- Email: [email protected]
Improved Temporomandibular Joint Position After 3-Dimensional Planned Mandibular Reconstruction
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SURGICAL ONCOLOGY AND RECONSTRUCTION
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Improved Temporomandibular Joint Position After 3-Dimensional Planned Mandibular Reconstruction Rajendra Sawh-Martinez, MD,* Yassmin Parsaei, BA,y Robin Wu, BA,z Alexander Lin, BA,x Philipp Metzler, MD, DMD,k Christopher DeSesa, DMD,{ and Derek M. Steinbacher, MD, DMD#
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Purpose:
Virtual surgical planning (VSP) using computer-aided design and manufacturing (CAD-CAM) has been reported to aid in craniofacial reconstruction. The reported improvements have been related mainly to operative performance, with limited evaluations of the position and function of the temporomandibular joint (TMJ). This study analyzed the radiographic detail of postoperative outcomes related to the TMJ.
Materials and Methods:
Patients who underwent mandibular reconstruction with and without VSP were analyzed. All patients underwent preoperative computed tomography (CT) of their mandible. In the VSP group, CAD-CAM planning was performed preoperatively using CT Digital Imaging and Communications in Medicine (DICOM) data. Postoperative CT images from the 2 groups were quantitatively compared to evaluate the TMJ. CT images were digitized for 2- and 3-dimensional analysis using surgical planning software (Materialise, Leuven, Belgium). Anatomic landmarks and cephalometric relations were analyzed.
Results:
Sixteen patients who underwent traditional planning or VSP for mandibular reconstruction were compared. Two groups (n = 8 each) were compared for positioning of the mandibular condyle in the glenoid fossa. Measurements of superior, anterior, and lateral movements were comparable in the pre- and postoperative groups for the traditional and VSP groups (P < .001 by analysis of variance). Subgroup analysis evaluating ipsilateral changes in the mandibular condyle position for traditional planning versus VSP noted decreased percentages of change in superior (22 vs 10%; P < .1), anterior (32 vs 15%; P < .1), and lateral (7 vs 1%, not significant) shifts of the condyle for left mandibular reconstructions (n = 8). Ipsilateral right mandibular reconstructions (n = 6) showed changes in superior (62 vs 15%; P < .1) and anterior (5 vs 9%; not significant) shifts.
Conclusion:
These data showed comparable pre- and postoperative positions of the TMJ for traditional and VSP mandibular reconstructions. Evaluation of condyle movements showed differences in the ipsilateral position in the pre- and postoperative groups. VSP resulted in decreased superior and lateral shifts of the ipsilateral condyle and decreased changes in the condylar and condylar neck angles. This work shows
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*Resident, Section of Plastic Surgery, Yale University School of Medicine, New Haven, CT.
This work and abstract was presented and published at the 97th Annual Meeting of the American Association of Oral and Maxillofa-
yDental Student, University of Pennsylvania School of Dental
cial Surgeons; Washington, DC; October 2, 2015.
Medicine, Philadelphia, PA.
Address correspondence and reprint requests to Dr Steinbacher:
zMedical Student, Section of Plastic Surgery, Yale University
Department of Surgery, Associate Professor of Plastic Surgery, Chief
School of Medicine, New Haven, CT.
of Oral and Maxillofacial Surgery, Chief of Dentistry, Director of
xMedical Student, Quinnipiac University, New Haven, CT.
Craniofacial Surgery, Yale University School of Medicine, PO Box
kResearch Fellow, Section of Plastic Surgery, Yale University
8041, New Haven, CT 06520-8062; e-mail: derek.steinbacher@
School of Medicine, New Haven, CT. {Resident, Section of Oral and Maxillofacial Surgery, Yale
gmail.com Received April 13 2016
University School of Medicine, New Haven, CT.
Accepted July 28 2016 Ó 2016 Published by Elsevier Inc on behalf of the American Association of Oral
#Associate Professor, Department of Plastic Surgery; Chief, Department of Oral and Maxillofacial Surgery; Chief, Department
and Maxillofacial Surgeons
of Dentistry; Director, Department of Craniofacial Surgery, Yale
0278-2391/16/30691-7
University School of Medicine, New Haven, CT.
http://dx.doi.org/10.1016/j.joms.2016.07.032
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TMJ POSITION AFTER VIRTUAL RECONSTRUCTION
that VSP can lead to increased precision in reconstruction leading to preserved normative anatomic relations. Ó 2016 Published by Elsevier Inc on behalf of the American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1-8, 2016
The free fibula flap (FFF) has become the preferred method for mandibular reconstruction.1-5 Fibula bone stock is generous and supports dental implants. Peroneal artery vessel diameter allows for microsurgical transfer without vein grafts and the blood supply permits flexible osteotomies to match the mandibular shape. The primary goal of mandibular reconstruction is to achieve restoration of contour, lining of intraoral contents, and preserved masticatory function. This requires precise size and placement of the fibular construct, requisite osteotomies, and native mandibular positioning. In particular, it is essential to preserve function at the temporomandibular joint (TMJ) to allow for adequate mandibular mobility and mastication and to mitigate trismus or dislocation. TMJ malposition after trauma, reconstruction, or orthognathic surgery can result in TMJ pain, clicking, or malocclusion.6 TMJ ankylosis also can develop, requiring future surgeries to correct.7-9 Virtual surgical planning (VSP) using computeraided design and manufacturing has become an important aid to mandibular reconstruction.10-17 This technology allows surgeons to digitally visualize defects and then preplan osteotomies by creating surgical resection guides and plating templates. VSP in FFF mandibular reconstruction has shown reproducible and accurate postoperative outcomes, particularly in patients requiring multiple fibular segments.18,19 Additional benefits include shorter operative times by increased precision in the reconstructed bony interface.17-20 However, TMJ position after mandibular reconstruction with and without VSP has not been directly compared. The purpose of this study was to evaluate TMJ functional outcomes in FFF mandibular reconstructions with and without VSP by analyzing digitized 3dimensional (3D) computed tomographic (CT) images. The specific aims were to compare linear spatial TMJ dimensions using pre- and postoperative 3D CT images. The authors hypothesized that VSP would result in less displacement and improved correlation with the preoperative (normal) condylar position compared with the free-hand technique.
