Use of internal splinting to realign a noncompliant sternum in a cat with pectus excavatum

Marije Risselada Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.

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Hilde de Rooster Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.

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Tiziana Liuti Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.

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Ingeborgh Polis Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.

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Henri van Bree Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.

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DOI:
https://doi.org/10.2460/javma.228.7.1047
Volume/Issue:
Volume 228: Issue 7
Online Publication Date:
01 Apr 2006
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Abstract

Case Description—A 5.5-month-old female domestic longhair cat was examined because of dorsal deviation of the caudal aspect of the sternum and progressively worsening dyspnea during play activities.

Clinical Findings—A diagnosis of pectus excavatum was made clinically and confirmed radiographically. The cardiac silhouette was shifted into the right hemithorax. The vertebral index (VI) and frontosagittal index (FSI), which are radiographic indices used to grade the extent of the deformity, were 5.2 and 3.0, respectively. Minimum thoracic height was 13 mm at this time.

Treatment and Outcome—The sternal malposition was corrected during surgery; for stabilization, an internal splint was provided by use of a plate that was applied to the ventral side of the sternum. Radiographic indices improved until day 85; at that time, an increase in the distance between plate and sternum was detected, and plate removal was advised. The radiographic indices improved again after plate removal. At 310 days after surgery, VI was 9.6, FSI was 1.6, and minimum thoracic height was 34 mm. No dyspnea was evident during physical examination.

Clinical Relevance—Results of treatment suggest that this technique may be useful as an alternative surgical option for cats with pectus excavatum that have a noncompliant sternum.

Abstract

Case Description—A 5.5-month-old female domestic longhair cat was examined because of dorsal deviation of the caudal aspect of the sternum and progressively worsening dyspnea during play activities.

Clinical Findings—A diagnosis of pectus excavatum was made clinically and confirmed radiographically. The cardiac silhouette was shifted into the right hemithorax. The vertebral index (VI) and frontosagittal index (FSI), which are radiographic indices used to grade the extent of the deformity, were 5.2 and 3.0, respectively. Minimum thoracic height was 13 mm at this time.

Treatment and Outcome—The sternal malposition was corrected during surgery; for stabilization, an internal splint was provided by use of a plate that was applied to the ventral side of the sternum. Radiographic indices improved until day 85; at that time, an increase in the distance between plate and sternum was detected, and plate removal was advised. The radiographic indices improved again after plate removal. At 310 days after surgery, VI was 9.6, FSI was 1.6, and minimum thoracic height was 34 mm. No dyspnea was evident during physical examination.

Clinical Relevance—Results of treatment suggest that this technique may be useful as an alternative surgical option for cats with pectus excavatum that have a noncompliant sternum.

A5.5-month-old 2.5-kg (5.5-lb) sexually intact female domestic longhair cat was evaluated at the Small Animal Clinic of Ghent University because of a dorsal deviation of the caudal aspect of the sternum. The sternal deviation had been present when the current owner adopted the cat a month earlier. When playing, the cat became dyspneic, and the severity of the respiratory compromise was progressively increasing.

On physical examination, the caudal part of the sternum was severely displaced dorsally, and the cranial portion of the abdomen was protruding ventrocranially from the depression. The sternum felt rigid and was not pliable. Bilateral dorsal deviation of the caudal 4 ribs was easily detected via palpation.

The cat was not dyspneic at the time of initial evaluation. Via thoracic auscultation, cardiac sounds were audible on the right side but not the left side. No cardiac murmur or respiratory abnormalities were detected dur ing auscultation. Routine clinicopathologic analyses did not reveal any abnormalities, and results of blood tests for FIV antibody and FeLV antigen were negative.

