Simple prediction method of lumbar lordosis for planning of lumbar corrective surgery: radiological analysis in a Korean population

Tethered cord secondary to focal nondisjunction of the primary neural tube: experience from a Singapore children's hospital

PURPOSE

Tethered cord due to focal nondisjunction of primary neuralisation (FNPN) is a rare form of spinal dysraphism. We present our institutional experience in managing children diagnosed with FNPN.

MATERIALS AND METHODS

This is a single institution, retrospective study approved by the hospital ethics board. Patients below 18 years of age diagnosed with CDS, LDM or their mixed lesions, and subsequently underwent intervention by the Neurosurgical Service, KK Women's and Children's Hospital, are included.

RESULTS

From 2001 to 2021, 16 FNPN patients (50% males) were recruited. Eight of them had CDS (50.0%), seven had LDM (43.8%), and one patient had a mixed CDS and LDM lesion (6.2%). The average duration of follow up was 5.7 years and the mean age of surgery was 6 months old. Thirteen patients underwent prophylactic intent surgery (81.2%) and three had therapeutic intent surgery (18.8%). All patients did not have new neurological deficit or required repeat surgery for cord retethering. We observed that detethering surgery performed at or less than three months old was associated with having a wound infection (p = .022).

CONCLUSIONS

Our study reports that early recognition and timely intervention are mainstays of management for FNPN. We advocate a multi-disciplinary approach for good outcomes.

Proximal Junctional Failure after Corrective Surgery: Focusing on Elderly Patients with Severe Sagittal Imbalance

Background

Previous reports with proximal junctional failure (PJF) included relatively young patients or deformity without sagittal imbalance. The present study focused on the two well-known risk factors for PJF, old age and severe sagittal imbalance. With these high-risk patients, the present study aimed to identify a strategy that could prevent PJF and to investigate whether the degree of correction would really affect the PJF occurrence.

Methods

Patients who were ≥ 60 years of age and underwent long fusion (≥ 4) to the sacrum for severe sagittal imbalance (defined as pelvic incidence minus lumbar lordosis [PI-LL] ≥ 30°) were included. PJF was defined as a vertebral fracture at the uppermost instrumented vertebra (UIV) or UIV+1, failure of UIV fixation, myelopathy, or any need for proximal extension of fusion. Presumed risk factors were compared between the patients with and without PJF.

Results

Total 146 patients (mean age, 68.4 years) with preoperative mean PI-LL of 46.8° were included. PJF developed in 39 patients (26.7%) at a mean of 18.1 months after surgery. Multivariate analysis showed that osteoporosis (odds ratio [OR], 2.812; p = 0.019) and UIV located below T10 (OR, 3.773; p = 0.010) were significant risk factors for developing PJF. However, the degree of correction did not affect PJF occurrence.

Conclusions

The present study indicates that osteoporosis should be well corrected preoperatively and extending the fusion above T10 should be considered for severe imbalance in old patients. However, the amount of correction was not associated with PJF development.

Lumbar Lordosis Distribution in Asymptomatic Adult Volunteers: A Systematic Review

Background

Restoring lumbar lordosis is important for adult spinal deformity surgery. Several reports have suggested that lumbar lordosis distribution has a significant impact on the outcome of surgery, including lumbar distribution index (LDI), proximal lumbar lordosis (PLL), and distal lumbar lordosis (DLL). The features of lumbar lordosis distribution are inconclusive in asymptomatic adults.

Questions/Purposes

We sought to evaluate the variation of lumbar lordosis distribution (LDI, PLL, and DLL) and to identify associated factors in asymptomatic adult volunteers.

Methods

We performed a systematic review of the Embase and Medline databases to identify studies in asymptomatic adult volunteers to evaluate lumbar lordosis distribution including LDI, PLL, and DLL.

Results

Twelve articles met eligibility criteria and were included in our review. The respective pooled estimates of mean and variance, respectively, were 65.10% (95% confidence interval [CI]: 62.61-67.58) and 13.70% in LDI, 16.51° (95% CI: 5.54-27.49) and 11.46° in PLL, and 35.47° (95% CI: 32.79-38.18) and 9.10° in DLL. Lumbar lordosis distribution was associated with race, age, sex, body mass index, pelvic incidence, and Roussouly classification.

Conclusions

This systematic review found that despite a wide variation in LDI and PLL, DLL is maintained in a narrower range in asymptomatic adult volunteers, especially in white populations. Distal lumbar lordosis may be a more reliable radiographic parameter to restore the lumbar lordosis distribution in preoperative planning.

An Analysis of Whether a New Formula Can Predict Proximal Junctional Failure in Adult Spinal Deformity Patients with Global Kyphosis

OBJECTIVE

A new formula containing terms for age and sagittal curvature reported by the International Spine Study Group is ideal lumbar lordosis (iLL) = pelvic incidence - 0.3 thoracic kyphosis - 0.5Age + 10. However, there are no reports of whether proximal junctional failure (PJF) can be predicted using this formula. We assessed the utility of this formula in PJF in patients with adult spinal deformity with global kyphosis using the Roussouly classification.

METHODS

Forty-four patients with adult spinal deformity global kyphosis (mean age 70.0 years) who underwent multiple levels of lateral lumbar interbody fusion combined with posterior instrumentation were included. Patients were divided into 2 groups: PJF and non-PJF. Demographic, surgical, and radiological parameters were compared. The iLL was calculated according to the new formula, and spinal parameters were compared preoperatively, immediately after, and at the final follow-up.

RESULTS

PJF occurred in 11 of 44 (25.0%) patients. Patients with PJF had a large preoperative and postoperative TK, but there was no statistically significant difference in iLL between PJF and non-PJF patients (33.4° vs. 30.2°, P = 0.357). In addition, there was no statistically significant difference in LL and iLL changes (ΔiLL) immediately after surgery (19.0° vs. 23.4°, P = 0.379). Furthermore, there was no correlation between ΔiLL immediately after surgery and at the final follow-up and the proximal junctional angle at the final follow-up.

CONCLUSIONS

The results of ΔiLL suggest that overcorrection needs to be addressed but that this new formula, including age adjustment, may not predict PJF.

