The lower Osteotomy Level is Associated With Decreased Revision Surgery Due to Mechanical Complications After Three-Column Osteotomy in Patients With Adult Spinal Deformity: A Multi-Institutional Retrospective Study.

STUDY DESIGN: A multi-institutional retrospective study. OBJECTIVES: To investigate risk factors of mechanical failure in three-column osteotomy (3COs) in patients with adult spinal deformity (ASD), focusing on the osteotomy level. METHODS: We retrospectively reviewed 111 patients with ASD who underwent 3COs with at least 2 years of follow-up. Radiographic parameters, clinical data on early and late postoperative complications were collected. Surgical outcomes were compared between the low-level osteotomy group and the high-level osteotomy group: osteotomy level of L3 or lower group (LO group, n = 60) and osteotomy of L2 or higher group (HO group, n = 51). RESULTS: Of the 111 patients, 25 needed revision surgery for mechanical complication (mechanical failure). A lower t-score (odds ratio [OR] .39 P = .002) and being in the HO group (OR 4.54, P = .03) were independently associated with mechanical failure. In the analysis divided by the osteotomy level (LO and HO), no difference in early complications or neurological complications was found between the two groups. The rates of overall mechanical complications, rod failure, and mechanical failure were significantly higher in the HO group than in the LO group. After propensity score matching, mechanical complications and failures were still significantly more observed in the HO group than in the LO group (P = .01 and .029, respectively). CONCLUSIONS: A lower t-score and osteotomy of L2 or higher were associated with increased risks of mechanical failure. Lower osteotomy was associated with better correction of sagittal balance and a lower rate of mechanical complications.

Effect of vitamin D deficiency on surgical outcomes of degenerative cervical myelopathy.

Background: Due to its association with bone metabolic status and muscle strength/mass, vitamin D deficiency has the potential to affect neurological symptom recovery after surgery for degenerative cervical myelopathy (DCM). However, few studies have investigated the effects of vitamin D deficiency (serum 25(OH)D <20 ng/mL) on surgical outcomes in DCM patients. Herein, we investigated the prevalence of vitamin D deficiency in patients with DCM, and determined whether vitamin D deficiency affects surgical outcomes for DCM. Methods: In this retrospective observational study we assessed the recovery rate 1 year after surgery in 91 patients diagnosed with DCM who underwent surgery. First, we analyzed the correlation between vitamin D levels and various background factors. Then, patients were divided into 2 groups according to vitamin D sufficiency, and univariate analysis was performed on vitamin D and surgical outcomes. Finally, Spearman correlation analyses were performed to identify factors correlated with recovery rate after surgery for DCM. Results: The average Japanese Orthopedic Association score for the assessment of cervical myelopathy (C-JOA score) improved postoperatively. Age was positively correlated with vitamin D levels, and parathyroid hormone levels were negatively correlated with vitamin D levels. Among the 91 patients, 79.1% of patients were diagnosed with vitamin D deficiency. No significant differences in recovery rate were found between the vitamin D-deficient and vitamin D-sufficient groups. Finally, the Spearman correlation analysis showed a positive correlation between the preoperative C-JOA motor dysfunction score in the lower extremities and the recovery rate, while age demonstrated a negative correlation with recovery rate. Conclusions: No association was found between vitamin D deficiency and clinical outcomes after surgery for DCM. The results of this study do not support the need to normalize vitamin D levels for achieving neurological improvements in patients with DCM.

Risk factors for recurrence and regrowth of spinal schwannoma.