A diagnosis of PE (or funnel chest) with a marked dorsal deviation of the caudal aspect of the sternum was made. To evaluate the severity of the malformation and additional problems involving the intrathoracic structures, standard lateral and ventrodorsal thoracic radiography was performed (Figure 1). On the left lateral radiographic view, marked dorsal displacement of the last 3 sternebrae was evident. There was mineralization of the rib cartilages involved in the deformity. The angle made by the xyphoid process and the ventral portion of the rib cage was 8°. The caudal thoracic portion of the trachea and the carina were displaced dorsally. On the ventrodorsal radiographic view, the cardiac silhouette was shifted into the right hemithorax. To determine the severity of the deformity, the VI and FSI were determined as described previously.1–3 Briefly, the VI is the ratio between the distance from the center of the dorsal surface of the 10th vertebral body to the nearest point on the sternum and the height of the 10th vertebral body at the same point. The FSI is the ratio between the width of the chest at the 10th vertebral body and the distance from the ventral surface of the 10th vertebral body to the nearest point on the sternum. The VI was determined as 5.2 (reference range, 12.6 to 18.8) and the FSI as 3.0 (reference range, 0.7 to 1.3); the deformity was classified as moderate to severe (Table 1). At the point of MinTH, the distance between the ventral surface of the vertebral body and the dorsal surface of the sternum (nearest point) was measured on the lateral radiographic view (13 mm).

Figure 1
Figure 1

Left lateral radiographic view of the thorax of a 5.5-month-old cat with dorsal deviation of the caudal portion of the sternum. Notice the marked dorsal displacement of the last 3 sternebrae. The angle between the xyphoid process and the ventral portion of the rib cage is 8°. The caudal aspect of the thoracic portion of the trachea and the carina are displaced dorsally.

Citation: Journal of the American Veterinary Medical Association 228, 7; 10.2460/javma.228.7.1047

Table 1—

Radiographic indices and measurements in a cat with pectus excavatum before and at intervals after surgery.
Time pointVI*FSI†MinTH‡ (mm)
Before surgery5.23.013
Days after surgery
05.82.618
16.62.422
86.62.422
147.41.922
278.01.922
679.01.727
858.61.827
1098.61.828
3109.61.634

Reference range for VI in cats, 12.6 to 18.8.1

Reference range for FSI in cats, 0.7 to 1.3.1

Measured on lateral thoracic radiographs.

As the respiratory signs progressively worsened, the cat was scheduled for corrective surgery. Because this cat was older than those in previous reports1,2,4–6 of cats that underwent PE correction, we opted for a surgical corrective procedure instead of application of an external splint. We planned to realign the caudal part of the sternum with the cranial, nondeformed part and stabilize the 2 parts with a plate.

After premedication with xylazine (1 mg/kg [0.45 mg/lb], IM) and carprofen (2 mg/kg [0.91 mg/lb], IV), anesthesia was induced with propofol (4 mg/kg [1.8 mg/lb], IV). Perioperative IV fluid therapy consisted of lactated Ringer's solution (10 mL/kg/h [4.5 mL/lb/h]). Anesthesia was maintained with isoflurane in oxygen administered to effect. A volume-controlled ventilator was used to provide controlled ventilation. Perioperative analgesia was provided via constant rate infusion of fentanyl (5 μg/kg/h [2.3 μg/lb/h]). At anesthetic induction and at 120 minutes after the incision, cefazolin (20 mg/kg [9.1 mg/lb]) was administered IV.

The cat was positioned in dorsal recumbency, and both the ventral aspect of the thorax and the abdomen were prepared aseptically for surgery. A midline skin incision was made that extended from the manubrium of the sternum to 2 cm cranial to the umbilicus. The abdomen was entered through the linea alba, and the incision was extended cranially to the last ribs on either side of the xyphoid process, leaving the process itself intact. The attachment of the falciform fat was incised on the left side, and its attachment to the muscular sternal part of the diaphragm was bluntly elevated. A small incision was made in this part of the diaphragm (approx 5 mm dorsal to the sternum), and the xyphoid process was retracted ventrally to increase exposure. This incision was sharply extended bilaterally (by use of Metzenbaum scissors) parallel to the costal arch to allow observation of the intrathoracic structures. No soft tissue attachment to the sternum was palpated intrathoracically. The heart was in the right hemithorax. Subjectively, the tip of the xyphoid process was at the same height as the caudal vena cava. Because of its rigidity, the sternum could not be pulled into a normal position.