Predicting the ideal apex of lumbar lordosis based on individual pelvic incidence and inflection point in asymptomatic adults

Objective

The main aim of this study was to comprehensively explore the relationship among pelvic incidence (PI), inflection point (IP), and apex of lumbar lordosis (LLA), and establish a predictive formula for LLA based on individual PI and IP in asymptomatic Chinese adults.

Methods

A total of 385 asymptomatic adults with average age 38.3 ± 11.9 years (range 20–73 years) were recruited between November 2020 and October 2021. Full-spine, standing x-rays were then obtained from each participant. Next, the following sagittal parameters were measured: PI, IP, LLA, the horizontal offset between the plumb line of the lumbar apex and that of the posterosuperior corner of S1 (LASO), the upper lumbar lordosis (ULL) and lower lumbar lordosis (LLL), lumbar lordosis (LL), and thoracic kyphosis (TK). Moreover, the association among PI, IP, and the other sagittal parameters was evaluated, followed by linear regression analyses. A P-value of <0.05 was considered statistically significant.

Results

PI showed statistically significant correlations with LLA (r_s = −0.629; P < 0.01), LASO (r_s = 0.537; P < 0.01), LLL (r_s = 0.788; P < 0.01), and LL (r_s = 0.663; P < 0.01). On the other hand, IP also showed statistically significant correlations with LLA (r_s = 0.671; P < 0.01), LASO (r_s = −0.493; P < 0.01), LLL (r_s = −0.402; P < 0.01), and LL (r_s = −0.283; P < 0.01). The corresponding predictive formulae were displayed as follows: LLA = −0.03 * PI + 0.23 * IP + 14.45 (R²= 0.669); LASO = 0.38 * PI−2.09 * IP + 53.62 (R²= 0.460); and LLL = 0.58 * PI−0.88 * IP + 18.86 (R²= 0.659).

Conclusion

The specific lumbar shape should be modulated by pelvic morphology and IP level. In addition, we established predictive formulae for ideal sagittal lumbar profile based on individual PI and IP, with the overarching goal of helping surgeons to better comprehend the regulatory mechanisms of the individual sagittal lumbar alignment, and design a precise and personalized corrective plan.

Restoring Theoretically Optimal Lumbar Lordosis Deduced from Pelvic Incidence and Thoracic Kyphosis has Advantages to Decrease the Risk of Postoperative Mechanical Complications in Adult Spinal Deformity

Objective

To establish a regression formula for LL based on individual PI and TK in asymptomatic population aged over 50 years and evaluate its predictive power for the occurrence of postoperative mechanical complications in patients with adult spinal deformity (ASD).

Methods

A total of 178 asymptomatic adults were recruited for the study. The association between LL and PI, LL and TK, was investigated to establish a predictive formula for ideal LL based on PI and TK. Additionally, 93 ASD patients undergoing posterior correction surgery were retrospectively analyzed. The absolute value of the gap between postoperative actual LL and theoretical LL was defined as ΔLL. Patients were classified into two groups depending on the presence or absence of mechanical complications. The demographic and radiological data of patients were compared between the two groups.

Results

A significant association was found between LL and PI (r = 0.599, P &lt; 0.001), LL and TK (r = 0.523, P &lt; 0.001). A novel formula was developed as follows: LL = 0.7*PI + 0.4*TK + 1 (R2 = 0.524). In the validation cohort, 29 patients developed mechanical complications. Postoperative ΔLL (12.5 ± 7.6° vs. 7.0 ± 5.4°, P = 0.001) significantly increased the incidence of mechanical complications. The most appropriate threshold of ΔLL for predicting mechanical complications was 9.8°. For patients whose ΔLL were &lt;9.8° and &gt;9.8°, the incidence of mechanical complications was 19.4% and 54.8%, respectively.

Conclusion

Ideal lumbar lordosis should be matched for PI and TK. The developed prediction formula for LL based on PI and TK in asymptomatic adults may help surgeons to understand the mechanisms of lumbar alignment generation and predict occurrence of mechanical complications after ASD surgery.

An Anatomical Clue for Minimizing Iliac Vein Injury During the Anterolateral Approach at L5-S1 Level: A Cadaveric Study

Objective

The injury to the common iliac vein (CIV) seems to be the most important concern during the anterior approach to the spine at L5–S1 level. We investigated the anatomy of the L5–S1 vertebral structures related to the CIV through a cadaveric study to find an anatomical clue for safe dissection of CIV.

Methods

Ten cadavers were prepared for this study. After removing the peritoneum and the presacral fascia, the section from the lower part of the L5 to the upper part of the S1 vertebral body was removed with the CIV attached. After decalcification, 2 sections in the vertical and horizontal directions were made for histological study.

Results

An adipose tissue layer was present between the intervertebral disc and CIV. The adipose tissue layer in 6 cadavers was thin, and in 3 of these cadavers, the CIV was attached to the vertebral body and the disc. In the other 4 cadavers, the CIV was clearly separated from the vertebral body and the disc by the intervening adipose tissue layer (IATL). Under the microscope, a thin layer surrounding the anterior longitudinal ligament, periosteum, and disc was observed, and we named this structure the ‘perivertebral membrane.’ The perivertebral membrane was attached to the CIV when there was no IATL, but a potential space was detected under the membrane.

Conclusion

There was a thin membrane, perivertebral membrane, between the CIV and L5–S1 disc. In cases with CIV adhesion to the disc due to the absence of IATL, the CIV may be mobilized indirectly through the perivertebral membrane.

Optimal Lumbar Lordosis Correction for Adult Spinal Deformity with Severe Sagittal Imbalance in Patients Over Age 60: Role of Pelvic Tilt and Pelvic Tilt Ratio

STUDY DESIGN

A retrospective study.

OBJECTIVES

The purpose of this study was to evaluate optimal and ideal target values of the spine balance correction in elderly patients with adult spinal deformity who were over the age of 60 years.

SUMMARY OF BACKGROUND DATA

The target values of the Scoliosis Research Society -Schwab classification to obtain satisfactory alignment and favorable outcomes are used in many spinal reconstruction surgeries. However, uniformly applying the Scoliosis Research Society-Schwab classification to all elderly patients aged 60 years or older showing sagittal malalignment may lead to several inconsistencies.

