L5 Slope Research Articles

Radiological and clinical outcomes of midline lumbar fusion on sagittal lumbar-pelvic parameters for degenerative lumbar diseases.

Improving the sagittal lumbar-pelvic parameters after fusion surgery is important for improving clinical outcomes. The impact of midline lumbar fusion (MIDLF) on sagittal lumbar-pelvic alignment for the management of degenerative lumbar diseases is still unknown. To analyze the effects of short-segment MIDLF and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) on sagittal lumbar-pelvic parameters. We retrospectively analyzed 63 patients with degenerative lumbar diseases who underwent single-segment MIDLF or MIS-TLIF. The imaging data of patients were collected before surgery and at the final follow-up. The radiological sagittal parameters included the lumbar lordosis (LL), lower LL, L4 slope (L4S), L5 slope (L5S), L5 incidence (L5I), L1 axis and S1 distance (LASD), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and PI-LL mismatch (PI-LL). Additionally, the clinical outcomes, including lower back and leg pain visual analog scale (VAS) and Oswestry disability index (ODI) scores, were also analyzed. In both groups, LL and Lower LL significantly increased, while L5I and LASD significantly decreased at the final follow-up compared to that recorded prior to operation (P < 0.05). In the MIDLF group, L4S significantly decreased compared to that recorded prior to operation (P < 0.05), while the mean SS significantly increased and the PT significantly decreased compared to that recorded prior to operation (P < 0.05). In the MIS-TLIF group, SS slightly increased and the mean PT value decreased compared to that recorded prior to operation, but without a statistically significant difference (P > 0.05). However, the PI-LL in both groups was significantly reduced compared to that recorded prior to operation (P < 0.05). There was no significant difference in the sagittal lumbar-pelvic parameters between the two groups prior to operation and at the final follow-up (P > 0.05). In addition, the change in sagittal lumbar-pelvic parameters did not differ significantly, except for ΔLASD within the two groups (P > 0.05). The mean lower back and leg pain VAS and ODI scores in both groups were significantly improved three months after surgery and at the final follow-up. Though the mean ODI score in the MIDLF group three months after surgery was slightly higher than that in the MIS-TLIF group, there was no significant difference between the two groups at the final follow-up. Short-segment MIDLF and MIS-TLIF can equally improve sagittal lumbar parameters such as LL, Lower LL, L5I, and LASD in the treatment of lumbar degenerative diseases. However, MIDLF had a larger impact on pelvic parameters than MIS-TLIF.

Risk factors for L5 pedicle fractures after single-level posterior spinal fusion

BACKGROUND CONTEXTPedicle fractures are a rare but potentially devastating complication of posterior instrumented spinal fusion (PSF). Preoperative awareness of the possible risk factors may help prevent these fractures by modifying the surgical plan. However, the risk factors have not yet been identified. PURPOSETo determine the preoperative parameters associated with postoperative L5 pedicle fracture after L4/5 PSF. STUDY DESIGNCase control study. PATIENT SAMPLEPatients undergoing L4/5 PSF at a single academic institution between 2014 and 2020. OUTCOME MEASURESOccurrence of postoperative L5 pedicle fracture. METHODSOf 253 patients (female:male, 145:108) undergoing L4/5 PSF from 2014 to 2020, patients with postoperative L5 pedicle fractures were identified retrospectively as “cases” (n = 8, all female, age: 70 ± 10.7 years). As a control group all remaining patients with a follow-up of more than 12 months were allocated (n = 184, 104 females, age: 64.27 ± 13.00 years). In all but 16 cases, anterior support with transforaminal or posterior interbody fusion was performed. Demographic and clinical data (body mass index (BMI)), surgical factors, and comorbidities) were compared. Radiological assessment of spinopelvic parameters was performed using pre- and postoperative standing lateral radiographs. RESULTSThe overall incidence of L5 pedicle fractures after L4/5 spinal fusion was 3.16%, with a median time from index surgery to diagnosis of 25 days (range, 6–199 days) (75% within the first 32 days postoperatively). Patients with L5 pedicle fractures had higher pelvic incidence (PI) (71° ± 9° vs. 56° ± 11°; p=.001), sacral slope (SS) (45° ± 7° vs. 35° ± 8°; p=.002), L5 slope (30° ± 11° vs. 15° ± 10°, p=.001), L5 incidence (42° ± 14° vs. 26° ± 11°; p= .003), L1-S1 lumbar lordosis (LL) postop (57° ± 10° vs. 45° ± 11°; p=.006), and L4 -S1 LL postop (33° ± 7° vs. 28° ± 7°; p=.049) compared with the control group. Pelvic tilt and PI- LL mismatch were not significantly different. Female gender was a significant risk factor for L5 pedicle fractures (p=.015). BMI (kg/m2) was statistically equal in patients with or without pedicle fractures (28.37 ± 5.96 vs. 28.53 ± 16.32; p=.857). There was no significant difference between the groups for approximative bone mineral density assessment (Hounsfield units; 113 ± 60 vs. 120 ± 43; p=.396) using the L3 trabecular region of interest (ROI) measurement. The correlation analysis demonstrated that most of the identified risk factors except for the postoperative L4-S1 lordosis show significant positive associations among each other. All eight patients in the fracture group underwent revision surgery, and the instrumented fusion was extended to the sacrum, with the addition of sacral-alar-iliac or iliac screws, in six cases. CONCLUSIONSL5 pedicle fractures occurred in 3% of the patients after single level L4/5 PSF. Risk factors are female gender, higher PI, SS, L5 slope, L5 incidence, and LL postop but not high BMI. These findings can be used for surgical planning and decision of fusion levels.

