Publications by authors named "Shunsuke Fujibayashi"

157 Publications

Salvage Oblique Lateral Interbody Fusion for Pseudarthrosis after Posterior/Transforaminal Lumbar Interbody Fusion: A Technical Note.

World Neurosurg 2021 Jun 12;152:107-112. Epub 2021 Jun 12.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Objective: This study aims to demonstrate the efficacy of salvage oblique lumbar interbody fusion (OLIF) surgery for pseudarthrosis after posterior/transforaminal lumbar interbody fusion (PLIF/TLIF).

Methods: The study group were patients with leg or back pain induced by pseudarthrosis after PLIF/TLIF. These patients underwent salvage OLIF surgeries in our institutions between July 2015 and Oct 2019. We retrospectively evaluated their clinical and radiographic outcomes.

Results: Seven consecutive patients (all male; mean age 68.4 ± 9.3 years, range 53-81 years) were included in this study. There was no intraoperative complications in all cases. Six of 7 patients achieved bone union (at average 33.4 months follow-up) and had a successful postoperative course. Only 1 patient failed to gain bony fusion and required additional revision surgery due to progression of sagittal and coronal malalignment at 18 months after salvage OLIF surgery.

Conclusions: The salvage OLIF approach was useful option for pseudarthrosis after PLIF/TLIF. It enabled us to build a rigid anterior support, allowed for extensive curettage of intervertebral scar tissue, and reduced the rate of the complications associated with dealing with posterior scar tissue.
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http://dx.doi.org/10.1016/j.wneu.2021.06.020DOI Listing
June 2021

Neurological improvement is associated with neck pain attenuation after surgery for cervical ossification of the posterior longitudinal ligament.

Sci Rep 2021 Jun 7;11(1):11910. Epub 2021 Jun 7.

Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan.

Although favourable surgical outcomes for myelopathy caused by cervical ossification of the posterior longitudinal ligament (OPLL) have been reported, factors significantly associated with post-operative neck pain attenuation still remain unclear. The primary aim of the present study was to determine factors significantly associated with post-operative neck pain attenuation in patients with cervical OPLL using a prospective multi-centre registry of surgically treated cervical OPLL. Significant postoperative neck pain reduction (50% reduction of neck pain) was achieved in 31.3% of patients. There was no significant difference in neck pain attenuation between surgical procedures. Statistical analyses with univariate analyses followed by stepwise logistic regression revealed neurological recovery as a factor having a significant positive association with post-operative neck pain attenuation (p = 0.04, odds ratio 5.68 (95% confidence interval: 1.27-22.2)). In conclusion, neurological recovery was an independent factor having a significant positive association with post-operative neck pain attenuation in patients with cervical myelopathy caused by OPLL who underwent cervical spine surgery.
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http://dx.doi.org/10.1038/s41598-021-91268-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8184776PMC
June 2021

Rigid reconstruction with periacetabular multiple screws after the resection of malignant pelvic tumours involving the sacroiliac joint.

Int Orthop 2021 07 4;45(7):1793-1802. Epub 2021 Jun 4.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, Japan.

Background: Reconstruction of the pelvic ring after the resection of pelvic tumours involving the sacroiliac joint is challenging. Although pedicle screw and rod system reconstructions are commonly performed, failure at the early stage has been reported. Surgical procedures Reconstruction involving two or more strong anchor screws (iliac, ischial, and pubis screws) into the residual pelvis, connecting with at least two rods with minimal bending to the residual lumbosacral vertebra and contralateral pelvis.

Methods: The above reconstruction was performed for six malignant bone and soft-tissue pelvic tumours requiring Enneking type I + IV resection. A double-barreled free non-vascularized fibular graft was used in all patients, except for one. Patients were followed up for a mean period of 51 months (range, 9 to 96 months), and peri-operative complications, implant failure within the follow-up period, and the clinical results of surgery were investigated.

Results: The mean age of four females and two males at the initial surgery was 37.2 years. One patient developed a deep wound infection. Two patients died due to metastasis of the tumor. All patients were able to walk on their own within 12 weeks of surgery. There was no implant failure, except in two patients with contralateral lumbosacral rod fracture three and four years after surgery, for which one patient required rod replacement.

Conclusions: The incidence of implant failure, particularly around the resection site, was low, which may be attributed to multiple periacetabular screws and rods with minimal bending. Our rigid reconstruction method enables the rapid resumption of walking.
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http://dx.doi.org/10.1007/s00264-021-05096-0DOI Listing
July 2021

Machine Learning Approach in Predicting Clinically Significant Improvements After Surgery in Patients with Cervical Ossification of the Posterior Longitudinal Ligament.

Spine (Phila Pa 1976) 2021 May 21. Epub 2021 May 21.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Japan Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo Ward, Tokyo 113-8519, Japan Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchishi, Saitama, 332-8558, Japan Department of Orthopedic Surgery, Kudanzaka Hospital, 1-6-12 Kudanminami, Chiyadaku, 102-0074, Japan Department of Orthopaedic Surgery, Wakayama Medical University Kihoku Hospital 210 Myoji, Katsuragi-cho, Itogun, Wakayama 649-7113, Japan Department of Orthopedic Surgery, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan Department of Orthopedic Surgery, Niigata University Medical and Dental General Hospital, 1-754 Asahimachidori, Chuo Ward, Niigata, Niigata 951-8520, Japan Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, 2- 1-1 Amakubo, Tsukuba, Ibaraki 305-8576, Japan Department of Orthopedics, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan Department of Orthopedic Surgery, School of Medicine, Keio University, Shinanomachi, Shinjuku Ward, Tokyo 160-8582, Japan Department of Orthopedic Surgery, Yamaguchi University School of Medicine 1144 Kogushi, Ube, Yamaguchi 755-8505, Japan Department of Orthopedic Surgery, Osaka Rosai Hospital, 1179-3 Nagasonecho, Sakaishi, Osaka, 591-8025, Japan Department of Orthopaedic Surgery, The University of Tokyo Hospital 3-28-6 Mejirodai, Bunkyo-ku, Tokyo 112-8688, Japan Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumaicho, Showa Ward, Nagoya, Aichi 466-0065, Japan Orthopedic Surgery, Reconstructive Surgery and Rehabilitation Medicine, Division of Advanced Medical Science, Hokkaido University, Graduate School of Medicine Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan Department of Orthopaedic Surgery, Shiga University of Medical Science, Tsukinowa- cho, Seta, Otsu, Shiga 520-2192, Japan Department of Orthopaedics and Rehabilitation Medicine, University of Fukui Faculty of Medical Sciences, 23-3 Shimoaizuki, Matsuoka, Fukui 910-1193, Japan Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan Department of Orthopedic Surgery, Imakiire General Hospital, 4-16 Shimotatsuocho, Kagoshima-shi, 892-8502, Japan Department of Orthopedic Surgery, Graduate School of Medicine, Osaka University 2-2 Yamadaoka, Suita-shi, Osaka 565-0871, Japan Department of Orthopaedic Surgery, Kurume University School of Medicine 67 Asahi-machi, Kurume-shi, Fukuoka 830-0011, Japan Department of Orthopedic Surgery, Hamamatsu University School of Medicine, 1- 20-1 Handayama, Hamamatsu, Shizuoka 431-3125, Japan Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa, 920-8641, Japan Department of Orthopedic Surgery, University of Yamanashi, 1110 Shimokato, Chuo Ward, Yamanashi 409-3898, Japan Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi 321-0293, Japan Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan Department of Orthopedic Surgery, Surgical Science, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryomachi, Aoba Ward, Sendai, Miyagi 980-8574, Japan Department of Orthopedic Surgery, Faculty of Medicine, University of Toyama, 2630 Sugitani, Toyama, Toyama 930-0194, Japan Japanese Multicenter Research Organization for Ossification of the Spinal Ligament.

