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

Lumbar Apex Position as an Independent Risk Factor for Adjacent Segment Diseases in Patients Undergoing Short-Level Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate whether lumbar apex position had an impact on the development of adjacent segment disease (ASD) following transforaminal lumbar interbody fusion (TLIF).

SUMMARY OF BACKGROUND DATA

Previous studies have demonstrated that solely concentrating on lumbar lordosis value is not suitable, and neglecting the significance of lumbar apex can lead to mechanical complications. However, the relationship between lumbar apex and ASD is still not well understood.

METHODS

In this retrospective study, 234 consecutive patients who underwent L3-5 or L4-5 TLIF for degenerative diseases were reviewed. The study evaluated the associations between sagittal parameters and pelvic incidence (PI). Patients were labeled "matched" when lumbar apex position aligned with the theoretical target, and "mismatched" when it did not. Multivariate analysis was applied to find the independent risk factors of ASD. In addition, a focused subanalysis was performed based on the lumbar apex position (ideal match, cranial from ideal, and caudal from ideal).

RESULTS

After an average follow-up period of 70.6 months, 68 cases were identified as having ASD. Postoperatively, 64.7% (44 of 68) of the patients with ASD exhibited a mismatched lumbar apex, compared with 41% (68 of 166) of those without ASD ( P < 0.001). PI correlated significantly with proximal lordosis (PL) and lordosis distribution index (LDI) but not with distal lordosis (DL). Multivariate analysis identified age, L3-5 fusion, postoperative DL, and postoperative mismatched lumbar apex as independent risk factors of ASD. Upon the subanalysis, it was discovered that there were unique compensatory strategies in the cranial and caudal groups, with notable variations in postoperative DL, PL, and LDI among three groups (all P value of <0.05).

CONCLUSION

Lumbar apex position significantly influenced the risk of ASD. To restore the lumbar apex to its ideal position, a proper value and distribution of DL should be attained.

LEVEL OF EVIDENCE

4.

A systematic review and update on diagnosis and treatment of new onset sacroiliac joint dysfunction after lumbar fusion

BACKGROUND

Sacroiliac joint dysfunction (SIJD) after lumbar/lumbosacral fusion has become increasingly recognized as the utilization of lumbar fusion has grown. Despite the significant morbidity associated with this condition, uncertainty regarding its diagnosis and treatment remains. We aim to update the current knowledge of the etiology, diagnosis, and treatment of post-lumbar surgery SIJD.

METHODS

PRISMA guidelines were used to search the PubMed/Medline, Web of Science, Cochrane Reviews, Embase, and OVID databases for literature published in the last 10 years. The ROBIS tool was utilized for risk of bias assessment. Statistical analyses were performed using the R foundation. A Fisher's exact test was performed to determine the risk of SIJD based on operative technique, gender, and symptom onset timeline. Odds ratios were reported with 95% confidence intervals. A p-value [Formula: see text] 0.05 was considered statistically significant.

RESULTS

Seventeen publications were included. The incidence of new onset SIJD was 7.0%. The mean age was 56 years, and the follow-up length was 30 months. SIJD was more common with fixed lumbar fusion vs floating fusion (OR = 1.48 [0.92, 2.37], p = 0.083), fusion of [Formula: see text] 3 segments (p < 0.05), and male gender increased incidence of SIJD (OR = 1.93 [1.27, 2.98], p = 0.001). Intra-articular injection decreased the Visual Analogue Scale (VAS) score by 75%, while radiofrequency ablation (RFA) reduced the score by 90%. An open approach resulted in a 13% reduction in VAS score versus 68 and 29% for SIJ fixation using the iFuse and DIANA approaches, respectively.

CONCLUSIONS

Lumbar fusion predisposes patients to SIJD, likely through manipulation of the SIJ's biomechanics. Definitive diagnosis of SIJD remains multifaceted and a newer modality such as SPECT/CT may find a future role. When conservative measures are ineffective, RFA and SIJ fixation using the iFuse System yield the greatest improvement VAS and ODI.

The Thoracolumbar Inflection Point in a Population of Asymptomatic Volunteers: A Multi-Ethnic Alignment Normative Study Cohort Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To show population variance in the Inflection Point (IP) and its role in defining maximum Thoracic Kyphosis (TK) and Lumbar Lordosis (LL).

METHODS

468 asymptomatic adult volunteers were included in the Multi-Ethnic Normative Alignment Study (MEANS). To find parameters correlating with IP, the vertebrae and discs were numbered such that C7 was 0, T1 was 1, with T1-T2 disc being 1.5, etc. Statistical analysis was performed by a correlation matrix for IP and the 9 other selected parameters along with linear regressions.

RESULTS

The overall mean IP was 12.44 approximately corresponding to T12-L1 disc with the median being 12.50, range was T8-L4. The cohort was then stratified by sex and ethnicity, but there was no significant difference in IP between groups. IP in younger subjects was 13 (L1), compared to 12.5 (T12-L1 disc) in older subjects (P < .05). IP was moderately correlated with the TK apex (r = .66). No strong correlation was found between IP and LL magnitude or apex, TK magnitude, sacral slope, or Pelvic Incidence (PI). In terms of other sagittal parameters, PI and LL demonstrated a significant positive correlation. PI and TK did not have a strong association.

CONCLUSIONS

The mean IP was at the T12-L1 disc, however IP ranged from T8 to L4. Older subjects tended to have a relatively more cephalad IP. No radiographic variable was found to be a strong predictor of the IP. TK apex was found to have a moderate correlation.