Background and Objectives: Percutaneous iliosacral screw fixation is a standard treatment for posterior pelvic ring instability and sacral insufficiency fractures. However, conventional transsacral S1 screw fixation is associated with notable complication rates, most commonly implant loosening; dysmorphic sacral anatomy increases the risk of iatrogenic L5 or S1 nerve root injury. This study presents a modified S1 trajectory to engage the high-density bone of the anterior and cranial S1 vertebral body (promontory) by transferring preoperative 3D planning to intraoperative 2D fluoroscopy. Materials and Methods: This retrospective study analyzed implant placements for posterior pelvic ring instability, including high-velocity trauma and fragility fractures of the pelvis (FFPs). Preoperative computed tomography (CT) multiplanar reconstruction defined a modified corridor from a posterior-caudal iliac entry point directed cranially and ventrally into the S1 promontory. The 3D trajectory was transferred intraoperatively using standard 2D fluoroscopy (lateral, anteroposterior, inlet, and outlet views) with the patient prone. In cases of reduced bone quality or intended sacroiliac fusion, 3D-printed titanium implants (triangular or cylindrical threaded, 10.0-13.5 mm outer diameter) were selected over 7.5 mm cannulated screws. Results: Overall, 137 implants were placed in 71 patients: 13 cannulated screws in high-velocity pelvic ring trauma, 72 triangular titanium sacroiliac fusion implants (iFuse Implant System[®], SI-Bone), and 52 threaded titanium fusion implants (iFuse TORQ[®], SI-Bone) in patients with FFP. The modified trajectory consistently engaged the anterior and cranial S1 vertebral body. Postoperative 3D CT confirmed accurate placement of all implants. No iatrogenic nerve injuries or revisions for implant malposition occurred. Mean follow-up was 12 ± 9 months. Conclusions: Preoperative 3D CT planning combined with standard 2D fluoroscopy guided a modified S1 trajectory toward the cranial S1 vertebral body. Accurate and safe implant placement was achieved in the prone position without navigation systems, providing a practical alternative when standard transverse trajectories are limited by narrow bony corridors or sacral or pelvic dysmorphy.

Stress radiographs are widely used to define instability in lateral-compression type I injuries, but its applicability to fragility fractures of the pelvis (FFP) is unclear. We investigated whether lateral stress radiographs (LSRs) predict failure of non-operative treatment in patients with FFP types I and II. In this prospective observational study, 55 ambulatory patients aged ≥ 60 years with pubic ramus fractures underwent anteroposterior (AP) and inlet LSRs. Displacement was measured on AP LSRs using the femoral head (DFH) and teardrop (DTD), and cortical apposition at the superior pubic ramus fracture was assessed on inlet LSRs. Failure of non-operative treatment was defined as inability to ambulate due to persistent or worsening pain at any time during the first week after injury. Receiver operating characteristic analysis evaluated the predictive performance of LSR-derived parameters. Of the 55 patients, seven were classified as FFP type I and 48 as type II. Non-operative treatment failed in 21 patients (38.2%), all with type II fractures. Failure was associated with DFH ≥10 mm, DTD ≥10 mm, and a non-appositional displacement pattern on LSRs (all p < 0.001). The displacement pattern on inlet LSRs provided the highest predictive accuracy (area under the curve [AUC] 0.96), followed by DFH ≥10 mm (AUC 0.81) and DTD ≥ 10 mm (AUC 0.76). LSRs may help identify instability and predict failure of non-operative treatment in patients with FFP, particularly in those with FFP type II. Assessment of the displacement pattern on inlet LSRs-specifically the presence or absence of cortical apposition under stress-showed the greatest predictive value and may serve as a practical and intuitive indicator to guide early treatment decisions.