Study Design: A retrospective analysis of prospectively collected data.

Objective: This study aimed to create a prognostic model for surgical outcomes in patients with cervical ossification of the posterior longitudinal ligament (OPLL) using machine learning (ML).

Summary Of Background Data: Determining surgical outcomes helps surgeons provide prognostic information to patients and manage their expectations. ML is a mathematical model that finds patterns from a large sample of data and makes predictions outperforming traditional statistical methods.

Methods: Out of 478 patients, 397 and 370 patients had complete follow-up information at 1 and 2 year respectively and were included in the analysis. A minimal clinically important difference (MCID) was defined as an acquired Japanese Orthopaedic Association (JOA) score of 2.5 points or more, after which a ML model that predicts whether MCID can be achieved 1 and 2 years after surgery was created. Patient background, clinical symptoms, and imaging findings were used as variables for analysis. The ML model was created using LightGBM, XGBoost, random forest, and logistic regression, after which the accuracy and area under the receiver operating characteristic curve (AUC) were calculated.

Results: The mean JOA score was 10.3 preoperatively, 13.4 at 1 year after surgery, and 13.5 at 2 years after surgery. XGBoost showed the highest AUC (0.72) and high accuracy (67.8) for predicting MCID at 1 year, while random forest had the highest AUC (0.75) and accuracy (69.6) for predicting MCID at 2 years. Among the included features, total preoperative JOA score, duration of symptoms, body weight, sensory function of the lower extremity sub-score of the JOA, and age were identified as having the most significance in most of ML models.

Conclusion: Constructing a prognostic ML model for surgical outcomes in patients with OPLL is feasible, suggesting the potential application of ML for predictive models of spinal surgery.Level of Evidence: 4.
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http://dx.doi.org/10.1097/BRS.0000000000004125DOI Listing
May 2021

Comparison of Surgical Outcomes After Open- and Double-Door Laminoplasties for Patients with Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Multicenter Study.

Spine (Phila Pa 1976) 2021 May 6. Epub 2021 May 6.

Department of Orthopaedic Surgery, School of Medicine, Keio University, Shinjuku Ward, Tokyo, Japan Department of Orthopedic Surgery, Tokyo Medical and Dental University, Bunkyo Ward, Tokyo, Japan Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, Kawaguchishi, Saitama, Japan Department of Orthopedic Surgery, Kudanzaka Hospital, Chiyodaku, Japan Department of Orthopaedic Surgery, Wakayama Medical University Kihoku Hospital, Katsuragi-cho, Itogun, Wakayama, Japan Department of Orthopedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan Department of Orthopedic Surgery, Niigata University Medicine and Dental General Hospital, Chuo Ward, Niigata, Niigata, Japan Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan Department of Orthopedics, Jichi Medical University, Shimotsuke, Tochigi, Japan Department of Orthopedic Surgery, Chiba University Graduate School of Medicine, Chuo Ward, Chiba, Japan Department of Orthopedic Surgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan Department of Orthopedic Surgery, Osaka Rosai Hospital, Sakaishi, Osaka, Japan Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine,, Showa Ward, Nagoya, Aichi, Japan Department of Orthopaedic Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan Department of Orthopaedic Surgery, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga, Japan Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences University of Fukui, Eiheiji-cho, Yoshida-gun, Fukui, Japan Department of Orthopedic Surgery, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan Department of Orthopedic Surgery, Imakiire General Hospital, Kagoshimashi, Japan Department of Orthopedic Surgery, Graduate School of Medicine, Osaka University, Suita-shi, Osaka, Japan Department of Orthopaedic Surgery, Kurume University School of Medicine, Kurume-shi, Fukuoka, Japan Department of Orthopedic Surgery, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan Department of Orthopedic Surgery, University of Yamanashi, Chuo Ward, Yamanashi, Japan Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, Mibu-machi, Shimotsuga-gun, Tochigi, Japan Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Shogoin, Sakyo-ku, Kyoto, Japan Department of Orthopedic Surgery, Surgical Science, Tokai University School of Medicine, Isehara, Kanagawa, Japan Department of Orthopaedic Surgery, Tohoku University School of Medicine, Aoba Ward, Sendai, Miyagi, Japan Department of Orthopedic Surgery, Faculty of Medicine, University of Toyama, Toyama, Toyama, Japan Japanese Multicenter Research Organization for Ossification of the Spinal Ligament.

Study Design: A prospective multicenter study.

Objective: To evaluate and compare the surgical outcomes after open-door (OD) and double-door (DD) laminoplasties in subjects with cervical ossification of the posterior longitudinal ligament (OPLL).

Summary Of Background Data: Although previous studies compared clinical results after OD and DD laminoplasties, they were performed at a single institution with a relatively small sample size targeting mixed pathologies, including cervical spondylotic myelopathy.

Methods: This study was performed by the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. A total of 478 patients with myelopathy caused by cervical OPLL from 28 institutions were prospectively registered from 2014 to 2017 and followed up for 2 years. Of these, 41 and 164 patients received OD and DD laminoplasties, respectively. Demographic information, medical history, and imaging findings were collected. Clinical outcomes were assessed using the cervical Japanese Orthopaedic Association (JOA), JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and visual analog scale (VAS) scores.

Results: Age, sex, symptom duration, and comorbidities were not significantly different between the groups. Segmental ossification was the most frequent in both groups. No significant differences in K-line type, canal occupying ratio, C2-C7 angles, and range of motion (ROM) were found. Both procedures reduced the cervical ROM postoperatively. A comparable frequency of perioperative complications was observed between the groups. The cervical JOA scores showed a similar improvement at 2 years postoperatively. The reduction in VAS score for neck pain was favorable in the OD group (P = 0.02), while other pain assessments did not show any significant differences between the groups. The functional outcomes assessed using the JOACMEQ presented equivalent effective rates.

Conclusion: The results demonstrated almost comparable surgical outcomes between OD and DD laminoplasties. Laminoplasty is a valuable technique as a therapeutic option for cervical OPLL.Level of Evidence: 5.
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http://dx.doi.org/10.1097/BRS.0000000000004094DOI Listing
May 2021

Bone Coverage around Hydroxyapatite/Poly(-Lactide) Composite Is Determined According to Depth from Cortical Bone Surface in Rabbits.

Materials (Basel) 2021 Mar 17;14(6). Epub 2021 Mar 17.

The Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 602-8570, Japan.

Composites of unsintered hydroxyapatite (HA) and poly(-lactide) (PLLA) reinforced by compression forging are biodegradable, bioactive, and have ultrahigh strength. However, foreign body reactions to PLLA and physical irritation can occur when not covered by bone. We aimed to confirm the relationships between the depth of the implanted HA-PLLA threaded pins and the new bone formation. We inserted HA-PLLA composite threaded pins (diameter: 2.0 or 4.5 mm) into the femoral and tibial bones of 32 mature male Japanese white rabbits (weight 3.0-3.5 kg) with the pin head 1 or 0 mm below or protruding 1 or 2 mm above surrounding cortical bone. Eight euthanized rabbits were radiologically and histologically assessed at various intervals after implantation. Bone bridging was complete over pins of both diameters at ~12 weeks, when inserted 1 mm below the surface, but the coverage of the pins inserted at 0 mm varied. Bone was not formed when the pins protruded >1 mm from the bone surface. No inflammation developed around the pins by 25 weeks. However, foreign body reactions might develop if composites are fixed above the bone surface, and intraosseous fixation would be desirable using double-threaded screws or a countersink to avoid screw head protrusion.
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http://dx.doi.org/10.3390/ma14061458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8002476PMC
March 2021

Number of Levels of Spinal Fusion Associated with the Rate of Joint-Space Narrowing in the Hip.