Patients were excluded if CT documentation was not available. This study was performed in concordance with the institutional review board of the Yale University School of Medicine (New Haven, CT; HIC number 1101007932). All patients underwent preoperative CT scanning of their mandible. Patients’ age, gender, diagnosis, and perioperative details were documented. Patients who had preoperative VSP had their CT Digital Imaging and Communications in Medicine (DICOM) data digitally sent for virtual analysis. VSP included creating the resection defect and developing the fibula size and osteotomies needed for reconstruction. Patient-specific cutting guides and pre-bent 2.4-mm mandibular reconstruction plates were at- Q3 tained for each patient who had VSP as part of their operative plan (Synthes, Solothurn, Switzerland). CT data for patients who underwent mandibular reconstruction with and without VSP were analyzed. CT images were digitized for 2-dimensional and 3D analysis using the surgical planning software Mimics 10.01 (Materialise, Leuven, Belgium). Anatomic landmarks and cephalometric relations were analyzed with specific evaluation of condylar relations with the TMJ (Table 1). The authors chose these landmarks, distances, and angles for their clinical relevance and to attain a detailed anatomic analysis of the TMJ space. Two observers who did not partake in the VSP or surgical reconstructions performed the measurements and statistical comparisons. Angular and distance measurements were attained for multiple relations of the TMJ (Table 1). These data points were converted to percentages of change to compare pre- and postoperative data. Then, the data were evaluated to determine changes in TMJ position relative to ipsilateral mandibular reconstruction for patients who underwent traditional or VSP mandibular reconstruction. Percentages were rounded for ease of reporting; exact numbers are stated on the figures. Statistical analysis of the data was carried out using analysis of variance for multi-group comparison, and the Student t test was used to compare pre- and postoperative data points. P values less than .05 were considered statistically significant.
Results Materials and Methods Patients who underwent mandibular reconstruction using the FFF from 2011 through 2014 were evaluated.
DEMOGRAPHICS
Sixteen patients who underwent mandibular reconstruction were analyzed. The average age of the
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Table 1. ANATOMIC LANDMARKS AND CEPHALOMETRIC RELATIONS SPECIFICALLY FOR CONDYLAR RELATIONS WITH THE TEMPOROMANDIBULAR JOINT, WITH REPRESENTATIVE SCREENSHOTS (A, B, C)
Distances Anterior shift Superior shift Lateral shift Intercondylar distance Angle measurements Condylar neck angle Intercondylar angle Condylar neck sagittal angle Condylar angle L and R Intercondylar neck angle
Condylar midpoint L and coronal plane Condylar midpoint L and R and FH Midsagittal plane and condylar midpoint L and R Medial R and medial L Condylar neck LL and midsagittal plane (L and R) Condylar head line L and condylar headline R Condylar neck line L and R and coronal plane Condylar head line L and R and midsagittal plane comparing the 2 sides Condylar neck line L and condylar neck line R
Abbreviations: EAM, ---; FH, Frankfurt horizontal plane; L, left; LAM, ---; R, right. Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
patients was 61.6 years (range, 33 to 89 yr). The cohort was comprised predominantly of men (75%; 12 of 16). Smokers comprised 81% of patients. The pathology leading to mandibular segment resection was mostly squamous cell carcinoma, which comprised 75% of the study group. The remaining indications included osteomyelitis, gunshot wound, adenoid cystic carcinoma, and myxoma (6.25%; 1 each of 16). The left side of the mandible was involved in 50% of cases, the right side was involved in 37.5% of cases, and the midline was involved in 12.5% of cases. The average duration of follow-up was 16.2 months (range, 3 to 51.6 months; Table 2). SURGICAL TECHNIQUE
Intraoperatively, the plate was placed spanning the defect and temporarily secured to the mandibular segments with at least 2 screws on either side. Then, the plate was removed and taken to the leg, where the fibula segments were adapted to the plate, before separation of the vascular pedicle. Patients who underwent mandibular resection and reconstruction without VSP had their fibular osteotomies performed ‘‘free-handed’’ intraoperatively. Segment lengths and position were determined intraoperatively from measurements of the resected mandible and resultant defect. A pre-bent 2.4-mm mandibular reconstruction plate also was used to
achieve bony alignment. Similarly, this was fixed while spanning the defect intraorally. The intervening segment was marked on the plate, and this was taken to the leg. Then, the fibular osteotomies were made to approximate the needed bony contour and length. A contouring burr was used to correct any bony interference. Once the fibula segments were satisfactorily adapted to the reconstruction plate in the 2 groups, the vascular pedicles were divided and taken to the head. Then, the fibula construct attached to the plate was fixated to the remaining native mandible. Microsurgical vascular anastomosis was carried out. Postoperative CT scans with 3D reconstructions were attained during the first postoperative week. MEASUREMENTS
Thirty-two CT scans were analyzed for detailed condylar relations. The average values for pre- and postoperative distances and angle measurements were recorded for the traditional group and the VSP group (Figs 1, 2). The overall percentage of change (Fig 3) showed a statistically significant difference between the traditional and VSP groups in the superior condylar shift of the right and left condyles (right condyle, 36 vs 20%; left condyle, 24 vs 11%; P < .05) and a lateral shift of the left condyle (10 vs 0.2%; P < .01).
