Objective: To summarize the main findings from research on measuring the value in spine surgery.

Summary of Background Data: Determining the value of surgical interventions, which is defined by the quality and efficacy of care received divided by the cost to deliver healthcare, is inherently complex. The two most fundamental components of value-quality and total cost-are multifactorial and difficult to quantify.

Methods: A narrative review of all the relevant papers known to the author was conducted.

Results: It is straightforward to calculate the aggregate hospital cost following a surgical procedure, but it is not simple to estimate the total cost of a procedure-including the direct and indirect costs. These individual metrics can help providers make more educated decisions with regards to improving patient quality of life and minimizing unnecessary costs. A consensus of the appropriate cost-per-quality-adjusted life-year threshold of different spine surgeries needs to be established. As these metrics become more commonplace in spine surgery, the potential for personalized health care will continue to be developed.

Conclusions: As the healthcare system shifts toward value-based care, there is a substantial need for research assessing the value as defined by the quality and efficacy of care received divided by the cost to deliver healthcare of specific spine surgery procedures. Studies on different predictors-both patient-specific and surgical-that may influence outcomes, cost, and value are required.

Proprioception is a deep sensation that perceives the position of each part of the body, state of movement and muscle contraction, and resistance and mass applied to the body. Proprioceptive feedback influences movement and positional accuracy, resulting in key somatosensory functions for human postural control. Proprioception encompasses signals received from proprioceptors located in the skin, subcutaneous tissue, muscles, tendons, and joint capsules, commonly known as mechanoreceptors. The muscle spindle, a crucial proprioceptor, is stretched during eccentric contraction of muscle, thus generating an action potential on afferent fibers to convey a proprioceptive information to the sensorimotor cortex in the brain. For exercise therapy in patients with locomotor disease, proprioception serves an essential function for motor control; thus, this should be considered to obtain effective muscle output. As postural control is achieved by proprioceptive function according to the balance between the lower limb and trunk, relative proprioceptive weighting ratio can help clarify proprioceptive control using muscle response to mechanical vibration. The absence of proprioceptive information congruent with motor intention activates cortical center monitoring incongruence of sensation, leading to pathological pain. Therapeutic procedures may aim to restore the integrity of cortical information processing in musculoskeletal chronic pain. Poor proprioception is one of the main causes of decreased postural balance control in elderly patients with low back pain (LBP). It has been hypothesized that proprioception of the lower limbs deteriorates with age-related muscle mass loss (sarcopenia), which increases the proprioceptive burden on the lumbar spine. Accurate diagnosis of the proprioceptive function is important for establishing a treatment procedure for proprioceptive recovery, and further prospective research is required to clarify the relationship between proprioception and LBP improvement.

Background: Considering the limitations of cell therapy, in case of adequate treatment efficacy, conditioned media (CM) may be a desirable alternative to cell therapy. Hence, the present systematic review and meta-analysis aims to evaluate the efficacy of mesenchymal stem cell-derived conditioned media (MSC-CM) in movement resolution following spinal cord injury (SCI) in animal models.

Methods: A comprehensive search in the databases of Medline, Scopus, Web of Science, and Embase was completed until the end of March 2021. Animal studies that evaluate the efficacy of MSC-CM on movement resolution following SCI were defined as the inclusion criteria. Lack of an SCI-untreated group, CM derived from a source other than MSC, not assessing motor function, failure to report CM administered dose, a follow-up period of less than 4 weeks, duplicates, and review articles were counted as the exclusion criteria. Final results are presented as overall standardized mean difference (SMD) with a 95% confidence interval (CI).

Results: From the 361 nonduplicate articles, data from 11 articles were entered into the present meta-analysis. The analyses showed that MSC-CM administration in SCI animal models promotes motor recovery (SMD=2.32; 95% CI: 1.55, 3.09; p<0.0001). Subgroup analysis was performed because of the noticeable heterogeneity between the studies (I²=80.97%, p<0.0001), depicting that antibiotic administration, delivery amount, delivery type, and follow-up time were the possible sources of heterogeneity. Moreover, multiple meta-regression demonstrated that in cases of delivery amount of more than 120 μL, the efficacy of MSC-CM administration in motor recovery is more than that of delivery amount of less than 120 μL (regression coefficient=3.30; 95% CI: 0.72, 5.89; p=0.019).

