Heterogeneous osteoimmune profiles via single-cell transcriptomics in osteoporotic patients who fail bisphosphonate treatment.

Postmenopausal osteoporosis arises from imbalanced osteoclast and osteoblast activity, and mounting evidence suggests a role for the osteoimmune system in bone homeostasis. Bisphosphonate (BP) is an antiresorptive agent, but its treatment failure rate can be as high as 40%. Here, we performed single-cell RNA sequencing on peripheral immune cells from carefully selected postmenopausal women: non-osteoporotic, osteoporosis improved after BP treatment, and BP-failed cases. We found an increase in myeloid cells in patients with osteoporosis (specifically, T cell receptor+ macrophages). Furthermore, lymphoid lineage cells varied significantly, notably elevated natural killer cells (NKs) in the BP-failed group. Moreover, we provide fruitful lists of biomarkers within the immune cells that exhibit condition-dependent differences. The existence of osteoporotic- and BP-failure-specific cellular information flows was revealed by cell-cell interaction analysis. These findings deepen our insight of the osteoporosis pathology enhancing comprehension of the role of immune heterogeneity in postmenopausal osteoporosis and BP treatment failure.

Radiological Outcomes of Re-tethering for Adolescent Idiopathic Scoliosis: A 2-to-5-year Follow-Up Case Series After Index Vertebral Body Tethering Failure.

PURPOSE: Vertebral Body Tethering (VBT) has been shown to have a less predictable outcome compared to spinal fusion in patients with adolescent idiopathic scoliosis (AIS). Tether breakage is a common mechanical event that sometimes leads to loss of correction. No data has been published that evaluates the outcome of re-tethering in patients who underwent revision surgery for failed VBT, which was the purpose of this study. METHODS: This is an analysis of a prospectively collected single center database of 290 patients who have had VBT. Patients for this study were included if they have had re-tethering after failed VBT and a minimum follow up of 24 months after index surgery as well as a minimum follow up of 12 months after revision surgery. Revision surgeries included tether exchange, tether reinforcement and/or mono- and bisegmental lateral fusion. Main outcome of interest was curve magnitude at latest follow up. RESULTS: 11 patients were identified who received VBT for 16 curves of which 13 curves have had failed index surgery. Mean follow up from index surgery was 40 months, time between index and revision surgery was 22 months and latest follow up after revision surgery 19 months. Re-tethering resulted in an additional correction of 42% for thoracic and 63% for thoracolumbar curves. These results remained clinically stable with only minor loss of correction at final follow up. No patient underwent or was indicated for spinal fusion. CONCLUSION: Re-tethering is feasible and able to achieve additional correction and a sustainable result.

The efficacy of anterior vertebral body tethering in lenke type 6 curves for adolescent idiopathic scoliosis.

PURPOSE: Spinal fusion is the standard treatment for severe forms of adolescent idiopathic scoliosis (AIS). However, with the lowest instrumented vertebra that is usually located at L3 or L4, patients are prone to develop adjacent segment degeneration in the long term. Vertebral body tethering (VBT) as motion preserving technique has become an alternative for select patients with AIS. Several studies have presented the outcome after thoracic VBT but no study has analyzed the outcome after VBT for Lenke type 6 curves. METHODS: This is a retrospective single center data analysis of patients who have had bilateral VBT for Lenke type 6 curves and a minimum follow up of 24 months. Radiographic analysis was performed on several time points. Suspected tether breakages were additionally analyzed with respect to location and time at occurrence. RESULTS: 25 patients were included. Immediate thoracic curve correction was 55.4% and 71.7% for TL/L curves. Loss of correction was higher for TL/L curves and resulted in a correction rate of 48.3% for thoracic curves and 48.9% for TL/L curves at 24 months post-operatively. 22 patients were suspected to have at least one segment with a tether breakage. Three patients required a re-VBT but no patient received posterior spinal fusion. CONCLUSION: Bilateral VBT for Lenke type 6 curves is feasible and shows a significant curve correction for thoracic and TL/L curves at a minimum of 24 months post-operatively. Tether breakage rate and loss of correction remain an unfavorable observation that needs to be improved in the future.

Early-term outcome of apical fusion with vertebral body tethering for thoracolumbar curves in adolescent idiopathic scoliosis: a preliminary study.