P103. Sagittal alignment after mini open vertebral body tether versus posterior fusion for adolescent idiopathic scoliosis

BACKGROUND CONTEXT Sagittal alignment is integral to a patient's quality of life. Posterior spinal fusion (PSF) is currently the standard for correcting adolescent idiopathic scoliosis (AIS). Vertebral body tethering (VBT) is a fusionless growth modulating surgical technique used to treat AIS. It relies on the Hueter-Volkmann Law. Indications for this procedure include patients who have coronal curves up to 50 °, growth remaining, and no excessive thoracic kyphosis. VBT has been shown to have good coronal plane deformity correction. There have been less examinations of the sagittal effects of VBT. Sagittal alignment is significantly associated with a patient's quality of life. This underscores the importance of sagittal alignment when correcting the coronal deformity in these patients. PURPOSE We show that VBT for correction of AIS is non-inferior with regards to sagittal alignment compared to PSF. STUDY DESIGN/SETTING Retrospective review of AIS patient treated by VBT and PSF at a single medical center. PATIENT SAMPLE Data was collected from our AIS database of VBT and PSF fusion patients. OUTCOME MEASURES Our outcome measures are sagittal vertical axis (SVA), cervical SVA (cSVA), pelvic tilt (PT), thoracic kyphosis (TK), cervical lordosis (CL), L4-S1 lordosis, L5 slope, T1 pelvic angle (TPA) and pelvic incidence lumbar lordosis mismatch (PI-LL). METHODS We propensity matched by age, Risser score and Lenke classification. We compared preoperative and postoperative sagittal parameters measured by Surgimap with statistical significance set at p<0.050. RESULTS Comparing PSF to VBT there was no statistically significant difference in change between preoperative and postoperative cSVA (-.45, SD=6.85 vs .97, SD=5.59, P=.48); PT (4.12, SD=6.49 vs 3.41, SD=4.50, P=.68); TK (1.65, SD=12.12 vs -1.59, SD=10.49, P=.35); CL (3.62, SD=8.87 vs 9.04, SD=13.82, P=.16); L4-S1 lordosis (3.25, SD=7.78 vs 6.09, SD=10.19 , P=.34); SVA (-14.95, SD=30.92 vs -26.82, SD=35.76, P=.34); L5 slope (-1.36, SD=5.91vs -2.95, SD=5.43, P=.44); TPA (4.42, SD=7.69 vs 5.21, SD=6.40, P=.74); and PI-LL (5.48, SD=10.96 vs 6.49, SD=10.80 P=.76). CONCLUSIONS VBT and PSF for AIS result in statistically similar changes in sagittal alignment parameters. The fact that we showed similar results comparing sagittal alignment in fusion and VBT groups indicates that VBT is non-inferior from a sagittal perspective. It is important to maintain sagittal alignment when correcting AIS. Future work can examine the long-term effect of VBT on sagittal alignment. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Sagittal alignment is integral to a patient's quality of life. Posterior spinal fusion (PSF) is currently the standard for correcting adolescent idiopathic scoliosis (AIS). Vertebral body tethering (VBT) is a fusionless growth modulating surgical technique used to treat AIS. It relies on the Hueter-Volkmann Law. Indications for this procedure include patients who have coronal curves up to 50 °, growth remaining, and no excessive thoracic kyphosis. VBT has been shown to have good coronal plane deformity correction. There have been less examinations of the sagittal effects of VBT. Sagittal alignment is significantly associated with a patient's quality of life. This underscores the importance of sagittal alignment when correcting the coronal deformity in these patients. We show that VBT for correction of AIS is non-inferior with regards to sagittal alignment compared to PSF. Retrospective review of AIS patient treated by VBT and PSF at a single medical center. Data was collected from our AIS database of VBT and PSF fusion patients. Our outcome measures are sagittal vertical axis (SVA), cervical SVA (cSVA), pelvic tilt (PT), thoracic kyphosis (TK), cervical lordosis (CL), L4-S1 lordosis, L5 slope, T1 pelvic angle (TPA) and pelvic incidence lumbar lordosis mismatch (PI-LL). We propensity matched by age, Risser score and Lenke classification. We compared preoperative and postoperative sagittal parameters measured by Surgimap with statistical significance set at p<0.050. Comparing PSF to VBT there was no statistically significant difference in change between preoperative and postoperative cSVA (-.45, SD=6.85 vs .97, SD=5.59, P=.48); PT (4.12, SD=6.49 vs 3.41, SD=4.50, P=.68); TK (1.65, SD=12.12 vs -1.59, SD=10.49, P=.35); CL (3.62, SD=8.87 vs 9.04, SD=13.82, P=.16); L4-S1 lordosis (3.25, SD=7.78 vs 6.09, SD=10.19 , P=.34); SVA (-14.95, SD=30.92 vs -26.82, SD=35.76, P=.34); L5 slope (-1.36, SD=5.91vs -2.95, SD=5.43, P=.44); TPA (4.42, SD=7.69 vs 5.21, SD=6.40, P=.74); and PI-LL (5.48, SD=10.96 vs 6.49, SD=10.80 P=.76). VBT and PSF for AIS result in statistically similar changes in sagittal alignment parameters. The fact that we showed similar results comparing sagittal alignment in fusion and VBT groups indicates that VBT is non-inferior from a sagittal perspective. It is important to maintain sagittal alignment when correcting AIS. Future work can examine the long-term effect of VBT on sagittal alignment.

