Mid-Term Results of Single-Level Posterior Lumbar Interbody Fusion in Patients with Pelvic Incidence Minus Lumbar Lordosis Mismatch.

BACKGROUND: Recent literature suggests that sagittal imbalance is a risk factor for adjacent segment disease following fusion surgery. This study explored the influence of pelvic incidence minus lumbar lordosis (PI-LL) mismatch on the mid-term results and reoperation rate after single-level posterior lumbar interbody fusion (PLIF). METHODS: The participants of this study included 253 patients (80 men and 173 women; mean age 68.2 years) who underwent L4-5 single-segment PLIF. Preoperative PI-LL mismatch was defined as a PI-LL of 30° or greater. The patients were divided into 2 groups according to the presence or absence of PI-LL mismatch (PI-LL mismatch group; group M, Control group; group C), and the clinical outcomes and radiographic parameters were compared. RESULTS: Of the 253 cases, 25 were classified in group M and 228 in group C. The Japanese Orthopaedic Association score at 5 years postoperatively was 23.0 ± 3.6 in group M and 23.5 ± 5.1 in group C, and the recovery rate was 66.2 ± 32.6% in group M and 64.6 ± 21.4% in group C and there was no significant difference in the recovery rate between the 2 groups. All radiographic parameters except sacral slope were significantly worse in group M. One patient (4.3%) in Group M and 18 patients (7.8%) in Group C required revision surgery at 2.4 years (range 0.0-5.0) and there was no significant difference in the revision rate between the 2 groups. CONCLUSIONS: The mid-term results of L4-5 single-level PLIF were compared with and without PI-LL mismatch, with the threshold defined as 30°; however, there were no significant differences in both the Japanese Orthopaedic Association recovery and reoperation rates between the 2 groups.

Development of patient-reported outcome for adult spinal deformity: validation study.

Adult spinal deformity (ASD) is a complex condition that combines scoliosis, kyphosis, pain, and postoperative range of motion limitation. The lack of a scale that can successfully capture this complex condition is a clinical challenge. We aimed to develop a disease-specific scale for ASD. The study included 106 patients (mean age; 68 years, 89 women) with ASD. We selected 29 questions that could be useful in assessing ASD and asked the patients to answer them. The factor analysis found two factors: the main symptom and the collateral symptom. The main symptom consisted of 10 questions and assessed activity of daily living (ADL), pain, and appearance. The collateral symptom consisted of five questions to assess ADL due to range of motion limitation. Cronbach's alpha was 0.90 and 0.84, respectively. The Spearman's correlation coefficient between the change of main symptom and satisfaction was 0.48 (p < 0.001). The effect size of Cohen's d for comparison between preoperative and postoperative scores was 1.09 in the main symptom and 0.65 in the collateral symptom. In conclusion, we have developed a validated disease-specific scale for ASD that can simultaneously evaluate the benefits and limitations of ASD surgery with enough responsiveness in clinical practice.

Long-term outcomes of spine surgery in dialysis patients, focusing on activities of daily living, life expectancy, and the risk factors for postoperative mortality.

BACKGROUND: Because of the high incidence of major perioperative adverse events, spine surgery in dialysis patients should be recommended carefully after consideration of its risks and benefits. However, the benefits of spine surgery in dialysis patients remain unclear because of the lack of long-term outcomes. The purpose of this study is to elucidate the long-term outcomes of spine surgery in dialysis patients, focusing on activities of daily living (ADLs), life expectancy, and risk factors for postoperative mortality. METHODS: Data for 65 dialysis patients who underwent spine surgery at our institution and were followed up for a mean duration of 6.2 years were retrospectively reviewed. ADLs, number of surgeries, and survival times were recorded. The postoperative survival rate was calculated using the Kaplan-Meier method, and risk factors for postoperative mortality were investigated using a generalized Wilcoxon test and multivariate Cox proportional-hazards model. RESULTS: Compared with preoperative ADLs, ADLs significantly improved at discharge after surgery and at the final follow-up. However, 16 of the 65 patients (24.6%) underwent multiple surgeries, and 34 (52.3%) died during the follow-up period. Kaplan-Meier analysis revealed that the survival rate after spine surgery was 95.4% at 1 year, 86.2% at 3 years, 69.6% at 5 years, 59.7% at 7 years, and 28.7% at 10 years, and the overall median survival time was 99 months. Multivariate Cox regression analysis showed that a dialysis period of ≥10 years was a significant risk factor. CONCLUSIONS: Spine surgery in dialysis patients improved and maintained ADLs in the long term and did not shorten life expectancy. However, dialysis patients undergoing spine surgery require multiple surgeries more frequently, and a dialysis period of ≥10 years is a significant risk factor for postoperative mortality.