INTRODUCTION: Vertebral body tethering (VBT) has become an alternative option for select patients with idiopathic scoliosis. However, studies have shown a high number of tether breakages, specifically after thoracolumbar (TL) VBT, that can have a negative impact on the outcome, when the breakage occurs within the first year after surgery. In order to overcome this problem, we have started to apply an apical fusion (AF) in combination with TL VBT for select patients. This study aims to analyze the outcome after AF plus VBT. METHODS: This is a retrospective single surgeon's data analysis. All patients were included who have had TL VBT after January 2022 and a follow-up of 12 months. Patients were grouped based on whether they only had VBT or VBT + AF. RESULTS: Twenty-five patients were analyzed (15 VBT, 10 VBT + AF). Both groups showed a significant curve correction for thoracic and TL curves. Minor loss of correction was observed in both groups. A significant difference was seen regarding early tether breakages, which were found in 60% of VBT patients and 10% of VBT + AF patients. CONCLUSION: The preliminary data shows a significant reduction of early tether breakages when TL VBT is applied in combination with AF.

Risk factors for mechanical complications after fusion extension surgery for lumbar adjacent segment disease.

PURPOSE: Adjacent segment disease (ASD) is a common complication in fusion surgery. In the event of solid segmental fusion, previous implants can be removed or preserved during fusion extension for ASD. To compare the surgical outcomes of patients with and without implants and analyzes the risk factors for postoperative mechanical complications. METHODS: Patients who underwent fusion extension for lumbar ASD from 2011 to 2019 with a minimum 2 year follow-up were retrospectively reviewed. Spinopelvic parameters were measured preoperatively and postoperatively. Clinical outcomes and surgical complications were compared between groups with implants preserved and removed. Risk factors for mechanical complications, including clinical, surgical, and radiographic factors were analyzed. RESULTS: Sixty-nine patients (mean age, 69.9 ± 6.9 years) were included. The mean numbers of initial and extended fused segments were 2.8 ± 0.7 and 2.7 ± 0.7, respectively. Previous implants were removed in 43 patients (R group) and preserved in 26 patients (P group). Both groups showed an improvement in clinical outcomes without between-group differences. The operation time was significantly longer in R group (260 vs 207 min, p < 0.001). Mechanical complications occurred in 13 patients (12 in R group and 1 in P group) and reoperation was needed in 3 patients (R group). Implant removal, index fusion surgery including L5-S1, and postoperative sagittal malalignment were risk factors for mechanical complications. CONCLUSION: Implant removal was a risk factor for mechanical complications. Index fusion surgery including L5-S1 and postoperative sagittal malalignment were also risk factors for mechanical complications.

Assessing the Reproducibility of the Structured Abstracts Generated by ChatGPT and Bard Compared to Human-Written Abstracts in the Field of Spine Surgery: Comparative Analysis.

BACKGROUND: Due to recent advances in artificial intelligence (AI), language model applications can generate logical text output that is difficult to distinguish from human writing. ChatGPT (OpenAI) and Bard (subsequently rebranded as "Gemini"; Google AI) were developed using distinct approaches, but little has been studied about the difference in their capability to generate the abstract. The use of AI to write scientific abstracts in the field of spine surgery is the center of much debate and controversy. OBJECTIVE: The objective of this study is to assess the reproducibility of the structured abstracts generated by ChatGPT and Bard compared to human-written abstracts in the field of spine surgery. METHODS: In total, 60 abstracts dealing with spine sections were randomly selected from 7 reputable journals and used as ChatGPT and Bard input statements to generate abstracts based on supplied paper titles. A total of 174 abstracts, divided into human-written abstracts, ChatGPT-generated abstracts, and Bard-generated abstracts, were evaluated for compliance with the structured format of journal guidelines and consistency of content. The likelihood of plagiarism and AI output was assessed using the iThenticate and ZeroGPT programs, respectively. A total of 8 reviewers in the spinal field evaluated 30 randomly extracted abstracts to determine whether they were produced by AI or human authors. RESULTS: The proportion of abstracts that met journal formatting guidelines was greater among ChatGPT abstracts (34/60, 56.6%) compared with those generated by Bard (6/54, 11.1%; P<.001). However, a higher proportion of Bard abstracts (49/54, 90.7%) had word counts that met journal guidelines compared with ChatGPT abstracts (30/60, 50%; P<.001). The similarity index was significantly lower among ChatGPT-generated abstracts (20.7%) compared with Bard-generated abstracts (32.1%; P<.001). The AI-detection program predicted that 21.7% (13/60) of the human group, 63.3% (38/60) of the ChatGPT group, and 87% (47/54) of the Bard group were possibly generated by AI, with an area under the curve value of 0.863 (P<.001). The mean detection rate by human reviewers was 53.8% (SD 11.2%), achieving a sensitivity of 56.3% and a specificity of 48.4%. A total of 56.3% (63/112) of the actual human-written abstracts and 55.9% (62/128) of AI-generated abstracts were recognized as human-written and AI-generated by human reviewers, respectively. CONCLUSIONS: Both ChatGPT and Bard can be used to help write abstracts, but most AI-generated abstracts are currently considered unethical due to high plagiarism and AI-detection rates. ChatGPT-generated abstracts appear to be superior to Bard-generated abstracts in meeting journal formatting guidelines. Because humans are unable to accurately distinguish abstracts written by humans from those produced by AI programs, it is crucial to exercise special caution and examine the ethical boundaries of using AI programs, including ChatGPT and Bard.