The deep pectoral muscles were sharply incised bilaterally at their sternal attachments from the second sternebra to their caudal margin and then retracted laterally. This allowed exposure of the site of sternal deviation (the chondral junction between the fourth and fifth sternebra) and placement of the plate after correction of the deformity. At the fourth intersternebral junction, a No. 15 blade was used to remove the cartilage in a wedge shape with the base of the wedge positioned ventrally (Figure 2). Intrathoracic structures were protected manually from inadvertent penetration. The external abdominal oblique muscles were bluntly elevated bilaterally to increase exposure of the ribs. The site of bowing or maximal deformity of each of the fifth to eighth ribs was determined by digital palpation. At each deformity, external and internal intercostal muscles were elevated off the rib to allow placement of a rongeur. A small section of rib (1 to 2 mm) was removed by use of an angled Cicherelli rongeur, without evidence of penetration of the pleura as determined by digital palpation during and after costectomy. The periosteum at the costectomy site was deliberately kept intact to prevent development of intrathoracic adhesions and protrusion of the segment ends at each side of the costectomy into the thorax. After the costectomies, the caudal 3 sternebrae could be aligned with the cranial sternebrae to alleviate the malposition.

Figure 2
Figure 2

Schematic illustrations of the surgical intervention performed in a cat with PE. A—Transverse view. For the fifth through eighth ribs, the site of ostectomy was at the point of maximal deformation. The inner periosteum was left intact. In this panel, the left image represents the thoracic cavity prior to the surgery, and the right image represents the thoracic cavity after surgical correction has been performed. B—Lateral view. A chondrectomy was performed between the fourth and fifth sternebrae (upper image) after which the sternum was aligned and stabilized by use of a plate that was placed on the ventral surface of the sternum (lower image).

Citation: Journal of the American Veterinary Medical Association 228, 7; 10.2460/javma.228.7.1047

A 2-mm veterinary platea was cut to a length that covered the entire sternum (including 20 holes) and was contoured at the rostral end to accommodate the normal dorsal deviation of the cranial portion of the sternum. By use of 2-0 polydioxanone suture material, sutures were preplaced around sternebrae and ribs and through plate holes. Placement of the plate was evaluated for near-complete coverage of the xyphoid process and good apposition cranially, and the sutures were tied; several additional sutures were placed. A 1-mm-wide rim of the caudal end of the xyphoid process was left uncovered by the plate to protect the intra-abdominal structures.

A pneumothorax catheter was placed through a separate skin incision positioned parallel to the abdominal incision on the right side. The catheter was tunneled intra-abdominally through the incision in the diaphragm into the right hemithorax. The heart at this time was in the midportion of the thorax.

The diaphragmatic incision was closed in a simple continuous pattern with 2-0 polydioxanone suture; no tension of the diaphragm on the xyphoid process was detected. The abdominal wall was closed in a simple continuous pattern with 2-0 polydioxanone while ensuring that the plate remained outside the abdominal wall at the cranial aspect of the incision. By use of 2-0 polydioxanone suture material, the latissimus dorsi muscles were reattached to the underlying tissues with simple interrupted sutures, and the left and right pectoral muscles were sutured to one another and to the underlying tissues superficial to the plate. The thoracostomy tube was attached routinely, and 10 mL of air was evacuated from the thorax after routine closure of the subcutis and skin. Radiographs were obtained immediately after surgery; improvement in indices was evident (VI, 5.8; FSI, 2.6). The MinTH had increased from 13 to 18 mm. Bupivacaine diluted in saline (0.9% NaCl) solution was administered intrathoracically through the thoracostomy tube (1 mg/kg) immediately after surgery. Intravenous fluid therapy (lactated Ringer's solution) was continued at a maintenance rate of 6.66 mL/h. Methadone (0.1 mg/kg [0.045 mg/lb]) was given IV and repeated every 4 hours for the first 12 hours after surgery. Additional postoperative analgesia was provided with a transdermal fentanyl patch (25 μg/h) placed on the left hind limb for 3 days and carprofen (2 mg/kg, SC) once daily for 2 days. During the first 24 hours after surgery, 23.5 mL of a serohemorrhagic fluid was evacuated from the thoracic cavity. Cefazolin (20 mg/kg) was administered IV every 8 hours.

