L5/S1 anterior lumbar interbody fusion technique

Early Compensatory Segmental Angle Changes at L3-L4 and L4-L5 After a L5-S1 Interbody Fusion for a Grade 1 Spondylolisthesis

STUDY DESIGN

The retrospective study included patients who underwent an L5-S1 anterior (ALIF) or transforaminal (TLIF) lumbar interbody fusion with posterior pedicle screw instrumentation for grade 1 spondylolisthesis from 2018 to 2022.

OBJECTIVE

To compare early reciprocal changes at the L3-L4 and L4-L5 adjacent levels 6 months after ALIF or TLIF at L5-S1.

BACKGROUND

Degenerative and chronic isthmic spondylolistheses often result in decreased segmental lordosis (SL) at L5-S1. This can lead to lordotic overcompensation at adjacent levels to maintain spinopelvic balance. However, the fate of adjacent angles after interbody fusion is not well understood.

PATIENTS AND METHODS

Preoperative and 6-month postoperative measurements of SL (L3-L4, L4-L5, and L5-S1), lumbar lordosis, and pelvic incidence (PI) were obtained from sagittal standing radiographs. Preliminary t tests were performed for descriptive purposes, and multiple regression was used for hypothesis testing.

RESULTS

Ninety-eight patients met the inclusion criteria (50 ALIF and 48 TLIF). A greater amount of lordosis achieved at L5-S1 was significantly associated with a greater reduction of SL at L4-L5 ( r = -0.65, P < 0.001) or L3-L4 ( r = -0.46, P < 0.001). A greater preoperative PI was associated with a greater reduction of SL at L4-L5 ( r = -0.42, P < 0.001) and at L3-L4 ( r = -0.44, P < 0.001).

CONCLUSION

At 6 months after a lumbar interbody fusion at L5-S1, greater compensatory changes with lordosis reduction are observed at the supra-adjacent L4-L5 and L3-L4 levels in patients achieving greater L5-S1 SL. In addition, preoperative PI played a role in influencing lordotic correction.

Biomechanical Comparison of Different Surgical Approaches for the Treatment of Adjacent Segment Diseases after Primary Transforaminal Lumbar Interbody Fusion: A Finite Element Analysis

BACKGROUND AND OBJECTIVE

Adjacent segment disease (ASD) is a well-known complication after interbody fusion. Revision surgery is necessary for symptomatic ASD to further decompress and fix the affected segment. However, no optimal construct is accepted as a standard in treating ASD. The purpose of this study was to compare the biomechanical effects of different surgical approaches for the treatment of ASD after primary transforaminal lumbar interbody fusion (TLIF).

METHODS

A finite element model of the L1-S1 was conducted based on computed tomography scan images. The primary surgery model was developed with a single-level TLIF at L4-L5 segment. The revision surgical models were developed with anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (LLIF), or TLIF at L3-L4 segment. The range of motion (ROM), intradiscal pressure (IDP), and the stress in cages were compared to investigate the biomechanical influences of different surgical approaches.

RESULTS

The results indicated that all the three surgical approaches can stabilize the spinal segment by reducing the ROM at revision level. The ROM and IDP at adjacent segments of revision model of TLIF was greater than those of other revision models. While revision surgery with ALIF and LLIF had similar effects on the ROM and IDP of adjacent segments. Compared among all the surgical models, cage stress in revision model of TLIF was the maximum in extension and axial rotation.

CONCLUSION

The IDP at adjacent segments and stress in cages of revision model of TLIF was greater than those of ALIF and LLIF. This may be that direct extension of the surgical segment in the same direction results in stress concentration.

Intraoperative Complications of Anterior Lumbar Interbody Fusion: A 5-Year Experience of a Group of Spine Surgeons Performing Their Own Approaches

BACKGROUND

Spine surgery has evolved at an accelerated pace, allowing the development of more efficient surgical techniques while providing a decreasing rate of morbimortality. One example of these approaches is the anterior lumbar interbody fusion (ALIF). The aim of this study was to evaluate the surgical complication rate when performing ALIF without the help of a vascular "access" surgeon.

METHODS

A retrospective descriptive study was conducted at the Hospital Universitario San Ignacio between 2014 and 2018 and included all patients who underwent ALIF during this time. A nonsystematic review was performed assessing approach-related complications in ALIF and the impact of "access" surgeons in surgical outcomes.

RESULTS

A total of 337 patients were included and 508 levels were fused. ALIF was performed as ALIF-360° (27%), ALIF-lateral lumbar interbody fusion (LLIF) (8.9%), and stand-alone ALIF (62%). Most procedures were single-level fusions (51.9%), 45.4% involved 2 levels, and 2.6% were 3-level fusions. The mortality rate was 0%, and only 9 cases of vascular injury were observed and described. Left and common iliac veins were the predominant affected structures. Only a single case required blood transfusion without any other treatment or intensive care unit surveillance.

CONCLUSIONS

Our study is consistent with literature reports about ALIF complications, finding an incidence of 1.7%. Therefore, ALIF is an excellent alternative for spine procedures, especially for the levels L5-S1 that require sagittal balance restoration. The approaches were performed without a vascular "access" surgeon and presented complication rates similar to those described in the literature.

