Prashanth J. Rao

Lumbar interbody fusion: techniques, indications and comparison of interbody fusion options including PLIF, TLIF, MI-TLIF, OLIF/ATP, LLIF and ALIF.

Degenerative disc and facet joint disease of the lumbar spine is common in the ageing population, and is one of the most frequent causes of disability. Lumbar spondylosis may result in mechanical back pain, radicular and claudicant symptoms, reduced mobility and poor quality of life. Surgical interbody fusion of degenerative levels is an effective treatment option to stabilize the painful motion segment, and may provide indirect decompression of the neural elements, restore lordosis and correct deformity. The surgical options for interbody fusion of the lumbar spine include: posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), minimally invasive transforaminal lumbar interbody fusion (MI-TLIF), oblique lumbar interbody fusion/anterior to psoas (OLIF/ATP), lateral lumbar interbody fusion (LLIF) and anterior lumbar interbody fusion (ALIF). The indications may include: discogenic/facetogenic low back pain, neurogenic claudication, radiculopathy due to foraminal stenosis, lumbar degenerative spinal deformity including symptomatic spondylolisthesis and degenerative scoliosis. In general, traditional posterior approaches are frequently used with acceptable fusion rates and low complication rates, however they are limited by thecal sac and nerve root retraction, along with iatrogenic injury to the paraspinal musculature and disruption of the posterior tension band. Minimally invasive (MIS) posterior approaches have evolved in an attempt to reduce approach related complications. Anterior approaches avoid the spinal canal, cauda equina and nerve roots, however have issues with approach related abdominal and vascular complications. In addition, lateral and OLIF techniques have potential risks to the lumbar plexus and psoas muscle. The present study aims firstly to comprehensively review the available literature and evidence for different lumbar interbody fusion (LIF) techniques. Secondly, we propose a set of recommendations and guidelines for the indications for interbody fusion options. Thirdly, this article provides a description of each approach, and illustrates the potential benefits and disadvantages of each technique with reference to indication and spine level performed.

Spine Interbody Implants: Material Selection and Modification, Functionalization and Bioactivation of Surfaces to Improve Osseointegration

The clinical outcome of lumbar spinal fusion is correlated with achievement of bony fusion. Improving interbody implant bone on‐growth and in‐growth may enhance fusion, limiting pseudoarthrosis, stress shielding, subsidence and implant failure. Polyetheretherketone (PEEK) and titanium (Ti) are commonly selected for interbody spacer construction. Although these materials have desirable biocompatibility and mechanical properties, they require further modification to support osseointegration. Reports of extensive research on this topic are available in biomaterial‐centric published reports; however, there are few clinical studies concerning surface modification of interbody spinal implants. The current article focuses on surface modifications aimed at fostering osseointegration from a clinicians point of view. Surface modification of Ti by creating rougher surfaces, modifying its surface topography (macro and nano), physical and chemical treatment and creating a porous material with high interconnectivity can improve its osseointegrative potential and bioactivity. Coating the surface with osteoconductive materials like hydroxyapatite (HA) can improve osseointegration. Because PEEK spacers are relatively inert, creating a composite by adding Ti or osteoconductive materials like HA can improve osseointegration. In addition, PEEK may be coated with Ti, effectively bio‐activating the coating.

Outcomes of anterior lumbar interbody fusion surgery based on indication: a prospective study.