Spinopelvic sagittal realignment and incidence of adjacent segment disease after single-segment posterior lumbar inter-body fusion using 12° lordotic cages-a 2-year prospective cohort study.

Background: The importance of spinopelvic sagittal alignment for adjacent segment disease (ASD) after lumbar fusion surgery has been reported. However, no longitudinal cohort studies have determined the extent to which segmental alignment and spinopelvic global alignment can be achieved using 12° lordotic cages in posterior lumbar inter-body fusion (PLIF) and the extent to which the development of ASD can be prevented. The purpose of this study was to analyze changes in segmental and spinopelvic sagittal alignment after single-segment PLIF with 12° lordotic cages, to clarify the relationship between changes in segmental and spinopelvic sagittal alignment, and to report the incidence of ASD at 2 years postoperatively. Methods: Subjects in this 2-year prospective longitudinal cohort study were 28 patients who had undergone L4/5 PLIF using 12° lordotic cages. Incidence of operative ASD (O-ASD) was evaluated as clinical outcomes. Radiological measurements were examined preoperatively and at 3 months, 1 year and 2 years postoperatively. The following radiographic spinopelvic parameters were measured: segmental lordosis (SL) at L4/5; sagittal vertical axis (SVA); T1 pelvic angle (TPA); thoracic kyphosis (TK); lumbar lordosis (LL); sacral slope (SS); pelvic tilt (PT); and pelvic incidence (PI). With respect to radiological outcomes, changes in SL (ΔSL) and spinopelvic parameters and the incidence of radiological ASD (R-ASD) were evaluated. Correlations of ΔSL and changes in other spinopelvic parameters (ΔSVA, ΔTPA, ΔTK, ΔLL, ΔSS, ΔPT, and ΔPI-LL) between preoperatively and 3 months postoperatively were examined. Results: The follow-up rate was 100% (n=28) at 1 year postoperatively and 96.4% (n=27) at 2 years postoperatively. No cases of O-ASD were seen during 2 years of follow-up. Significant realignment was observed and maintained at 2 years postoperatively in almost all spinopelvic sagittal parameters (SL, SVA, TPA, LL, PT, PI-LL). Regarding the correlation between ΔSL and other parameters, significant correlations were detected with ΔSVA (r=-0.37, P<0.05) and ΔLL (r=0.538, P<0.01). Three cases (11.1%) showed R-ASD at 2 years postoperatively. Conclusions: PLIF with 12° lordotic cages for L4 degenerative spondylolisthesis improved SL and global sagittal realignment, and achieved satisfactory clinical outcomes with a low incidence of ASD during 2 years of follow-up.

Preoperative Pelvic Incidence Minus Lumbar Lordosis Mismatch in Repeat Posterior Lumbar Interbody Fusion Induces Subsequent Corrective Long Fusion.

