CANINE-MAnaging Mandibular Fractures in Dogs
CANINE-MAnaging Mandibular Fractures in Dogs
CANINE-MAnaging Mandibular Fractures in Dogs
5 May 1996
Managing Mandibular
FOCAL POINT
Fractures in Dogs
★ Each of the approaches to Rapperswil, Switzerland Noah’s Ark Pet Hospital
the management of canine Rensselaer, Indiana
Ulrich A. Goeggerle, DrMedVet
mandibular fractures has
Greg A. Inskeep, DVM
advantages and disadvantages;
Purdue University
the technique to be used will vary
from case to case. James P. Toombs, DVM, MS
KEY FACTS
■ Vehicular trauma—usually,
being hit by a car—is the most
I n dogs, the incidence of mandibular fractures is 1.5% to 2.5% of all frac-
tures.1 The most common causes of these fractures in dogs are vehicular
trauma, fights, unknown trauma, iatrogenic trauma, and gunshots. The
most frequently affected areas are the premolar, molar, and symphyseal regions
and the vertical ramus. The canines, the incisors, and the condylar and coro-
common cause of canine
mandibular fractures. noid regions are less commonly affected (Figure 1). Nearly 50% of dogs that
sustain mandibular fractures are younger than 1 year of age1 (see the box). This
■ Mandibular fractures constitute a article reviews the common types of mandibular fractures in dogs and discusses
small percentage of all fractures several management techniques.
in dogs (1.5% to 2.5%).
ANATOMY AND BIOMECHANICAL PRINCIPLES
■ The endotracheal tube is ideally Appropriate management of fractures of the mandible depends on a knowledge of
placed through a pharyngostomy the exact anatomy and the biomechanical principles of this dynamic structure (Fig-
opening in order to enable ure 2). The mandibular canal is a very important structure that contains the alveolar
optimum assessment of dental artery, vein, and nerve. It marks the border between the upper two thirds and the
occlusion. lower third of the mandibular body. Proper decision-making in fracture repair de-
pends on an appreciation of the tension side of the bone and the various forces that
■ Dental bonding, which is a act on it. The tension side of the mandible is on the alveolar margin (Figure 3).
relatively new technique, has
been successfully used to MANAGEMENT
manage various fractures in Anesthesia in Fracture Repair
several regions of the mandible. Because dental occlusion is used as a guide in fixation of most mandibular
fractures, normal placement of an endotracheal tube interferes with proper surgi-
cal technique. Placement of the tube through a pharyngostomy opening is rec-
ommended in all cases in which dental occlusion is used to assess functional posi-
tive or negative anatomic reduction of mandibular fractures.2 A recommended
technique for translocation of the endotracheal tube3 is illustrated in Figure 4.
Repair Techniques
Tape Muzzle
A tape muzzle is indicated for fractures with healthy soft tissue and high
Small Animal The Compendium May 1996
Interarcade Wiring
wiring are symphyseal fractures (if the incisors are in- Interarcade wiring can be used for simple, nondis-
tact and firm7) and simple transverse mandibular body placed fractures of the mandibular body and ramus10
fractures.3 Oblique and complicated fractures of the and even for severely comminuted fractures that
body of the mandible are contraindications. The tech- involve the vertical ramus. Other indications include
nique should be avoided if teeth next to the fracture those described for the tape muzzle technique. Signifi-
line are loose or broken. Short-duration injectable anes- cantly displaced fractures and fractures with bone loss
thetics (e.g., propofol) or gas anesthesia are appropriate are contraindications for interarcade wiring.
for this procedure. The wire is General anesthesia is necessary
tightened on the buccal side just to perform the technique. The
enough to maintain reduction3 last upper premolar (P4) and the
(Figure 7). If the wire is tight- first lower molar (M1) are iden-
ened too much, distraction of tified bilaterally. The gingiva
the ventral part of the fracture around these teeth is elevated
can result. If this occurs, addi- A subperiosteally on the lingual
tional interfragmentary wiring and buccal surfaces and retracted
will be necessary.9 so that the adjacent bone be-
The major advantage of this comes visible. Holes are drilled
technique is that there are no in the maxilla and mandible, in a
implants in the fractured region. D buccal-to-lingual direction, be-
In addition, the technique is in- Figure 4— Placement of an endotracheal tube tween the roots immediately ad-
expensive and easy to perform. through a pharyngostomy opening. (A) Palpation jacent to the body of the tooth.