The neuro-protective role of telomerase via TERT/TERF-2 in the acute phase of spinal cord injury.

PURPOSE: To investigate the interaction of telomerase activity and telomere length on neuro-protection or neuro-degeneration effects after spinal cord injury (SCI). METHODS: A contusive SCI model was developed using 56 Sprague-Dawley rats. Seven rats were allocated into acute injury phase groups (1, 3, 8, 24, and 48 h), and sub-acute and chronic injury phase groups (1, 2, and 4 weeks). Telomerase activity was assessed by telomerase reverse transcriptase (TERT) and telomeric repeat binding factor-2 (TERF-2). Differentiation of activated neural stem cells was investigated by co-expression of neuronal/glial cell markers. Apoptosis expression was also investigated by caspase-3, 8, and 9 using terminal deoxynucleotidyl transferase dUTP nick end labelling staining. Immunofluorescence staining and western blotting were performed for quantitative analyses. RESULTS: Expression of TERT increased gradually until 24 h post-injury, and was decreased following SCI (P < 0.05). TERF-2 also was increased following SCI until 24 h post-injury and then decreased with time (P < 0.05). Co-localization of TERT and TERF-2 was higher at 24 h post-injury. High expression of TERT was seen in neurons (Neu N Ab), however, expression of TERT was relatively lower in astrocytes and oligodendrocytes. Apoptosis analysis showed persistent high expression of caspases-3, -9, and -8 during the observation period. CONCLUSIONS: Increased TERT and TERF-2 activity were noted 24 h post-injury in the acute phase of SCI with TERF-2 maintaining telomeric-repeat length. Our results suggest that increased activity of telomere maintenance may be related to neuro-protective mechanisms against subsequent apoptosis resulting from DNA damage after acute SCI.

Significance of paraspinal muscle quality in risk between single and multiple osteoporotic vertebral fractures.

PURPOSE: To compare paraspinal muscle quality between patients with single and multiple osteoporotic vertebral fractures (OVFs) and evaluate the role of the paraspinal muscles in OVFs. METHODS: A total of 262 consecutive patients with OVFs were retrospectively analyzed in two groups: those with single OVF (n = 173) and those with multiple OVFs (n = 89). The cross-sectional area (CSA) and fatty degeneration of the paraspinal muscles were calculated from axial T2-weighted magnetic resonance imaging at the level of the L4 upper endplate by manual tracing in ImageJ software. Pearson's correlation analysis was performed to analyze correlations of paraspinal muscle quality to multiple OVFs. RESULTS: FD in all the paraspinal muscles was significantly higher in the multiple OVF group than the single OVF group (all p < 0.005). The functional CSA (fCSA) of the paraspinal muscles was significantly lower in the multiple OVF group than the single OVF group (all Ps < 0.001), except for the erector spine (p = 0.304). The Pearson's correlation analysis showed significant positive inter-correlations for the fCSAs of all the paraspinal muscles and the occurrence of multiple OVFs. CONCLUSIONS: The pure muscle volumes of the multifidus, psoas major, and quadratus lumborum were lower in patients with multiple OVFs than in those with a single OVF. Furthermore, the inter-correlation among all the paraspinal muscles indicate that the muscle-bone crosstalk profoundly existed in vertebral fracture cascade. Therefore, special attention to paraspinal muscle quality is needed to prevent progression to multiple OVFs.

Fusion rates based on type of bone graft substitute using minimally invasive scoliosis surgery for adolescent idiopathic scoliosis.