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Table 2. PATIENT DEMOGRAPHICS
Patient Number Gender 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 t test
M M M M M M F F M M M M M M F F 1.00
Age 65 63 66 61 60 64 65 60 63 66 65 47 39 79 89 33 0.68
Ability Smoking Alcohol Postoperative Follow-Up Return of Dental to Chew VSP Hx Hx Radiation Time (mo) Ankylosis Speech Implants or Eat No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes NA
1 1 1 1 1 1 1 1 1 1 0 1 1 0 1 0 0.06
1 0 1 0 0 0 0 0 0 1 0 0 1 0 0 1 0.62
0 0 1 0 1 1 0 1 0 1 0 1 0 0 1 1 1.00
3 16 52 3 11 7 3 49 7 22 4 32 9 4 17 21 0.68
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 NA
0 1 1 0 1 1 0 1 1 1 0 1 1 0 1 1 0.62
0 1 1 0 1 1 0 1 0 1 0 1 1 0 1 1 1.00
Abbreviations: F, female; Hx, habit; M, male; NA, not applicable; VSP, virtual surgical planning.
0 1 1 0 1 1 0 1 1 1 0 1 1 0 0 1 1.00 Q6
Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
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FIGURE 1. Measurements for traditional group. A, Movement measurements. B, Angle measurements. L, left; R, right. Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
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FIGURE 2. Measurements for VSP group. A, Movement measurements. B, Angle measurements. L, left; R, right; VSP, virtual surgical planning. Q9 Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
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SAWH-MARTINEZ ET AL
FIGURE 3. Overall percentage of change of temporomandibular joint relations from pre- to postoperatively using traditional or VSP mandibQ10 ular reconstruction. L, left; R, right; VSP, virtual surgical planning. Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
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FIGURE 4. Percentages of ipsilateral and contralateral temporomandibular joint change after traditional or VSP mandibular reconstruction. A, Left-side temporomandibular joint changes after left-side mandibular reconstruction. B, Right-side temporomandibular joint changes after leftside mandibular reconstruction. (Fig 4 continued on next page.) Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
Patients who underwent left mandibular reconstruction exhibited statistically relevant changes in ipsilateral and contralateral TMJ positional and angular percentages of change (Fig 4). Patients who underwent left mandibular reconstruction showed a statistically significant percentage of change in the ipsilateral superior and anterior shifts (superior shift, 22 vs 10%; anterior shift, 32 vs 15%; P < .05). The ipsilateral condylar neck angle exhibited the greatest difference in percentage of change from pre- to postoperatively, when traditional and VSP mandibular reconstruction groups were evaluated (condylar neck angle, 72 vs 2.68%; P < .01; Fig 4A). The contralateral TMJ after left mandibular reconstruction showed a statistically significant difference in the condylar neck angle (71 vs 49%; P < .05) on the right
and the intercondylar neck angle (32 vs 6.7%; P < .05; Fig 4B). Patients who underwent right mandibular reconstruction showed statistically relevant differences in the percentage of change in pre- to postoperative ipsilateral and contralateral TMJ superior shifts. Ipsilateral and contralateral superior shift changes from pre- to postoperatively were 61.7 versus 14.7% (P < .05) and 45 versus 12.6% (P < .05), respectively (Fig 4C, D).
Discussion VSP is a critical tool in the reconstructive armamentarium. Given the digital manipulation and ability to quantitatively direct the operative plan, it is believed to enable improved precision and
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FIGURE 4 (cont’d). C, Right-side temporomandibular joint changes after right-side mandibular reconstruction. D, Left-side temporomandibular joint changes after right-side mandibular reconstruction. L, left; R, right; VSP, virtual surgical planning. Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
predictability.18-20 Prior studies evaluating complex microvascular mandibular reconstruction have focused on the relations of the bony construct. No studies have yet evaluated the complex condylar position and its alteration after reconstruction using VSP. In the present study, the authors evaluated the positional and angular changes of various anatomic landmarks as they relate to the TMJ position preand postoperatively in patients who underwent mandibular reconstruction with or without VSP. VSP enhances the ability to create precise bony segments with 3D printed cutting guides that are specific to a planned resection defect. Prior studies have reported improved bony apposition and decreased operative times.17-19 Pre-bent plates allow for faster securing of bony segments and improved contact between osteotomy segments. With improved precision of fixating the fibular segments to the native mandible, less theoretical displacement can be achieved, thus preserving TMJ position and presumed function. The present data showed a decreased percentage of change in the mandibular position postoperatively when VSP was used. This could be attributable to
the ability to custom create cutting guides, precise osteotomies, and smaller bony gaps or interferences as described in prior studies.17-20 Of note, the greater stability of the condylar position with VSP for mandibular reconstruction was noted to occur at the ipsilateral and contralateral TMJs. Consistently large decreases in superior condylar displacement were noted when VSP was used. Although these data do not represent active functional data of the joint, the authors presume that greater positional stability will lead to preservation of preoperative function, although this was not tested. Given the serious overall morbidity with mandibular resection and reconstruction, higher-order functional outcomes are difficult to ascertain. Notable surgical outcomes of normative occlusion, placement of dental implants, speech, and swallow functions were attained in the 2 groups without statistical differences. Precise TMJ function and degree of rotation were not routinely measured preoperatively, precluding analysis. These data point to the added utility of VSP, which aides in the positioning of mandibular segments
