Gender-Associated Differences in Sacral Morphology Do Not Affect Feasibility Rates of Transsacral Screw Insertion. Radioanatomic Investigation Based on Pelvic Cross-sectional Imaging of 200 Individuals

Contemplate iliosacral screw in patients with developmental dysplasia of the hip

OBJECTIVES

Our aim in the study was evaluating sacroiliac morphology in patients with DDH and its possible effect on appropriate iliosacral screw fixation.

DESIGN

Retrospective cohort study.

SETTING

Level of evidence 3.

PATIENTS/PARTICIPANTS

We evaluated the anteroposterior pelvis X-ray and pelvic CT scans of patients. We mainly divided the patients into two groups: DDH group (n:105) and control group (n:105).

INTERVENTION

The presence of the five qualitative characteristics of sacral dysplasia evaluated according to Route in both groups. The DDH group was divided into four subgroups according to the degree of hip dysplasia.

MAIN OUTCOME MEASUREMENT

The cross-sectional area, length of the osseous corridor, coronal and vertical angulation evaluated in both groups.

RESULTS

The DDH group also exhibited a significantly higher S1 coronal and axial angulation, lower S1 cross-sectional area and S1 iliosacral screw length than the control group (p:0.033, p:0,002, p:0.006, p:0,019, respectively). According to the Rout classification, 9% were normal, 31% transient, 58% dysplastic in the DDH group. 45.7% were normal, 38% transient, 17% dysplastic in the control groups. These differences between the groups were statistically significant (p < 0.001). When the DDH groups were evaluated within themselves; no statistically significant difference was observed in S1 and S2 cross-sectional area, S1 and S2 maximum estimated iliosacral screw length, S1 and S2 axial and coronal angles assessment.

CONCLUSION

Sacral dysplasia was more common, narrower and more angled osseous canal for the iliosacral screw was found in the DDH group. There was no relation between the degree of hip dysplasia and sacrum morphology in the DDH group. Thus, we suggest the surgeons be aware of iatrogenic injury even in constrained dysplastic hips.

Defining Sacral Dysmorphism: What Size Corridor Precludes Transsacral Screw Placement

OBJECTIVE

To determine what size S1-transsacral (TS) corridor is amenable to TS screw placement, as this is commonly used to identify sacral dysmorphism, and to determine if gender, ethnicity, or screw breach is associated with narrow corridors.

DESIGN

Retrospective review.

SETTING

Urban level-1 trauma center.

PATIENTS

Two hundred ninety patients with pelvic ring injuries and preoperative computed tomography (CT) scans.

INTERVENTION

Percutaneous posterior pelvic ring fixation.

MAIN OUTCOME MEASUREMENTS

The width of the S1-TS corridor was measured on the axial (inlet) and coronal (outlet) reformatted CT images. Patients with S1-TS screw fixation and postoperative CT scans were identified. Corridor size, gender, ethnicity, and screw breach were documented.

RESULTS

S1-TS screws were placed in 55 of the 290 patients. No S1-TS screws were placed in corridors less than 8 mm. Corridors of &lt;8 mm were present in 114 (39%) of the 290 patients and were not associated with gender or ethnicity. S1-TS screws placed in small (&lt;10 mm) versus large (≥10 mm) corridors did not have a detectable difference in screw breaches (5 of 8, 62% versus 19 of 47 40%; difference, 22%, 95% confidence interval -14% to 52%) or median (interquartile range) screw breach distance [3 mm (2.5-4.8) versus 3 mm (1.2-4.8); difference, 0.9 mm; confidence interval -1.6 to 2.2].