BACKGROUND There is limited information on clinical outcomes after anterior lumbar interbody fusion (ALIF) based on the indications for surgery. OBJECTIVE To compare the clinical and radiological outcomes of ALIF for each surgical indication. METHODS This prospective clinical study included 125 patients who underwent ALIF over a 2-year period. The patients were evaluated preoperatively and postoperatively. Outcome measures included the Short Form-12, Oswestry Disability Index, Visual Analog Scale, and Patient Satisfaction Index. RESULTS After a mean follow-up of 20 months, the clinical condition of the patients was significantly better than their preoperative status across all indications. A total of 108 patients had a Patient Satisfaction Index score of 1 or 2, indicating a successful clinical outcome in 86%. Patients with degenerative disk disease (with and without radiculopathy), spondylolisthesis, and scoliosis had the best clinical response to ALIF, with statistically significant improvement in the Short Form-12, Oswestry Disability Index, and Visual Analog Scale. Failed posterior fusion and adjacent segment disease showed statistically significant improvement in all of these clinical outcome scores, although the mean changes in the Short Form-12 Mental Component Summary, Oswestry Disability Index, and Visual Analog Scale (back pain) were lower. The overall radiological fusion rate was 94.4%. Superior radiological outcomes (fusion >90%) were observed in patients with degenerative disk disease (with and without radiculopathy), spondylolisthesis, and failed posterior fusion, whereas in adjacent segment disease, it was 80%. CONCLUSION ALIF is an effective treatment for degenerative disk disease (with and without radiculopathy) and spondylolisthesis. Although results were promising for scoliosis, failed posterior fusion, and adjacent segment disease, further studies are necessary to establish the effectiveness of ALIF in these conditions.

Indications for Anterior Lumbar Interbody Fusion

Anterior lumbar interbody fusion (ALIF) has become a widely recognized surgical technique for degenerative pathology of the lumbar spine. Spinal fusion has evolved dramatically ever since the first successful internal fixation by Hadra in 1891 who used a posterior approach to wire adjacent cervical vertebrae in the treatment of fracture‐dislocation. Advancements were made to reduce morbidity including bone grafting substitutes, metallic hardware instrumentation and improved surgical technique. The controversy regarding which surgical approach is best for treating various pathologies of the lumbar spine still exists. Despite being an established treatment modality, current indications of ALIF are yet to be clearly defined in the literature. This article discusses the current literature on indications on ALIF surgery.

Percutaneous versus open pedicle screw fixation for treatment of thoracolumbar fractures: Systematic review and meta-analysis of comparative studies

BACKGROUND The main aims of managing thoracolumbar fractures involve stabilization of traumatized regions, to promote vertebral healing or segmental fusion. Recently, percutaneous pedicle screw fixation has evolved as an alternative approach for the treatment of thoracolumbar fractures, aiming to minimize soft tissue injury and perioperative morbidity. A systematic review and meta-analysis was conducted to compare outcomes of percutaneous versus open pedicle screw fixation for thoracolumbar fractures. METHODS Relevant articles were identified from six electronic databases from their inception to December 2014. RESULTS From 12 relevant studies identified, 279 patients undergoing percutaneous fixation were compared with 340 open fixation procedures. Operative duration was significantly shorter in the percutaneous group by 19 min (P = 0.0002). The percutaneous approach was also associated with shorter hospital stay by 5.7 days (P = 0.0007). Whilst there was no difference in screw malpositioning (RR, 0.77; 95% CI, 0.33, 1.83; P = 0.56), the percutaneous approach had lower rates of infections (RR, 0.36; 95% CI, 0.13, 1.00; P = 0.05), and superior visual analogue scale clinical outcomes (P = 0.001). No difference was found between the groups in terms of postoperative Cobb angle (P = 0.22), postoperative body angle (P = 0.66), and postoperative anterior body height (P = 0.19). CONCLUSIONS The percutaneous approach was associated with shorter operative duration and hospital stay, reduced intraoperative blood loss and reduced infection rates. Given the lack of robust clinical evidence, these findings warrant verification in large prospective registries and randomized trials.

Approach-Related Complications of Anterior Lumbar Interbody Fusion: Results of a Combined Spine and Vascular Surgical Team

