SLR - May 2023 - Michael Radcliffe, DPM
Title: How to assess consolidation after foot and ankle arthrodesis with computed tomography. A systematic reviewReference: Willems A, Houkes CM, Bierma-Zeinstra SMA, Meuffels DE. How to assess consolidation after foot and ankle arthrodesis with computed tomography. A systematic review. Eur J Radiol. 2022 Sep 5;156:110511. doi: 10.1016/j.ejrad.2022.110511. PMID: 36108477.
Level of Evidence: III
Scientific Literature Review
Reviewed By: Michael Radcliffe, DPM
Residency Program: UF College of Medicine - Jacksonville; Jacksonville, FL
Podiatric Relevance: Joint arthrodesis in the foot and ankle is a commonly performed procedure. However, nonunion remains a detrimental complication that can occur. Computed tomography (CT) scans are considered the best imaging modality to comprehensively assess bone consolidation. Foot and ankle surgeons must understand how to best interpret the results of CT scans and implement those results into patient care. The authors aimed to investigate how consolidation after foot and ankle arthrodesis procedures is interpreted and reported in CT scans, evaluate reliability and validity of those methods, and provide a recommendation on the ideal methodology to use.
Methods: A systematic review was performed to find studies that used CT scans to assess consolidation in patients undergoing foot or ankle arthrodesis. Two independent reviewers selected eligible studies and ultimately included 34 studies. Primary outcomes collected included if consolidation was the primary outcome, study type, aim of the studies, CT settings, number of patients, and patient population. Secondary outcomes recorded were methods of consolidation assessment, who assessed consolidation, how many assessors participated, if assessors were blinded, reliability measures, validity measures, and if a study referred to methodologies of other studies. The COSMIN tool was used to assess risk of bias assessment.
Results: High risk of bias was found in 27 out of 34 studies (80%) due to lack of reporting reliability measurements and not describing or citing an adequate method for consolidation assessment. Thirty studies assessed consolidation with CT as the primary outcome. The studies included 27 retro- or prospective cohorts and 7 randomized controlled trials. Primary aims of the studies varied and included effect of bone healing stimulating therapies, types of osteosynthesis material or operative techniques, correlating fusion ratio to clinical outcomes, and interrater reliability of consolidation assessment from CT. Consolidation assessment methods utilized were subjective categorization into groups and fusion ratio calculation followed by application of a fusion threshold. Fusion ratio was defined as sum of widths of fused segments of joints divided by the sum of widths of joint surfaces. Reliability scores showed that intrarater and interrater reliability was excellent when fusion ratios and fusion thresholds were applied. Validity measures found that a fusion ratio around 30-33% correlated to clinically stable arthrodesis sites.
Conclusions: The authors recommend that when assessing consolidation arthrodesis sites, the fusion ratio should be calculated and a fusion threshold value of 33% be used to discriminate between non-fused and fused joints. This objective method to assessing consolidation of fusion sites produces high interrater reliability. Continued optimization of an accurate fusion threshold value for CT assessment of fusion sites based on clinical correlation will enhance the ability to use CT in postoperative monitoring. Limitations of this study include potential exclusion of studies based on search methods and limited information on who performed consolidation assessment and assessors’ experience. These findings offer a reliable method to assess fusion on CT and evidence that 33% fusion correlates with clinical stability. This provides reassurance to both surgeon and patient that even with a seemingly low fusion ratio, the fusion result can still be stable.