Sonographic Assessment of Human Lumbar Intervertebral Disks: A Cadaveric Study

Objectives:

The intervertebral disk has traditionally been imaged by magnetic resonance imaging (MRI); however, advances in sonography mean it can now be visualized with this modality. The objectives of this human cadaveric study were to visualize the internal structure of the lumbar intervertebral disks and map any defects. Shear wave sonography was explored as a method for assessing the disks.

Materials and Methods:

In a human cadaver, L4-L5 and L5-S1 disks were imaged with sonography through the anterior abdominal wall and directly through the anterior longitudinal ligament. Gray-scale images and shear wave elastography velocities were obtained. An MRI was performed for image comparison.

Results:

Defects in the disks were clearly seen with sonography, imaging through the anterior abdominal wall and also directly through the anterior longitudinal ligament. The defects identified on sonography were less well visualized on MRI. Shear wave velocities could only be obtained from the anterior aspect of the disk and were unreliable, primarily owing to the stiffness of the tissues.

Conclusion:

Sonography can provide an accurate map of defects within the disk, corresponding with MRI. Shear wave elastography should be used with caution in the human cadaveric intervertebral disk, acknowledging the many confounding factors influencing the measurements.

Varicocele complicating an anterior lumbar interbody fusion: a case report

Anterior lumbar interbody fusion (ALIF) is performed for the surgical management of lumbar degenerative disc disease with excellent results, particularly for discogenic low back pain. Commonly reported complications associated with this approach include vessel injury, retrograde ejaculation, and ureteral and viscus organ injury. The development of a varicocele after ALIF has not been previously described in the literature. We report a case of varicocele in a 35-year-old patient who underwent ALIF via a left retroperitoneal approach. No intraoperative complications were identified. The postoperative course was uneventful. He was discharged from the hospital on the 5th postoperative day. Three months after surgery, he complained of discomfort and scrotal pain. Examination revealed a grade 3 varicocele according to the Dubin and Amelar classification. Scrotal Doppler US demonstrated dilatation of the veins of the pampiniform plexus. A lumbar CT scan revealed a bulky left spermatic vein closed to the ureter. The patient was treated with platelet anti-aggregation. He was seen at control intervals of 1, 3 and 5 months. Progress was seen as we had a regression of clinical signs. Varicocele appears as an uncommon complication of ALIF. After reviewing the literature, we describe the occurrence of a varicocele following ALIF, its pathophysiology, and its treatment options.

Predictors of inpatient admission in the setting of anterior lumbar interbody fusion: a Minimally Invasive Spine Study Group (MISSG) investigation

OBJECTIVE

While the anterior lumbar interbody fusion (ALIF) procedure may be amenable to ambulatory surgery, it has been hypothesized that limitations such as the risk of postoperative ileus and vascular complications have hindered transition of this procedure to the outpatient setting. Identification of independent risk factors predisposing patients to inpatient stays of ≥ 24 hours after ALIF may facilitate better postsurgical outcomes, target modifiable risk factors, and assist in the development of screening tools to transition appropriate patients to the ambulatory surgery center (ASC) setting for this procedure. The purpose of this study was to identify the most relevant risk factors that predispose patients to ≥ 24-hour admission following ALIF.

METHODS

A prospectively maintained surgical registry was reviewed for patients undergoing single ALIF between May 2006 and December 2019. Demographics, preoperative diagnosis, perioperative variables, and postoperative complications were evaluated according to their relative risk (RR) elevation for an inpatient stay of ≥ 24 hours. A Poisson regression model was used to evaluate predictors of inpatient stays of ≥ 24 hours. Risk factors for inpatient admission of ≥ 24 hours were identified with a stepwise backward regression model.

RESULTS

A total of 111 patients underwent single-level ALIF (50.9% female and 52.6% male, ≤ 50 years old). Eleven (9.5%) patients were discharged in < 24 hours and 116 remained admitted for ≥ 24 hours. The average inpatient stay was > 2 days (53.7 hours). The most common postoperative complications were fever (body temperature ≥ 100.4°F; n = 4, 3.5%) and blood transfusions (n = 4, 3.5%). Bivariate analysis revealed a preoperative diagnosis of retrolisthesis or lateral listhesis to elevate the RR for an inpatient stay of ≥ 24 hours (RR 1.11, p = 0.001, both diagnoses). Stepwise multivariate analysis demonstrated significant predictors for inpatient stays of ≥ 24 hours to be an operation on L4-5, coexisting degenerative disc disease (DDD) with foraminal stenosis, and herniated nucleus pulposus (RR 1.11, 95% CI 1.03-1.20, p = 0.009, all covariates).

CONCLUSIONS

This study provides data regarding the incidence of demographic and perioperative characteristics and postoperative complications as they pertain to patients undergoing single-level ALIF. This preliminary investigation identified the most relevant risk factors to be considered before appropriately transitioning ALIF procedures to the ASC. Further studies of preoperative characteristics are needed to elucidate ideal ASC ALIF patients.