Is There a Gender-Specific Full Body Sagittal Profile for Different Spinopelvic Relationships? A Study on Propensity-Matched Cohorts

Effect of sagittal spinal alignment on knee pain in patients with severe knee osteoarthritis: A cross-sectional study

BACKGROUND

Sagittal spinal alignment is closely related to knee joint function, and sagittal malalignment can affect knee joint pain. This study investigated the association between knee joint pain intensity and sagittal spinal alignment in patients with knee osteoarthritis.

METHODS

This retrospective study enrolled 187 patients with knee osteoarthritis who were scheduled for primary unilateral total knee arthroplasty (TKA) from December 2021 to March 2023. Patients were assigned to either the Normal or Imbalance group according to the pelvic incidence (PI) minus lumbar lordosis (LL) values. Knee joint function was compared between patients with and without matched sagittal spinal alignment. The primary outcome was patient-reported pain intensity.

RESULTS

A total of 132 patients (22 men and 110 women, mean age: 75 ± 6.7 years [range, 55-89 years], mean body mass index: 25.3 ± 3.8 kg/m²) were evaluated preoperatively. The Imbalance group categorized by PI minus LL values (≥10) comprised 45 patients (34 %, mean age: 76.5 ± 5.9 years, mean body mass index: 25.5 ± 3.3 kg/m²). The mean pain intensity on the affected side was significantly higher in the Imbalance group (P = 0.020). No differences in psychosocial factors were found between the two groups. Knee joint function regarding knee joint extension angle in the standing position was significantly greater in the Imbalance group (P = 0.035).

CONCLUSION

Sagittal plane malalignment was associated with knee joint pain in patients with knee osteoarthritis who were scheduled for TKA. Our results suggest the need for preoperative pain control interventions that consider the effects of sagittal spinal alignment.

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

PURPOSE

To develop age- and BMI-adjusted alignment targets to improve patient-specific management and operative treatment outcomes.

METHODS

Retrospective review of a single-center stereographic database. ASD patients receiving operative or non-operative treatment, ≥ 18y/o with complete baseline (BL) ODI scores and radiographic parameters (PT, SVA, PILL, TPA) were included. Patients were stratified by age consistent with US-Normative values (norms) of SF-36(< 35, 35-55, 45-54, 55-64, 65-74, ≥ 75y/o), and dichotomized by BMI (Non-Obese < 30; Obese ≥ 30). Linear regression analysis established normative age- and BMI-specific radiographic thresholds, utilizing previously published age-specific US-Normative ODI values converted from SF-36 PCS (Lafage et al.), in conjunction with BL age and BMI means.

RESULTS

486 patients were included (Age: 52.5, Gender: 68.7%F, mean BMI: 26.2, mean ODI: 32.7), 135 of which were obese. Linear regression analysis developed age- and BMI-specific alignment thresholds, indicating PT, SVA, PILL, and TPA to increase with both increased age and increased BMI (all R > 0.5, p < 0.001). For non-obese patients, PT, SVA, PILL, and TPA ranged from 10.0, - 25.8, - 9.0, 3.1 in patients < 35y/o to 27.8, 53.4, 17.7, 25.8 in patients ≥ 75 y/o. Obese patients' PT, SVA, PILL, and TPA ranged from 10.5, - 7.6, - 7.1, 5.8 in patients < 35 y/o to 28.3, 67.0, 19.15, 27.7 in patients ≥ 75y/o. Normative SVA values in obese patients were consistently ≥ 10 mm greater compared to non-obese values, at all ages.

CONCLUSION

Significant associations exist between age, BMI, and sagittal alignment. While BMI influenced age-adjusted alignment norms for PT, SVA, PILL, and TPA at all ages, obesity most greatly influenced SVA, with normative values similar to non-obese patients who were 10 years older. Age-adjusted alignment thresholds should take BMI into account, calling for less rigorous alignment objectives in older and obese patients.

Characteristics of the sagittal spinal balance in the asymptomatic elderly Chinese population

PURPOSE

To investigate the normal values of the sagittal spinal parameters and analyze the distribution of the global spinal profiles in a Chinese population with age over 75.