Conclusions: Based on the results of the present study, it can be concluded that MSC-CM administration in SCI models improves motor recovery. The efficacy of this treatment strategy significantly increases at doses higher than 120 μL.

Introduction: The alpha-defensin lateral flow test has been used in periprosthetic joint infection as a diagnostic support tool because of its simplicity and speed. However, the test has not been used to diagnose spinal infections. The purpose of this study was to investigate the efficacy of the alpha-defensin lateral flow test for diagnosing spinal infections.

Methods: The subjects were 11 patients who were suspected of having spinal infections from October 2019 to August 2021 and underwent biopsies at a single institution. There were nine male and two female patients, with an average age of 60.7 (14-87) years. For diagnosing infection, the patient's consent for biopsy was obtained, and the sample was collected by computed tomography-guided aspiration biopsy or open biopsy at the site considered to be a possible abscess. The samples were subjected to a bacterial culture test, an acid-fast bacillus culture test, and an alpha-defensin lateral flow test (Synovasure^® lateral flow test; Zimmer Biomet, IN, USA).

Results: Of the 11 suspected spinal infections, the alpha-defensin lateral flow test was positive in 8 cases, negative in 2 cases, and undeterminable in 1 case. Of the 10 cases excluding the undeterminable case, the definitive diagnosis was 9 cases of spinal infection (spondylitis: 6 cases, spinal implant infection: 3 cases) and 1 case of vertebral body fracture. The alpha-defensin lateral flow test demonstrated a sensitivity of 88.9%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 50%. The biopsy sample culture test demonstrated a sensitivity of 77.8%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 33.3%.

Conclusions: We suggested that the alpha-defensin lateral flow test might be useful as a diagnostic support tool for spinal infections.

Introduction: Reports of myelopathy with C7 anterior spondylolisthesis are extremely rare, and the surgical outcomes, clinical features, and their effects remain unknown. We describe six patients who underwent surgery for C7 spondylolisthesis with myelopathy.

Methods: Six patients who underwent operative treatment for C7 spondylolisthesis with myelopathy were retrospectively reviewed. C7 spondylolisthesis was defined as an anterior slippage of more than 2 mm on X-ray or computed tomography (CT). The images were evaluated using radiography, magnetic resonance imaging (MRI), and CT. Clinical outcomes were evaluated using the thoracic Japanese Orthopedic Association (T-JOA) score and Frankel grade.

Results: Facet joint arthrosis was observed in all patients at the C7/T1 level. MRI revealed a juxta-facet cyst in the spinal segment in three cases and a high signal change in four cases. We could visualize C7 anterior slippage from the lateral radiograph in one case. The mean time from onset to diagnosis was 95 (range, 7-280) months. Posterior spinal fusion using pedicle screws and interlaminectomy was performed in five cases. Cystectomy with partial laminectomy was performed in one case with a juxta-facet cyst. The mean JOA score was 6±0.7 preoperatively and improved to 9±1.5 at the final follow-up. The Frankel grades of all patients improved by more than one grade.

Conclusions: In this study, myelopathy with C7 spondylolisthesis was relatively severe, and we believe that the mechanical stress between the rigid thoracic vertebrae and the movable cervical spine may cause C7 spondylolisthesis. Posterior spinal fusion and partial laminectomy for C7 spondylolisthesis with myelopathy resulted in satisfactory outcomes.

Introduction: This prospective randomized controlled study aimed to examine the role of modest systemic hypothermia in individuals with acute cervical spinal cord injury (SCI) regarding neurological improvement. Studies have shown that the application of hypothermia is safe and that it improves neurological outcomes in patients with traumatic spine injury. Hypothermia helps in decreasing a secondary damage to the cord.

