Postoperative Sagittal Balance Has Only a Limited Role in the Development of Adjacent Segment Disease After Lumbar Spine Fusion for Degenerative Lumbar Spine Disorders: A Subanalysis of the 10-year Follow-up Study

Sagittal Alignment in the Degenerative Lumbar Spine: Surgical Planning

➤ Sagittal alignment of the spine has gained attention in the field of spinal deformity surgery for decades. However, emerging data support the importance of restoring segmental lumbar lordosis and lumbar spinal shape according to the pelvic morphology when surgically addressing degenerative lumbar pathologies such as degenerative disc disease and spondylolisthesis.➤ The distribution of caudal lordosis (L4-S1) and cranial lordosis (L1-L4) as a percentage of global lordosis varies by pelvic incidence (PI), with cephalad lordosis increasing its contribution to total lordosis as PI increases.➤ Spinal fusion may lead to iatrogenic deformity if performed without attention to lordosis magnitude and location in the lumbar spine.➤ A solid foundation of knowledge with regard to optimal spinal sagittal alignment is beneficial when performing lumbar spinal surgery, and thoughtful planning and execution of lumbar fusions with a focus on alignment may improve patient outcomes.

Determining a relative total lumbar range of motion to alleviate adjacent segment degeneration after transforaminal lumbar interbody fusion: a finite element analysis

BACKGROUND

A reduction in total lumbar range of motion (ROM) after lumbar fusion may offset the increase in intradiscal pressure (IDP) and facet joint force (FJF) caused by the abnormally increased ROM at adjacent segments. This study aimed to determine a relative total lumbar ROM rather than an ideal adjacent segment ROM to guide postoperative waist activities and further delay adjacent segment degeneration (ASD).

METHODS

An intact L1-S1 finite element model was constructed and validated. Based on this, a surgical model was created to allow the simulation of L4/5 transforaminal lumbar interbody fusion (TLIF). Under the maximum total L1-S1 ROM, the ROM, IDP, and FJF of each adjacent segment between the intact and TLIF models were compared to explore the biomechanical influence of lumbar fusion on adjacent segments. Subsequently, the functional relationship between total L1-S1 ROM and IDP or total L1-S1 ROM and FJF was fitted in the TLIF model to calculate the relative total L1-S1 ROMs without an increase in IDP and FJF.

RESULTS

Compared with those of the intact model, the ROM, IDP, and FJF of the adjacent segments in the TLIF model increased by 12.6-28.9%, 0.1-6.8%, and 0-134.2%, respectively. As the total L1-S1 ROM increased, the IDP and FJF of each adjacent segment increased by varying degrees. The relative total L1-S1 ROMs in the TLIF model were 11.03°, 12.50°, 12.14°, and 9.82° in flexion, extension, lateral bending, and axial rotation, respectively.

CONCLUSIONS

The relative total L1-S1 ROMs after TLIF were determined, which decreased by 19.6-29.3% compared to the preoperative ones. Guiding the patients to perform postoperative waist activities within these specific ROMs, an increase in the IDP and FJF of adjacent segments may be effectively offset, thereby alleviating ASD.

Validation of Roussouly classification in predicting the occurrence of adjacent segment disease after short-level lumbar fusion surgery

BACKGROUND

Recent studies demonstrated that restoring sagittal alignment to the original Roussouly type can remarkably reduce complication rates after adult spinal deformity surgery. However, there is still no data proving the benefit of maintaining ideal Roussouly shape in the lumbar degenerative diseases and its association with the development of adjacent segment disease (ASD). Thus, this study was performed to validate the usefulness of Roussouly classification to predict the occurrence of ASD after lumbar fusion surgery.

MATERIALS AND METHODS

This study retrospectively reviewed 234 consecutive patients with lumbar degenerative diseases who underwent 1- or 2-level fusion surgery. Demographic and radiographic data were compared between ASD and non-ASD groups. The patients were classified by both "theoretical" [based on pelvic incidence (PI)] and "current" (based on sacral slope) Roussouly types. The patients were defined as "matched" if their "current" shapes matched the "theoretical" types and otherwise as "mismatched". The logistic regression analysis was performed to identify the factors associated with ASD. Finally, clinical data and spinopelvic parameters of "theoretical" and "current" types were compared.

RESULTS

With a mean follow-up duration of 70.6 months, evidence of ASD was found in the 68 cases. Postoperatively, ASD group had more "current" shapes classified as type 1 or 2 and fewer as type 3 than the non-ASD group (p < 0.001), but the distribution of "theoretical" types was similar between groups. Moreover, 80.9% (55/68) of patients with ASD were mismatched, while 48.2% (80/166) of patients without ASD were mismatched (p < 0.001). A multivariate analysis identified age [odds ratio (OR) = 1.058)], 2-level fusion (OR = 2.9830), postoperative distal lordosis (DL, OR = 0.949) and mismatched Roussouly type (OR = 4.629) as independent risk factors of ASD. Among the four "theoretical" types, type 2 had the lowest lumbar lordosis, DL, and segmental lordosis. When considering the "current" types, current type 2 was associated with higher rates of 2-level fusion, worse DL, and greater pelvic tilt compared with other current types.

CONCLUSIONS

DL loss and mismatched Roussouly type were significant risk factors of ASD. To decrease the incidence of ASD, an appropriate value of DL should be achieved to restore sagittal alignment back to the ideal Roussouly type.

LEVEL OF EVIDENCE

Level 4.

Influence of rapid recovery nutritional support on functional recovery and hospitalization duration in patients undergoing minimally invasive lumbar surgery

OBJECTIVE

To examine the impact of a nutrition support model, specifically focused on rapid recovery, on postoperative recovery in patients with degenerative lumbar spinal stenosis who underwent minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

METHODS

A retrospective analysis was conducted, utilizing the medical records of 114 patients with degenerative lumbar spinal stenosis who underwent MIS-TLIF at the Affiliated Hospital of Gansu University of Chinese Medicine from February 2020 to October 2022. Among these patients, 63 individuals received a nutrition support model based on the concept of rapid recovery, comprising the observation group, while the remaining 51 patients received conventional postoperative support, forming the control group. The study compared the post-intervention lumbar function recovery, postoperative pain score, perioperative hospital stay, and patient satisfaction with nursing work between the two groups.

RESULTS

There was no statistically significant difference in the Japanese Orthopaedic Association (JOA) score and Oswestry Disability Index (ODI) at 6 months after the intervention between the two groups (P>0.05). Similarly, there was no statistically significant difference in the modified Barthel index and visual analog scale scores at 6 months after the intervention between the two groups (P>0.05). In terms of operation time and intraoperative blood loss, there was no statistically significant difference observed between the observation group and the control group (P>0.05). However, when compared to the control group, the observation group showed significant shorter hospital stay and time to ambulation after the intervention, leading to a decrease in treatment cost (P<0.01). Multivariate logistic regression analysis revealed that age, history of diabetes, nursing plan, operation time, and preoperative JOA score were identified as independent risk factors for prolonged hospital stay (P<0.05).

CONCLUSION

The nutrition support model, which is based on the concept of rapid recovery, has been found to have several benefits for patients with degenerative lumbar spinal stenosis undergoing MIS-TLIF. These benefits include reducing the hospital stay, treatment cost, and the time to ambulation. Additionally, logistic regression analysis has identified several independent risk factors that can affect the length of hospital stay. These risk factors include age, history of diabetes, nursing plan, operation time, and preoperative JOA score.