Anterior lumbar interbody fusion: two-year results with a modular interbody device

Review of mechanisms of expandable spine surgery devices

INTRODUCTION

Expandable devices such as interbody cages, vertebral body reconstruction cages, and intravertebral body expansion devices are frequently utilized in spine surgery. Since the introduction of expandable implants in the early 2000s, the variety of mechanisms that drive expansion and implant materials have steadily increased. By examining expandable devices that have achieved commercial success and exploring emerging innovations, we aim to offer an in-depth evaluation of the different types of expandable cages used in spine surgery and the underlying mechanisms that drive their functionality.

AREAS COVERED

We performed a review of expandable spinal implants and devices by querying the National Library of Medicine MEDLINE database and Google Patents database from 1933 to 2024. Five major types of mechanical jacks that drive expansion were identified: scissor, pneumatic, screw, ratchet, and insertion-expansion.

EXPERT OPINION

We identified a trend of screw jack mechanism being the predominant machinery in vertebral body reconstruction cages and scissor jack mechanism predominating in interbody cages. Pneumatic jacks were most commonly found in kyphoplasty devices. Critically reviewing the mechanisms of expansion and identifying trends among effective and successful cages allows both surgeons and medical device companies to properly identify future areas of development.

Expandable Cage Technology-Transforaminal, Anterior, and Lateral Lumbar Interbody Fusion

This review of the literature will focus on the indications, surgical techniques, and outcomes for expandable transforaminal lumbar interbody fusion (TLIF), anterior lumbar interbody fusion (ALIF), and lateral lumbar interbody fusion (LLIF) operations. The expandable TLIF cage has become a workhorse for common degenerative pathology, whereas expandable ALIF cages carry the promise of greater lordotic correction while evading the diseased posterior elements. Expandable LLIF cages call upon minimally invasive techniques for a retroperitoneal, transpsoas approach to the disc space, obviating the need for an access surgeon and decreasing risk of injury to the critical neurovascular structures. Nuances between expandable and static cages for all 3 TLIF, ALIF, and LLIF operations are discussed in this review.

ALIF in the correction of spinal sagittal misalignment. A systematic review of literature

PURPOSE

We aim at analysing the impact of anterior lumbar interbody fusion (ALIF) in restoring the main spinopelvic parameters, along with its potentials and limitations in correcting sagittal imbalance.

MATERIALS AND METHODS

The 2009 PRISMA flow chart was used to systematically review the literature; 27 papers were eventually selected. The following spinopelvic parameters were observed: pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), segmental lumbar lordosis (LLseg) and sagittal vertical axis (SVA). Papers reporting on hyperlordotic cages (HLC) were analysed separately. The indirect decompression potential of ALIF was also assessed. The clinical outcome was obtained by collecting visual analogue scale (VAS) for back and leg pain and Oswestry Disability Index (ODI) scores. Global fusion rate and main complications were collected.

RESULTS

PT, SS, LL, LLseg and SVA spinopelvic parameters all improved postoperatively by - 4.3 ± 5.2°, 3.9 ± 4.5°, 10.6 ± 12.5°, 6.7 ± 3.5° and 51.1 ± 44.8 mm, respectively. HLC were statistically more effective in restoring LL and LLseg (p < 0.05). Postoperative disc height, anterior disc height, posterior disc height and foraminal height, respectively, increased by 58.5%, 87.2%, 80.9% and 18.1%. Postoperative improvements were observed in VAS back and leg and ODI scores (p < 0.05). The global fusion rate was 94.5 ± 5.5%; the overall complication rate was 13%.

CONCLUSION

When managing sagittal imbalance, ALIF can be considered as a valid technique to achieve the correct spinopelvic parameters based on preoperative planning. This technique permits to obtain an optimal LL distribution and a solid anterior column support, with lower complications and higher fusion rates when compared to posterior osteotomies.

Anterior Lumbar Fusion: Differences in Patient Selection and Surgical Outcomes Between Neurosurgeons and Orthopaedic Surgeons

OBJECTIVE

Anterior lumbar fusion (ALF) is performed by both neurosurgeons and orthopaedic surgeons. The aim of this study was to determine differences between the 2 surgical subspecialties in terms of patient selection and postoperative outcomes after ALF.

METHODS

A retrospective cohort study of adult patients undergoing ALF in the American College of Surgeons National Surgical Quality Improvement Program database from 2010 to 2014 was performed. Univariate analyses were performed to identify differences in baseline patient demographics, comorbidities, operative characteristics, and 30-day postoperative outcomes between neurosurgery and orthopaedic surgery patients. Multivariate logistic regression analysis was used to determine whether surgical subspecialty was an independent risk factor for postoperative complications.

RESULTS

The study included 3182 patients, with 1629 (51.2%) neurosurgery patients and 1553 (48.8%) orthopaedic surgery patients. A greater proportion of neurosurgery patients were >65 years old, were being treated with preoperative steroids, had cardiac or pulmonary comorbidities, and had an American Society of Anesthesiologists classification III or higher. ALF procedures performed by neurosurgeons more frequently involved use of intervertebral devices and bone graft. On multivariate logistic regression analysis, ALF procedures performed by neurosurgeons were independently associated with a higher risk of reoperation (odds ratio = 1.61; 95% confidence interval, 1.02-2.56; P = 0.042) and urinary tract infection (odds ratio = 1.94; 95% confidence interval, 1.02-3.68; P = 0.043).