Methods: Twenty cases of acute post-traumatic cervical SCI with AISA were selected and randomly divided into two treatment groups: Group A-Hypothermia with surgical decompression and stabilization; and Group B-Normothermia with surgical decompression and stabilization. American Spinal Injury Association (ASIA) motor and sensory scores were evaluated at presentation; post-surgery; and at a 2-week, 6-week, and 12-week follow-up.

Results: At the final follow-up, the change in ASIA motor scores of Group A was 46 (11.5-70.5) and Group B 13 (4.5-58.0), whereas ASIA sensory scores were 118 (24.75-186.5) and 29 (15.25-124.0) in Group A and Group B, respectively. ASIA scores between the two groups were statistically significantly different at a 2-week follow-up (ASIA motor p=0.04, ASIA sensory p=0.006), showing early improvement in the hypothermia group. There was no significant difference between the two groups on further follow-up.

Conclusions: Hypothermia can be applied safely to subjects with acute SCI. Our study showed that hypothermia was beneficial in the early improvement of functional outcomes in acute cervical SCI.

Introduction: Laminoplasty is a well-established technique used to manage cervical myelopathy (CM). Nevertheless, the degree to which United States surgeons have adopted laminoplasty from Japan to treat CM is less clear. The purpose of this study was to compare operative management strategies for CM in the United States (US) with Japan.

Methods: This study used a retrospective cohort of 16,084 patients from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database and 389,872 patients from the Japanese Diagnosis Procedure Combination (DPC) database from 2007 to 2015. Patients with the following diagnoses were collected: spondylosis with myelopathy (ICD-19; 721.1, ICD-10; M47.12) and disk herniation with myelopathy (ICD-9; 722.71, ICD-10; M50.00). The proportion of surgeries between Japan and the US was compared using a linear regression model controlling for year.

Results: US surgeons utilized anterior procedures in 70% of cases compared to 9% in Japan (p<.001). In contrast, Japan had significantly more laminoplasties than the US (43% vs. 4%, respectively, p<.001). The percentage of laminoplasty in Japan (43%) relative to the percentage in the US (4%) was significantly different (p<.001). Accounting for increases in the number of total surgeries per year seen in the ACS-NSQIP and DPC databases, no specific surgery demonstrated a significant increase or decrease over the 8 years.

Conclusions: Japanese surgeons employ laminoplasty to treat CM approximately ten times more frequently than US surgeons who prefer anterior procedures.

Introduction: Massive hemothorax due to thoracic vertebral fractures (MHTVF) is a potentially lethal condition; however, its epidemiological and clinical data have been rarely described. Thus, in this study, we aimed to evaluate the incidence, predictive factors, and clinical features of MHTVF.

Methods: This retrospective cohort study enrolled 202 consecutive patients (136 male and 66 female patients) with thoracic vertebral fractures treated at our institute between January 2009 and December 2019. Their mean age was 60.7 (range, 17-90) years. Unstable fractures accounted for 57.4% (n=116) of the total fractures. The patients were then divided into MHTVF and non-MHTVF groups. We assessed the following MHTVF-associated factors: sex, age, history of medical conditions, anticoagulation/antiplatelet drug use, injury severity score, anatomical distribution of levels of the vertebral fractures, fracture type, and presence or absence of diffuse idiopathic skeletal hyperostosis (DISH) fracture.

Results: In total, eight patients (six men and two women) with a mean age of 68.9 years (range, 22-85 years) were determined to exhibit MHTVF. The incidence of MHTVF in patients with unstable thoracic spinal fractures was 6.9%, whereas none of those with stable spinal fractures exhibited MHTVF. Factors like type B (p=0.049) and DISH (p=0.017) fractures were noted to be significantly associated with the MHTVF. Three patients experienced shock upon arrival, whereas two exhibited delayed shock. Chest tube insertion and/or emergency thoracotomy was performed. The survival rate was 100.0%.

Conclusions: MHTVF is not rare. Because type B and DISH fractures are identified as predictive factors of MHTVF, it must be carefully treated to avoid preventable death even after hospitalization in patients with these thoracic fractures.