Differences in Sagittal Balance in Patients with and without Degenerative Spondylolisthesis Who are Surgically Treated for Spinal Stenosis. A Comparative Study

Introduction: In pathogenesis of degenerative spondylolisthesis (DS) and its development, several predisposing factors have been advocated. However, the role of lumbar sagittal alignment has not been well studied yet. The purpose of this retrospective study was to analyze the sagittal spinopelvic alignment and to compare these parameters between patients with and without degenerative spondylolisthesis who were surgically treated for lumbar spinal stenosis. Materials and Methods: Between 2008-2018, we studied 68 patients who underwent surgery for lumbar spinal canal stenosis. 34 of these patients, suffered by DS (group 1), and the other 34, age- and gender-matched patients, not presented DS (group 2). Surgical treatment was realized after six months of unsuccessful conservative treatment. Spinopelvic parameters including pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), L4 slope, L5 slope, thoracic kyphosis (TK), lumbar lordosis (LL), segmental lumbar lordosis (SLL) and sagittal balance were compared between the two groups. In the group 1, the slippage grade (% slip) was also evaluated. Results: PI, SS, L4 slope, L5 slope, TK and LL in the group 1 were significantly greater than those in the group 2, and PI had positive correlation with % slip (p<0.05). The SLL of patients with DS was significantly lower than those without DS. In the group 1, there was a strong correlation between the PI and the SS (p<0.001), rather than with the PT (p<0.01). Between the two groups there was no significant difference in PT. Conclusions: In patients with degenerative spondylolisthesis, PI was significantly greater than that in patients without DS and PI had positive correlation with the percentage of slippage. Greater PI turns to be a predisposing factor to the development and the progression of vertebral sliding. On the other hand, patients who suffered by degenerative lumbar stenosis without sliding, have a normal PI. In patients with DS, a predisposing condition for an anterior displacement of L4 on L5, was represented by the increased vertical inclination of the S1 endplate. In these patients, segmental lordosis was increased at the levels above L4/L5.

