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CRANIOMAXILLOFACIAL TRAUMA
Q2 Q8
Q7
Influence of Mirrored Computed Tomograms on Decision-Making for Revising Surgically Treated Orbital Floor Fractures Michael Blumer, MD,* Thomas Gander, MD, DMD,y Astrid Kruse Gujer, MD, DMD,z Burkhardt Seifert, Prof Dr,x Martin R€ ucker, MD, DMD,k and Heinz-Theo L€ ubbers, MD, DMD{ Purpose:
This study evaluated whether intraoperative imaging with computer-assisted virtual reconstruction would be advantageous in reconstructions of orbital floor fractures. The surgeon’s intention to revise a reconstructed primary orbital floor fracture by evaluating a postoperative mirrored computed tomographic (CT) scan was analyzed intraoperatively before wound closure, during inpatient hospitalization, and after hospitalization. The inter-rater agreement and the match of intention to revise and actual revision were analyzed.
Materials and Methods:
Fifty-one anonymized postoperative CT scans of patients with a unilateral orbital floor fracture were mirrored using software. These computer-assisted virtual reconstructions were consecutively examined by 4 examiners. Seven of these patients underwent a revision. In the first part, the inter-rater agreements for all 3 times were analyzed. In the second part, the examiners’ intentions to revise were compared with the actual performed revisions.
Results:
The overall inter-rater agreements were 0.69 for the intraoperative phase, 0.55 for the in-hospital phase, and 0.39 for the post-hospital phase. The intraoperative inter-rater agreement for each examiner was 0.58 to 0.80. The Fleiss k value for the in-hospital and post-hospital phases was lower. The comparison of the examiners’ intention to revise and the actual revisions showed that 15 to 24 additional would have been revised. In contrast, 6 of 7 actual revisions would have been revised intraoperatively. The missed actual revision was the same case by all 4 examiners. The accordance of intention to revise with the actual revisions decreased during hospitalization and even more after hospitalization. This study showed strong agreement among examiners for revising anatomically incorrectly reduced orbital floor fractures intraoperatively by evaluating postoperative mirrored CT scans. During the in-hospital and post-hospital phases, the restraints against revision seemed to increase, thus leading to poorer inter-rater agreement. This analysis of postoperative CT scans with computer-assisted virtual reconstructions of the orbit would have led to considerably more revisions intraoperatively, but all actual revisions were detected except for 1 case. This case was the same for all 4 examiners. Operation time would have been prolonged in the additional revised cases, but a better anatomic reconstruction would have been achieved. Furthermore, the intraoperative result of the reconstruction would have been controlled instantly and corrected immediately, if needed.
*Resident, Clinic for Craniomaxillofacial Surgery, University
This study was funded in part by the Swiss Association of Dento-
Hospital, Zurich, Switzerland.
Maxillofacial Radiology (grant 14-01).
yFellow, Clinic for Craniomaxillofacial Surgery, University
Address correspondence and reprint requests to Dr L€ ubbers:
Hospital, Zurich, Switzerland.
Clinic
zFellow, Clinic for Craniomaxillofacial Surgery, University
for
Craniomaxillofacial
Surgery,
University
Hospital,
R€amistrasse 100, 8091 Z€ urich, Switzerland; e-mail: [email protected]
Hospital, Zurich, Switzerland.
Received February 23 2015
xAdjunct Professor, Department of Biostatistics, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich,
Ó 2015 American Association of Oral and Maxillofacial Surgeons
Switzerland.
0278-2391/15/00894-0
Accepted June 18 2015
kProfessor and Medical Director, Clinic for Craniomaxillofacial
http://dx.doi.org/10.1016/j.joms.2015.06.159
Surgery, University Hospital, Zurich, Switzerland. {Fellow, Clinic for Craniomaxillofacial Surgery, University Hospital, Zurich, Switzerland.
