Defining age-adjusted spinopelvic alignment thresholds: should we integrate BMI?

The relationship between spinopelvic alignment and knee osteoarthritis in female patients: A cross-sectional study

BackgroundThe spine, pelvis, and lower extremities move in the form of a kinematic chain.ObjectiveThis study aimed to evaluate the relationship between spinopelvic parameters and knee osteoarthritis.MethodsSixty-nine participants (50-70 years) were diagnosed with knee osteoarthritis: early-stage (n = 36) and late-stage (n = 33). Knee osteoarthritis severity was assessed using standing antero-posterior radiographs (Kellgren-Lawrence scores). A visual Analog Scale was used to evaluate knee and lumbar pain, the Western Ontario and McMaster Universities Osteoarthritis Index to evaluate knee joint function and disability, and the Oswestry Low Back Pain Disability Index to evaluate disability associated with lumbar pain. Lateral scoliosis radiographs were taken of all the study participants; pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis values were measured and recorded.ResultsMultivariate logistic regression analysis was performed to determine the independent risk factors associated with the clinical and radiological osteoarthritis severity as Body Mass Index, sagittal vertical axis and lumbopelvic mismatch increased. The sacral slope values were determined to be independently negatively correlated with the clinical osteoarthritis severity. However, no correlation was determined with the radiological severity.ConclusionIn this study, we determined that global sagittal imbalance and lumbopelvic mismatch are associated with advanced knee osteoarthritis. Although pelvic retroversion was not found to be correlated with the radiographic severity of osteoarthritis, it was found to be associated with poor functional results.

Are Surgical Outcomes Different According to Baseline Balance Status in Elderly Patients with Degenerative Sagittal Imbalance?

STUDY DESIGN

This is a retrospective study.

OBJECTIVE

We sought to compare surgical outcomes according to baseline balance statuses in elderly patients with degenerative sagittal imbalance (DSI).

SUMMARY OF BACKGROUND

Although optimal sagittal correction has been emphasized for good surgical outcomes, the effect of the state of preoperative balance on surgical outcomes has been adequately described at present.

METHODS

Patients aged 60 years and above with DSI who underwent ≥5-level fusion to the sacrum were included. Among them, only those who postoperatively achieved the optimal age-adjusted pelvic incidence (PI) - lumbar lordosis (LL) target were included in this study. Study participants were divided into two groups according to their preoperative sagittal vertical axis (SVA): compensatory balance (SVA <5 cm, group CB) and decompensation (SVA ≥5 cm, group D). Comparisons between the two groups were performed using the χ 2 test or Fisher exact test for categorical variables and the independent t -test or Wilcoxon rank-sum test for continuous variables.

RESULTS

A total of 156 patients whose postoperative sagittal alignment matched the age-adjusted PI-LL target constituted the study cohort. There were 59 patients in group CB and 97 patients in group D. Mean follow-up duration was 50.0 months after surgery. Immediate postoperatively, sacral slope and SVA were significantly greater in group D than in group CB. At the last follow-up, the SVA was significantly greater in group D than in group CB (43.6 vs. 22.7 mm), while no significant differences were found in other sagittal parameters. The Oswestry disability index and Scoliosis Research Society -22 scores at the last follow-up were significantly worse in group D than in group CB.

CONCLUSION

The SVA tended to experience less correction postoperatively, with evidence of further deterioration during follow-up in group D than in group CB. This suboptimal correction of SVA may contribute to the inferior clinical outcomes encountered in group D relative to group CB. Therefore, we recommend correction of PI-LL as close as possible to the lower limit of the suggested PI-LL target range in patients with evidence of preoperative decompensation.

Hook Fixation at Uppermost Instrumented Vertebra +1 Reduced Proximal Junctional Failure in Adult Patients With Spinal Deformity Having Achieved Optimal Deformity Correction by Sagittal Age-Adjusted Score

BACKGROUND AND OBJECTIVES

Appropriate correction relative to the age-adjusted sagittal alignment target reduces the proximal junctional failure (PJF) risk. Nonetheless, a considerable number of patients suffer from PJF despite optimal correction. The aim of this study was to identify the risk factors of PJF that occurs despite optimal correction relative to the sagittal age-adjusted score (SAAS) in adult spinal deformity surgery.

METHODS

Patients aged 60 years or older with adult spinal deformity who underwent ≥5-level fusion to the sacrum were initially screened. Among them, only patients who achieved optimal sagittal correction relative to the SAAS were included in the study. Optimal correction was defined as the SAAS point between -1 and +1. Various clinical and radiographic factors were compared between the PJF and no PJF groups and were further evaluated using multivariate analysis.

RESULTS

The final study cohort comprised 127 patients. The mean age was 67 years, and there were 111 women (87.4%). A mean of total fusion length was 7.2. PJF occurred in 42 patients (33.1%), while 85 patients (66.9%) did not develop PJF. Multivariate analysis showed that a high body mass index (odds ratio [OR] = 1.153, 95% CI = 1.027-1.295, P = .016), a higher lordosis distribution index (LDI) (OR = 1.024, 95% CI = 1.003-1.045, P = .022), and no use of hook fixation (OR = 9.708, 95% CI = 1.121-76.923, P = .032) were significant risk factors of PJF development. In the receiver operating characteristic curve analysis, the cutoff value for the LDI was calculated as 61.0% (area under the curve = 0.790, P < .001).