Sagittal reconstruction of lumbosacral contiguous double-level spondylolytic spondylolisthesis: a comparison of double-level and single-level transforaminal lumbar interbody fusion

BackgroundContiguous double-level lumbar spondylolytic spondylolisthesis is an extremely rare condition. There is a paucity of data of lumbosacral deformity and sagittal spino-pelvic malalignment among these patients. Moreover, the effect of transforaminal lumbar interbody fusion (TLIF) on sagittal realignment still remains largely unknown. The aim of the study is to investigate the reconstruction of sagittal alignment and the improvement of clinical outcomes after posterior instrumented double-level or single-level TLIF.MethodsFrom January 2010 to September 2018, the records of patients with contiguous L4/5 and L5/S1 double-level spondylolytic spondylolisthesis were retrospectively reviewed. Patients who had undergone double-level or single-level TLIF and a minimum of 2 years’ follow-up were included. The slippage parameters and spino-pelvic parameters were measured preoperatively, postoperatively, and at the latest follow-up.ResultsA total of 58 patients (21 males and 37 females, mean age of 57.1 ± 6.9 years) were enrolled. Thirty-eight patients were treated with double-level TLIF and the remaining 20 with single-level TLIF (L4/5 in 14; L5/S1 in 6). After surgery, the spondylolisthesis was significantly reduced at both L4/5 and L5/S1 level (all P < 0.001). There was a significant reduction in pelvic tilt (P < 0.001) and a significant increase in sacral slope (P < 0.001). Significant increase in L4–S1 height (P < 0.001) and L4–S1 lordosis (P = 0.012) and decrease in L5 slope (P = 0.004) and L5 incidence (P = 0.001) were also observed. Compared to single-level TLIF, double-level TLIF increased L4–S1 height (P < 0.001) and L4–S1 lordosis (P < 0.001) and reduced L4-SVA (P = 0.007) and L5 incidence (P = 0.013) more obviously, and the sagittal balance was better corrected in double-level TLIF group (P = 0.006). Double-level TLIF group showed larger increase in VAS scores for low back pain. The incidence of implant-related complications was lower in the double-level group.ConclusionPosterior short-segment instrumented TLIF can bring favorable radiographic and clinical outcomes in patients with lumbosacral contiguous double-level spondylolytic spondylolisthesis. Double-level TLIF is more efficient to improve L4–S1 height, regional lumbar lordosis, and global sagittal balance.

EFFECTS OF SAGITTAL BALANCE DIFFERENCES ON SPONDYLOLISTHESIS.

ABSTRACTObjectives:This study aimed to compare the lumbar lordosis (LL) and spinopelvic parameters of patients with stage 1–2 spondylolisthesis to those of the normal population and demonstrate the importance of these parameters in sagittal balance.Methods:The lumbosacral parameters on the lateral radiographs of a total of 125 patients were retrospectively compared. Lumbosacral parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis angle (LLA), L5 incidence (L5I), L5 slope (L5S), and sacral table angle (STA) were compared between groups.Results:Comparison of the parameters between groups revealed no sex-based differences (p > 0.05).Conclusions:Abnormal sagittal spinopelvic parameters are commonly examined for their effects on the development of spondylolisthesis and should be used in routine practice. We found that the low SS values in our study, unlike those of other similar studies, may be a compensatory mechanism developed to reduce pain and maintain sagittal balance. Level of Evidence II; retrospective study.

Potential pathological mechanisms of L3 degenerative spondylolisthesis in lumbar spinal stenosis patients: A case–control study

BackgroundDegenerative spondylolisthesis (DS) occurs mostly at L4. However, there are a small number of patients in whom it occurs only at L3. Accordingly, past reports elucidating the factors of DS have been primarily concerned with L4 DS, and few reports are available on DS at L3. The objective of this study was to compare the differences between lumbar spinal stenosis patients with or without L3 DS and to identify the possible pathological mechanisms of their L3 DS. MethodsAmong the 369 patients with lumbar spinal stenosis who underwent lumbar surgery, we assessed 25 patients who had DS only at L3 and compared them against 50 other age- and gender-matched lumbar spinal stenosis patients without any DS. The following radiographic parameters: pelvic incidence, sacral slope, pelvic tilt, L3 slope, L4 slope, L5 slope, and lumbar lordosis were measured on radiographs. The orientation of facet joints and disc heights were measured via computed tomography. ResultsImaging findings showed that the L3, L4, and L5 slopes in the L3 DS group were significantly greater than in the non-DS group, and only L3/4 facet joints in the L3 DS group were significantly more sagittally oriented than in the control group. The number of patients with low disc heights at L4/5 in the L3 DS group was significantly greater than in the control group. ConclusionsThe results suggested that the greater lumbar slope, including L3 together with more sagittally oriented facet joints only at L3/4 and not at L4/5, may lead to DS only at L3.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P33. The prevalence of L4-5 degenerative spondylolisthesis in females: role of spinal sagittal alignment and lumbopelvic morphology

