Irreducible Overlapping Pubic Symphysis Dislocation Managed with Distraction Osteotomy of the Contralateral Superior Pubic Ramus: A Rare Case Report

Introduction: Overlapping pubic symphysis dislocation (OPSD) or a locked pubic symphysis is a compression of the pelvic ring with the intact pubis trapped into the contralateral obturator foramen. Reduction can be difficult and contralateral suprapubic osteotomy is a good way to address the irreducible OPSD. The technique has only been discussed thrice in the available literature. Case Report: We report the case of a 26-year-old man who had his right pubic ramus entrapped within the contralateral obturator foramen, having an overlap of >4 cm with associated ipsilateral sacroiliac joint (SI joint) disruption and urethral injury. When all the maneuvers of closed and instrumented open reduction failed, we performed a superior pubic ramus osteotomy on the left side and unlocked the incarcerated right pubic ramus. The osteotomy site was stabilized with a 6-hole recon plate and SI joint was stabilized with a 6.5mm percutaneous sacroiliac screw. The patient underwent delayed urethral repair at 10 weeks after the index surgery. At 3-year follow-up, the patient did not report any pubic discomfort, urinary and sexual problems. Conclusion: Locked OPSD is a rare injury and is frequently associated with sacroiliac and urethral injuries. Distraction osteotomy of the contralateral superior pubic ramus is a viable option for irreducible cases. Keywords: Lateral compression injury, locked symphysis pubis, superior pubic ramus osteotomy, overlapping pubic symphysis dislocation.

Pelvic Response of a Total Human Body Finite Element Model During Simulated Injurious Under Body Blast Impacts

Military operations in Iraq and Afghanistan have resulted in the increased exposure of military personnel to explosive threats. Combat-related pelvic fractures are a relatively new battlefield injury that pose a serious threat to military personnel. Injury prediction for these events continues to be a challenge due to the limited availability of blast-specific test studies and the use of established automotive-based injury criteria that do not directly translate to combat-related exposures. The objective of this study is to evaluate the pelvic response of the Global Human Body Models Consortium (GHBMC) 50th percentile detailed male model (v4.3) in under body blast (UBB) loading scenarios. Nine simulations were conducted with mild or enhanced threat levels, and nominal or obtuse occupant positions. Cross-sectional force outputs from the superior pubic ramus (SPR), ilium, and sacroiliac (SI) regions were evaluated using previously developed injury risk curves. Additionally, maximum principal strain (MPS) data was extracted from the pelvic cortical bone elements. Results showed that shear force was the best predictor of fracture for the ischial and SI regions, while axial force was the best predictor for the SPR region. These outcomes were consistent with the load path of the simulated UBB events. The obtuse posture had higher peak force values for injurious and non-injurious outcomes for the SPR and SI region. The nominal posture had higher peak force values for non-injurious outcomes in the ischial region. These outcomes were supported by the MPS response present in these postures.

Surgical management of chronic pelvic instability following periacetabular osteotomy nonunion

Introduction: Periacetabular osteotomy (PAO) is an established treatment for symptomatic acetabular dysplasia in skeletally mature individuals without arthritis. Pelvic nonunion and associated stress fractures are under-reported. Nonunited stress fractures can cause continued buttock pain and pelvic instability. The aim of this study is to report on our experience managing patients with ongoing pain following nonunion of PAO. Patients and methods: 8 patients presented to a tertiary referral pelvic service with symptomatic PAO nonunion between 2015-2018. All patients underwent open reduction internal fixation of the superior pubic ramus nonunion, with ipsilateral iliac autograft, at an average of 48.1 (15–82) months following initial osteotomy. Demographic and perioperative data were recorded. Follow-up was on average to 9.9 months, once union was confirmed radiographically. Results: All patients were female and average age was 31.8 (18–41) years. In 7/8 (87.5%) patients a modified Stoppa approach was successfully utilised. 1 patient required an ilioinguinal approach due to the amount of rotational correction. All patients went on to union at the superior pubic ramus and reported improvement in mechanical symptoms. 5/8 (62.5%) patients were noted to develop union of the posterior column or inferior pubic ramus stress fracture indirectly. 2/8 (25%) patients developed progression of intra-articular pain, despite restoration of pelvic stability. 1 patient required intraoperative transfusion due to femoral vein injury. There were no other complications seen in this series. Conclusions: To our knowledge, this is the largest case series of surgically managed PAO nonunion. Pelvic instability resulting from nonunion and stress fracture can be satisfactorily addressed by mobilising, grafting and plating the nonunion at the superior pubic ramus. The modified Stoppa approach is suitable in most cases, allowing excellent exposure whilst minimising the insult to soft tissues. The altered anatomy of the pelvis following PAO should be anticipated to reduce the risk to nearby neurovascular structures.