METHODS

This study included 121 patients (average age 70.5 yr and a minimum 2-yr follow-up) with adult spinal deformity who underwent long-segment fusion from T10 to sacrum. We used Pearson's correlation coefficient to analyze the relationship between clinical and radiographic parameters, and multilinear regression analysis and multivariate logistic regression model (backward elimination method) were conducted using the correlation factors of postoperative (Post) and last follow-up (Last) sagittal vertical axis to find the risk factors of Post sagittal imbalance.

RESULTS

Logistic regression analysis with the correlation factors of Post and Last sagittal vertical axis led to risk factors of Post sagittal imbalance, and after confirming the significance of each path, it was confirmed that the effects of pelvic incidence (PI)- lumbar lordosis (LL) and Post pelvic tilt ratio (PTr) were valid (P < 0.05). After using ROC curve, target value of PI-LL was 1.33, and that of PTr was 25.95%.

CONCLUSION

Through our study, the risk factors of Post sagittal imbalance were the Post value of PI-LL and that of PTr, and target value of PI-LL was <1.33 and that of PTr was <25.95%. These target values can be effective guidelines for spine surgeons who perform spine reconstruction surgeries for elderly patients with a pure sagittal imbalance based on Schwab's formula.Level of Evidence: 4.

Pelvic and sacral morphology and their correlation with pelvic incidence, lumbar lordosis, and lumbar alignment changes between standing and sitting postures

STUDY DESIGN

Retrospective Cross-Sectional Radiographic Study.

OBJECTIVE

This study aims to describe novel radiographic markers of sacropelvic morphology to further define the static and dynamic relationship between the pelvis and the spine, via the analysis of two postures - standing and sitting.

SUMMARY OF BACKGROUND DATA

There is increasing evidence underlining the importance of spinopelvic radiographic parameters in the holistic management of sagittal spinal deformity given the close relationship between pelvic morphology and spinal profile.

METHODS

This is a retrospective radiographic study of patients who presented with the first episode of isolated mechanical, low back pain of fewer than 3 months' duration. All patients underwent whole spine radiographs using EOS technology in both standing and relaxed sitting postures. Six novel distance measurements (H1, H2, H3, V1, V2, DD) to determine pelvic dimensions, and 3 novel angles (A, B, C) to determine sacral morphology were described.

RESULTS

A total of 64 males (58.2%) and 46 females (41.8%) with a mean age of 42.8 ± 18.6 (range:17-81) years old was studied. Between standing and relaxed sitting postures, differences were observed in all sagittal radiographic parameters. Multivariate analysis showed that standing LL< 50⁰ (p = 0.008), standing V1 > 13 cm(p = 0.040), and angle B> 80⁰(p = 0.002) are predictive of PI< 5⁰⁰, standing TK< 30⁰ (p = 0.003) and PI< 50⁰ (p = ⁰.006) are predictive of LL< 5⁰⁰, and standing PT< 17⁰(p = 0.034), standing H3 ≥ 4 cm (p = 0.030), standing angle C< 42⁰ (p = 0.003), sitting SS≥ 6⁰ (p = ⁰.002), and sitting PT < 45⁰ (p = 0.013) are predictive of change in LL below mean difference of 42⁰ between standing and relaxed sitting.

CONCLUSIONS

Apart from the known correlation between TK, LL and PI, low PI was found to be associated with a tall pelvis and a straight sacrum (angle B). Association between a small coccygeal inclination angle (angle C) and smaller change in LL between standing and relaxed sitting may have clinical relevance.

Reproducibility and Accuracy of Pelvic Tilt in Predicting the Difference Between Pelvic Incidence and Lumbar Lordosis Value

OBJECTIVE

We investigated the pelvic morphologic factors that determine the degree of pelvic incidence (PI)-lumbar lordosis (LL) mismatch.

METHODS

Overall, 306 patients were included. The regional and global sagittal parameters were measured. Linear regression analyses were performed for 4 pelvic parameters and PI-LL mismatch. E1 and E2 were defined as linear regression equations between pelvic tilt (PT) and PI-LL mismatch and PI and PI-LL mismatch, respectively. The patients were categorized by cluster analysis using the hierarchal method for the 4 pelvic parameters.

RESULTS

E1 and E2 showed statistical significance; however, the coefficient of determination of E1 was higher than that of E2 (R² = 0.675 vs. 0.238; P < 0.01). Sex, LL, E1, and E2 showed significant differences in the regional parameters. The T1 pelvic angle (TPA), spinosacral angle (SSA), and incidence angle of inflection points (IAIPs) showed significant differences in global parameters (P < 0.01). The IAIPs and TPA were low in the anteverted pelvis group and high in the retroverted pelvis group (P < 0.001). The SSA was low in the small pelvis group and high in the large pelvis group (P < 0.001). The proportion of women in the large pelvis group (93%) was significantly higher than that in the other groups (P < 0.01).

CONCLUSIONS

The individual differences between the PI and LL values can be more accurately determined using the individual PT, and the optimal PT amount will differ depending on the pelvis shape. The increase in the TPA and IAIPs corresponded to the PT, and the SSA increased in accordance with the pelvic size.

Long-term benefits of appropriately corrected sagittal alignment in reconstructive surgery for adult spinal deformity: evaluation of clinical outcomes and mechanical failures

OBJECTIVE

It has been well documented that optimal sagittal alignment is highly correlated with good clinical outcomes in adult spinal deformity (ASD) surgery. However, it remains to be determined whether the clinical benefit of appropriately corrected sagittal alignment can be maintained in the long term. Therefore, the aim of this study was to investigate whether appropriately corrected sagittal alignment continues to offer benefits over time with regard to clinical outcomes and mechanical failure.