OBJECTIVE: Only a few studies have addressed clinical outcomes of revision surgery for adjacent segment disease. The purpose of this study was to elucidate clinical outcomes of second (repeat) posterior lumbar interbody fusion (PLIF) by focusing on the relationship between clinical outcomes and spinopelvic parameters and predisposing factors requiring subsequent corrective long fusion after repeat PLIF. METHODS: We analyzed the data of 47 patients ≥40 years old who underwent repeat PLIF after single-segment PLIF owing to adjacent segment disease. The correlation between clinical outcomes and radiographic parameters was investigated. Patient demographics and radiographic parameters were compared between patients with and without subsequent corrective long fusion. RESULTS: Japanese Orthopaedic Association score at final follow-up was 13.4, and the recovery rate was 37.2%. All sagittal parameters except pelvic tilt and C7-central sacral vertical line at final follow-up showed weak to moderate (|r| = 0.30-0.56) correlation with clinical scores. Finally, 11% of patients required subsequent long corrective fusion. Pelvic incidence minus lumbar lordosis (PI-LL) mismatch (cutoff value of 27.5°) and thoracic kyphosis (cutoff value of 12.5°) before repeat PLIF were identified as predisposing factors for subsequent long corrective fusion. CONCLUSIONS: The clinical outcomes of repeat PLIF were inferior to outcomes of primary PLIF. Once PI-LL mismatch occurs after initial PLIF, it will be difficult to resolve the PI-LL mismatch during the second PLIF. To stop the chain of reoperations in patients whose preoperative PI-LL exceeds 27.5° before repeat PLIF, corrective long fusion may be a surgical option to consider.

Effect of segmental lordosis on early-onset adjacent-segment disease after posterior lumbar interbody fusion.

OBJECTIVE: Although several reports have described adjacent-segment disease (ASD) after posterior lumbar interbody fusion (PLIF), there have been only a few reports focusing on early-onset ASD occurring within 3 years after primary PLIF. The purpose of this study was to investigate the prevalence and postoperative pathologies of early-onset ASD and its relation with radiological parameters such as segmental lordosis (SL). METHODS: The authors reviewed a total of 256 patients who underwent single-segment PLIF at L4-5 for degenerative lumbar spondylolisthesis (DLS) and were followed up for at least 5 years. The definition of ASD was a symptomatic condition requiring an additional operation at the adjacent fusion segment in patients who had undergone PLIF. ASD occurring within 3 years after primary PLIF was categorized as early-onset ASD. As a control group, 54 age- and sex-matched patients who had not suffered from ASD for more than 10 years were selected from this series. RESULTS: There were 42 patients with ASD at the final follow-up. ASD prevalence rates at 3, 5, and 10 years postoperatively and at the final follow-up were 5.0%, 8.2%, 14.1%, and 16.4%, respectively. With respect to ASD pathologies, lumbar disc herniation (LDH) was significantly more common in early-onset ASD, while lumbar spinal stenosis and DLS occurred more frequently in late-onset ASD. Significant differences were detected in the overall postoperative range of motion (ROM) and in the changes in ROM (ΔROM) at L3-4 (the cranial adjacent fusion segment) and changes in SL (ΔSL) at L4-5 (the fused segment), while there were no significant differences in other pre- and postoperative parameters. In stepwise logistic regression analysis, ΔSL was identified as an independent variable (p = 0.008) that demonstrated significant differences, especially in early-onset ASD (control 1.1° vs overall ASD -2.4°, p = 0.002; control 1.1° vs early-onset ASD -6.6°, p = 0.00004). CONCLUSIONS: The study results indicated that LDH was significantly more common as a pathology in early-onset ASD and that ΔSL was a major risk factor for ASD, especially early-onset ASD.

Comparing Investigation Between Bilateral Partial Laminectomy and Posterior Lumbar Interbody Fusion for Mild Degenerative Spondylolisthesis.

STUDY DESIGN: A retrospective comparative study. OBJECTIVE: The present study aims to compare the surgical outcomes between bilateral partial laminectomy (BPL) and posterior lumbar interbody fusion (PLIF) in patients with mild degree of slippage. SUMMARY OF BACKGROUND DATA: To date, there have not been established surgical procedures for patients with mild degree of slippage. Moreover, sufficient studies that have compared surgical outcomes between BPL and PLIF are very few. MATERIALS AND METHODS: In this retrospective study, the authors enrolled 202 consecutive patients with degenerative spondylolisthesis with slippage at L3 or L4 of >3% who underwent spine surgery between 2005 and 2015. Patients were grouped into those who underwent single-segment PLIF (n=106) and those who underwent BPL (n=51). To adjust for potential confounders, the inverse probability of treatment weighting based on the propensity score was used. Surgical outcomes were compared between the BPL and PLIF groups. The threshold age for the final recovery rate of >70% was evaluated using receiver operating characteristic curve analyses to assess the limit of age to achieve good outcomes. Patients who underwent reoperation in both groups were also evaluated. RESULTS: Operation time and blood loss were significantly lower in the BPL group. The final recovery rate was similar between the groups without age stratification. The cutoff age to achieve a final recovery rate of >70% was 75 years in the PLIF group, and the final recovery rate was significantly higher in the PLIF group than in the BPL group in patients aged less than 75 years but not in patients aged 75 years or older. In addition, the reoperation rate was similar between groups, and all reoperations in the PLIF group were for adjacent segment disease. CONCLUSIONS: BPL is one of the useful options in patients with mild degenerative spondylolisthesis, particularly in patients aged more than 75 years.