BACKGROUND CONTEXT L4/5 degenerative spondylolisthesis (L4DS) is a common radiographic finding and predisposing factors, such as increased lumbar lordosis (LL), pelvic incidence (PI), L5 vertebral slope, and sagittal orientation of the facet joint have been reported. Among female subjects aged >65years, prevalence of L4DS was reported to be 29%, which was 1.3- to 6.4-fold higher than male subjects. However, there are few studies investigating the factors associated with the gender difference of L4DS. PURPOSE The purpose of this study is to clarify radiographic factors of L4DS with a focus on gender-specific difference in spinal sagittal alignment and lumbopelvic morphology. STUDY DESIGN/SETTING This is a prospective study. PATIENT SAMPLE Consecutive 110 patients with symptomatic lumbar canal stenosis (LCS) who underwent upright whole spine X-ray imaging, myelography, CT and MRI between 2012 and 2017 were reviewed, and those with L4/5 LCS 5% anterior slip) were excluded. A final total of 86 subjects were included, and L4DS were found in 51; 30 females (L4DSF, 70.1±8.9 years) and 21 males (L4DSM, 69.7±10.4 years), and LCS was found in 35; 12 females (LCSF, 76.8±6.4 years) and 21 males (LCSM, 67.8±8.8 years). OUTCOME MEASURES Radiographic measurement included LL, PT, L5 slope, S1 slope (SS), sagittal vertical axis (SVA), pelvic incidence (PI), disc height (DH; average of anterior and posterior disc height), L4/5 facet orientation (FOR; the angle between bilateral facet by CT), L4/5 facet osteoarthritis (FOA; grade 1 normal to grade 4 severe OA by CT), and L4/5 disc degeneration (Pfirrmann grading by MRI). METHODS In these parameters, the significant differences between LCS and L4DS in female and male were evaluated. ANOVA was used for statistical analyses and significance level was set at p RESULTS Following parameters showed significant differences; PT between gender (female 21.2±9.3, male 17.2±7.5, p=.03) and between L4DS and LCS (L4DS 20.7±8.6, LCS 16.9±8.2, p=.040), LL between L4DSF and LCSF (L4DSF 42.7±11.7, LCSF 34.5±12.0, p=.048), L5 slope between L4DS and LCS༈L4DS 16.5±7.5, LCS 13.0±9.0, p=.049; L4DSF 16.9±9.1, LCSF 8.2±11.3, p=.002), L4/5 FOR between L4DS and LCS ༈L4DS 61.7±17.9, LCS 80.2±15.0, p CONCLUSIONS L4DS showed female predominance even among symptomatic LCS patients. L4/5 FOR and FOA were associated with L4DS regardless of gender, however, influence of sagittal alignment and lumbopelvic morphology were more prevalent among female patients than male counterpart, which might explain gender difference of DS incidence. Current study substantiated previous studies using multimodal evaluations, and further studies of muscle strength, joint laxity, and other clinical factors might be necessary for understanding gender-specific incidence of DS.

The pelvic radius technique in the assessment of spinopelvic sagittal alignment of degenerative spondylolisthesis and lumbar spinal stenosis

BackgroundDegenerative spondylolisthesis (DS) and lumbar spinal stenosis (LSS) are the most common degenerative spinal diseases. The evaluating of spinopelvic sagittal alignment of the two diseases using pelvic radius (PR) technique have not been reported. The purpose of this study was to use PR measurement technique to compare the differences in spinopelvic sagittal alignment between DS and LSS. MethodsA total of 145 patients with DS or LSS were retrospectively reviewed. Seventy patients with DS (DS group) and 75 age-matched patients with LSS (LSS group) were enrolled. Spinopelvic parameters including pelvic angle (PA), regional lumbopelvic lordosis (PR–L1, PR–L2, PR–L3, PR–L4 and PR–L5), total lumbopelvic lordosis (PR–T12), pelvic morphology (PR–S1), sagittal vertical axis from the C7 plumb line (SVA), lumbar lordosis (LL), thoracic kyphosis (TK), L4 slope and L5 slope were assessed in the two groups. Several parameters of DS and LSS group were compared with the normal population (NP). ResultsThe PR–L4, PR–L5 and PR-S1 in the DS group were significantly smaller than those in the LSS group. There was no difference in PR–T12 between the DS group and NP (p > 0.05), while PR–T12 of the LSS group were significantly lower (p < 0.01). Degree of correlations among spinopelvic parameters differed between the two groups. PR–T12 of the DS group was more strongly correlated with PA (r = −0.829, p < 0.001) than with LL (r = 0.664, p < 0.001), TK (r = 0.582, p < 0.001). PR-T12 of the LSS group was more strongly correlated with LL (r = 0.854, p < 0.001), TK (r = 0.616, p < 0.001) than with PA (r = −0.582, p < 0.001). ConclusionsPR–L4 and PR–L5 may be the predisposing factors for DS development. Spinopelvic morphology differed in patients with DS and LSS compared to NP. The compensatory mechanisms to maintain spinopelvic sagittal alignment in DS and LSS patients may be different.