On the first day after surgery (day 1), the cat was bright and alert. The cat ate, and IV fluid therapy was discontinued. Heart sounds could be auscultated bilaterally, although they were still heard more clearly on the right side. Antimicrobial treatment was switched to cephalexin (20 mg/kg PO, twice daily for 48 hours), and methadone administration was discontinued. From 24 to 48 hours after surgery, 4 mL of a serous fluid was aspirated from the thoracic cavity. The thoracostomy tube was removed 48 hours after surgery. No subcutaneous emphysema was detected at any time.

On day 1 after surgery, the previously described dorsal displacement of the caudal portion of the sternum was decreased on the left lateral radiographic view (the angle between the xyphoid and the ventral portion of the rib cage was now 5°; Figure 3). The caudal portion of the thoracic trachea and the carina were still displaced dorsally. Mild pleural effusion was present, as evidenced by blurring of the ventral border of the heart and the caudal lung lobes on the radiographic images. On day 1, MinTH was 22 mm. On the ventrodorsal radiographic view, the cardiac silhouette was still shifted into the right hemithorax.

Radiographic evaluation was performed at 8, 14, 27, 67, 85, 109, and 310 days after surgery. From day 1 to day 67, there was a progressive increase in VI (from 6.6 to 9.0) and a decrease in FSI (from 2.4 to 1.7; Table 1). Additionally, MinTH increased from 22 to 27 mm. Prior to evaluation at day 85, the owner reported that the cat was reluctant to play and had increased respiratory effort after playing. The cat weighed 3.65 kg (8.03 lb). When radiography was performed on day 85, the indices indicated that the cat's condition had worsened; the distance between the sternum and plate had increased both cranially and caudally, indicating that the sutures were loosening, undergoing absorption, or cutting through the sternum. At this point, the decision was made to remove the plate; the surgery was to be combined with elective ovariohysterectomy.

The procedures were performed on day 91 after the initial surgery. The anesthetic and monitoring protocols were similar to those used for the first anesthetic period; at induction of anesthesia, carprofen (2 mg/kg, SC) was administered. The approach was performed through the same incision as the first surgery. The plate was embedded in fibrous tissue that also had filled the plate holes. No suture remnants were found. After plate removal, the sternum felt rigid on palpation and subjectively did not deviate dorsally. Ovariohysterectomy and closure of the incision were performed routinely. Postoperative analgesia was provided by administration of methadone (0.1 mg/kg, IM) at discontinuation of anesthesia and administration of carprofen (2 mg/kg, SC) the following morning. Antimicrobial treatment was discontinued after recovery from anesthesia.

Figure 3
Figure 3

Left lateral radiographic view of the thorax of the cat in Figure 1 three days after surgery to correct the deviation of the sternum. Notice that dorsal displacement of the caudal portion of the sternum is reduced (the angle between the xyphoid and the ventral portion of the rib cage is now 5°). The caudal aspect of the thoracic portion of the trachea and the carina are still displaced dorsally. The ventral border of the heart and the caudal lung lobes are blurred in the image because of mild pleural effusion. A plate has been placed on the ventral surface of the sternum, extending from the caudal midportion of the first sternebra to the ventral portion of the seventh sternebra.

Citation: Journal of the American Veterinary Medical Association 228, 7; 10.2460/javma.228.7.1047

Figure 4
Figure 4

Left lateral radiographic view of the thorax of the cat in Figure 1 obtained at an evaluation 310 days after surgery to correct the deviation of the sternum. Notice that the caudal sternebrae are still deviated dorsally (angle 3°) but that the thoracic height is increased, compared with radiographic findings before surgery. The intersternebral space between the fourth and fifth sternebrae is collapsed, and the intersternebral space between the fifth and the sixth sternebrae is narrowed.

