CT-based micromotion analysis for tracking fracture displacement and fragment movement in trochanteric hip fractures: an agreement study
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
Background and purpose 2-dimensional radiographs may underestimate 3-dimensional fracture displacement. CT-based micromotion analysis (CTMA) enables precise quantification of interfragmentary movement in 3 dimensions. We aimed to evaluate CTMA for quantifying fracture displacement, surgical reduction, and postoperative fragment movement in trochanteric hip fractures, and assessed measurement agreement from repeated follow-up scans. s1 Methods We conducted a prospective cohort study including 15 patients with trochanteric fractures treated with a cephalomedullary nail at Uppsala University Hospital between 2020 and 2023. Each patient underwent CT imaging preoperatively, postoperatively, and at follow-up. Measurement agreement was assessed using 2 follow-up CT scans acquired after patient repositioning, when the fractures were healed. The femoral shaft (or nail) served as the fixed reference, and the femoral head (or spiral blade) was analyzed relative to the mirrored contralateral hip to quantify fracture displacement. Fracture movement during healing was assessed by comparing postoperative and follow-up scans. s2 Results 12 patients had complete imaging. Measurement agreement between repeated CTMA scans showed sub-millimetric repeatability for translation and < 1° for rotation. Mean initial fracture displacement relative to the mirrored contralateral hip was 55.6° in total rotation and 48.4 mm in total translation, improving postoperatively to 17.5° and 15.9 mm, and remaining
Abstract
Background and purpose 2-dimensional radiographs may underestimate 3-dimensional fracture displacement. CT-based micromotion analysis (CTMA) enables precise quantification of interfragmentary movement in 3 dimensions. We aimed to evaluate CTMA for quantifying fracture displacement, surgical reduction, and postoperative fragment movement in trochanteric hip fractures, and assessed measurement agreement from repeated follow-up scans. s1 Methods We conducted a prospective cohort study including 15 patients with trochanteric fractures treated with a cephalomedullary nail at Uppsala University Hospital between 2020 and 2023. Each patient underwent CT imaging preoperatively, postoperatively, and at follow-up. Measurement agreement was assessed using 2 follow-up CT scans acquired after patient repositioning, when the fractures were healed. The femoral shaft (or nail) served as the fixed reference, and the femoral head (or spiral blade) was analyzed relative to the mirrored contralateral hip to quantify fracture displacement. Fracture movement during healing was assessed by comparing postoperative and follow-up scans. s2 Results 12 patients had complete imaging. Measurement agreement between repeated CTMA scans showed sub-millimetric repeatability for translation and < 1° for rotation. Mean initial fracture displacement relative to the mirrored contralateral hip was 55.6° in total rotation and 48.4 mm in total translation, improving postoperatively to 17.5° and 15.9 mm, and remaining essentially stable at follow-up. Between the postoperative and follow-up scans, total movement of the femoral head averaged 5.4° (95% confidence interval [CI] 2.8–8.1) and 6.4 mm (CI 3.9–8.9). Spiral blade total translation averaged 5.4 mm (CI 3.0–7.9). Observed movement followed expected directions, with predominant femoral shortening (z-translation −4.4 mm), medialization (x-translation −3.3 mm), and slight external rotation (z-rotation +2.4°) of the femoral shaft. s3 Conclusion CTMA demonstrated good measurement agreement and repeatability for quantifying fracture displacement, surgical reduction, and postoperative fragment movement in trochanteric fractures. s4