Technical Repeatability and Reproducibility of the Stress Radiographs Performed with the Vezzoni-Modified Badertscher Hip Distension Device

Abstract

Objective The aim of this study was to evaluate the repeatability and reproducibility of the radiographical stress technique using the Vezzoni-modified Badertscher distension device (VMBDD). Materials and Methods Stress radiographs of 10 dogs obtained with the VMBDD were performed consecutively by two different operators and then measured twice by a third veterinarian. The technical repeatability was first assessed individually for the two operators who took the stress radiographs, followed by the technical reproducibility. The obtained variances were used to calculate the 95% limits of agreement for the measurement repeatability, the technical repeatability and the technical reproducibility. Results Both the technical repeatability and reproducibility of the VMBDD technique were good, with the 95% limits of agreement of the measurement repeatability and technical repeatability equalling ± 0.07 overall, and the 95% limits of agreement of the technical reproducibility being ± 0.09. Clinical Significance These results, in combination with the previous results for the measurement of the laxity index, support the use of the VMBDD as a reliable in-house evaluation method to assess the hip joint by trained clinicians. For screening purposes, however, we suggest to limit the number of evaluators, to limit the variability.

Quantifying the Stress in Stress Radiographs to Determine Sufficient Laxity of the Coxofemoral Joint: A Canine Hip Dysplasia Cadaveric Study

“…Furthermore, the coefficients, which are depicting the observed differences in LI max directly, of all these variables were also very small, and at most equal to the reference repeatability values reported when measuring the LI. 9 This also substantiates the finding that they are not significant not only statistically but also clinically. Either way, their effect would have been too small to be relevant.…”

“…This substantiates the clinical observation that the VMBDD was a method with a good technical repeatability and reproducibility to evaluate the hip joints when used by trained clinicians. 9 It might be considered a limitation of this study that all radiographs and measurements were performed by the same examiner. The benefit of choosing an experienced person is that the signal-to-noise ratio remains high.…”

“…However, a 9% LI standard deviation does correspond with similar values as the ones reported earlier (and deemed to be sufficiently good) at the LI max . 9 Our third goal was to measure and calculate the force necessary to cause adequate subluxation of the hip joint. The force at which 90% of the hips reach at least 90% of their LI max was 95.32 N. This corresponds to a force of 9.7 kg, which is expected to be feasible for every person performing the procedure, especially because the VMBDmD functions as a lever and thus the force exerted by the examiner can be lower.…”

“…After each radiograph, the quality was assessed, based on the criteria described by Bertal and colleagues. 9 If the quality was considered inferior, a retake was performed at a comparable force.…”

“…However, the technical repeatability and reproducibility of the VMBDD is good when performed by trained clinicians. 9 For the VMBDD, the measurement of laxity is called the laxity index (LI), while for PennHIP, it is termed the distraction index . The LI correlates well with the Fédération Cynologique Internationale (FCI) score on a standard ventrodorsal (SVD) projection, but in FCI-normal dogs a wide range of passive hip joint laxity persists.…”