HSHidetomo Saito
Hidetomo Saito
YSYoichi Shimada
Yoichi Shimada
Background: In highly active older individuals, end-stage ankle osteoarthritis has traditionally been treated using tibiotalar arthrodesis, which provides considerable pain relief. However, there is a loss of ankle joint movement and a risk of future arthrosis in the adjacent joints. Distraction arthroplasty is a simple method that allows joint cartilage repair; however, the results are currently mixed, with some reports showing improved pain scores and others showing no improvement. Distal tibial osteotomy (DTO) without fibular osteotomy is a type of joint preservation surgery that has garnered attention in recent years. However, to our knowledge, there are no reports on DTO with joint distraction using a circular external fixator. Therefore, the purpose of this study was to examine the effect of DTO with joint distraction using a circular external fixator for treating ankle osteoarthritis. Methods: A total of 21 patients with medial ankle arthritis were examined. Arthroscopic synovectomy and a microfracture procedure were performed, followed by angled osteotomy and correction of the distal tibia; the ankle joint was then stabilized after its condition improved. An external fixator was used in all patients, and joint distraction of approximately 5.8 mm was performed. All patients were allowed full weight-bearing walking immediately after surgery. Results: The anteroposterior and lateral mortise angle during weight-bearing, talar tilt angle, and anterior translation of the talus on ankle stress radiography were improved significantly (P < 0.05). Signal changes on magnetic resonance imaging also improved in all patients. Visual analog scale and American Orthopedic Foot & Ankle Society scores improved significantly (P < 0.05), and no severe complications were observed. Conclusion: DTO with joint distraction may be useful as a joint-preserving surgery for medial ankle osteoarthritis in older patients with high levels of physical activity. Level of evidence: Level IV, retrospective case series.

21 May 2020 in BMC Musculoskeletal Disorders
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Journal Article
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KNKoji Nozaka
Koji Nozaka
NMNaohisa Miyakoshi
Naohisa Miyakoshi
MHMichio Hongo
Michio Hongo
YKYuji Kasukawa
Yuji Kasukawa
HSHidetomo Saito
Hidetomo Saito
YSYoichi Shimada
Yoichi Shimada
Background: The incidence of periprosthetic fractures after total joint arthroplasty (TJA) is rising due to an increasing number of TJAs performed annually and the growing elderly population. In many elderly patients with periprosthetic fractures, the bone strength is lowered due to the deterioration of bone quality and a decrease in bone quantity; rigid fixation of the fracture is difficult. It is a challenging operation for orthopedic surgeons. The usefulness of circular external fixation for periprosthetic fractures has been reported in several case studies. The aim of this study was to investigate the rate of union and complications associated with circular external fixation in periprosthetic fractures around the knee.Methods: We included 19 patients with periprosthetic femur and tibial fractures who underwent osteosynthesis using a circular external fixator and had at least 2 years of follow-up. All patients had comorbidities and high risks associated with anesthesia. Tourniquets were not used in any of the patients. There were no cases in which the skin incision was placed, and the closed reduction technique was used in all cases.Results: A 100% union rate was achieved with no serious complications. All fractures healed after a mean time of 14.3 ± 5.2 weeks (range, 8–38 weeks). The walking ability was the same level as before the injury in 13 cases.Discussion: There are many comorbidities associated with periprosthetic fractures in elderly patients. Double-plate or revision surgery were largely invasive and had high risks associated with anesthesia. Circular external fixation is a feasible and effective treatment option because it provides stable fixation, prompt postoperative mobilization, and has no major complications, especially in elderly patients who are treated for periprosthetic fractures.Conclusion: Circular external fixation is a safe and reliable method for periprosthetic fractures around the knee in elderly patients.Level of evidence: Level IV, retrospective case series.

8 July 2014 in BMC Musculoskeletal Disorders
Verified
Journal Article
Open access
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KNKoji Nozaka
Koji Nozaka
YSYoichi Shimada
Yoichi Shimada
NMNaohisa Miyakoshi
Naohisa Miyakoshi
SYShin Yamada
Shin Yamada
YKYuji Kasukawa
Yuji Kasukawa
ANAtsuko Noguchi
Atsuko Noguchi
Alagille syndrome is a multisystem disorder, which is characterized by hypoplasia of the intrahepatic bile ducts, malformations of the cardiovascular system, eyes, and vertebral column, and abnormal facies. Several of the characteristics of Alagille syndrome may result in an especially high risk of fracture. The majority of patients suffer from chronic cholestasis, which can have a variety of adverse effects on bone metabolism. In Alagille syndrome, fractures primarily occur in the lower limb long bones in the absence of significant trauma. A 9-year-old Japanese girl with Alagille syndrome was admitted to our institution with marked hyperbilirubinemia and a pathological fracture of the femur. She had been diagnosed with biliary atresia at the age of 1 month and treated with surgical bile duct reconstruction, vitamins D and K, and ursodeoxycholic acid. However, her liver dysfunction and hyperbilirubinemia worsened. The pathological fracture of the femur was treated with low-intensity pulsed ultrasound stimulation (LIPUS) and an Ilizarov ring fixator. Seventy-four days after surgery, the patient had anatomically and functionally recovered. There was no leg-length discrepancy and no angular malalignment of the lower extremities as measured clinically and radiographically. The range of motion of the hip, knee, and ankle of the patient’s operative leg matched the range of motion in the nonoperative leg. To the best of our knowledge, there are no reports on use of the Ilizarov frame and LIPUS in diaphyseal femoral fractures in Alagille syndrome. This case report provides evidence that this procedure is successful for managing such diaphyseal fractures in Alagille syndrome.