A Detailed Clinical Course Leading to Hypoxic Ischemic Encephalopathy After Anterior Cervical Spine Surgery: A Case Report.

CASE: A 48-year-old woman underwent anterior cervical discectomy and fusion at C5/6. Extubation was performed immediately after surgery. Tachycardia, limb tremor, and panic attack developed approximately 4 hours after surgery at 16:15. Thirty minutes later, cessation of respiration occurred at 16:50. An experienced anesthesiologist attempted intubation but was unsuccessful because of laryngopharyngeal edema at the C2 level. Finally, an otolaryngologist performed tracheotomy and secured the airway at 17:20 but hypoxic encephalopathy ensued. CONCLUSION: Predicting the airway obstruction caused by laryngopharyngeal edema was very difficult; hence, to prevent critical complications, systematic perioperative management is essential in anterior cervical spine surgery.

Anterior selective stabilization combined with laminoplasty for cervical myelopathy due to massive ossification of the posterior longitudinal ligament: report of early outcomes in 14 patients.

OBJECTIVE: Surgical management of massive ossification of the posterior longitudinal ligament (OPLL) is challenging. To reduce surgical complications, the authors have performed anterior selective stabilization combined with laminoplasty (antSS+LP) for massive OPLL since 2012. This study aimed to elucidate the short-term outcome of the antSS+LP procedure. METHODS: The authors' analysis was based on data from 14 patients who underwent antSS+LP for cervical myelopathy caused by massive OPLL and were followed up for at least 2 years after surgery (mean follow-up duration 3.3 years). Clinical outcome was evaluated preoperatively, at 6 months and 1 year postoperatively, and at the final follow-up using the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy and the recovery rate of the JOA score. The following radiographic parameters were measured preoperatively, immediately after surgery, at 1 year after surgery, and at the final follow-up: the C2-7 angle, measured on lateral plain radiographs, and the segmental lordosis angle (SLA), measured on sagittal CT scans. The correlation between radiographic parameters and clinical outcomes was evaluated. RESULTS: The mean JOA score increased from 10.4 before surgery to 13.6 and 13.8 at 6 months and 1 year after surgery, respectively; at the final follow-up the mean score was 13.4. This postoperative recovery was significant (p = 0.004) and was maintained until the final follow-up. No patient required revision surgery due to postoperative neurological deterioration. However, the C2-7 angle gradually deteriorated postoperatively. Similarly, the SLA was significantly increased immediately after surgery, but the improvement was not maintained. The recovery rate at the final follow-up correlated positively with the change in C2-7 angle (r = 0.60, p = 0.03) and the change in SLA (r = 0.72, p < 0.01). CONCLUSIONS: AntSS+LP is safe and effective and may be an alternative to anterior decompression and fusion for the treatment of patients with massive OPLL. No postoperative neurological complications or significant postoperative exacerbation of neck pain were observed in our case series. Not only reducing intervertebral motion and decompressing the canal at the maximal compression level but also acquiring segmental lordosis at the maximal compression level are crucial factors for achieving successful outcomes of antSS+LP.