BACKGROUND: Minimally invasive scoliosis surgery (MISS) is currently introduced on novel technique for surgical treatment of adolescent idiopathic scoliosis (AIS). This study is aimed to evaluate the efficacy of facet fusion in MISS compared to posterior fusion in conventional open scoliosis surgery (COSS) and compare facet fusion rates based on three bone graft substitutes in MISS for adolescent idiopathic scoliosis (AIS). METHODS: Eighty six AIS patients who underwent scoliosis surgery were divided into two groups: the COSS group and the MISS group. COSS was performed through posterior fusion with allograft. MISS was applied via facet fusion with three bone graft substitutes. The MISS group was further divided into three subgroups based on graft substitute: Group A (allograft), Group B (demineralized bone matrix [DBM]), and group C (demineralized cancellous bone chips). Fusion rate was measured using conventional radiographs to visualize loss of correction > 10°, presence of lysis around implants, breaks in fusion mass, and abnormal mobility of the fused segment. RESULTS: The fusion rates showed no significant difference in COSS and MISS groups (p = 0.070). In the MISS group, the fusion rates were 85, 100, and 100% in groups A, B, and C, respectively, with no significant difference (p = 0.221). There were no statistical differences between groups A, B, and C in terms of correction rate, fusion rate, and SRS-22 scores (p > 0.05). CONCLUSIONS: The facet fusion in MISS showed comparable to posterior fusion in COSS with regard to radiological and clinical outcomes. Furthermore, the type of graft substitute among allograft, DBM, and demineralized cancellous bone chips did not affect facet fusion rate or clinical outcomes in MISS. Therefore, MISS showed comparable fusion rate (with no influences on the type of graft substitute) and clinical outcomes to those of COSS in the surgical treatment of AIS.

Osteobiologies for Spinal Fusion from Biological Mechanisms to Clinical Applications: A Narrative Review.

Degenerative lumbar spinal disease (DLSD), including spondylolisthesis and spinal stenosis, is increasing due to the aging population. Along with the disease severity, lumbar interbody fusion (LIF) is a mainstay of surgical treatment through decompression, the restoration of intervertebral heights, and the stabilization of motion segments. Currently, pseudoarthrosis after LIF is an important and unsolved issue, which is closely related to osteobiologies. Of the many signaling pathways, the bone morphogenetic protein (BMP) signaling pathway contributes to osteoblast differentiation, which is generally regulated by SMAD proteins as common in the TGF-ß superfamily. BMP-2 and -4 are also inter-connected with Wnt/ß-catenin, Notch, and FGF signaling pathways. With the potent potential for osteoinduction in BMP-2 and -4, the combination of allogenous bone and recombinant human BMPs (rhBMPs) is currently an ideal fusion material, which has equalized or improved fusion rates compared to traditional materials. However, safety issues in the dosage of BMP remain, so overcoming current limitations will provide significant advancement in spine surgery. In the future, translational research and the application of clinical study will be important to overcome the current limitations of spinal surgery.

Are the Choice of Frame and Intraoperative Patient Positioning Associated With Radiologic and Clinical Outcomes in Long-instrumented Lumbar Fusion for Adult Spinal Deformity?

