Percutaneous fixation of pelvic ring disruptions

Correlating preoperative imaging with intraoperative fluoroscopy in iliosacral screw placement

Background

Percutaneous iliosacral screw placement can successfully stabilize unstable posterior pelvic ring injuries. Intraoperative fluoroscopic imaging is a vital component needed in safely placing iliosacral screws. Obtaining and appropriately interpreting fluoroscopic views can be challenging in certain clinical scenarios. We report on a series of patients to demonstrate how preoperative computed tomography (CT) imaging can be used to anticipate the appropriate intraoperative inlet and outlet fluoroscopic views.

Materials and methods

24 patients were retrospectively identified with unstable pelvic ring injuries requiring operative fixation using percutaneous iliosacral screws. Utilizing the sagittal reconstructions of the preoperative CT scans, anticipated inlet and outlet angle measurements were calculated. The operative reports were reviewed to determine the angles used intraoperatively. Postoperative CT scans were reviewed for repeat measurements and to determine the location and safety of each screw.

Results

Preoperative CT scans showed an average inlet of 20.5° (7°–37°) and an average outlet of 42.8° (30°–59°). Intraoperative views showed an average inlet of 24.9° (12°–38°) and an average outlet of 42.4° (29°–52°). Postoperative CT scans showed an average inlet of 19.4° (8°–31°) and an average outlet of 43.2° (31°–56°). The average difference from preoperative to intraoperative was 4.4° (−21° to 5°) for the inlet and 0.45° (−9° to 7°) for the outlet. The average difference between the preoperative and postoperative CT was 2.04° (0°–6°) for the inlet and 2.54° (0°–7°) for the outlet.

Conclusion

There is significant anatomic variation of the posterior pelvic ring. The preoperative CT sagittal reconstruction images allow for appropriate preoperative planning for anticipated intraoperative fluoroscopic inlet and outlet views within 5°. Having knowledge of the desired intraoperative views preoperatively prepares the surgeon, aids in efficiently obtaining correct intraoperative views, and ultimately assists in safe iliosacral screw placement.

Level of evidence

IV, Retrospective case series.

CT-guided sacroiliac percutaneous screw placement in unstable posterior pelvic ring injuries: accuracy of screw position, injury reduction and complications in 71 patients with 136 screws

BACKGROUND

Sacroiliac-percutaneous-screw-placement (SPSP) for unstable-posterior-pelvic-ring-injuries (UPPRI) might be associated with severe neurovascular complications because of screw-mal-position. The aim of the present study was to analysis the effectivity of computer-tomography-guided (CTG)-SPSP including accuracy of screw-placement, quality of injury-reduction and documentation of perioperative-complications. Additionally, procedure-dependent radiation-dose and outcome should be analysed.

METHODS

A consecutive cohort of 71 patients with UPPRI was operated by CTG-SPSP at a single trauma level 1 hospital. 136 sacroiliac screws were inserted to S1 and S2. Postoperatively, by the use of a computerised-radiologic-work-station all screws were visualised three-dimensionally. Their distancesmin to the sacral-borders in anterior-posterior and cranio-caudal direction as well as to the neuroforamen S1/S2 were determined. After CTG-SPSP, injury-dislocation in anterior-posterior and cranio-caudal direction was quantified. Local and general complications were documented during the 30-day-period. In 55 patients (77.5%) a follow-up-investigation (29.1±19.1 months) was performed.

RESULTS

132 screws (97.1%) were placed completely intraosseous, 3 screws (2.2%) perforated up to 1.0 mm (n(S1)=one screw; n(S2)=two screws), and one screw (0.7%) extended 2.2 mm into the S2-neuroforamen without contact to neural structures. Postoperative dislocationanterior-posterior was 1.3±0.9 mm and dislocationcranio-caudal 1.5±0.9 mm. No procedure-associated-complication was observed. Operation time showed a significant "learning curve" during the six-year study period (initially: 88.6±60.3 min; finally: 44.3±24.6 min). Perioperative effective-radiation-dose for patientsmale was 5.9±3.1 mSv and for patientsfemale 8.7±4.5 mSv. All injuries healed and 33 patients (46.5%) had metal removal after 11.0 (±4.9) months. Only two (5.0%) out of 40 patients complained persistent UPPRI-related pain so they were not able to restart work.

CONCLUSIONS

The CTG-SPSP is a safe procedure for UPPRI-stabilisation especially in S1 but also in S2. Injury reduction was excellent and no procedure associated complications were observed.

Anatomical measurement and finite element study on screw channel parameter in percutaneous fixation of canulated screw for symphyseolysis

To provide anatomical basement for symphyseolysis treatment with percutaneous fixation of canulated screw, through anatomical measurement on pubic symphysis and the surrounding tissues, and conduct the finite element studies on screw channel parameters. 20 cases of normal pelvic specimens from embalmed adult cadavers were taken to measure the anatomical parameter of bony remark of pubic symphysis and the space between spermatic cord (round ligament of the uterus) and pubic tubercle. Anatomical measurement results showed that the narrowest diameter of the superior ramus of pubis was 9.127 ± 1.189 mm, distance between two pubic tubercles was 55.656 ± 3.780 mm, thickness of the upper pubic symphysis was 10.510 ± 0.814 mm, and distance between upper and lower pubic symphysis was 40.872 ± 1.211 mm; the distance between round ligament of the uterus and pubic tubercle was 4.408 ± 0.304 mm, and the distance between spermatic cord and pubic tubercle was 5.196 ± 0.251 mm. The angle between canulated screw guide pin and horizontal plane was 8.342 ± 2.152°, the one between guide pin and coronal plane was 5.236 ± 1.612°, and the distance from entry point to the outer edge of pubic tubercle was 10.023 ± 1.245 mm, which was measured by Mimics software. Percutaneous surgery at horizontal position was simulated on cadaver. And the screw was correctly placed in postoperative imaging examination. According to the anatomical data and finite element studies of screw channel parameter in percutaneous fixation of canulated screw for symphyseolysis, the method can improve the accuracy of screw placement and reduce complications.

