Percutaneous iliosacral screw fixation: early treatment for unstable posterior pelvic ring disruptions

Fluoroscopically assisted computer navigation enables accurate percutaneous screw placement for pelvic and acetabular fracture fixation

Percutaneous fixation of pelvic and acetabular fractures are technically demanding procedures, and high rates of screw misplacement and potential neurovascular complications have been reported. One hundred and sixty two screws from a prospectively collected database were analysed to evaluate the accuracy of a fluoroscopically assisted computer navigated technique to insert a cannulated screw to treat pelvic and acetabular fractures. Actual screw position and trajectory with the intraoperative surgical plan stored in the navigation computer. The actual screw position differed from the surgical plan by a mean of 3.9 mm, with a mean 1.4 degree difference in screw trajectory. Post operative CT analysis of patients showed 10 screws perforated cortical bone. Our results show that the use of computer navigation can aid in the accurate placement of percutaneous screws along a predefined plan. It is still possible to incorrectly place a screw and great care needs to be taken with the surgical plan and also to understand the complex anatomy of the bony pelvis.

Biomechanical study of four kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation: a finite element analysis

OBJECTIVE

To compare the biomechanical stability of four different kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation.

METHODS

Finite element models of unstable Tile type B and type C pelvic ring injuries were created in this study. Modelling was based on fixation with a single S1 screw (S1-1), single S2 screw (S2-1), two S1 screws (S1-2) and a combination of a single S1 and a single S2 screw (S1–S2). The biomechanical test of two types of pelvic instability (rotational or vertical) with four types of percutaneous fixation were compared. Displacement, flexion and lateral bend (in bilateral stance) were recorded and analyzed.

RESULTS

Maximal inferior translation (displacement) was found in the S2-1 group in type B and C dislocations which were 1.58 mm and 1.90 mm, respectively. Maximal flexion was found in the S2-1 group in type B and C dislocations which were 1.55° and 1.95°, respectively. The results show that the flexion from most significant angulation to least is S2-1, S1-1, S1-2, and S1–S2 in type B and C dislocations. All the fixations have minimal lateral bend.

CONCLUSION

Our findings suggest single screw S1 fixation should be adequate fixation for a type B dislocation. For type C dislocations, one might consider a two screw construct (S1–S2) to give added biomechanical stability if clinically indicated.

Comparison of two-transsacral-screw fixation versus triangular osteosynthesis for transforaminal sacral fractures

Transforaminal pelvic fractures are high-energy injuries that are translationally and rotationally unstable. This study compared the biomechanical stability of triangular osteosynthesis vs 2-transsacral-screw fixation in the repair of a transforaminal pelvic fracture model. A transforaminal fracture model was created in 10 cadaveric lumbopelvic specimens. Five of the specimens were stabilized with triangular osteosynthesis, which consisted of unilateral L5-to-ilium lumbopelvic fixation and ipsilateral iliosacral screw fixation. The remaining 5 were stabilized with a 2-transsacral-screw fixation technique that consisted of 2 transsacral screws inserted across S1. All specimens were loaded cyclically and then loaded to failure. Translation and rotation were measured using the MicroScribe 3D digitizing system (Revware Inc, Raleigh, North Carolina). The 2-transsacral-screw group showed significantly greater stiffness than the triangular osteosynthesis group (2-transsacral-screw group, 248.7 N/mm [standard deviation, 73.9]; triangular osteosynthesis group, 125.0 N/mm [standard deviation, 66.9]; P=.02); however, ultimate load and rotational stiffness were not statistically significant. Compared with triangular osteosynthesis fixation, the use of 2 transsacral screws provides a comparable biomechanical stability profile in both translation and rotation. This newly revised 2-transsacral-screw construct offers the traumatologist an alternative method of repair for vertical shear fractures that provides biplanar stability. It also offers the advantage of percutaneous placement in either the prone or supine position.

Anatomic Determinants of Sacral Dysmorphism and Implications for Safe Iliosacral Screw Placement

BACKGROUND

Upper sacral segment dysplasia increases the risk of cortical perforation during iliosacral screw insertion. Dysmorphic sacra have narrow and angled upper osseous corridors. However, there is no validated definition of this anatomic variation. We hypothesized that pelves could be quantitatively grouped by anatomic measurements.

METHODS

One hundred and four computed tomography (CT) scans and virtual outlet views of uninjured pelves were analyzed for the presence of the five qualitative characteristics of upper sacral segment dysplasia. CT scans were reformatted to measure the cross-sectional area, angulation, and length of the osseous corridor. Principal components analysis was used to identify multivariable explanations of anatomic variability, and discriminant analysis was used to assess how well such combinations can classify dysmorphic pelves.

RESULTS

The prevalences of the five radiographic qualitative characteristics of upper sacral segment dysplasia, as determined by two reviewers, ranged from 28% to 53% in the cohort. The rates of agreement between the two reviewers ranged from 70% to 81%, and kappa coefficients ranged from 0.26 to 0.59. Cluster analysis revealed three pelvic phenotypes based on the maximal length of the osseous corridor in the upper two sacral segments. Forty-one percent of the pelves fell into the dysmorphic cluster. The five radiographic qualitative characteristics of dysmorphism were significantly more frequent (p < 0.007) in this cluster. A combination of upper sacral coronal and axial angulation effectively explained the variance in the data, and an inverse linear relationship between these angles and a long upper sacral segment corridor was identified. A sacral dysmorphism score was derived with the equation: (first sacral coronal angle) + 2(first sacral axial angle). An increase in the sacral dysmorphism score correlated with a lower likelihood of a safe transsacral first sacral corridor. No subjects with a sacral dysmorphism score >70 had a safe transsacral first sacral corridor.

CONCLUSIONS

Sacral dysmorphism was found in 41% of the pelves. The major determinants of sacral dysmorphism are upper sacral segment coronal and axial angulation. The sacral dysmorphism score quantifies dysmorphism and can be used in preoperative planning of iliosacral screw placement.

Iliosacral screw insertion using CT-3D-fluoroscopy matching navigation

BACKGROUND

Percutaneous iliosacral screw insertion requires substantial experience and detailed anatomical knowledge to find the proper entry point and trajectory even with the use of a navigation system. Our hypothesis was that three-dimensional (3D) fluoroscopic navigation combined with a preoperative computed tomography (CT)-based plan could enable surgeons to perform safe and reliable iliosacral screw insertion. The purpose of the current study is two-fold: (1) to demonstrate the navigation accuracy for sacral fractures and sacroiliac dislocations on widely displaced cadaveric pelves; and (2) to report the technical and clinical aspects of percutaneous iliosacral screw insertion using the CT-3D-fluoroscopy matching navigation system.

METHODS

We simulated three types of posterior pelvic ring disruptions with vertical displacements of 0, 1, 2 and 3cm using cadaveric pelvic rings. A total of six fiducial markers were fixed to the anterior surface of the sacrum. Target registration error over the sacrum was assessed with the fluoroscopic imaging centre on the second sacral vertebral body. Six patients with pelvic ring fractures underwent percutaneous iliosacral screw placement using the CT-3D-fluoroscopy matching navigation. Three pelvic ring fractures were classified as type B2 and three were classified as type C1 according to the AO-OTA classification. Iliosacral screws for the S1 and S2 vertebra were inserted.

