Pseudarthrosis of the Cervical Spine

18F-Naf PET/CT in pseudarthrosis after anterior cervical discectomy and fusion

BACKGROUND CONTEXT

Pseudarthrosis is a well-known cause of persistent or recurrent pain after anterior cervical discectomy and fusion (ACDF). Numerous radiographic criteria to determine the fusion status has been described in the literature, but their accuracies in clinical practice vary considerably and no 1 single method has proved superior. Fluorine-18 sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT), depicting osteoblastic activity, might be useful to identify pseudarthrosis after ACDF.

PURPOSE

To investigate the ability of 18F-NaF PET/CT to identify pseudarthrosis after ACDF using surgical revision as the reference standard.

STUDY DESIGN

Retrospective observational study.

PATIENTS SAMPLE

A total of 30 patients consisting of 40 surgical levels.

OUTCOME MEASURES

For each level, the presence or absence of intragraft uptake (InGU) and extragraft uptake (ExGU) were recorded, as well as adjacent segment uptake (ASU). CT part of the scan was rated as "fused" or "nonfused." Results were correlated to the gold-standard of revision surgery.

METHODS

We retrospectively included consecutive patients who underwent revision surgery for suspicion of symptomatic pseudarthrosis after ACDF following 18F-NaF PET/CT performed between July 2019 and march 2023. 18F-NaF PET/CT results were compared with the gold standard of surgical evaluation of the stability of the fusion material. All patients underwent a systematic CT scan to evaluate the success of revision surgery 1 year postoperatively. We also investigated whether some patients underwent a repeated 18F-NaF PET/CT for persistent or recurrent pain after revision surgery.

RESULTS

Revision surgery demonstrated pseudarthrosis in 37 levels (93%) and excluded pseudarthrosis in 3 levels (7%). In the pseudarthrosis group (n=37), InGU was observed in all levels (100%) while ExGU was present in only 10 levels (27%). Fifteen levels (41%) with confirmed pseudarthrosis were rated as "fused" on CT scan preoperatively. In the non-pseudarthrosis group (n=3), InGU was observed in 2 levels (67%) while ExGU was never present. Two levels (67%) were rated as "fused" on fusion CT scan. One year postoperatively, fusion was successfully achieved on CT scan in 39 levels (98%). Seven patients (consisting of 8 levels) had been subsequently re-explored by 18F-NaF PET/CT for persistent or recurrent pain following revision surgery. PET/CT did not reveal any uptake (InGU or ExGU) in 7 levels, rated as "fused" on follow-up CT scan. PET/CT showed InGU in the only level rated as "nonfused" on CT scan.

CONCLUSIONS

18F NaF PET/CT may be a useful adjunctive diagnostic tool to detect pseudarthrosis after ACDF surgery, especially in case of high clinical suspicion with standard conventional imaging not suggestive of non-union. In our cohort, all levels (100%) with confirmed pseudarthrosis on revision surgery demonstrated InGU on PET/CT, while 41% of these levels were rated as "fused" on CT scan preoperatively. 18F NaF PET/CT might also be helpful after revision surgery to rule out re-pseudarthrosis and identify the pain generator. These promising data need to be confirmed in larger prospective studies.

Impact of the Disc Vacuum Phenomenon on Surgical Outcomes in Lumbar Spinal Stenosis: A Comparative Study between Endoscopic Decompression and Minimally Invasive Oblique Lateral Interbody Fusion