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TMJ POSITION AFTER VIRTUAL RECONSTRUCTION
during reconstruction. Having cutting guides based on the surgical plan, the mandibular segments fit together with added precision intraoperatively, decreasing the need for manipulation of mandibular segments that can affect the movement of the TMJ. Prior studies have reported an increased reproducibility of spatial positioning of the mandibular segments during reconstruction.17-20 The effect of reconstruction on the anatomic position of the TMJ has not been explored previously but is a key component of postoperative patient functionality. In total TMJ reconstruction, the joint retains its function as a hinge but loses its ability for full translation. For mandibular segmental reconstruction, the condyle might be positioned out of its native joint. The presumption has been that the attached ligaments and joint capsule allow for maintenance of position; however, there can be disc displacement and postoperative ankylosis. These outcomes have been seldom evaluated, because there have been limited alternative methods to improve surgical accuracy before VSP. TMJ position is affected by the position and placement of segments in mandibular reconstruction. VSP can lead to increased precision in this reconstruction, preserving normative anatomic relations at the TMJ that can directly affect joint function. Long-term outcome studies of TMJ motion analysis are needed to evaluate whether there is improved clinical functionality. The present data showed comparable pre- and postoperative positions of the TMJ for traditional and VSP mandibular reconstructions. Evaluation of condyle movements showed differences in ipsilateral position in pre- and postoperative groups. VSP resulted in decreased superior and lateral shifts of the ipsilateral condyle and decreased changes in the condylar and condylar neck angles. This work shows that VSP can lead to increased precision in reconstruction, leading to preserved normative anatomic relations.
References 1. Hidalgo DA, Rekow A: A review of 60 consecutive fibula free flap mandible reconstructions. Plast Reconstr Surg 96:585, 1995
2. Hidalgo DA: Fibula free flap: A new method of mandible reconstruction. Plast Reconstr Surg 84:71, 1989 3. Wolff KD, Ervens J, Herzog K, et al: Experience with the osteocutaneous fibula flap: An analysis of 24 consecutive reconstructions of composite mandibular defects. J Craniomaxillofac Surg 24:330, 1996 4. Urken ML, Weinberg H, Vickery C, et al: Oromandibular reconstruction using microvascular composite free flaps. Report of 71 cases and a new classification scheme for bony, soft-tissue, and neurologic defects. Arch Otolaryngol Head Neck Surg 117:733, 1991 5. Cordeiro PG, Hidalgo DA: Conceptual considerations in mandibular reconstruction. Clin Plast Surg 22:61, 1995 6. Wolford LM, Reiche-Fischel O, Mehra P: Changes in temporomandibular joint dysfunction after orthognathic surgery. J Oral Maxillofac Surg 61:655, 2003 7. Raveh J, Vuillemin T, Ladrach K, et al: Temporomandibular joint ankylosis: Surgical treatment and long-term results. J Oral Maxillofac Surg 47:900, 1989 8. Kaban LB, Perrott DH, Fisher K: A protocol for management of temporomandibular joint ankylosis. J Oral Maxillofac Surg 48: 1145, 1990 9. Chidzonga MM: Temporomandibular joint ankylosis: Review of thirty-two cases. Br J Oral Maxillofac Surg 37:123, 1999 10. Ciocca L, Mazzoni S, Fantini M, et al: CAD/CAM guided secondary mandibular reconstruction of a discontinuity defect after ablative cancer surgery. J Craniomaxillofac Surg 40:e511, 2012 11. Derand P, Hirsch JM: Virtual bending of mandibular reconstruction plates using a computer-aided design. J Oral Maxillofac Surg 67:1640, 2009 12. Gateno J, Teichgraeber JF, Aguilar E: Computer planning for distraction osteogenesis. Plast Reconstr Surg 105:873, 2000 13. Hassfeld S, Muhling J: Computer assisted oral and maxillofacial surgery—A review and an assessment of technology. Int J Oral Maxillofac Surg 30:2, 2001 14. Hsu SS, Gateno J, Bell RB, et al: Accuracy of a computer-aided surgical simulation protocol for orthognathic surgery: A prospective multicenter study. J Oral Maxillofac Surg 71:128, 2013 15. Hirsch DL, Garfein ES, Christensen AM, et al: Use of computeraided design and computer-aided manufacturing to produce orthognathically ideal surgical outcomes: A paradigm shift in head and neck reconstruction. J Oral Maxillofac Surg 67:2115, 2009 16. Tepper OM, Sorice S, Hershman GN, et al: Use of virtual 3-dimensional surgery in post-traumatic craniomaxillofacial reconstruction. J Oral Maxillofac Surg 69:733, 2011 17. Eckardt A, Swennen GR: Virtual planning of composite mandibular reconstruction with free fibula bone graft. J Craniofac Surg 16:1137, 2005 18. Metzler P, Geiger EJ, Alcon A, et al: Three-dimensional virtual surgery accuracy for free fibula mandibular reconstruction: Planned versus actual results. J Oral Maxillofac Surg 72:2601, 2014 19. Foley BD, Thayer WP, Honeybrook A, et al: Mandibular reconstruction using computer-aided design and computer-aided manufacturing: An analysis of surgical results. J Oral Maxillofac Surg 71:e111, 2013 20. Stirling Craig E, Yuhasz M, Shah A, et al: Simulated surgery and cutting guides enhance spatial positioning in free fibular mandibular reconstruction. Microsurgery 35:29, 2014
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SURGICAL ONCOLOGY AND RECONSTRUCTION
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Improved Temporomandibular Joint Position After 3-Dimensional Planned Mandibular Reconstruction Rajendra Sawh-Martinez, MD,* Yassmin Parsaei, BA,y Robin Wu, BA,z Alexander Lin, BA,x Philipp Metzler, MD, DMD,k Christopher DeSesa, DMD,{ and Derek M. Steinbacher, MD, DMD#
Q15
Purpose:
Virtual surgical planning (VSP) using computer-aided design and manufacturing (CAD-CAM) has been reported to aid in craniofacial reconstruction. The reported improvements have been related mainly to operative performance, with limited evaluations of the position and function of the temporomandibular joint (TMJ). This study analyzed the radiographic detail of postoperative outcomes related to the TMJ.