J Bone Joint Surg Am 2021 Jun;103(11):953-960

Department of Orthopedic Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.

Background: Fusion of a joint reportedly increases force in the adjacent joints and leads to progression of arthritis. Whether lumbar spinal fusion increases force in the hip joint and promotes wear of the joint space is unclear. The purpose of this study was to evaluate the rate of joint-space narrowing in the hip following spinal fusion and to examine the effects of the number of levels fused on the joint-narrowing rate.

Methods: We retrospectively reviewed data for patients who underwent lumbar spinal fusion from 2011 to 2018 at our institute. Patients with a previous hip surgery, Kellgren-Lawrence grade ≥II hip osteoarthritis, hip dysplasia, and rheumatoid arthritis were excluded. The rate of joint-space narrowing in the hip was measured in 205 eligible patients (410 hips) following spinal fusion, and the effects of sex, age, body mass index, indication for spinal fusion, laterality, sacral fixation, and number of levels fused on the narrowing rate were examined.

Results: The rate of joint-space narrowing for all patients was 0.114 ± 0.168 mm/year. The narrowing rate for single-level fusion was 0.062 ± 0.087 mm/year, whereas that for fusion of ≥7 levels was 0.307 ± 0.254 mm/year. In the multivariate regression analysis, only the length of fusion (standardized coefficient [SC] = 0.374, p < 0.0001) was associated with an increased narrowing rate. When the narrowing rate was normalized by height, female sex was another risk factor for increased narrowing (SC = 0.109, p = 0.023). Secondary regression modeling performed with patients who underwent spinal fusion for degenerative disc disease showed that the length of fusion (SC = 0.454, p < 0.0001) and female sex (SC = 0.138, p = 0.033) were associated with increased joint-space narrowing.

Conclusions: Longer spinal fusion was associated with the progression of hip joint narrowing following spinal fusion. Surgeons should be aware of the possible increased risk of hip degeneration following spinal fusion and should inform patients of this risk.

Level Of Evidence: Level III. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.20.01578DOI Listing
June 2021

Severity of Myelopathy is Closely Associated With Advanced Age and Signal Intensity Change in Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Nationwide Investigation.

Clin Spine Surg 2021 Mar 23. Epub 2021 Mar 23.

Department of Orthopedic Surgery, Tokyo Medical and Dental University Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Tokyo Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, Saitama Department of Orthopedic Surgery, Kudanzaka Hospital, Chiyadaku Department of Orthopaedic Surgery, Wakayama Medical University Kihoku Hospital, Wakayama Department of Orthopedic Surgery, Hirosaki University Graduate School of Medicine, Aomori Department of Orthopedic Surgery, Niigata University Medicine and Dental General Hospital, Niigata Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, Ibaraki Department of Orthopedics, Jichi Medical University, Tochigi Department of Orthopedic Surgery, Chiba University Graduate School of Medicine, Chiba Department of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo Department of Orthopedic Surgery, Yamaguchi University School of Medicine, Yamaguchi Department of Orthopedic Surgery, Osaka Rosai Hospital, Osaka Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Aichi Department of Orthopaedic Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo Department of Orthopaedic Surgery, Shiga University of Medical Science, Shiga Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences, University of Fukui, Fukui Department of Orthopedic Surgery, Tokyo Medical University, Tokyo Department of Orthopedic Surgery, Imakiire General Hospital, Kagoshimashi Department of Orthopedic Surgery, Graduate School of Medicine, Osaka University, Osaka Department of Orthopaedic Surgery, Kurume University School of Medicine, Fukuoka Department of Orthopedic Surgery, Hamamatsu University School of Medicine, Shizuoka Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa Department of Orthopedic Surgery, University of Yamanashi, Yamanashi Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, Tochigi Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto Department of Orthopedic Surgery, Surgical Science, Tokai University School of Medicine, Kanagawa Department of Orthopaedic Surgery, Tohoku University School of Medicine, Miyagi Department of Orthopedic Surgery, Faculty of Medicine, University of Toyama, Toyama, Japan.

Study Design: Prospective, nationwide case series.

Objective: To identify preoperative factors associated with myelopathy and neurological impairment in patients with cervical ossification of the posterior longitudinal ligament (OPLL).

Summary Of Background Data: Various studies have reported clinical outcomes following the surgical treatment of OPLL. However, there has been no large-scale study of preoperative clinical features in patients with cervical OPLL.

Materials And Methods: Data were prospectively collected from 28 institutions nationwide in Japan. In total, 512 patients with neurological impairment caused by cervical OPLL requiring surgery were enrolled. Basic demographic and clinical data, including age, sex, diabetes status, body mass index, smoking history, and disease duration were collected. C2-7 lordotic angle, canal narrowing ratio, range of motion in flexion-extension at C2-7, and type of OPLL were evaluated on lateral radiographs to identify factors influencing the clinical features of patients with OPLL in whom surgery was planned.

Results: Complete documentation was available for 490 patients (362 male, 128 female). In total, 34 patients had the localized type, 181 had the segmental type, 64 had the continuous type, and 211 had the mixed type. Although there were no significant differences in age, body mass index, disease duration, Japanese Orthopedic Association (JOA) score, and lordotic angle at C2-7 according to the type of OPLL, significant differences were observed in a range of motion at C2-7 and the canal narrowing ratio among the 4 types. Multiple regression analysis revealed that the JOA score was significantly associated with age and signal intensity change on magnetic resonance imaging.

Conclusions: This is the first large-scale, prospective, multicenter case series study to investigate factors influencing preoperative neurological status in patients with OPLL. Age and signal intensity change on magnetic resonance images were significantly associated with JOA score in patients requiring surgery.

Level Of Evidence: Level II.
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http://dx.doi.org/10.1097/BSD.0000000000001164DOI Listing
March 2021

Possible Association of Pedicle Screw Diameter on Pseudoarthrosis Rate After Transforaminal Lumbar Interbody Fusion.

World Neurosurg 2021 Jun 5;150:e155-e161. Epub 2021 Mar 5.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Background: Although pedicle screw sizes may affect the rate of bone union after lumbar fusion surgery, there is currently no supportive clinical evidence.

Methods: Eighty-five patients older than 50 years who underwent single-level L4/5 transforaminal lumbar interbody fusion with posterior pedicle screw (PS) fixation were analyzed. Patients with factors that potentially inhibit bone fusion, such as Parkinson disease, were excluded. Bone union was assessed using computed tomography and dynamic radiographs 1 year after surgery. Explanatory factors considered included sex, age, smoking, bone density, material of the cage, PS diameter (PSD), relative PS length, theoretical maximum PSD (PSD), which was defined as the maximum diameter of the screw that may be inserted without breaking cortical bone around the pedicle, and the filling index, which was defined as the difference between the cross-sectional area of maximum PS and actual PS (PSD 2 - PSD 2). Japanese Orthopaedic Association scores before and 1 year after surgery were evaluated as a clinical outcome.

