Pseudarthrosis in Spine Surgery: Diagnosis and Treatment

Radiologic Assessment of Interbody Fusion: A Systematic Review on the Use, Reliability, and Accuracy of Current Fusion Criteria

BACKGROUND

Lumbar interbody fusion (IF) is a common procedure to fuse the anterior spine. However, a lack of consensus on image-based fusion assessment limits the validity and comparison of IF studies. This systematic review aims to (1) report on IF assessment strategies and definitions and (2) summarize available literature on the diagnostic reliability and accuracy of these assessments.

METHODS

Two searches were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Search 1 identified studies on adult lumbar IF that provided a detailed description of image-based fusion assessment. Search 2 analyzed studies on the reliability of specific fusion criteria/classifications and the accuracy assessed with surgical exploration.

RESULTS

A total of 442 studies were included for search 1 and 8 studies for search 2. Fusion assessment throughout the literature was highly variable. Eighteen definitions and more than 250 unique fusion assessment methods were identified. The criteria that showed most consistent use were continuity of bony bridging, radiolucency around the cage, and angular motion <5°. However, reliability and accuracy studies were scarce.

CONCLUSION

This review highlights the challenges in reaching consensus on IF assessment. The variability in IF assessment is very high, which limits the translatability of studies. Accuracy studies are needed to guide innovations of assessment. Future IF assessment strategies should focus on the standardization of computed tomography-based continuity of bony bridging. Knowledge from preclinical and imaging studies can add valuable information to this ongoing discussion.

LEVEL OF EVIDENCE

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

The Approach to Pseudarthrosis After Adult Spinal Deformity Surgery: Is a Multiple-Rod Construct Necessary?

STUDY DESIGN

Retrospective study.

OBJECTIVES

Our goal was to evaluate the rate of rod fracture and persistent pseudarthrosis in cohorts of patients treated with a dual rod or multiple-rod construct in revision surgery for pseudarthrosis.

METHODS

A dual rod construct was used in 23 patients, and a multiple rod construct in 24 patients, spanning the pseudarthrosis level. Two-year fusion grading, and rates of pseudarthrosis and implant failure, were assessed.

RESULTS

There were no differences in patient or surgical characteristics between the groups: (2- rod construct: Age 60 ± 14, Levels 10 ± 5, 3-column osteotomy:17%; multiple-rod construct: Age: 62 ± 11, Levels 9 ± 4, 3-column osteotomy:30%). Patients in the multiple rod construct were transfused a greater volume of packed red blood cells (pRBCs) intraoperatively (2.6 ± 2.9 vs. 1.1 ± 1.5 U, p < 0.0001). At 2 year follow up there was no difference in fusion grades at the previous level of pseudarthrosis, the rate of rod fracture or pseudarthrosis between the 2 groups, or rate of reoperation for pseudarthrosis, rod fracture, wound infection, hardware prominence, or PJK/PJF.

CONCLUSIONS

Our data demonstrate no difference in fusion grade, or rates of rod fracture and revision at 2 years, after utilizing a dual rod versus multiple rod construct in revision surgery for pseudarthrosis. The low complication rates seen with either configuration warrant further investigation of the optimal instrumentation configuration.

Successful fusion versus pseudarthrosis after spinal instrumentation: a comprehensive imaging review

PURPOSE

Following spinal instrumentation and fusion, differentiating between successful arthrodesis and pseudoarthrosis on imaging can be challenging. Interpretation of such examinations requires understanding both the expected evolution of postoperative findings and the subtle indicators of pseudoarthrosis across multiple imaging modalities. Due to this level of intricacy, many clinicians lack familiarity with the subject beyond the more rudimentary concepts.

METHODS

This review provides an in-depth overview of the imaging of the post-operative spine, with particular emphasis on differentiating between pseudoarthrosis and arthrodesis.

RESULTS

A comprehensive overview of imaging of the post-operative spine is given, including the most common imaging modalities utilized, the expected post-operative findings, imaging findings in pseudoarthrosis, and imaging definitions of fusion.

CONCLUSION

Differentiating between pseudoarthrosis and arthrodesis in the postoperative spine is complex, and requires a robust understanding of various findings across many different modalities.

Failures in Thoracic Spinal Fusions and Their Management

Instrumented fixation and fusion of the thoracic spine present distinct challenges and complications including pseudarthrosis and junctional kyphosis. When complications arise, morbidity to the patient can be significant, involving neurologic injury, failure of instrumentation constructs, as well as iatrogenic spinal deformity. Causes of fusion failure are multifactorial, and incompletely understood. Most likely, a diverse set of biomechanical and biologic factors are at the heart of failures. Revision surgery for thoracic fusion failures is complex and often requires revision or extension of instrumentation, and frequently necessitates complex soft tissue manipulation to manage index level injury or to augment the changes of fusion.