RESULTS

The mean target registration error over the sacrum was 1.2mm (0.5-1.9mm) in the experimental study. Fracture type and amount of vertical displacement did not affect the target registration error. All 12 screws were positioned correctly in the clinical series. There were no postoperative complications including nerve palsy. The mean deviation between the planned and the inserted screw position was 2.5mm at the screw entry point, 1.8mm at the area around the nerve root tunnels and 2.2mm at the tip of the screw.

CONCLUSION

The CT-3D-fluoroscopy matching navigation system was accurate and robust regardless of pelvic ring fracture type and fragment displacement. Percutaneous iliosacral screw insertion with the navigation system is clinically feasible.

Intra- and postoperative complications of navigated and conventional techniques in percutaneous iliosacral screw fixation after pelvic fractures: Results from the German Pelvic Trauma Registry

BACKGROUND

Percutaneous iliosacral screw placement following pelvic trauma is a very demanding technique involving a high rate of screw malpositions possibly associated with the risk of neurological damage or inadequate stability. In the conventional technique, the screw's correct entry point and the small target corridor for the iliosacral screw may be difficult to visualise using an image intensifier. 2D and 3D navigation techniques may therefore be helpful tools. The aim of this multicentre study was to evaluate the intra- and postoperative complications after percutaneous screw implantation by classifying the fractures using data from a prospective pelvic trauma registry. The a priori hypothesis was that the navigation techniques have lower rates of intraoperative and postoperative complications.

METHODS

This study is based on data from the prospective pelvic trauma registry introduced by the German Society of Traumatology and the German Section of the AO/ASIF International in 1991. The registry provides data on all patients with pelvic fractures treated between July 2008 and June 2011 at any one of the 23 Level I trauma centres contributing to the registry.

RESULTS

A total of 2615 patients were identified. Out of these a further analysis was performed in 597 patients suffering injuries of the SI joint (187×with surgical interventions) and 597 patients with sacral fractures (334×with surgical interventions). The rate of intraoperative complications was not significantly different, with 10/114 patients undergoing navigated techniques (8.8%) and 14/239 patients in the conventional group (5.9%) for percutaneous screw implantation (p=0.4242). Postoperative complications were analysed in 30/114 patients in the navigated group (26.3%) and in 70/239 patients (29.3%) in the conventional group (p=0.6542). Patients who underwent no surgery had with 66/197 cases (33.5%) a relatively high rate of complications during their hospital stay. The rate of surgically-treated fractures was higher in the group with more unstable Type-C fractures, but the fracture classification had no significant influence on the rate of complications.

DISCUSSION

In this prospective multicentre study, the 2D/3D navigation techniques revealed similar results for the rate of intraoperative and postoperative complications compared to the conventional technique. The rate of neurological complications was significantly higher in the navigated group.

CT-3D-fluoroscopy matching navigation can reduce the malposition rate of iliosacral screw insertion for less-experienced surgeons

OBJECTIVES

The aim of the present study was to determine whether 3-dimensional (3D) fluoroscopic navigation combined with a preoperative computer tomography (CT)-based plan could enable surgeons to perform safe and reliable iliosacral screw insertion despite their limited experience.

METHODS

Eight pelvises with surrounding soft tissue donated from embalmed cadavers were used. Kirschner wires with a diameter of 3 mm were placed across the ilia bilaterally into the S1 and S2 vertebrae by 4 orthopaedic trainees. In 4 specimens, wires were placed across the right ilium using conventional technique and the left ilium using the CT-3D-fluoroscopy matching navigation system. In 4 other specimens, wires were placed across the right ilium using the 3D-fluoroscopic navigation system and the left ilium using the CT-3D-fluoroscopy matching navigation system. A postoperative CT-based analysis of wire localization was performed. The number of wire insertions until the final position check, operation duration, and radiation time and dose were also evaluated.

RESULTS

The percentage of wires inserted correctly was higher in the CT-3D-fluoroscopy matching navigated group (100%) than in the conventional technique group (50%) and 3D-fluoroscopic navigation group (50%). The number of wire insertions and radiation time were significantly lower with both navigation systems than with the conventional technique, whereas there was no significant difference between the navigation systems. There were no significant differences in operation time and radiation dose among the 3 groups.

CONCLUSIONS

The CT-3D-fluoroscopy matching navigation system reduced the malposition rate of percutaneous iliosacral screw insertion when performed by less experienced surgeons.

Treatment of posterior pelvic ring disruptions using a minimally invasive adjustable plate

OBJECTIVE

Iliosacral (IS) screw fixation and posterior tension band plate (TBP) technique are two treatment alternatives for posterior pelvic ring injuries. However, IS screw fixation requires continuous fluoroscopic guidance for appropriate screw insertion and carries a risk of neurovascular injuries. TBP technique also has some disadvantages, including limited reduction potential, difficulty in precontouring the plate and a higher rate of symptomatic implants. To address these limitations, we introduced a minimally invasive adjustable plate (MIAP). This study aims to present the preliminary radiological and clinical results of posterior pelvic ring disruptions treated with MIAP.

METHODS

The MIAP conforms to the irregular shape of posterior pelvic ring and can be used without prebending. This plate has a role in reducing compressed or separated fractures/dislocations. Sixteen patients, including seven males and nine females, were treated with MIAP through a minimally invasive approach. The fracture patterns consisted of six Type B and ten Type C fractures according to OTA classification of fracture. Preoperative and postoperative radiography was taken to assess the fracture displacement and reduction quality. Postoperative rehabilitation programme was individualised and early exercise was encouraged. Patients were followed up and the functional outcome was evaluated based upon the scoring system proposed by Lindahl and associates.

RESULTS

All posterior pelvic ring disruptions were reduced and fixed with MIAP. The average duration of surgery was 49 min, the average radiation exposure was 6s, and the average blood loss was 80 mL for the treatment of posterior pelvic ring injuries. Overall radiological results of the reduction were excellent in eleven patients and good in five. The patients were followed up for 30 months on average. All fractures healed. The functional outcome was excellent in ten patients, good in four and fair in two. There were no iatrogenic neurovascular injuries, implant failures, irritative symptoms or pressure sores due to subcutaneous implantation.

CONCLUSION

Favourable clinical and radiological outcomes can be achieved in treating posterior pelvic disruptions with MIAP. This plate is effective in view of its simplicity, less radiation exposure, safety, minimal invasion and stable fixation.

Minimally invasive treatment for pubic ramus fractures combined with a sacroiliac joint complex injury

PURPOSE

Fractures of the pubic rami due to low energy trauma are common in the elderly, with an incidence of 26 per 100,000 people per year in those aged more than 60 years. The purpose of this study was to evaluate the clinical application of this minimally invasive technique in patients with pubic ramus fractures combined with a sacroiliac joint complex injury, including its feasibility, merits, and limitations.

METHODS

Fifteen patients with pubic ramus fractures combined with sacroiliac joint injury were treated with the minimally invasive technique from June 2008 until April 2012. The quality of fracture reduction was evaluated according to the Matta standard.

RESULTS

Fourteen cases were excellent (93.3 %), and one case was good (6.7 %). The fracture lines were healed 12 weeks after the surgery. The 15 patients had follow-up visits between four to 50 months (mean, 22.47 months). All patients returned to their pre-injury jobs and lifestyles. One patient suffered a deep vein thrombosis during the peri-operative period. A filter was placed in the patient before the surgery and was removed six weeks later. There was no thrombus found at the follow-up visits of this patient.

CONCLUSION

The minimally invasive technique in patients with pubic ramus fractures combined with a sacroiliac joint complex injury provided satisfactory efficacy.