Advanced maternal age pregnancies are associated with a higher rate of cesarean sections (c-sections). As surgical procedures, c-sections increase the risk of maternal morbidity and mortality. Some have suggested that the increase in c-sections with maternal age reflects an age-related increase in feto-pelvic inadequacy. Here we evaluated whether maternal pelvic remodeling with respect to age and parity explains the increase in c-sections with age. We examined CT scans of recently deceased American individuals from the New Mexico Decedent Image Database (N = 299). The sample was subdivided for sex (male, female), age (15-34 years, 35-50 years, ≥51 years), and parity (parous, nulliparous). We took four obstetrically relevant measurements: anteroposterior (AP) inlet, AP outlet, mediolateral (ML) inlet, and ML midplane. Statistical analyses included the Welch Test to compare the age groups and the Wilcoxon-Mann-Whitney test to compare parity groups. Our results revealed that the only significant age-related differences were for the two mediolateral pelvic canal measurements in females, where individuals ≥51 years old (likely post-menopausal) had wider pelvic canals than the younger individuals, including those who would be considered advanced maternal age (≥35 years). The only parity-related difference was in the AP outlet, which was wider in parous individuals. There were no significant age-related differences in the male sample. We conclude that age-related pelvic remodeling is unlikely to be the reason for the higher incidence of c-sections in advanced maternal age individuals. Why the female pelvic canal expands mediolaterally post-menopause and anteroposteriorly after childbirth both require further exploration.

PURPOSE: To investigate the added value of directly observing sacroiliac (SI) diastasis with a modified examination under anaesthesia (EUA) protocol, including obturator inlet SI joint projections, in patients with anterior-posterior compression (APC) pelvic ring injuries. METHODS: This prospective cohort study, conducted in a level-1 trauma centre in 2017–2024, included patients > 18 years old with an APC injury, who underwent the modified EUA protocol. The modified protocol includes anterior-posterior projections of the anterior pelvis (as in the original EUA protocol), with additional obturator inlet projections of the SI joints. The primary outcomes were reclassification and detection of occult SI joint diastasis, either anterior or complete, following the modified EUA protocol. RESULTS: Thirty-five patients, with a mean age of 53, were included, 80% sustaining high-energy trauma. Following modified EUA, 23 (65.7%) of injuries were reclassified compared to classifications from CTs: 9 of 12 (75%) APC1s to APC2, 1 of 12 (8.3%) APC1s to APC3, and 13 of 23 (56.5%) APC2s to APC3. In 16 cases (45.7%), examining the SI joint during EUA enabled localisation of SI diastasis. Eleven patients of 13 (84.6%) with symphyseal diastasis less than the standard cut-off value of 2.5 cm had occult SI diastasis visible on the obturator inlet images. Four of 14 (28.5%) patients with rotational instability less than the standard cut-off value of 1.0 cm had complete SI diastasis visible on obturator inlet images. CONCLUSIONS: A modified EUA protocol, including obturator inlet projections of the SI joints, in patients with APC pelvic ring injuries has been proposed. This protocol allows for direct detection of SI joint diastasis that was not visible on the CT scans, allows for localization of SI joint diastasis, and reveals SI joint diastasis that would remain undetected if only the anterior ring was visualized.

This study aimed to determine how patient anatomical characteristics influence the technical demands of rectal cancer surgery and to assess whether robotic assistance can moderate these effects. A retrospective analysis was conducted on 131 individuals who underwent minimally invasive low anterior resection at Kobe University Hospital (laparoscopic: n = 74; robotic-assisted: n = 57). The interval between the start of pneumoperitoneum and rectal transection—representing the dissection phase—was used as a proxy for technical difficulty. Associations between dissection time and body mass index (BMI), pelvic inlet measurements, tumor size, and sex were evaluated in each surgical modality using simple linear regression. In laparoscopic procedures, prolonged dissection time was significantly associated with higher BMI, a shorter obstetric conjugate diameter, and male sex. None of these relationships were observed in the robotic-assisted cohort. Estimated blood loss was lower in the robotic group, whereas postoperative outcomes, recurrence patterns, and three-year survival rates showed no meaningful differences between the two approaches. Robotic-assisted rectal surgery maintained stable performance across a range of challenging anatomical conditions—including obesity, narrow pelvic dimensions, and male pelvic anatomy—suggesting that robotic platforms may buffer technical difficulties during the dissection phase. Evaluating surgery through a phase-specific lens may offer a valuable framework for understanding procedural complexity in minimally invasive rectal cancer treatment.