Indications for this technique are of the piriform fossa through the mouth. (B) Skin The holes are drilled perpendic-
limited. It should only be used if incision over the piriform fossa. (C) Guiding ular to the tooth axis. Placement
the teeth next to the fracture line the endotracheal tube from the pharynx through of the wire is depicted in Figure
are firm and intact and if the re- the incision. (D) The endotracheal tube placed 9. The ends of the wire are
gion is easily accessible. through the pharyngostomy opening. (From Slat- twisted next to the hole in the
ter DJ: Textbook of Small Animal Surgery, ed 2. mandible. Normal occlusion is
Interfragmentary Wiring Philadelphia, WB Saunders Co, 1993, p 1921. obtained by holding the jaws
Reprinted with permission.)
Indications for interfragmen- manually together, and the final
Plate Fixation
Plate fixation is
Figure 5—Tape muzzle applied to a dog with a mandibular indicated in manag-
fracture. ing complex and bilat-
eral fractures of the
mandibular body 7
tightening of the wire is done. The twisted end is short- and fractures of the
ened and placed in the space between the two rows of ramus. Contraindica-
upper and lower teeth10 (Figure 9). If the wire is placed tions are infected Figure 7—Interdental wiring. (A)
correctly, direct pressure is applied only to the teeth; fractures and fractures Correct application of wire. (B)
bone necrosis thus is minimal. 10
with bone loss. Gen- Distraction of the ventral part of
the fracture line caused by exces-
The procedure is inexpensive, easy to maintain, and eral anesthesia is re-
10 sive wire tension. (From Slatter
well tolerated. Aspiration of ingesta is rare but may quired. For fractures DJ: Textbook of Small Animal
occur if the animal vomits. This is the major potential of the mandibular Surgery, ed 2. Philadelphia, WB
disadvantage of the technique. Stretching and breaking body, a ventral ap- Saunders Co, 1993, p 1915. Re-
of the wire 10 and sub- proach is performed.2 printed with permission.)
sequent loss of fracture For fractures in the
reduction is another po- region of the ramus, a
tential complication. lateral approach is preferred. Ideally, the plate is placed
next to the alveolar border of the mandibular body, which
Intramedullary is the tension side of this bone; however, plates are often
Pinning placed near the ventral border of the mandibular body to
Unilateral and bilateral avoid tooth roots and the mandibular canal. After reduc-
transverse or oblique tion of the fracture, the plate is contoured to the bone (the
fractures of the mandibu- most important step in this procedure). Placement of the
lar body (especially in the plate follows the general principles of plate fixation in oth-
area from PM2 to M111) er bones3,5 (Figure 11).
can be managed via in- An advantage of plate fixation is that the technique
tramedullary pinning. provides good rigidity,7 allowing unrestricted use of the
Contraindications are mandible immediately after surgery.7 Disadvantages are
comminuted fractures that the procedure is expensive and difficult to per-
and fractures with bone form. Direct contact of the implant with the fracture
Figure 6— Loop cerclage with
loss as well as fractures stainless steel. After placement of disturbs circulation to the healing bone. Because of the
rostral to the second pre- two hypodermic needles (1 and anatomy of the mandible, it is hard to place a bone
molar and caudal to the 2), a stainless-steel wire is inserted plate at the location that is biomechanically ideal.