Posterior approach in treating sacral fracture combined with lumbopelvic dissociation

Type III Denis fracture of the sacrum is rare clinically, constituting approximately 16% of all sacral fractures. Because it is often complicated with neurologic injuries, treatment is crucial and difficult. Several surgical options are available for the treatment of type III Denis sacral fracture with lumbopelvic dissociation. The authors report 21 patients admitted to the hospital from February 2002 to May 2012 who had type III Denis sacral fracture combined with lumbopelvic dissociation. All of the patients were treated with posterior sacral lamina decompression, sacral nerve root decompression, fracture reduction, an integrated lumbopelvic internal fixation system, and posterolateral fusion. The authors recorded pre- and postoperative complications, fracture reduction, bone graft healing, and improvements in neurologic function, according to the Gibbons grading standard. The average surgical time was 190 minutes (range, 170-210), and the average amount of intraoperative bleeding was 960 mL (range, 930-1500). No intraoperative complications occurred. Twelve patients had complete recovery of neurologic function; 5 patients showed great improvement except for foot drop and impaired lower limb sensation; and 4 patients showed no improvement in lower limb, bladder, and rectum function. Gibbons grade decreased from an average of 3.43±0.51 before surgery to 1.76±1.09 at the last follow-up. Deep infections were noted in 2 cases, and in 1 case, vertebral screw loosening was observed 1 year postoperatively. Surgical reduction with lumbopelvic fixation is an ideal method for treating type III Denis sacral fracture with neurologic injury and lumbopelvic dissociation.

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.

Technical and clinical outcome of percutaneous CT fluoroscopy-guided screw placement in unstable injuries of the posterior pelvic ring

PURPOSE

To evaluate technical success, complications, and effective dose in patients undergoing CT fluoroscopy-guided iliosacral screw placement for the fixation of unstable posterior pelvic ring injuries.

MATERIALS AND METHODS

Our retrospective analysis includes all consecutive patients with vertical sacral fractures and/or injury of the iliosacral joint treated with CT fluoroscopy-guided screw placement in our department from 11/2005 to 03/2013. Interventions were carried out under general anesthesia and CT fluoroscopy (10-20 mAs; 120 kV; 16- or 128-row scanner, Siemens Healthcare, Erlangen, Germany). Technical outcome, major and minor complications, and effective patient dose were analyzed.

RESULTS

We treated 99 consecutive patients (mean age 53.1 ± 21.7 years, 50 male, 49 female) with posterior pelvic ring instability with CT fluoroscopy-guided screw placement. Intervention was technically successful in all patients (n = 99). No major and one minor local complication occurred (1 %, secondary screw dislocation). General complications included three cases of death (3 %) due to pulmonary embolism (n = 1), hemorrhagic shock (n = 1), or cardiac event (n = 1) during a follow-up period of 30 days. General complications were not related to the intervention. Mean effective patient radiation dose per intervention was 12.28 mSv ± 7.25 mSv. Mean procedural time was 72.1 ± 37.4 min.

CONCLUSIONS

CT fluoroscopy-guided screw placement for the treatment of posterior pelvic ring instabilities can be performed with high technical success and a low complication rate. This method provides excellent intrainterventional visualization of iliac and sacral bones, as well as the sacral neuroforamina for precise screw placement by applying an acceptable effective patient dose.

The posterior approach to pelvic ring injuries: A technique for minimizing soft tissue complications

Surgical techniques and fixation strategies for the treatment of unstable posterior pelvic ring injuries continue to evolve. The safety of the posterior surgical approach in particular has been questioned due to historically high rates of wound related complications. More contemporary studies have shown lower infection rates, however concern still persists. These concerns for infection and wound necrosis have led, in part, to increased interest in closed reduction and percutaneous fixation for treatment of these injuries but an open posterior approach remains the optimal strategy in some injury patterns. We describe herein a modified posterior approach to the pelvis designed to minimize wound related complications and present our clinical results demonstrating wound complication rates consistent with contemporary publications.

Clinical results after different operative treatment methods of radial head and neck fractures: a systematic review and meta-analysis of clinical outcome

INTRODUCTION

There is no consensus on optimal treatment strategy for Mason type II-IV fractures. Most recommendations are based upon experts' opinion.

METHODS

An OVID-based literature search were performed to identify studies on surgical treatment of radial head and neck fracture. Specific focus was placed on extracting data describing clinical efficacy and outcome by using the Mason classification and including elbow function scores. A total of 841 clinical studies were identified describing in total the clinical follow-up of 1264 patients.

RESULTS

For type II radial head and neck fractures the significant best treatment option seems to be ORIF with an overall success rate of 98% by using screws or biodegradable (polylactide) pins. ORIF with a success rate of 92% shows the best results in the treatment of type III fractures and seem to be better than resection and implantation of a prosthesis. For this fracture type the ORIF with screws (96%), biodegradable (polylactide) pins (88%) and plates (83%) showed the best results. In the treatment of type IV fractures similar results could be found with a tendency of the best results after ORIF followed by resection and implantation of a prosthesis. If a prosthesis was implanted, the primary implantation seems to be associated with a better outcome after type III (87%) and IV (82%) fractures compared to the results after a secondary implantation.

DISCUSSION

Recommendations for surgical treatment of radial head and neck fractures according to the Mason classification can now be given with the best available evidence.

LEVEL OF EVIDENCE

IV.

Technique for reduction and percutaneous fixation of U- and H-shaped sacral fractures

We describe an early reduction and percutaneous fixation technique for isolated sacral fractures. Strong manual traction combined with manual counter-traction on the torso is used to disimpact the fracture. Transcondylar traction is then applied bilaterally and two ilio-sacral screws are inserted percutaneously on each side. Open reduction and fixation, with sacral laminectomy in patients with neurological abnormalities, remains the reference standard. Early reduction and percutaneous fixation ensures restoration of the pelvic parameters while minimising soft-tissue damage and the risk of infection. Decompression procedures can be performed either during the same surgical procedure after changing the installation or after a few days. These complex fractures warrant patient referral to specialised reference centres.

Parallel analysis of finite element model controlled trial and retrospective case control study on percutaneous internal fixation for vertical sacral fractures

BACKGROUND

Although percutaneous posterior-ring tension-band metallic plate and percutaneous iliosacral screws are used to fix unstable posterior pelvic ring fractures, the biomechanical stability and compatibility of both internal fixation techniques for the treatment of Denis I, II and III type vertical sacral fractures remain unclear.

METHODS

Using CT and MR images of the second generation of Chinese Digitized Human "male No. 23", two groups of finite element models were developed for Denis I, II and III type vertical sacral fractures with ipsilateral superior and inferior pubic ramus fractures treated with either a percutaneous metallic plate or a percutaneous screw. Accordingly, two groups of clinical cases that were fixed using the above-mentioned two internal fixation techniques were retrospectively evaluated to compare postoperative effect and function. Parallel analysis was performed with a finite element model controlled trial and a case control study.

RESULTS

The difference of the postoperative Majeed standards and outcome rates between two case groups was no statistically significant (P > 0.05). Accordingly, the high values of the maximum displacements/stresses of the plate-fixation model group approximated those of the screw-fixation model group. However, further simulation of Denis I, II and III type fractures in each group of models found that the biomechanics of the plate-fixation models became increasingly stable and compatible, whereas the biomechanics of the screw-fixation models maintained tiny fluctuations. When treating Denis III fractures, the biomechanical effects of the pelvic ring of the plate-fixation model were better than the screw-fixation model.