The percutaneous stabilisation of the sacroiliac joint with hollow modular anchorage screws: a prospective outcome study

PURPOSE

The use of percutaneous iliosacral screw fixation as a treatment of sacroiliac joint pain has been reported to be successful. This study was a prospective single surgeon series to evaluate the short-term outcomes of patients who underwent percutaneous sacroiliac joint stabilisation.

METHODS

Between July 2004 and February 2011, 73 patients underwent percutaneous sacroiliac joint fusion in our unit. All patients completed a short form (SF)-36 questionnaire, visual analogue pain score and Majeed scoring questionnaire prior to treatment and at last follow-up.

RESULTS

55 patients (9 male and 46 female) completed follow-up. The average follow-up period was for 36.18 months (range 12-84). The mean preoperative SF-36 scores were 26.59 for physical health and 40.38 for mental health. The mean postoperative SF-36 scores were 42.93 for physical health and 52.77 for mental health. The mean visual analogue pain scores were 8.1 preoperative and 4.5 postoperative. The mean pelvic specific scoring were 36.9 preoperative and 64.78 postoperative. We noted that patients who had previous instrumented spinal surgery did significantly worse than those who had not. We had two nerve root-related complications.

CONCLUSION

We conclude that in selected patient group who respond positively to CT-guided injection, a percutaneous SI joint stabilisation is beneficial in effecting pain relief and functional improvement.

Intraoperative computed tomography with integrated navigation in percutaneous iliosacral screwing

BACKGROUND

Iliosacral screw fixation has generally been accepted as a treatment for unstable pelvic fractures with posterior sacroiliac joint disruption despite a 2-16% rate of screw malposition. The integration of an intraoperative computed tomography (iCT) with a navigation system was utilized in percutaneous sacroiliac screwing to provide an alternative.

METHODS

From October 2010 to November 2011, thirteen patients presented pelvic fractures with posterior ring disruption (lateral compression type 2-3 [n=12] and vertical shear type [n=1] by Young-Burgess Classification) and underwent percutaneous iliosacral screwing using an iCT integrated with navigation system. The perioperative data and radiographic outcomes of the patients were collected and analyzed.

RESULTS

Navigation times ranged from 10 to 45min (mean of 21.2±10.6min). Radiation exposure to the skin utilizing integrated navigation system ranged from 23.5 to 28.1mGy (mean of 26.4±1.5mGy), and the dose associated with examining the screw position ranged from 22.5 to 26.8mGy (mean of 25.5±1.1mGy). Effective dose of radiation ranged from 9.26 to 17.43mSv (mean of 13.16±2.52mSv). The iCT demonstrated iliosacral screws in adequate position (i.e., no penetration or encroachment of the neuroforamen or cord). No neurologic or vascular injury occurred in these cases.

CONCLUSIONS

An iCT with an integrated navigation system provided accuracy for percutaneous iliosacral screwing. In addition, the accumulated dose was minimized for surgeons. However, effective dose of radiation in iCT with an integrated navigation system group was higher than fluoroscopic-assisted iliosacral screwing in hands of the same group of surgeons. No neurologic complications occurred. The iCT with an integrated navigation system provided an alternative to percutaneous iliosacral screwing.

The invention of an iliosacral screw fixation guide and its preliminary clinical application

OBJECTIVE

To introduce an iliosacral screw fixation guide and evaluate its efficacy in fixation of sacroiliac joint fracture-dislocations.

METHODS

Between January 2011 and May 2011, eight patients (five men, three women) with sacroiliac joint fracture-dislocation underwent percutaneous iliosacral screw fixation with the assistance of this minimally invasive guide and under CT guidance. The patients, aged from 26 to 56 years (mean 32 years), had vertically unstable pelvic fractures. Before surgery, six patients who had displacement of >2 cm in their sacroiliac joints underwent skeletal traction on the femoral condyle. The inserted sites were marked out on the affected side of their buttocks after the best screw trajectory had been determined under CT control. The gear that controls the direction of the minimally invasive guide was adjusted according to the inserting angle determined by CT scans. A K-wire was inserted into the sacroiliac joint along the pilot sleeve of the guide, and a hollow screw (diameter 7.3 mm) was implanted into the sacroiliac joint along the K-wire.

RESULTS

All eight operations were successful on the first attempt. The operations lasted from 10 to 20 minutes (mean 14 minutes). Immediate CT scans confirmed that all the screws had been placed in the desired positions, none had penetrated the bones and the configuration of the sacroiliac joints had been satisfactorily restored and firmly fixed. No patient experienced numbness or radiating pain in the lower limbs during surgery. There were no postoperative vascular or neurological complications.

CONCLUSION

The minimally invasive guide can eliminate discrepancies resulting from the surgeon's own sensory input when inserting screws under the guidance of CT, making percutaneous iliosacral screw fixation more accurate, safe and simple.

Biomechanical research on anterior double-plate fixation for vertically unstable sacroiliac dislocations

OBJECTIVE

To determine the best method for anterior internal fixation by comparing the biomechanical characteristics of various anterior fixation methods for vertically unstable sacroiliac dislocations.

METHODS

Eight pelves with Tile C fracture with vertical loading were measured separately. Three- and two-hole anterior double plates were fixed at different angles and compared with sacroiliac screws.

RESULTS

For two-hole anterior double plates, with increasing angle, axial stability increases while lateral stability decreases. For three-hole plates with an angle of 60°, axial stability is clearly better when placed horizontally, while lateral stability shows no obvious differences.

CONCLUSION

For fixing sacroiliac dislocations, three-hole anterior double plates placed at about 60° produce excellent stability, which would be greatly increased if screws were added on the iliac side.

An efficient and accurate prediction of the stability of percutaneous fixation of acetabular fractures with finite element simulation

Posterior wall fracture is one of the most common fracture types of the acetabulum and a conventional approach is to perform open reduction and internal fixation with a plate and screws. Percutaneous screw fixations, on the other hand, have recently gained attention due to their benefits such as less exposure and minimization of blood loss. However their biomechanical stability, especially in terms interfragmentary movement, has not been investigated thoroughly. The aims of this study are twofold: (1) to measure the interfragmentary movements in the conventional open approach with plate fixations and the percutaneous screw fixations in the acetabular fractures and compare them; and (2) to develop and validate a fast and efficient way of predicting the interfragmentary movement in percutaneous fixation of posterior wall fractures of the acetabulum using a 3D finite element (FE) model of the pelvis. Our results indicate that in single fragment fractures of the posterior wall of the acetabulum, plate fixations give superior stability to screw fixations. However screw fixations also give reasonable stability as the average gap between fragment and the bone remained less than 1 mm when the maximum load was applied. Our finite element model predicted the stability of screw fixation with good accuracy. Moreover, when the screw positions were optimized, the stability predicted by our FE model was comparable to the stability obtained by plate fixations. Our study has shown that FE modeling can be useful in examining biomechanical stability of osteosynthesis and can potentially be used in surgical planning of osteosynthesis.

