Correlation of Arthrodesis Stability with Degree of Joint Fusion on MDCT

Abstract

After arthrodesis of the ankle or subtalar joint, MDCT scans can be used to determine whether that joint is likely to be stable if > 33% of the joint has visible bone fusion on sagittal MDCT images.

Computer Tomography assessment of the fusion rate after posterior arthroscopic subtalar arthrodesis

“…The authors arbitrarily defined a CT finding of nonunion as 0-33% fusion on CT, partial union as 34-66% fusion, and complete union as 67-100% fusion. Dorsey et al, in a recent CT study, confirmed that a 33% CT fusion ratio threshold could accurately discriminate between clinical stability and instability [6]. Our study confirms these findings, as we found a globally low rate of bone fusion at between 33% and 50% in the majority of clinically stable patients.…”

“…The finding of persistent radiolucency crossing the entire joint space at six months combined with loosening, bending, or breakage of fixation screws are still a highly specific sign of arthrodesis nonunion but these signs are rarely present and were never found in our non-union cases. Moreover, we believe as does Dorsey [6] that a small number of asymptomatic patients can have a low percentage of bone fusion after attempted arthrodesis. We report the first study in which the results of an arthroscopic subtalar posterior arthrodesis have been studied with a CT-scan rather than plain radiography.…”

“…2). The sum of the lengths of the fused segments on all slices was then divided by the sum of the lengths of the joint surfaces to calculate the fusion ratio according to the technique described by Dorsey et al [6].…”

A Prospective Pilot Study of B2A-Coated Ceramic Granules (Amplex) Compared to Autograft for Ankle and Hindfoot Arthrodesis

“…Similar techniques have been used by other investigators in foot and ankle arthrodesis studies. 9,11,17,28 When compared to autograft, the B2A-granule group had a trend for a higher radiographic fusion rate (100% vs 92%) at 6-month follow-up as defined by evidence of bridging bone over at least 50% of the joint. The fusion rates for B2A-granules in the current study were higher than those observed in the pilot study of Daniels et al 7 using rhPDGF-BB, which showed a fusion rate of 75% (44/59) at 36 weeks.…”

Reproducibility of Computed Tomography to Evaluate Ankle and Hindfoot Fusions

“…This notion has spurred the increasing use of computed tomography (CT) evaluation for arthrodesis in the orthopaedic community. 1,3,10 In a recent study evaluating 15 patients who had undergone hindfoot fusion, it was found that CT scan was a better modality for evaluating the extent of fusion in the hindfoot. Specifically, the CT scan could delineate the area of trabecular bridging at a given arthrodesis site more clearly.…”