Michiel Herteleer

Purpose: Evaluation of ultra-high resolution (UHR) and spectral photon-counting CT (PCCT) for pelvic trabecular bone (ptBone) detection and volumetric bone mineral density (vBMD) measurement using micro-CT (µCT) as reference standard and energy-integrating detector CT (EID-CT) as clinical benchmark.Methods: Four human cadavers underwent in-situ pelvic PCCT and EID-CT imaging. Thirteen specimens consisting of the sacral and fifth lumbar vertebrae were subsequently extracted and scanned with µCT. Spectral PCCT was evaluated using X-ray attenuation decomposition (XAD), calculated from virtual monoenergetic images (VMIs). ptBone detection was assessed using classification metrics consisting of sensitivity, specificity, and Dice, and contrast-to-noise ratio (CNR). vBMD was quantified on ex-vivo sacral PCCT scans with and without calibration phantom using respectively poly-energetic images and XAD. Secondary analyses evaluated the effect of radiation dose and PCCT reconstruction parameters.Results: UHR PCCT achieved the highest trabecular detection accuracy, although overall agreement with µCT remained modest (Dice coefficient of 0.35±0.03 vs 0.23-0.27±0.02 for spectral PCCT and 0.24±0.02 for EID-CT, p<0.05). Increasing radiation dose improved CNR but reduced classification metrics. Softer reconstruction kernels and larger matrix sizes yielded the best performance. High resolution PCCT (HR) showed a stronger Pearson’s correlation with vBMD derived from µCT (Pearson’s r=0.87) than UHR PCCT, spectral PCCT and EID-CT (Pearson’s r=0.46-0.62).Conclusion: UHR PCCT improved ptBone detection compared to spectral PCCT and EID-CT, although agreement with µCT remained low to moderate. HR PCCT-based vBMD correlated highly to µCT-based vBMD, supporting its potential for opportunistic osteoporosis assessment on routine pelvic PCCT imaging.

The percutaneous placement of iliosacral (IS) and transsacral (TS) screws has become a standard practice for the treatment of pelvic fractures. Due to the complex sacral anatomy, accurate screw placement is essential to avoid complications, such as neurovascular injury. The goal of this study was to quantify the deviation between planned and executed screw trajectories and to identify associated factors. We conducted a retrospective cohort study on treating 51 patients with pelvic fractures from August 2021 to December 2023, using a total of 95 IS and TS screws. Preoperative planning was performed to generate a volume-rendered reconstruction that replicates standard intraoperative fluoroscopic views (lateral, inlet, outlet). These simulated images served as references during surgery. Postoperative Computed Tomography (CT) data were integrated with the preoperative plan to quantify screw deviations through accuracy metrics. Median deviation from the planned entry point was 8.8 mm (6.2-12.8) for IS and 6.2 mm (4.2-9.0) for TS. Average distances were 5.7 mm (3.5-8.0) for IS and 4.8 mm ± 2.0 for TS. Angle deviation was 8.2° (4.6-12.8) for IS and 3.9° ± 1.8 for TS. One patient experienced loss of sensibility due to an IS screw conflicting with the L5 nerve root, needing revision surgery. A positive association was observed between BMI and the distance between entry points for TS screws. Learning curve analysis showed no significant change in accuracy over time. Preoperative navigation using volume-rendered virtual imaging could not guarantee a precise positioning of IS and TS screws. Although geometric deviations were observed between planned and placed screws, clinical outcomes were favourable, with a very low complication rate. The technique proved feasible and safe in clinical practice, achieving moderate overall accuracy, and may therefore be particularly valuable for less-experienced surgeons.

Introduction: Timely surgery within the next calendar day (<48h) is recommended for proximal femoral fractures (PFF) according to NICE guidelines. In contrast, no standardized fast-track protocols exist for periprosthetic hip fractures (PHF), potentially causing surgical delays. We aimed to compare the time to surgery in PHF and PFF patients, the causes of surgical delay, as well as complications and mortality rate.Materials and Methods: We retrospectively analyzed PHF patients treated surgically at a university level one trauma center. Time to surgery, reasons for delay, complication rates, and mortality were assessed. Subgroup analyses were performed by surgical timing (early vs. delayed) and age (≥75 years old). A previously published PFF cohort served as control group.Results: Median time to surgery was significantly longer in PHF patients compared to PFF patients (resp. 43.6 hours (IQR 21.1-85.7) vs 16.8 hours (IQR 9.7-23.1)). Early surgery (within the next calendar day) occurred in 43.8% of PHF versus 91.2% of PFF patients. Delays in PHF were mainly due to surgeon availability (63.1%) and/or logistical factors (60.6%), whereas in PFF delay was predominantly patient-related (anticoagulation, comorbidities, delayed referral). Complication rates in PHF patients were similar for early and delayed surgery. Kaplan–Meier analysis revealed a significantly lower survival in patients with PFF (log-rank χ²=23.301; p<0.001) and no difference in mortality between early and delayed surgery in the PHF group (log-rank χ² = 2.353; p = 0.125). Age adjustment (≥75 years old) for PHF patients showed similar trends.Conclusion: PHF patients experienced significantly longer surgical delays than PFF patients, predominantly due to logistical and organizational factors. In PHF, delayed surgery was not associated with increased complication rates or differences in overall survival. Despite longer surgical delays, PHF patients demonstrated lower mortality compared with PFF patients beyond 30 days. These findings suggest that, in selected PHF cases, postponing surgery until appropriate expertise and resources are available may be justified.

