Nonunion of Transpsoas Lateral Lumbar Interbody Fusion Using an Allograft: Clinical Assessment and Risk Factors

Pseudarthrosis risk factors in lumbar fusion: a systematic review and meta-analysis

This study presents a systematic literature review and meta-analysis of pseudarthrosis risk factors following lumbar fusion procedures. The odds ratio (OR) and 95% confidence interval (95% CI) were used for outcome measurements. The objective of this study was to identify the independent risk factors for pseudarthrosis after lumbar spinal fusion, which is crucial for mitigating morbidity and reoperation. Systematic searches in PubMed, Embase, and Scopus (1990-July 2021) were conducted using specific terms. The inclusion criteria included prospective and retrospective cohorts and case‒control series reporting ORs with 95% CIs from multivariate analysis. The quality assessment utilized the Newcastle-Ottawa scale. Meta-analysis, employing OR and 95% CI, assessed pseudarthrosis risk factors in lumbar fusion surgery, depicted in a forest plot. Of the 568 abstracts identified, 12 met the inclusion criteria (9 retrospective, 2006-2021). The 17 risk factors were categorized into clinical, radiographic, surgical, and bone turnover marker factors. The meta-analysis highlighted two significant clinical risk factors: age (95% CI 1.02-1.11; p = 0.005) and smoking (95% CI 1.68-5.44; p = 0.0002). The sole significant surgical risk factor was the number of fused levels (pooled OR 1.35; 95% CI 1.17-1.55; p < 0.0001). This study identified 17 risk factors for pseudarthrosis after lumbar fusion surgery, emphasizing age, smoking status, and the number of fusion levels. Prospective studies are warranted to explore additional risk factors and assess the impact of surgery and graft type.

Comparing Bone Fusion Rates Between Novel Unidirectional Porous Tricalcium Beta-Phosphate and Autologous Bone in Lumbar Lateral Interbody Fusion: A Two-Year Radiographic Outcome Study

This retrospective cohort study aims to examine the potential differences in bone fusion between autologous bone and artificial bone in the lumbar lateral interbody fusion at 2two years post-surgery. The bone fusions performed in 15 cases and at 34 intervertebral levels were compared to assess the differences between the artificial bone, Affinos® (Kuraray Co., Tokyo, Japan), and autogenous bone. Two years post-surgery, we evaluated computed tomography (CT) multi-planar reconstruction images in the coronal and sagittal planes. One year after surgery, out of the 24 windows, 17 (70.8%) windows transplanted with autologous bones showed bone fusion. Additionally, out of the 38 windows, 18 (47.4%) windows transplanted with Affinos® showed bone fusion. Two years post-surgery, out of the 24 windows, 19 (79.2%) windows transplanted with autologous bones showed bone fusion. Additionally, out of the 38 windows, 30 (79.0%) windows transplanted with Affinos® showed bone fusion, and no difference was observed in the fusion rate at two years post-surgery (P = 0.238). In cases using Affinos® for transplanted bone, the bone fusion rate increased between one and two years. The rate of bony fusion using Affinos® in lateral lumbar interbody fusion (LLIF) cages is at par with that of autologous bone grafts at two years post-surgery. Affinos® is a promising candidate for graft material in LLIF surgery.

Spontaneous facet joint fusion in patients following oblique lateral lumbar interbody fusion combined with lateral single screw-rod fixation: prevalence, characteristics and significance

PURPOSE

To explore the characteristics of spontaneous facet joint fusion (SFJF) in patients after oblique lateral lumbar interbody fusion combined with lateral single screw-rod fixation (OLIF-LSRF).

METHODS

We randomly selected 300 patients from 723 patients treated with OLIF-LSRF into a cross-sectional study based on the pilot study results. A novel fusion classification system was designed to evaluate the fusion status of the facet joints at three time points. Ultimately, the prevalence, characteristics, and significance of SFJF were analyzed.

RESULTS

A total of 265 (333 levels) qualified cases were included in our study. The novel classification for SFJF has excellent reliability (kappa > 0.75). The rate of SFJF was 15.20% (45/296 levels) at 3 months postoperatively, 31.34% (89/284 levels) at 6 months postoperatively, and 33.63% (112/333 levels) at the last follow-up. The circumferential fusion rate was 31.53% (105/333 levels) at the last follow-up. The location of SFJF was mostly on the right facet joint (P < 0.001), and the rate of SFJF increased significantly from 3 to 6 months after the operation (P < 0.001). The average age of patients with SFJF was older than that of patients without SFJF (P < 0.001). There was no significant difference in Visual Analog Scale or Oswestry Disability Index scores between patients with and without SFJF.