Effects of Concomitant Decompression Adjacent to a Posterior Lumbar Interbody Fusion Segment on Clinical and Radiologic Outcomes: Comparative Analysis 5 Years After Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To examine the effects of concomitant decompression adjacent to the posterior lumbar interbody fusion (PLIF) segment on the clinical and radiological outcomes 5 years after surgery. METHODS: Forty-five consecutive patients who had undergone L3/4 decompression with L4/5 PLIF for multilevel stenosis with degenerative spondylolisthesis (DS), and were followed for 5 years, were enrolled (group D). As a control group, 45 age-, sex- and preoperative disc height at L3/4-matched patients who had undergone L4/5 PLIF alone for L4/5DS were randomly selected (group A). Disc height, vertebral slippage, range of motion, posterior opening angle, segmental lordotic angle, presence of the intradiscal vacuum phenomenon (IVP) at the L3/4 level were measured on radiographs. Japanese Orthopaedic Association (JOA) score and the requirement for additional L3/4 surgery were evaluated. RESULTS: In terms of pre-/postoperative radiographic changes between the groups, significant differences were detected regarding disc height narrowing of ≥3 mm (group D 31%, group A 9%) and IVP (group D 33%, group A 11%). There were no significant differences in other radiological parameters. The recovery rate of the JOA score (group D 58%, group A 61%) and reoperation rate (group D 2.2%, group A 6.7%) were not significantly different between the groups. CONCLUSION: Concomitant decompression adjacent to the PLIF segment accelerated adjacent disc degeneration compared to PLIF alone, but it did not predispose to the development of instability 5 years after surgery. Moreover, the JOA score and reoperation rate were not significantly different between groups D and A.

Effect of segmental lordosis on the clinical outcomes of 2-level posterior lumbar interbody fusion for 2-level degenerative lumbar spondylolisthesis.

OBJECTIVE: Although the importance of spinopelvic sagittal balance and its implications for clinical outcomes of spinal fusion surgery have been described, to the authors' knowledge there have been no reports of the relationship between spinopelvic alignment and clinical outcomes for 2-level posterior lumbar interbody fusion (PLIF). The purpose of this study was to elucidate the relationship between clinical outcomes and spinopelvic sagittal parameters after 2-level PLIF for 2-level degenerative spondylolisthesis (DS). METHODS: This study was limited to patients who were treated with 2-level PLIF for 2-level DS at L3-4-5. Between 2005 and 2014, 33 patients who could be followed up for at least 2 years were included in this study. The average age at the time of surgery was 72 years, and the average follow-up period was 5.6 years. Based on clinical assessments, the Japanese Orthopaedic Association (JOA) score and recovery rate were evaluated. The patients were divided into 2 groups based on the recovery rate: the good outcome group (G group; n = 19), with recovery rate ≥ 50%, and the poor outcome group (P group; n = 14) with recovery rate < 50%. Spinopelvic parameters were measured using lateral standing radiographs of the whole spine as follows: sagittal vertical axis (SVA), thoracic kyphosis (TK), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), and segmental lordosis (SL) at L3-4-5. The clinical outcomes and radiological parameters were assessed preoperatively and at the final follow-up. Radiological parameters were compared between the 2 groups. RESULTS: The mean JOA score improved significantly in all patients from 10.8 points before surgery to 19.6 points at the latest follow-up (mean recovery rate 47.7%). For radiological outcomes, no difference was observed from preoperative assessment to final follow-up in any of the spinopelvic parameters except SVA. Although no significant difference between the 2 groups was detected in any of the spinopelvic parameters, there were significant differences in the change in SL and LL (ΔSL 3.7° vs -2.1° and ΔLL 1.2° vs -5.6° for the G and P groups, respectively). In addition, the number of patients in the G group was significantly larger for the patients with ΔSL-plus than those with ΔSL-minus (p = 0.008). CONCLUSIONS: The clinical outcomes of 2-level PLIF for 2-level DS limited at L3-4-5 appeared to be satisfactory. The results indicate that acquisition of increased SL in surgery might lead to better clinical outcomes.

Multiple-Repeated Adjacent Segment Disease After Posterior Lumbar Interbody Fusion.