Materials and Methods:
Patients who underwent mandibular reconstruction with and without VSP were analyzed. All patients underwent preoperative computed tomography (CT) of their mandible. In the VSP group, CAD-CAM planning was performed preoperatively using CT Digital Imaging and Communications in Medicine (DICOM) data. Postoperative CT images from the 2 groups were quantitatively compared to evaluate the TMJ. CT images were digitized for 2- and 3-dimensional analysis using surgical planning software (Materialise, Leuven, Belgium). Anatomic landmarks and cephalometric relations were analyzed.
Results:
Sixteen patients who underwent traditional planning or VSP for mandibular reconstruction were compared. Two groups (n = 8 each) were compared for positioning of the mandibular condyle in the glenoid fossa. Measurements of superior, anterior, and lateral movements were comparable in the pre- and postoperative groups for the traditional and VSP groups (P < .001 by analysis of variance). Subgroup analysis evaluating ipsilateral changes in the mandibular condyle position for traditional planning versus VSP noted decreased percentages of change in superior (22 vs 10%; P < .1), anterior (32 vs 15%; P < .1), and lateral (7 vs 1%, not significant) shifts of the condyle for left mandibular reconstructions (n = 8). Ipsilateral right mandibular reconstructions (n = 6) showed changes in superior (62 vs 15%; P < .1) and anterior (5 vs 9%; not significant) shifts.
Conclusion:
These data showed comparable pre- and postoperative positions of the TMJ for traditional and VSP mandibular reconstructions. Evaluation of condyle movements showed differences in the ipsilateral position in the pre- and postoperative groups. VSP resulted in decreased superior and lateral shifts of the ipsilateral condyle and decreased changes in the condylar and condylar neck angles. This work shows
Q5
*Resident, Section of Plastic Surgery, Yale University School of Medicine, New Haven, CT.
This work and abstract was presented and published at the 97th Annual Meeting of the American Association of Oral and Maxillofa-
yDental Student, University of Pennsylvania School of Dental
cial Surgeons; Washington, DC; October 2, 2015.
Medicine, Philadelphia, PA.
Address correspondence and reprint requests to Dr Steinbacher:
zMedical Student, Section of Plastic Surgery, Yale University
Department of Surgery, Associate Professor of Plastic Surgery, Chief
School of Medicine, New Haven, CT.
of Oral and Maxillofacial Surgery, Chief of Dentistry, Director of
xMedical Student, Quinnipiac University, New Haven, CT.
Craniofacial Surgery, Yale University School of Medicine, PO Box
kResearch Fellow, Section of Plastic Surgery, Yale University
8041, New Haven, CT 06520-8062; e-mail: derek.steinbacher@
School of Medicine, New Haven, CT. {Resident, Section of Oral and Maxillofacial Surgery, Yale
gmail.com Received April 13 2016
University School of Medicine, New Haven, CT.
Accepted July 28 2016 Ó 2016 Published by Elsevier Inc on behalf of the American Association of Oral
#Associate Professor, Department of Plastic Surgery; Chief, Department of Oral and Maxillofacial Surgery; Chief, Department
and Maxillofacial Surgeons
of Dentistry; Director, Department of Craniofacial Surgery, Yale
0278-2391/16/30691-7
University School of Medicine, New Haven, CT.
http://dx.doi.org/10.1016/j.joms.2016.07.032
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that VSP can lead to increased precision in reconstruction leading to preserved normative anatomic relations. Ó 2016 Published by Elsevier Inc on behalf of the American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1-8, 2016
The free fibula flap (FFF) has become the preferred method for mandibular reconstruction.1-5 Fibula bone stock is generous and supports dental implants. Peroneal artery vessel diameter allows for microsurgical transfer without vein grafts and the blood supply permits flexible osteotomies to match the mandibular shape. The primary goal of mandibular reconstruction is to achieve restoration of contour, lining of intraoral contents, and preserved masticatory function. This requires precise size and placement of the fibular construct, requisite osteotomies, and native mandibular positioning. In particular, it is essential to preserve function at the temporomandibular joint (TMJ) to allow for adequate mandibular mobility and mastication and to mitigate trismus or dislocation. TMJ malposition after trauma, reconstruction, or orthognathic surgery can result in TMJ pain, clicking, or malocclusion.6 TMJ ankylosis also can develop, requiring future surgeries to correct.7-9 Virtual surgical planning (VSP) using computeraided design and manufacturing has become an important aid to mandibular reconstruction.10-17 This technology allows surgeons to digitally visualize defects and then preplan osteotomies by creating surgical resection guides and plating templates. VSP in FFF mandibular reconstruction has shown reproducible and accurate postoperative outcomes, particularly in patients requiring multiple fibular segments.18,19 Additional benefits include shorter operative times by increased precision in the reconstructed bony interface.17-20 However, TMJ position after mandibular reconstruction with and without VSP has not been directly compared. The purpose of this study was to evaluate TMJ functional outcomes in FFF mandibular reconstructions with and without VSP by analyzing digitized 3dimensional (3D) computed tomographic (CT) images. The specific aims were to compare linear spatial TMJ dimensions using pre- and postoperative 3D CT images. The authors hypothesized that VSP would result in less displacement and improved correlation with the preoperative (normal) condylar position compared with the free-hand technique.