CONCLUSIONS

Percutaneous plate and screw fixations are both appropriate for the treatment of Denis I and II type vertical sacral fractures; whereas percutaneous plate fixation appears be superior to percutaneous screw fixation for Denis III type vertical sacral fracture. Biomechanical evidence of finite element evaluations combined with clinical evidence will contribute to our ability to distinguish between indications that require plate or screw fixation for vertical sacral fractures.

Intraosseous correction of misdirected cannulated screws and fracture malalignment using a bent tip 2.0 mm guidewire: technique and indications

Percutaneous pelvic screw placement is a technically demanding procedure. A precise intraosseous pathway must be prepared before screw placement into any osseous fixation pathway of the pelvis. Adjustments to a drill or guidewire become increasingly difficult as the instrument is advanced within the pelvis. We present a reliable and reproducible technique using a 2.0 mm guidewire that allows for correction of an initially misdirected drill within the pelvis. This technique also allows for manipulation and reduction of certain malaligned pelvic fractures prior to percutaneous cannulated screw placement. This technique does not substitute for poor surgical technique but is used to optimize the position of percutaneously placed pelvic screws.

An evaluation of three-dimensional image-guided technologies in percutaneous pelvic and acetabular lag screw placement

BACKGROUND

Percutaneous stabilization using three-dimensional (3D) navigation system is a promising treatment for pelvic and acetabular fractures. However, there are still some controversies regarding the use of 3D navigation to treat pelvic and acetabular fractures. The purpose of this study was to compare the Iso-C(3D) fluoroscopic navigation, standard fluoroscopy, and two-dimensional (2D) fluoroscopic navigation in placing percutaneous lag screws in pelvic specimens to better understand the merits of 3D navigation techniques.

METHODS

Fifty-four instrumentation procedures were performed in this study using six cadaveric pelvic specimens. Three groups were designated for different procedures and tests: group I, standard fluoroscopy; group II, 2D fluoroscopic navigation; and group III, Iso-C(3D) fluoroscopic navigation. Nine screws were placed in each pelvis, including four screws placed bilaterally through the ilium into S1 and S2 vertebrae, four screws placed bilaterally through anterior and posterior columns of acetabulum, and one screw placed through the pubic symphysis. 3D fluoroscopic techniques were evaluated to determine the accuracy of screw position, instrumentation time, and fluoroscopic time. The data were statistically analyzed using SPSS 13.0.

RESULTS

The malposition rate was 38.89%, 22.22%, and 0% in standard fluoroscopy, 2D fluoroscopic navigation, and Iso-C(3D) fluoroscopic navigation groups, respectively. There was no significant difference between standard fluoroscopy and 2D fluoroscopic navigation. Compared with Iso-C(3D) fluoroscopic navigation, there were significant differences (analysis of variance [ANOVA], P < 0.05). The mean instrumentation operating time using Iso-C(3D) fluoroscopic navigation technique was 15.4 ± 4.5 min. There were significant differences compared with standard fluoroscopy (31.5 ± 6.2 min) and 2D fluoroscopic navigation (26.3 ± 7.5 min; ANOVA, post hoc Scheffe, P < 0.01). The mean fluoroscopic time of Iso-C(3D) fluoroscopic navigation was 66 ± 4.8 min. Compared with standard fluoroscopy (132.8 ± 7.3 min) and 2D fluoroscopic navigation (47.7 ± 5.6 min), there were significant differences (ANOVA, post hoc least significant difference, P < 0.01).

CONCLUSIONS

In the present study, we compared Iso-C(3D) fluoroscopic navigation, 2D fluoroscopic navigation, and standard fluoroscopy. Iso-C(3D) fluoroscopic navigation showed a higher accuracy rate in positioning and a shorter instrumentation operating time. The fluoroscopic time was longer in Iso-C(3D) fluoroscopic navigation than that in standard fluoroscopy, indicating that radiation exposure can be moderately reduced in Iso-C(3D) fluoroscopic navigation operation, although the fluoroscopic time was the shortest in 2D fluoroscopic navigation.

Use of the obturator-outlet oblique view to guide percutaneous retrograde posterior column screw placement

In contrast to open reduction internal fixation, percutaneous fixation is a relatively new option for operative fixation of acetabular fractures. The techniques for percutaneous insertion of anterior and posterior column screws have been previously described. For technical aspects of retrograde percutaneous posterior column screws, much attention has been paid to the proper start point. However, descriptions of proper trajectory and end point have not been as clearly delineated. Understanding of posterior column anatomy and its radiographic correlates are fundamental in the safe placement of this screw. Herein, we present technical advice for acquisition and interpretation of fluoroscopic images needed to ensure a safe trajectory and end point in retrograde percutaneous posterior column screw placement. We highlight our steps to ensure correct placement in a small series.

Percutaneous iliosacral screw fixation in unstable pelvic ring lesions: the interest of O-ARM CT-guided navigation

INTRODUCTION

The reference surgical treatment for unstable posterior pelvic fracture is percutaneous iliosacral screw fixation, isolated or in association with other techniques. As there is a risk of passage outside the bone when performing screw fixation under fluoroscopy, new image-guidance techniques have been developed: fluoronavigation, peroperative 3D navigation, CT-linked navigation, etc. Since September 2011, our department has performed iliosacral screw fixation under CT control linked to navigation so as to optimize screw positioning. This innovative technology has been used in neurosurgery in our center since 2007, for disc implants, spinal fracture, vertebral arthrodesis and intracerebral localization.

MATERIAL AND METHODS

Six patients were treated by iliosacral screw fixation for posterior pelvic ring fracture lesion. The O-ARM (Medtronic(®)) computer-assisted surgical navigation system was used, combining surgical navigation and peroperative 3D imaging. This kind of osteosynthesis is suitable for non-displaced or prereduced fracture. A radiation dose report is drawn up at end of surgery.

DISCUSSION

Postoperative course does not differ from other percutaneous osteosynthesis techniques, combing the advantages of a percutaneous approach (reduced infection and blood-loss rates, etc.) while optimizing iliosacral screw positioning. To date, no radiation overexposure has been found.

CONCLUSION

The precision and safety of iliosacral screw fixation are now unequalled, meeting the basic computer-assisted surgery principles of reduced morbidity without overexposure to ionizing radiation. Indications for computer-assisted surgery should therefore be extended to iliosacral pathologies (arthritic, tumoral and inflammatory), non-displaced acetabular fracture, etc.

Lateral sacral imaging in the morbidly obese

Obesity can complicate surgical procedures by both adding to difficulty intraoperatively and increasing postoperative complications. Intraoperative imaging can be difficult on morbidly obese patients. We have noted specifically that in morbidly obese patients where the lateral sacrum cannot be visualized on the pre-operative scout computed tomography image, the lateral sacrum will not be able to be seen on intraoperative fluoroscopy. This is an important component of preoperative planning in morbidly obese patients with pelvic ring injuries.