BACKGROUND: Previous studies of patient positioning during spinal surgery evaluated intraoperative or immediate postoperative outcomes after short-instrumented lumbar fusion. However, patient positioning during long-instrumented fusion for an adult spinal deformity (ASD) might be associated with differences in intraoperative parameters such as blood loss and longer-term outcomes such as spine alignment, and comparing types of surgical tables in the context of these larger procedures and evaluating longer-term outcome scores seem important. QUESTIONS/PURPOSES: (1) Do blood loss and the number of transfusions differ between patients who underwent multi-level spinal fusion with a Wilson frame and those with a four-poster frame? (2) Does restoration of lumbar lordosis and the sagittal vertical axis differ between patients who underwent surgery with the use of one frame or the other? (3) Do clinical outcomes as determined by Numeric Rating Scale and Oswestry Disability Index scores differ between the two groups of patients? (4) Are there differences in postoperative complications between the two groups? METHODS: Among 651 patients undergoing thoracolumbar instrumented fusion between 2015 and 2018, 129 patients treated with more than four levels of initial fusion for an ASD were identified. A total of 48% (62 of 129) were eligible; 44% (57 of 129) were excluded because of a history of fusion, three-column osteotomy, or surgical indications other than degenerative deformity, and another 8% (10 of 129) were lost before the minimum 2-year follow-up period. Before January 2017, one surgeon in this study used only a Wilson frame; starting in January 2017, the same surgeon consistently used a four-poster frame. Forty patients had spinal fusion using the Wilson frame; 85% (34 of 40) of these had follow-up at least 2 years postoperatively (mean 44 ± 13 months). Thirty-two patients underwent surgery using the four-poster frame; 88% (28 of 32) of these were available for follow-up at least 2 years later (mean 34 ± 6 months). The groups did not differ in terms of age, gender, BMI, type of deformity, or number of fused levels. Surgical parameters such as blood loss and the total amount of blood transfused were compared between the two groups. Estimated blood loss was measured by the amount of suction drainage and the amount of blood that soaked gauze. The decision to transfuse blood was based on intraoperative hemoglobin values, a protocol that was applied equally to both groups. Radiologic outcomes including sagittal parameters and clinical outcomes such as the Numerical Rating Scale score for back pain (range 0-10; minimal clinically important difference [MCID] 2.9) and leg pain (range 0-10; MCID 2.9) as well as the Oswestry Disability Index score (range 0-100; MCID 15.4) were also assessed through a longitudinally maintained database by two spine surgeons who participated in this study. Repeated-measures analysis of variance was used to compare selected radiologic outcomes between the two groups over time. RESULTS: Blood loss and the total amount of transfused blood were greater in the Wilson frame group than in the four-poster frame group (2019 ± 1213 mL versus 1171 ± 875 mL; mean difference 848 [95% CI 297 to 1399]; p = 0.003 for blood loss; 1706 ± 1003 mL versus 911 ± 651 mL; mean difference 795 [95% CI 353 to 1237]; p = 0.001 for transfusion). Lumbar lordosis and the sagittal vertical axis were less restored in the Wilson frame group than in the four-poster frame group (7° ± 10° versus 18° ± 14°; mean difference -11° [95% -17° to -5°]; p < 0.001 for lumbar lordosis; -22 ± 31 mm versus -43 ± 27 mm; mean difference 21 [95% CI 5 to 36]; p = 0.009 for the sagittal vertical axis). Such differences persisted at 2 years of follow-up. The proportion of patients with the desired correction was also greater in the four-poster frame group than in the Wilson frame group immediately postoperatively and at 2 years of follow-up (50% versus 21%, respectively; odds ratio 3.9 [95% CI 1.3 to 11.7]; p = 0.02; 43% versus 12%, respectively; odds ratio 5.6 [95% CI 1.6 to 20.3]; p = 0.005). We found no clinically important differences in postoperative patient-reported outcomes including Numeric Rating Scale and Oswestry Disability Index scores, and there were no differences in postoperative complications at 2 years of follow-up. CONCLUSION: The ideal patient position during surgery for an ASD should decrease intra-abdominal pressure and induce lordosis as the abdomen hangs freely and hip flexion is decreased. The four-poster frame appears advantageous for long-segment fusions for spinal deformities. Future studies are needed to extend our analyses to different types of spinal deformities and validate radiologic and clinical outcomes with follow-up for more than 2 years. LEVEL OF EVIDENCE LEVEL: III, therapeutic study.

Relationship between degree of separation of endplate cartilage and severity of intervertebral disc herniation.

Degeneration of intervertebral disc and fissures in the anulus was caused by compression and distraction, which lead to nucleus pulposus herniation. However, controversy remains regarding the exact mechanism behind disc herniation. The aim of this study is to analyze histologically the differences between the three types of disc herniations in an attempt to infer the underlying mechanism. Disc samples extracted from 49 patients who underwent discectomy of the lumbar region were studied by histological analysis. The severity of disc herniation was classified as bulging, protrusion, extrusion, or sequestration based on preoperative magnetic resonance imaging measurements. For comparative analysis of sequestration characteristics, 49 patients were classified into either the sequestration or the non-sequestration group (i.e., protrusion and extrusion) according to disc herniation type. Forty of the 49 patients had cartilage present in their disc samples upon histological analysis. The endplate cartilage-containing samples included two of four (50%) protruded disc patients, 22 of 29 (75.9%) extruded disc patients, and 16 of 16 (100%) sequestrated disc patients and had statistical significance (p = 0.019). There were no significant differences in age, sex, body mass index, length of hospital stays, injection history, surgical methods, and Visual Analog Scale between the sequestration and non-sequestration group (all p > 0.05). Separation of endplate cartilage increased with the severity of disc herniation. Therefore, the mechanism of disc herniation should consider the connection with endplate cartilage as an initiating link in the mechanical failure of intervertebral discs.

Surgical outcomes of two kinds of demineralized bone matrix putties/local autograft composites in instrumented posterolateral lumbar fusion.