Introduction: Sacroiliac joint pain (SIJP) is one of the pathological conditions of adjacent segment disorders occurring after adult spinal deformity (ASD) surgery. This study aimed to test the hypothesis that even in ASD surgery using S2 alar-iliac (S2AI) screws, SIJP can develop much earlier than reported previously and can be rescued by ultrasound-guided sacroiliac joint block.

Methods: Overall, 94 patients with ASD treated with long spinal fusion using S2AI screws were prospectively investigated for SIJP postoperatively, and the effect of ultrasound-guided sacroiliac joint block was evaluated. Additionally, the relationship between the symptomatic side of the SIJP and the surgical procedure; the preoperative and postoperative whole-spine sagittal and coronal alignment, lumbar pelvis sagittal plane alignment, and pelvic incidence-lumbar lordosis were retrospectively compared between the groups with and without SIJP.

Results: Eleven of 94 cases (11.7%) developed SIJP. The average onset was 12.0 (±6.2) days after surgery. The "one-finger test," "Gaenslen test," and "tenderness of the posterosuperior iliac spine" had high positivity rates for SIJP. Night pain occurred in 81.8% of patients and was one of the diagnostic features. There were no significant relationships between the symptomatic side of SIJP and the approach-side of lumbar interbody fusion, donor site of the iliac bone graft, or malposition of the S2AI screw. There were no significant differences in preoperative characteristics and radiological parameters between the SIJP-positive and -negative groups preoperatively, postoperatively, or in postoperative changes. Two of the 11 cases required the SIJ block four times, but all patients eventually achieved >70% pain relief with no recurrence.

Conclusions: For good pain control and physical therapy, the fact that early buttock-groin pain after spinal fusion surgery has a 12% likelihood of being due to SIJP and can be relieved with the ultrasound-guided SIJ block is clinically important for diagnosis and pain management.

Introduction: Vertebral slip reduction has been recommended in arthrodesis for lumbar degenerative spondylolisthesis (LDS) to achieve balanced spinal alignment and bone fusion. However, what determines the degree of slip reduction using cortical bone trajectory technique for lumbar pedicle screw insertion is yet to be determined. Thus, in this study, we aim to investigate the slip reduction capacity using cortical bone trajectory (CBT) technique and to identify factors affecting the slip reduction rate.

Methods: This is a retrospective radiological evaluation of prospectively collected patients. In total, 49 consecutive patients who underwent single-level transforaminal lumbar interbody fusion for LDS using the CBT technique were included (mean follow-up: 28.9 months). Firstly, radiological parameters of fused segment including the percentage of anterior vertebral slip (%slip), lordotic angle, and disk height were measured. Then, patient and procedure-related parameters were examined to determine factors related to the slip reduction rate using multiple regression analysis.

Results: The %slip was reduced from 15.0±4.8 to 1.6±2.3% immediately after surgery and 2.2±2.9% at the last follow-up (p<0.01), with a slip reduction rate of 87.5±15.7% and correction loss of 0.6±2.1%. As per multivariate regression analysis, it was found that preoperative %slip (standardized regression coefficient [β]=−0.55, p=0.003) and the depth of screw insertion in the caudal vertebra (β=0.38, p=0.03) were significant independent factors affecting slip reduction rate (adjusted R²=0.29, p=0.008).

Conclusions: To the best of our knowledge, this study is the first to investigate the capacity for and factors affecting slip reduction using the CBT technique for LDS. The CBT technique may be a useful option for achieving slip reduction, and the depth of screw insertion in the caudal vertebra was identified as a significant technical factor to obtain a more significant reduction of slipped vertebra.

Introduction: Long-term clinical outcomes of microendoscopic laminotomy (MEL) for patients with multilevel radiographic lumbar spinal canal stenosis (LSS) have not been widely explored. The clinical significance and natural progression of additional untreated levels (e.g., remaining radiographic (RR) -LSS not addressed by selective MEL) remain unknown. This retrospective study aimed to investigate the long-term clinical outcomes of selective MEL in LSS patients and compare outcomes between patients with and without remaining RR-LSS to determine the efficacy of this procedure.

