Accuracy of sacroiliac screw placement with and without intraoperative navigation and clinical application of the sacral dysmorphism score.

INTRODUCTION: Percutaneously-placed sacroiliac (SI) screws are currently the gold-standard fixation technique for fixation of the posterior pelvic ring. The relatively high prevalence of sacral dysmorphism in the general population introduces a high risk of cortical breach with resultant neurovascular damage. This study was performed to compare the accuracy of SI screw placement with and without the use of intraoperative navigation, as well as to externally validate the sacral dysmorphism score in a trauma patient cohort. PATIENTS AND METHODS: All trauma patients who underwent sacroiliac screw fixation for pelvic fractures at a level 1 trauma centre over a 6 year period were identified. True axial and coronal sacral reconstructions were obtained from their pre-operative CT scans and assessed qualitatively and quantitatively for sacral dysmorphism - a sacral dysmorphism score was calculated by two independent assessors. Post-operative CT scans were then analysed for breaches and correlated with the hospital medical records to check for any clinical sequelae. RESULTS: 68 screws were inserted in 36 patients, most sustaining injuries from road traffic accidents (50%) or falls from height (36.1%). There was a male preponderance (83.3%) with the majority of the screws inserted percutaneously (86.1%). Intraoperative navigation was used in 47.2% of the patient cohort. 30.6% of the cohort were found to have dysmorphic sacra. The mean sacral dysmorphism scores were not significantly different between navigated and non-navigated groups. Three cortical breaches occurred, two in patients with sacral dysmorphism scores >70 and occurring despite the use of intraoperative navigation. There was no significant difference in the rates of breach between navigated and non-navigated groups. None of the breaches resulted in any clinically observable neurovascular deficit. CONCLUSION: The sacral dysmorphism score can be clinically applied to a cohort of trauma patients with pelvic fractures. In patients with highly dysmorphic sacra, reflected by high sacral dysmorphism scores, intraoperative navigation is not in itself sufficient to prevent cortical breaches. In such patients it would be prudent to consider instrumentation of the lower sacral corridors instead.

A rare case of pelvic bone duplication.

Iliac bone malformations are rare and result from early disturbance of the genetic and epigenetic processes that come together to form the pelvic girdle. We report the case of a 5-month-old boy found to have a duplication of the ilium and describe the likely causes of this very rare malformation.

Use of the S3 Corridor for Iliosacral Fixation in a Dysmorphic Sacrum: A Case Report.

CASE: The S1 and S2 corridors are the typical osseous pathways for iliosacral screw fixation of posterior pelvic ring fractures. In dysmorphic sacra, the S1 screw trajectory is often different from that in normal sacra. We present a case of iliosacral screw placement in the third sacral segment for fixation of a complex lateral compression type-3 pelvic fracture in a patient with a dysmorphic sacrum. CONCLUSION: In patients with dysmorphic sacra and unstable posterior pelvic ring fractures or dislocations, the S3 corridor may be a feasible osseous fixation pathway that can be used in a manner equivalent to the S2 corridor in a normal sacrum.

Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves.

BACKGROUND: Percutaneous iliosacral screw placement is the standard procedure for fixation of posterior pelvic ring lesions, although a transsacral screw path is being used more frequently in recent years owing to increased fracture-fixation strength and better ability to fix central and bilateral sacral fractures. However, biomorphometric data for the osseous corridors are limited. Because placement of these screws in a safe and effective manner is crucial to using transsacral screws, we sought to address precise sacral anatomy in more detail to look for anatomic variation in the general population. QUESTIONS/PURPOSES: We asked: (1) What proportion of healthy pelvis specimens have no transsacral corridor at the level of the S1 vertebra owing to sacral dysmorphism? (2) If there is no safe diameter for screw placement in the transsacral S1 corridor, is an increased and thus safe diameter of the transsacral S2 corridor expected? (3) Are there sex-specific differences in sacral anatomy and are these correlated with known anthropometric parameters? METHODS: CT scans of pelves of 280 healthy patients acquired exclusively for medical indications such as polytrauma (20%), CT angiography (70%), and other reasons (10%), were segmented manually. Using an advanced CT-based image analysis system, the mean shape of all segmented pelves was generated and functioned as a template. On this template, the cylindric transsacral osseous corridor at the level of the S1 and S2 vertebrae was determined manually. Each pelvis then was registered to the template using a free-form registration algorithm to measure the maximum screw corridor diameters on each specimen semiautomatically. RESULTS: Thirty of 280 pelves (11%) had no transsacral S1 corridor owing to sacral dysmorphism. The average of maximum cylindrical diameters of the S1 corridor for the remaining 250 pelves was 12.8 mm (95% CI, 12.1-13.5 mm). A transverse corridor for S2 was found in 279 of 280 pelves, with an average of maximum cylindrical diameter of 11.6 mm (95% CI, 11.3-11.9 mm). Decreasing transsacral S1 corridor diameters are correlated with increasing transsacral S2 corridor diameters (R value for females, -0.260, p < 0.01; for males, -0.311, p < 0.001). Female specimens were more likely to have sacral dysmorphism (defined as a pelvis without a transsacral osseous corridor at the level of the S1 vertebra) than were male specimens (females, 16%; males, 7%; p < 0.003). Furthermore female pelves had smaller-corridor diameters than did male pelves (females versus males for S1: 11.7 mm [95% CI, 10.6-12.8 mm] versus 13.5 mm [95% CI, 12.6-14.4 mm], p < 0.01; and for S2: 10.6 mm [95% CI, 10.1-11.1 mm] versus 12.2 mm [95% CI, 11.8-12.6 mm ], p < 0.0001). CONCLUSIONS: Narrow corridors and highly individual, sex-dependent variance of morphologic features of the sacrum make transsacral implant placement technically demanding. Individual preoperative axial-slice CT scan analyses and orthogonal coronal and sagittal reformations are recommended to determine the prevalence of sufficient-sized osseous corridors on both levels for safe screw placements, especially in female patients, owing to their smaller corridor diameters and higher rate of sacral dysmorphism.