Results: Nineteen levels were diagnosed as pseudoarthrosis. A multivariate logistic regression analysis identified a larger filling index (P = 0.016) and older age (P = 0.047) as risk factors for pseudoarthrosis. The Japanese Orthopaedic Association score 1 year after surgery and its recovery rate were significantly worse in patients with pseudoarthrosis than in those with fusion.

Conclusions: The selection of an appropriately sized screw is important for achieving rigid fusion after transforaminal lumbar interbody fusion. Preoperative planning using multiplanar reconstruction computed tomography is an important approach for ensuring good clinical results.
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http://dx.doi.org/10.1016/j.wneu.2021.02.117DOI Listing
June 2021

Technical and Conceptual Review on the L5-S1 Oblique Lateral Interbody Fusion Surgery (OLIF51).

Spine Surg Relat Res 2021 18;5(1):1-9. Epub 2020 Jun 18.

Center for Frontier Medical Engineering, Chiba University, Chiba, Japan.

Lumbar lateral interbody fusion (LLIF) has been gaining popularity among the spine surgeons dealing with degenerative spinal diseases while LLIF on L5-S1 is still challenging for its technical and anatomical difficulty. OLIF51 procedure achieves effective anterior interbody fusion based on less invasive anterior interbody fusion via bifurcation of great vessels using specially designed retractors. The technique also achieves seamless anterior interbody fusion when combined with OLIF25. A thorough understanding of the procedures and anatomical features is mandatory to avoid perioperative complications.
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http://dx.doi.org/10.22603/ssrr.2020-0086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7870318PMC
June 2020

Indirect decompression via oblique lateral interbody fusion for severe degenerative lumbar spinal stenosis: a comparative study with direct decompression transforaminal/posterior lumbar interbody fusion.

Spine J 2021 06 2;21(6):963-971. Epub 2021 Feb 2.

Department of Orthopaedic Surgery, Kyoto University, Graduate School of Medicine.

Background Context: Previous studies have shown that oblique lateral interbody fusion (OLIF) can improve neurological symptoms via "indirect decompression." However, data are lacking in terms of its benefits when compared with conventional transforaminal lumbar interbody fusion (TLIF) and/or posterior lumbar interbody fusion (PLIF) approach, especially in patients with severe central canal stenosis.

Purpose: To investigate the clinical outcome of OLIF without posterior decompression versus conventional TLIF and/or PLIF in severe lumbar stenosis diagnosed on preoperative magnetic resonance imaging.

Study Design: Retrospective comparative study.

Patient Sample: Fifty-one patients who underwent OLIF and 41 patients who underwent conventional TLIF and/or PLIF.

Outcome Measures: Clinical outcome score by Japanese Orthopedic Association (JOA) score and radiographic outcomes (disc height and fusion rate on computed tomography scan).

Materials/methods: We retrospectively reviewed 51 patients who underwent OLIF with supplemental percutaneous pedicle screws (55 levels; OLIF group) and 41 patients who underwent conventional TLIF and/or PLIF (47 levels; TPLIF group). The cross-sectional area of the thecal sac was measured preoperatively in OLIF and TPLIF groups, but postoperatively only in the OLIF group. All patients were diagnosed with severe stenosis based on Schizas classification (Grade C or D) on magnetic resonance imaging. We compared radiographic and clinical outcome scores (JOA score) between the 2 groups at 1 year of follow-up. The radiographic evaluation included the fusion status and disc height on computed tomography scan. Surgical data and perioperative complications were also investigated.

Results: The baseline demographic data of the 2 groups were equivalent in preoperative diagnosis, JOA score, and disc height and/or angle. The cross-sectional area significantly increased postoperatively, which confirmed indirect decompressive effect in the OLIF group. The JOA score improved in both groups at the 1-year follow up (76.6% vs. 73.5% improvement rate in the OLIF and TPLIF groups, respectively). The fusion rate at the 1-year follow-up was higher in the OLIF group than in the TPLIF group (87.2% vs. 57.4%). The disc height restoration was also better in the OLIF group. The operative data demonstrated less estimated blood loss and operative time in the OLIF group.

Conclusions: OLIF and conventional TLIF and/or PLIF demonstrated comparable short-term clinical outcomes in the treatment of severe degenerative lumbar stenosis. However, the surgical and radiographic outcomes were better in the OLIF group. Surgeons should choose an appropriate approach on a case by case basis, recognizing the perioperative complications specific to each fusion procedure.
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http://dx.doi.org/10.1016/j.spinee.2021.01.025DOI Listing
June 2021

Predictive Value of Heterogeneously Enhanced Magnetic Resonance Imaging Findings With Computed Tomography Evidence of Calcification for Severe Motor Deficits in Spinal Meningioma.

Neurospine 2021 Mar 4;18(1):163-169. Epub 2020 Dec 4.

Department of Orthopaedic Surgery, Kyoto University, Graduate School of Medicine, Kyoto, Japan.

Objective: Spinal meningioma is mostly benign, but they can exhibit neurological deficit. The relationship between neurological impairment and its radiographic findings, including intratumor magnetic resonance imaging (MRI) gadolinium enhancement and calcification in computed tomography (CT) scan, has not been studied. The purpose of this study was to investigate the association of preoperative image findings with neurological status in spinal meningioma.

Methods: Patients histologically diagnosed with spinal meningioma (n = 24), with an average age of 65.4 years, were included. The patients were classified into 2 groups, the homogeneous and heterogeneous groups, based on the contrast-enhanced T1-weighted MRI findings. Further, baseline demographics (age, sex, presence of preoperative paralysis [manual muscle testing 3 or worse neurological deficit in upper and/or lower limbs], tumor level, tumor length, and tumor occupation ratio), histological findings (Ki-67 index and histological subtypes), and CT findings (presence of intratumor calcification and Hounsfield unit [HU] value) were examined.

Results: Preoperative paralysis was observed in 33.3% (8 of 24) of the patients. These patients exhibited frequent heterogeneous contrast-enhanced MRI findings than those without preoperative paralysis (57.1% vs. 14.3%, p = 0.040). Further, preoperative paralysis did not associate with tumor level, tumor length, tumor-occupied ratio, Ki-67 index, and histological subtypes. The heterogeneous group showed 100% intratumor calcification and higher maximum HU than the homogeneous group (1,109.8 vs. 379.2, p = 0.001).

Conclusion: The heterogeneous contrast-induced MRI findings in the spinal meningioma were significantly associated with preoperative neurological impairment. Moreover, the intratumor contrast-deficient region in the heterogeneously enhanced tumors reflected marked calcification. The tumor hardness due to calcification may be related to preoperative neurological deficit.
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http://dx.doi.org/10.14245/ns.2040494.247DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8021834PMC
March 2021

Rapid Spontaneous Resolution of Lumbar Intraspinal Facet Cyst after Lateral Lumbar Interbody Fusion.

Spine Surg Relat Res 2020 10;4(4):328-332. Epub 2020 Jul 10.

Department of Orthopedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Introduction: Intraspinal facet cysts resistant to conservative treatment are treated surgically. Surgical treatment was generally resection and decompression, but complications of dural tear and recurrence sometimes occurred. We present good clinical results and rapid spontaneous resolution following treatment of five cases of lumbar intraspinal facet cyst after lateral lumbar interbody fusion (LLIF).

Methods: Multicenter series of five cases of lumbar intraspinal facet cyst with segmental instability treated with LLIF. The cross-sectional area (CSA) of the thecal sac and facet cyst on T2-weighted axial magnetic resonance imaging and the distance of facet joint (FJ) gap on axial computed tomography were measured preoperatively and postoperatively. Patient data and clinical and radiographic results were described.