BACKGROUND: This study aimed to assess the surgical outcomes of two kinds of demineralized bone matrix (DBM) putties/local autograft composites in instrumented posterolateral lumbar fusion (PLF). METHODS: Twenty-seven fusion segments of 19 patients, who underwent decompression and instrumented PLF for lumbar spinal stenosis or degenerative spondylolisthesis less than grade 1, were included in this study. The PLF mass consisted of different two kinds of DBMs (Grafton® and DBX®) and local autograft. Next, 7.5 cc of Grafton® DBM/local autograft composite was implanted on the left side, and the same amount of DBX® DBM/local autograft composite was implanted on the right side in the same patient. The PLF masses of 54 total sides (27 Grafton® sides and 27 DBX® sides) were assessed for fusion based on both flexion/extension lateral radiographs and computed tomography images at 12 and 24 months postoperatively. Clinical symptoms were also evaluated. RESULTS: At 12 months postoperatively, the fusion rates for the Grafton® and DBX® sides were 59.5 and 51.9%, respectively; the difference was not statistically significant (P = 0.425). At 24 months postoperatively, the fusion rates for the Grafton® and DBX® sides increased to 70.4 and 66.7%, respectively, but the difference was still not statistically significant (P = 0.574). Diabetes mellitus, smoking, and obesity (body mass index ≥25) negatively affected the fusion rate of both the Grafton® and DBX® sides. Visual analog scores for lower back pain and leg pain and Oswestry Disability Index were significantly improved after surgery (both, P < 0.01). No deep or superficial infections occurred postoperatively. No patients underwent revision surgery due to nonunion during follow-up. CONCLUSIONS: Our results suggest that two kinds of DBMs/local autograft composites might be considered as useful bone graft substitute in instrumented posterolateral fusion for lumbar spinal stenosis or degenerative spondylolisthesis less than grade 1.

15-year survivorship analysis of an interspinous device in surgery for single-level lumbar disc herniation.

BACKGROUND: Interspinous devices have been introduced as alternatives to decompression or fusion in surgery for degenerative lumbar diseases. This study aimed to investigate 15-year survivorship and risk factors for reoperation of a Device for Intervertebral Assisted Motion (DIAM) in surgery for 1-level lumbar disc herniation (LDH). METHODS: A total of 94 patients (54 men and 40 women) underwent discectomy and DIAM implantation for 1-level LDH, with a mean follow-up of 12.9 years (range, 6.3-15.3 years). The mean age was 46.2 years (range, 21-65 years). Sixty-two patients underwent DIAM implantation for L4-5, 27 for L5-6, and 5 for L3-4. Reoperations due to any reason associated with DIAM implantation level or adjacent levels were defined as failure and used as the end point of determining survivorship. RESULTS: During the 15-year follow-up, 8 patients (4 men and 4 women) underwent reoperation due to recurrence of LDH at the DIAM implantation level, a reoperation rate of 8.5%. The mean time to reoperation was 6.5 years (range, 0.8-13.9 years). Kaplan-Meier analysis showed a cumulative survival rate of the DIAM implantation of 97% at 5 years, 93% at 10 years, and 92% at 15 years after surgery; the cumulative reoperation rate of the DIAM implantation was 3% at 5 years, 7% at 10 years, and 8% at 15 years after surgery. Mean survival time was predicted to be 14.5 years (95% CI, 13.97-15.07). The log-rank test and Cox proportional hazard model showed that age, sex, and location did not significantly affect the reoperation rate of DIAM implantation. CONCLUSIONS: Our results showed that DIAM implantation significantly decreased reoperation rate for LDH in the 15-year survivorship analysis. We suggest that DIAM implantation could be considered a useful intermediate step procedure for LDH surgery. To the best of our knowledge, this is the longest follow-up study in which surgical outcomes of interspinous device surgery were reported.

Rapidly progressive gas-forming infection involving the spine as a life-threatening fatal condition : a case report.

BACKGROUND: Gas forming infection of the spine is a consequence of vertebral osteomyelitis, necrotizing fasciitis, or a gas-forming epidural abscess, which is very rare and fatal conditions. This is the rare case of necrotizing fasciitis that rapidly progressed from the lumbar area to upper thoracic area. CASE PRESENTATION: A 58-year-old male complained of lower back pain with fever and chills. The patient had a history of uncontrolled diabetes mellitus without diabetic medication over the previous 3 months, and he had received several local injections around the lumbar area. Laboratory data revealed white blood cell count of 19,710 /mm3, erythrocyte sedimentation of 40 mm/h, and C-reactive protein of 30.7 mg/L. Radiological findings revealed a small amount of air bubbles in the paraspinal area and lumbar epidural spaces. The patient refused emergency surgery and was discharged from the hospital. The patient re-visited the emergency department two days after discharge complaining of more severe back pain with persistent fever, and his vital signs had deteriorated, with low blood pressure and tachycardia. K. pneumoniae was isolated in cultures from ultrasound-guided aspirates and peripheral blood. The follow-up radiographs revealed aggressive dissemination of innumerable air bubbles from the lumbar area to the T5 level. The patient underwent emergent decompressive laminectomy and debridement of infected paravertebral fascia and musculature. Despite intensive care for deteriorated vital signs and his back wound, the patient died on postoperative day 3 due to multi-organ failure. CONCLUSIONS: Necrotizing fasciitis involving the spine is a very rare disease with life-threatening conditions, rapid progression, and a high mortality rate. Therefore, prompt surgical treatment with a high index of suspicion is imperative to prevent potentially fatal conditions in similar extremely rare cases.