Computer-assisted periacetabular screw placement: Comparison of different fluoroscopy-based navigation procedures with conventional technique

The current gold standard for operatively treated acetabular fractures is open reduction and internal fixation. Fractures with minimal displacement may be stabilised by minimally invasive methods such as percutaneous periacetabular screws. However, their placement is a demanding procedure due to the complex pelvic anatomy. The aim of this study was to evaluate the accuracy of periacetabular screw placement assessing pre-defined placement corridors and comparing different fluoroscopy-based navigation procedures and the conventional technique. For each screw an individual periacetabular placement corridor was preoperatively planned using the planning software iPlan CMF(©) 3.0 (BrainLAB). 210 screws (retrograde anterior column screws, retrograde posterior column screws, supraacetabular ilium screws) were placed in an artificial Synbone pelvis model (30 hemipelves) and in human cadaver specimen (30 hemipelves). 2D- and 3D-fluoroscopy-based navigation procedures were compared to the conventional technique. Insertion time and radiation exposure to specimen were also recorded. The achieved screw position was postoperatively assessed by an Iso-C(3D) scan. Perforations of bony cortices or articular surfaces were analysed and the screw deviation severity (difference of the operatively achieved screw position and the preoperatively planned screw position in reference to the pre-defined corridors) was determined using image fusion. Using 3D-fluoroscopy-based navigation, the screw perforation rate (7%) was significantly lower compared to 2D-fluoroscopy-based navigation (20%). For all screws, the deviation severity was significantly lower using a 3D- compared to a 2D-fluoroscopy-based navigation and the conventional technique. Analysing the posterior column screws, the screw deviation severity was significantly lower using 3D- compared to 2D-fluoroscopy-based navigation. However, for the anterior column screw, the screw deviation severity was similar regardless of the imaging method. Despite the advantages of the 3D-fluoroscopy-based navigation, this method led to significantly longer total procedure and fluoroscopic times, and the applied radiation dose was significantly higher. Percutaneous periacetabular screw placement is demanding. Especially for posterior column screws, due to a lower perforation rate and a higher accuracy in periacetabular screw placement, 3D-fluoroscopy-based navigation procedure appears to be the method of choice for image guidance in acetabular surgery.

An anatomical update on the morphologic variations of S1 and S2

Although percutaneous fixation with iliosacral screws has been shown to be a safe and reproducible method for sacroiliac dislocation and sacral fractures, it is a technically demanding technique, and one of its contraindications is sacral anatomical variations and dysmorphism. The incidence and pattern of S1 and S2 anatomical variations were evaluated in 61 patients (35 women and 26 men) using magnetic resonance imaging of the sacrum in an attempt to explore the possible existence of groups of individuals in whom percutaneous sacroiliac fixation is difficult due to local anatomy. S1 and S2 dimensions in both the transverse and coronal planes were recorded and evaluated. In each individual, S1 and S2 dimensions both in the coronal and transverse planes were proportional, with S2 dimensions being 80% of those of S1 on average. Patients were separated into 4 groups based on the S1 and S2 body size and the asymmetry of dimensions in the transverse and coronal planes. In 48 patients (78.6%), dimensions in both planes were symmetrical despite the varying size of the S1 and S2 body. In 2 patients (3.3%) there was a combination of large transverse plane and small coronal plane dimensions, with large S1 and S2 body size. In 9 patients (14.8%), coronal plane dimensions were disproportionately smaller compared to those of the transverse plane, with a varying size of S1 and S2 body making effective sacroiliac screw insertion a difficult task. Thus, a preoperative imaging study, preferably computed tomography scan, of S1 and S2 body size and coronal plane dimensions and an intraoperative fluoroscopic control of S1 and S2 dimensions on the coronal plane are suggested for safe sacroiliac screw fixation.

Quantification of the upper and second sacral segment safe zones in normal and dysmorphic sacra

OBJECTIVES

To quantify the obliquity and dimensions of the upper and second sacral segment iliosacral screw safe zones and to determine the differences between normal and dysmorphic sacral morphology.

DESIGN

Retrospective cohort.

SETTING

University Level I trauma center.

PATIENTS/PARTICIPANTS

Fifty patients with pelvic computed tomography scans.

INTERVENTION

All sacra were characterized as normal or dysmorphic based on plain pelvic radiographs and previously described criteria. Multiple computed tomography scan reconstructions were viewed and manipulated simultaneously with 6 degrees of freedom to allow for custom visualization in any plane.

MAIN OUTCOME MEASUREMENTS

In each patient, a unique reconstruction plane was created perpendicular to the safe zone axis. The narrowest safe zone cross-sectional area was measured. Next, on simulated pelvic outlet and inlet views, safe zone obliquity and width were measured. Finally, the space available for a transverse screw was assessed. Measurements were performed for both upper and second sacral segment. Values for normal and dysmorphic safe zones were compared.

RESULTS

Sacral dysmorphism was identified in 22 patients. In these sacra, the upper sacral segment safe zone cross-section was 36% smaller than in normal sacra (P < 0.001). No transverse screws could be placed, but accommodating for the caudal to cranial obliquity (30° versus 21° in normals, P < 0.001) and posterior to anterior obliquity (15% versus 4% in normals, P < 0.001) of the safe zone, an iliosacral screw at least 75 mm in length could be placed safely in 91% of patients. A transverse screw could be placed in 75% of normal sacra. In the second segment safe zone, the cross-sectional area was more than twice as large in dysmorphic sacra compared to normals (220 mm versus 109 mm, P < 0.001). The obliquity was not different on either the inlet or outlet views between groups. A transverse screw could be placed at this level in 95% of those with dysmorphic sacra and in only 50% of normal sacra.

CONCLUSIONS

Sacral dysmorphism occurred in 44% of patients in this consecutive series. Many anatomic differences were consistently found between the two morphologies with clinical relevance to iliosacral screw placement. Specifically, the dysmorphic upper sacral segment safe zone is significantly smaller and more obliquely oriented but is still large enough to accommodate an iliosacral screw in nearly all patients. The second sacral segment safe zone is approximately transversely oriented in both sacral types but is more than twice as large in dysmorphic sacra. This segment may be a primary fixation opportunity in patients with sacral dysmorphism.

2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries--a case series

BACKGROUND

Screw fixation of pelvic ring fractures is a common, but demanding procedure and navigation techniques were introduced to increase the precision of screw placement. The purpose of this case series was the evaluation of screw misplacement rate and functional outcome of percutaneous screw fixation of pelvic ring disruptions using a 2D navigation system.

METHODS

Between August 2004 and December 2007, 44 of 442 patients with pelvic injuries were included for closed reduction and percutaneous screw fixation of disrupted pelvic ring lesions using an optoelectronic 2D-fluoroscopic based navigation system. Operating and fluoroscopy time were measured, as well as peri- and postoperative complications documented. Screw position was assessed by postoperative CT scans. Quality of live was evaluated by SF 36-questionnaire in 40 of 44 patients at mean follow up 15.5 +/- 1.2 month.

RESULTS

56 iliosacral- and 29 ramus pubic-screws were inserted (mean operation time per screw 62 +/- 4 minutes, mean fluoroscopy time per screw 123 +/- 12 seconds). In post-operative CT-scans the screw position was assessed and graded as follows: I. secure positioning, completely in the cancellous bone (80%); II. secure positioning, but contacting cortical bone structures (14%); III. malplaced positioning, penetrating the cortical bone (6%). The malplacements predominantly occurred in bilateral overlapping screw fixation. No wound infection or iatrogenic neurovascular damage were observed. Four re-operations were performed, two of them due to implant-misplacement and two of them due to implant-failure.

CONCLUSION

2D-fluoroscopic navigation is a safe tool providing high accuracy of percutaneous screw placement for pelvic ring fractures, but in cases of a bilateral iliosacral screw fixation an increased risk for screw misplacement was observed. If additional ramus pubic screw fixations are performed, the retrograde inserted screws have to pass the iliopubic eminence to prevent an axial screw loosening.