BACKGROUND: Spinal schwannoma recurs after initial surgery at a rate of 4%-6%, with known risk factors including subtotal resection, multilevel involvement, large tumor size, and malignant histopathology. This study examined risk factors for schwannoma recurrence and residual tumor regrowth. METHODS: Sixty-five patients who underwent resection of spinal schwannoma in our department between July 2010 and December 2018 and were followed up for more than 1 year were retrospectively analyzed for age, sex, follow-up duration, imaging and surgical data, recurrence, reoperation, and Japanese Orthopaedic Association scores before and 1 year after surgery. Patients with postoperative recurrence or residual tumor regrowth of >10% at the final visit (R+ group) were compared with patients without recurrence or regrowth (R- group). Multivariate logistic regression analysis was performed to analyze concurrent effects of risk factors on recurrence and regrowth. RESULTS: The 65 patients (mean age 52.4 years at surgery) had schwannomas involving cervical (n = 14), thoracic (n = 25), and lumbar (n = 26) spinal levels. Mean follow-up duration was 58 months. Location was intradural in 65%, extradural in 17%, and both intradural and extradural in 18%. There were 4 recurrences (6.2%), and the mean interval between surgery and recurrence was 18.8 months. Seven patients (10.8%) experienced regrowth. Comparing group R+ (n = 11) and group R- (n = 54), univariate analysis showed significant differences in Sridhar tumor classification, giant tumor (Sridhar classification II, IVb, and V), left-right and cranial-caudal tumor size, largest diameter, operative time, blood loss, subtotal resection, reoperation, fusion surgery, and follow-up duration. Multivariate logistic regression analysis revealed giant tumor (Sridhar classification types II, IVb, and V) as an independent risk factor for recurrence and regrowth. CONCLUSIONS: This retrospective review of 65 consecutive patients with spinal schwannoma in a single institution demonstrated that 16.9% had recurrence or regrowth, demonstrating that this potential risk should be kept in mind.

Factors Associated With Nonunion After Cervical Fusion Surgery.

Background Bony fusion is a critical factor in the outcome of cervical spinal fusion surgery. While several factors have been proposed to affect bony fusion, their relative importance remains unclear. This study aimed to investigate the factors associated with bony fusion after cervical spinal fusion surgery. Methods We retrospectively evaluated the significance of the various factors on bone fusion after cervical fusion surgery. Then, multivariate logistic regression analyses were performed to determine the independent factors associated with bony fusion. A receiver operating characteristic (ROC) analysis was performed to evaluate the cutoff threshold. Results This study included a total of 52 patients with a mean age of 64 years. Among them, 28 (54%) were male, and 39 (75.0%) achieved bony fusion. The multivariate logistic regression analysis showed that preoperative intact parathyroid hormone (PTH) levels (odds ratio, 1.04; 95% confidence interval, 1.01-1.08; p-value = 0.02) and hemoglobin A1c (HbA1c) levels (odds ratio, 2.87; 95% confidence interval, 1.07-8.74; p-value = 0.04) were significant factors associated with bony fusion after cervical fusion surgery. The optimum cutoff values of intact PTH and HbA1c were 63.5 pg/mL and 6.2%, respectively. Conclusions This study identified preoperative intact PTH and HbA1c as significant factors associated with bony fusion after cervical fusion surgery. These biomarkers can be used to identify patients at higher risk of nonunion to optimize patient conditions and guide preoperative and postoperative management strategies.

Impact of body mass index on surgical outcomes and complications in adult spinal deformity.

BACKGROUND: Several studies have reported that overweightness and obesity are associated with higher complication rates in lumbar spine surgery. However, little is known about the effect of obesity on postoperative complications in adult spinal deformity (ASD) surgery, especially in the elderly. This study aimed to examine the effect of body mass index (BMI) on surgical outcomes and postoperative complications in elderly ASD patients undergoing surgical correction in Japan. METHODS: We conducted a retrospective, multicenter, observational study of 234 consecutive patients diagnosed with ASD who underwent corrective surgery. Patients were divided into two groups according to BMI, BMI <25 (153 patients, mean age 71.9 years) and BMI ≥ 25 (overweight/obese, 81 patients, mean age 73.3 years). Radiographic results and perioperative complications were compared between the two groups. RESULTS: Surgical complications occurred in approximately 20% of patients in each group; complications did not significantly differ between the two groups. A greater proportion of patients in the BMI ≥ 25 group experienced mechanical failure and DJK, although the difference was not significant. Preoperative mean lumbar lordosis (LL), pelvic incidence (PI) minus LL, sacral slope (SS) and sagittal vertical axis (SVA) were similar in the BMI < 25 and BMI ≥ 25 groups. However, the BMI ≥25 group had lower mean LL (p = 0.015) and higher PI minus LL (p = 0.09) postoperatively. The BMI ≥25 groups also had significantly smaller LL (p = 0.026), smaller SS (p = 0.049) and higher SVA (p = 0.041) at the final follow-up, compared to the BMI < 25 group. CONCLUSIONS: In the present study, no difference in medical or surgical complications after ASD surgery was found between overweight/obese patients (BMI ≥ 25) and those with BMI < 25. However, correction of LL and SVA was smaller in patients with overweight/obese patients.