Objective: This study investigated the influence of the vacuum phenomenon (VP) on surgical outcomes in patients with lumbar spinal stenosis, comparing minimally invasive oblique lateral interbody fusion (MIS OLIF) and endoscopic decompression. Methods: A cohort of 110 patients diagnosed with lumbar spinal stenosis underwent either endoscopic decompression or MIS OLIF. Patients were classified into two groups based on the presence or absence of the VP on preoperative CT scans, non-VP (n = 42) and VP (n = 68). Radiologic and clinical outcomes, including back and leg pain assessed using the visual analogue scale (VAS), the Oswestry Disability Index (ODI), and the EuroQol-5 Dimension (Eq5D), were compared pre- and postoperatively over a 2-year follow-up period. Results: Preoperatively, the VP group exhibited significantly greater leg pain (p = 0.010), while no significant differences were observed in back pain or the ODI between the groups. In the non-VP group, decompression and fusion yielded similar outcomes, with decompression showing a better ODI score at 1 month (p = 0.018). In contrast, in the VP group, patients who underwent fusion showed significantly improved long-term leg pain outcomes compared to those who underwent decompression at both 1-year (p = 0.042) and 2-year (p = 0.017) follow-ups. Conclusions: The VP may indicate segmental instability and may play a role in the persistence of radiculopathy. Fusion surgery appears to offer better long-term relief in patients with the VP, whereas decompression alone is a viable option in non-VP cases. These findings suggest that the VP may be a useful factor in guiding surgical decision-making.

Novel Calcium Phosphate Promotes Interbody Bony Fusion in a Porcine Anterior Cervical Discectomy and Fusion Model

STUDY DESIGN

Experimental porcine anterior cervical discectomy and fusion (ACDF) model: a proof-of-concept study.

OBJECTIVE

The effect of monetite synthetic bone graft (SBG) containing calcium pyrophosphate and β-tricalcium phosphate on cervical spinal fusion in a noninstrumented two-level large animal model.

SUMMARY OF BACKGROUND DATA

ACDF is the gold standard surgical technique for the treatment of degenerative cervical spinal diseases. However, pseudarthrosis associated with increased patient morbidity occurs in ∼2.6% of the surgeries. SBG may enhance bony fusion and subsequently decrease the risk of pseudarthrosis. Recent studies on monetite-based SBGs for use in large cranial defects in humans have shown promising bone healing results, necessitating further investigation of their use in cervical spinal fusion.

MATERIALS AND METHODS

Four adult female Danish Göttingen minipigs received partial cervical anterior discectomy and intervertebral defects at an upper and lower level. One defect was filled with SBG, and the other was left empty. Bony fusion was evaluated using computed tomography (CT) at three-month intervals for 12 months. Fifteen months postsurgery, the animals were euthanized for further ex vivo qualitative histopathologic and micro-CT evaluations. Fusion rates were compared using the Fisher exact test at each time point.

RESULTS

Increased interbody bony fusion rates were observed at SBG levels (4/4) compared with control levels (0/4) evaluated by CT at 6 and 9 months postsurgery ( P =0.029). Fusion was observed at all SBG levels 12 months postsurgery and at only one control level. Histopathologic evaluation confirmed high-quality interbody bony fusion at all SBG levels and fusion by spondylosis at one control level.

CONCLUSION

This proof-of-concept study provides preliminary evidence of a novel, calcium pyrophosphate-containing, and β-tricalcium phosphate-containing monetite SBG that promotes bony fusion compared with a negative control in a clinically relevant porcine model of ACDF.

Outcomes Following Anterior Cervical Discectomy and Fusion in Patients With Ehlers-Danlos Syndrome

STUDY DESIGN

Retrospective database analysis.

OBJECTIVES

To study postoperative complication rates following anterior cervical discectomy and fusion (ACDF) in patients with Ehlers-Danlos syndrome (EDS) compared with patients without EDS.

METHODS

The Mariner database was utilized to identify patients with EDS undergoing one or two level anterior cervical discectomy and fusion (ACDF). Postoperative short-term outcomes assessed included medical complications, readmissions, and ED-visits within 90 days of surgery. Additionally, surgical complications including wound complications, surgical site infection, one- and two-year anterior revision along with posterior revision, pseudarthrosis, and hardware failure within 2 years were assessed. Multivariate logistic regression was used to adjust for demographic variables, comorbidities and number of levels operated on.

RESULTS

The present study identified 533 patients in the EDS group and 2634 patients in the matched control group. EDS patients undergoing ACDF are at an increased risk for 90-day major medical complications (OR 3.31; P < .001). EDS patients were also found to be associated with surgical complications including wound complications (OR 2.94; P < .001), surgical site infection (OR 8.60; P < .001) within 90 days, pseudarthrosis (OR 2.33; P < .001), instrument failure (OR 4.03; P < .001), anterior revision (OR 22.87; P < .001), and posterior revision (OR 3.17; P < .001) within 2 years.