L5 incidence: an important parameter for spinopelvic balance evaluation in high-grade spondylolisthesis

BackgroundIn high-grade spondylolisthesis (HGSPL), the pelvic incidence (PI) is not a reliable measurement because of doming of the sacrum. Measurement of L5 incidence (L5I) was described as a tool to measure pelvic morphology in HGSPL and for surgical follow-up. ObjectiveWe aimed to evaluate L5I in HGSPL and its relationship to other spinopelvic parameters. Study DesignA retrospective study of a cohort of 184 patients with HGSPL was carried out. MethodsWhole spine radiographs were analyzed for PI, pelvic tilt (PT), sacral slope, lumbar lordosis (LL), L5I, L5 tilt (L5T), L5 slope, lumbosacral kyphosis, and slip percentage. Statistical analysis and correlation were made (Pearson correlation test; p<.05). In accordance to Cohen, statically significant correlation were considered strong if R>0.5, moderate if 0.3<R<0.5, and small if R<0.3. ResultsA total of 184 cases were analyzed, with a female-to-male ratio of 2.35 and a mean age of 20.1 years. Sacral doming was present in 73% of the cases. Mean L5I incidence was 65.2° and strongly correlated to other sagittal parameters, especially PT (R=0.7), LL (R=0.7), L5T (R=0.77), and L5 slope (R=0.83). There was less but still strong correlation to Dubousset lumbosacral kyphosis (Dub-LSK) angle (R=−0.63) and percentage of slippage (R=0.56). L5 tilt showed nearly perfect correlation to PT (R=0.95). Forty-four percent of the cases were balanced HGSPL, whereas 56% of the cases were unbalanced HGSPL. L5 incidence was found to be a good predictor of local imbalance with a cutoff of L5I=61. ConclusionThis paper describes L5I, which is a positional parameter in HGSPL. L5 incidence is a simple and reliable measure in the preoperative setting in HGSPL. Its correlation with spinal sagittal parameters (especially PT and LL) is strong and was found to be better than Dub-LSK. There is also a good correlation between L5I and HGSPL pelvic parameters (slip percentage and lumbosacral kyphosis). We recommend its use for evaluation of surgical correction and recommend the value of 60° as cutoff value to define spinopelvic balance in HGSPL.

Differences of Sagittal Lumbosacral Parameters between Patients with Lumbar Spondylolysis and Normal Adults.

Background:Recent studies have suggested an association between elevated pelvic incidence (PI) and the development of lumbar spondylolysis. However, there is still lack of investigation for Han Chinese people concerning the normal range of spinopelvic parameters and relationship between abnormal sagittal parameters and lumbar diseases. The objective of the study was to investigate sagittal lumbosacral parameters of adult lumbar spondylolysis patients in Han Chinese population.Methods:A total of 52 adult patients with symptomatic lumbar spondylolysis treated in the General Hospital of Armed Police Force (Beijing, China) were identified as the spondylolysis group. All the 52 patients were divided into two subgroups, Subgroup A: 36 patients with simple lumbar spondylolysis, and Subgroup B: 16 patients with lumbar spondylolysis accompanying with mild lumbar spondylolisthesis (slip percentage <30%). Altogether 207 healthy adults were chosen as the control group. All patients and the control group took lumbosacral lateral radiographs. Seven sagittal lumbosacral parameters, including PI, pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), L5 incidence, L5 slope, and sacral table angle (STA), were measured in the lateral radiographs. All the parameters aforementioned were compared between the two subgroups and between the spondylolysis group and the control group with independent-sample t-test.Results:There were no statistically significant differences of all seven sagittal lumbosacral parameters between Subgroup A and Subgroup B. PI, PT, SS, and LL were higher (P < 0.05) in the spondylolysis group than those in the control group, but STA was lower (P < 0.001) in the spondylolysis group.Conclusions:Current study results suggest that increased PI and decreased STA may play important roles in the pathology of lumbar spondylolysis in Han Chinese population.

Normative values for the L5 incidence in a subgroup of transitional anomalies extracted from 147 asymptomatic subjects.