BACKGROUND: Although posterior lumbar interbody fusion (PLIF) has provided satisfactory clinical outcomes, adjacent segment disease (ASD) is one of the most important complications affecting long-term results. However, according to ASD studies, few have described repeat surgery. The purpose of this study was to elucidate incidence, time period, and clinical features of multiple-repeated ASD after PLIF. METHODS: Subjects comprised 1112 consecutive patients (502 men, 610 women) who underwent 1-level PLIF for degenerative lumbar diseases. The mean age of patients was 66 years (range, 15-89). The mean follow-up period was 6.4 years (range, 0.5-21.1). The incidence and the time period of multiple-repeated ASD were investigated. To elucidate clinical features of the multiple-repeated ASD, all 4 cases were shown as the case description including radiographic parameters. RESULTS: Four (0.4%) developed multiple-repeated ASD: 3 women and 1 man. Primary PLIF was performed at L3-4 in 1 patient and at L4-5 in 3 patients. Two patients underwent adjacent segment decompression simultaneously. All patients required at least 3 additional surgeries due to newly occurred ASD after each PLIF. All patients developed iatrogenic flatback as ASD was repeated. As a result, corrective surgeries were required (thoracolumbar, 2; spinopelvic, 2). CONCLUSIONS: Multiple-repeated ASD was observed in 0.4% of the patients. All patients developed iatrogenic flatback as a result of repeated ASD, and corrective surgeries were required for these patients.

Adjacent Segment Disease After Posterior Lumbar Interbody Fusion: A Case Series of 1000 Patients.

STUDY DESIGN: Retrospective study. OBJECTIVE: There have been few reports of adjacent segment disease (ASD) after posterior lumbar interbody fusion (PLIF) with large numbers and long follow-up. The purpose of this study was to investigate (1) ASD incidence and time periods after primary PLIF, (2) repeat ASD incidence and time periods, and (3) ASD incidence and time periods by fusion length, age, and preoperative pathologies. METHODS: A total of 1000 patients (average age 67 years, average follow-up 8.3 years) who underwent PLIF for degenerative lumbar disorders were reviewed. ASD was defined as a symptomatic condition in which revision surgery was required. RESULTS: The overall ASD rate was 9.0%, and the average ASD period was 4.7 years after primary surgery. With respect to clinical features of ASD, degenerative spondylolisthesis at the cranial fusion segment was the most frequent. In terms of repeat ASD, second and third ASD incidences were 1.1% and 0.4%, respectively. As for ASD by fusion length, age, and preoperative pathologies, ASD incidence was increased by fusion length, while the time period to ASD was significantly shorter in elderly patients and those with degenerative lumbar scoliosis. CONCLUSIONS: In the present study, the overall ASD incidence was 9.0%, and the average ASD period was 4.7 years after primary operation. Second and third ASD incidences were 1.1% and 0.4%, respectively. Fusion length affected the ASD incidence, while aging factor and preoperative pathology affected the ASD time period.

Surgical Outcomes and Limitations of Decompression Surgery for Degenerative Spondylolisthesis.

STUDY DESIGN: A retrospective study. OBJECTIVES: To investigate surgical outcomes and limitations of decompression surgery for degenerative spondylolisthesis. METHODS: One hundred patients with degenerative spondylolisthesis who underwent decompression surgery alone were included in this study. The average follow-up period was 3.7 years. Radiography and magnetic resonance imaging were used for radiological assessment. Patients with a recovery rate of >50% throughout the study period were classified as the control group (Group C), while those with a recovery rate of <50% throughout the study period were classified as the poor group (Group P). Patients that had improved symptoms, and yet later showed neurological deterioration due to foraminal stenosis at the same level were classified as the exiting nerve root radiculopathy group (Group E), while those who showed deterioration due to slip progression at the same level were classified as the traversing nerve root radiculopathy group (Group T). RESULTS: Patient distribution in each group was 73, 12, 7, and 8 in Groups C, P, E, and T, respectively. As for preoperative radiological features, slippage and an upper migrated disc in Group P, disc wedging and an upper migrated disc in Group E, and lamina inclination and posterior opening in Group T were evident. The cutoff value of preoperative slippage with a poor outcome was 13%. CONCLUSIONS: Surgical outcomes of decompression surgery for degenerative spondylolisthesis were successful in 73% cases. Preoperative radiological features for poor outcomes were slippage of more than 13%, an upper migrated disc, disc wedging, and lamina inclination.

Controllable Risk Factors for Neurologic Complications in Posterior Lumbar Interbody Fusion as Revision Surgery.