Study Design Retrospective analysis of prospectively collected cohort data. Objective Anterior lumbar interbody fusion (ALIF) is a commonly performed procedure for the treatment of degenerative diseases of the lumbar spine. Detailed and comprehensive descriptions of intra- and postoperative complications of ALIF are surprisingly limited in the literature. In this report, we describe our experience with a team model for ALIF and report all complications occurring in our patient series. Methods Patients were prospectively enrolled between January 2009 and January 2013 by a combined spine surgeon and vascular surgeon team. All patients underwent an open ALIF using an anterior approach to the lumbosacral spine. Results From the 227 ALIF cases, mean operative blood loss was 103 mL, ranging from 30 to 900 mL. Mean operative time was 78 minutes. The average length of stay was 5.2 days. Intraoperative vascular injury requiring primary repair with suturing occurred in 15 patients (6.6%). There were 2 cases of postoperative retroperitoneal hematoma. Three patients (1.3%) had incisional hernia requiring revision surgery; 7 (3.1%) patients had prolonged ileus (>7 days) managed conservatively. Four patients described retrograde ejaculation. Sympathetic dysfunction occurred in 15 (6.6%) patients. There were 5 (2.2%) cases of superficial wound infection treated with oral antibiotics, with no deep wound infections requiring reoperation or intravenous therapy. There were no mortalities in this series. Conclusions ALIF is a safe procedure when performed by a combined vascular surgeon and spine surgeon team with acceptably low complication rates. Our series confirms that the team approach results in short operative times and length of stay, with rapid control of intraoperative vessel injury and low overall blood loss.

Indirect foraminal decompression after anterior lumbar interbody fusion: a prospective radiographic study using a new pedicle-to-pedicle technique

BACKGROUND CONTEXT A frequently quoted advantage of anterior lumbar interbody fusion (ALIF) is indirect foraminal decompression, although there are few studies substantiating this statement. Also, there are no clinical studies using a standardized method to measure the foraminal area (FA) and the correlation with disc height (DH) parameters. This study is proposed to measure the degree of indirect foraminal decompression radiologically using a standardized method and correlate with the intervertebral disc parameters. PURPOSE To standardize the foramen measurement technique. To measure indirect neural foraminal decompression in surgically operated patients after ALIF using radiographic measurement and elucidate factors affecting foraminal restoration. STUDY DESIGN A prospective cohort study. PATIENT SAMPLE A continuous cohort of patients undergoing ALIF surgery. OUTCOME MEASURES It included FA, foraminal height (FH), and foraminal width. METHODS This is a prospective analysis of a single surgeon series of consecutive patients undergoing an ALIF from 2011 to 2013. Pre- and postoperative computed tomography scans were used to obtain a standardized foramen snapshot using the pedicle-to-pedicle (P-P) technique, and measurements were obtained using image j software. Radiologic parameters such as DH, local disc angle (LDA), and lumbar lordosis (LL) were measured using radiographs and Surgimap software. RESULTS One-hundred forty patients with 184 levels were operated. Anterior lumbar interbody fusion resulted in a statistically significant (p<.01) improvement in foraminal dimensions (area=67%, height=21%, and width=38%). Other parameters also significantly improved, including anterior DH (90%), posterior DH (77%), LDA, and LL (6%). Posterior DH correlated significantly with FH improvement. Statistically, the P-P technique presented with high intra- and interclass reliabilities. CONCLUSIONS Anterior lumbar interbody fusion results in significant indirect foraminal decompression based on the new P-P technique. Posterior DH is a significant factor in the restoration of the FH.

Lateral lumbar interbody fusion for sagittal balance correction and spinal deformity.

We conducted a systematic review to assess the safety and clinical and radiological outcomes of the recently introduced, direct or extreme lateral lumbar interbody fusion (XLIF) approach for degenerative spinal deformity disorders. Open fusion and instrumentation has traditionally been the mainstay treatment. However, in recent years, there has been an increasing emphasis on minimally invasive fusion and instrumentation techniques, with the aim of minimizing surgical trauma and blood loss and reducing hospitalization. From six electronic databases, 21 eligible studies were included for review. The pooled weighted average mean of preoperative visual analogue scale (VAS) pain scores was 6.8, compared to a postoperative VAS score of 2.9 (p<0.0001). The weighted average preoperative and postoperative coronal segmental Cobb angles were 3.6 and 1.1°, respectively. The weighted average preoperative and postoperative coronal regional Cobb angles were 19.1 and 10.0°, respectively. Regional lumbar lordosis also significantly improved from 35.8 to 43.3°. Sagittal alignment was comparable pre- and postoperatively (34 mm versus 35.1mm). The weighted average operative duration was 125.6 minutes, whilst the mean estimated blood loss was 155 mL. The weighted average hospitalization length was 3.6 days. Whilst the available data is limited, minimally invasive XLIF procedures appear to be a promising alternative for the treatment of scoliosis, with improved functional VAS and Oswestry disability index outcomes and restored coronal deformity. Future comparative studies are warranted to assess the long term benefits and risks of XLIF compared to anterior and posterior procedures.