METHODS

Patients older than 50 years who underwent ≥ 4-level fusion for ASD and were followed up for ≥ 5 years were included in this study. Appropriateness of sagittal alignment correction was defined as pelvic incidence minus lumbar lordosis ≤ 10°, pelvic tilt ≤ 25°, and sagittal vertical axis ≤ 50 mm. Two groups were created based on this appropriateness: group A (appropriate) and group IA (inappropriate). Clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry Disability Index (ODI), and Scoliosis Research Society Outcomes Questionnaire-22 (SRS-22). The development of mechanical failures, such as rod fracture and proximal junctional kyphosis (PJK), was compared between the two groups.

RESULTS

The study included 90 patients with a follow-up duration of 90.3 months. There were 30 patients in group A and 60 patients in group IA. The clinical outcomes at 2 years were significantly better in group A than in group IA in terms of the VAS scores, ODI scores, and all domains of SRS-22. At the final follow-up visit, back VAS and ODI scores were still lower in group A than they were in group IA, but the VAS score for leg pain did not differ between the groups. The SRS-22 score at the final follow-up showed that only the pain and self-image/appearance domains and the total sum were significantly higher in group A than in group IA. The incidence of rod fracture and PJK did not differ between the two groups. The rate of revision surgery for rod fracture or PJK was also similar between the two groups.

CONCLUSIONS

The clinical benefits from appropriate correction of sagittal alignment continued for a mean of 90.3 months. However, the intergroup difference in clinical outcomes between groups A and IA decreased over time. The development of rod fracture or PJK was not affected by the appropriateness of sagittal alignment.

Patterns of coronal and sagittal deformities in adolescent idiopathic scoliosis

BACKGROUND

Thoracic scoliosis has been shown to be associated with hypokyphosis in adolescent idiopathic scoliosis (AIS). However, the relationship of sagittal spino-pelvic parameters with different coronal curve patterns and their influence on patient-perceived quality of life is unknown. This study aims to determine the association between coronal and sagittal malalignment in patients with AIS and to determine their effects on SRS-22r scores.

METHODS

A cross-sectional study was conducted on 1054 consecutive patients with AIS. The coronal Cobb angle, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), PI-LL mismatch (PI-LL), pelvic tilt (PT), and sacral slope (SS) were measured on standing radiographs. The coronal Cobb angle (mild: 10-20°; moderate: > 20-40°; severe: > 40°) and PI (low: < 35°; average: 35-50°; high: > 50°) were divided into 3 sub-groups for comparison. Relationship between coronal curve magnitudes and sagittal parameters was studied as was their association with SRS-22r scores.

RESULTS

Low PI had smaller SS (30.1 ± 8.3° vs 44.8 ± 7.7°; p < 0.001), PT (- 0.3 ± 8.1° vs 14.4 ± 7.5°; p < 0.001), and LL (42.0 ± 13.2° vs 55.1 ± 10.6°; p < 0.001), negative PI-LL mismatch (- 12.1 ± 13.1° vs 4.1 ± 10.5°; p < 0.001) as compared to large PI. There were no significant relationships with PI and TK (p = 0.905) or curve magnitude (p = 0.431). No differences in sagittal parameters were observed for mild, moderate or severe coronal Cobb angles. SRS-22r scores only correlated with coronal Cobb angle and larger Cobb angles were negatively correlated with the function, appearance and pain domains.

CONCLUSIONS

The sagittal profile for AIS is associated with the pelvic parameters especially PI but not with the coronal curve pattern. All patients have a similar TK regardless of coronal curve type. However, it appears that the coronal deformity is a greater influence on quality of life outcomes especially those > 40°.

Spino-Pelvic Thresholds for Prevention of Proximal Junctional Kyphosis Following Combined Anterior Column Realignment and Short Posterior Spinal Fusion in Degenerative Lumbar Kyphosis

Objective

To analyze ideal indication for combined anterior column realignment (ACR) with short posterior spinal fusion (PSF) and posterior column osteotomy (PCO) for preventing proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) patients with lower lumbar kyphosis and compensatory thoracolumbar lordosis.

Methods

A retrospective study was conducted. This study included 27 ASD patients (average age of 66.6 years; one male and 26 females) with lower lumbar kyphosis and compensated thoracolumbar lordosis who underwent short PSF with PCO following ACR from 2006 to 2010. The minimum follow‐up period was 5 years. The patients were divided into two groups based on the sagittal vertical axis (SVA) of the last follow‐up radiographs, and a comparative analysis was performed evaluating spino‐pelvic parameters and clinical outcomes including the Oswestry Disability Index (ODI), Visual Analog Scale (VAS), and complications.

Results

The mean follow‐up time of included patients was 109.7 months, and the mean number of fused segments was 3.7. The uppermost instrumented vertebra was L₂ in 18 patients or L₃ in nine patients, and lowermost instrumented vertebra was sacrum in all patients. The mean lumbar lordosis (LL) values in the optimal SVA and suboptimal SVA groups were 4.4° and 4.2° preoperatively (P = 0.639), −48.1° and −35° postoperatively (P = 0.007), and −45.2° and −20.7° at the last follow‐up (P < 0.05). Overcorrection was seen in seven patients in the optimal SVA group, whereas all of the patients of the suboptimal SVA group were in the category of undercorrection (P = 0.021). Pelvic incidence (PI) of optimal SVA group (<50 mm, n = 16) and suboptimal SVA group (≥50 mm, n = 11) was 44.1° and 53.8° (P = 0.009). The prevalence of PJK was significantly higher in the suboptimal SVA group (P = 0.008), and last follow‐up VAS for back pain (P < 0.05), and postoperative and last follow‐up ODI (P = 0.002 and P < 0.05) were statistically larger for the suboptimal group than the optimal group.

Conclusions

Combined ACR with short PSF and PCO could effectively prevent sagittal decompensation of PJK and help achieve sagittal balance in the treatment of ASD patients with lower lumbar kyphosis, compensatory thoracolumbar lordosis, and especially low PI (<50°).

Proximal Junctional Kyphosis in Degenerative Sagittal Deformity After Under- and Overcorrection of Lumbar Lordosis: Does Overcorrection of Lumbar Lordosis Instigate PJK?

STUDY DESIGN

Retrospective study.

OBJECTIVE

To analyze proximal junctional kyphosis (PJK) occurrence and surgical outcomes according to degree of lumbar lordosis (LL) correction relative to pelvic incidence (PI). In addition, risk factors of PJK including LL and sagittal vertical axis (SVA) correction were investigated.