Anterior Cervical Corpectomy with Fusion versus Anterior Hybrid Fusion Surgery for Patients with Severe Ossification of the Posterior Longitudinal Ligament Involving Three or More Levels: A Retrospective Comparative Study.

Various studies have found a high incidence of early graft dislodgement after multilevel corpectomy. Although a hybrid fusion technique was developed to resolve implant failure, the hybrid and conventional techniques have not been clearly compared in terms of perioperative complications in patients with severe ossification of the posterior longitudinal ligament (OPLL) involving three or more levels. The purpose of this study was to compare clinical and radiologic outcomes between anterior cervical corpectomy with fusion (ACCF) and anterior hybrid fusion for the treatment of multilevel cervical OPLL. We therefore retrospectively reviewed the clinical and radiologic data of 53 consecutive patients who underwent anterior fusion to treat cervical OPLL: 30 underwent ACCF and 23 underwent anterior hybrid fusion. All patients completed 2 years of follow-ups. Implant migration was defined as subsidence > 3 mm. There were no significant differences in demographics or clinical characteristics between the ACCF and hybrid groups. Early implant failure occurred significantly more frequently in the ACCF group (5 cases, 16.7%) compared with the hybrid group (0 cases, 0%). The fusion rate was 80% in the ACCF group and 100% in the hybrid group. Although both procedures can achieve satisfactory neurologic outcomes for multilevel OPLL patients, hybrid fusion likely provides better biomechanical stability than the conventional ACCF technique.

Comparison of Lateral Lumbar Interbody Fusion and Posterior Lumbar Interbody Fusion as Corrective Surgery for Patients with Adult Spinal Deformity-A Propensity Score Matching Analysis.

Lateral lumbar interbody fusion (LLIF) is increasingly performed as corrective surgery for patients with adult spinal deformity (ASD). This paper compares the surgical results of LLIF and conventional posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) in ASD using a propensity score matching analysis. We retrospectively reviewed patients with ASD who received LLIF and PLIF/TLIF, and investigated patients' backgrounds, radiographic parameters, and complications. The propensity scores were calculated from patients' characteristics, including radiographic parameters and preoperative comorbidities, and one-to-one matching was performed. Propensity score matching produced 21 matched pairs of patients who underwent LLIF and PLIF/TLIF. All radiographic parameters significantly improved in both groups at the final follow-up compared with those of the preoperative period. The comparison between both groups demonstrated no significant difference in terms of postoperative pelvic tilt, lumbar lordosis (LL), or pelvic incidence-LL at the final follow-up. However, the sagittal vertical axis tended to be smaller in the LLIF at the final follow-up. Overall, perioperative and late complications were comparable in both procedures. However, LLIF procedures demonstrated significantly less intraoperative blood loss and a smaller incidence of postoperative epidural hematoma compared with PLIF/TLIF procedures in patients with ASD.

Surgical stabilization of spinal metastasis in diffuse idiopathic skeletal hyperostosis ("Mets-on-DISH"): Two case reports.

RATIONALE: Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by ossification along the anterolateral aspect of at least 4 contiguous vertebral bodies. A fracture involving the fused vertebra in patients with DISH often leads to severe instability and spinal cord injury. Spinal metastasis (Mets) and DISH can coexist in elderly patients and increase their risk of pathologic vertebral fractures. However, there are few reports on concomitant spinal Mets and DISH. PATIENT CONCERNS: A 78-year-old man who complained of gradual onset of paraparesis, sensory loss below the umbilicus, and incontinence (case 1) and a 63-year-old woman who complained of severe back pain and urinary incontinence (case 2). DIAGNOSIS: Two patients were diagnosed with spinal Mets and DISH. INTERVENTIONS: Decompression surgery was performed at the metastatic sites in case 1 whereas instrumentation surgery was performed in case 2 despite the fracture having a benign appearance with no associated neurologic symptoms. OUTCOMES: A vertebral fracture developed at the metastatic vertebra after decompression surgery in case 1. Severe instability of the surgical site in this case resulted in persistent paralysis even after subsequent revision surgery with instrumentation. In contrast, the clinical course was benign without any neurologic dysfunction at the 2-year follow-up in case 2. LESSONS: Instrumentation surgery should be performed in patients with DISH who develop spinal Mets even if there is no apparent instability.

