骶髂螺钉的正确打法

Injury,Int.J.Care Injured(2004)35,S-A46—S-A560020–1383/$—see front matterß2004Published by Elsevier Ltd. doi:10.1016/j.injury.2004.05.010For musculoskeletal tumor resections, it is rather difficult to define the exact resection line because normal and cancerous bone can hardly be differenti-ated in most cases. With exact resection, however, the preservation of osseous structures, eg, parts of the sacrum, is possible as well as preservation of nerve roots.Navigation procedures based on CT data are well proven in spinal surgery. With reduced radiation exposure, the precision can be enhanced [3]. In our own clinical practice, CT-based navigation is part of the clinical routine for dorsal spine instrumenta-tion. Between May and December 2000, 124 out of 126 pedicle screws inserted in the thoracic spine were placed correctly [13]. Based on these good experiences, CT-based navigation was used in pelvic surgery as well.Fluoroscopy-based n avigation o ffers t he a dvantage that the fluoroscope is already present in the operat-ing room (OR) and current images can be acquired whenever needed. Up to four C-arm projections can be displayed simultaneously on the navigation screen. Therefore, no intraoperative re-orientation of the fluoroscope is needed. After experimental definition of adequate fluoroscopy projections for five typical pelvic screws [12], fluoroscopy-based navigation was used in the clinical set-up. Modality-based navigation uses a specially de-signed and equipped CT-suite as an OR. Navigation is performed on the basis of the CT data with the possibility of immediate CT-control of the reduction and the navigation procedure as well.The clinical experiences with the different naviga-tion techniques in pelvic surgery are described with a particular focus on indications, operative technique, and limitations.Methods an d r e l e van t in d ica t i o n s Between June 1st, 2000 and December 31st, 2002 there were 41 percutaneous screw fixations per-formed with either CT- or fluoroscopy-based navi-gation.Ac et abular frac t ur e P e lvic ringinjurySIar th r os i snCT-ba sednaviga t i o n3115Flu o r os c o py-ba sed naviga t i o n820836 n1121941 T able 1: Indications for navigated screw fixations.Three musculoskeletal tumors were resected us-ing CT-based navigation. There were two chordomas of the sacrum and one Ewing sarcoma of the iliac wing.CT-ba sed naviga t i o nFor CT-based navigation, the CT-based spine module of Medivision® can be used. CT data with at least 2mm slices was transferred to the workstation. Within the 3-D reconstruction, the reference points for the paired point matching have to be defined and the preoperative planning performed. For per-cutaneous procedures, we recommend positioning the reference points along the iliac crest, which is easily accessed with small skin incisions. In addition to the palpable anterior superior iliac spine, ad-ditional points in a defined distance along the iliac crest are recommended. Marker screws can be used but have the disadvantage of an additional operative procedure before the CT. For tumor resections, the reference points were defined within the operative area. For surface matching, 15–20 points were ac-quired with the pointer. These points were located in the area of the reference points or in the operative area as well. After successful matching and verifi-cation, the navigated procedure was started. The fluoroscope was left in the OR-setup for the whole procedure to enable intraoperative control of the position of the guided instruments.Flu o r os c o py-ba sed naviga t i o nA conventional fluoroscope was used (Ziehm®) and the C-arm navigation module was from Medivision®. Optoelectronic markers were mounted onto the instruments, the dynamic reference base, and the fluoroscope. An infrared camera assessed the posi-tion in space. Up to four fluoroscopy projections can be displayed simultaneously on the navigation screen. The direction and length of the navigated drill or drill sleeve can be followed on the screen and thus be controlled in all four projections without additional imaging.S et-up(Fig.1)All navigated procedures need to be planned in advance regarding the set-up in the OR. For navi-gated pelvic surgery, the optoelectronic camera is positioned at the feet of the patient with about 2 m distance to the dynamic reference base, mostly mounted in the iliac crest of the side to be operatedon. The surgeon is on the operative side, with the fluoroscopy and navigation monitor positioned on the opposite side.Op e ra t iv e te c h niqu e f o r s cr e w fixa t i o n sFor screw fixations, 7.3 mm cannulated screws were used with a 2.8 mm guidewire. As preclinical tests showed deviations of the guidewire