Methods: Forty-nine patients at a single center underwent posterior spinal microendoscopic decompression surgery for neurogenic claudication or radicular leg pain in moderate-to-severe spinal stenosis. The patients were categorized into the RR-LSS-positive and RR-LSS-negative cohorts based on unaddressed levels of stenosis. Pre-operative and 10-year follow-up evaluations, including the Japanese Orthopedic Association (JOA) score, visual analog scale (VAS) score for low back pain and leg pain, Oswestry Disability Index (ODI), and satisfaction, were compared between the groups. Additionally, the need for reoperation was determined.

Results: MEL significantly improved JOA scores, lumbar VAS, and ODI over the 10-year postoperative period. Pre-operative characteristics and postoperative outcomes were not significantly different between the cohorts. Overall, 18.4% (9/49) of patients required reoperation during the follow-up period. The reoperation rate in the RR-LSS-positive (13.8%; 4/29) group was similar to that in the RR-LL-negative (15.0%; 3/20) group.

Conclusions: MEL is effective for lumbar stenosis, with improved clinical outcomes up to 10 years following surgery. Selective MEL, addressing only symptomatic levels in multilevel stenosis, with residual remaining lumbar stenosis, is similarly effective without increased reoperation rates. Surgeons may consider more limited selective decompression in patients with multilevel stenosis, avoiding the risk and invasiveness of extensive procedures.

Level of Evidence: Level III.

Introduction: Proximal junctional failure (PJF) and rod fracture (RF) are the primary reasons for revision surgery after a long corrective fusion for the adult spinal deformity (ASD). However, many recent studies on ASD are multicenter studies from the US and European racial characteristics may differ from those of Asians. Therefore, the risk factors for revision surgery because of PJF and RF after ASD surgery were evaluated in Japanese patients.

Methods: Patients with ASD who underwent corrective surgery from the thoracic vertebrae to the ilium at the authors' institution were reviewed. Demographic, surgical, and radiographic parameters were included in the analysis. Univariate and multivariate regression models were used to analyze the risk factors for PJF and RF.

Results: Two hundred and fifty-nine patients were included in the study. A total of 73 patients (28.1%) required revision surgery because of mechanical complications and 15 patients (5.7%) required revision surgery because of PJF on average 380 days after surgery. In PJF cases, body mass index (BMI) and pelvic tilt were significantly higher (p=0.01, p=0.048, respectively). BMI was an independent risk factor for revision owing to PJF (odds ratio [OR], 1.16; p=0.013). A total of 49 patients (18.9%) required revision owing to RF on average 867 days after surgery. Three-column osteotomy (p<0.001), significant blood loss (p=0.048), number of fusion segments (p=0.023), absence of lateral lumbar interbody fusion (p<0.001), and sagittal imbalance (p=0.033) were risk factors for revision surgery owing to RF in the univariate analysis. Three-column osteotomy (OR 4.41; p<0.001) and number of fusion segments (OR 1.21; p<0.009) were independent factors for revision surgery owing to RF.

Conclusions: PJF occurred in a relatively early phase (approximately 1 year) after surgery in patients with ASD with high BMI. Conversely, RF occurred approximately 2.5 years after surgery in three-column osteotomy and spinal fusion cases that involvedlonger fusion range.

Introduction: In this study, it is aimed to compare the long-term results of patients with short-segment instrumentation where screws were inserted into the fractured vertebra with those of patients with long-segment instrumentation applied by skipping the fractured vertebra and reveal the predictive markers in decision-making for screwing fractured vertebra.

Methods: Patients were separated into two groups, namely, Group A (patients in which the fractured vertebra and vertebrae above and below the fractured vertebra were screwed (short-segment instrumentation, n=22) and Group B (patients in whom the fractured vertebra was not screwed, whereas two vertebrae above and below the fractured vertebra were screwed (long-segment instrumentation, n=27).