Citation: Journal of the American Veterinary Medical Association 228, 7; 10.2460/javma.228.7.1047

At subsequent follow-up evaluations (days 109 and 310), the owner reported that the cat had no dyspnea and was able to play normally with other cats in the household. Clinically, the cat was bright and alert. On thoracic auscultation, breath sounds were normal; heart sounds were easily heard on the right side, but not on the left side, presumably because of right-sided displacement of the heart. Radiographically, the caudal sternebrae were still deviated dorsally (angle of 3°) on the left lateral view, but the thoracic height was increased, compared with preoperative findings. The intersternebral space between the fourth and the fifth sternebrae was collapsed, and the intersternebral space between the fifth and sixth sternebrae was narrowed (Figure 4). On the ventrodorsal radiographic view, the cardiac silhouette was still predominantly located in the right hemithorax. At days 109 and 310 after surgery, VI was 8.6 and 9.6, respectively, and FSI was 1.8 and 1.6, respectively. This indicated that the progressive changes in these indices had stabilized in the period after plate removal; in fact, the indices even had improved in the longer-term follow-up period, although they did not normalize. At 109 and 310 days after surgery, MinTH measurements were 28 and 34 mm, respectively, and the cat's weight was 3.8 kg (8.36 lb) and 5.0 kg (11 lb), respectively.

Discussion

Pectus excavatum or funnel chest is either the dorsal deviation of the caudal part of the sternum or a dorsoventral flattening of the entire thorax. The disease and its management in cats and dogs have been previously described.1–10 However, the etiology still remains poorly understood. The presence of shortened bands of muscle in the diaphragm has been described as a possible cause.11 In the cat of this report, no abnormalities in the diaphragm or thorax were detected via macroscopic inspection.

In human medicine, several indices are used to grade the severity of the sternal malformation; the pectus index (or pectus severity index) is most commonly used.12–15 The measurements for this index are usually obtained from computed tomographic images. The index is calculated by dividing the inner width of the thoracic cavity at its widest point by the distance from posterior surface of the sternum to the anterior surface of the vertebral column at the same point. In veterinary medicine, the human FSI and VI systems have been adapted for cats and dogs to allow grading of the deformity. Both reference values and grades of severity of PE have been described.2 The malformation in the cat of this report was classified as moderate to severe by use of the FSI and VI values. In several reported cases,2,5,8 a conservative approach was adopted, especially for older animals. For the cat of the present report, surgical correction appeared to be warranted because the cat had clinical signs of dyspnea that were progressive in severity in addition to severely abnormal FSI and VI scores (3.0 and 5.2, respectively).

The distance between the ventral surface of the vertebral body and dorsal surface of the sternum at the point of MinTH was also measured in the cat; MinTH was identified at the level of the eighth thoracic vertebra. We chose to assess this variable because the measurements for the previously described indices were performed at the 10th thoracic vertebra, which did not correspond to the site of maximal deviation in this cat. Measurements of MinTH revealed a progressive increase in thoracic height after surgery (from 13 mm before surgery to 34 mm at 310 days after surgery).

To our knowledge, in all but 3 reported cases, management of PE in cats and dogs has consisted of placement of percutaneous circumsternal sutures and an external splint.1,2,4,6 Presently, this is the treatment of choice in young animals with a compliant, nonossified sternum. The goal of this treatment is to pull the sternum outward and maintain this position while the sternum matures and becomes noncompliant in the corrected position. In most reports1,2,4–6 of animals with PE that were managed with application of an external splint, the animals were younger than the cat of this report. We had concerns about the rigidity of the sternum and ribs and the amount of traction and time required to correct the deformity.2 Similar reservations have been made previously, and several authors have recommended against the use of an external splint with percutaneous sutures in a mature animal that has a noncompliant sternum.3,16 Therefore, the decision was made to use a surgical approach to correct the deformity in the cat of this report. We are aware of only 3 reports3,5,10 of use of a surgical procedure to correct PE in animals. In 1 report,7 total resection of the sternum and its associated cartilages was performed in a cat. The use of sternectomy with good results has also been reported in 3 dogs with sternal osteomyelitis.17 Because the rib cartilages of the cat of this report were visibly mineralized on radiographs and markedly dorsally deviated, it appeared that leaving these portions of the affected ribs intact would possibly cause injury to the intrathoracic organs. Conversely, if those portions of the affected ribs were resected, a ventral defect extending the length of 3 sternebrae and width of the entire thoracic cavity would have been created, and the heart would be positioned directly over this defect. Therefore, reconstruction of this defect would have been required; 1 option would have been to use an implant, but the use of prosthetic material to fill a defect does not provide any physiologic benefit, and the material often migrates when used for PE correction surgery in humans.12 In the cat of this report, we considered the use of nonabsorbable synthetic mesh as an implant. However, this would not have provided support and might even bulge inward as the ribs returned to their preoperative position. Addition of a rigid material to the splint to keep the ribs in an outward position was considered, but we did not feel comfortable pursuing this type of splint construction. The ribs could have been sutured directly to one another, as performed in dogs undergoing sternal ostectomy,17 but this would have severely decreased intrathoracic volume and was not considered a valid option in this cat.