METHODS

Two hundred and twelve sets of the whole spine lateral radiographs were obtained from a database of an asymptomatic elderly population. Global and regional spinal parameters were measured. Sagittal profiles were determined according to the Roussouly classification compared with previous studies involving different populations.

RESULTS

A total of 102 elderly subjects (≥ 75 years) were enrolled with an average age of 79.24 ± 3.53 years. The mean values of the spinopelvic parameters were 42.89 ± 11.64° for TK, 13.84 ± 10.78° for TLK, 44.48 ± 12.88° for LL, 44.76 ± 9.84° for PI, 17.19 ± 8.08° for PT, 28.35 ± 7.94° for SS, 3.47 ± 3.56 cm for SVA, 14.75 ± 7.85° for TPA, -0.27 ± 11.95° for PI-LL, respectively. Subjects ≥ 75 years were found to have significantly smaller LL and SS, but greater TLK, PT, SVA, TPA, and PI-LL than those 60-74 years (p < 0.05). Significant age- and sex-dependent differences were found in the Roussouly classification's distribution between the two subgroups.

CONCLUSIONS

The normal values of the sagittal parameters were presented in the elderly Chinese asymptomatic population (≥ 75 years). Ethnic, age, and sex displayed significant effects on the behaviors of the sagittal spinal balance and profiles. These results could be served as physiological references for the planning of surgical strategies in elderly Chinese patients over 75 years.

Characteristics of sagittal spinopelvic alignment in asymptomatic Han Chinese adults

The aim of the present study was to investigate patterns of spine sagittal alignment in asymptotic patients using radiological analysis. A number of studies focused on investigating normal patterns of spinal and pelvic alignment in Chinese populations, while few have evaluated Caucasian and other Asian populations. A total of 10 relevant pelvic and spinal parameters, including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), cervical lordosis (CL), thoracic kyphosis (TK), sagittal vertical axis (SVA), lumbopelvic lordosis angle (PR-T12), spino-sacral angle (SSA) and sacral pelvic angle (SPA), were evaluated in asymptomatic Chinese adults from Beijing, aged 21–65 years. Correlations among these parameters, as well as between these parameters and age, and associations with gender and body mass index (BMI) were assessed using Pearson's correlation analysis. A total of 39 males and 46 females, aged 50.9±13.2 and 41.8±13.6 years, respectively, were enrolled in the present study. The results of PI, PT, SS, LL, TK, CL, SVA, PR-T12, SSA and SPA values suggested that age was positively correlated with TK, CL and SVA, while it was negatively correlated with LL, PR-T12 and SSA. SSA and SVA were revealed to differ significantly between sexes. It was also demonstrated that LL and TK may be associated with BMI. In conclusion, the results of the present study indicate that spinopelvic parameters in the asymptomatic Chinese Han population (in Beijing) are correlated with age and may be associated with individuals' ethnicity, sex and BMI. The results of the current study may provide a basis for the restoration of LL or similar diseases.

The impact of obesity on compensatory mechanisms in response to progressive sagittal malalignment

BACKGROUND CONTEXT

Obesity's impact on standing sagittal alignment remains poorly understood, especially with respect to the role of the lower limbs. Given energetic expenditure in standing, a complete understanding of compensation in obese patients with sagittal malalignment remains relevant.

PURPOSE

This study compares obese and non-obese patients with progressive sagittal malalignment for differences in recruitment of pelvic and lower-limb mechanisms.

STUDY DESIGN/SETTING

Single-center retrospective review.

PATIENT SAMPLE

A total of 554 patients (277 obese, 277 non-obese) were identified for analysis.

OUTCOME MEASURES

Upper body alignment parameters: sagittal vertical axis (SVA) and T1 spinopelvic inclination (T1SPi). Compensatory lower-limb mechanisms: pelvic translation (pelvic shift [PS]), knee (KA) and ankle (AA) flexion, hip extension (sacrofemoral angle [SFA]), and global sagittal angle (GSA).