from the planned course in the bone, the technique for navigated cannulated screws was changed. After successful matching or acquisition of the appropriate fluor-oscopy projections, the correct skin incision point is defined with the navigated pointer . After skin incision and blunt dissection, the osseous entrance point was marked and the navigated drilling was performed with a specially reinforced drill and the referenced machine. In case of sacroiliac screws (SI), the drilling was just executed across the SI joint. After inserting the guidewire into the drill and fluoroscopic control of the position, the cannulated screw was inserted.Within the series, we noticed that movements with the navigated machine led to misleading changes in the screen display for navigation even though direction of the drill was unchanged (Fig. 2a). Therefore, a referenced drill sleeve was developed (Fig. 2b). This drill sleeve was inserted with a blunt trocar and had several sharp tips at the end for se-cure anchoring in the bone. Other than that point, the technique remained the same.T o assess the precision of the procedures, all screws were controlled with CT . For fluoroscopy-based navigation, fluoroscopy images, navigation screens, and postoperative x-rays were also com-pared.Fig. 1: OR–setup for navigation.Fig. 2: Technique a) M ovement of the referenced machine without chang-ing the effective direction of the drill, but with a clear change on the navigation screen. b) N ew developed navigated drill sleeve for percutaneous screw fixations.Fig 3: Modality-based navigation. 51-year-old patient, roofer, fell off a roof and was treated conservatively over several weeks for a sac-ral fracture. Fol-lowing persistent severe pain, decision to carry out a CT-control-led, navigated osteosynthesis. As a result the patient became pain-free and fit for work.4a) Pelvic x-ray after SI fixation right, matching within the surgical approach on the left side. 4b) Defining of the skin incision point according to the preoperative planning.4c) Intraoperative navigation with guidance and realtime modusFig. 4 a—e: CT-based navigation for transiliosacral screw.For painful bilateral SI arthrosis probatory SI screw fixation right was already performed with pain relief indication for definitive SI stabilisation bilateral. Inserting of the left SI screw with CT based navigation.d) After drilling with the reinforced navigation drill, inserting of the guide wire and the cannulated screwe) Postoperative x-ray after bilateral SI stabilisation , postoperative CT with correct position of the SI screw left,identical to the planning.Within the tumor cases, the resection lines were defined with navigated chisels as planned preopera-tively after successful matching and verification. Postoperatively , the resection areas were examined histologically .Mod ali t y-ba sed naviga t i o n (Fig. 3)The method of modality-based navigation is differ-ent to the above-mentioned techniques. Surgery is performed within a specially equipped CT-suite or in an OR with integrated CT . The patient is positioned on the CT table and the instruments are navigatedon the basis of the CT data, with the opportunity for immediate CT control of reduction maneuvers as well as all operative steps (Fig. 3).R es ul tsCT-ba sed naviga t i o n (Fig. 4, 5)With CT-based navigation, two percutaneous screw fixations of minimally displaced acetabular fractures were performed. One case was an anterior column fracture, the other a transverse fracture. For the an-a) Pelvic x-ray and CT after neoadjuvant treatment (Euro Ewing Schema).b) MRI and intraoperative situsFig. 5 a—d: 21-year-old patient with Ewing sarcoma of the right iliac wing.terior column fracture, one screw was inserted, and for the transverse fracture, two screws. The match-ing procedure was successful in both cases with two small incisions at the iliac crest. During the verifica-tion procedure we figured out that navigation is only possible with all points of the surface matching on the side to be operated on. With surface points on the contralateral side, the navigation display did not correspond with intraoperative fluoroscopy control, despite good matching results. The position of all the navigated screws was correct and perfectly cor-responded with the preoperative planning.In two cases, percutaneous SI screw fixations were performedusingCT-basednavigation. The indica-tions were one iliosacral dislocation fracture and one iliosacral arthrosis. In these cases, the matching5c) Defining of the resection lines with CT-based navigation.5d) Pelvic resection type IV Eneking and Dunham, postop-erative x-ray after stabilisation with two fibula grafts and distractionsspondylodesis.was also successful, with