Sequential reduction and fixation for windswept pelvic ring injuries (LC3) corrects the deformity until healed

PURPOSE

The restoration, and fixation, of normal pelvic anatomy after a windswept type injury can be a difficult endeavor and our purpose is to describe a method to accomplish this.

METHODS

A stepwise and sequential technique was utilized to effectively reduce and stabilize this injury pattern. By first closing down the open disruption posteriorly and fixing with a partially threaded SI screw, a stable platform was created upon which to work from and subsequently distract and reduce the contralateral side via an anterior internal fixator (seven), external fixator (one), or plate (one). This was followed by a fully threaded SI screw in the compression side of the sacral fracture to hold the distraction. Nine consecutive patients with LC3 (61-B3.2) were included in the study with an average FU of 15 months.

RESULTS

The Keshishyan deformity index revealed an initial mean deformity of 0.0456 which was corrected to 0.0170 (postop) and 0.0181 at latest follow up. This entailed an average correction of 62 % at the latest follow up. The follow-up group was significantly different from pre-op (p = 0.0040), but not post-op (p = 0.6833). Furthermore, post-op was significantly different from pre-op (p = 0.0089).

CONCLUSION

This is an effective method of correcting and maintaining reduction until healing for this relatively rare and difficult-to-treat injury pattern.

Preliminary study of the feasibility and accuracy of percutaneous peri-acetabular screw insertion in a porcine model

The aim of this pilot study was to assess a new method of training for peri-acetabular screw placement under indirect vision using standard C-arm fluoroscopy using a porcine model. Two novice orthopaedic residents placed 72 screws (36 each) about the acetabula of six porcine pelves under C-arm fluoroscopic guidance. Unsatisfactory screw position was noted in 22 of 72, with five instances of screw ingress into the hip joint. All of these cases occurred in the first half of each resident's series. Screw direction and final position improved over subsequent trials. This pilot study demonstrates that surgical simulation techniques are applicable in percutaneous screw fixation. Such an approach could be useful for both residents in training and more experienced surgeons who wish to perform this procedure in cases where it is appropriate.

Posterior iliac crescent fracture-dislocation: what morphological variations are amenable to iliosacral screw fixation?

OBJECTIVES

Posterior iliac crescent fracture with associated sacroiliac joint disruption (PICFSID) is a type of traumatic posterior pelvic injury associated with instability. Posterior iliac fracture location and obliquity along with other details determine the treatment. Open reduction and internal fixation has been previously recommended for the majority of crescent fractures. Our objectives were to determine whether all crescents can be categorised according to the previously described Day crescent classification scheme, and to see which crescent types are amenable to percutaneous fixation.

PATIENTS AND METHODS

We identified 129 crescents in 128 patients during a 7-year time period. Of these, 100 patients met the inclusion criteria of at least 3 months of clinical and radiographic follow-up. There were 57 males and 43 females, with a mean age of 42 years and a mean injury severity score of 25.5. Treatment selection was based on fracture type and overall patient factors and consisted of non-operative management, pelvic external fixation, open reduction and internal fixation, and closed reduction and percutaneous iliosacral screw fixation.

RESULTS

There were 16 Type I, 47 Type II and 37 Type III crescent fractures. Twelve injuries could not be classified according to the Day scheme. Percutaneous iliosacral screw fixation was utilised in 60% of all crescents after either closed or open reduction of the PICFSID.

CONCLUSIONS

The majority of PICFSIDs are amenable to closed reduction and percutaneous iliosacral screw fixation. The Day classification for PCIFSID should be expanded to include variant injury patterns.

Management of sacral fractures associated with spinal or pelvic ring injury

BACKGROUND

The proper treatment of sacral fracture has yet to be standardized.

METHODS

Seventy-one patients with sacral fractures who were treated from December 2001 to January 2009 were evaluated. Classification was made depending on the presence of a combined injury in the spine or pelvic ring, displacement of the sacral fracture, and fracture location with surgical indications in case of a displaced fracture or neurologic injury. The surgical procedure used was either spinopelvic fixation with iliac screws or percutaneous iliosacral screw fixation. Fracture causes, treatments, classifications, the availability of the radiologic bony union and its application period, and clinical results using the Oswestry Disability Index were evaluated.

RESULTS

There were 7 patients with isolated sacral fractures, 3 patients with sacral fractures that were combined with spinal injuries, 34 patients with sacral fractures with pelvic ring injuries, and 27 cases with both spinal and pelvic ring injuries. Among these, 11 patients also showed a neurologic deficit. Of the 26 patients who were indicated for surgical treatment, 23 achieved a bony union showing favorable clinical results; however, of the three patients who were not able to undergo operation, two showed a nonunion with bad clinical results including neurologic symptoms.

CONCLUSION

Sacral fracture often accompanies spinal or pelvic ring injuries. Depending on the presence of spinopelvic dissociation, spinopelvic fixation is recommended for cases with dissociation, and percutaneous iliosacral screw fixation is recommended for cases without dissociation.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Personalized image-based templates for iliosacral screw insertions: a pilot study

BACKGROUND

Stabilization of rare unstable pelvic fractures in the case of sacral fractures and iliosacral joint dislocations can be tricky. 3D reconstruction and reverse engineering templates may be used to increase the accuracy of screw placement.

METHODS

Computed tomography (CT) images were used to design the template for 16 consecutive patients with unstable pelvic ring fractures, which were used to guide the screw placement. Another 10 patients received screw placement under conventional fluoroscopy. The screw position, radiation exposure, and surgery time were compared between the two groups.

RESULTS

Personalized image-based templates had better correct screw positions (P < 0.05), reduced radiation exposure (P < 0.01), and shorter surgery time (P < 0.05) compared with the conventional group.

CONCLUSIONS

Personalized image-based templates for iliosacral screw insertions can increase the sacral lag screw placement accuracy, reduce radiation exposure, and shorten surgery time compared with traditional fluoroscopic methods.

Surgical technique: a percutaneous method of subcutaneous fixation for the anterior pelvic ring: the pelvic bridge

BACKGROUND

Management of pelvic ring injuries using minimally invasive techniques may be desirable if reduction and stability can be achieved. We present a new technique, the anterior pelvic bridge, which is a percutaneous method of fixing the anterior pelvis through limited incisions over the iliac crest(s) and pubic symphysis.

DESCRIPTION OF TECHNIQUE

An incision is made over each anterior iliac crest and a 6- to 8-cm incision is centered over the symphysis. Either a locking reconstruction plate or a spinal rod is placed through a subcutaneous tunnel overlying the external oblique fascia in the subcutaneous tissue, and fixation into the iliac crest and pubis is achieved to effect stability.