CONCLUSIONS

EDS is associated with higher rates of both medical and surgical complications following ACDF. Spine surgeons should be cognizant of the increased risks in this population to provide appropriate preoperative counseling and enhanced perioperative medical management.

Perioperative and safety outcomes following tissue-sparing posterior cervical fusion to revise a pseudarthrosis: A multicenter retrospective review of 150 cases

Background

Posterior cervical fusion (PCF) with lateral mass screws is a favorable treatment option to revise a symptomatic pseudarthrosis due to reliable rates of arthrodesis; however, this technique introduces elevated risk for wound infection and hospital readmission. A tissue-sparing PCF approach involving facet fixation instrumentation reduces the rates of postoperative complications while stabilizing the symptomatic level to achieve arthrodesis; however, these outcomes have been limited to small study cohorts from individual surgeons commonly with mixed indications for treatment.

Materials and Methods

One hundred and fifty cases were identified from a retrospective chart review performed by seven surgeons across six sites in the United States. All cases involved PCF revision for a pseudarthrosis at one or more levels from C3 to C7 following anterior cervical discectomy and fusion (ACDF). PCF was performed using a tissue-sparing technique with facet instrumentation. Cases involving additional supplemental fixation such as lateral mass screws, rods, wires, or other hardware were excluded. Demographics, operative notes, postoperative complications, hospital readmission, and subsequent surgical interventions were summarized as an entire cohort and according to the following risk factors: age, sex, number of levels revised, body mass index (BMI), and history of nicotine use.

Results

The average age of patients at the time of PCF revision was 55 ± 11 years and 63% were female. The average BMI was 29 ± 6 kg/m2 and 19% reported a history of nicotine use. Postoperative follow-up visits were available with a median of 68 days (interquartile range = 41-209 days) from revision PCF. There were 91 1-level, 49 2-level, 8 3-level, and 2 4±-level PCF revision cases. The mean operative duration was 52 ± 3 min with an estimated blood loss of 14 ± 1.5cc. Participants were discharged an average of 1 ± 0.05 days following surgery. Multilevel treatment resulted in longer procedure times (single = 45 min, multi = 59 min, P = 0.01) but did not impact estimated blood loss (P = 0.94). Total nights in the hospital increased by 0.2 nights with multilevel treatment (P = 0.01). Sex, age, nicotine history, and BMI had no effect on recorded perioperative outcomes. There was one instance of rehospitalization due to deep-vein thrombosis, one instance of persistent pseudarthrosis at the revised level treated with ACDF, and four instances of adjacent segment disease. In patients initially treated with multilevel ACDF, revisions occurred most commonly on the caudal level (48% of revised levels), followed by the cranial (43%), and least often in the middle level (9%).

Conclusions

This chart review of perioperative and safety outcomes provides evidence in support of tissue-sparing PCF with facet instrumentation as a treatment for symptomatic pseudarthrosis after ACDF. The most common locations requiring revision were the caudal and cranial levels. Operative duration and estimated blood loss were favorable when compared to open alternatives. There were no instances of postoperative wound infection, and the majority of patients were discharged the day following surgery.

The incidence of reoperation for pseudarthrosis after cervical spine surgery

INTRODUCTION

Pseudarthrosis after cervical spine surgery represents an underreported and challenging complication. Using a large multi-center surgical database, we sought to: (1) report the incidence of cervical pseudarthrosis, (2) evaluate changes in rates of cervical pseudarthrosis, and (3) describe risk factors for suboptimal outcomes after cervical pseudarthrosis surgery.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database from 2012 to 2019 was used. The primary outcome was occurrence of a cervical fusion procedure with a prior diagnosis of pseudarthrosis. Fusion for pseudarthrosis was divided into anterior and posterior approaches. Post-operative complications were classified as major or minor. Prolonged LOS was defined as exceeding the 75th percentile for total hospital stay.