CONCLUSION

These data are useful for the standardization of sacral dysmorphism reporting based on corridor size. Screw breaches were common irrespective of TS corridor size, emphasizing the small degree of error allowed by this procedure.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Analysis of trans-sacral corridors in stabilization of fractures of the pelvic ring

Percutaneous screw fixation combined with pelvic reduction is a surgical technique used to stabilize fractures of the posterior pelvic ring. This is the standard surgical treatment of unstable posterior pelvic ring injuries. The primary goal of this treatment is an anatomic reduction and stable fixation. This has been shown to reduce pain and improve the patients' long-term well-being. The aim of this analysis was to determine the possible screw lengths and the positioning of the screws in the S1 and S2 sacral segments. A population of 697 pelvises from the Stryker Orthopaedic Modeling and Analytics database were analyzed. The dimensions of the S1 and S2 screw corridors were determined and after assessing for sacral dysmorphism, the correct screw placement was chosen to determine the necessary screw length for surgical treatment. The measurements of the screw lengths show a Gaussian distribution for the analyzed population. The percentage of dysmorphic pelvises for the S1 screw corridor was 31.3% and for the S2 corridor 8%. Average screw length for S1 was 163.8 ± 16.2 mm and for the S2 137.3 ± 9.5 mm. The results show that the S1/S2 axis cannot be used for a trans-sacral screw placement in every patient. The study shows that intraosseous screw corridors are present in 68.7% of the patients in the S1 position and in 92% at the S2 level where an intended implant can be placed fully intraosseous.

Navigated Transsacral Screw Fixation for the Treatment of Bilateral Sacral Insufficiency Fractures

Nondisplaced and minimally displaced sacral insufficiency fractures are increasingly being recognized as a cause of immobilizing low back pain in the elderly. These insufficiency fractures are most accurately diagnosed by visualizing sacral bone marrow edema on magnetic resonance imaging, which is the radiologic imaging modality with the highest sensitivity for identifying these fractures. Successful treatment options range from nonsurgical (eg, bed rest, pain medication, mobilization, antiosteoporotic medication, low-intensity-pulsed ultrasound, etc.) to surgical management (ie, sacroplasty and/or osteosynthesis with iliosacral screws or lumbosacral hinge fixation with or without application of reinforcing bone cement). The appropriate surgical treatment for frail subjects requires a less-invasive technique that establishes full weight-bearing stability for successful early remobilization of affected elderly and multimorbid individuals. Iliosacral screw osteosynthesis with a single C-arm is a common surgical technique for stabilizing the posterior pelvic ring after traumatic instabilities or fractures of the sacrum. Bilateral injuries are generally addressed from both sides of the pelvis. This article describes the surgical technique of 3D image-guided transsacral screw fixation for unilateral and bilateral nondisplaced sacral insufficiency fractures in the elderly using a single-sided approach, and specifies the associated preoperative and postoperative management. The procedure is illustrated in an instructional video that demonstrates step-by-step, how the navigated surgical procedure is performed.

Pelvic antropometric measurement in 3D CT for placement of two unilateral iliosacral S1 - 7.3 mm screws

PURPOSE

Stability of the dorsal pelvic ring is important for patient mobilisation and can be restored using several surgical procedures after fracture. Placement of percutaneous iliosacral screws is a reliable and minimal-invasive technique to achieve stabilisation of the dorsal pelvic ring by placement of two screws in the first sacral vertebra. Aim of this study was to evaluate 3D CT scans regarding the anatomical possibility to place two 7.3 mm iliosacral screws for fixation of the dorsal pelvic ring.

METHODS

3D CT datasets of 500 consecutive trauma patients with 1000 hemipelves of a mid-european level I trauma centre with or without pelvic injury were evaluated and measured bilaterally in this retrospective study.

RESULTS

One thousand hemipelvic datasets of 500 patients (157 females, 343 males) with a mean age of 49.7 years (18 to 95) were included in this study. Only 16 hemipelves (1.6%, 11 in females, 5 in males) in 14 patients (2.8%, 9 females = 5.73%, 5 males = 1.5%) showed too narrow corridors so that 7.3 mm screw placement would not be possible (p = 0.001). In women, too narrow corridors occurred 3.9 times as often as in men. Only two females showed this bilaterally.

CONCLUSION

The evaluation of 3D CT scans of the pelvis showed the importance of planning iliosacral screw placement, especially if two 7.3 mm screws are intended to be placed in the first sacral vertebra.