METHODS

A randomized controlled trial comparing anterior pelvic external fixation (APEF) versus anterior pelvic internal fixation (APIF) for unstable pelvic ring injuries was begun in October 2010. Patients with unstable pelvic ring injuries were enrolled and followed with respect to fracture reduction, surgical pain, complications, and functional outcome scores.

RESULTS

As of January 2012, 23 patients met inclusion; however, 12 patients refused participation because of the possibility of external fixation, leaving 11 patients (four male, seven female) enrolled. At 6-month followup, there was a single pin tract infection in the APEF cohort and no complications or pain in the APIF cohort.

CONCLUSIONS

This clinical experience lends support to the use of a new minimally invasive technique to stabilize the anterior pelvis, particularly given the resistance on the part of patients to consider external fixation.

LEVEL OF EVIDENCE

Level II, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

A new classification for complex lumbosacral injuries

BACKGROUND CONTEXT

The optimal classification and treatment algorithm for complex lumbosacral injuries, in particular high-energy sacral fractures and lumbosacral dissociation (LSD) injuries, remains controversial. Currently used classification systems are largely descriptive, lacking validity, reproducibility, treatment considerations, and prognostic information.

PURPOSE

We set out to develop a comprehensive, yet practical, classification system for complex lumbosacral injuries that assists in clinical decision making.

STUDY DESIGN

We developed a new classification system for complex lumbosacral injuries derived through literature review, expert opinion, and our clinical experience treating combat casualties over the past 10 years. We have seen an increased incidence of complex sacral fractures and LSD injuries after high-energy blast trauma, motor vehicle collisions, and aircraft crashes.

METHODS

We performed an extensive literature review and discussed the proposed classification with spinal trauma surgeons from a variety of institutions familiar with the treatment of complex high-energy sacral fractures and LSD injuries. We identified the significant clinical and radiographic variables encountered in the decision-making process for the treatment of complex lumbosacral injuries. Existing classification systems were reviewed in light of these essential characteristics, and their limitations were defined and addressed with the new system.

RESULTS

A new classification system called lumbosacral injury classification system (LSICS) was devised based on three injury characteristics: injury morphology, posterior ligamentous complex integrity, and neurologic status. A composite injury severity score was calculated by summing a weighted score from each category, allowing patients to be stratified into surgical and nonsurgical treatment groups based on threshold values. Modifiers to determining appropriate selection for operative treatment include systemic injury load and physiological status of the polytraumatized patient, soft-tissue status, and expected time to mobility. Finally, an algorithm was developed to determine the optimum operative technique based on the previously outlined injury characteristics.

CONCLUSIONS

The LSICS provides a comprehensive and practical approach for evaluating injury severity and guiding clinical decision making. This system provides common language for surgeons to communicate various injury patterns and formulate treatment modalities. Further studies are necessary to determine the reliability and validity of this new classification system.

Percutaneous fixation of acetabular fractures: computer-assisted determination of safe zones, angles and lengths for screw insertion

INTRODUCTION

Percutaneous retrograde screw fixation for acetabular fractures is a demanding procedure due to the complex anatomy of the pelvis and the varying narrow safe bony corridors. Limited information is available on optimal screw placement and the geometry of safe zones for screw insertion in the pelvis.

METHODS

Three-dimensional reconstructions of 50 consecutive CT scans of polytrauma patients (35 males, 15 females) were used to introduce three virtual CAD bolts (representing screws) into the anterior column (superior ramus of the pubic bone), posterior column (the ischial bone) and the supraacetabular region, as performed during percutaneous screw fixation. The three-dimensional (3D) position of these screws was evaluated with a computer software (MIMICS) after virtual optimal insertion. The 3D position, the narrowest zone and the distance to the hip joint of the two columns and the supraacetabular region were defined.

RESULTS

The mean maximal screw length for the three virtual screws measured between 107.4 and 148 ± 18.7 mm. The narrowest zone of the pelvic bone (superior pubic ramus) had a width of 9.2 ± 2.4 mm. The average distances between the bolts and the hip joint were 3.9 and 19.4 ± 7.4 mm. For the anterior column (superior pubic ramus) screw, the mean lateral angle to the sagittal midline plane was 39.0 ± 3.2° and the mean posterior angle to the transversal midline plane was 15.1 ± 4.0°. The mean supraacetabular screw angles measured 22.4 ± 3.4° (medial), 35.3 ± 4.6° (cranial) and the mean angles for the ischial screw were 12.0 ± 5.4° (posterior) and 18.4 ± 4.0° (lateral).

CONCLUSIONS

The zones for safe screw positioning are very narrow, making percutaneous screw fixation of the acetabulum a challenging procedure. The predefined angles for the most frequently positioned percutaneous screws may aid in preoperative planning, decrease operative and radiation times and help to increase safe insertion of screws.

Oblique distraction external pelvic fixation

Simple anterior pelvic external fixation is a safe and effective strategy for reduction of pelvic ring deformity as well as the provisional or definitive stabilization of selected patterns of pelvic ring disruption. A two-pin oblique anterior pelvic deformity correction frame is a unique frame configuration designed to reduce and stabilize lateral compression pelvic ring disruptions associated with flexion/internal rotation hemipelvic deformities. In a small case series, we demonstrate that the oblique distraction external fixation frame alone or in combination with internal fixation is a simple and safe strategy for reduction and stabilization of unstable multiplanar hemipelvic deformities associated with partial posterior ring stability.

Percutaneous limited internal fixation combined with external fixation to treat open pelvic fractures concomitant with perineal lacerations

External fixation combined with colostomy is a traditional management of the pelvic fractures associated with perineal lacerations. However, malunion and dysfunction caused by malreduction and loss of reduction are common. One-stage definitive fixation without soft tissue harassment is requisite for the treatment. The purpose of this study was to assess the outcome of 1-stage definitive fixation by combining percutaneous limited internal fixation and external fixation in the treatment of pelvic fractures with perineal lacerations. Eighteen adults with high-energy unstable pelvic ring fractures associated with perineal lacerations were admitted between June 2003 and December 2010. Mean follow-up was 28 months. After wound closure and colostomy, 10 patients received external fixation and percutaneous screw fixation, and 8 patients underwent external fixation. Demographics, wound and fracture classification, and Injury Severity Score were comparable between the groups (P>.05). Initial reduction quality was comparable between the groups (P=.14), but the loss of reduction during follow-up was more significant in the external fixation group (P=.004). Combined fixation achieved better functional results than external fixation (P=.02). There were 2 cases of superficial wound infection in each group (P=1.0). By combining debridement, wound closure, colostomy, percutaneous limited internal fixation, and external fixation, we improved pelvic fracture recovery while reducing the risk of infection. One-stage definitive fixation is a better choice than external fixation in the treatment of open pelvic fracture concomitant with perineal wound.