RESULTS

A total of 780 patients underwent cervical fusion for pseudarthrosis, and a significant increase in rates of surgery for pseudarthrosis was seen (0.25-1.2%, p < 0.001). The majority of cervical pseudarthrosis was treated with a posterior approach (66.5%). Postoperatively, 38 (4.9%) patients suffered a complication and 247 (31.7%) had a prolonged LOS. The three strongest risk factors for complications and extended LOS were > 10% weight loss preoperatively, congestive heart failure, and pre-operative bleeding disorder.

CONCLUSION

Results from a large multi-center national database revealed that surgery to treat cervical pseudarthrosis has increased from 2012 to 2019. Most pseudarthrosis was treated with a posterior approach. Reoperation to treat cervical pseudarthrosis carried risk, with 5% having complications and 32% having an extended LOS. These results lay the groundwork for a future prospective study to discern the true incidence of cervical pseudarthrosis and how to best avoid its occurrence.

Comparison of Outcomes in Patients with Cervical Spine Metastasis After Different Surgical Approaches: A Single-Center Experience

OBJECTIVE

In patients undergoing cervical spine surgery for metastatic spine disease, we sought to 1) compare perioperative and oncologic outcomes among 3 different operative approaches, 2) report fusion rates, and 3) compare different types of anterior vertebral body replacement.

METHODS

A single-center retrospective cohort study of patients undergoing extradural cervical/cervicothoracic spine metastasis surgery between February 2010 and January 2021 was conducted. Operative approaches were anterior-alone, posterior-alone, or combined anterior-posterior, and the grafts/cages used in the anterior fusions were cortical allografts, static cages, or expandable cages. All cages were filled with autograft/allograft. Outcomes included perioperative/postoperative variables, along with fusion rates, functional status, local recurrence (LR), and overall survival (OS).

RESULTS

Sixty-one patients underwent cervical spine surgery for metastatic disease, including 11 anterior (18.0%), 28 posterior (45.9%), and 22 combined (36.1%). New postoperative neurologic deficit was the highest in the anterior approach group (P = 0.038), and dysphagia was significantly higher in the combined approach group (P = 0.001). LR (P > 0.999), OS (P = 0.655), and time to both outcomes (log-rank test, OS, P = 0.051, LR, P = 0.187) were not significantly different. Of the 51 patients alive at 3 months, only 19 (37.2%) obtained imaging ≥3 months. Fusion was seen in 11/19 (57.8%) at a median of 8.3 months (interquartile range, 4.6-13.7). Among the anterior corpectomies, the following graft/cage was used: 6 allografts (54.5%), 4 static cages (36.3%), and 1 expandable cage (9.0%), with no difference found in outcomes among the 3 groups.

CONCLUSIONS

The only discernible differences between operative approaches were that patients undergoing an anterior approach had higher rates of new postoperative neurologic deficit, and the combined approach group had higher rates of postoperative dysphagia.

Long-term outcomes in patients treated with tissue-sparing posterior cervical fusion to revise a 1-level pseudarthrosis following ACDF

STUDY DESIGN

Observational Study BACKGROUND: Symptomatic pseudarthrosis is one long-term complication in patients treated with anterior discectomy and fusion (ACDF). When revising a pseudarthrosis, a surgeon must decide to intervene posteriorly and/or anteriorly. Open posterior cervical fusion (PCF) is attractive for high rates of arthrodesis, however this technique introduces risks of added complications resulting from extensive soft tissue dissection. The purpose of this study was to assess long-term outcomes in patients undergoing tissue-sparing PCF with facet instrumentation to treat a single level pseudarthrosis.

METHODS

Forty-five subjects were recruited from six participating sites. All subjects had a history of ACDF that was subsequently revised with tissue-sparing PCF to treat symptomatic pseudarthrosis at one level. Long-term radiographic assessments included flexion and extension X-ray and multi-planar CT. Subjects additionally completed a patient satisfaction questionnaire. Radiographs were assessed by investigators and an independent core imaging lab to diagnose implant integrity and arthrodesis at the revised levels.