first molar. General anes- using the needles as a guide. The
thesia is necessary to per- wire is twisted outside the skin. External Skeletal Fixation
form the procedure. The (From Brinker WO, Piermattei Indications for external skeletal fixation include
technique has been de- DL, Flo GS: Handbook of Small mandibular fractures that are complex,3 highly com-
scribed in the literature.11 Animal Orthopedics and Fracture minuted,3 or open3 and those that involve bone loss.12
The fact that intra- Treatment. Philadelphia, WB Generalized bone disease is a contraindication for this
medullary pinning is Saunders Co, 1990. Reprinted technique.13,14 Dogs with mandibular fractures have
with permission.)
relatively inexpensive been successfully treated via several external fixation
dog vomits, can also be avoided by good instruction of Textbook of Small Animal Surgery, ed 2. Philadelphia, WB
owners.6 Saunders Co, 1993, pp 1910–1921.
4. Withrow SJ: Taping of the mandible in treatment of man-
dibular fractures. JAAHA 11:27–31, 1981.
SUMMARY 5. Taylor RA: Mandibular fractures, in Bojrab MJ (ed): Cur-
Each of the techniques described here has advantages rent Techniques in Small Animal Surgery, ed 3. Philadelphia,
and disadvantages, and each has distinct indications. Lea & Febiger, 1990, pp 890–894.
The decision of which technique to use should be made 6. Wallace BJ, Kapatkin AS, Manfra Maretta S: Dental com-
on a case-by-case basis. Intramedullary pinning in posite for the fixation of mandibular fractures and luxations
in 11 cats and 6 dogs. Vet Surg 23:190–194, 1994.
mandibular fractures has numerous disadvantages and 7. Brinker WO, Piermattei DL, Flo GS: Fractures and disloca-
thus cannot be recommended. Dental bonding is a rel- tions of the upper and lower jaw, in Handbook of Small Ani-
atively new technique that has been successfully used mal Orthopedics and Fracture Treatment. Philadelphia, WB
to manage various fractures in several regions of the Saunders Co, 1990, pp 230–243.
mandible. We recommend this technique as a fairly easy 8. Hinko PJ: A method for reduction and fixation of symphy-
to perform, inexpensive, and effective method for man- seal fractures of the mandible. JAAHA 12:98–100, 1976.
9. Chambers JN: Principles of management of mandibular
aging mandibular fractures. With the exception of the fractures in the dog and cat. J Vet Orthop 2(2):26–36, 1981.
tape muzzle (a basic and commonly used technique), 10. Lantz GC: Interarcade wiring as a method of fixation for se-
this article has not described the procedures in detail. lected mandibular injuries. JAAHA 17:599–603, 1981.
11. Cechner PE: Malocclusion in the dog caused by intra-
medullary pin fixation of mandibular fractures: Two case re-
ports. JAAHA 16:79–85, 1980.
About the Authors 12. Greenwood KM, Creagh JR: Bi-phase external skeletal splint
Dr. Goeggerle is in private practice in a small animal clinic fixation of mandibular fractures in dogs. J Am Coll Vet Surg
in Rapperswil, Switzerland. Dr. Inskeep is affiliated with 9:128–134, 1980.
Noah’s Ark Pet Hospital in Rensselaer, Indiana. Dr. 13. Stampley AR, Lawrence D: Acrylic external fixation in the
treatment of complex mandibular fractures. Canine Pract
Toombs, who is a Diplomate of the American College of
18(6):15–19, 1993.
Veterinary Surgeons, is affiliated with the Department of 14. Weigl JP, Dorn AS, Chase DC, Jaffrey B: The use of the
Clinical Sciences, School of Veterinary Medicine, Purdue biphase external fixation splint for repair of canine mandibu-
University, West Lafayette, Indiana. lar fractures. JAAHA 17:547–554, 1981.
15. Toombs JP: Treatment of mandibular fractures with the
bi-phase external fixation splint. Proc 16th Annu Vet Surg
Forum:257–258, 1988.
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