Superior gluteal artery injury during iliosacral screw placement due to aberrant anatomy

Percutaneous iliosacral screws are considered the standard of care for disruptions of the sacroiliac joint. This article describes a case of iatrogenic injury to the superior gluteal artery during iliosacral screw insertion and analyzes the possible reasons for this complication.A 32-year-old man diagnosed with an unstable pelvic ring injury underwent percutaneous fixation of the right sacroiliac joint. A 2-cm skin incision was made, and a straight cannulated awl was placed with the tip directly lateral to the S1 body. A guide wire was inserted and a partially threaded 6.5-mm cannulated screw with a washer was then placed over the guide wire and was found to be in excellent position. At this time, increased bleeding from the incision was observed. The incision was enlarged and dissection was carried down through the muscle. The bleeding vessel could not be visualized. Therefore, the wound was packed with sponges, and coil embolization of the right superficial gluteal artery was successfully performed.Analysis of the angiography reveled that our patient's superficial branch of the superior gluteal artery measured more than twice the average length reported in a previous anatomic study. We believe this is the first case of superior gluteal artery bleeding due to aberrant superior gluteal artery anatomy. When planning iliosacral screw insertion, the possibility of anatomical variance of the superior gluteal artery should be acknowledged and sought after in preoperative angiography, when available.

Computer-navigated iliosacral screw insertion reduces malposition rate and radiation exposure

Insertion of percutaneous iliosacral screws with fluoroscopic guidance is associated with a relatively high screw malposition rate and long radiation exposure. We asked whether radiation exposure was reduced and screw position improved in patients having percutaneous iliosacral screw insertion using computer-assisted navigation compared with patients having conventional fluoroscopic screw placement. We inserted 26 screws in 24 patients using the navigation system and 35 screws in 32 patients using the conventional fluoroscopic technique. Two subgroups were analyzed, one in which only one iliosacral screw was placed and another with additional use of an external fixator. We determined screw positions by computed tomography and compared operation time, radiation exposure, and screw position. We observed no difference in operative times. Radiation exposure was reduced for the patients and operating room personnel with computer assistance. The postoperative computed tomography scan showed better screw position and fewer malpositioned screws in the three-dimensional navigated groups. Computer navigation reduced malposition rate and radiation exposure.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Percutaneous fusion of the sacroiliac joint with hollow modular anchorage screws: clinical and radiological outcome

We reviewed 15 consecutive patients, 11 women and four men, with a mean age of 48.7 years (37.3 to 62.6), who between July 2004 and August 2007 had undergone percutaneous sacroiliac fusion using hollow modular anchorage screws filled with demineralised bone matrix. Each patient was carefully assessed to exclude other conditions and underwent pre-operative CT and MR scans. The diagnosis of symptomatic sacroiliac disease was confirmed by an injection of local anaesthetic and steroid under image intensifier control. The short form-36 questionnaire and Majeed's scoring system were used for pre- and post-operative functional evaluation. Post-operative radiological evaluation was performed using plain radiographs. Intra-operative blood loss was minimal and there were no post-operative clinical or radiological complications. The mean follow-up was for 17 months (9 to 39). The mean short form-36 scores improved from 37 (23 to 51) to 80 (67 to 92) for physical function and from 53 (34 to 73) to 86 (70 to 98) for general health (p = 0.037). The mean Majeed's score improved from 37 (18 to 54) pre-operatively to 79 (63 to 96) post-operatively (p = 0.014). There were 13 good to excellent results. The remaining two patients improved in short form-36 from a mean of 29 (26 to 35) to 48 (44 to 52). Their persistent pain was probably due to concurrent lumbar pathology. We conclude that percutaneous hollow modular anchorage screws are a satisfactory method of achieving sacroiliac fusion.

Closed reduction and iliosacral percutaneous fixation of unstable pelvic ring fractures

OBJECTIVE

To report clinical results of patients treated with closed reduction and percutaneous iliosacral screw fixation for unstable pelvic ring fractures.

MATERIALS AND METHODS

Retrospective study using medical records, images and late clinical assessment of all patients treated in our centre with percutaneous iliosacral screw fixation for unstable pelvic ring fractures, with a minimum follow-up of 12 months. Seventy-three patients with a mean age of 40.3 years old (range 14-70 years) were treated between July 1998 and December 2005. Seventy-one patients were included. Fractures types included 10 AO type B and 61 AO type C injuries. Forty-two patients had associated injuries. Mean follow-up was 31 months (12-96). Functional status was assessed using Majeed's grading score for pelvic fractures at final follow-up.

RESULTS

Sixty-nine patients obtained a satisfactory initial reduction. Two patients had transitory postoperative neurological deficit. Five patients presented hardware failure. Fifteen patients developed sacroiliac osteoarthritis during follow-up. Good and excellent functional results were observed in 66 patients at final follow-up. Five patients had bad results, one due to infection of an anterior pelvic plate and the others due to painful refractory sacroiliac osteoarthritis that required a sacroiliac fusion. Sixty-one (86%) patients were able to return to pre-injury occupation.

CONCLUSIONS

Good clinical results with a low and predictable rate of complications can be expected using closed reduction and percutaneous iliosacral screw fixation for unstable pelvic ring fractures.

A treatment protocol for abdomino-pelvic injuries

Background

Abdomino-pelvic injuries often present a challenge for the emergency department. Although literature reports several protocols on the treatment of abdomino-pelvic injuries aiming at defining the most advisable treatment line, optimal treatment is still controversial. This paper describes a protocol that has been used to treat abdomino-pelvic injuries in our hospital since 2002.

Materials and methods

In literature different protocol of abdomino-pelvic injuries are described and comparing them most of the difference are the timing of CT scan, the angiography and the laparotomy when treating a lesion of pelvic ring. If patient is haemodynamically instable and presents a lesion of pelvic ring our protocol suggest the simplest and fastest stabilization (pelvic external fixator) in emergency room and delay exam such as CT scan as second level exam. In the presence of an abdominal injury, with a positive focused assessment with sonography for trauma test, the first step should be a pelvic ring stabilization, as laparotomy decreases the abdominal pressure and reduces the tamponade effect on the retroperitoneum. According to presented protocol the angiography is not be a first choice treatment. This protocol was applied to 58 cases of abdomino-pevic injury with unstable pelvic lesions from October 2002 to December 2005. Mean injury severity score was 27.2 (CI  24.1–30.3).

Results

Five patients (8%) died, three due to haemorrhagic shock and two due to pulmonary embolization. Four patients (6.9%) had a partial or complete cauda equina syndrome, four patients (6.9%) complained of mild incontinence, whilst 1 (1.7%) complained of urinary retention with multiple cystitis. Two patients (3.4%) with retention and multiple cystitis, had a malunion and a painful non-union of the fracture. Seven patients (12.3%) had neurological impairment: 5 (8.6%) sciatic nerve palsy, 1 (1.7%) lumbosacral root lesions in a C2-type fracture and there was one case (1.7%) of inconstant lumbago with sciatic pain. Twelve patients reported different levels of sexual dysfunction (20.7%).

Conclusions

Although validation with a larger cohort is required, our preliminary clinical data are similar to, or better than, those reported in the most recent publications on this question, suggesting that this protocol could well reduce both the mortality rate and the long term complications of abdominopelvic injuries.