The pelvic inlet is one of the critical constraints within the relatively narrow birth canal for the passage of the fetal head. This study tested the hypothesis that the shape of the pelvic inlet differs between females and males, with the expectation that the female pelvic inlet is more elliptical than its male counterpart. Abdomino-pelvic computed tomography images from 600 cases, equally distributed by sex and age groups, were analyzed. Using 3D reconstruction, image processing, ellipse fitting, and a genetic algorithm, we evaluated whether the proposed measures of elliptical similarity in pelvic inlet shape varied by sex. Additionally, discriminant analysis was employed to assess the accuracy of sex determination based on these measures. The results demonstrated significant differences between the two sex groups for all proposed measures. Discriminant analysis achieved a maximum sex determination accuracy of 79.7%. These findings support the hypothesis that the female pelvic inlet has evolved to be more elliptical compared to the male pelvic inlet. If validated by future studies on diverse populations, this hypothesis may gain broader scientific acceptance.

Immediate posterior pelvic ring stabilization is the prerequisite for pelvic packing. In patients "in extremis", often no adequate positioning or imaging is available. Percutaneous application of a stabilizing K-wire or even a screw at the posterior pelvic ring can give adequate stability without an increased risk damage to surrounding structures, when respecting classical landmarks. In 10 human adult whole-body cadavers, a percutaneous application of a 2.8 mm K-wire was performed without image intensification. Only after insertion, standard a.p., inlet, and outlet imaging was performed to confirm wire positioning. The classical entry point for iliosacral screw fixation was used. An Arcadis© Orbic 3D C-arm (SIEMENS, Solothurn, Switzerland) was used for final control. In 16 of 20 hemipelves (80%), in all three standard radiographic planes, the K-wire was in the expected anatomic position. Malposition was observed as usually too anterior positioning of the wire in relation to the sacrum. Using standard landmarks, percutaneous application of K-wires into the posterior pelvic ring without intraoperative imaging was found to be feasible and resulted in few mal-placements as confirmed by post-insertion radiographs. The complication rate is comparable to mal-placement of pelvic C-clamp pins. This technique is feasible in patients in extremis.

Background and Objectives: Perineal wound complications and pelvic fluid collections or abscesses following proctectomy for Crohn's disease are a common cause of morbidity and might be mitigated by filling the pelvis and occluding the pelvic inlet with a flap. Alternative flap options can be considered when inadequate omentum is available and when avoiding myofasciocutaneous flaps. Materials and Methods: A retrospective review of our Crohn's proctectomy database was conducted to identify patients who underwent a non-omental or non-myofasciocutaneous local pedicle flap to their pelvis or pelvic exclusion using biological material during surgery. The techniques and outcomes of these alternative techniques are described in detail. Results: 228 patients underwent proctectomy for Crohn's disease during the 10-year study period. However, only six patients had their pelvis filled or pelvic inlet occluded using a non-omental, non-myofasciocutaneous local pedicled flap or biological material. The techniques identified included two sigmoid mesocolic flaps, one peritoneal, preperitoneal fat and falciform ligament flap, one perivesical fat flap, one Gerota's fat pad flap, and one bovine pericardial patch assisted pelvic exclusion. These flaps' clinicopathological and operative characteristics, surgical outcomes, and technical aspects are described. Conclusions: When greater omentum is unavailable or inadequate and myofasciocutaneous flaps need to be avoided, local pedicled flaps using a range of intra-abdominal tissues or biological material can be used to fill the pelvis or occlude the pelvic inlet after proctectomy for Crohn's disease. These techniques may help to prevent short and long-term complications associated with having a pelvic dead space.