SUMMARY OF BACKGROUND DATA

PJK is a common complication after adult spinal deformity surgery, and many factors are known to be associated with PJK. However, the effect of degree of LL correction on PJK occurrence is not fully understood.

METHODS

Eighty-three degenerative sagittal imbalance patients treated with deformity correction and long instrumented fusion to the sacrum with a minimum follow-up of 2 years were studied. Patients were divided into three groups according to their postoperative LL angle relative to PI using the SRS-Schwab classification: Group A (undercorrection, PI-LL> 10°), Group B (ideal correction, -10°

RESULTS

Overall PJK prevalence was 36.1% (30/83), and ratio of optimal SVA at postoperative and last follow-up were significantly higher in Group C (P < 0.001, P < 0.001). Nevertheless, there was no significant difference in PJK prevalence among three groups (40% vs. 37.5% vs. 34.1%; P = 0.907). Group C had better clinical outcomes (last follow-up ODI, VAS of LBP) than Group A (10.0 vs. 18.4; P < 0.001 and 1.5 vs. 4.0; P < 0.001). The increases in LL or SVA correction degree were not associated with PJK occurrence (P = 0.304, P = 0.201).

CONCLUSION

Overcorrection showed good surgical outcomes without increasing PJK prevalence. Degrees of LL and SVA correction do not act as risk factors for PJK. Therefore, in adult spinal deformity patients, LL correction greater than PI may be a good choice that can result in better clinical outcomes without increasing risk of PJK.

LEVEL OF EVIDENCE

4.

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MESH Headings

• Adult
• Aged
• Animals
• Female
• Humans
• Kyphosis/diagnostic imaging
• Kyphosis/etiology
• Lordosis/diagnostic imaging
• Lordosis/surgery
• Lumbar Vertebrae/diagnostic imaging
• Lumbar Vertebrae/surgery
• Male
• Middle Aged
• Neurodegenerative Diseases/diagnostic imaging
• Neurodegenerative Diseases/etiology
• Neurosurgical Procedures/adverse effects
• Neurosurgical Procedures/trends
• Retrospective Studies
• Risk Factors

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Grants Collapse

Affiliation(s)

Sang-Kyu Im Department of Orthopedic Surgery, Graduate School, College of Medicine, Kyung Hee University, Seoul, Korea
Jung-Hee Lee
Kyung-Chung Kang
Sung Joon Shin
Ki Young Lee
Jong Jun Park
Man Ho Kim

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Estimation of the ideal correction of lumbar lordosis to prevent reoperation for symptomatic adjacent segment disease after lumbar fusion in older people

Background

Symptomatic adjacent segment disease (ASDis) is a major complication following spinal fusion. Sagittal spinopelvic imbalance may contribute to the development of ASDis. However, the exact ideal correction of lumbar lordosis (LL) is unknown for different ages of people to prevent ASDis. The purpose of this study was to estimate the ideal correction of LL required to prevent symptomatic ASDis requiring revision surgery in patients of various ages, and to determine the radiographic risk factors for ASDis.

Methods

468 patients who underwent lumbar fusion between January 2014 and December 2016, were enrolled in the present study. The patients were classified into the ASDis and N-ASD group. These two matched groups were compared regarding surgery-related factors and radiographic features. Multivariate logistic regression analysis was used to evaluate the risk factors for ASDis.

Results

Sixty-two patients (13.25%) underwent reoperation for ASDis during a mean follow-up duration of 38.07 months. Receiver operating characteristic curve analysis showed that the postoperative LL - preoperative LL (△LL) cutoff value was 11.7°for the development of ASDis. Logistic regression analysis revealed that the risk factors for symptomatic ASDis were a smaller LL angle, △LL > 12°, and PI-LL > 10° (p <  0.05). For patients > 60 years, the incidence of ASDis was higher in patients with a LL correction of ≥10° and a lumbar-pelvic mismatch (PI-LL) of > 20°.

Conclusions

The significant predictors of the occurrence of ASDis were a smaller LL angle, △LL > 12°, and PI-LL > 10°. However, in patients older than 60 years, the incidence of ASDis after lumbar fusion was higher in those with a LL correction of ≥10° and PI-LL of > 20°. More attention should be paid to patient age and the angle of correction of LL before lumbar fusion.

Differences in lumbar segment angle among Roussouly types of global sagittal alignment in asymptomatic adult subjects

STUDY DESIGN

A radiological study.

OBJECTIVES

To examine lumbar segment angle according to the Roussouly type of global sagittal alignment and to determine the reference disc angles in minimally invasive surgery (MIS) for adult spinal deformity. Optimal restoration of lumbar lordosis (LL) in adult spinal deformity surgery includes achieving the ideal shape of LL as well as the amount of LL. However, the distribution of lumbar segment angles by the Roussouly type has yet to be elucidated.

METHODS

Forty sets of whole spine lateral radiographs covering the four Roussouly types (N = 160) were obtained from a database of asymptomatic adult subjects. Global and spinopelvic parameters were measured. Disc and vertebral angles at each lumbar level were compared among the Roussouly types.

RESULTS

There were 75 (46.9%) men with a mean age of 32.8 ± 8.9 years among the total of 160 study subjects. A significant difference was found in spino-sacral angle, sacral slope, pelvic incidence, LL, and lower arc of LL (L4S1) among the Roussouly types (all P < 0.001). The ratio of the lower arc of LL (L4S1) to LL was 83.4% in Roussouly type 1, 65.2% in type 2, 64.7% in type 3, and 61.5% in type 4. The disc angles at the L1-2 and L2-3 levels in Roussouly type 1 were significantly smaller than in the other types. The disc angle at the L5-S1 level in Roussouly type 1 was significantly larger than that in type 2. Roussouly type 4 had a larger disc angle at the L2-3 and L4-5 levels than types 1 and 2.

CONCLUSIONS

The results of this study showed that the disc angle distribution differs among Roussouly types. The configuration of LL as well as the amount of LL should be considered in adult spinal deformity surgery.

LEVEL OF EVIDENCE

Level IV.