The epidemiology of pelvic ring fractures: a population-based study

BACKGROUND

The severity of pelvic ring fractures (PRFs) can range from minor injury with low-energy mechanism to high-energy injury causing prehospital death. The purpose of this study was to prospectively describe the comprehensive pelvic fracture occurrence in an inclusive trauma system.

METHODS

A 12-month prospective, population-based epidemiologic study was performed in the Hunter Region, New South Wales, Australia (population of 600,000, served by one Level I trauma center and 7 referring hospitals). Patient demographics, mechanism, injury severity, shock parameters, and outcomes were recorded prospectively. The database included all pelvic fractures from the region: high-energy pelvic fractures (HE-PRFs), low-energy pelvic fractures (LE-PRFs), and prehospital deaths (PD-PRFs).

RESULTS

The incidence of PRF in the trauma system was 23 per 100,000 persons (138 fractures). The incidences of HE-PRF and LE-PRF were each 10 per 100,000 persons, whereas there were 3 PD-PRFs per 100,000. HE-PRF compared with LE-PRF occurred predominantly in men (64% vs. 20%, p < 0.05), younger persons (41 +/- 3 vs. 83 +/- 1 years, p < 0.05), those who had a higher Injury Severity Score (23 +/- 3 vs. 6 +/- 1, p < 0.05), and those with lower blood pressure (111 +/- 1 mm Hg vs. 153 +/- 1 mm Hg, p < 0.05), but the inhospital mortality rate was not statistically different (15% vs. 8%, p = NS). The overall mortality of the cohort was 23% (60% of those were from the PD-PRF group). The PRF-related mortality was 7% (HE-PRF: 7%; LE-PRF: 2%; PD-PRF: 33%), which was always attributable to bleeding. The incidence of demonstrated pelvic fracture-related arterial bleeding was 1.3 per 100,000 persons per year.

CONCLUSIONS

LE-PRF and HE-PRF are equally frequent among hospital admissions. They represent two distinct demographic groups with similar mortality rate. Most PRF-related deaths occur prehospitally. Bleeding remains the primary cause of PRF-related mortality in all groups.

Percutaneous fixation of the pelvic ring: an update

With the development of systems of trauma care the management of pelvic disruption has evolved and has become increasingly refined. The goal is to achieve an anatomical reduction and stable fixation of the fracture. This requires adequate visualisation for reduction of the fracture and the placement of fixation. Despite the advances in surgical approach and technique, the functional outcomes do not always produce the desired result. New methods of percutaneous treatment in conjunction with innovative computer-based imaging have evolved in an attempt to overcome the existing difficulties. This paper presents an overview of the technical aspects of percutaneous surgery of the pelvis and acetabulum.

CT-Guided Stabilization for Chronic Sacroiliac Pain: A Preliminary Report

BACKGROUND

We evaluated a percutaneous, computed tomographic, stabilization from S1 to S2, for chronic painful sacroiliac disease. Our hypothesis was that this technique carries low morbidity, and may provide substantial relief of recalcitrant sacroiliac pain.

METHODS

17 patients had CT guided injection with local anesthesia and steroid to confirm the diagnosis. If symptoms recurred, they had a CT guided stabilization using only local anesthesia and conscious sedation. Outcome was evaluated with a visual analog scale. Univariate analysis and Spearman correlations used for analysis.

RESULTS

Pain improved from a mean of 8.3 pre-injection to 3.5 post-injection and remained at 3.3 at final follow up. Four patients had complete relief, 11 patients had significant pain relief, and two patients experienced little to no pain relief. There was a statistically significant difference between pre-injection and post injection pain scores (p < 0.0001), final and pre injection pain scores (p < 0.0001), but not between the post injection and final pain scores (p = 0.8906). A statistically significant correlation (p < 0.02) was found between final pain score and the difference between pre and post injection scores. There were no infections, hardware or technical complications.

CONCLUSIONS

This technique appeared effective in relieving the majority of confirmed sacroiliac pain and appeared to be lasting with few complications. While we did not confirm nor deny an arthrodesis with this technique, it appears that stabilization of the sacroiliac joint may have resulted in enough stability (e.g. alkalosis, mechanical restriction) that it relieved symptoms.

Die perkutane transiliosakrale Zugschraubenosteosynthese des hinteren Beckenrings

BACKGROUND

In recent years, the closed reduction and percutaneous fixation of posterior pelvic ring fractures by sacroiliac screws has become a well established treatment option for stabilization of posterior pelvic ring disruptions. Stable percutaneous pelvic ring fixation also implies a very low complication rate, e.g., in operative blood loss, wound healing, and operative time. To avoid malpositioning of the screws, sufficient reduction and radiologic visualization are essential. The surgical technique has been described in several studies; however, great importance is attached to the personal experience of the surgeon. Therefore, this study was conducted to establish a standard procedure that allows different surgeons a safe positioning of sacroiliac screws.

RESULTS

A total of 41 injuries of the posterior pelvic ring were stabilized with 73 sacroiliac lag screws inserted by 7 different surgeons using a standardized technique. In all cases adequate reduction of the fracture and radiologic visualization were achieved. No wound infections, no relevant bleedings, and no spiral fractures of screws were observed. In two cases malpositioning led to revision of the screws. Of interest, one case of S1 paresthesia resulting from a malpositioned screw could be revised. In contrast, two cases of screw loosening and one case of screw bending did not require further intervention.

CONCLUSION

We conclude that safe positioning of the sacroiliac screws was accomplished by all surgeons given a standardized technique. For safe insertion preparation of the patients, accurate visualization of the fracture zone, and potential closed reduction is always required.

Image guidance in pelvic and acetabular surgery--expectations, success and limitations

During the last decade navigation techniques in pelvic and acetabular surgery have been described. Nowadays, available techniques include CT-based navigation, 2D C-arm navigation and 3D C-arm navigation. The main indication is the navigated percutaneous SI screw fixation, but acetabular screw fixations are also reported. In this article, based upon a literature review and our own clinical experiences, the indications for and limitations of navigated techniques in pelvic and acetabular surgery are described.

Computer-assisted versus conventional surgery for insertion of 96 cannulated iliosacral screws in patients with postpartum pelvic pain

BACKGROUND

The purpose of this study was to assess the value of fluoroscopy-based computer-assisted surgery (CAS) for the insertion of iliosacral screws. The results of CAS were compared with the results of a conventionally operated prospective control group. Endpoints of this study were fluoroscopy time, guide wire insertion time, operation time and complication rate.

METHODS

The study group consisted of 24 patients with postpartum pelvic pain syndrome. All patients were treated with a stabilization of the pelvic ring by means of an anterior plate fixation and autologous tricortical bone graft as well as two iliosacral screws bilaterally. Consequently, the results of 48 versus 48 iliosacral screw fixations could be evaluated. Conventionally operated patients were turned from the supine to the prone position intraoperatively, whereas CAS operated patients were operated in the supine position. One surgeon performed all operations.

RESULTS

The fluoroscopy time in the CAS group was 0.7 minutes versus 1.8 minutes in the conventionally treated group (p < 0.01). The mean insertion time for four guide wires was 20.2 minutes in the CAS versus 19.4 minutes in the conventionally operated group (p = 0.6). The mean operation time in the CAS group was 97 minutes; 116 minutes in the conventional group (p = 0.03). In the CAS group one patient had pain and a sensory deficit of S2 postoperatively. The Fisher's exact test showed no difference in complication rate between the two groups (p = 0.26).