BACKGROUND: The main concern with revision lumbar surgery is the possibility of neurologic complications. This retrospective study was conducted to clarify the risk factors, especially the effects of nerve stretching, for postoperative neurologic complications in posterior lumbar interbody fusion (PLIF) without excessive nerve retraction by bilateral total facetectomy as revision surgery. METHODS: Between 2005 and 2015, 50 consecutive patients underwent revision PLIF for recurrent stenosis or recurrent disc herniation. The patients were divided into two groups: patients with neurological complications (NC group) and patients without neurological complications (non-NC group). Radiological examinations to evaluate the magnitude of nerve stretching included the following pre- and postoperative plain radiograph measurements: anterolisthesis at flexion, intervertebral lordosis in the neutral position, and posterior disc height in the neutral position. RESULTS: Sixteen patients (32%) had neurological complications. The decrease in intervertebral lordosis was significantly greater in the NC group than that in the non-NC group (0.8° vs. -1.5°, P<0.05). Distraction of the posterior disc height was significantly greater in the NC group than that in the non-NC group (5.0 mm vs. 2.6 mm, P < 0.01). Neurological complications were seen in all patients with a decrease in intervertebral lordosis >3° and distraction of the posterior disc height >3 mm. CONCLUSIONS: Decreased intervertebral lordosis, and distraction of the posterior disc height, which can be controlled by surgeons, appear to be risk factors for neurological complications following revision PLIF. In revision PLIF, surgeons should create segmental lordosis without excessive disc height distraction.

Adjacent Segment Disease After Single Segment Posterior Lumbar Interbody Fusion for Degenerative Spondylolisthesis: Minimum 10 Years Follow-up.

STUDY DESIGN: A retrospective study. OBJECTIVE: The aim of this study was to investigate the incidence of adjacent segment disease (ASD) at 2, 5, and 10 years after primary posterior lumbar interbody fusion (PLIF), and clinical features of ASD. SUMMARY OF BACKGROUND DATA: Few reports have examined ASD after PLIF with more than 10 years of follow-up. Furthermore, no reports have examined limited conditions of preoperative pathology, fusion segment, and fusion method with long follow-up. METHODS: Data were reviewed for 128 patients who underwent single-segment PLIF for L4 degenerative spondylolisthesis and could be followed for at least 10 years. Mean age at the time of surgery was 63 years, and mean follow-up was 12.4 years. Follow-up rate was 62.4%. ASD was defined as radiological ASD (R-ASD), radiological degeneration adjacent to the fusion segment by plain X-rays and magnetic resonance imaging (MRI); symptomatic ASD (S-ASD), a symptomatic condition due to neurological deterioration at the adjacent segment degeneration; and operative ASD (O-ASD), S-ASD requiring revision surgery. RESULTS: Incidences of each ASD at 2, 5, and 10 years after primary PLIF were 19%, 49%, and 75% for R-ASD, 6%, 14%, and 31% for S-ASD, and 5%, 9%, and 15% for O-ASD, respectively. O-ASD incidence was 24% at final follow-up. O-ASD peak was bimodal, at 2 and 10 years after primary PLIF. O-ASD was mainly observed at the cranial segment (77%), followed by the caudal segment (13%) and both cranial and caudal segments (10%). With respect to O-ASD pathology, degenerative spondylolisthesis was observed in 52%, spinal stenosis in 39%, and disc herniation in 10%. CONCLUSION: Incidences of R-ASD, S-ASD, and O-ASD at 10 years after primary PLIF were 75%, 31%, and 15%, respectively. With respect to O-ASD pathology, degenerative spondylolisthesis at the cranial segment was the most frequent. LEVEL OF EVIDENCE: 4.

Prevalence of Diffuse Idiopathic Skeletal Hyperostosis in Patients with Spinal Disorders.