the first trial using two additional skin incisions at the iliac crest. The place-ment of the screws was identical to the preoperative planning (Fig. 4e).For tumor resections, paired point andsurfacematchingoccurredwithout any problems. The resec-tion line was exactly defined as planned preopera-tively . The histological examination revealed tumorfree resection lines in all cases. In the patient with the Ewing sarcoma in the iliac wing, the continuity of the pelvic ring was reconstructed with two fibula grafts.Flu o r os c o py-ba sed naviga t i o n(Fig.6)With fluoroscopy-based navigation, eight percuta-neous screw fixations were performed for acetabular fractures, and 28 transiliosacral screws were placed with 27 in S1 and one in S2.In one case of an iliosacral dislocation fracture, malreduction of the posterior pelvic ring was only noticed in the postoperative x-ray. Because of the re-duced image quality due to the navigation markers, it was not recognized intraoperatively. The revision surgery was then performed in the conventional way. In one patient with bilateral transforaminal sacral fractures and bilateral SI screws, the position of the screws was stated correctly in the postoperative x-rays (inlet, outlet view), whereas the CT showed an anterior cortex perforation of the sacrum on one side. With otherwise good reduction and because of the absence of neurological symptoms the screw was left in place.Except for this one misplacement, 35 of the 36 screws placed with fluoroscopy-based navigation were positioned correctly in x-ray and CT control. The average fluoroscopy time per procedure was 0.5 min.Di s cu ss i o nThe most frequent application of percutaneous screws in the pelvis are transiliosacral screws for minimally displaced sacral fractures or SI disrup-a) Pelvic x-ray and CT.b) Acquisition of the fluoroscopyprojections.c) I ntraoperative navigation screen forSI screw fixation right, postopera-tive x-ray.Fig. 6 a—c: Unstable pelvic injury with sacral fracture (C1.3).tions, which can be reduced by closed maneuvers [1, 8—10]. However, percutaneous screws are also used for acetabular fractures with appropriate frac-ture configuration and possible closed reduction [2, 7, 11]. For minimally displaced acetabular fractures, the aim of the percutaneous stabilization is early mobilization. As percutaneous pelvic stabilization is a technically ambitious procedure because of the pelvic geometry, average fluoroscopy times between 1.4 and 4.4 min per procedure are reported [8, 9, 11].CT-based navigation allows a procedure with high precision, especially in cases with no or minimally displaced fractures [1, 2, 6]. The matching proce-dure can be difficult because the osseous pelvis is surrounded by spacious soft tissues. Either fiducials can be used or it is necessary to define points along the iliac crest that are easily accessible through small skin incisions. For reduction maneuvers, a new CT dataset is necessary after each manipulation. Therefore, a CT needs to be available in the OR, resulting in concomitant logistical problems.In tumor surgery, a differentiation of intact or infil-trated bony surface can be difficult but is necessary to define the resection line. CT-based navigation can use the information from the CT intraoperatively. With additional visualization, the resection line can be planned exactly and executed safely. The match-ing procedure is easy to perform within the operative approach. In our three cases, the resection was per-formed according to the preoperative planning with histologically safe resection areas. With the fusion of additional imaging modalities like MRI, navigation procedures will be of increasing benefit even for soft tissue tumor surgery, especially when intraoperative referencing with ultrasound is possible.For fluoroscopy-based navigation, good quality of the defined fluoroscopy projections is mandatory for safe and precise screw positioning. In cases of insufficient image quality, the navigated procedure may not be performed. With good image quality, however, the pelvic screws, mainly SI screws, can be inserted securely and precisely with an average fluoroscopy time of 0.5 min per screw. This is a clear advantage compared to conventional procedures [8, 9]. For sacral dysplasia, which can be detected in CT, CT-based navigation is to be preferred.For both procedures, CT-based as well as fluor-oscopy-based, the fluoroscope remains in the OR throughout the procedure. The navigation system is an additional tool to enhance the precision with decreased radiation exposure. The navigation sys-tem itself cannot guarantee a 100% precision, not even with good matching values for registration. Unnoticed manipulations of the dynamic