CONCLUSION

PJF developed in a considerable portion of patients despite optimal correction relative to the age-adjusted alignment. The risk factors of PJF in this patient group were high body mass index, high LDI exceeding 61%, and no use of hook fixation. PJF could be further decreased by properly managing these risk factors along with optimal sagittal correction.

Full-body Postural Alignment Analysis Through Barycentremetry

STUDY DESIGN

A multicentric retrospective study.

OBJECTIVE

The study of center of mass (COM) locations (ie, barycentremetry) can help us understand postural alignment. The goal of this study was to determine relationships between COM locations and global postural alignment x-ray parameters in healthy subjects. The second objective was to determine the impact on the spinopelvic alignment of increased distance between the anterior body envelope and spine at the lumbar apex level.

SUMMARY OF BACKGROUND DATA

Unexplored relationship between COM location and spinopelvic parameters.

METHODS

This study included healthy volunteers with full-body biplanar radiographs, including body envelope reconstruction, allowing the estimation of COM location. The following parameters were analyzed: lumbar lordosis (LL), thoracic kyphosis (TK), cervical lordosis (CL), pelvic tilt (PT), sacro-femoral angle (SFA), knee flexion angle (KFA), and sagittal odontoid-hip axis angle (ODHA). The following COM in the sagittal plane were located: whole body, at a thoracolumbar inflection point, and body segment above TK apex. The body envelope reconstruction also provided the distance between the anterior skin and the LL apex vertebral body center ("SV-L distance").

RESULTS

This study included 124 volunteers, with a mean age of 44±19.3. Multivariate analysis confirmed the posterior translation of COM above TK apex with increasing LL ( P =0.002) through its proximal component and posterior shift of COM at the inflection point with increasing TK ( P =0.008). Increased SV-L distance was associated with greater ODHA ( r =0.4) and more anterior body COM ( r =0.5), caused by increased TK ( r =0.2) and decreased proximal and distal LL (both r =0.3), resulting in an augmentation in SFA ( r =0.3) (all P <0.01).

CONCLUSIONS

Barycentremetry showed that greater LL was associated with a posterior shift of COM above the thoracic apex, while greater TK was correlated with more posterior COM at inflection point. Whole-body COM was strongly correlated with ODHA. This study also exhibited significant alignment disruption associated with increased abdominal volume, with compensatory hip extension.

LEVEL OF EVIDENCE

Level-II.

The Impact of Lumbopelvic Realignment Versus Prevention Strategies at the Upper-instrumented Vertebra on the Rates of Junctional Failure Following Adult Spinal Deformity Surgery

STUDY DESIGN/SETTING

Retrospective.

OBJECTIVE

Evaluate the surgical technique that has the greatest influence on the rate of junctional failure following ASD surgery.

SUMMARY OF BACKGROUND DATA

Differing presentations of adult spinal deformity(ASD) may influence the extent of surgical intervention and the use of prophylaxis at the base or the summit of a fusion construct to influence junctional failure rates.

MATERIALS AND METHODS

ASD patients with two-year(2Y) data and at least 5-level fusion to the pelvis were included. Patients were divided based on UIV: [Longer Construct: T1-T4; Shorter Construct: T8-T12]. Parameters assessed included matching in age-adjusted PI-LL or PT, aligning in GAP-relative pelvic version or Lordosis Distribution Index. After assessing all lumbopelvic radiographic parameters, the combination of realigning the two parameters with the greatest minimizing effect of PJF constituted a good base. Good s was defined as having: (1) prophylaxis at UIV (tethers, hooks, cement), (2) no lordotic change(under-contouring) greater than 10° of the UIV, (3) preoperative UIV inclination angle<30°. Multivariable regression analysis assessed the effects of junction characteristics and radiographic correction individually and collectively on the development of PJK and PJF in differing construct lengths, adjusting for confounders.

RESULTS

In all, 261 patients were included. The cohort had lower odds of PJK(OR: 0.5,[0.2-0.9]; P =0.044) and PJF was less likely (OR: 0.1,[0.0-0.7]; P =0.014) in the presence of a good summit. Normalizing pelvic compensation had the greatest radiographic effect on preventing PJF overall (OR: 0.6,[0.3-1.0]; P =0.044). In shorter constructs, realignment had a greater effect on decreasing the odds of PJF(OR: 0.2,[0.02-0.9]; P =0.036). With longer constructs, a good summit lowered the likelihood of PJK(OR: 0.3,[0.1-0.9]; P =0.027). A good base led to zero occurrences of PJF. In patients with severe frailty/osteoporosis, a good summit lowered the incidence of PJK(OR: 0.4,[0.2-0.9]; P =0.041) and PJF (OR: 0.1,[0.01-0.99]; P =0.049).

CONCLUSION

To mitigate junctional failure, our study demonstrated the utility of individualizing surgical approaches to emphasize an optimal basal construct. Achievement of tailored goals at the cranial end of the surgical construct may be equally important, especially for higher-risk patients with longer fusions.

LEVEL OF EVIDENCE

3.