Successful maxilla reimplantation after traumatic injury in a dog - Veterinary Medicine
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Successful maxilla reimplantation after traumatic injury in a dog
This clinician suggests that maxillectomy is not the only possible treatment choice in cases of severe facial injury and suggests criteria that may help you assess similar candidates for reconstruction.


VETERINARY MEDICINE


Surgical treatment


Figure 3: A dorsal intraoperative view showing the first steps of reconstruction, which consisted of placing bone sutures (0.6-mm cerclage wire) through paired holes in the severed rostral and caudal segments of the nasal bone. The arrows point to the entrance and exit of one wire. (Oral is to the left, aboral is to the right.)
During surgical exploration, the wound was considered clean-contaminated and was not associated with marked crushing injuries to the surrounding soft tissue. The bone edges seemed viable and were bleeding, and, although the rostral portion of the maxilla was pale and cold, suggesting severe compromise to the arterial blood supply, I decided to perform reimplantation with complete reconstruction of the face, instead of a rostral maxillectomy.


Figure 4: A dorsal intraoperative view of the reconstructive procedure showing that after preplacement of the cerclage wires, the wires (arrows) were tightened as the bone fragments were realigned.
After further copious lavage, the left maxillary canine tooth, which had been split longitudinally during the accident, was extracted. The first step of the reconstructive procedure involved securing the edges of the nasal and maxilla bones bilaterally. After the edges were approximated, paired 1-mm holes were drilled on both sides of the nasal bone, and six cerclage wires (0.6 mm) were preplaced. The edges of the nasal and maxilla bones were approximated to reduce the fracture, and the wires were tightened (Figures 3 & 4). The dorsal subcutaneous tissues and identifiable portions of the levator nasolabialis muscle were closed with 4-0 braided polyglactin 910 in an interrupted pattern. The skin was closed with 4-0 monofilament nylon in a simple interrupted pattern, and the patient was repositioned in dorsal recumbency to explore the oral cavity.


Figure 5: An oral intraoperative view showing advancement flap repair of an oronasal fistula caused by the left maxillary canine tooth extraction. The arrowhead points to the flap held by a stay suture. The arrows highlight the reapposition of the oral mucosa with simple continuous sutures.
The patient's upper lip was retracted dorsally. An oronasal fistula caused by the maxillary canine tooth extraction was closed with a local simple advancement flap raised from the normal adjacent gingival and buccal mucosa (Figure 5). Two 2-mm Kirschner wires (K wires) were then inserted through the mucosal surface dorsal to the first right and second left incisors into the incisive bones of the premaxilla and directed caudoventrally, emerging through the hard palate caudal to the fracture site (Figures 6). The soft palate was reconstructed with simple interrupted sutures using 4-0 monofilament polyglyconate. Two figure-of-eight 0.6-mm cerclage wires were placed to increase interfragmentary compression and stability (Figure 6). On the right side, the cerclage wire was placed around the canine tooth and the contralateral tip of the K wire, which was protruding from the hard palate (Figure 6). On the left side, the cerclage wire ran between the rostral and caudal tips of the K wire, passing just rostral to the maxillary canine alveolus. Defects in the mucosa and lips were closed with 4-0 polyglyconate in an interrupted or simple continuous pattern (Figure 5). The subcutaneous tissues and the skin of the lips were closed with 5-0 polyglactin 910 and 4-0 monofilament nylon, respectively. The soft tissue (skin) laceration on the antebrachium was lavaged with sterile saline solution, débrided, and closed with 4-0 polyglyconate in the subcutaneous tissue and 4-0 nylon in the skin in a simple interrupted pattern.


Figure 6: An oral intraoperative view after maxilla reimplantation. Note the converging K wires (arrows) entering the premaxilla and exiting the mucosal surface after crossing the hard palate caudal to the fracture site. The figure-of-eight tension band wires were anchored to the protruding tips of the K wires (arrowhead).
The dog's immediate postoperative appearance is shown in Figure 7. The tip of the nose slightly tilted upward from not bending the wires implanted into the premaxilla. Postoperatively, morphine (0.2 mg/kg subcutaneously every four hours) was administered for two and a half days, and cefazolin (30 mg/kg intravenously t.i.d.) and gentamicin sulfate (5 mg/kg subcutaneously once a day) were administered for six days. Because gentamicin can be nephrotoxic, a urine specific gravity and sediment and serum blood urea nitrogen and creatinine concentrations were monitored daily. No parenteral or enteral nutrition ports were required, because the dog was able to eat and drink on its own the day after surgery. The dog was fed a commercial canned dog food and was given water ad libitum. Oral hygiene was performed after each meal by applying 0.9% saline solution and an oral antiseptic (0.12% chlorhexidine gluconate) to the intraoral suture lines.


Figure 7: An immediate postoperative view. Note that the tip of the nose tilts slightly upward because of the unbent ends of the two K wires entering the premaxilla.
The dog was discharged seven days after surgery. The owner was instructed to feed the dog canned food for two weeks and to make a slow transition to dry food after 14 days. Dry food was allowed as of the third week after discharge. Oral hygiene was strongly advised, which involved flushing the oral cavity with 0.12% chlorhexidine after each meal (at least three times a day) for two weeks.

Follow-up


Figure 8: The patient one month after maxilla reconstruction. Note the depigmentation of the nose and upper left lip and the presence of a small skin ulcer on the upper left muzzle.
Ten days after surgery, the dog returned for suture removal. The owner reported that the dog was breathing with its mouth closed and had resumed normal activities on the farm. On physical examination, the tip of the nose appeared pale and hypopigmented, but the capillary refill time in the upper lip was nearly normal, and the gingiva and mucosal surfaces of the mouth were pink. A small oronasal fistula had formed because of wound dehiscence near the upper left canine alveolus. The skin sutures were removed, and I recommended surgical correction of the oronasal fistula. The patient was discharged with instructions regarding oral hygiene.


Figure 9: An oral view one month after maxilla reimplantation showing the exit points of the two K wires, the loss of the left tension band wire, and the presence of an oronasal fistula where the left upper canine tooth was extracted. Note the extensive depigmentation of the upper left lip.
Three weeks later, the patient returned for oronasal fistula correction and radiographic evaluation of maxillary bone healing. The radiographic examination showed adequate healing and no implant problems. The tip of the nose and the left upper lip were still hypopigmented, but the paleness had subsided. A small orocutaneous fistula had developed, which was communicating with the oronasal fistula (Figures 8-10). The oronasal fistula was surgically corrected by using a simple pediculate advancement flap with tension release, and all orthopedic implants were removed. The orocutaneous fistula was lavaged and allowed to heal by second intention. Twice-daily flushing with saline solution was recommended.


Figure 10: This view of the patient one month after facial reconstruction shows adequate dental occlusion. The arrow points to the contaminated oronasal fistula, a post­operative complication observed in this case.
On reexamination two months later, repigmentation of the lip and nose had occurred. The cutaneous fistula was closing by second intention (Figure 11). Overall, healing was considered good. The final cosmetic result, four months after surgery, is shown in Figure 12. A mild left upper lip elevation was present, resulting from scar contraction of the orocutaneous fistula.


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Source: VETERINARY MEDICINE,
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