CONCLUSION

In the OLIF-LSRF procedure, SFJF occurs mostly at 3-6 months postoperatively, especially in elderly patients and at the right facet joint. OLIF-LSRF has the potential for circumferential fusion.

Radiological follow-up of the degenerated facet joints after lateral lumbar interbody fusion with percutaneous pedicle screw fixation: Focus on spontaneous facet joint fusion

BACKGROUND

Lateral lumbar interbody fusion (LLIF) is widely used in degenerative lumbar spine surgery. Previous studies of radiographic investigations after LLIF have assessed the anterior interbody fusion rate, the changes in the segmental lumbar lordosis, efficacy of indirect neural decompression, and remodeling of the ligamentum flavum hypertrophy and spinal canal dimension, and so on. The purpose of this study was to evaluate the radiological changes in the degenerated facet joints following LLIF with bilateral percutaneous pedicle screw (PPS) fixation, focusing on spontaneous fusion.

METHODS

We retrospectively analyzed 31 patients (79 surgical levels) who underwent two- or three-level LLIF with PPS fixation without direct posterior decompression and bone grafting. We assessed the fusion rate and characteristics of the facet joints' fusion process on the preoperative, immediately postoperative, 12-month, and at least 2-year computed tomography (CT) images. On average, the last follow-up CT was performed after 30.2 months. Multivariate logistic regression analysis investigated factors related to spontaneous facet joint fusion postoperatively.

RESULTS

The fusion rates of the interbody and facet joints were 32.9% (26/79) and 19.0% (15/79) after 12-months and 79.7% (63/79) and 58.2% (46/79) at the final CT follow-up, respectively. Of the 46 cases with spontaneous facet fusion, three cases fused posteriorly only. Concomitant anterior interbody fusion was seen in 43/46 (93.5%) cases. Facet fusion started in a ring shape from the outermost joint edges, exposing subchondral bone without cartilage covering, and progressed to the central thicker cartilage regions. Multivariate analysis established that concomitant anterior interbody fusion (adjusted odds ratio [aOR]: 12.10, P = 0.0035) and preoperative facet joint osteoarthritis of Weishaupt Grade ≧ 1 (aOR: 4.770, P = 0.0068) were significant contributing factors to postoperative spontaneous facet fusion.

CONCLUSIONS

Our study shows that spontaneous facet fusion frequently occurs after LLIF and may be an indicator of the inherent structural stability of the LLIF construct.

Comparison of clinical and radiological outcomes of local morselized bone grafts and structural iliac bone grafts in the treatment of lumbar tuberculosis with posterior-only surgery

Background

Many surgeons have reported results similar to those of anterior debridement and bone grafting in treating spinal tuberculosis in the lumbar region using only a posterior approach. However, there is still no consensus regarding bone graft methods. This study aims to compare the clinical and radiological outcomes of morselized versus structural iliac bone grafts in the treatment of lumbar tuberculosis via one-stage posterior surgery.

Methods

A retrospective study was performed with 82 patients with lumbar tuberculosis who had undergone posterior-only debridement, bone grafting, and instrumentation between January 2014 and June 2018. Morselized bone grafts were used in 43 patients, whereas structural iliac bone grafts were used in 39 patients. The clinical data and imaging results of the patients were compared between the two groups to evaluate the clinical effects of the two types of grafts.

Results

The operation time, blood loss and hospital stay values in the morselized bone group were significantly lower than those in the structural iliac bone group (p < 0.05). No significant differences were observed with respect to erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Cobb angle, or improvement of neurological function between the two groups. The VAS pain scores for low back and leg pain decreased significantly after the operation (p < 0.05). However, postoperatively, the VAS score was higher in the structural iliac bone group than in the morselized bone group, and there was no significant difference at the last follow-up between the two groups (p > 0.05). Bone fusion was achieved in 41 patients (95%) in the morselized bone group and 38 patients (97%) in the structural iliac bone group. There was no significant difference between the fusion rates of the two groups (p > 0.05).

Conclusion

The two graft techniques achieved comparable clinical outcomes in lumbar spinal tuberculosis treatment. However, the morselized bone graft was more beneficial in terms of reducing surgical trauma and postoperative complications.

[Research progress of spontaneous facet fusion after lumbar spine surgery]

OBJECTIVE

To summarize the research progress on spontaneous facet fusion (SFF) after lumbar spine surgery, and provide reference for further research on SFF.

METHODS

The definition, development, clinical significance, and related influence factors of SFF were throughout reviewed by referring to relevant domestic and foreign literature in recent years.