Identification of Predictive Factors for Mechanical Complications After Adult Spinal Deformity Surgery: A Multi-Institutional Retrospective Study.

STUDY DESIGN: A retrospective multicenter observational study. OBJECTIVE: To investigate correction surgeries that were performed in relatively aged patients in terms of mechanical complications (MCs) and their predictive factors. SUMMARY OF BACKGROUND DATA: The risk factors associated with MCs have not yet been well examined, especially in aged populations. METHODS: We retrospectively reviewed 230 surgically treated ASD patients with an average age of 72.2 years. Twenty-eight patients with ASD caused by vertebral fractures were excluded. The minimum follow-up was 2 years. Postoperative MCs were defined as proximal junction kyphosis, distal junction kyphosis, pseudoarthrosis, rod breakage, and vertebral fractures. We divided all the ASD patients into two groups: patients with MC (the MC (+) group) and patients without MC (the MC (-) group). Radiographic parameters were evaluated before and immediately after surgery. The SRS-Schwab ASD classification and global alignment and proportion (GAP) score were also evaluated. RESULTS: Of the 202 patients, 91 (45.0%) had MCs. The age at surgery was significantly higher in the MC (+) group than in the MC (-) group. Regarding radiographic parameters, postoperative global tilt (GT), pre- and postoperative thoracolumbar kyphosis (TLK), and postoperative thoracic kyphosis were significantly higher in the MC (+) group than in the MC (-) group. Other parameters, such as the proposed ideal alignment target of PI-LL<10, did not significantly affect MC rates. The GAP score was high in both groups and not significantly related to a higher rate of MC. Forward stepwise logistic regression indicated that the age at surgery, postoperative GT, and preoperative TLK were significant risk factors for MCs. CONCLUSION: Older age, higher postoperative GT, and higher pre and postoperative TLK can be risk factors for MCs. The GAP score was high in both groups and not significantly related to a higher rate of MC. LEVEL OF EVIDENCE: 4.

Is Modified K-line a Powerful Tool of Surgical Decision Making for Patients With Cervical Spondylotic Myelopathy?

STUDY DESIGN: Prospective observational single-center study. OBJECTIVE: To evaluate anterior decompression and fusion (ADF) or posterior surgery (PS) for patients with cervical spondylotic myelopathy (CSM) using the modified K-line (mK-line) and to compare clinical and radiologic outcomes between these 2 techniques. SUMMARY OF BACKGROUND DATA: The authors have previously reported that insufficient posterior decompression is often seen after laminoplasty for CSM in patients with preoperative anterior clearance of the spinal cord <4 mm on the basis of the mK-line. However, to our knowledge, no study has investigated the role, if any, of the mK-line in surgical decision making for patients with CSM. METHODS: A total of 87 patients were enrolled who underwent surgery for treatment of CSM between 2011 and 2015 at our hospital and who could be followed up for at least 2 years. ADF was selected as a more favorable procedure than PS in patients with anterior spinal clearance of <4 mm on preoperative midsagittal magnetic resonance imaging. On the basis of the Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy, the rate of recovery of the JOA scores at 2 years after surgery was investigated as a clinical outcome to compare these 2 groups. RESULTS: Mean age was 65.1 (±12.9) years in the ADF group (n=26) and 70.5 (±8.6) years in the PS group (n=61). In the PS group, 10 patients underwent posterior decompression with fusion. Mean preoperative and postoperative JOA scores were 10.5 and 14.1 points in the ADF group and 9.8 and 13.1 points in the PS group, respectively, showing no significant difference in recovery rate of JOA score between the ADF (58.9%) and PS (47.1%) groups. However, patients with a minimum interval between the mK-line and the anterior compression factor on the midsagittal image (minimum interval of the spinal cord) <4 mm tended to have unsatisfactory outcomes (recovery rate 29.6%) compared with patients with minimum interval of the spinal cord >4 mm (53.6%, P=0.07) in the PS group. CONCLUSION: Preoperative intervention using the mK-line is useful to predict residual cord compression and might homogenize postoperative clinical outcomes in both anterior surgery and PS.