Pelvic incidence angle is not always measurable due to lumbosacral transitional vertebrae (LSV). The fifth lumbar vertebra (L5) is rarely abnormal. The purpose of this study was to quantify from full-body standing X-rays, the L5 incidence angle (L5I) in a normal asymptomatic population and to correlate it with standard spino-pelvic parameters taking the sacrum (S1) as a reference. One hundred and forty seven asymptomatic volunteers were enrolled. The ethics committee approved the study protocol. Subjects underwent a low-dose full spine X-ray. 3D reconstructions were obtained and L5I was measured using the upper L5 endplate as the reference instead of the S1 endplate. A group of subjects with LSV was identified and subdivided in two subgroups. Standard spino-pelvic parameters and normative values for the L5 parameters were obtained. Statistical correlations were calculated between the standard and L5 parameters as well as L5I with L1-L5 lordosis in both subgroups. Twenty two (14.96%) subjects with LSV were found. Ten of these had an unidentifiable S1 endplate due to a sacralisation of L5. Mean values for the L5I, L5 tilt, L5 slope and L1-L5 lordosis were, respectively, 22.43, 4.65, 17.73, and 45.51 for normal subjects (N=137) and 32.75, 6.63, 26.38, and 55.02 for sacralisation of L5 subjects (N=10). Mathematical relationship found: L5I=0.7641*PI-17.725 (R=0.83) and L1-L5=0.67*L5I+30.7 (R=0.64). This prospective study is first to provide normative spino-pelvic values at the L5 level in an asymptomatic population, particularly in case of (LSV) sacralisation of L5 (N=10) where L5I and L1-L5 lordosis appears to be 10° more important than in normal population. We propose L5I as a new spino-pelvic parameter to restore in case of L5-S1 disk disease. These normative values will help to control peri-operatively the adequate lordosis restoration, in the presence of LSV.

IMMEDIATE RECIPROCAL CHANGES AT ADJACENT LEVEL FOLLOWING SINGLE-LEVEL ALIF

Objective : To assess the segmental sagittal parameters and the adjacent mobile segment after interbody fusion by anterior approach in single-level L5-S1. Methods : Retrospective study. Inclusion: Interbody fusion by anterior approach (10°/15° angle), due to DDD, low-grade spondylolisthesis and/or stenosis without prior lumbar fusion. Thirty-five cases were included (25 women; mean age 47±15 years). Analysis of lumbar radiographs were performed preoperatively and 3 months after surgery. The following parameters were evaluated: lumbar lordosis; segmental lordosis L4-L5 and L5-S1; sacral and L5 slope. Two independent evaluators made the measurements. Student's t test was used. Results : There was correction of lordosis at the L5-S1 level, from an average of 19° prior to surgery to 28° three months after surgery (p&lt;0.001). It was observed reduction of the L4-L5 angle from 17° to 14° (p &lt;0.001). Moreover, there was a small, but statistically significant, reduction of L5 inclination from 17 ° to 13 ° (p=0.007) and increase in the sacral slope from 37° to 40° (p=0.002). The change of total lumbar lordosis was not significant: 52° versus 53° (p=0.461). Before surgical correction, lordosis of the L5-S1 level contributed, on average, 37% of lumbar lordosis, and after, 54% (p&lt;0.001). The L4-L5 level accounted for 34% and decreased to 24% (p&lt;0.001). Conclusion : In the group studied, it was observed a decrease in lordosis of the adjacent mobile level following the treatment of the degenerate level by anterior interbody fusion and concomitant increase in lordosis.

Pelvic retroversion is the key protective mechanism of L4-5 degenerative spondylolisthesis.

To explore the role of spinopelvic sagittal alignment in the pathological mechanism of degenerative spondlylolisthesis (DS) development. A total of 52 asymptomatic volunteers, 32 single segment L4-5 DS and 29 lumbar spinal stenosis (LSS) without spondylolisthesis patients were enrolled. All subjects had standard lumbar spine X-ray films with standard position along with lumbar spine magnetic resonance image. Comparative analysis of sagittal parameters and disc degeneration grades among asymptomatic volunteers and patients with the two disorders were performed. Compared to normal population (NP) and LSS, DS showed significantly greater pelvic incidence (PI), sacral slope (SS) and lumbar lordosis (LL), while LSS showed significantly smaller PT and PT/SS. DS showed significantly greater L5 slope than NP and LSS. In both Great-PI group and Small-PI group, all above differences between DS and LSS remained. LSS showed significantly higher degenerative grade of each adjacent disc than DS. Population with adjacent segment degeneration showed higher incidence of pelvic retroversion (PT/SS ≥1), and LSS showed greater proportion of adjacent segment degeneration than DS. Lumbar spine morphology of great LL determined by great PI is a risk factor of L4-5 DS. L5 slope is a parameter that can be used to predict the risk of L4-5 DS. Pelvic retroversion is the key protective mechanism from DS. Adjacent segment degeneration is a driving factor of pelvic retroversion for compensation of lumbar sagittal malalignment.