Nail-Patella Syndrome: clinical and molecular data in 55 families raising the hypothesis of a genetic heterogeneity.

Nail-Patella Syndrome (NPS) is a rare autosomal dominant condition comprising nail and skeletal anomalies. Skeletal features include dysplastic patellae and iliac horns, as well as scapula and elbow dysplasia. Nephropathy and glaucoma or intra-ocular hypertension can sometimes be present. NPS is due to variants affecting function in LMX1B, which encodes a LIM-homeodomain protein critical for limb, kidney and eye development. We describe the phenotype and the molecular data of 55 index patients and their 39 relatives presenting with typical NPS. We identified 38 different LMX1B anomalies, 19 of which were not reported before. In our series, 9% of families are not carriers of a LMX1B genomic alteration after extensive study of the coding and non-coding regions of the gene. One of the families showed no linkage to the LMX1B locus, raising the hypothesis of a genetic heterogeneity.

The surgical outcome and the surgical strategy of percutaneous endoscopic discectomy for recurrent disk herniation.

STUDY DESIGN: A retrospective analysis. OBJECTIVE: To present the surgical outcome of percutaneous endoscopic discectomy (PED) for recurrent herniated intervertebral disk disease (HIVD) and to suggest a surgical strategy. SUMMARY OF BACKGROUND DATA: Revision discectomy is technically demanding because of the scar tissue, unclear anatomic planes, and retraumatization to the posterior structures. Although open microdiscectomy is a standard method, endoscopic techniques have emerged as a surgical alternative with comparable results. PED was performed with either the transforaminal (PETD) or the interlaminar approach (PEID). Previous reports have shown the surgical outcomes of PETD or PEID for recurrent HIVD, but the application of each approach was not addressed clearly. METHODS: Consecutive 26 patients (M:F=16:10, mean age 53.1±12.4 y), who underwent PED for recurrent HIVD, were enrolled. The previous operation was an open discectomy in 22, a PETD in 2, and a PEID in 2 patients. PETD was considered preferentially, if it was feasible (n=11), because of the scar tissue formed by the previous operation. PEID was chosen (n=15) because of a high iliac crest (8), high canal compromise (3), high-grade inferior migration (2), and narrow neural foramen (2). All patients were followed up for 19.3±11.3 months. RESULTS: In all patients, the recurrent disk material was removed successfully, and conversion to an open surgery was not necessary. Postoperative magnetic resonance imaging revealed that the ruptured disk was removed successfully in all cases. A favorable outcome (excellent or good outcome by MacNab's criteria) was achieved in 21 patients (81%). Re-recurrence occurred in 2 patients at 6 and 12 months postoperatively. Risk factors for an unfavorable outcome were not found in the present study (P>0.05). CONCLUSIONS: The relevant utilization of updated surgical techniques may be helpful in overcoming the difficulty of revision surgery.

The pelvic digit anomaly in a patient with multiple fractures: does it mimic the fracture?

Pelvic digit is a rare congenital anomaly where bone develops in the soft tissue adjacent to normal skeletal bone. Pelvic digits are most often associated with the ilium but may also pseudoarticulate with other pelvic bones or the abdominal wall. Its importance lies in its differentiation from acquired abnormalities due to trauma such as myositis ossificans and avulsion injuries of pelvis. In this article, we present a case of pelvic digit with multiple fractures. To avoid unnecessary investigation methods and treatment, this entity should be kept inmindwhen an atypical bone structure is noted around the pelvis.