In another report,5 a 2-cm incision and wedge ostectomy were performed in a kitten, after which an external splint was applied. This procedure could have been an option in the cat of this report, but splint application was expected to be necessary for a long period, and the incidence of external splint-related problems, such as moist dermatitis and inflammation around suture tracts, increases as the duration of application increases. Additionally, we believed that the force needed to maintain alignment and correct the noncompliant sternum in this cat would be higher than that required in the kitten of the previous report, which would necessitate the use of a more stable internal splint. In a recent report10 of a 5-month-old cat, a combination of a surgical approach to the sternum with placement of a longitudinal trans-sternebral pin after realignment of the sternebrae and application of an external splint was described. In the cat of this report, the deformity was comparatively more severe (VI, 5.2 and FSI, 3.0 vs VI, 8.0 and FSI, 2.0510), and the technique used by those authors might not have been successful. Therefore, we opted for a more invasive surgical procedure, involving a sternal wedge chondrectomy, bilateral costal ostectomies, and plate stabilization.

Prior to designing a surgical approach, we performed a review of recent human medical literature to evaluate methods for stabilizing the sternum following correction of the deformity. Several procedures have been described with specific indications and complications. The use of an external splint has been largely abandoned in favor of internal fixation because of fewer complications and maximal correction.12 In the Nuss procedure15 (a minimally invasive technique for repair of PE), no cartilage is removed. A preformed convex steel bar is used as an internal splint. This procedure was developed for young children (< 5 years old) because of recurrence of the deformity in 1 or 2 more cranial intersternebral cartilages and concerns of interference with rib growth plates after techniques that involve resection.12 In a modified Nuss procedure,15 thoracoscopic guidance is used because complications involving cardiac perforation were reported after the procedure was performed blindly.18 Use of this procedure in older patients (> 11 years old) has less favorable results because the chest is less malleable.15

In the highly modified Ravitch repair, the deformed cartilage in the ribs and at the sternal attachment is removed and the structures of the ribcage are reattached. An anterior wedge osteotomy is made in the sternum, and the posterior sternal table is fractured but not displaced. The reconstruction is supported with internal fixation involving a retrosternal support bar.12 The most recent modification is a less invasive procedure than the original method.12,14,19 Procedures based on the Ravitch repair method are used in patients that are at least 8 years old or preferably in their early adolescent growth years.12 In the most recent modification of the Ravitch repair, minimal cartilage resection is used14; short sections of cartilage are resected laterally and medially from each of the deformed ribs, the cartilages are resutured to the sternum medially and to the ribs laterally, and a thin retrosternal stainless steel support bar is placed intrathoracically.14 In the cat of this report, we opted to splint the sternum itself instead of placing an intrathoracic bar. To be able to correct the deformity of the sternum, ostectomies of the deformed ribs were performed at the point of maximal deformation, leaving all the surrounding soft tissues including the medial periosteum and pleura intact to act as a splint and protect intrathoracic structures. This obviated the necessity of suturing the ribs, which we wanted to avoid because of the small diameter of the ribs.