reference base, for example, can lead to a complete shift of the image. The navigation screen always displays a ‘virtual reality’, whereas the fluoroscope shows the real situation. T o avoid severe misplacements as described by other groups [3], it is therefore strongly recommended to leave the fluoroscope in the set-up and to control the operative steps in at least one projection.For percutaneous screw fixations, the described technique with the navigated drill sleeve and reinforced drill is recommended. Because of the tendency of the guidewire to bend, it is necessary to start the procedure with the cannulated drill to effectively use the advantages of the additional visualization with navigation.Overall, the results of the fluoroscopy-based navigation are very satisfying for the technically ambitious application of percutaneous pelvic screws with 35 of 36 screws placed correctly. With just 0.5 min radiation exposure, high precision of the screws was achieved. With further improvements in image quality and some technical changes, a further im-provement in precision is to be expected.The Siemens Iso C 3-D fluoroscope combines the advantages of CT- and fluoroscopy-based naviga-tion. It offers the advantage of axial cuts, 2-D and 3-D reconstructions, and enables immediate reduc-tion control. The image quality is clearly decreased compared to the CT but is sufficient to assess the reduction quality in the posterior pelvic ring and to navigate on the basis of these images. The first clini-cal cases are promising, and further clinical studies will show the potential of this new method, not only in pelvic surgery.CT ba sed Flu o r os c o pyba sedMod ali t yba sedA d van t ag es• P reoperativeplanning• A xial cuts• 3-Dreconstruction• N o matching• A ll timeupdatepossible• G oodreductioncontrolDi s a d van-t ag es• M atchingnecessary• N o updatewithout CT• N o axialcuts• L imitedimagequality• L imitationsforreductionmaneuversIn d ica t i o n s• N on-displacedfractures• D ysplasia• T umorresections• D isplacedfractures• S tandardprojections• A llfractureswith minorreductionsT able 2: Indications for navigation procedures in pelvic surgery.Modality-based navigation offers the opportu-nity for immediate CT control of all operative steps. Especially for the posterior pelvic ring, this is a clear advantage compared to the two other methods. Weknow that about 30% of all sacral fractures can only be detected in CT and only with the axial cuts and 2-D reconstructions of CT data can the reduction quality of the posterior ring be assessed adequately in all cases. Image quality is still the limiting factor for fluoroscopy and the Iso C 3-D offers the ability for axial and 2-D reconstructions, but image quality is clearly decreased compared to CT.For percutaneous pelvic surgery, modality-based navigation is the best method in terms of immediate quality control. But one has to take into account that a special CT suite or an interventional OR with CT is necessary for these procedures with some associated logistical problems. Limitations regarding reduction techniques and open surgical procedures need to be dealt with as well. R e f e r e nc es1. Ebrahim NA, Coombs R, Jackson WT, et al. (1994) Percutane-ous computed tomography-guided stabilization of posterior pelvic fractures. Clin Orthop; 07: 222–228.2. 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(1995) Early resultsof percutaneous iliosacral screws placed with the patient in the supine position. J Orthop Trauma;9(3): 207–214.9. Routt ML Jr, Simonian PT (1996) Closed reduction and per-cutaneous skeletal fixation of sacral fractures. Clin Orthop;329:121–128.10. Shuler TE, Boone DC, Gruen GS, et al. (1995) Percutaneousiliosacral screw fixation; early treatment for unstable poste-rior pelvic ring disruptions. J Trauma; 38(3): 453–458.11. Starr AJ, Reinert CM, Jones AL (1998) Percutaneous fixationof the columns of the acetabulum: a new technique. J Orthop Trauma; 12(1): 51–58.12. Stöckle U, König B, Hofstetter R, et al. (2001) Bildwandler-basierte Navigation: Eine experimentelle Studie zu Becken-verschraubungen. Unfallchirurg; 104: 215–220.13. Stöckle U, König B, Kandziora F, et al. (2001) Clinical experi-ences with CT-based navigation in the thoracic spine. Comp Aid Surg; 6: 120.14. Suhm N, Jacob AL, Nolte LP, et al. (2000) Surgical navigationbased on fluoroscopy: clinical application for computer-as-sisted distal locking of intramedullary nails. Comp Aid Surg;5: 391–400.Correspondence address:Priv. Doz. Dr. Ulrich StöckleZentrum für Muskuloskeletale ChirurgieCHARITÉ — Universitätsmedizin BerlinCampus Virchow KlinikumAugustenburgerpl.113353 Berlin, Germanyphone: 030 450 52033fax: 030 450 52901email: ulrich.stoeckle@charite.de。