A 73-year-old patient with a complex sacral fracture underwent stabilising orthopaedic surgery. Postoperative brain CT showed fat droplets in the subarachnoid space and lateral ventricle. These fat droplets migrated into the cerebrospinal fluid by a tear in the sacral thecal sac. Teaching point: Intracranial subarachnoid fat droplets may be observed after spinal surgery.

Summary This study aimed to describe the incidence of hospitalizations for osteoporotic fractures in patients aged 50 years and over in Belgium between 2010 and 2021. A declining trend in crude and age-adjusted hospitalization incidence was observed, however, the absolute number of hospitalisations for osteoporotic fractures increased due to demographic changes. Purpose The secular trends of hospitalizations for hip and other osteoporotic fractures between 2010 and 2021 in patients aged 50 years and over in Belgium are unknown. This study aimed to describe the incidence of hospitalizations for osteoporotic fractures in patients aged 50 years and over in Belgium between 2010 and 2021. Methods Population-based, retrospective study based on hospitalization data extracted by the national database NIHDI and demographical data retrieved from the Belgian Federal Bureau for Statistics. Data were combined to determine the crude and age-standardized hospitalization incidence of fractures of the hip, distal femur, pelvis, humerus, wrist, and spine (2010 as the reference year). Results A total of 445,234 hospitalizations for osteoporotic fractures were reported between 2010 and 2021 (excluding 2015). Hospitalizations increased by 5.8% between 2010 and 2021 (p = 0.013) with a higher increase in men (12.1%; p = 0.001) compared to women (4.1%; p = 0.041). The crude incidence of hospitalizations for all fractures per 100,000 persons per year decreased from 990 to 910 between 2010 and 2021 (p = 0.572). The age-standardized incidence for hospitalizations of any osteoporotic fracture in men declined from 5.30/1,000 to 4.42/1,000 (p = 0.010). In women, a similar decrease was observed (13.84/1,000 to 11.62/1,000; p = 0.003). Both age-standardized hospitalizations for hip and non-hip fractures showed a decrease in both sexes. Conclusion Although a declining trend in the crude incidence per 100,000 and in the age-adjusted incidence of hospitalizations for osteoporotic fractures was observed, the absolute number of hospitalizations for osteoporotic fractures increased due to the demographic change of an ageing population.

Introduction The incidence of osteoporotic pelvic fractures is increasing. The broken anterior pelvic ring is preferentially fixed with long intramedullary screws, which require a good understanding of the patient-specific anatomy to prevent joint perforation. The aim of this study was to assess the variability of the superior pubic ramus and the supra acetabular corridors’ length and width using statistical shape modelling. Materials and methods A male and female statistical shape model was made based on 59 forensic CT scans. For the superior pubic ramus and the supra acetabular corridor the longest and widest completely fitting cylinder was created for the first 5 principal components (PC) of both models, male and female pelvises separately. Results A total of 59 pelvises were included in this study of which 36 male and 23 female. The first 5 principal components explained 75% and 79% of the pelvic variation in males and females, respectively. Within 3 PCs of the female statistical shape model (SSM) a superior pubic ramus corridor of < 7.3 mm was found, 5.5 mm being the narrowest linear corridor measured. Both corridors in all PCs of the male SSM measured > 7.3 mm. Conclusion Within females a 7.3 mm and 6.5 mm screw won’t always fit in the superior pubic ramus corridor, especially if a flat sacrum, a small pelvis or a wide subpubic angle are present. The supra acetabular corridor did not seem to have sex-specific differences. In the supra-acetabular corridor there was always enough space to accommodate a 7.3 mm screw, both in males and females.