The influence of spinopelvic morphologies on sagittal spinal alignment: an analysis of incidence angle of inflection points

PURPOSE

To elucidate whether specific spinopelvic morphologies affect the subsequent spinal sagittal alignments and determine the alignment patterns.

METHODS

Whole-spine standing radiographs of 244 patients were analyzed. Sagittal alignment parameters were compared according to the three types of pelvic version: anteverted pelvis (AP), neutral pelvis, and retroverted pelvis (RP), grouped per the amount of pelvic tilt (PT) and the ratio of sacral slope to pelvic incidence (PI). Incidence angles of inflection points (IAIPs) were defined as the angle between a line from the center of the femoral heads through the midpoint of the sacral superior endplate and a line perpendicular to each L1, T1 superior endplate, C2 inferior endplate, and the C1 ring, respectively.

RESULTS

C1 incidence equaled to the geometrical sum from the pelvis to the C1 vertebra; it also equaled the sum of the C1 slope and PT (p < 0.001). Moving from the AP group to the RP group, there were progressive increases in PT, PI, and IAIPs and decreases in LL, and SS/PI (p < 0.001). Negative correlation was observed between the pelvic anteversion and the IAIPs, and a significant positive correlation was observed between the pelvic retroversion and the IAIPs.

CONCLUSION

IAIPs are novel PI-relevant radiographic parameters reflecting the relationship between the pelvis and the spinal alignment. An anteverted pelvis requires more lumbar lordosis than pelvic incidence and aligns with low IAIPs, and a retroverted pelvis requires less lumbar lordosis than pelvic incidence and aligns with high IAIPs. These slides can be retrieved under Electronic Supplementary Material.

The importance of sagittal balance in adult scoliosis surgery

Adult spinal deformity is an important health issue worldwide with our aging population. Understanding ideal sagittal alignment parameters is crucial for planning reconstructive surgery. Despite its variability, sagittal spinopelvic parameters are well recognized as the most crucial factor in predicting postoperative outcomes and risks of revision surgery. Thus, understanding the fundamental concepts of spinopelvic harmony is of utmost importance because they provide useful recommendations for what should be achieved during surgery. The main pathology in degenerative spine disease is the loss of lumbar lordosis (LL), which contributes to lower back pain. The loss of LL may occur as a result of natural history with spinal degeneration or by previous lumbar spine fusion. With adult spinal deformity, understanding the compensatory mechanisms available to patients is important for determining the timing of surgery. The main compensatory mechanisms patients adopt to maintain an upright posture include decreased sacral slope (SS), increased pelvic tilt (PT), decreased thoracic kyphosis (TK). Failure of these compensatory mechanisms leads to recruitment of the lower limbs with flexed hips and knees. At this stage, the patient is decompensated and result in positive sagittal alignment. This sagittal imbalance can be easily measured by the sagittal vertical axis (SVA) and is associated with worse patient-perceived outcome scores. These sagittal parameters also indicate whether surgical reconstruction is required and provides the necessary alignment goals. Depending on the value of pelvic incidence (PI), there are different LL goals. High PI has increased capacity for pelvic retroversion but requires greater lordosis correction. Proper restoration of the LL according to the PI will reduce pelvic retroversion reflected by reduced PT. Without adherence to these surgical goals, complications such as proximal junctional kyphosis (PJK) may occur. It is imperative to restore normal spinopelvic balance to maximize functional outcomes, reduce pain, and avoid complications.

Rod Fracture Causing Relief of Back Pain That Developed After Adult Lumbar Degenerative Flat-Back Correction Surgery: A Case Report

A 73-year-old woman underwent deformity correction surgery (anterior lumbar interbody fusion of L2-L3-L4-L5-S1, pedicle subtraction osteotomy at L4, and posterior screw fixation from T10 to the pelvis) due to lumbar degenerative flat-back. Following the operation, the patient experienced pain in her back and buttocks, for which she regularly took medications. She reported frequently feeling a heavy and stretched sensation of pain after the operation in those areas, which made her regret undergoing the operation. However, at 33 months postoperatively, she reported that one day, while getting up from a chair, she felt a crack in her back, which was followed by an improvement in her back and buttock pain; thereafter, she stopped taking pain medications. Follow-up radiography revealed a bilateral rod fracture at the L4–5 level on the right side and at the L3–4 level on the left side. The overall pelvic parameters, except pelvic incidence, slightly changed after the rod fracture. Therefore, the broken rod was replaced and another rod was added to the broken rod area; however, the changed pelvic parameters were not corrected further during the reoperation. Following the reoperation, the patient showed improvements and she no longer required pain medication.

Relationship Between Lumbar Lordosis and Pelvic Incidence in the Adolescent Patient: Normal Cohort Analysis and Literature Comparison

STUDY DESIGN

Retrospective review; literature comparison.

OBJECTIVES

To review the literature on the relationship between lumbar lordosis (LL) and pelvic incidence (PI) and evaluate this relationship in asymptomatic adolescents while testing the validity of previously reported adult correlation models between LL and PI in an adolescent population.

SUMMARY OF BACKGROUND DATA

Accurate understanding of the normal spinopelvic relationship is critical when considering surgical fusion of the lumbar spine. Many studies have reported relationships between pelvic measurements and LL in adult populations, but data in pediatric populations is lacking.

METHODS

A literature search was performed to identify previously reported relationships between pelvic parameters and LL in adults and pediatric patients. A cohort of 125 asymptomatic adolescent patients evaluated at our institution was evenly split into two cohorts for model development and validation. Linear regression between LL and PI was performed. The resultant regression model was tested in the validation cohort along with previously reported formulae with LL as a function of PI. Mean absolute error (MAE) was calculated and compared between prior models and the newly developed adolescent model using analysis of variance and post-hoc testing.

RESULTS

In our adolescent cohort (mean age: 13 ± 2), there was a strong correlation between PI and LL (r = 0.53). Regression analysis in the development cohort produced the following predictive model: LL = 0.66(PI) + 24.2. Testing in the validation cohort revealed a good correlation between predicted and actual LL (r = 0.51) and an MAE of 8.3. All but three previously reported models functioned with similar accuracy in the adolescent population, with only two methods having an MAE over 10.