Modified technique of percutaneous posterior columnar screw insertion and neutralization plate for complex acetabular fractures

BACKGROUND

To overcome the complexity of acetabular fractures, several techniques, such as extensive surgical exposure, transtrochanteric osteotomy, and columnar screw fixation, were reported. However, all these techniques have their disadvantages and limitations. We report the surgical results of a modified technique with posterior columnar screw insertion and neutralization plate in a single Kocher-Langenbeck approach for complex acetabular fractures.

METHODS

We identified 30 patients with 30 acetabular fractures who had been treated by this technique between 1995 and 2004. Demographic data, perioperative results, and complications were all recorded. The detail of surgical procedure was described and illustrated.

RESULTS

There were 13 men and 17 women with mean age of 36.4 years (range, 19-66 years). Mean follow-up duration was 49.2 months (range, 24-112 months). All fractures achieved union, and there was no loss reduction and fixation during the follow-up period. There were five complications during hospital stay, including superficial and deep infection and transient sciatic nerve palsy. There was no loss of reduction during follow-up period. Five patients underwent total hip arthroplasty caused by posttraumatic osteoarthritis and preexisting osteoarthritis. The mean Harris Hip Score at 24-month follow-up was 79.7 (median, 92; range, 33-99).

CONCLUSION

This study provided a modified surgical technique of percutaneous insertion of posterior columnar screw that appeared to be safe and reliably hold the column in place for healing.

Evaluation of 2D and 3D navigation for iliosacral screw fixation

PURPOSE

Image guidance is essential in some orthopedic surgical procedures, especially iliosacral screw fixation. Currently, there is no consensus regarding the best image guidance technique. An ex-vivo study was performed to compare conventional, 2-dimensional (2D), and 3D imaging techniques and determine the optimal image guidance technique for pelvic surgery.

METHODS

Plastic (n = 9) and donated cadaver pelvises (n = 8) were evaluated in the laboratory. The pelvises were positioned on radiolucent operation tables in a prone position. Transiliosacral screws were inserted without or with 2D- and 3D-navigational support. A digital mobile X-ray unit with flat-panel fluoroscopy and navigation software was used to measure precision, radiation exposure, and time requirements.

RESULTS

2D-navigation resulted in 40% incorrect screw positioning for the cadavers, 6% for the plastic phantoms, and 21% overall. The highest accuracy was accomplished with 3D-navigation (plastic: 100%; cadavers: 83%; p < 0.05). The dose-area product showed that both 2D- and 3D-navigation required increased exposure compared to the conventional technique (p < 0.01). For both plastic and cadaver specimens, navigated techniques required significantly longer times for screw insertion than the conventional technique (p < 0.01).

CONCLUSION

3D image guidance for transiliosacral screw fixation enabled more accurate screw placement in S1 and S2 vertebrae. However, radiation exposure in 3D-navigation was excessive; thus, we recommend avoiding 3D-navigation in young patients. A primary advantage of 3D-navigation was that the operating team could leave the room during the scan; thus, it reduced their radiation exposure. Moreover, the time required for screw insertion with 3D-navigation was similar to that required in the conventional technique; thus, 3D-navigation is recommended for older patients.

Management outcomes in pubic diastasis: our experience with 19 patients

Background

Pubic diastasis, a result of high energy antero-posterior compression (APC) injury, has been managed based on the Young and Burguess classification system. The mode of fixation in APC II injury has, however, been a subject of controversy and some authors have proposed a need to address the issue of partial breach of the posterior pelvic ring elements in these injuries.

Methods

The study included a total of 19 patients with pubic diastasis managed by us from May 2006 to December 2007. There was a single patient with type I APC injury who treated conservatively. Type II APC injuries (13 patients) were treated surgically with symphyseal plating using single anterior/superior plates or double perpendicularly placed plates. Type III injuries (5 patients) in addition underwent posterior fixation using plates or percutaneous sacro-iliac screws. The outcome was assessed clinically (Majeed score) and radiologically.

Results

The mean follow-up was for 2.9 years (6 months to 4.5 years). Among the 13 patients with APC II injuries, the clinical scores were excellent in one (7.6%), good in 6 (46.15%), fair in 4 (30.76%) and poor in 2 (15.38%). Radiological scores were excellent in 2 (15.38%), good in 8 (61.53%), fair in 2 (15.38%) and poor in one patient (7.6%). Among the 5 patients with APC III injuries, there were 2 patients each with good (50%) and fair (50%) clinical scores while one patient was lost on long term follow up. The radiological outcomes were also similar in these. Complications included implant failure in 3 patients, postoperative infection in 2 patients, deep venous thrombosis in one patient and bladder herniation in one of the patients with implant failure.

Conclusions

There is no observed dissimilarity in outcomes between isolated anterior and combined symphyseal (perpendicular) plating techniques in APC II injuries. Single anterior symphyseal plating along with posterior stabilisation provides a stable fixation in type III APC injuries. Limited dissection ensuring adequate intactness of rectus sheath is important to avoid long term post-operative complications.

Minimally invasive reduction of vertically displaced sacral fracture without use of traction table

Background

Treatment of vertically displaced sacral fracture can be difficult even for the expert traumatologist. Traditional reduction methods can show some limitations; we suggest a minimally invasive technique, which could be effective, tissue sparing and economic in terms of equipment needed.

Materials and methods

Our retrospective study included 11 patients with average age of 40.2 years (range 24–59 years), with type C pelvic ring disruption with monolateral sacral fracture (C1.3), who underwent surgical treatment from April 2007 to March 2008 using the minimally invasive technique. Radiographic examination, using Matta’s criteria, was carried out pre-operatively, post-operatively and at least at 1 year after surgery. All patients were functionally evaluated using Majeed’s grading scale with mean follow-up time of 18.9 months (range 14–25 months).

Results

Pre-operative displacements averaged 10.8 mm (range 7–21 mm); post-operative displacements averaged 5.4 mm (range 3–12 mm), with excellent or good reduction in 91% of cases. No major complications occurred. On functional evaluation, 82% of patients obtained good or excellent results.

Conclusion

The minimally invasive reduction technique, requiring a limited surgical approach and a standard radiolucent table, is in our experience a satisfactory procedure for management of monolateral vertically displaced sacral fracture.

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.

Percutaneous repair of a nonunion pubic ramus fracture using a metallic stent scaffold and cement osteoplasty

This report describes a case of repair of a nonunion pubic ramus fracture with intramedullary placement of a self-expanding nitinol stent across a fracture gap to provide a permeable scaffold for polymethylmethacrylate (PMMA) cement to track across the fracture gap and to restrict leakage into surrounding soft tissues. The patient presented with an 8-month history of pelvic pain and debility. His pain remains resolved after 14 months. Percutaneous repair of nonunion pubic rami fractures using a bridging metallic stent in combination with PMMA bone cement may be an effective treatment for these fractures.