RESULTS

SFF is a phenomenon of joint space disappearance and fusion of upper and lower articular processes, which starts in a ring shape from the outermost edges to the central regions. Currently reported SFF occurred after posterior lumbar pedicle screw fixation. SFF may increase the stability of surgical segments and relieve clinical symptoms of patients. SFF is closely related to the method of lumbar internal fixation, facet osteoarthritis, interbody fusion, age, body mass index, type B fracture (according to AO classification), and the operative segment.

CONCLUSION

Most reported SFF occur after posterior lumbar pedicle screw fixation, which can increase lumbar stability, but the mechanism and influencing factors remain to be further clarified.

Unintentional Fusion in Preserved Facet Joints without Bone Grafting after Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion

Introduction

A percutaneous endoscopic transforaminal lumbar interbody fusion (PETLIF) procedure has been previously developed. During postoperative follow-up, in some patients, bone fusion occurred between opened facet joints, despite not having bone grafting in the facet joints. Here, we investigated facet fusion's frequency and tendencies following PETLIF.

Methods

A retrospective analysis was conducted on a prospectively collected, nonrandomized series of patients. Forty-two patients (6 males and 36 females, average age: 69.9 years) who underwent single-level PETLIF at our hospital from February 2016 to March 2019 were included in this study. Patients were assessed with lumbar X-ray images and computed tomography (CT) prior to, immediately after, and 1 year after surgery.

Results

Pseudarthrosis was not observed in any patients, and facet fusion was observed in 26 of 42 post-PETLIF patients (61.9%) by CT 1 year postoperatively. The average interfacet distance increased from 1.3 mm preoperatively to 4.5 mm postoperatively, and facet fusion was observed under the opened conditions of 3.8 mm at 1 year. Segmental lordotic angle of the fusion segment in the lumbar X-ray images was significantly larger in the facet fusion subgroup prior to surgery, immediately following surgery, and 1 year after surgery compared to the facet non-fusion group (p=0.02, p<0.01, p=0.01, respectively). There were no significant differences in patient background, correction loss of segmental lordosis, interfacet distance, or clinical score between the facet fusion and facet non-fusion subgroups.

Conclusions

Facet fusion was achieved over time within the facet joints that were opened through indirect decompression after PETLIF. We hypothesized that the preserved facet joints potentially became the base bed for spontaneous bone fusion due to the preserved facet joint capsule and surrounding soft tissue, which maintained cranio-caudal facet traffic and blood circulation in the facet joints. The complete preservation of the facet joints was a key advantage of minimally invasive lumbar interbody fusion procedures.

Level of evidence

Level III

Coronal Plane Gap Increases Postoperative Pseudoarthrosis after Lateral Interbody Fusion for Adult Spinal Deformity

Study Design

This is a retrospective study.

Purpose

This study aims to evaluate the risk factor associated with pseudoarthrosis after placement of lateral interbody fusion (LIF) cages for adult spinal deformity (ASD) treatment.

Overview of Literature

LIF technique is widely used for ASD correction. Furthermore, pseudoarthrosis is a major complication of fusion surgery required for revision surgery.

Methods

This study included 42 patients with ASD (two men and 40 women; 112 segments; mean, 68.5±8.4 years; and mean follow-up, 31.6±17.0 months) who underwent LIF and posterior correction surgery. The concave slot of the LIF cage was filled with an autologous iliac crest bone graft (IBG), and the convex slot with a porous hydroxyapatite/collagen (HAp/Col) composite was soaked with bone marrow aspirate. Endplate injury, the gap between vertebral endplate and cage in the coronal or sagittal plane, and fusion status were evaluated using computed tomography multiplanar reconstruction at 12 months after surgery. Moreover, the associated risk factors for pseudoarthrosis were analyzed.

Results

Fusion at LIF segments were observed in 71.4% segments at 12 months after surgery. Fusion on the concave slot (autologous IBG side), convex slot (porous HAp/Col composite side), and both concave and convex slots were observed in 66.1%, 37.5%, and 36.6% of patients, respectively. Moreover, pseudoarthrosis was observed in 28.6% at 12 months after surgery. Consequently, logistic regression analysis of the fusion at the LIF segment revealed that the gap between the LIF cage and endplate in the coronal plane (p=0.030; odds ratio, 0.183; 95% confidence interval, 0.030–0.183) was significantly associated with pseudoarthrosis at the LIF segments.

Conclusions

ASD surgery fusion rate using LIF cages was 71.4% at 12 months after surgery. The fusion rate was higher on the concave slot filled with autologous IBG than on the convex slot filled with a porous HAp/Col composite. The gap in the coronal plane was a risk factor for pseudoarthrosis at the LIF segment.