Stand-alone anterior lumbar interbody fusion for treatment of degenerative spondylolisthesis.

We sought to evaluate the clinical and radiologic efficacy of stand-alone anterior lumbar interbody fusion (ALIF) for low grade degenerative spondylolisthesis, the favoured surgical management approach at our institution. The optimal approach for surgical management of spondylolisthesis remains contentious. We performed a prospective analysis of all consecutive patients with low grade lumbar spondylolisthesis who underwent ALIF between 2009 and 2013 by a single surgeon (n=27). The mean age was 64.9 years with a male to female ratio of 14:13. There were 32 levels operated and the average preoperative spondylolisthesis was 14.8%, which reduced to 6.4% postoperatively and 9.4% at the latest follow-up (p=0001). Postoperative disc height was increased to 175% of preoperative values and was statistically significant (p<0.001) and remained improved with an overall change of 139% at the latest follow-up. The radiological fusion rate was 91%. The 12-Item Short Form Health Survey (SF-12) mental and physical component summary improved from 31.7 to 43.0 (p=0.007) and from 35.4 to 51.7 (p=0.0026), respectively. The mean visual analogue scale pain score improved from 7.6 to 2.2 (p<0.001), and the mean Oswestry disability index improved from 56.9 to 17.8% (p<0.0001). The overall clinical success rate was 93%. The posterior disc height correlated with spondylolisthesis reduction (p=0.04) and the only clinical factor affecting reduction was body mass index (p=0.04). The present study provides encouraging short term results for stand-alone ALIF as a procedure for low grade lumbar degenerative spondylolisthesis. Future studies should include adequately powered, prospective, multicentre registry studies with long term follow-up to allow a better assessment of the relative benefits and risks.

Can bacterial infection by low virulent organisms be a plausible cause for symptomatic disc degeneration? A systematic review.

Study Design. Systematic review and meta-analysis. Objective. To review and assess the current evidence from the literature on the potential association between disc infection with the development of symptomatic degenerative disc disease. Summary of Background Data. The potential relationship between disc infection– and disc degeneration–related symptoms remains controversial, with contradictory evidence available in the literature. Several studies have demonstrated the presence of infected extruded nucleus tissue from first-time disc herniations, implicating the role of disc microbial infection as a pathway for disc degeneration. In contrast, other studies reported very low prevalence of bacterial infection in samples from patients with sciatica, quoting contamination as the predominant source. To summarize the available evidence to date, a systematic review and meta-analysis was conducted. Methods. A comprehensive search from 6 electronic databases was performed for studies investigating the potential relationship between disc infection as a cause for degenerative disc disease and symptomatic neck/back pain or radiculopathy. Random-effects meta-analysis of proportions and odds ratio with 95% confidence intervals was used to pool the available evidence. Results. Nine relevant studies involving 602 patients with degenerative disc disease or pain were identified. From 6 studies supporting the role of infection in the pathophysiology of disc degeneration, the pooled infection prevalence was 45.2% (34.5%–56.0%). Overall pooled prevalence in all studies was 36.2% (24.7%–47.7%). Proportion of disc infections was higher in patients with symptomatic disc disease than in patients without (37.4% vs. 5.9%; odds ratio, 6.1; 95% confidence intervals, 1.426–25.901). The majority of infections were due to Propionibacterium acnes in 59.6% (43.2%–76.1%). Conclusion. From the limited evidence available, the possibility that disc infection may be linked with disc degeneration should not be ruled out. There is a need to investigate this further through larger, adequately powered multi-institutional studies with contaminant arm to control for specimen contamination. Level of Evidence: 2