Results: Of five patients, one was male and four were female, with an average age of 72.6 (61-76) years. The mean preoperative CSA of facet cyst was 40.09 mm. In all cases, intraspinal facet cyst resolved within two weeks after LLIF and good clinical results were obtained. The mean CSA of the thecal sac increased from 64.18 mm preoperatively to 95.72 mm postoperatively. The mean distance of FJ gap increased from 0.8 (0-1.5) mm preoperatively to 3.1 (0.5-6.0) mm postoperatively.

Conclusions: LLIF may be indicated for intraspinal facet cysts with segmental instability.
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http://dx.doi.org/10.22603/ssrr.2020-0084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7661029PMC
July 2020

Long-term Radiographic Outcome of Occipitocervical Fixation: An Analysis of Fusion Rate and Spontaneous Subaxial Alignment Change at an Average 7-year Follow-up.

Spine (Phila Pa 1976) 2021 Feb;46(3):152-159

Department of Orthopaedic Surgery, Kyoto University, Graduate School of Medicine, Kyoto, Japan.

Study Design: Retrospective case series.

Objective: The aim of this study was to investigate the long-term radiographic outcome of patients who underwent occipitocervical fixation (OCF) using a modern screw/rod system.

Summary Of Background Data: Few studies have reported fusion rates and radiographic alignment changes in unfused subaxial segments after OCF at a long-term follow-up.

Methods: We retrospectively reviewed 22 patients who underwent OCF with a modern screw-based construct. The patients satisfied the minimum 2-year radiographic follow-up. Baseline demographics and the following pre- and postoperative sagittal alignment parameters were investigated. McGregor slope, O-C2 angle (OC2A), and C2-7 Cobb angle (CL). We grouped patients into those whose OC2A increased postoperatively (OC2A-increase group) and those whose OC2A decreased postoperatively (OC2A-decrease group). The postoperative sagittal alignment change was compared between the 2 groups at the final follow-up. The perioperative complications as well as fusion status based on computed tomography (CT) were investigated.

Results: The average follow-up period was 89.7 months. The lowest instrumented vertebra was at C2 (63.6%), C3 (18.1%), or C4 (18.1%). The fusion rate at the final follow-up was 77.2%. Postoperative dysphasia occurred in two patients (16.6%) in the OC2A-decrease group, whereas distal junctional kyphosis was observed in two patients (20.0%) in the OC2A-increase group. The OC2A-increase group demonstrated a mean 4.8° decrease in CL as a compensation for the 5.1° increase in OC2A. In contrast, the OC2A-decrease group showed a mean 9.2° increase in CL as a compensation for the 6.3° decrease in OC2A.

Conclusion: The CT-confirmed fusion rate of OCF was 77.2% over an average 89.7-month follow-up. Compensatory sagittal alignment change can occur in the unfused subaxial segments in conjunction with the alignment change in the instrumented OC segments, whereas the horizontal gaze was maintained. Strong consideration for the intraoperative measurement of the OC2A should be given during OCF to minimize both early and long-term complications.Level of Evidence: 4.
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http://dx.doi.org/10.1097/BRS.0000000000003757DOI Listing
February 2021

Letter to the Editor concerning "Impact of spinal alignment and stiffness on impingement after total hip arthroplasty: a radiographic study of pre‑ and post‑operative spinopelvic alignment" by Hagiwara S, et al. (Eur Spine J. 2020; doi.org/10.1007/s00586-020-06589-z).

Eur Spine J 2020 12 14;29(12):3245-3246. Epub 2020 Oct 14.

Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo, Kyoto, 606-8507, Japan.

Purpose: Dislocation is one of the remaining challenges after total hip arthroplasty. The spinopelvic mobility is considered to be the key to solve this problem and is of interest both to arthroplasty and spine surgeons. The purpose of this letter is to discuss the spinopelvic mobility and spinal stiffness described in the paper titled "Impact of spinal alignment and stiffness on impingement after total hip arthroplasty: a radiographic study of pre‑ and post‑operative spinopelvic alignment." by Hagiwara S, et al. METHODS: Examining the consistency between this paper and previously published papers on spinopelvic mobility.

Results: In this article, radiographic clearance of anterior impingement was defined as adding of femoral shaft angle and sacral slope (SS), and that of posterior impingement as adding SS and femoral shaft angle subtracting 90º in the sitting position. The impingement itself and other factors for dislocation including implant design, implant orientation, extra-prosthetic impingement and their mobilities are not considered in this parameter, and it is better if the validity of this parameter is shown. The term "rigid spine" and "spinal stiffness" are used in the manuscript. When THA candidates are evaluated, they are categorized according to the flexibility and/or sagittal balance. It would be better if the definition was described in the text and the clearance for impingement was shown to be affected by spinal stiffness.

Conclusion: The conclusions and titles are overstated from the results, but this paper is highly valuable in reminding spinal surgeons of the importance of spinopelvic alignment and mobility in THA.
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http://dx.doi.org/10.1007/s00586-020-06633-yDOI Listing
December 2020

Preserving the Pelvic Ring at the Sciatic Notch During Resection of Malignant Bone Tumors at the Posterior Ilium.

Orthop Surg 2020 Dec 11;12(6):2013-2017. Epub 2020 Oct 11.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Resection of malignant bone tumors in the posterior ilium may result in pelvic ring disruption. Preserving the pelvic ring and keeping an adequate surgical margin is ideal, but is challenging, especially when the tumor extends to the sacroiliac joint. The current report proposes a line from the lateral point of the second sacral dorsal foramen to the anterior surface of sacral ala (S -sacral ala line), and cutting from the line to the ilium over the sciatic notch and to the sacral wing using thread saws. This preserves the cortex at the sciatic notch and the distal sacroiliac joint. Two posterior iliac tumors extending to the sacroiliac joint, a metastatic melanoma in a 75-year-old male, and an osteosarcoma in a 56-year-old male were resected. The resections were performed along the S -sacral ala line, and consequently lumbo-sacro-pelvic fusions were performed. Both patients were able to walk with one crutch. Indications for the method using the S -sacral ala line for iliac tumors may be limited. However, the method can increase pelvic ring preservation in cases with posterior iliac malignant bone tumors.
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http://dx.doi.org/10.1111/os.12783DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7767675PMC
December 2020

Usefulness of model-based iterative reconstruction in low-dose lumbar spine CT after spine surgery with metal implant: a phantom study.

Acta Radiol 2020 Oct 5:284185120961424. Epub 2020 Oct 5.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Background: The major problems of computed tomography (CT) imaging include radiation exposure and severe artifacts caused by operative implants.

Purpose: To evaluate the usefulness of the metal artifact reduction algorithm and model-based iterative reconstruction (MBIR) in postoperative low-dose (LD) spine CT.

Material And Methods: A CT torso phantom was scanned at standard-dose (SD) and LD settings. The CT images were reconstructed by three methods: hybrid iterative reconstruction (HIR); metal artifact reduction; and MBIR. The radiation dose of the phantom imaging was evaluated by volume CT dose index (mGy), dose length product (DLP, mGy × cm), and effective dose (mSv). The image quality of the six images was visually evaluated and analyzed using Scheffe's paired comparison method. The average preference of each method was calculated based on the comparative scores. The task transfer function (TTF) and noise power spectrum for HIR and MBIR were also measured.