CONCLUSIONS

In addition to differences in baseline patient demographics and comorbidities and operative characteristics, ALF performed by neurosurgeons had a higher risk of 30-day reoperation and urinary tract infection compared with ALF performed by orthopaedic surgeons.

Anterior Lumbar Interbody Fusion With and Without an "Access Surgeon": A Systematic Review and Meta-analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

The aim of this study was to investigate the outcomes of anterior lumber interbody fusion (ALIF) with and without an "access surgeon."

SUMMARY OF BACKGROUND DATA

Anterior approaches for spine operations have become increasingly popular but may often involve unfamiliar anatomy and territory for spine surgeons, potentially placing the patient at risk to a greater proportion of approach-related complications. Thus, many spine surgeons require or prefer the assistance of an "access surgeon" to perform the exposure. However, there has been much debate about the necessity of an "access surgeon."

METHODS

A systematic search of six databases from inception to April 2016 was performed by two independent reviewers. Meta-analysis was used to pool overall rates, and compare the outcomes of ALIF with an access surgeon and without.

RESULTS

A total of 58 (8028 patients) studies were included in this meta-analysis. The overall intraoperative complications were similar with and without an "access surgeon." The overall pooled rate of arterial injuries [no access 0.44% vs. access 1.16%, odds ratio (OR) 2.67, P < 0.001], retrograde ejaculation (0.41% vs. 0.96%, OR 2.34, P = 0.005), and ileus (1.93% vs. 2.26%, OR 2.45, P < 0.001) was higher with an "access surgeon." However, the overall pooled rates of peritoneal injury (0.44% vs. 0.16%, OR 0.36, P = 0.034) and neurological injury (0.99% vs. 0.11%, OR 0.11, P < 0.001) were lower with an "access surgeon." Total postoperative complications (5.95% vs. 4.08%, OR 0.67, P < 0.001) were lower with an "access surgeon" along with prosthesis complications (1.59% vs. 0.89%, OR 0.56, P < 0.001) and reoperation rates (2.28% vs. 1.31%, OR 0.57, P < 0.001).

CONCLUSION

Compared with no access surgeon, the use of an access surgeon was associated with similar intraoperative complication rates, higher arterial injuries, retrograde ejaculation, ileus, and lower prosthesis complications, reoperation rates, and postoperative complications. In cases wherein exposure may be difficult, support from an "access surgeon" should be available.

LEVEL OF EVIDENCE

1.

Three cases of L4-5 Baastrup's disease due to L5-S1 spondylolytic spondylolisthesis

PURPOSE

Baastrup's disease is characterized by degeneration of spinous processes and interspinous soft tissue, which may cause spinal stenosis. Purpose of this article is to report the possible new cause of Baastrup's disease and result of surgical treatments.

METHODS

Authors treated three cases of Baastrup's disease on L4-L5 with L5-S1 spondylolytic listhesis. Conservative treatment did not relieve the pain; therefore, surgical treatments were planned according to each specific disease condition.

RESULTS

In one case, anterior lumbar interbody fusion of L5-S1 was performed, and after surgery, the size of epidural cyst on L4-L5 was decreased. L4-L5 bilateral laminectomy was performed to directly decompress posterior epidural cyst in a case with stable L5-S1 spondylolytic listhesis. In last case, facet joints and spinous process were removed by L5-S1 posterior lumbar interbody fusion (PLIF) surgery. After the surgery, patients' back and leg pain was improved and postoperative MRI revealed successful decompression of the spinal canal. Improvement in back and leg symptoms was noted at 12-month follow-up.

CONCLUSIONS

Baastrup's disease at the L4-L5 level may have developed from the instability caused by L5-S1 spondylolytic spondylolisthesis. Viable treatment options include the fusion of L5-S1 or a laminectomy at the L4-L5 level.

Iatrogenic Baastrup's Syndrome: A Potential Complication Following Anterior Interbody Lumbar Spinal Surgery

BACKGROUND

Baastrup's Syndrome is a condition that occurs when there is abnormal contact between two adjacent spinous processes resulting in back pain. An alteration in lumbar spinal alignment and/or adjacent segment compensatory motion is thought to be potential causative factors. The objective of this study was to present a case series of what appears to be iatrogenic Baastrup's Syndrome as a mid-to-late term complication following anterior lumbar interbody surgery.

METHODS

A retrospective chart review was performed of all patients undergoing anterior lumbar surgery for either fusion or disc replacement to determine the prevalence of Baastrup's Syndrome.

RESULTS

Over a 12-year period, 855 patients who had undergone an anterior approach for lumbar spine surgery were identified. Of them 8 patients with evidence of Baastrup's Syndrome were found; this demonstrated a prevalence of 0.9%. Diagnostic injection was a helpful clinical tool in confirming the diagnosis of iatrogenic Baastrup's Syndrome. The partial removal of the impinging spinous processes resulted in excellent clinical relief.

CONCLUSIONS

Iatrogenic Baastrup's Syndrome may be an iatrogenic result of anterior lumbar surgery in small group of patients. Spinous process excision is a suggested treatment option. Further studies are necessary to explore the above phenomenon. This study is a Level 3 retrospective case series.