RESULTS

The revision procedure required a median 49 min to complete with an estimated blood loss of 10 cc. Subjects were discharged a median 1 day following treatment. There were no instances of hospital re-admission nor subsequent surgical interventions. Study follow-up assessments were performed a median 39 months from revision. Surgeons diagnosed complete fusion in 91 % of cases. The core imaging lab identified bridging bone across the revised segment in 80 % of cases. Range of motion was < 2° in 93 % of cases. Seventy-four percent of subjects reported being satisfied with their outcomes.

CONCLUSIONS

This study summarizes long-term radiographic outcomes in a cohort of patients receiving tissue-sparing PCF for the treatment of pseudarthrosis. Assessed years after revision, patients achieved rates of arthrodesis similar to open PCF without the soft tissue dissection responsible for perioperative morbidity and long-term soft tissue pain.

Longer Screws Decrease the Risk of Radiographic Pseudarthrosis Following Elective Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

In patients undergoing elective anterior cervical discectomy and fusion (ACDF), we sought to determine the impact of screw length on: (1) radiographic pseudarthrosis, (2) pseudarthrosis requiring reoperation, and (3) patient-reported outcome measures (PROMs).

METHODS

A single-institution, retrospective cohort study was undertaken from 2010-21. The primary independent variables were: screw length (mm), screw length divided by the anterior-posterior vertebral body diameter (VB%), and the presence of any screw with VB% < 75% vs all screws with VB% ≥ 75%. Multivariable logistic regression controlled for age, BMI, gender, smoking, American Society of Anesthesiology grade, number of levels fused, and whether a corpectomy was performed.

RESULTS

Of 406 patients undergoing ACDF, levels fused were: 1-level (39.4%), 2-level (42.9%), 3-level (16.7%), and 4-level (1.0%). Mean screw length was 14.3 ± 2.3 mm, and mean VB% was 74.4 ± 11.2. A total of 293 (72.1%) had at least one screw with VB% < 75%, 113 (27.8%) had all screws with VB% ≥ 75%, and 141 (34.7%) patients had radiographic pseudarthrosis at 1-year. Patients who had any screw with VB% < 75% had a higher rate of radiographic pseudarthrosis compared to those had all screws with VB% ≥ 75% (39.6% vs 22.1%, P < .001). Multivariable logistic regression revealed that a higher VB% (OR = .97, 95%CI = .95-.99, P = .035) and having all screws with VB% ≥ 75% (OR = .51, 95%CI = .27-.95, P = .037) significantly decreased the odds of pseudarthrosis at 1-year, with no difference in reoperation or PROMs (all P > .05).

CONCLUSION

Longer screws taking up ≥75% of the vertebral body protected against radiographic pseudarthrosis at 1-year. Maximizing screw length in ACDF is an easily modifiable factor directly under the surgeon's control that may mitigate the risk of pseudarthrosis.

Identification of Novel Genetic Markers for the Risk of Spinal Pathologies: A Genome-Wide Association Study of 2 Biobanks

BACKGROUND

Identifying genetic risk factors for spinal disorders may lead to knowledge regarding underlying molecular mechanisms and the development of new treatments.

METHODS

Cases of lumbar spondylolisthesis, spinal stenosis, degenerative disc disease, and pseudarthrosis after spinal fusion were identified from the UK Biobank. Controls were patients without the diagnosis. Whole-genome regressions were used to test for genetic variants potentially implicated in the occurrence of each phenotype. External validation was performed in FinnGen.

RESULTS

A total of 389,413 participants were identified from the UK Biobank. A locus on chromosome 2 spanning GFPT1, NFU1, AAK1, and LOC124906020 was implicated in lumbar spondylolisthesis. Two loci on chromosomes 2 and 12 spanning genes GFPT1, NFU1, and PDE3A were implicated in spinal stenosis. Three loci on chromosomes 6, 10, and 15 spanning genes CHST3, LOC102723493, and SMAD3 were implicated in degenerative disc disease. Finally, 2 novel loci on chromosomes 5 and 9, with the latter corresponding to the LOC105376270 gene, were implicated in pseudarthrosis. Some of these variants associated with spinal stenosis and degenerative disc disease were also replicated in FinnGen.