1.e1 FLA 5.2.0 DTD YJOMS56884_proof 11 July 2015 4:47 pm CE AH
57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112
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1.e2
MIRROR CT FOR SURGICAL REVISION
Conclusion:
Q3
This study showed that of 6 of 7 actual revisions, implant placement would have been revised intraoperatively by all 4 examiners, if intraoperative imaging with computer-assisted virtual reconstruction of the orbit would have been applied. Therefore, the authors suggest that intraoperative imaging with computer-assisted virtual reconstruction could be advantageous in the prevention of later revisions of orbital floor fractures. In this study, the threshold to revise implant placement intraoperatively seemed to be lower when using intraoperative imaging with virtual reconstructions, because considerably more cases would have been revised intraoperatively by the examiners. In the in-hospital and post-hospital phases, this threshold increased, suggesting the more important role of clinical findings. It is uncertain whether the actual surgeons would have revised the same cases as the examiners if they had used intraoperative imaging with virtual reconstructions for their deliberation. However, the intraoperative interrater agreement was good and cost-intensive postoperative revisions might be prevented. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1.e1-1.e9, 2015 Orbital floor fractures are common in midfacial fractures1 deriving from facial trauma. Various studies have discussed indications and timing for operative repair of orbital floor fractures because oculofacial surgery is not without risk.2 If not operated on in time and appropriately, then complications, such as enophthalmia or diplopia, can occur.3-6 New surgical and imaging techniques have improved the functional and esthetic outcomes of reconstructions,6-8 and surgical navigation has become an established technique in oral and maxillofacial surgery.9-12 Intraoperative multidetector computed tomographic (CT) and cone-beam CT (CBCT) scans to confirm ideal reconstruction have been described in the literature as effective.13-24 However, to the authors’ knowledge, no study has investigated the influence of computer-assisted virtual reconstructions of the orbit on a surgeon’s decision to revise a reconstruction of an orbital floor fracture. The aim of this study was to test whether a surgeon would revise the result of a primary orbital floor reconstruction by reviewing a mirrored postoperative CT scan at 3 particular times: 1) intraoperatively before wound closure, 2) during inpatient hospitalization, and 3) after hospitalization. The extent to which these revisions correspond to effectively revised cases is based on clinical results. This is a means to evaluate whether intraoperative imaging is advantageous.
Material and Methods Anonymized postoperative CT scans of 51 patients with a reconstructed unilateral orbital floor fracture were included in this study. Postoperative imaging was conducted from September 2009 through December 2012 in the Clinic for Craniomaxillofacial Surgery at the Universit€atsspital Zurich (Zurich, Switzerland). None of the patients underwent intraoperative imaging during the surgical procedure. Seven of the 51 patients subsequently underwent revision surgery after the surgical repair.
These postoperative CT scans were imported into Brainlab iPlan Net software (Brainlab AG, Feldkirchen, Germany) as described in a previous study.14 The autosegmentation function of the program was used on the unaffected orbit to obtain a virtual 3-dimensional (3D) template. Then, the computed 3D template was controlled and manually trimmed using the provided software tools, if necessary (Fig 1). This 3D template was mirrored and manually superimposed to the best fit onto the affected orbit using the orbital roof in the sagittal plane and the orbital rim in the coronal plane as landmarks (Fig 1). Then, these modified postoperative CT scans were saved on the clinic server as Digital Imaging and Communications in Medicine (DICOM) datasets to be analyzed by the examiners. Information about the affected side, injury pattern, and materials used for reconstruction (polydioxanone [PDS], titanium mesh, or PDS and titanium Q4 mesh) was assessed using these anonymized postoperative CT scans. Subsequently, whether a surgeon would revise the surgically repaired orbital floor fracture was analyzed using the datasets. Examiners assessed the postoperative CT scans with the mirrored, unaffected orbit as reference. Deliberate clinical symptoms were not included. Two experienced consultants (examiners 1 and 3) and 2 residents (examiners 2 and 4) analyzed the datasets and decided whether a revision was favorable. The deliberations were separated for 3 different periods: 1) when the surgeon would see the CT scan intraoperatively before closing the surgical access, 2) during inpatient hospitalization, and 3) after hospitalization. These results were analyzed for inter-rater agreement, and the examiners’ intentions to revise were compared with the actual revisions. Each measurement was analyzed for the entire study population, for cases treated with PDS, and for cases treated with titanium mesh. Statistical analyses for the patient population were performed using Excel (Microsoft Corporation,
FLA 5.2.0 DTD YJOMS56884_proof 11 July 2015 4:47 pm CE AH
Q1
169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224
1.e3
225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280
web 4C=FPO
BLUMER ET AL
FIGURE 1. The auto-segmentation function of the software was used on the unaffected orbit for a computed 3-dimensional template (green). This template was searched for possible errors and manually trimmed when needed. Then, the template was mirrored and superimposed, resulting in virtual reconstruction of the affected orbit (red). In this case, the virtual reconstruction of the fractured orbit shows the correct shape and position of the implant. Blumer et al. Mirror CT for Surgical Revision. J Oral Maxillofac Surg 2015.