The decision to incise the diaphragm was made to enable evaluation of the thoracic cavity for adhesions to the sternum that might have caused the deformity; guide the sutures digitally during placement to avoid penetration of intrathoracic structures; and avoid creating a situation conducive to development of re-expansion pulmonary edema as the sternum was pulled outward, thereby increasing the negative intrathoracic pressure. Re-expansion pulmonary edema has been described as a postoperative complication after correction of PE in a kitten.20

Slowly absorbable suture material was used for plate fixation instead of nonabsorbable suture because the possibility of suture breakage and intrathoracic accumulation of suture remnants or breakdown products was undesirable. Admittedly, sutures could have been removed at the time of plate removal, but removal of the plate was not initially planned. Use of another type of suture material might have prevented the loss of achieved reduction of the deformity that occurred between 2 and 3 months after PE correction. However, after plate removal, both indices improved (VI from 8.6 to 9.6 and FSI from 1.8 to 1.6), which possibly suggests that a temporary implant might be more beneficial than a permanent implant. Another possible explanation might be that there was continued growth while the sternum remained stable. This explanation is supported by the increase in the cat's weight (approx 3.8 kg at plate removal and 5.0 kg at final follow-up evaluation) as well as increases in thoracic width (68 to 70 mm) and height (38 to 43 mm) at the level of the 10th thoracic vertebra from days 109 to 310.

Although both indices at 310 days were better than any of the previous values, they still were not within reference range. The cat did not have any signs of respiratory compromise, and the owner did not notice any dyspnea at home; therefore, we considered this to be a good result of treatment. However, the sternum still had some dorsal deviation; in the treatment of other cats with PE, this might be preventable by use of nonabsorbable suture material to prevent loss of achieved reduction of the deformity that is associated with use of absorbable suture and by contouring the plate more at the cranial end.

ABBREVIATIONS

PE

Pectus excavatum
VI

Vertebral index
FSI

Frontosagittal index
MinTH

Minimum thoracic height
a.

Veterinary cuttable plate, Synthes, Brussels, Belgium.

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  • 16.

    Sweet DC, Waters DJ. Role of surgery in the management of dogs with pathologic conditions of the thorax—Part II. Compend Contin Educ Pract Vet 1991;13:1671–1675.

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    • Export Citation
  • 17.↑

    Fossum TW, Hodges CC, Miller MW, et al. Partial sternectomy for sternal osteomyelitis in the dog. J Am Anim Hosp Assoc 1989;25:435–441.

  • 18.↑

    Moss RL, Albanese CT, Reynolds M. Major complications after minimally invasive repair of pectus excavatum: case reports. J Pediatr Surg 2001;36:155–158.

    • Search Google Scholar
    • Export Citation
  • 19.

    Ravitch MM. The operative treatment of pectus excavatum. J Pediatr 1956;48:465–472.

  • 20.↑

    Soderstrom MJ, Gilson SD, Gulbas N. Fatal reexpansion pulmonary edema in a kitten following surgical correction of pectus excavatum. J Am Anim Hosp Assoc 1995;31:133–136.

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    • Export Citation

Contributor Notes

Dr. Risselada.
Cover Journal of the American Veterinary Medical Association
Journal of the American Veterinary Medical Association
Publication Date:
01 Apr 2006
  • Figure 1
    View in gallery
    Figure 1

    Left lateral radiographic view of the thorax of a 5.5-month-old cat with dorsal deviation of the caudal portion of the sternum. Notice the marked dorsal displacement of the last 3 sternebrae. The angle between the xyphoid process and the ventral portion of the rib cage is 8°. The caudal aspect of the thoracic portion of the trachea and the carina are displaced dorsally.

  • Figure 2
    View in gallery
    Figure 2

    Schematic illustrations of the surgical intervention performed in a cat with PE. A—Transverse view. For the fifth through eighth ribs, the site of ostectomy was at the point of maximal deformation. The inner periosteum was left intact. In this panel, the left image represents the thoracic cavity prior to the surgery, and the right image represents the thoracic cavity after surgical correction has been performed. B—Lateral view. A chondrectomy was performed between the fourth and fifth sternebrae (upper image) after which the sternum was aligned and stabilized by use of a plate that was placed on the ventral surface of the sternum (lower image).