Results: The presence of pedicle fracture, AOSpine Classification Scale score, the height of the fractured vertebra, vertebra height below the fractured vertebra, spinal canal diameter, and duration of stay in hospital were different between the groups, preoperatively (p<0.05). Fractured vertebra height, vertebra height below the fractured vertebra, and Karnofsky Performance Scale score were different between the groups in long-term follow-up (p<0.05). The preoperative measurement values were similar to each group's postoperative long-term follow-up results. Logistic regression analysis revealed that the presence of pedicle fracture, AOSpine Classification Scale score, vertebra height below the fractured vertebra, and spinal canal diameter could be the best parameters in decision-making for screwing fractured vertebra (p<0.05).

Conclusions: Both instrumentation procedures were observed to have similar effectiveness in preventing a collapse in fractured vertebra during long-term follow-up. It was thought that the AOSpine Classification Scale score, presence of pedicle fracture, vertebra height below the fractured vertebra, and spinal canal diameter could be used as predictive markers in decision-making for screwing fractured vertebrae. Consequently, it was concluded that patients with pedicle fractures, more height loss in the vertebra below the fractured vertebra, and narrow spinal canal would not be suitable for screwing the fractured vertebra.

Introduction: This study aimed to investigate whether difficulties in some motions concomitant with increased spinal loads would distinguish between patients with and without fresh vertebral compression fractures (VCFs) in elderly patients with acute low back pain.

Methods: Of the 85 screened patients aged 65 years and older, 80 eligible participants were enrolled. Participants were asked about difficulties (none, slightly, and extreme) in getting up and rolling over and then divided into the VCF group or the non-VCF group after imaging examinations. A logistic regression model was used to determine whether the following variables were associated with the presence of fresh VCFs: age, sex, pain duration, pain severity, and difficulties in getting up and rolling over. Then, a multivariate stepwise logistic regression model was used to determine which variable correlated with the presence of fresh VCFs. Subsequently, we created a key symptom score for the presence of fresh VCFs, and discrimination of fresh VCFs was tested using the receiver operating characteristic (ROC) curve.

Results: In the multivariate logistic regression analysis, difficulties in getting up (p<0.05) and rolling over (p<0.01) were associated with VCFs after controlling for age, sex, and pain severity. As we weighted with 0, 1, or 2 to assess the severity of key symptoms, the score ranged from 0 to 4. The ROC curve showed that scoring of the two key symptoms significantly discriminated participants with or without VCFs with an area under curve=0.88 (p<0.001). A score of 2 on the key symptom score showed a sensitivity of 97%, and a score of 4 showed a specificity of 95% for fresh VCFs.

Conclusions: The results indicate that there may be specific symptoms in elderly patients with fresh VCFs. Scoring of the two key symptoms may be useful for screening fresh VCFs in this population.

Introduction: Corrective fusion for adult scoliosis often requires fusion from the thoracic spine to the lower lumbar spine or pelvis. However, it is often difficult to determine the lowest instrumented vertebrae (LIV), especially in younger patients. The purpose of this study was to summarize the clinical outcomes and revision surgery rates after corrective fusion for adult scoliosis at different LIV levels in patients under 50 years of age.

Methods: We retrospectively analyzed 25 patients with adult scoliosis (mean age, 38 years; mean follow-up, 65 months) who underwent corrective fusion from the thoracic spine to L4, L5, or pelvis between 2010 and 2018. Preoperative and at least 2 years' postoperative radiographic parameters, patient-reported outcomes (Scoliosis Research Society-22r [SRS-22r]), mechanical complications, and revision surgery were investigated, and comparisons were made between two groups: the L4 and L5 (L) group (n=14) and the pelvic group (n=11).

Results: Both groups showed a significant improvement in the SRS-22r domains of Self-image and Subtotal postoperatively compared with the baseline (P<0.05). The incidence of rod fracture was significantly higher in the pelvic group (5 patients, 45%) than in the L group (0 patients, 0%) (P=0.001). In addition, revision surgery was performed five times in 4 patients (36%) in the pelvic group compared with 0 in the L group (P=0.068).

Conclusions: In the L group, clinical outcomes improved in the medium term, with no patients requiring revision surgery. In the pelvic group, the rod fracture rate was higher, but the clinical outcomes improved.