Patients were excluded if CT documentation was not available. This study was performed in concordance with the institutional review board of the Yale University School of Medicine (New Haven, CT; HIC number 1101007932). All patients underwent preoperative CT scanning of their mandible. Patients’ age, gender, diagnosis, and perioperative details were documented. Patients who had preoperative VSP had their CT Digital Imaging and Communications in Medicine (DICOM) data digitally sent for virtual analysis. VSP included creating the resection defect and developing the fibula size and osteotomies needed for reconstruction. Patient-specific cutting guides and pre-bent 2.4-mm mandibular reconstruction plates were at- Q3 tained for each patient who had VSP as part of their operative plan (Synthes, Solothurn, Switzerland). CT data for patients who underwent mandibular reconstruction with and without VSP were analyzed. CT images were digitized for 2-dimensional and 3D analysis using the surgical planning software Mimics 10.01 (Materialise, Leuven, Belgium). Anatomic landmarks and cephalometric relations were analyzed with specific evaluation of condylar relations with the TMJ (Table 1). The authors chose these landmarks, distances, and angles for their clinical relevance and to attain a detailed anatomic analysis of the TMJ space. Two observers who did not partake in the VSP or surgical reconstructions performed the measurements and statistical comparisons. Angular and distance measurements were attained for multiple relations of the TMJ (Table 1). These data points were converted to percentages of change to compare pre- and postoperative data. Then, the data were evaluated to determine changes in TMJ position relative to ipsilateral mandibular reconstruction for patients who underwent traditional or VSP mandibular reconstruction. Percentages were rounded for ease of reporting; exact numbers are stated on the figures. Statistical analysis of the data was carried out using analysis of variance for multi-group comparison, and the Student t test was used to compare pre- and postoperative data points. P values less than .05 were considered statistically significant.
Results Materials and Methods Patients who underwent mandibular reconstruction using the FFF from 2011 through 2014 were evaluated.
DEMOGRAPHICS
Sixteen patients who underwent mandibular reconstruction were analyzed. The average age of the
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Table 1. ANATOMIC LANDMARKS AND CEPHALOMETRIC RELATIONS SPECIFICALLY FOR CONDYLAR RELATIONS WITH THE TEMPOROMANDIBULAR JOINT, WITH REPRESENTATIVE SCREENSHOTS (A, B, C)
Distances Anterior shift Superior shift Lateral shift Intercondylar distance Angle measurements Condylar neck angle Intercondylar angle Condylar neck sagittal angle Condylar angle L and R Intercondylar neck angle
Condylar midpoint L and coronal plane Condylar midpoint L and R and FH Midsagittal plane and condylar midpoint L and R Medial R and medial L Condylar neck LL and midsagittal plane (L and R) Condylar head line L and condylar headline R Condylar neck line L and R and coronal plane Condylar head line L and R and midsagittal plane comparing the 2 sides Condylar neck line L and condylar neck line R
Abbreviations: EAM, ---; FH, Frankfurt horizontal plane; L, left; LAM, ---; R, right. Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
patients was 61.6 years (range, 33 to 89 yr). The cohort was comprised predominantly of men (75%; 12 of 16). Smokers comprised 81% of patients. The pathology leading to mandibular segment resection was mostly squamous cell carcinoma, which comprised 75% of the study group. The remaining indications included osteomyelitis, gunshot wound, adenoid cystic carcinoma, and myxoma (6.25%; 1 each of 16). The left side of the mandible was involved in 50% of cases, the right side was involved in 37.5% of cases, and the midline was involved in 12.5% of cases. The average duration of follow-up was 16.2 months (range, 3 to 51.6 months; Table 2). SURGICAL TECHNIQUE
Intraoperatively, the plate was placed spanning the defect and temporarily secured to the mandibular segments with at least 2 screws on either side. Then, the plate was removed and taken to the leg, where the fibula segments were adapted to the plate, before separation of the vascular pedicle. Patients who underwent mandibular resection and reconstruction without VSP had their fibular osteotomies performed ‘‘free-handed’’ intraoperatively. Segment lengths and position were determined intraoperatively from measurements of the resected mandible and resultant defect. A pre-bent 2.4-mm mandibular reconstruction plate also was used to
achieve bony alignment. Similarly, this was fixed while spanning the defect intraorally. The intervening segment was marked on the plate, and this was taken to the leg. Then, the fibular osteotomies were made to approximate the needed bony contour and length. A contouring burr was used to correct any bony interference. Once the fibula segments were satisfactorily adapted to the reconstruction plate in the 2 groups, the vascular pedicles were divided and taken to the head. Then, the fibula construct attached to the plate was fixated to the remaining native mandible. Microsurgical vascular anastomosis was carried out. Postoperative CT scans with 3D reconstructions were attained during the first postoperative week. MEASUREMENTS
Thirty-two CT scans were analyzed for detailed condylar relations. The average values for pre- and postoperative distances and angle measurements were recorded for the traditional group and the VSP group (Figs 1, 2). The overall percentage of change (Fig 3) showed a statistically significant difference between the traditional and VSP groups in the superior condylar shift of the right and left condyles (right condyle, 36 vs 20%; left condyle, 24 vs 11%; P < .05) and a lateral shift of the left condyle (10 vs 0.2%; P < .01).
