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Paul C. Frake, MDDiv. of Otolaryngology - Head & Neck SurgeryThe George Washington Universitypfrake@gmail.com

Objective: To describe a novel technique for internal fixation of mandibular condyle fractures, as well as a new type of implant for the same. Also, to demonstrate surgical feasibility of this technique in a cadaver model.

Methods: A transoral endoscopic approach was used to access an osteotomized mandibular condyle in two human cadavers. Titanium intramedullary implants were placed endoscopically after reaming of the medullary space without the need for transbuccal puncture or facial incisions. Both pin and screw type implants were tested. The osteotomies were able to be reduced and rigidly fixed using the intramedullary implants.

Results: Both cadaveric mandibular condyles were successfully repaired with rigid intramedullary internal fixation without the use of external incisions. Both insertion of a peg type implant and screwing a threaded implant into the condylar head are possible. The inferior portion of the implant remains exposed and the ramus of the mandible can be manipulated into position on the implant using retraction at the sigmoid notch.

Conclusions: True total endoscopic repair of fractures of the mandibular condyle is possible by utilizing novel intramedullary titanium implants and a transoral endoscopic approach.

Feasibility of Endoscopic Intramedullary Fixation of Fractures oFeasibility of Endoscopic Intramedullary Fixation of Fractures of the Mandibular Condylef the Mandibular CondylePaul C. Frake, MD1; Joseph F. Goodman, MD1; Arjun Joshi, MD1

1Division of Otolaryngology – Head & Neck Surgery, The George Washington University, Washington, DC

Intramedullary fixation is a treatment concept which was popularized by orthopedic surgeons for the treatment of long bone fractures in the early and mid-20th century. In orthopedic practice it was noted that intramedullary fixation allowed for healing with greater ease of application and less muscular damage and periosteal stripping compared to plates and screws.10 Several years later, facial trauma surgeons began to describe the application of k-wire internal fixation of mandible fractures, including for fractures of the condyle.11

Early condylar intramedullary fixation required insertion of theimplant at the mandibular angle. The implant would then traverse the medullary space of the ramus and up to the condyle.11 Lag screw fixation in this manner has also been attempted and shown favorable mechanical characteristics in comparison to traditional miniplates.12 However, this full-length intramedullary technique requires one or more transcervical or transfacial incision and is not widely used in clinical practice today.

With the introduction of endoscopic techniques to facial trauma surgery, a short-segment intramedullary implant may allow for rigid fixation of these condylar fractures without the need for transcutaneous incisions and their associated morbidity. This preliminary feasibility study demonstrates that in human cadavers the technique of total endoscopic open reduction and internal fixation of fractures of the mandibular condyle is possible when utilizing this type of novel short-segment implant. Further study will be necessary to determine the material properties of this type of intramedullary fixation and evaluate its potential for clinical utility.

The cadaveric specimens were placed in the appropriate anatomical position for transoral endoscopic surgery. An incision was made in the buccal mucosa at the level of the mandibular ramus with a scalpel. Blunt dissection was carried down to the mandibular bone and the endoscope was introduced. A Freer elevator was used to dissect the soft tissue away from the fracture site. Once this was accomplished the free end of the condylar fragment was visualized. It is manipulated into a position lateral to the mandibular ramus using a hooked probe instrument (Figure 6).

Next, the medullary space of the condyle is reamed using gentle finger twisting of a free surgical drill bit (Figure 7). The implant is then introduced and can either be slid or screwed (depending on the design of the implant) into the medullary space of the condyle (Figure 8). The condyle with segment of the implant still exposed is placed lateral to the ramus (Figure 9). A double-angled hook retractor is then placed over the sigmoid notch and downward retraction is placed on the mandible. Once the ramus is below the level of the protruding implant its medullary space is maneuvered over the implant and retraction is released. Gentle superiorly directed pressure can be applied to the angle of the mandible using the surgeons hand to further seat the implant within the distal medullary space and reduction is complete (Figure 10). The transoral incision is then closed in the standard fashion.

True total endoscopic repair of fractures of the mandibular condyle is possible by utilizing short-segment intramedullary titanium implants and a transoral endoscopic approach.

Adequate surgical exposure, fracture site manipulation, implant insertion, and fracture reduction were demonstrated in this cadaveric model.

The treatment of mandibular condyle fractures has been a topic of great debate and research over the last century. Because these fractures can cause significant morbidity if left untreated, facial trauma surgeons have attempted to apply many different operative techniques and implant designs in order to prevent morbidity including malocclusion, facial asymmetry, and mandibular hypofunction or dysfunction.1 In their review of the biomechanical mechanisms of condylar function in the setting of a fracture, Ellis and Throckmorton describe biomechanical adaptations to condylar fractures and discuss how, based on the biology of the individual fracture, certain fractures will functionally heal without intervention and others will not despite the most careful surgical treatment.2

When we consider mandibular condyle fractures which do require surgical intervention, there is continued debate over whether “open” or “closed” treatment is best.3,4 “Closed” treatments involve rigid or elastic maxillomandibular fixation with or without reduction of the fracture (Figures 1,2). “Open” treatments include a variety of surgical approaches utilizing incisions through the face, neck, or oral mucosa (Figures 3-5). These open approaches improve anatomical reduction of condylar fractures4 but they add a dimension of iatrogenic morbidity to the treatment of these complex patients.