CONCLUSIONS

The majority of previously published formulae for predicting LL as a function of PI developed in adults can be extrapolated to adolescent populations. These relationships are important in understanding how to surgically restore the sagittal alignment in adolescents with spinal deformity.

LEVEL OF EVIDENCE

Level IV.

Effect of age and sex on lumbar lordosis and the range of motion. A systematic review and meta-analysis

Lumbar lordosis (LL) and the range of motion (RoM) are important physiological measurements when initiating any diagnosis and treatment plan for patients with low back pain. Numerous studies reported differences in LL and the RoM due to age and sex. However, these findings remain contradictory. A systematic review and meta-analysis were performed to synthesize mean values and the differences in LL and the RoM because of age and sex. The quality assessment tool for quantitative studies was applied to assess the methodological quality of the studies included. We identified 2372 papers through electronic (2309) and physical (63) searches. We assessed 218 full-text studies reporting measurements of LL or the RoM. In total, 65 studies were included, and a normative database for LL and the RoM is provided as supplementary material. Among these, 11 were included in the meta-analysis. LL and the RoM displayed non-monotonic variations with significant age and sex differences. Young females showed a significantly greater LL and the range of extension (RoE), whereas young males exhibited a greater range of flexion (RoF). Sex differences in the range of lateral bending (RoLB) were small but were significant for the axial rotation (RoAR). For the RoF, RoE and RoLB, differences because of age were significant among most of the age groups in both sexes, whereas for the RoAR, differences were significant only between the 20s vs the 30s-40s (males) and 40s vs 50s (females). Significant differences because of age/sex were identified. However, the age-dependent reduction in LL and the RoM was non-monotonic and differed in both sexes. These findings will help to better distinguish between functional deficits caused by spinal disorders and natural factors/conditions related to age and sex.

Recurrent Hip Dislocation Following Total Hip Arthroplasty: Treatment with Sagittal Spinal Deformity Correction: A Case Report

CASE

A 63-year-old woman with lumbar degenerative kyphosis who had undergone total hip arthroplasty 34 months previously presented after having multiple episodes of anterior hip dislocation; evaluation also revealed progressive osteoarthritis in the contralateral hip joint. The patient was managed with sagittal correction with pedicle subtraction osteotomy, which resulted in optimal positioning of the acetabular component and an upright posture. The patient had had no additional dislocation events in the involved hip and had reduced pain in the contralateral hip at the time of the 2-year follow-up.

CONCLUSION

It is important to evaluate and address preexisting sagittal imbalance before performing total hip arthroplasty. However, for patients with neglected sagittal imbalance resulting in recurrent hip dislocation after total hip arthroplasty, sagittal deformity correction may be beneficial.

Predictors for Postoperative Loss of Lumbar Lordosis After Long Fusions Arthrodesis in Patients with Adult Scoliosis

Background

Loss of lumbar lordosis (LL) is closely related to clinical symptoms and operative complications, however, few studies have identified its predictors. The purpose of our study was to identify the predictors for loss of LL in patients with adult scoliosis and provided evidence for surgical decision-making.

Material/Methods

There were 69 patients with adult scoliosis who underwent long fusions arthrodesis from January 2006 to March 2015 included in this retrospectively study. The patients were divided into two cohorts according the average loss of LL: cohort LL (loss of LL below the average) and cohort GL (loss of LL above the average). Multivariate logistic regression analysis and the receiver operating characteristic curve were used to identify the predictors.

Results

There were statistically significant differences between the two cohorts in preoperative LL (p=0.002), postoperative LL (p=0.036), last follow-up LL (p<0.001), postoperative loss LL (p<0.001), preoperative SVA (p=0.007), last follow-up SVA (p=0.018), and pelvic incidence (p=0.016). Preoperative LL <23.5 (OR=0.920, 95% CI=0.870–0.973, p=0.003) and preoperative sagittal vertical axis >4.28 (OR=1.199, 95% CI=1.007–1.429, p=0.041) had good accuracy to predict postoperative loss of LL.

Conclusions

Loss of LL commonly occurred after long fusions arthrodesis in patients with adult scoliosis. Postoperative deteriorated sagittal balance was more frequently than deteriorated coronal balance. Preoperative LL <23.5 and preoperative SVA >4.28 were the predictors for postoperative greater loss of LL in patients after long fusions arthrodesis. More attention should be paid to how to maintain the LL in patients with preoperative predictors, especially if both the identified predictors are present.

Spinopelvic Parameters in Asymptomatic Subjects Without Spine Disease and Deformity: A Systematic Review With Meta-Analysis

STUDY DESIGN

A systematic review with meta-analysis.

OBJECTIVE

To combine published data, focusing on the development of optimal spinopelvic parameters in adult asymptomatic subjects without spine deformity while taking into consideration the impact of potential confounders.

SUMMARY OF BACKGROUND DATA

A well-grounded approach to define the optimal spinopelvic parameters is necessary for planning surgical correction of spine deformity.

MATERIALS

Selection criteria: (1) randomized and nonrandomized prospective, cross-sectional, and retrospective studies; (2) participants: asymptomatic subjects without spine deformity aged above 18 years; (3) studied parameters: lumbar lordosis (LL), pelvic incidence, sacral slope, and pelvic tilt; (4) potential confounders: method of measurement, sex, age, ethnicity, weight, height, and body mass index. Search method: Ovid MEDLINE (1946-current) and EMBASE (1980-current), all years through October 2015 were included. Data were collected: number of enrolled subjects, means of the studied characteristics, SD, SE of the means, 95% confidence intervals. A meta-analysis was performed to evaluate the pooled means and range of optimal values (pooled mean±pooled SD) taking into consideration the impact of confounders. The GRADE approach was applied to evaluate the level of evidence.

RESULTS

Seventeen of 1018 studies were included (2926 subjects from 9 countries). The pooled means and the optimal ranges were: LL (L1-S1), 54.6 (42-67) degrees; LL (L1-L5), 37.0 (22-53) degrees; pelvic incidence, 50.6 (39-62) degrees; sacral slope, 37.7 (28-48) degrees; pelvic tilt, 12.6 (3-22) degrees. The pooled results were statistically significant (P<0.001), but heterogeneous. Impact of the following confounders was revealed: method of measurement, ethnicity, age, and body mass index. A methodology was created to define an individualized optimal value and range of each studied parameter taking into consideration the influence of confounders.