Redmond, WA). The inter-rater agreement was assessed using the Fleiss k value.25 For these calculations, STATA 13.1 (StataCorp LP, College Station, TX) was used. To calculate the 95% confidence interval (CI) 5,000 bootstrap replications were applied. Agreement between examiners is usually graded according to the method of Landis and Koch26 as poor (
CRANIOMAXILLOFACIAL TRAUMA
Q2 Q8
Q7
Influence of Mirrored Computed Tomograms on Decision-Making for Revising Surgically Treated Orbital Floor Fractures Michael Blumer, MD,* Thomas Gander, MD, DMD,y Astrid Kruse Gujer, MD, DMD,z Burkhardt Seifert, Prof Dr,x Martin R€ ucker, MD, DMD,k and Heinz-Theo L€ ubbers, MD, DMD{ Purpose:
This study evaluated whether intraoperative imaging with computer-assisted virtual reconstruction would be advantageous in reconstructions of orbital floor fractures. The surgeon’s intention to revise a reconstructed primary orbital floor fracture by evaluating a postoperative mirrored computed tomographic (CT) scan was analyzed intraoperatively before wound closure, during inpatient hospitalization, and after hospitalization. The inter-rater agreement and the match of intention to revise and actual revision were analyzed.
Materials and Methods:
Fifty-one anonymized postoperative CT scans of patients with a unilateral orbital floor fracture were mirrored using software. These computer-assisted virtual reconstructions were consecutively examined by 4 examiners. Seven of these patients underwent a revision. In the first part, the inter-rater agreements for all 3 times were analyzed. In the second part, the examiners’ intentions to revise were compared with the actual performed revisions.
Results:
The overall inter-rater agreements were 0.69 for the intraoperative phase, 0.55 for the in-hospital phase, and 0.39 for the post-hospital phase. The intraoperative inter-rater agreement for each examiner was 0.58 to 0.80. The Fleiss k value for the in-hospital and post-hospital phases was lower. The comparison of the examiners’ intention to revise and the actual revisions showed that 15 to 24 additional would have been revised. In contrast, 6 of 7 actual revisions would have been revised intraoperatively. The missed actual revision was the same case by all 4 examiners. The accordance of intention to revise with the actual revisions decreased during hospitalization and even more after hospitalization. This study showed strong agreement among examiners for revising anatomically incorrectly reduced orbital floor fractures intraoperatively by evaluating postoperative mirrored CT scans. During the in-hospital and post-hospital phases, the restraints against revision seemed to increase, thus leading to poorer inter-rater agreement. This analysis of postoperative CT scans with computer-assisted virtual reconstructions of the orbit would have led to considerably more revisions intraoperatively, but all actual revisions were detected except for 1 case. This case was the same for all 4 examiners. Operation time would have been prolonged in the additional revised cases, but a better anatomic reconstruction would have been achieved. Furthermore, the intraoperative result of the reconstruction would have been controlled instantly and corrected immediately, if needed.
*Resident, Clinic for Craniomaxillofacial Surgery, University
This study was funded in part by the Swiss Association of Dento-
Hospital, Zurich, Switzerland.
Maxillofacial Radiology (grant 14-01).
yFellow, Clinic for Craniomaxillofacial Surgery, University
Address correspondence and reprint requests to Dr L€ ubbers:
Hospital, Zurich, Switzerland.
Clinic
zFellow, Clinic for Craniomaxillofacial Surgery, University
for
Craniomaxillofacial
Surgery,
University
Hospital,
R€amistrasse 100, 8091 Z€ urich, Switzerland; e-mail: [email protected]
Hospital, Zurich, Switzerland.
Received February 23 2015
xAdjunct Professor, Department of Biostatistics, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich,
Ó 2015 American Association of Oral and Maxillofacial Surgeons
Switzerland.
0278-2391/15/00894-0
Accepted June 18 2015
kProfessor and Medical Director, Clinic for Craniomaxillofacial
http://dx.doi.org/10.1016/j.joms.2015.06.159
Surgery, University Hospital, Zurich, Switzerland. {Fellow, Clinic for Craniomaxillofacial Surgery, University Hospital, Zurich, Switzerland.