The most common iatrogenic complications of surgical treatment of mandibular condyle fractures include paresis or paralysis of the facial nerve or its branches. This has been reported to occur in approximately 12-17% of patients, although most recover function in the long-term.5,6 Hypertrophic scars on the face or neck are another concern, occurring in 7.5% of cases, and rarely salivary fistula is encountered.6

In an effort to reduce iatrogenic morbidity, surgeons have begun to employ transoral endoscopic techniques to access condylar and subcondylar fractures. This allows for anatomic reduction of the fracture7 but application of currently available plates and screws is difficult and regularly requires the use of a transfacial puncture incision (which reintroduces the risk of injury to the facial nerve, hypertrophic scarring, and salivary fistula). Further problems regarding the strength and stability of miniplate implants in treatment of condylar fractures have also been encountered. In a detailed biomechanical evaluation of the stresses on a miniplate applied to a condylar fracture, Wagner et al have demonstrated that bite force loading on a titanium miniplate can exceed the static yield limit of the plate which leads to mechanical failure (bending or breaking) of the implant.8 This phenomenon of miniplate mechanical failure in the form of breaking or bending has been encountered clinically in excess of 20% of cases.8,9

The optimal implant for use with a transoral endoscopic technique for fixation of these fractures would have greater mechanical strength than miniplates and would not require a transfacial puncture or incision for its application. It is in this setting, that we present a novel intramedullary implant design and surgical technique for reduction and fixation of fractures of the mandibular condyle.

INTRODUCTION

METHODS AND MATERIALS 1) Ellis E. Complications of mandibular condyle fractures. Int J Oral Maxillofac Surg. 1998;27:255-257.2) Ellis E, Throckmorton GS. Treatment of mandibular condylar process fractures: biological considerations. J Oral Maxillofac Surg. 2005;63:115-134.3) Nussbaum ML, Laskin DM, Best AM. Closed versus open reduction of mandibular condylar fractures in adults: a meta-analysis. J Oral Maxillofac Surg. 2008;66:1087-1092.4) Danda AK, Muthusekhar MR, Narayanan V, Baig MF, Siddareddi A. Open versus closed treatment of unilateral subcondylar and condylar neck fractures: a prospective, randomized clinical study. J Oral Maxillofac Surg. 2010;68:1238-1241.5) Gerbino G, Boffano P, Tosco P, Berrone S. Long-term clinical and radiological outcomes for the surgical treatment of mandibular condyle fractures. J Oral Maxillofac Surg. 2009;67:1009-1014.6) Ellis E, McFadden D, Simon P, Throckmorton G. Surgical complications with open treatment of mandibular condylar process fractures. J Oral Maxillofac Surg. 2000;58:950-958.7) Schoen R, Fakler O, Metzger MC, Weyer N, Schmelzeisen R. Preliminary functional results of endoscope-assisted transoral treatment of displaced bilateral condylar mandible fractures. Int J Oral Maxillofac Surg. 2008;37:111-116.8) Wagner A, Krach W, Schicho K, Undt G, Ploder O, Ewers R. A 3-dimensional finite-element analysis investigating the biomechanical behavior of the mandible and plate osteosynthesis in cases of fractures of the condylar process. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;94:678-686.9) Hammer B, Schier P, Prein J. Osteosynthesis of condylar neck fractures: A review of 30 patients. Br J Oral Maxillofac Surg. 1997;35:288-291.10) Küntscher G. The intramedullary nailing of fractures. Clin Orthop. 1968;60:5-12.11) Stephenson KI, Graham WC. The use of the Kirschner pin in fractures of the mandibular condyle. Plast Reconstr Surg. 1952;10:19-22.12) Tominaga K, Habu M, Khanal A, Mimori Y, Yoshioka I, Fukuda J. Biomechanical evaluation of different types of rigid internal fixation techniques for subcondylar fractures. J Oral Maxillofac Surg. 2006;6:1510-1516.

CONCLUSIONS

DISCUSSION

REFERENCES

Figures 1&2: Pre and post-operative CT of a patient after closed reduction and MMF. Occlusion has been restored but the condyle is not reduced.

Figure 3-5: Preoperative CT, intraoperative photo, and postoperative CT oftranscutaneous ORIF of a mandibular condyle fracture with miniplate application.

ABSTRACT

CONTACT

All steps of the surgical procedure were successfully applied inboth of the cadaveric specimens. Zero and thirty degree endoscopes provided excellent visualization of the fracture site. The free condylar fragment was readily positioned lateral to the ramus. Gentle hand twisting of a drill bit was adequate to remove the contents of the medullary space without removal of adjacent cortical bone. The implant was able to be inserted or screwed into position into the condylar fragment. A retractor with a 90o bend followed by a right or left hook was required to securely retract the sigmoid notch inferiorly. This was accomplished and upon release of retraction the implant partially seated into the medullary space of the ramus. Depending on the tightness of fit within this medullary space, a varying degree of superiorly-directed gentle pressure was applied at the angle of the mandible to complete the reduction and application of the implant.

RESULTS

Figure 6: Endoscopic view and schematic drawing of position of the condyle lateral to the ramus.

DisclosurePaul Frake MD has independently filed for a United States utility patent related to the material in this presentation. There is no commercial involvement.

FundingThis study was supported by a trauma research grant from Arbeitsgemeinschaft für Osteosynthesefragen (AO) North America.

Figure 7: Endoscopic view and schematic drawing of reaming of the medullary space.

Figure 8: Endoscopic view and schematic drawing of placement of the intramedullary implant.

Figure 9: Endoscopic view and schematic drawing of the exposed implant during inferior retraction.

Figure 10: Endoscopic view and schematic drawing of fracture reduction utilizing the IM implant