Improving the accuracy of acetabular component orientation: avoiding malposition

Improper acetabular component orientation negatively affects the outcome of total hip arthroplasty through increasing dislocation rates, component impingement, bearing surface wear, and the number of revision surgeries. Leg length, hip biomechanics, pelvic osteolysis, and acetabular component migration are also affected by malposition. With conventional techniques, numerous variables, such as patient size, deformity and/or position, and decreased visualization, contribute to inter- and intrasurgeon acetabular component variability during surgery regardless of surgeon experience and practice volume. New acetabular component implantation techniques, such as patient-specific morphology, that incorporate anatomic landmarks may provide more accurate and individualized target zones. These techniques, coupled with the use of quantitative technology such as computer-aided navigation, may improve the precision of acetabular component placement.

A novel way to prevent lost scalpel blades during percutaneous placement of iliosacral screws

Percutaneously placed implants and reduction tools are now commonplace in orthopaedic traumatology. Significant strides toward reducing fractures and maintaining that reduction without additional harm to the soft tissue envelope have been realized. The majority of these percutaneous techniques begin with a simple "stab" incision through the skin into the deeper tissue planes beneath. With withdrawal of the scalpel, there is a possibility of dissociation of the blade relative to its handle. We describe a simple and cost-effective technique to completely eliminate this possibility.

Accuracy of minimally invasive navigated acetabular and iliosacral fracture stabilization using a targeting and noninvasive registration device

BACKGROUND

To assess the feasibility and accuracy of guide pin (GP) placement using a combined noninvasive patient immobilization and stereotactic targeting system in computer-assisted percutaneous pelvic fracture stabilization.

METHODS

A total of 12 patients with negligible dislocated unstable pelvic fractures were enrolled in this study, performed between February 2002 and October 2005. Our original plans included 13 GP placements in the iliosacral area (SF) and 8 in the acetabular (AF) area. Patients were bedded on a noninvasive dual-vacuum immobilization device. Interventions were planned on a navigation system using intraoperatively acquired CT data. Radiodense markers glued to the skin and the immobilization device provided synchronization between virtual data set and real anatomical situation. A stereotactic targeting device was used for stabilization of GP tracking. GP positions were verified intraoperatively by CT, followed by fracture stabilization with cannulated screws.

RESULTS

Mean GP placement accuracy according to plan: (1) SF-cohort: 2.8 mm (SD 2.0 mm, range 0.5-9.0 mm) at the bony entry point and 3.8 mm (SD 2.3 mm, range 0.6-9.5 mm) at the target point. (2) AF-cohort: 3.0 mm (SD 0.9 mm, range 1.6-4.9 mm) at the bony entry point and 3.9 mm (SD 1.9 mm, range 1.6-7.5 mm) at the target point. GP placement succeeded optimally in 11 out of 13 cases in the SF-cohort, and 6 out of 8 cases in the AF-cohort. The individual average dose-length product (DLP) per successful finished procedure was 1,576 mGy x cm (SD 812 mGy x cm, range 561-2,739 mGy x cm).

CONCLUSION

Our findings substantiate application of the noninvasive patient immobilization and stereotactic targeting system as effective in computer-assited percutaneous stabilization of sacral bone fractures/SI joint disruptions and coronally oriented acetabular dome fractures. We recommend according to the ALARA (as low as reasonable achievable) principle: first, the kV and mAs values have to be reduced. Second, the scanned volume has to be strictly limited to the area of interest. Third, the number of control CTs have to be minimized. Also, the IsoC might be a better choice for implant tracking below 12 cm to reduce the radiation dose to the minimum. We believe that for all high-precise GP placements in the acetabular column area, further improvements in GP guidance (inhibiting pin tip slipping and detecting intraosseous GP deflection) are necessary.

Computer Assisted Pelvic Surgery: Registration Based on a Modified External Fixator

A fundamental step in Computer Assisted Surgery (CAS) is the registration, when the preoperative virtual data and the corresponding operative anatomy of the region of interest are merged. To provide exact landmarks for anatomical registration, a tubular external fixator was modified. Two intact pelvic bones (one artificial foam pelvis and one cadaver specimen) were used for the experimental setup. Registration was carried out using a standardized protocol for anatomy-based registration in the control group; anatomical registration was achieved using a modified external fixator in the study group. This external fixator had titanium fiducials wedged into the fixator carbon tubes serving as landmarks for paired-point registration. The tubes were used for surface registration. The standard anterior pelvis fixator assembly was augmented with additional bilateral tubes oriented towards the posterior, enabling registration of the sacroiliac areas. The accuracy of registration was checked by "reversed verification", where the examiner used only the screen display to control the virtual position of the pointer tip in relation to selected landmarks. By virtual matching, the real distance was measured with a digital caliper. We defined the verification as "accurate" when the residual distance was less than 1 mm; "acceptable" when it was between 1 mm and 2 mm; and "insufficient" when it exceeded 2 mm. The paired T-test with significance levels of p < 0.05 was used for statistical analysis. The anatomical registration based on the external fixator landmarks was statistically as accurate as that obtained using anatomical landmarks on the pelvic bone. This study concludes that the external fixator, a conventional tool in the management of acute traumatic pelvic instability, can also be useful for landmark registration in CAS.

Accuracy of Computer Assisted Percutaneous Placement of Hiosacral Screws: A Cadaveric Study

OBJECTIVE

To determine the accuracy of computer-assisted fluoronavigation for percutaneous iliosacral screw placement.

MATERIALS AND METHODS

A fluoronavigation system (Stryker Navigation System, Stryker Leibinger, Kalamazoo, MI) was used to guide the placement of four iliosacral screws into the S-1 bodies of each of five cadaveric pelvic specimens with intact soft tissues. Accuracy of screw placement was verified by radiographs, CT scans, and direct dissection.

RESULTS

All 20 screws were placed accurately without complications. Nineteen screws were completely contained within the osseous "safe zone." On direct dissection, one screw was noted to have penetrated the S-1 foramina by 3 mm without impingement on the nerve root. This was not detected on radiograph or CT scan.

CONCLUSION

The results of this study support the safety and accuracy of computer-assisted fluoronavigation for iliosacral screw placement. The advantages include decreased fluoroscopic time, real-time simultaneous visualization of all three views (inlet, outlet, and lateral), and increased accuracy of placement. Clinical study is warranted.

Pelvic ring fractures internal fixation: iliosacral screws versus sacroiliac hinge fixation

INTRODUCTION

Pelvic ring fractures are severe injuries whose functional results depend on the quality of reduction. Numerous internal fixation alternatives have been described, but the biomechanical studies comparing them remain rare.