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Table 2. PATIENT DEMOGRAPHICS
Patient Number Gender 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 t test
M M M M M M F F M M M M M M F F 1.00
Age 65 63 66 61 60 64 65 60 63 66 65 47 39 79 89 33 0.68
Ability Smoking Alcohol Postoperative Follow-Up Return of Dental to Chew VSP Hx Hx Radiation Time (mo) Ankylosis Speech Implants or Eat No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes NA
1 1 1 1 1 1 1 1 1 1 0 1 1 0 1 0 0.06
1 0 1 0 0 0 0 0 0 1 0 0 1 0 0 1 0.62
0 0 1 0 1 1 0 1 0 1 0 1 0 0 1 1 1.00
3 16 52 3 11 7 3 49 7 22 4 32 9 4 17 21 0.68
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 NA
0 1 1 0 1 1 0 1 1 1 0 1 1 0 1 1 0.62
0 1 1 0 1 1 0 1 0 1 0 1 1 0 1 1 1.00
Abbreviations: F, female; Hx, habit; M, male; NA, not applicable; VSP, virtual surgical planning.
0 1 1 0 1 1 0 1 1 1 0 1 1 0 0 1 1.00 Q6
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FIGURE 1. Measurements for traditional group. A, Movement measurements. B, Angle measurements. L, left; R, right. Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
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FIGURE 2. Measurements for VSP group. A, Movement measurements. B, Angle measurements. L, left; R, right; VSP, virtual surgical planning. Q9 Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
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FIGURE 3. Overall percentage of change of temporomandibular joint relations from pre- to postoperatively using traditional or VSP mandibQ10 ular reconstruction. L, left; R, right; VSP, virtual surgical planning. Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
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FIGURE 4. Percentages of ipsilateral and contralateral temporomandibular joint change after traditional or VSP mandibular reconstruction. A, Left-side temporomandibular joint changes after left-side mandibular reconstruction. B, Right-side temporomandibular joint changes after leftside mandibular reconstruction. (Fig 4 continued on next page.) Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
Patients who underwent left mandibular reconstruction exhibited statistically relevant changes in ipsilateral and contralateral TMJ positional and angular percentages of change (Fig 4). Patients who underwent left mandibular reconstruction showed a statistically significant percentage of change in the ipsilateral superior and anterior shifts (superior shift, 22 vs 10%; anterior shift, 32 vs 15%; P < .05). The ipsilateral condylar neck angle exhibited the greatest difference in percentage of change from pre- to postoperatively, when traditional and VSP mandibular reconstruction groups were evaluated (condylar neck angle, 72 vs 2.68%; P < .01; Fig 4A). The contralateral TMJ after left mandibular reconstruction showed a statistically significant difference in the condylar neck angle (71 vs 49%; P < .05) on the right
and the intercondylar neck angle (32 vs 6.7%; P < .05; Fig 4B). Patients who underwent right mandibular reconstruction showed statistically relevant differences in the percentage of change in pre- to postoperative ipsilateral and contralateral TMJ superior shifts. Ipsilateral and contralateral superior shift changes from pre- to postoperatively were 61.7 versus 14.7% (P < .05) and 45 versus 12.6% (P < .05), respectively (Fig 4C, D).
Discussion VSP is a critical tool in the reconstructive armamentarium. Given the digital manipulation and ability to quantitatively direct the operative plan, it is believed to enable improved precision and
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FIGURE 4 (cont’d). C, Right-side temporomandibular joint changes after right-side mandibular reconstruction. D, Left-side temporomandibular joint changes after right-side mandibular reconstruction. L, left; R, right; VSP, virtual surgical planning. Sawh-Martinez et al. TMJ Position After Virtual Reconstruction. J Oral Maxillofac Surg 2016.