CONCLUSIONS

The fluoroscopy time is decreased with a factor 2.5 using CAS. Guide wire insertion time was similar in both groups. The reduction in operation time using CAS was due to fact that patients were operated in the supine position during the whole procedure. This study shows that CAS is a save technique for insertion of iliosacral screws.

Percutaneous Placement of Iliosacral Screws for Unstable Pelvic Ring Injuries: Comparison between One and Two C-arm Fluoroscopic Techniques

BACKGROUND

This study compares the efficacy and safety of percutaneous placement of iliosacral screws between one and two C-arm fluoroscope groups.

METHODS

This case series contains consecutive 18 unstable pelvic injuries, which were treated with percutaneous placement of iliosacral screws. A single orthopaedic surgeon (K.-T.P.) operated on all these patients. The patients were divided into two groups on the basis of the method of radiographic control. In group 1 (10 patients), iliosacral screws were introduced under the assistance of one C-arm fluoroscope. In group 2 (eight patients), percutaneous placements of iliosacral screws were performed under the control of two sets of fluoroscope.

RESULTS

There were neither clinical complications nor malpositioned screws in both groups. The median time from initial preparation to completion of the first screw insertion was 45.0 and 16.0 minutes for groups 1 and 2, respectively; the radiation exposure was 5.7 and 4.5 minutes, respectively. The differences between groups were statistically significant (p<0.001).

CONCLUSIONS

The use of two sets of fluoroscope provides a speedier method with less radiation exposure for percutaneous placement of iliosacral screws than the use of one set.

Sacroiliac joint dysfunction: evaluation and management

Sacroiliac joint dysfunction is believed to be a significant source of low back and posterior pelvic pain.

METHODS

To assess the clinical presentation, diagnostic testing, and treatment options for sacroiliac joint dysfunction, a systematic literature review was performed using MEDLINE.

RESULTS

Presently, there are no widely accepted guidelines in the literature for the diagnosis and treatment of sacroiliac instability. Establishing management guidelines for this disorder has been complicated by the large spectrum of different etiologic factors, the variability of patient history and clinical symptoms, limited availability of objective testing, and incomplete understanding of the biomechanics of the sacroiliac joint.

CONCLUSIONS

A reliable examination technique to identify the sacroiliac joint as a source of low back pain seems to be pain relief following a radiologically guided injection of a local anaesthetic into the sacroiliac joint. Most patients respond to non-operative treatment. Patients who do not respond to non-operative treatment should be considered for operative sacroiliac joint stabilization.

Operative Versorgungsstrategien beim Polytrauma mit Beckenfraktur

OBJECTIVE

In the management of multiply injured patients the question of the optimal time point for surgical treatment of individual injuries still remains open. Especially in severely injured patients with pelvic fractures, this decision differs between rapid surgical interventions in life-threatening situations or time-consuming reconstructive surgery. Besides the "early" operative treatment, i.e., within the first 24 h after trauma, the "late," i.e., definitive or secondary surgical fracture stabilization, exists. The following study represents a review of the current recommendations in the literature concerning the optimal time and fracture management of multiply injured patients with pelvic fracture.

METHODS

Clinical trials were systematically collected (MEDLINE, Cochrane, and hand searches), reviewed, and classified into evidence levels (1 to 5 according to the Oxford system).

RESULTS

According to the literature there is consensus on "early" operative stabilization of multiply injured patients with hemodynamically and mechanically unstable pelvic fractures, open pelvic fractures, or complex pelvic trauma. External fixation and the pelvic C-clamp are the methods of choice in emergency situations, whereas currently internal fracture fixation is only proposed in exceptional circumstances. In contrast, the point in time for the secondary definitive fracture stabilization remains controversially discussed. This discussion ranges from the postulation that extensive definitive fracture treatment be avoided during days 2-4 after trauma to the recommendation that definitive internal fixation of pelvic fractures be undertaken early, i.e., within the 1st week after trauma.

CONCLUSION

Basically, the principles of trauma management of multiply injured patients with life-threatening hemorrhage from mechanically unstable pelvic fractures are divided into two main time periods. On the one hand, there is the emergency stabilization of the pelvic ring as the most important goal within the acute period to control the bleeding, at least with extraperitoneal tamponade if necessary. On the other hand, once the hemorrhaging has been stopped, the "late" and definitive internal fracture stabilization of the pelvis should be performed depending on the fracture pattern.

Cyclic loading of sacroiliac screws in Tile C pelvic fractures

BACKGROUND

To investigate the stiffness and strength of completely unstable pelvic fractures fixated both anteriorly and posteriorly under cyclic loading conditions, the authors conducted a randomized, comparative, cadaveric study.

METHODS

In 12 specimens, a Tile C1 pelvic fracture was created. The authors compared the intact situation to anterior plate fixation combined with one or two sacroiliac screws. In 2,000 measurements, each pelvis was loaded with a maximum of 400 N. The translation and rotation stiffness of the fixations were measured using a three-dimensional video system. Furthermore, the load to failure and the number of cycles before failure were determined.

RESULTS

Both translation and rotation stiffness of the intact pelvis were superior to the fixated pelvis. No difference in stiffness was found between the techniques with one or two sacroiliac screws. However, a significantly higher load to failure and significantly more loading cycles before failure could be achieved using two sacroiliac screws compared with one screw.

CONCLUSION

Although the combination of anterior plate fixation combined with two sacroiliac screws is not as stable as the intact pelvis, in this study, embalmed aged pelves could be loaded repeatedly with physiologic forces. Given the fact that the average trauma patient is younger and given the fact that the quality (or grip) of the fixation was a significant covariable for longer endurance of the fixation, this suggests that direct postoperative weight bearing could be possible if these results are confirmed in further research.

Standard multiplanar fluoroscopy versus a fluoroscopically based navigation system for the percutaneous insertion of iliosacral screws: a cadaver model

OBJECTIVES

To compare the safety and efficiency of standard multiplanar fluoroscopy (StdFluoro) and virtual fluoroscopy (VirtualFluoro) for use in the percutaneous insertion of iliosacral screws.

DESIGN

: Human cadaver study comparing 2 imaging modalities during iliosacral screw insertion; imaging randomized from side to side.

SETTING

Bioskills laboratory in a medical school.

PARTICIPANTS

Twenty-nine embalmed whole human cadavers without prior hip or pelvic surgery.

INTERVENTION

Iliosacral screws were inserted into the S1 bodies using a percutaneous insertion technique. Screws were inserted on one side using StdFluoro, and on the other side, screws were placed using VirtualFluoro.

MAIN OUTCOME MEASUREMENTS

Time necessary for imaging preparation, screw insertion, and actual fluoroscopy were recorded. Accuracy and safety of screw placement was assessed using computed tomography and an anatomic dissection of the pelvis.

RESULTS

: Fifty-six of 58 iliosacral screws were placed within the desired bony corridor of the posterior pelvis. One screw placed using each method was inserted erroneously, but both were relatively minor deviations. There were no obvious injuries to major vessels or nerve roots. The total surgical time required for preparation of imaging and screw insertion averaged 7.3 minutes using StdFluoro and 6.7 minutes using VirtualFluoro (P = 0.4). Although the time necessary for screw insertion using VirtualFluoro averaged only 3.5 minutes, compared to 7.0 minutes for StdFluoro (P < 0.05), this time savings was offset by that required for application and calibration of tracking devices when using VirtualFluoro. The average fluoroscopy time using StdFluoro method was 26 seconds, whereas that for the VirtualFluoro was only 6 seconds (P < 0.01).