Integrity of the pectineal ligament in MRI correlates with radiographic superior pubic ramus fracture displacement

Background Estimating the stability of pelvic lateral compression fractures solely by static radiographs can be difficult. In this context, the role of anterior pelvic soft tissues as potential secondary stabilizer of the pelvic ring has hardly been investigated. Purpose To correlate the initial radiographic appearance of the pubic ramus fracture with the integrity of the pectineal ligament, a strong ligament along the pecten pubis. Material and Methods In total, 31 patients with a pelvic lateral compression fracture (AO/OTA 61- B1.1/B2.1) with 33 superior pubic ramus fractures and available post-traumatic radiographs (pelvis anteroposterior, inlet, outlet) and magnetic resonance imaging (MRI) of the pelvis with fat-suppressed coronal images were reviewed retrospectively. Radiographic superior pubic ramus fracture displacement was measured and correlated to the degree of MR-morphologic alterations of the pectineal ligament (grade 0 = intact, grade 3 = rupture). Results In the majority of fractures (72.7%), associated MR-morphologic alterations of the pectineal ligament were present. Radiographic displacement and MRI grading showed a strong positive correlation (Spearman rho = 0.783, P < 0.001). The sensitivity and specificity for a radiographic displacement of >3 mm on plain radiographs to detect a structural ligament lesion on MRI (grade 2 and higher) were 73% and 100%, respectively. Conclusion Radiographic displacement of superior pubic ramus fractures >3 mm is a strong indicator for a structural lesion of the pectineal ligament. Future studies should investigate the potential biomechanical importance of this ligament for pelvic ring stability.

Periacetabular osteotomy using three-dimensional cutting and reposition guides: a cadaveric study

The goal of periacetabular osteotomy (PAO) is to reorient the acetabulum in a more physiological position. Its realization remains challenging regarding the final position of the acetabulum. Assistance with custom cutting- and reorientation-guides would thus be very helpful. Our purpose is to present a pilot study on such guides. Eight cadaveric hemipelvis were scanned using CT. After segmentation, 3D models of each specimen were created, a PAO was virtually performed and reorientation of the acetabula were defined. A specific guide was designed aiming to assist in iliac, posterior column and superior pubic ramus cuts as well as in acetabulum reorientation. Furthermore, the acetabular position was planned. Three-dimensional printed guides were used to perform PAO using the modified Smith-Peterson approach. The post-operative CT images and virtually planned acetabulum reorientation were compared in terms of acetabular index (AC), lateral centre edge angle (LCE), acetabular anteversion angle (AcetAV). There was no intra-articular or posterior column fracture seen. Two cadavers showed very low bone quality with insufficient stability of fixation and were excluded from further analysis. Correlation between the post-operative result and planning of the six included cadavers revealed the following mean deviations: 5° (SD ±3°) for AC angle, 6° (SD ±4°) for LCE angle and 15° (SD ±11°) for AcetAV angle. The use of 3D cutting and reorientation blocks for PAO was possible through a modified Smith-Peterson approach and revealed accurate fit to bone, accurate positioning of the osteotomies and acceptable planned corrections in cadavers with good bone quality.