Hyperacute onset of adjacent segment disease with dorsally migrated herniated nucleus pulposus causing cauda equina syndrome: a case report.

PURPOSE: To report the first case of hyperacute onset of adjacent segmental disease (ASD) with dorsally migrated herniated nucleus pulposus (HNP) causing cauda equina syndrome. METHODS: A 55-year-old female complained of lower back pain with radiating pain in both lower extremities that had not responded to conservative treatment over the previous six months. Plain radiographs and magnetic resonance imaging (MRI) findings revealed degenerative spondylolisthesis with spinal stenosis at L3-4, L4-5, and a slight bulging disc at L2-3. The patient underwent decompressive total laminectomy and posterior fusion at L3-4 and L4-5. The stenotic symptoms improved significantly after surgery, and she was then discharged on postoperative day 7. RESULTS: However, the patient visited the emergency department four days after discharge (postoperative day 11) complaining of sudden onset of bilateral lower extremity weakness and voiding and defecation difficulties. The follow-up MRI showed dorsally migrated huge HNP and a detached posterior longitudinal ligament (PLL) at L2-3, which was diagnosed as hyperacute onset of ASD causing cauda equina syndrome. The patient underwent an emergency second operation consisting of partial laminectomy at L2-3 with removal of the dorsally migrated huge HNP. After the second operation, the symptoms of cauda equina syndrome improved. One year after the second operation, the patient is doing well without recurrence of symptoms. CONCLUSIONS: Our case showed that hyperacute onset of ASD with dorsally migrated huge HNP can cause cauda equina syndrome, even within 2 weeks after lumbar fusion surgery. Therefore, a high index of suspicion, timely diagnosis, and surgical treatment are needed to avoid the catastrophic neurologic complications in similar extremely rare cases.

Relationship between iliac screw loosening and proximal junctional kyphosis after long thoracolumbar instrumented fusion for adult spinal deformity.

PURPOSE: Authors assumed that the stability of iliac screw (IS) fixation could affect the development of proximal junctional kyphosis (PJK). The purpose of this study was to analyze the relationship between IS loosening and PJK after long fusion surgery for adult spinal deformity (ASD). METHODS: Sixty-eight ASD patients (6 males, 62 females; mean age, 68.1 years) who underwent long fusion surgery with IS fixation were reviewed. The incidence and risk factors of IS loosening were investigated. The relationship between IS loosening and PJK was also analyzed. RESULTS: IS loosening and PJK appeared in 33 and 19 patients, respectively. The median time for IS loosening and PJK to develop was 6.0 months (range 1.3-59.2) and 9.1 months (range 1.3-73.2), respectively. PJK developed in patients without IS loosening more frequently than in patients with IS loosening. PJK did not develop in 28 patients who presented with IS loosening first. IS loosening developed 5 months postoperatively in those 28 patients, whereas IS loosening was present 11 months postoperatively in 4 patients who presented with PJK first. Preoperative PT (OR = 1.091) and IS loosening (OR = 0.343) were significantly related with the development of PJK. IS loosening was significantly associated with postoperative PI-LL > 10° (OR = 0.957), postoperative SVA (OR = 1.023), and postoperative PT (OR = 1.072). CONCLUSION: Postoperative sagittal malalignment should be avoided to prevent IS loosening and PJK. IS loosening occurred earlier than PJK and seemed to affect the development of PJK. This relationship supports the hypothesis that distal stability of long constructs may increase proximal junctional stress. LEVEL OF EVIDENCE: III. These slides can be retrieved under Electronic Supplementary Material.

Safety and effectiveness of minimally invasive scoliosis surgery for adolescent idiopathic scoliosis: a retrospective case series of 84 patients.