HYPOTHESIS

This study compared the biomechanical behavior of iliosacral screws (ISS) with sacroiliac hinge type fixation (SIF) following unstable pelvic ring fractures fixation.

MATERIALS AND METHODS

A lesion simulating sacroiliac disruption and pubic disruption was created on 14 cadaver pelves. After randomization, the fractures were internally fixed using an anterior plate associated with either an ISS or an SIF. The specimens were then submitted to forces applied vertically at the coxofemoral joints. Relative movements in vertical translation and in rotation between the iliac wing and the sacrum, as well as the stiffness and the forces at failure of the assemblies were measured and compared.

RESULTS

The mean age of the bodies was 66 years (+/-8). No significant difference was demonstrated between the groups in terms of residual motion and stiffness in both vertical and rotational displacement. The results showed a slight residual mobility in rotation of the hemipelvis. The SIFs presented greater, although non significant resistance to failure. No fixation, however, restituted stiffness comparable to a healthy pelvis.

DISCUSSION

The results of this study show that a Tile C.1.2-type injury to the pelvic ring can be treated as effectively with ISS or SIF when combined anterior and posterior fixations are performed. SIF therefore seems reliable and its continued use is justified. The long-term clinical outcomes should nevertheless be evaluated, notably on the younger population, more often affected by this type of injury.

U-shaped sacral fractures: surgical treatment and quality of life

BACKGROUND

U-shaped sacral fractures are rare and highly unstable pelvic ring fractures. They are not recognised in the standard classification systems of these fractures. The fracture pattern is associated with significant neurological injury and can lead to progressive deformity and chronic pain if not diagnosed and treated properly. In recent years a variety of surgical strategies have been shown to facilitate early mobilisation and reduce early mortality as compared to non-operative strategies. Poor evidence, however, has hampered the development of a standard treatment algorithm. As for the long-term morbidity, the influence of operative treatment may be difficult to assess due to associated injury. However, evidence exists that there is a significant effect on the long-term morbidity.

OBJECTIVE

To assess the injury characteristics, choice of treatment and quality of life of U-shaped sacral fractures.

METHODS

Eight polytraumatised patients with U-shaped sacral fractures were identified over a 7-year period and evaluated retrospectively. They were analysed for fracture classification, associated injury, and injury severity. Clinical and Radiological results were evaluated. Neurological outcome was retrospectively classified by Gibbons' criteria. Long-term quality of life outcome was evaluated using the EuroQoL-6D questionnaire.

RESULTS

The study population consists of five women and three men; with a median age of 29 years. All patients sustained severe associated injury. The Injury Severity Score ranged from 17 to 45 (median 23). The median time between trauma and definitive internal fixation was 4 days (range, 2-22 days). Definitive fixation included either percutaneous iliosacral screws (n=2), transsacral plate osteosynthesis (n=1) or triangular osteosynthesis with (n=4) or without transsacral plating (n=1). Early postoperative mobilisation and early partial weight-bearing were encouraged when possible. Follow-up ranged from 5 to 65 months (median, 36 months). Pain, mood disorders and mobility problems mainly influenced patients' present general health status.

CONCLUSION

U-shaped sacral fractures present a rare and heterogeneous injury. Operative treatment depended mainly on fracture type, associated spinal fractures, and the surgeon's preference. Long-term quality of life is dominated by pain, mood disorders and moderate mobility problems.

Early experience with reduction of displaced disruption of the pelvic ring using a pelvic reduction frame

We describe our early operative experience with a new pelvic reduction frame and the standard of reduction of fractures of the pelvic ring which we achieved in the first 35 consecutive patients, with 34 acute fractures and one nonunion. The pre-operative and immediate post-operative radiographs were measured, using two methods, to find the maximum radiological displacement of the fracture and the quality of the reduction according to the criteria of Tornetta and Matta. There were 19 vertical shear fractures and 16 compression injuries. The mean age of the patients was 33.5 years (10 to 59) and mean delay to surgery was 4.6 days (0 to 16) in the 34 acute injuries. The mean operative time in isolated procedures was 103.4 minutes (SD 6.5). All but one patient had iliosacral screws implanted, 18 had screws in the anterior column, six had plates at the symphysis pubis and 12 had anterior external fixators. The mean maximum horizontal or vertical displacement was improved from 30.8 mm (SD 2.7) to a mean of 7.1 mm (SD 0.7). The reduction was assessed as excellent in ten patients, good in 18, and fair in the remainder. There was no significant influence on the quality of the reduction caused by obesity (p = 0.34), the type of fracture (p = 0.41) or delay to surgery (p = 0.83). The frame was shown to be effective, allowing the surgeon to obtain a satisfactory reduction and fixation of acute displaced disruptions of the pelvic ring.

The upper sacral nerve root tunnel: an anatomic and clinical study

OBJECTIVES

To radiographically demonstrate the upper sacral nerve root tunnel (USNRT) in both cadaveric specimens and a clinical cohort and to quantify its clinical relevance.

SETTING

Level 1 trauma center and anatomy laboratory.

PATIENTS AND PARTICIPANTS

Eleven cadaveric pelves and 23 consecutive patients who underwent fluoroscopically assisted iliosacral screw insertions.

INTERVENTIONS

Cadaveric pelves were fluoroscopically imaged using standard pelvic inlet, outlet, and true lateral sacral views. The course of the USNRT pathway was identified. Then, these tunnels were filled completely with a semisolid radio-opaque agent. The specimens were reimaged after the contrast injection. Clinically, 23 consecutive patients with unstable posterior pelvic ring disruptions were treated using fluoroscopically assisted percutaneous iliosacral screws based on these predictable radiographic landmarks. A total of 44 iliosacral screws were inserted.

MAIN OUTCOME MEASUREMENTS

For the cadaveric portion, the images with contrast were used to identify the USNRTs. For the clinical study, tunnel visualization was determined on all views intraoperatively. Screw placement was documented by postoperative pelvic plain radiographs and computed tomography scan.

RESULTS

In the cadaveric specimens, the contrast agent consistently demonstrated the USNRTs on all 3 pelvic radiographic views. In the clinical series, the USNRTs were well visualized on the pelvic outlet image in all 23 patients (100%). Using the inlet image, the USNRTs were visualized in only 5 of 23 patients (21%). On the true lateral sacral views, the USNRTs were seen in 21 of 23 patients (91%). Using these USNRT radiographic landmarks, no iliosacral screw was extraosseous.

CONCLUSIONS

The USNRTs have a consistent radiographic appearance that is best seen on the pelvic outlet and true lateral sacral views, but their course is best understood when seen on all 3 views. Awareness and understanding of the USNRT, its course, and its radiographic landmarks allow the surgeon to avoid tunnel intrusion by an iliosacral screw.