Results: The respective radiation-dose-related parameters of the SD and LD conditions were: volume CT dose index = 10.2 and 1.2 mGy; DLP = 277.9 and 33.9 mGy × cm; and effective dose = 4.2 and 0.5 mSv. The average preference for diagnostic acceptability of MBIR at LD was not significantly different from the other reconstructions of SD data. MBIR successfully reduced metal artifacts in the LD condition. The 10% TTF was higher for HIR at SD and higher for MBIR at LD.

Conclusion: MBIR is useful for LD spine CT after spine surgery with metal implant.
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http://dx.doi.org/10.1177/0284185120961424DOI Listing
October 2020

study of antibacterial and osteogenic activity of titanium metal releasing strontium and silver ions.

J Biomater Appl 2021 01 20;35(6):670-680. Epub 2020 Sep 20.

Graduate School of Medicine, Department of Orthopaedic Surgery, Kyoto University, Japan.

Peri-prosthetic infection and loosening of implants are major problems in orthopaedic and dental surgery. To address these issues, surface treatment methods for titanium implants have been improved by modifying the alkali and heat treatment. We have previously fabricated calcium-treated Ti metal that releases Sr ions (CaSr-Ti), which resulted in a higher osteogenic response and early bone bonding.Further, we developed a Ti metal that released both Sr and Ag ions (CaSrAg-Ti). In this study, we evaluated the antibacterial ability and osteogenic cellular response of CaSrAg-Ti and CaSr-Ti using rat bone marrow stromal cells (BMSCs) cultured on implant samples and extract mediums (EMs) made by immersing the implant samples in the medium. CaSrAg-Ti did not show cytotoxicity and was associated with a slightly higher osteogenic response when compared to CaSr-Ti, without inhibiting the effect of Sr. The osteogenic response was also observed in the cells cultured with the CaSrAg-Ti EM; however, the response was not as high as that of the cells on the CaSrAg-Ti implant sample. Significantly higher antibacterial activity was observed along with an antibacterial efficacy of more than 95% against methicillin-susceptible and . The main advantages of our surface treatment are its simplicity and low cost. Therefore, our treatment is promising for clinical applications in orthopaedic or dental Ti-based implants with antibacterial and early bone-bonding abilities.
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http://dx.doi.org/10.1177/0885328220959584DOI Listing
January 2021

Stand-Alone Anterior Cervical Discectomy and Fusion Using an Additive Manufactured Individualized Bioactive Porous Titanium Implant without Bone Graft: Results of a Prospective Clinical Trial.

Asian Spine J 2021 Jun 22;15(3):373-380. Epub 2020 Sep 22.

Department of Orthopedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

The purpose of this study was to introduce our patient-specific bioactive porous titanium implant manufactured using selective laser melting (SLM) and to establish the efficacy and safety of the implant for stand-alone anterior cervical discectomy and fusion (ACDF) based on a prospective clinical trial. We designed a customized ACDF implant using patient-specific data and manufactured the implant using SLM. We produced a bioactive surface through a specific chemical and thermal treatment. Using this implant, we surgically treated four patients with cervical degenerative disc disease and evaluated the clinical and radiological results. We achieved successful bony union in all but one patient without autologous bone grafting within 1 year. We observed no implant subsidence during the follow-up period, and all clinical parameters improved significantly after surgery, with no reported implant-related adverse effects. Our customized bioactive porous titanium implant is a safe and promising implant for stand-alone ACDF.
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http://dx.doi.org/10.31616/asj.2020.0231DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8217843PMC
June 2021

Cervical Myelopathy Caused by Invagination of Floating Anomalous C2 and C3 Laminae in the Spinal Canal.

Spine Surg Relat Res 2020 20;4(3):274-276. Epub 2019 Sep 20.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

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http://dx.doi.org/10.22603/ssrr.2019-0073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447344PMC
September 2019

Accuracy of fluoroscopic guidance with the coaxial view of the pedicle for percutaneous insertion of lumbar pedicle screws and risk factors for pedicle breach.

J Neurosurg Spine 2020 Aug 28:1-8. Epub 2020 Aug 28.

Objective: In this study the authors aimed to evaluate the rate of malposition, including pedicle breach and superior facet violation, after percutaneous insertion of pedicle screws using the coaxial fluoroscopic view of the pedicle, and to assess the risk factors for pedicle breach.

Methods: In total, 394 percutaneous screws placed in 85 patients using the coaxial fluoroscopic view of the pedicle between January 2014 and September 2017 were assessed, and 445 pedicle screws inserted in 116 patients using conventional open procedures were used for reference. Pedicle breach and superior facet violation were evaluated by postoperative 0.4-mm slice CT.

Results: Superior facet violation was observed in 0.5% of the percutaneous screws and 1.8% of the conventionally inserted screws. Pedicle breach occurred more frequently with percutaneous screws (28.9%) than with conventionally inserted screws (11.9%). The breaches in percutaneous screws were minor and did not reduce the interbody fusion rate. The angle difference between the percutaneous and conventionally inserted screws was comparable. Insertion at the L3 or L4 level, right-sided insertion, placement around a trefoil canal, smaller pedicle angle, and a small difference between the screw and pedicle diameters were found to be risk factors for pedicle breach by percutaneous pedicle screws.

Conclusions: Percutaneous pedicle screw placement using the coaxial fluoroscopic view of the pedicle carries a low risk of superior facet violation. The screws should be placed carefully considering the level and side of insertion, canal shape, and pedicle angle.
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http://dx.doi.org/10.3171/2020.5.SPINE20291DOI Listing
August 2020

Bioactivity and antibacterial activity of strontium and silver ion releasing titanium.

J Biomed Mater Res B Appl Biomater 2021 Feb 6;109(2):238-245. Epub 2020 Aug 6.

Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.

To overcome problems associated with loosening of orthopedic implants and surgical site infections, we developed a novel, titanium (Ti)-based material that releases both strontium and silver ions (CaSrAg-Ti) based on alkali-and-heat treatment. The results of commercially pure Ti (cp-Ti), Ti that releases Sr ions only (CaSr-Ti), and the novel CaSrAg-Ti material were compared. Mechanical tests were performed to evaluate the in vivo bonding properties of CaSrAg-Ti and the bone-implant contact (BIC) ratio in histological specimens was determined at 4 and 8 weeks after implantation in a rat femur. Also, the in vitro antibacterial activities of this material against methicillin-susceptible Staphylococcus aureus (MSSA) were evaluated after a 24 h incubation period by assaying colony-forming units. In addition, antibacterial activities were evaluated in vivo at 7 days after implantation in a rat subcutaneous pocket model. There was direct contact between the bone and CaSrAg-Ti in histological specimens and no apparent signs of argyrosis in any rat. The bone-bonding strength and the BIC ratio were increased by 2.7- and 2.3-fold for CaSrAg-Ti vs. cp-Ti at 4 weeks and 2.2- and 2.0-fold at 8 weeks, respectively. As compared with cp-Ti, the number of viable MSSA remaining on CaSrAg-Ti was reduced by 100 ± 0% in vitro and 94.2 ± 6.9% in vivo. Ti that releases Sr and Ag ions is a promising material that exhibits both bone-bonding properties and anti-MSSA activities.
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http://dx.doi.org/10.1002/jbm.b.34695DOI Listing
February 2021

Analysis of the Factors Affecting Lumbar Segmental Lordosis After Lateral Lumbar Interbody Fusion.

Spine (Phila Pa 1976) 2020 Jul;45(14):E839-E846

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Study Design: Retrospective study.