Introduction: Although patients with diffuse idiopathic skeletal hyperostosis (DISH) do not have low bone density, it is a risk factor for spine fractures associated with DISH. We investigated the characteristics and bone metabolism markers of patients with DISH having low bone density to assess whether osteoporosis medication is necessary to prevent fractures.

Methods: A cross-sectional study was conducted between April 1, 2008, and March 31, 2019. The 86 patients included were divided into two groups according to their T-scores-one group had low bone density and DISH, and the other group did not. Group A (T-score≤−1) and B (T-score>−1) data were adjusted for confounding factors and compared for differences in age, body weight, maximum number of vertebral bodies with bony bridges between adjacent vertebrae (max VB), and previous history (hypertension, malignant tumors, diabetes mellitus, cardiac diseases, chronic renal failure, and spinal fractures). In Group A, multiple linear regression was used to investigate relationships among max VB, femur bone mineral density (BMD), total type I procollagen N-terminal propeptide (P1NP), and tartrate-resistant acid phosphatase 5b (TRACP-5b).

Results: Group A had 36, and Group B had 50 male patients with DISH. Patients in Group B were heavier than those in Group A. The mean femur BMD in Group A was age-appropriate, and that in Group B was higher than the age-appropriate femur BMD. The mean values of P1NP and TRACP-5b were within the normal range. Max VB was positively correlated with total P1NP in Group A. Total P1NP was significantly and positively correlated with TRACP-5b.

Conclusions: The DISH group with a T-score of ≤−1 was age-appropriate. The group with a T-score of >−1 had higher BMD because of their higher body weight. The group with a T-score of ≤−1 had good bone metabolism and did not require aggressive osteoporosis treatment.

Introduction: There are various surgical interventions to manage osteoporotic vertebral compression fracture. Modular spine block (MSB) is a novel intravertebral fixator that can be assembled. This study aimed to quantitatively investigate the force distribution in vertebrae with the various structural designs and implantation methods by finite element analysis (FEA).

Methods: A three-dimensional nonlinear FEA of the L3 implanted with MSB was constructed. Different structural designs (solid vs. hollow) and implantation methods (three-layered vs. six-layered and unilateral vs. bilateral) were studied. The model was preloaded to 150 N-m before the effects of flexion, extension, torsion, and lateral bending were analyzed at the controlled ranges of motion of 20°, 15°, 8°, and 20°, respectively. The resultant intervertebral range of motion (ROM) and disk stress as well as intravertebral force distribution were analyzed at the adjacent segments.

Results: The different layers of MSB provided similar stability at the adjacent segments regarding the intervertebral ROM and disk stress. Under stress tests, the force of the solid MSB was shown to be evenly distributed within the vertebrae. The maximum stress value of the unilaterally three-layered hollow MSB was generally lower than that of the bilaterally six-layered solid MSB.

Conclusions: The MSB has little stress shielding effect on the intervertebral ROM and creates no additional loading to the adjacent disks. The surgeon can choose the appropriate numbers of MSB to fix vertebrae without worrying about poly (methyl methacrylate) extravasation, implant failure, or adjacent segment disease.

Introduction: Lumbar spondylolysis is common in pediatric athletes, and many athletes can return to sports with conservative treatment. There are two initial treatment strategies: bony union or pain management, but the outcomes of these strategies have not been clarified. The purpose of this study is to investigate the rates of return to sports (RTS) and recurrence in pediatric athletes after conservative treatment for lumbar spondylolysis and to compare both treatment strategies.

Methods: A total of 180 patients with lumbar spondylolysis were managed with a trunk brace and cessation of sports activity (bone union [BU] group, n=95) or treated for pain only (pain management [PM] group, n=85). RTS and recurrence rates according to type of conservative treatment were compared.

Results: The RTS rate was 98.9% in the BU group and 97.6% in the PM group at 4.7±1.9 and 1.8±1.7 months, respectively. Recurrence occurred in 7.4% of patients in the BU group at 19.0±16.0 months and in 4.8% of the PM group at 17.8±5.2 months.