1.e1 FLA 5.2.0 DTD YJOMS56884_proof 11 July 2015 4:47 pm CE AH
57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112
113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168
1.e2
MIRROR CT FOR SURGICAL REVISION
Conclusion:
Q3
This study showed that of 6 of 7 actual revisions, implant placement would have been revised intraoperatively by all 4 examiners, if intraoperative imaging with computer-assisted virtual reconstruction of the orbit would have been applied. Therefore, the authors suggest that intraoperative imaging with computer-assisted virtual reconstruction could be advantageous in the prevention of later revisions of orbital floor fractures. In this study, the threshold to revise implant placement intraoperatively seemed to be lower when using intraoperative imaging with virtual reconstructions, because considerably more cases would have been revised intraoperatively by the examiners. In the in-hospital and post-hospital phases, this threshold increased, suggesting the more important role of clinical findings. It is uncertain whether the actual surgeons would have revised the same cases as the examiners if they had used intraoperative imaging with virtual reconstructions for their deliberation. However, the intraoperative interrater agreement was good and cost-intensive postoperative revisions might be prevented. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1.e1-1.e9, 2015 Orbital floor fractures are common in midfacial fractures1 deriving from facial trauma. Various studies have discussed indications and timing for operative repair of orbital floor fractures because oculofacial surgery is not without risk.2 If not operated on in time and appropriately, then complications, such as enophthalmia or diplopia, can occur.3-6 New surgical and imaging techniques have improved the functional and esthetic outcomes of reconstructions,6-8 and surgical navigation has become an established technique in oral and maxillofacial surgery.9-12 Intraoperative multidetector computed tomographic (CT) and cone-beam CT (CBCT) scans to confirm ideal reconstruction have been described in the literature as effective.13-24 However, to the authors’ knowledge, no study has investigated the influence of computer-assisted virtual reconstructions of the orbit on a surgeon’s decision to revise a reconstruction of an orbital floor fracture. The aim of this study was to test whether a surgeon would revise the result of a primary orbital floor reconstruction by reviewing a mirrored postoperative CT scan at 3 particular times: 1) intraoperatively before wound closure, 2) during inpatient hospitalization, and 3) after hospitalization. The extent to which these revisions correspond to effectively revised cases is based on clinical results. This is a means to evaluate whether intraoperative imaging is advantageous.
Material and Methods Anonymized postoperative CT scans of 51 patients with a reconstructed unilateral orbital floor fracture were included in this study. Postoperative imaging was conducted from September 2009 through December 2012 in the Clinic for Craniomaxillofacial Surgery at the Universit€atsspital Zurich (Zurich, Switzerland). None of the patients underwent intraoperative imaging during the surgical procedure. Seven of the 51 patients subsequently underwent revision surgery after the surgical repair.
These postoperative CT scans were imported into Brainlab iPlan Net software (Brainlab AG, Feldkirchen, Germany) as described in a previous study.14 The autosegmentation function of the program was used on the unaffected orbit to obtain a virtual 3-dimensional (3D) template. Then, the computed 3D template was controlled and manually trimmed using the provided software tools, if necessary (Fig 1). This 3D template was mirrored and manually superimposed to the best fit onto the affected orbit using the orbital roof in the sagittal plane and the orbital rim in the coronal plane as landmarks (Fig 1). Then, these modified postoperative CT scans were saved on the clinic server as Digital Imaging and Communications in Medicine (DICOM) datasets to be analyzed by the examiners. Information about the affected side, injury pattern, and materials used for reconstruction (polydioxanone [PDS], titanium mesh, or PDS and titanium Q4 mesh) was assessed using these anonymized postoperative CT scans. Subsequently, whether a surgeon would revise the surgically repaired orbital floor fracture was analyzed using the datasets. Examiners assessed the postoperative CT scans with the mirrored, unaffected orbit as reference. Deliberate clinical symptoms were not included. Two experienced consultants (examiners 1 and 3) and 2 residents (examiners 2 and 4) analyzed the datasets and decided whether a revision was favorable. The deliberations were separated for 3 different periods: 1) when the surgeon would see the CT scan intraoperatively before closing the surgical access, 2) during inpatient hospitalization, and 3) after hospitalization. These results were analyzed for inter-rater agreement, and the examiners’ intentions to revise were compared with the actual revisions. Each measurement was analyzed for the entire study population, for cases treated with PDS, and for cases treated with titanium mesh. Statistical analyses for the patient population were performed using Excel (Microsoft Corporation,
FLA 5.2.0 DTD YJOMS56884_proof 11 July 2015 4:47 pm CE AH
Q1
169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224
1.e3
225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280
web 4C=FPO
BLUMER ET AL
FIGURE 1. The auto-segmentation function of the software was used on the unaffected orbit for a computed 3-dimensional template (green). This template was searched for possible errors and manually trimmed when needed. Then, the template was mirrored and superimposed, resulting in virtual reconstruction of the affected orbit (red). In this case, the virtual reconstruction of the fractured orbit shows the correct shape and position of the implant. Blumer et al. Mirror CT for Surgical Revision. J Oral Maxillofac Surg 2015.
Redmond, WA). The inter-rater agreement was assessed using the Fleiss k value.25 For these calculations, STATA 13.1 (StataCorp LP, College Station, TX) was used. To calculate the 95% confidence interval (CI) 5,000 bootstrap replications were applied. Agreement between examiners is usually graded according to the method of Landis and Koch26 as poor (