Comparative study of spinopelvic sagittal alignment between patients with and without degenerative spondylolisthesis

To date, few studies have focused on spinopelvic sagittal alignment as a predisposing factor for the development of degenerative spondylolisthesis (DS). The objectives of this study were to compare differences in spinopelvic sagittal alignment between patients with or without DS and to elucidate factors related to spinopelvic sagittal alignment. A total of 100 patients with or without DS who underwent surgery for lumbar spinal canal stenosis were assessed in this study. Fifty patients with DS (DS group) and 50 age- and gender-matched patients without DS (non-DS group) were enrolled. Spinopelvic parameters including pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), L4 slope, L5 slope, thoracic kyphosis (TK), lumbar lordosis (LL) and sagittal balance were compared between the two groups. In the DS group, the percentage of vertebral slip (% slip) was also measured. Several spinopelvic parameters, PI, SS, L4 slope, L5 slope, TK and LL, in the DS group were significantly greater than those in the non-DS group, and PI had positive correlation with % slip (r=0.35, p<0.05). Degrees of correlations among spinopelvic parameters differed between the two groups. In the DS group, PI was more strongly correlated with SS (r=0.82, p<0.001) than with PT (r=0.41, p<0.01). In the non-DS group, PI was more strongly correlated with PT (r=0.73, p<0.001) than with SS (r=0.38, p<0.01). Greater PI may lead to the development and the progression of vertebral slip. Different compensatory mechanisms may contribute to the maintenance of spinopelvic sagittal alignment in DS and non-DS patients.

Lumbar muscle fatigue and subjective health measurements in patients with lumbar disc herniation 2 years after surgery

In this prospective study the purpose was to evaluate patients with lumbar-disc herniation regarding changes in back-muscle fatigue and subjective health measurements 2years after surgery. Endurance time, EMG median frequency and ratings of lumbar-muscle fatigue and pain were measured before surgery, 4weeks after and 2years after surgery in 26 patients (19 men and 7 women) with lumbar-disc herniation. A modified Sørensen test was performed with concurrent recordings of electromyography from the lumbar muscles at four recording sites. The questionnaires Oswestry disability index, Roland-Morris disability questionnaire, Self-efficacy scale, SF-36, Back beliefs questionnaire, Odom and a 6-grade physical activity scale were used. Two years after surgery the patients had longer endurance times (increase from 178s to 231s, p<0.001), a non-significant tendency for flatter L5 slopes (decrease from -0.20 to -0.16Hz/s, p<0.066), higher initial median frequency (L1 increase from 58 to 64Hz p<0.001, L5 increase from 76 to 84Hz p=0.001) and improved questionnaire scores. The questionnaires Oswestry, Roland-Morris and SF-36 physical functioning correlated with the endurance time 0.69-0.93 and with L5 slope 0.01-0.93 and the highest correlations were found in women. Both EMG and endurance time measurements are needed for evaluating fatigue in lumbar-disc herniation.

Back extensor muscle fatigue in patients with lumbar disc herniation

We investigated back muscle fatigue and endurance in patients with lumbar disc herniation before and after surgery, and established the degree of association between perceived fatigue and objectively measured fatigue. Additionally, the relationships between muscle fatigue and endurance time on the one hand, and activity, participation, self-efficacy and health on the other, were investigated to clarify the grades of association between these factors. Forty-three consecutive patients with lumbar disc herniation were tested before surgery and 4 weeks after surgery. The protocol comprised an isometric endurance test (modified Sørensen's test) with concomitant measures of electromyography, and Borg ratings of pain and fatigue. To measure activity, participation, self-efficacy and health, the patients also filled in questionnaires. Results showed a post-operatively significant improvement in lumbar muscle fatigue expressed as a flatter L5 slope for the men. No significant improvement was found for endurance times or for Borg ratings. Endurance time correlated with questionnaire answers on physical activity, the Roland-Morris, the Oswestry, self-efficacy and some items of the SF-36 with correlation coefficients ranging from 0.52 to 0.91. The L5 slope correlated with the Roland-Morris, the Oswestry and some items of the SF-36 only in women with correlation coefficients between 0.53 and 0.77. We conclude that the effects of surgery reduced muscle fatigue for the men. There is an association between muscle fatigue and endurance with activity limitations, participation restrictions, self-efficacy and health in patients undergoing surgery for lumbar disc herniation.