Conclusions: The RTS rate in pediatric athletes with lumbar spondylolysis was high at more than 95%, regardless of type of conservative treatment. The mean time to RTS was longer in the BU group than in the PM group (4.7 vs. 1.8 months) because of the time required for bone healing. There were several cases of recurrence after RTS. Strategies to prevent recurrence of lumbar spondylolysis in pediatric athletes are discussed.

Introduction: This study investigated brace-related stress, trunk appearance perception, and quality of life in adolescent girls with idiopathic scoliosis who wear the Milwaukee brace for treatment.

Methods: Fifty-two adolescent girls with idiopathic scoliosis participated in this study. They had been under treatment with Milwaukee brace for at least three months. They filled out four questionnaires, including the revised 22-item Scoliosis Research Society questionnaire (SRS-22r), the Brace Questionnaire (BrQ), the Bad Sobernheim Stress Questionnaire-Brace (BSSQ-Brace), and the Trunk Appearance Perception Scale (TAPS).

Results: Twenty participants had high stress levels, and thirty-two had moderate stress levels. The total score and emotional and social function scores of the BrQ were significantly higher in participants with high stress compared to those with moderate stress. There was no significant difference between the two groups in the SRS-22r and TAPS questionnaires scores. However, a high Cobb angle had significantly worsened their perception of trunk appearance.

Conclusions: It seems that among quality-of-life parameters, social and emotional functions are more affected by stress level in treating adolescent girls with idiopathic scoliosis with a brace. In addition, patients with high stress levels have a worse perception of their trunk appearance.

Introduction: Most sacroiliac joint (SIJ) disorders are conservatively treated; however, patients with severe pain occasionally require SIJ arthrodesis after failure of continuous conservative management for more than 6 months. We investigated the incidences of preoperative tenderness in the sacrotuberous ligament (STL) and postoperative lower-buttock pain originating from the STL to determine the best way to manage these symptoms to achieve good outcomes.

Methods: We retrospectively investigated 33 patients (14 men and 19 women) with a mean age of 47.7 years (range: 25-79 years) who underwent SIJ arthrodesis for severe pain confirmed using diagnostic SIJ injections between April 2009 and December 2019. We investigated the pain improvement at or around the posterior superior iliac spine (PSIS) pre- and postoperatively using the visual analogue scale (VAS) values, incidence of tenderness of the STL before surgery, rate of the persisting STL tenderness, incidence of new-onset STL pain, and treatment options for STL pain postoperatively.

Results: The mean VAS value at or around the PSIS was significantly relieved postoperatively from 85.6 to 31.5 mm (P<0.001). Preoperative tenderness of the STL was identified in 21 of 33 patients (63.6%). The STL tenderness resolved after surgery in 12 of these 21 patients (57.1%); however, it persisted in nine patients (42.9%), all of whom were women. Of the 12 patients who did not have preoperative STL tenderness, 4 (33.3%) developed lower-buttock pain and had STL tenderness. In total, 9 (27.3%) of the 33 patients whose progress could be followed up after SIJ arthrodesis had pain originating from the STL; the STL pain in 8 of the 9 patients was relieved after the STL injections and physical therapy.

Conclusions: The STL pain can occur pre- and postoperatively, and management of both persisting and new-onset STL pain after SIJ arthrodesis should be considered to achieve better outcomes.

Introduction: Sacroplasty is a minimally invasive treatment option for severe pain due to sacral insufficiency fracture. Cement leakage is a known risk of sacroplasty. Despite the elevated risk to the L5 nerve root and lumbosacral trunk from cement leakage anterior to the sacral ala, there are no reports regarding surgical management of this complication.

Technical Note: We describe an anterior retroperitoneal transpsoas approach to the sacral ala to remove cement leakage causing acute L5 radiculopathy in a 57-year-old gentleman who had undergone sacroplasty for sacral insufficiency fracture (Denis zone 1). The approach provides rapid and excellent visualization of the sacral ala without manipulation of the iliac vessels.

Conclusions: We recommend that surgery be considered in a timely fashion, to utilize neuromonitoring, and that surgeons be aware of the considerable variability of the neurologic structures that will be encountered, which is described in this technical note.