Abstract
BackgroundA small, but unstable, saw-gap may hinder bone-bridging and induce development of painful sternal dehiscence. We propose the use of Radiostereometric Analysis (RSA) for evaluation of sternal instability and present a method validation.MethodsFour bone analogs (phantoms) were sternotomized and tantalum beads were inserted in each half. The models were reunited with wire cerclage and placed in a radiolucent separation device. Stereoradiographs (n = 48) of the phantoms in 3 positions were recorded at 4 imposed separation points. The accuracy and precision was compared statistically and presented as translations along the 3 orthogonal axes. 7 sternotomized patients were evaluated for clinical RSA precision by double-examination stereoradiographs (n = 28).ResultsIn the phantom study, we found no systematic error (p > 0.3) between the three phantom positions, and precision for evaluation of sternal separation was 0.02 mm. Phantom accuracy was mean 0.13 mm (SD 0.25).In the clinical study, we found a detection limit of 0.42 mm for sternal separation and of 2 mm for anterior-posterior dislocation of the sternal halves for the individual patient.ConclusionRSA is a precise and low-dose image modality feasible for clinical evaluation of sternal stability in research.Trial registrationClinicalTrials.gov Identifier: NCT02738437, retrospectively registered.
Highlights
A small, but unstable, saw-gap may hinder bone-bridging and induce development of painful sternal dehiscence
The clinical diagnosis of sternal instability is determined by manual palpation by a physician and the radiological diagnosis may be confirmed by Computed Tomography (CT)
We propose the use of a radiostereometric analysis (RSA), which is a low-dose image diagnostic modality, to diagnose sternal instability in clinical studies following cardiac surgery)
Summary
A small, but unstable, saw-gap may hinder bone-bridging and induce development of painful sternal dehiscence. The procedure is quick and efficient, and has only two major complications: sternal infection (1–3% of patients) and non-union (2–8% of patients). Sternal non-union is usually a result of primary dehiscence, poor wound healing, or premature overexertion [1]. 56% [2] experience chronic postoperative pain, which might be an indicator of underdiagnosed sternal non-unions. The clinical diagnosis of sternal instability is determined by manual palpation by a physician and the radiological diagnosis may be confirmed by Computed Tomography (CT). Both methods are correlated with a high degree of intra- and inter-observatory variance. We have previously shown the relative intra-observer variance of radiological evaluation of sternal CT to be a mean − 9.32% (SD ± 16.18), and the relative inter-observer variance to be mean − 14.29% (SD ± 14.88) [3]
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