CONCLUSIONS

This study revealed nucleotide variations in select genetic loci that were potentially implicated in 4 different spinal pathologies, providing potential insights into the pathological mechanisms.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Anterior cervical discectomy and fusion, open-door laminoplasty, or laminectomy with fusion: Which is the better treatment for four-level cervical spondylotic myelopathy?

Four-level cervical spondylotic myelopathy (CSM) is a common disease affecting a large number of people, with the optimal surgical strategy remaining controversial. This study compared the clinical outcomes, radiological parameters, and postoperative complications of primarily performed surgical procedures such as anterior cervical discectomy and fusion (ACDF), open-door laminoplasty (LAMP), and laminectomy with fusion (LF) in treating four-level CSM. A total of 116 patients who received ACDF (38 cases), LAMP (45 cases), and LF (33 cases) were followed up for a minimum of 24 months were enrolled in this study and retrospectively analyzed. Clinical outcomes were evaluated using the Japanese Orthopedic Association (JOA) scoring system, the Neck Disability Index (NDI), and the Visual Analogue Scale (VAS). Changes in the curvature of the cervical spine were determined using the cervical curvature index (CCI) and the C2-C7 Cobb angle. Cervical mobility was evaluated using the C2-C7 range of motion (ROM) and active cervical ROM (aROM). Complications were recorded and compared among the three groups. All patients achieved significant improvement in JOA, NDI, and VAS scores at the final follow-up (P < 0.05), whereas no remarkable difference was found among the groups (P > 0.05). In addition, both C2-7 ROM and aROM were significantly reduced in the three groups and LAMP showed the least reduction relatively. As for complications, LAMP showed the lowest overall incidence of postoperative complications, and patients in the ACDF group were more susceptible to dysphagia, pseudoarthrosis than LAMP and LF. Considering improvements in clinical symptoms and neurological function, no remarkable difference was found among the groups. Nevertheless, LAMP had advantages over the other two surgical procedures in terms of preserving cervical mobility and reducing postoperative complications.

Incidence of Pseudarthrosis and Subsequent Surgery After Cervical Fusion Surgery: A Retrospective Review of a National Health Care Claims Database

BACKGROUND

Cervical pseudarthrosis is a postoperative adverse event that occurs when a surgically induced fusion fails to establish bone growth connecting the 2 regions. It has both clinical and financial implications and may result in significant patient morbidity; it continues to be one of the leading causes of pain after surgery.

METHODS

A retrospective longitudinal cohort study was performed. Patients in the IBM MarketScan Commercial Claims and Encounters (CCAE) database, 18-64 years old, who underwent elective cervical fusions during 2015-2019 were included. Patients with trauma, infection, or neoplasm were excluded. Patients were followed for 2 years from surgical fusion for occurrence of pseudarthrosis. After pseudarthrosis, subsequent surgery was documented, and cumulative incidence curves, adjusted for patient/procedure characteristics, with 95% confidence intervals (CIs) were generated. Risk factors were evaluated with multivariable Cox regression analysis.

RESULTS

The cohort included 45,584 patients. The 1-year and 2-year incidence of pseudarthrosis was 2.0% (95% CI, 1.9%-2.2%) and 3.3% (95% CI, 3.1%-3.5%), respectively. Factors significantly associated with increased risk of pseudarthrosis were female gender, current/previous substance abuse, previous spinal pain in the cervical/thoracic/lumbar spine, and Elixhauser score ≥5. Factors significantly associated with decreased risk of pseudarthrosis were anterior cervical approach, use of an interbody cage, and 2-level or 3-level anterior instrumentation. The 1-year and 2-year incidence of subsequent surgery in patients with pseudarthrosis was 11.7% (95% CI, 9.6%-13.7%) and 13.8% (95% CI, 11.5%-16.2%), respectively.

CONCLUSIONS

Cervical pseudarthrosis and subsequent surgery still occur at a low rate. Surgical factors such as anterior approach, interbody cage use, and anterior instrumentation may reduce pseudarthrosis risk.