predictability.18-20 Prior studies evaluating complex microvascular mandibular reconstruction have focused on the relations of the bony construct. No studies have yet evaluated the complex condylar position and its alteration after reconstruction using VSP. In the present study, the authors evaluated the positional and angular changes of various anatomic landmarks as they relate to the TMJ position preand postoperatively in patients who underwent mandibular reconstruction with or without VSP. VSP enhances the ability to create precise bony segments with 3D printed cutting guides that are specific to a planned resection defect. Prior studies have reported improved bony apposition and decreased operative times.17-19 Pre-bent plates allow for faster securing of bony segments and improved contact between osteotomy segments. With improved precision of fixating the fibular segments to the native mandible, less theoretical displacement can be achieved, thus preserving TMJ position and presumed function. The present data showed a decreased percentage of change in the mandibular position postoperatively when VSP was used. This could be attributable to
the ability to custom create cutting guides, precise osteotomies, and smaller bony gaps or interferences as described in prior studies.17-20 Of note, the greater stability of the condylar position with VSP for mandibular reconstruction was noted to occur at the ipsilateral and contralateral TMJs. Consistently large decreases in superior condylar displacement were noted when VSP was used. Although these data do not represent active functional data of the joint, the authors presume that greater positional stability will lead to preservation of preoperative function, although this was not tested. Given the serious overall morbidity with mandibular resection and reconstruction, higher-order functional outcomes are difficult to ascertain. Notable surgical outcomes of normative occlusion, placement of dental implants, speech, and swallow functions were attained in the 2 groups without statistical differences. Precise TMJ function and degree of rotation were not routinely measured preoperatively, precluding analysis. These data point to the added utility of VSP, which aides in the positioning of mandibular segments
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during reconstruction. Having cutting guides based on the surgical plan, the mandibular segments fit together with added precision intraoperatively, decreasing the need for manipulation of mandibular segments that can affect the movement of the TMJ. Prior studies have reported an increased reproducibility of spatial positioning of the mandibular segments during reconstruction.17-20 The effect of reconstruction on the anatomic position of the TMJ has not been explored previously but is a key component of postoperative patient functionality. In total TMJ reconstruction, the joint retains its function as a hinge but loses its ability for full translation. For mandibular segmental reconstruction, the condyle might be positioned out of its native joint. The presumption has been that the attached ligaments and joint capsule allow for maintenance of position; however, there can be disc displacement and postoperative ankylosis. These outcomes have been seldom evaluated, because there have been limited alternative methods to improve surgical accuracy before VSP. TMJ position is affected by the position and placement of segments in mandibular reconstruction. VSP can lead to increased precision in this reconstruction, preserving normative anatomic relations at the TMJ that can directly affect joint function. Long-term outcome studies of TMJ motion analysis are needed to evaluate whether there is improved clinical functionality. The present data showed comparable pre- and postoperative positions of the TMJ for traditional and VSP mandibular reconstructions. Evaluation of condyle movements showed differences in ipsilateral position in pre- and postoperative groups. VSP resulted in decreased superior and lateral shifts of the ipsilateral condyle and decreased changes in the condylar and condylar neck angles. This work shows that VSP can lead to increased precision in reconstruction, leading to preserved normative anatomic relations.
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2. Hidalgo DA: Fibula free flap: A new method of mandible reconstruction. Plast Reconstr Surg 84:71, 1989 3. Wolff KD, Ervens J, Herzog K, et al: Experience with the osteocutaneous fibula flap: An analysis of 24 consecutive reconstructions of composite mandibular defects. J Craniomaxillofac Surg 24:330, 1996 4. Urken ML, Weinberg H, Vickery C, et al: Oromandibular reconstruction using microvascular composite free flaps. Report of 71 cases and a new classification scheme for bony, soft-tissue, and neurologic defects. Arch Otolaryngol Head Neck Surg 117:733, 1991 5. Cordeiro PG, Hidalgo DA: Conceptual considerations in mandibular reconstruction. Clin Plast Surg 22:61, 1995 6. Wolford LM, Reiche-Fischel O, Mehra P: Changes in temporomandibular joint dysfunction after orthognathic surgery. J Oral Maxillofac Surg 61:655, 2003 7. Raveh J, Vuillemin T, Ladrach K, et al: Temporomandibular joint ankylosis: Surgical treatment and long-term results. J Oral Maxillofac Surg 47:900, 1989 8. Kaban LB, Perrott DH, Fisher K: A protocol for management of temporomandibular joint ankylosis. J Oral Maxillofac Surg 48: 1145, 1990 9. Chidzonga MM: Temporomandibular joint ankylosis: Review of thirty-two cases. Br J Oral Maxillofac Surg 37:123, 1999 10. Ciocca L, Mazzoni S, Fantini M, et al: CAD/CAM guided secondary mandibular reconstruction of a discontinuity defect after ablative cancer surgery. J Craniomaxillofac Surg 40:e511, 2012 11. Derand P, Hirsch JM: Virtual bending of mandibular reconstruction plates using a computer-aided design. J Oral Maxillofac Surg 67:1640, 2009 12. Gateno J, Teichgraeber JF, Aguilar E: Computer planning for distraction osteogenesis. Plast Reconstr Surg 105:873, 2000 13. Hassfeld S, Muhling J: Computer assisted oral and maxillofacial surgery—A review and an assessment of technology. Int J Oral Maxillofac Surg 30:2, 2001 14. Hsu SS, Gateno J, Bell RB, et al: Accuracy of a computer-aided surgical simulation protocol for orthognathic surgery: A prospective multicenter study. J Oral Maxillofac Surg 71:128, 2013 15. Hirsch DL, Garfein ES, Christensen AM, et al: Use of computeraided design and computer-aided manufacturing to produce orthognathically ideal surgical outcomes: A paradigm shift in head and neck reconstruction. J Oral Maxillofac Surg 67:2115, 2009 16. Tepper OM, Sorice S, Hershman GN, et al: Use of virtual 3-dimensional surgery in post-traumatic craniomaxillofacial reconstruction. J Oral Maxillofac Surg 69:733, 2011 17. Eckardt A, Swennen GR: Virtual planning of composite mandibular reconstruction with free fibula bone graft. J Craniofac Surg 16:1137, 2005 18. Metzler P, Geiger EJ, Alcon A, et al: Three-dimensional virtual surgery accuracy for free fibula mandibular reconstruction: Planned versus actual results. J Oral Maxillofac Surg 72:2601, 2014 19. Foley BD, Thayer WP, Honeybrook A, et al: Mandibular reconstruction using computer-aided design and computer-aided manufacturing: An analysis of surgical results. J Oral Maxillofac Surg 71:e111, 2013 20. Stirling Craig E, Yuhasz M, Shah A, et al: Simulated surgery and cutting guides enhance spatial positioning in free fibular mandibular reconstruction. Microsurgery 35:29, 2014
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