Intra- and interrater reliabilities and a method comparison of 2D and 3D techniques in cadavers to determine sacroiliac screw loosening

Abstract

Sacroiliac (SI) screw loosening may indicate persistent instability, non-union and contribute to pain. Yet, there is no reliable objective measurement technique to detect and monitor SI screw loosening. In 9 cadaveric pelvises one of two SI screw was turned back approximately 20 mm and subsequently assessed by optical measurement, fluoroscopy and a 3D scan using an image intensifier. CTs were segmented and a contour-based registration of the 3D models and the fluoroscopies was performed to measure SI backing out (X-ray module). Three independent observers performed measurements with three repetitions. Deviation of the measurement techniques to the 3D scan, intra- and interrater reliabilities and method equivalence to the 3D scan were assessed. The X-ray module and two fluoroscopic measurement techniques yielded a difference less than 5 mm compared to the 3D scan and equivalence to the 3D scan. Intrarater reliability was for two observers and almost all techniques very good. Three fluoroscopic measurement techniques and optical measurements displayed a very good interrater reliability. The 3D scan and X-ray module yielded the most precise values for SI screw loosening but only the fluoroscopic measurement of the inlet lateral loosening displayed a good reliability and equivalence to the 3D scan.

New method to apply the lumbar lordosis of standing radiographs to supine CT-based virtual 3D lumbar spine models

“…The method leverages the capabilities of the commercially available X-ray module of Materialise Mimics® software for the rigid registration of lumbar vertebral 3D geometries to biplanar standing radiographs. In their 2019 paper 31 , Pieroh et al successfully used the same software package for the evaluation of sacroiliac screw loosening as well as several others in different orthopedic use cases [32][33][34][35] .…”

Incidence of and Risk Factors for Screw Loosening after Iliosacral Screw Fixation for Posterior Pelvic Ring Injury

“…The standards were graded as poor (>21 mm), general (11–20 mm), good (5–10 mm), and excellent (<5 mm). Screw loosening was assessed by radiography and confirmed by CT. 9 Fluoroscopy (anteroposterior, inlet, and outlet radiographs) was examined 2 days after operation and at every follow‐up visit. All the information was collected by experienced and trained doctors.…”

“…Failure occurs when screw loosening affects the stability of the pelvic ring, and leads to loss of fracture reduction, requiring further treatment. 8,9 Several factors have been identified as the risk factors for screw loosening in previous studies, with an incidence rate ranging from 2% to 20%. 7,8,[10][11][12][13] According to Georg et al, 12 percutaneous iliosacral screws placed in the first sacral segment (S1) and second sacral segment (S2) had a low risk of screw loosening.…”

“…A simple backout means that the screw is slightly detached and does not cause pain or loss of fracture reduction, especially if the screw loosening persists without progress. Failure occurs when screw loosening affects the stability of the pelvic ring, and leads to loss of fracture reduction, requiring further treatment 8,9 …”

“…Failure occurs when screw loosening affects the stability of the pelvic ring, and leads to loss of fracture reduction, requiring further treatment. 8 , 9 …”