METHODS

Inclusion criteria were patients ≥18 years who underwent full-body stereographic x-rays. Included patients were categorized as non-obese (N-Ob: body mass index [BMI]<30 kg/m²) or obese (Ob: BMI≥30 kg/m²). To control for potential confounders, groups were propensity score matched by age, gender, and baseline pelvic incidence (PI), and subsequently categorized by increasing spinopelvic (pelvic incidence minus lumbar lordosis [PI-LL]) mismatch: <10°, 10°-20°, >20°. Independent t tests and linear regression models compared sagittal (SVA, T1SPi) and lower limb (PS, KA, AA, SFA, GSA) parameters between obesity cohorts.

RESULTS

A total of 554 patients (277 Ob, 277 N-Ob) were included for analysis and were stratified to the following mismatch categories: <10°: n=367; 10°-20°: n=91; >20°: n=96. Obese patients had higher SVA, KA, PS, and GSA than N-Ob patients (p<.001 all). Low PI-LL mismatch Ob patients had greater SVA with lower SFA (142.22° vs. 156.66°, p=.032), higher KA (5.22° vs. 2.93°, p=.004), and higher PS (4.91 vs. -5.20 mm, p<.001) than N-Ob patients. With moderate PI-LL mismatch, Ob patients similarly demonstrated greater SVA, KA, and PS, combined with significantly lower PT (23.69° vs. 27.14°, p=.012). Obese patients of highest (>20°) PI-LL mismatch showed greatest forward malalignment (SVA, T1SPi) with significantly greater PS, and a concomitantly high GSA (12.86° vs. 9.67°, p=.005). Regression analysis for lower-limb compensation revealed that increasing BMI and PI-LL predicted KA (r²=0.234) and GSA (r²=0.563).

CONCLUSIONS

With progressive sagittal malalignment, obese patients differentially recruit lower extremity compensatory mechanisms, whereas non-obese patients preferentially recruit pelvic mechanisms. The ability to compensate for progressive sagittal malalignment with the pelvic retroversion is limited by obesity.

Full-Body Analysis of Age-Adjusted Alignment in Adult Spinal Deformity Patients and Lower-Limb Compensation

STUDY DESIGN

Single-center retrospective review.

OBJECTIVE

The present study evaluates the effect of increasing spinal deformity deviation from age-adjusted alignment ideals on lower extremity compensation.

SUMMARY OF BACKGROUND DATA

Although current understanding of compensatory mechanisms in adult spinal deformity (ASD) is progressing due to full-body stereographic assessment, the effect of age-adjusted deformity targets on lower-limb compensation remains unexamined.

METHODS

ASD patients 18 years or older with biplanar full-body stereographic x-rays were included. Patients were stratified into age cohorts: younger than 40 years, 40-65 years, 65 years or older. Age-specific alignment goals (IDEAL) for pelvic tilt (PT), spinopelvic mismatch (PI-LL), sagittal vertical axis (SVA), and T1 pelvic angle (TPA) were calculated for each patient using published formulas and compared to patients' real (ACTUAL) radiographic parameters. The difference between ACTUAL and IDEAL alignment (OFFSET) was calculated. Analysis of variance compared ACTUAL, IDEAL, and OFFSET between age groups, and OFFSET was correlated with lower-limb compensation (sacrofemoral angle, pelvic shift, knee angle, ankle angle).

RESULTS

Seven hundred seventy-eight patients with (74.1% female) were included. ACTUAL and IDEAL alignments matched for PT (P = 0.37) in patients younger than 40 years, SVA (P = 0.12) in patients 40 to 65 years and PT, SVA, and TPA (P > 0.05) in patients 65 years or older. SVA and TPA OFFSETs decreased significantly with increasing age (P < 0.001). Hip extension correlated with all OFFSETs in patients younger than 40 years (positively with PT, PI-LL, TPA; negatively with SVA). Knee flexion correlated with PI-LL, SVA, and TPA, across all age groups with strongest correlations (0.525 < r < 0.605) in patients 40 to 65 years. Ankle dorsiflexion only correlated positively with PT and PI-LL offsets in older (older than 40 years) age groups. Posterior pelvic displacement correlated positively with all OFFSET groups, and was highest (0.526 < r <0.712) in patients ages 40 to 65 years.

CONCLUSION

Age-adjusted ideals for sagittal alignment provide targets for patients with ASD. Offsets from actual alignment (more severe sagittal deformity) revealed differential recruitment of lower-limb extension, which varied significantly with age.

LEVEL OF EVIDENCE

3.