PURPOSE: The aim of this study was to retrospectively evaluate a prospective series of patients with adolescent idiopathic scoliosis (AIS) who were treated with minimally invasive scoliosis surgery (MISS) technique with a minimum follow-up more than 1 year. MATERIALS AND METHODS: We retrospectively analyzed the prospectively collected data of 84 patients with AIS treated with MIS technique using two or three coin hole size incisions and a muscle-splitting approach. The clinical and radiological data such as the correction of deformity, coronal and sagittal profile and record of the perioperative morbidity of the patients were analyzed. RESULTS: The mean primary Cobb angle was corrected from 59.8° preoperatively to 18.6° postoperatively with a mean correction of 68.9% (p < 0.001). The mean kyphosis at T2 to T12 was maintained within normal range with an increase from 31.2° preoperatively to 35.3° postoperatively (p < 0.001). The 30-day perioperative complication rate was 7.14% with one deep infection and five cases of hemothorax. The mean operation time was 312.8 min; mean estimated blood loss was 846.6 ml (range 420-2800); and mean length of stay was 8.5 days (range 5 to 14). All data of postoperative SRS-22 questionnaire were significantly improved (p < 0.001). CONCLUSION: MISS used for AIS provides adequate correction in both planes and acceptable rate of perioperative complications, with a low estimated blood loss and short length of stay. Considering all the positives, the application of MISS technique for AIS seems meaningful and can become a valid alternative to posterior approach in the routine use. These slides can be retrieved under Electronic Supplementary Material.

Cervical myelopathy due to subaxial calcium pyrophosphate dihydrate (CPPD) deposition with simultaneous asymptomatic crowned dens syndrome: two case reports.

BACKGROUND: There are few reports of cervical myelopathy caused by an attack of subaxial calcium pyrophosphate dihydrate (CPPD) deposition. Moreover, there has been no report on cervical myelopathy by subaxial CPPD deposition with simultaneous asymptomatic crowned dens syndrome (CDS) at the same time. CASE PRESENTATION: The first case was a 68-year-old male complaining of cervical myelopathic symptoms. Plain radiographs, computed tomography (CT) and magnetic resonance imaging (MRI) findings revealed spinal cord compression by calcified round lesions at C4 as well as a calcified lesion behind the dens. The second case was a 77-year-old female complaining of cervical myelopathic symptoms. Plain radiographs, CT and MRI findings revealed spinal cord compression by calcified round lesions at C3 and C4 as well as a calcified lesion behind the dens. In both cases, we believed that the calcified lesion behind the dens was an asymptomatic lesion. Therefore, the first patient received decompressive laminectomy of C3 and C4, removal of calcified round lesions, and posterior fixation from C3 to C5 due to associated kyphosis. The second patient underwent decompressive laminectomy of C3 and C4 and removal of calcified round lesions. Microscopic examination under polarized light showed dark blue calcifications with rhomboid crystals that were positively birefringent. The findings were consistent with those of CPPD. CONCLUSIONS: This is the first study to report cervical myelopathy caused by subaxial CPPD deposition with simultaneous asymptomatic CDS. Surgical removal of the subaxial CPPD deposition alone achieved a satisfactory surgical outcome without recurrence.

The impact of COVID-19 pandemic on orthopaedic resident education: a nationwide survey study in South Korea.

PURPOSE: There have not been well-designed survey studies investigating the impact of the coronavirus disease 2019 (COVID-19) pandemic on orthopaedic resident education. METHODS: A 58-question, web-based survey was administered to orthopaedic residents in South Korea. A total of 229 orthopaedic residents from 43 hospitals completed the survey questionnaire. RESULTS: The average working time of 72.7 hours/week before the pandemic was decreased to 65.6 hours/week during the pandemic (p < 0.001). The time working in the operating room was significantly decreased during the pandemic, but not in the emergency centre and outpatient clinic. The education times for lecture and clinical case discussion were decreased during the pandemic (both, p < 0.001), respectively. While the use of traditional teaching methods was decreased, the use of online-based teaching methods was increased (p < 0.001). However, satisfaction level with online-based teaching methods was significantly lower compared with that of traditional teaching methods. The average working time exposed to the patients with COVID-19 was 9.7 hours/week. About 47.6% of orthopaedic residents experienced isolation or quarantine. The average score for quality of life, which was 68.9 out of 100 scores before the pandemic, decreased to 61.7 during the pandemic (p < 0.001). The most stressful factor for orthopaedic residents during the pandemic was family/relative health, followed by their own health and residency program. CONCLUSION: The COVID-19 pandemic had a significant impact on orthopaedic resident education in South Korea. Therefore, flexible and sustainable strategies are necessary to prepare for the future as well as the current pandemic situation.