CONCLUSIONS

Most of the percutaneous iliosacral screws were safely inserted using StdFluoro and VirtualFluoro, and total surgical times were similar using both methods. As VirtualFluoro continues to evolve, improved efficiency in operative times may be expected. Currently, the most beneficial aspect of using VirtualFluoro during the insertion of percutaneous iliosacral screws appears to be significantly decreased use of fluoroscopy when compared to StdFluoro.

Inadvertent intraforaminal iliosacral screw placement despite apparent appropriate positioning on intraoperative fluoroscopy

We present the case of an intraforaminal iliosacral screw placed percutaneously with aid of C-arm using inlet, outlet, and lateral views of the pelvis. The iliosacral screw was placed above the S1 foramen on the outlet view, into the middle of S1 via the ala on the inlet view, and below the cortical shadow of the ala on the lateral view. The patient was neurologically intact postoperatively, but began to complain of severe radicular pain in the S1 distribution down to the foot within 1 week postsurgery. There was mild weakness of plantar flexion. Postoperative computed tomography scan showed that the iliosacral screw was within the S1 foramen. Because of the tangential nature of the S1 foramen, slight posterior placement of the screw into the S1 body and not into the promontory resulted in violation of the foramen despite it being above the cortical shadow on the outlet view.

Risks to the superior gluteal neurovascular bundle during percutaneous iliosacral screw insertion: an anatomical cadaver study

BACKGROUND

Iliosacral screws are a popular technique used to treat complicated injuries of the pelvis. It is well recognized that this technique entails some potentially disabling complications, including damage to vessels and lumbosacral nerves. The recommended insertion site for iliosacral screws into the S1 body lies along the posterior ilium between the greater sciatic notch and the iliac crest. The anatomy and course of the superior gluteal nerve and vessels have been described along the outer aspect of the posterior ilium. Injury to the superior gluteal nerve and vessels has been reported during pelvic surgery, including the insertion of iliosacral screws. The purpose of this study is to assess the risks of injury and proximity of percutaneously inserted iliosacral screws to the superior gluteal nerve and vessels using a cadaver model.

MATERIALS AND METHODS

Twenty-nine cadaver pelvises for a total of 58 sides (58 screws) were studied. Percutaneous iliosacral screws were placed into the first sacral bodies using multiplanar fluoroscopic guidance. The superior gluteal neurovascular bundle was then studied via a posterior dissection. Injury to the neurovascular bundle was noted if it occurred, and the distance between the screw head and the neurovascular bundle was measured. Distances from the screw head to the crista glutea, greater sciatic notch, and iliac crest were also measured.

RESULTS

The branching pattern of the superior gluteal nerve and vessels after they exit the greater sciatic notch demonstrated considerable variation, but was generally consistent with prior descriptions in most cases. Ten of 58 (18%) iliosacral screws caused injury to the superior branch of the superior gluteal nerve and vessels; 8 neurovascular bundles were impaled and 2 others were partly entrapped between the screw head and the ilium. The mean distance from the head of the iliosacral screws to the deep superior branches of the superior gluteal nerve and vessels was 9.1 mm (+/- 6.8 mm). The mean distances from the screw head to the crista glutea, sciatic notch, and iliac crest were 19.5 mm (+/- 4.9 mm), 33.0 mm (+/- 6.4 mm) and 50.3 mm (+/- 4.6 mm). Of the screws that caused superior gluteal nerve and vessels injury, all were within the "desired" area of insertion.

CONCLUSIONS

The deep superior branch of the superior gluteal nerve and vessels, which provides major blood and nerve supply to the G. medius and G. minimus, is at significant risk during the percutaneous placement of iliosacral screws even when "well placed" and soft tissue protecting cannulas are used. The clinical effects of these injuries remain poorly understood.

[Is implant removal after percutaneous iliosacral screw fixation of unstable posterior pelvic ring disruptions indicated?]

The aim of this study was to examine the indication for implant removal (IR) after percutaneous iliosacral screw fixation of unstable posterior pelvic ring disruptions by systematic literature analysis and clinical follow-up examination. Retrospective identification revealed 27 operatively stabilized patients [12 females, mean age: 35 years, ISS 22 points (range: 14-37)] between January 1996 and July 2001. Patient characteristics, AO classification, Hannover fracture scale pelvis, ISS, and DGU pelvis score points were analyzed. All cases showed a C-type lesion (C1:67%, C2:33%). A total of 21 patients were seen at follow-up, 12 with and 9 without IR. In ten cases with IR, clinical outcome improved after surgery according to the DGU pelvis score ( p=0.001, Wilcoxon's test). These mostly young patients also showed a better outcome compared with those cases without IR. Due to the good clinical results, implant removal seems to be beneficial for selected individual patients, especially when pain is present.

Biomechanical comparison of sacroiliac screw techniques for unstable pelvic ring fractures

OBJECTIVE

To determine the stiffness and strength of various sacroiliac screw fixations to compare different sacroiliac screw techniques.

DESIGN

Randomized comparative study on embalmed human pelvises.

MATERIALS AND METHODS

In 12 specimens, we created a symphysiolysis and sacral fractures on both sides. Each of these 24 sacral fractures was fixed with 1 of the following methods: 1 sacroiliac screw in the vertebral body of S1, 2 screws convergingly in S1, or 1 screw in S1 and 1 in S2. On the left and right side of a pelvis, different techniques were used. The pubic symphysis was not stabilized. We measured the translation and rotation stiffness of the fixations and the load to failure using a 3-dimensional video system.

RESULTS

The stiffness of the intact posterior pelvic ring was superior to any screw technique. Significant differences were found for the load to failure and rotation stiffness between the techniques with 2 screws and a single screw in S1. The techniques utilizing 2 screws showed no differences.

CONCLUSIONS

Based on the results of this study, we can conclude that a second sacroiliac screw in completely unstable pelvic fractures increases rotation stiffness and improves the load to failure.

Bilateral sacroiliac joint dislocation without associated fracture or anterior pelvic ring injuries

SI joint dislocations are serious injuries. They are often associated with posterior fractures or anterior ring disruptions. This case report documents the outcome of a patient with an uncommon injury involving bilateral SI joint dislocation without associated anterior pelvic injuries or posterior pelvic fracture.

[CT and fluoroscopy based navigation in pelvic surgery]

Navigation procedures based upon CT data were introduced into spine surgery in 1994. Since then the method has been used in other areas, such as joint replacement, reconstructive surgery and tumor surgery, because of its high precision and reduced radiation exposure. The original CT-based spine module can be adapted for pelvic surgery with the prerequisite, that the positioning of the fragments is identical in CT and at operation; otherwise, a new data set has to be acquired. The experience with CT-based navigation in pelvic surgery will be explained in the context of five percutaneous screw fixations and three tumor resections. The technique will be described. The fluoroscopy-based navigation has been used in trauma surgery since the late 1990 s. Since than the method has gained wide acceptance in the field of joint replacement and reconstructive surgery as well. Between June 2000 and December 2002 we performed 36 percutaneous screw fixations in the pelvis with postoperative X-ray and CT control. Thirty five of the 36 screws were placed correctly. In one screw an anterior cortex perforation of the sacrum was seen on CT, but without neurological consequences. Based upon our clinical experience we believe that CT-based navigation is indicated in screw fixations for minimally displaced pelvic injuries or dysplasia and, with increasing importance, in tumor surgery. Fluoroscopy based navigation with adequate image quality is the method of choice for SI screw fixations in traumatic or degenerative instabilities, especially if an update of the images is needed.