Objective: To elucidate factors that determine segmental lordosis after lateral retroperitoneal lumbar interbody fusion (LLIF) with percutaneous pedicle screw fixation.

Summary Of Background Data: LLIF has been widely used in degenerative lumbar spine surgery. However, the detailed mechanisms that determine segmental lordosis are still unknown.

Methods: A total of 69 patients who underwent LLIF with posterior pedicle screw fixation without posterior osteotomy were analyzed. Computed tomography was performed before and within 2 weeks after surgery, and segmental lordotic angle (SLA) after surgery (Post-SLA) was predicted using multiple regression analysis. Explanatory factors considered in this study included SLA before surgery (Pre-SLA), disc height before surgery (DiscH), cage position (CageP; distance between the center of the cage and the center of the disc, where a positive value indicates an anterior cage position), cage angle (CageA), cage height (CageH), CageH-DiscH (amount of lift up), previous decompression surgery, and level fused.

Results: A total of 102 levels were analyzed. Multiple regression analysis revealed that the Post-SLA can be predicted with three independent variables, CageP, Pre-SLA, and CageH-DiscH and the adjusted R was 0.70. In cases when the cage was located anteriorly (CageP > 3 mm), Post-SLA was greater with larger CageH, larger CageA, and larger Pre-SLA. When the cage was located in the middle (3 mm ≤CageP ≤-1 mm), Post-SLA was greater with larger CageP, larger Pre-SLA, and without previous decompression surgery. If the cage was located posteriorly (CageP < -1 mm), Post-SLA was greater with smaller CageH-DiscH and greater Pre-SLA.

Conclusion: To gain maximum segmental lordosis in LLIF, the cage should be located anteriorly. Furthermore, if the cage can be located anteriorly, a thicker cage with proper angle cage will gain segmental lordosis. If the cage is located posteriorly, a thin cage should be selected.

Level Of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000003432DOI Listing
July 2020

Indirect Decompression Through Oblique Lateral Interbody Fusion for Revision Surgery After Lumbar Decompression.

World Neurosurg 2020 09 23;141:e389-e399. Epub 2020 May 23.

Department of Orthopaedic Surgery, Kyoto University, Graduate School of Medicine, Kyoto, Japan.

Background: Clinical outcome of indirect decompression for a revision surgery, at the same level of a previous lumbar decompression, has not been reported. The purpose of this study was to investigate the efficacy of oblique lateral interbody fusion (OLIF) in revision surgery after decompression for degenerative lumbar spinal disease.

Methods: We included 34 patients who were preoperatively diagnosed with a recurrence of canal stenosis, foraminal stenosis, or intervertebral instability at the same level of a prior lumbar decompression. These patients underwent OLIF with supplemental pedicle screw fixation without additional posterior decompression. All patients completed a minimum 1-year follow-up. We compared the cross-sectional area (CSA) of the thecal sac on magnetic resonance imaging as well as clinical outcome scores (Japanese Orthopaedic Association [JOA] score) preoperatively and at the final follow-up. Fusion status and disc height/angle were evaluated based on computed tomography scans.

Results: The CSA expanded from 136.4 ± 57.9 mm preoperatively to 194.1 ± 58.6 mm at the final follow-up (mean: 27.4 months; P < 0.001). Clinical symptoms significantly improved (59.0% improvement rate of JOA score) at the average of a 17.1-month follow-up. The fusion rate was 93.0%. The disc height was restored (preoperative: 5.7 mm; postoperative: 8.3 mm; P < 0.001), and foraminal stenosis significantly improved postoperatively. There were no major vascular/ureteral injuries.

Conclusions: OLIF at the same level of a prior lumbar decompression provided a successful indirect decompressive effect, including expansion of the thecal sac, restoration of disc height, and subsequent improvement of foraminal stenosis. Specifically, this procedure can prevent incidental durotomy and nerve root injury, which may occur in conventional revision surgeries for direct posterior fusion.
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http://dx.doi.org/10.1016/j.wneu.2020.05.151DOI Listing
September 2020

Repair of Iliac Crest Defects with a Hydroxyapatite/Collagen Composite.

Asian Spine J 2020 Dec 21;14(6):808-813. Epub 2020 May 21.

Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.

Study Design: Retrospective study.

Purpose: This study aimed to assess the effect of refilling with hydroxyapatite/collagen (HAp/Col) composite on an iliac crest defect after spinal fusion.

Overview Of Literature: The use of iliac crest bone graft has been the gold standard in spinal fusion for a long time because of its biological and non-immunologic properties. Few reports have addressed how bone defects recover after iliac crest bone harvest following spinal fusion.

Methods: Cancellous bone was collected from the anterior iliac crest during lateral interbody fusion (LIF), and the bone void of the ilium was refilled with a porous HAp/Col composite. We assessed bone recovery using computed tomography (CT). From the 74 patients who underwent LIF between January 2015 and December 2016, we included 49 patients whose iliac crest could be evaluated using CT at 3 months and 1 year after the surgery.

Results: Bone defects decreased in a time-dependent manner after the surgery. Cortical closure was observed in 28.5% of the cases 3 months after the surgery; at 1 year postoperatively, 95.9% of the patients had cortical closure. Complete repair of the cancellous bone was achieved in 57.1% of the patients at 3 months after the surgery and in 95.9% at 1 year after the surgery. There were no significant hematomas, infections, iliac crest fractures, or soft tissue herniation.

Conclusions: Radiographic recovery of cortical and cancellous bone defects was achieved with high probability via refilling with HAp/Col composite over the 1-year period.
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http://dx.doi.org/10.31616/asj.2019.0310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7788373PMC
December 2020

Incidence and Clinical Features of Postoperative Symptomatic Hematoma after Spine Surgery: A Multicenter Study of 45 Patients.

Spine Surg Relat Res 2020 1;4(2):130-134. Epub 2019 Nov 1.

Department of Orthopaedic Surgery, Kyoto University, Kyoto, Japan.

Introduction: Symptomatic postoperative hematoma after spine surgery is a rare but serious complication. The objective of this study was to investigate the incidence and clinical features of symptomatic postoperative hematoma after spine surgery.

Methods: We retrospectively identified 10,680 patients who underwent spine surgery between 2002 and 2012 in nine hospitals. We reviewed the incidence of postoperative hematoma and its clinical features, including time before onset, main symptoms, and neurological outcomes.

Results: The overall incidence of symptomatic postoperative hematoma after spine surgery was 0.4% (45/10,680). Postoperative hematoma was more frequent after thoracic spine surgery than after cervical or lumbar surgery. The onset of postoperative hematoma occurred at an average of 2.6 days (range 0-14 days) postoperatively. The chief symptoms caused by postoperative hematoma after spine surgery were tetra/paraplegia in 30 patients, hemiplegia in eight patients, intractable pain in five patients, and airway dysfunction in two patients. Surgical evacuation of the spinal epidural hematoma resulted in improvement of at least one grade in 35 patients, while four patients had complete motor paralysis even after evacuation surgery.

Conclusions: We report the clinical details of 45 patients with postoperative hematoma after spine surgery. This information could assist surgeons to make a prompt diagnosis and perform early evacuation surgery for postoperative hematoma following spine surgery.
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http://dx.doi.org/10.22603/ssrr.2019-0080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217683PMC
November 2019

Cervical spinal computed tomography utilizing model-based iterative reconstruction reduces radiation to an equivalent of three cervical X-rays.

Eur Spine J 2020 11 9;29(11):2804-2813. Epub 2020 May 9.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.