CONCLUSIONS

The pooled results and developed methodology can be used as diagnostic criteria for evaluation of the spinopelvic parameters, planning of surgical interventions and evaluation of the treatment effect.

Mini-Open Anterior Lumbar Interbody Fusion Combined with Lateral Lumbar Interbody Fusion in Corrective Surgery for Adult Spinal Deformity

STUDY DESIGN

Prospective observational study.

PURPOSE

To introduce the techniques and present the surgical outcomes of mini-open anterior lumbar interbody fusion (ALIF) at the most caudal segments of the spine combined with lateral lumbar interbody fusion (LLIF) for the correction of adult spinal deformity.

OVERVIEW OF LITERATURE

Although LLIF is increasingly used to correct adult spinal deformity, the correction of sagittal plane deformity with LLIF alone is reportedly suboptimal.

METHODS

Thirty-two consecutive patients with adult spinal deformity underwent LLIF combined with mini-open ALIF at the L5-S1 or L4-S1 levels followed by 2-stage posterior fixation. ALIF was performed for a mean 1.3 levels and LLIF for a mean 2.7 levels. Then, percutaneous fixation was performed in 11 patients (percutaneous group), open correction with facetectomy with or without laminectomy in 16 (open group), and additional pedicle subtraction osteotomy (PSO) in 5 (PSO group). Spinopelvic parameters were compared preoperatively and postoperatively. Hospitalization data and clinical outcomes were recorded.

RESULTS

No major medical complications developed, and clinical outcomes improved postoperatively in all groups. The mean postoperative segmental lordosis was greater after ALIF (17.5°±5.5°) than after LLIF (8.1°±5.3°, p <0.001). Four patients (12.5%) had lumbar lordosis with a pelvic incidence of ±9° preoperatively, whereas this outcome was achieved postoperatively in 30 patients (93.8%). The total increase in lumbar lordosis was 14.7° in the percutaneous group, 35.3° in the open group, and 57.0° in the PSO group. The ranges of potential lumbar lordosis increase were estimated as 4°-25°, 23°-42°, and 45°-65°, respectively.

CONCLUSIONS

Mini-open ALIF combined with LLIF followed by posterior fixation may be a feasible technique for achieving optimal sagittal balance and reducing the necessity of more extensive surgery.

Post-surgical functional recovery, lumbar lordosis, and range of motion associated with MR-detectable redundant nerve roots in lumbar spinal stenosis

OBJECTIVE

T1- and T2-weighted magnetic resonance images (MRI) can reveal lumbar redundant nerve roots (RNRs), a result of chronic compression and nerve elongation associated with pathogenesis of cauda equina claudication (CEC) in degenerative lumbar canal stenosis (DLCS). The study investigated effects of lumbar lordosis angle and range of motion on functional recovery in lumbar stenosis patents with and without RNRs.

METHODS

A retrospective study was conducted of 93 lumbar spinal stenosis patients who underwent decompressive surgery. Eligible records were assessed by 3 independent blinded radiologists for presence or absence of RNRs on sagittal T2-weighted MR (RNR and non-RNR groups), pre- and post-operative JOA score, lumbar lordosis angle, and range of motion.

RESULTS

Of 93 total patients, the RNR group (n=37, 21/37 female) and non-RNR group (n=56; 31/56 female) had similar preoperative conditions (JOA score) and were not significantly different in age (mean 64.19 ± 8.25 vs. 62.8 ± 9.41 years), symptom duration (30.92 ± 22.43 vs. 28.64 ± 17.40 months), or follow-up periods (17.35 ± 4.02 vs. 17.75 ± 4.29 mo) (all p>0.4). The non-RNR group exhibited significantly better final JOA score (p=0.015) and recovery rate (p=0.002). RNR group patients exhibited larger lumbar lordosis angles in the neutral position (p=0.009) and extension (p=0.021) and larger range of motion (p=0.008).

CONCLUSIONS

Poorer surgical outcomes in patients with RNRs indicated that elevated lumbar lordosis angle and range of motion increased risks of RNR formation, which in turn may cause poorer post-surgical recovery, this information is possibly useful in prognostic assessment of lumbar stenosis complicated by RNRs.

Estimation of the Ideal Lumbar Lordosis to Be Restored From Spinal Fusion Surgery: A Predictive Formula for Chinese Population

STUDY DESIGN

A prospective, cross-sectional study.

OBJECTIVE

To determine the independent variables associated with lumbar lordosis (LL) and to establish the predictive formula of ideal LL in Chinese population.

SUMMARY OF BACKGROUND DATA

Several formulas have been established in Caucasians to estimate the ideal LL to be restored for lumbar fusion surgery. However, there is still a lack of knowledge concerning the establishment of such predictive formula in Chinese population.

METHODS

A total of 296 asymptomatic Chinese adults were prospectively recruited. The relationships between LL and variables including pelvic incidence (PI), age, sex, and body mass index were investigated to determine the independent factors that could be used to establish the predictive formula. For the validation of the current formula, other 4 reported predictive formulas were included. The absolute value of the gap between the actual LL and the ideal LL yielded by these formulas was calculated and then compared between the 4 reported formulas and the current one to determine its reliability in predicting the ideal LL.

RESULTS

The logistic regression analysis showed that there were significant associations of LL with PI and age (R = 0.508, P < 0.001 for PI; R = 0.088, P = 0.03 for age). The formula was, therefore, established as follows: LL = 0.508 × PI - 0.088 × Age + 28.6. When applying our formula to these subjects, the gap between the predicted ideal LL and the actual LL was averaged 3.9 ± 2.1°, which was significantly lower than that of the other 4 formulas.

CONCLUSION

The calculation formula derived in this study can provide a more accurate prediction of the LL for the Chinese population, which could be used as a tool for decision making to restore the LL in lumbar corrective surgery.

LEVEL OF EVIDENCE

3.