STUDY DESIGN: Retrospective cohort study. PURPOSE: The purpose of this study was to evaluate the prevalence of diffuse idiopathic skeletal hyperostosis (DISH) in patients with spinal diseases determined by roentgen images of the whole spine. OVERVIEW OF LITERATURE: Although several studies have investigated the prevalence of DISH in healthy subjects, no detailed data have been reported on the prevalence of DISH in patients with degenerative spinal disorders. METHODS: Standing whole-spine roentgen images of 345 consecutive patients who underwent surgery in our hospital were obtained. Patients aged <18 years or with congenital spinal disease, metastatic spinal tumors, or inflammatory spinal disease were excluded. In total, 281 patients were eligible for inclusion. The presence of DISH was assessed according to Resnick's criteria and Mata's scoring system. The prevalence, location, and numbers of fused vertebral bodies of DISH were recorded. RESULTS: DISH was present in 25.6% of patients (72/281). The prevalence of DISH in the 41-49, 50-59, 60-69, 70-79, and ≥80 year age groups was 8.3% (2/24), 9.8% (5/51), 16.0% (12/75), 49.5% (48/97), and 33.3% (4/12), respectively; the prevalence increased with age. The average number of fused vertebral bodies was 7.5. More than 80% of DISH was located from T7 to T11, and more than 95% of DISH was located at T9/10. Patients with DISH were significantly older (71.1 years vs. 60.9 years, p<0.05), and men were more likely to have DISH than women (p<0.05). CONCLUSIONS: In patients with degenerative spinal diseases with DISH, fused vertebrae were found most frequently in the lower thoracic spine, and their prevalence increased with age. DISH may be an age-related skeletal disorder with a higher overall prevalence in patients with spinal disorders than that in healthy subjects.

Spinopelvic sagittal imbalance as a risk factor for adjacent-segment disease after single-segment posterior lumbar interbody fusion.

Objective: The importance of spinopelvic balance and its implications for clinical outcomes after spinal arthrodesis has been reported in recent studies. However, little is known about the relationship between adjacent-segment disease (ASD) after lumbar arthrodesis and spinopelvic alignment. The purpose of this study was to clarify the relationship between spinopelvic radiographic parameters and symptomatic ASD after L4­5 single-level posterior lumbar interbody fusion (PLIF). Methods: This was a retrospective 1:5 matched case-control study. Twenty patients who had undergone revision surgery for symptomatic ASD after L4­5 PLIF and had standing radiographs of the whole spine before primary and revision surgeries were enrolled from 2005 to 2012. As a control group, 100 age-, sex-, and pathology-matched patients who had undergone L4­5 PLIF during the same period, had no signs of symptomatic ASD for more than 3 years, and had whole-spine radiographs at preoperation and last follow-up were selected. Mean age at the time of primary surgery was 68.9 years in the ASD group and 66.7 years in the control group. Several radiographic spinopelvic parameters were measured as follows: sagittal vertical axis (SVA), thoracic kyphosis (TK), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), and segmental lordosis at L4­5 (SL) in the sagittal view, and C7­central sacral vertical line (C7-CSVL) in the coronal view. Radiological parameters were compared between the groups. Results: No significant change was found between pre- and postoperative radiographic parameters in each group. In terms of preoperative radiographic parameters, the ASD group had significantly lower LL (40.7° vs 47.2°, p < 0.01) and significantly higher PT (27° vs 22.9°, p < 0.05) than the control group. SVA ≥ 50 mm was observed in 10 of 20 patients (50%) in the ASD group and in 21 of 100 patients (21%, p < 0.01) in the control group. PI-LL ≥ 10° was noted in 15 of 20 patients (75%) in the ASD group and in 40 of 100 patients (40%, p < 0.01) in the control group on preoperative radiographs. Postoperatively, the ASD group had significantly lower TK (22.5° vs 30.9°, p < 0.01) and lower LL (39.3° vs 48.1°, p < 0.05) than the control group had. PI-LL ≥ 10° was seen in 15 of 20 patients (75%) in the ASD group and in 43 of 100 patients (43%, p < 0.01) in the control group. Conclusions: Preoperative global sagittal imbalance (SVA > 50 mm and higher PT), pre- and postoperative lower LL, and PI-LL mismatch were significantly associated with ASD. Therefore, even with a single-level PLIF, appropriate SL and LL should be obtained at surgery to improve spinopelvic sagittal imbalance. The results also suggest that the achievement of the appropriate LL and PI-LL prevents ASD after L4­5 PLIF.