Purpose: To evaluate radiation dose and image quality of cervical spinal computed tomography scanned with low-radiation dose (LD-CT) utilizing model-based iterative reconstruction (MBIR).

Methods: We retrospectively examined 14 patients (65.5 ± 13.9 years) who underwent both standard-radiation-dose CT (SD-CT) reconstructed with hybrid iterative reconstruction and LD-CT of cervical spine. The radiation dose, objective image quality indicator, which includes signal-to-noise and contrast-to-noise, and subjective image quality score of the anatomical landmarks in the SD-CT and LD-CT were statistically compared. In addition, the measurement errors of the length of C3 vertebrae (height, anteroposterior length, inner and outer pedicle diameters) between SD-CT and LD-CT were analyzed.

Results: Radiation dose of LD-CT was reduced to one-sixth of the dose of SD-CT. The objective image quality indicator of LD-CT was significantly better than that of SD-CT. The subjective image quality of LD-CT was relatively worse than that of SD-CT but generally graded as clinically accepted or higher. There was no remarkable difference between SD-CT and LD-CT in the measurement value of height and anteroposterior length. Inner pedicle diameter was significantly (0.21 ± 0.13 mm) smaller, and outer pedicle diameter was (0.24 ± 0.14 mm) larger on LD-CT than on SD-CT.

Conclusion: Cervical spinal LD-CT that utilized MBIR enabled radical decrease in radiation dose and provided sufficient image quality for clinical use. This scanning protocol can be a good alternative for protecting patients from exposure to unnecessary radiation, especially when a patient requires multiple CT scans.
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http://dx.doi.org/10.1007/s00586-020-06426-3DOI Listing
November 2020

Bioactive effects of strontium loading on micro/nano surface Ti6Al4V components fabricated by selective laser melting.

Mater Sci Eng C Mater Biol Appl 2020 Apr 5;109:110519. Epub 2019 Dec 5.

Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507, Japan.

Selective laser melting (SLM) titanium alloys require surface modification to achieve early bone-bonding. This study investigated the effects of solution and heat treatment to induce the sustained release of strontium (Sr) ions from SLM Ti6Al4V implants (Sr-S64). The results were compared with a control group comprising an untreated surface [SLM pure titanium (STi) and SLM Ti6Al4V (S64)] and a treated surface to induce the release of calcium (Ca) ions from SLM Ti6Al4V (Ca-S64). The surface-treated materials showed homogenous nanoscale network formation on the original micro-topographical surface and formed bone-like apatite on the surface in a simulated body fluid within 3 days. In vitro evaluation using MC3T3-E1 cells showed that the cells were viable on Sr-S64 surface, and Sr-S64 enhanced cell adhesion-related and osteogenic differentiation-related genes expression. In vivo rabbit tibia model, Sr-S64 provided significantly greater bone-bonding strength and bone-implant contact area than those in controls (STi and S64) in the early phase (2-4 weeks) after implantation; however, there was no statistical difference between Ca-S64 and controls. In conclusion, Sr solution and heat treatment was a safe and effective method to enhance early bone-bonding ability of S-64 by improving the surface characteristics and sustained delivery for Sr.
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http://dx.doi.org/10.1016/j.msec.2019.110519DOI Listing
April 2020

Indirect decompression with lateral interbody fusion for severe degenerative lumbar spinal stenosis: minimum 1-year MRI follow-up.

J Neurosurg Spine 2020 Mar 13:1-8. Epub 2020 Mar 13.

Objective: The use of indirect decompression surgery for severe canal stenosis remains controversial. The purpose of this study was to investigate the efficacy of lateral interbody fusion (LIF) without posterior decompression in degenerative lumbar spinal spondylosis with severe stenosis on preoperative MRI.

Methods: This is a retrospective case series from a single academic institution. The authors included 42 patients (45 surgical levels) who were preoperatively diagnosed with severe degenerative lumbar stenosis on MRI based on the previously published Schizas classification. These patients underwent LIF with supplemental pedicle screw fixation without posterior decompression. Surgical levels were limited to L3-4 and/or L4-5. All patients satisfied the minimum 1-year MRI follow-up. The authors compared the cross-sectional area (CSA) of the thecal sac and the clinical outcome scores (Japanese Orthopaedic Association [JOA] score) preoperatively, immediately postoperatively, and at the 1-year follow-up. Fusion status and disc height were evaluated based on CT scans obtained at the 1-year follow-up.

Results: The CSA improved over time, increasing from 54.5 ± 19.2 mm2 preoperatively to 84.7 ± 31.8 mm2 at 3 weeks postoperatively and to 132.6 ± 37.5 mm2 at the last follow-up (average 28.3 months) (p < 0.001). The JOA score significantly improved over time (preoperatively 16.1 ± 4.1, 3 months postoperatively 24.4 ± 4.0, and 1-year follow-up 25.7 ± 2.9; p < 0.001). The fusion rate at the 1-year follow-up was 88.8%, and disc heights were significantly restored (preoperative, 6.3 mm and postoperative, 9.6 mm; p < 0.001). Patients showing poor CSA expansion (< 200% expansion rate) at the last follow-up had a higher prevalence of pseudarthrosis than patients with significant CSA expansion (> 200% expansion rate) (25.0% vs 3.4%, p < 0.001). No major perioperative complications were observed.

Conclusions: LIF with indirect decompression for degenerative lumbar disease with severe canal stenosis provided successful clinical outcomes, including restoration of disc height and indirect expansion of the thecal sac. Severe canal stenosis diagnosed on preoperative MRI itself is not a contraindication for indirect decompression surgery.
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http://dx.doi.org/10.3171/2020.1.SPINE191412DOI Listing
March 2020

The characteristics of the patients with radiologically severe cervical ossification of the posterior longitudinal ligament of the spine: A CT-based multicenter cross-sectional study.

J Orthop Sci 2020 Sep 29;25(5):746-750. Epub 2019 Oct 29.

Department of Orthopedic Surgery, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, Kyoto, 606-8507, Japan; Japanese Organization of the Study for Ossification of Spinal Ligament (JOSL), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.

Background: Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by heterotopic bone formation in the posterior longitudinal ligament of the spine. We know that the size and distribution of the ossified lesions in patients with OPLL are different in each case. However, the characteristics of the patients with radiologically severe cervical OPLL remain unknown.

Methods: The participants of our study were symptomatic patients with cervical OPLL who were diagnosed by standard radiographs of the cervical spine. Whole-spine CT data and demographic data such as age and sex were obtained from 20 institutions belonging to the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. According to the number of the levels involved by OPLL, we stratified the patients into two subgroups: severe group (S-group) and non-severe group (NS-group) to delineate the characteristics of radiologically severe patients with cervical OPLL. We also evaluated the most compressed level and the degree of occupying ratio of cervical spinal canal by OPLL at the most compressed level.

Results: A total of 234 patients with a mean age of 65 years were recruited. The S-group consisted of 48 patients (21%, 12 females and 36 males) and the NS-group consisted of 92 patients (79%, 22 females and 70 males). The mean age of males in the S-group (68 years old) was significantly higher than that of males in the NS-group (64 years old); however there was no significant difference in the mean age in females between the S-group (69 years old) and the NS-group (66 years old). No significant difference of body mass index, ossification of the nuchal ligament-positivity and presence of diabetes mellitus were found between the S- and the NS-group.

Conclusions: It is likely that the manner of extension of cervical OPLL is different between male and female patients.
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http://dx.doi.org/10.1016/j.jos.2019.09.018DOI Listing
September 2020
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