  • Figure 3
    View in gallery
    Figure 3

    Left lateral radiographic view of the thorax of the cat in Figure 1 three days after surgery to correct the deviation of the sternum. Notice that dorsal displacement of the caudal portion of the sternum is reduced (the angle between the xyphoid and the ventral portion of the rib cage is now 5°). The caudal aspect of the thoracic portion of the trachea and the carina are still displaced dorsally. The ventral border of the heart and the caudal lung lobes are blurred in the image because of mild pleural effusion. A plate has been placed on the ventral surface of the sternum, extending from the caudal midportion of the first sternebra to the ventral portion of the seventh sternebra.

  • Figure 4
    View in gallery
    Figure 4

    Left lateral radiographic view of the thorax of the cat in Figure 1 obtained at an evaluation 310 days after surgery to correct the deviation of the sternum. Notice that the caudal sternebrae are still deviated dorsally (angle 3°) but that the thoracic height is increased, compared with radiographic findings before surgery. The intersternebral space between the fourth and fifth sternebrae is collapsed, and the intersternebral space between the fifth and the sixth sternebrae is narrowed.

Figure 1

Left lateral radiographic view of the thorax of a 5.5-month-old cat with dorsal deviation of the caudal portion of the sternum. Notice the marked dorsal displacement of the last 3 sternebrae. The angle between the xyphoid process and the ventral portion of the rib cage is 8°. The caudal aspect of the thoracic portion of the trachea and the carina are displaced dorsally.
Figure 2

Schematic illustrations of the surgical intervention performed in a cat with PE. A—Transverse view. For the fifth through eighth ribs, the site of ostectomy was at the point of maximal deformation. The inner periosteum was left intact. In this panel, the left image represents the thoracic cavity prior to the surgery, and the right image represents the thoracic cavity after surgical correction has been performed. B—Lateral view. A chondrectomy was performed between the fourth and fifth sternebrae (upper image) after which the sternum was aligned and stabilized by use of a plate that was placed on the ventral surface of the sternum (lower image).
Figure 3

Left lateral radiographic view of the thorax of the cat in Figure 1 three days after surgery to correct the deviation of the sternum. Notice that dorsal displacement of the caudal portion of the sternum is reduced (the angle between the xyphoid and the ventral portion of the rib cage is now 5°). The caudal aspect of the thoracic portion of the trachea and the carina are still displaced dorsally. The ventral border of the heart and the caudal lung lobes are blurred in the image because of mild pleural effusion. A plate has been placed on the ventral surface of the sternum, extending from the caudal midportion of the first sternebra to the ventral portion of the seventh sternebra.
Figure 4

Left lateral radiographic view of the thorax of the cat in Figure 1 obtained at an evaluation 310 days after surgery to correct the deviation of the sternum. Notice that the caudal sternebrae are still deviated dorsally (angle 3°) but that the thoracic height is increased, compared with radiographic findings before surgery. The intersternebral space between the fourth and fifth sternebrae is collapsed, and the intersternebral space between the fifth and the sixth sternebrae is narrowed.
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    • Search Google Scholar
    • Export Citation
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    • Search Google Scholar
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  • 16.

    Sweet DC, Waters DJ. Role of surgery in the management of dogs with pathologic conditions of the thorax—Part II. Compend Contin Educ Pract Vet 1991;13:1671–1675.

    • Search Google Scholar
    • Export Citation
  • 17.

    Fossum TW, Hodges CC, Miller MW, et al. Partial sternectomy for sternal osteomyelitis in the dog. J Am Anim Hosp Assoc 1989;25:435–441.

  • 18.

    Moss RL, Albanese CT, Reynolds M. Major complications after minimally invasive repair of pectus excavatum: case reports. J Pediatr Surg 2001;36:155–158.

    • Search Google Scholar
    • Export Citation
  • 19.

    Ravitch MM. The operative treatment of pectus excavatum. J Pediatr 1956;48:465–472.

  • 20.

    Soderstrom MJ, Gilson SD, Gulbas N. Fatal reexpansion pulmonary edema in a kitten following surgical correction of pectus excavatum. J Am Anim Hosp Assoc 1995;31:133–136.

    • Search Google Scholar
    • Export Citation

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