Biomechanical comparison of one pin versus two pin fixation in a canine tibial tuberosity avulsion fracture model.

OBJECTIVE: To determine whether one larger or two smaller diameter pins used for tibial tuberosity avulsion fracture (TTAF) stabilization provides greater axial tensile strength and stiffness when subjected to monotonic mechanical load to failure in normal skeletally mature canine cadavers. STUDY DESIGN: Paired ex vivo biomechanical study. SAMPLE POPULATION: Eleven pairs of adult cadaveric dog tibias. METHODS: Twenty-two tibias from 11 dogs were collected to model a TTAF. Each limb of a pair was randomly assigned a one or two-pin fixation. Tibias were subjected to monotonic, axial load to failure. Fixation stiffness, strength, and pin insertion angles were analyzed with parametric testing. Significance was set at p < .05. RESULTS: The mean strength of the single-pin fixation was 426.2 ± 50.5 N compared to two-pin fixation at 639.2 ± 173.5 N (p = .003). The mean stiffness of the single-pin fixation was 57.3 ± 18.7 N/mm and the two-pin fixation was 71.7 ± 20.5 N/mm (p = .029). The normalized ratio between one and two-pin fixation had a mean stiffness of 68% ± 25.8% and strength of 82.8% ± 24.6%. CONCLUSIONS: In an ex vivo cadaveric TTAF model, vertically aligned two-pin fixation offers greater strength and stiffness when compared to a single-pin fixation. CLINICAL SIGNIFICANCE: When repairing TTAF, surgeons should aim to apply two vertically aligned pins rather than a single pin for greater strength and stiffness.

Evaluation of a resorbable self-locking ligation device for performing peripheral lung biopsies in a caprine cadaveric model.

OBJECTIVE: To compare airway leak pressures after sealing peripheral lung biopsy sites with a resorbable ligation device (LigaTie) or thoracoabdominal (TA) staples. STUDY DESIGN: Ex vivo study. ANIMALS: Four normal caprine cadavers. METHODS: Twelve lung lobes were harvested from 4 goats immediately after euthanasia. Each lobe was inflated to 20 cm H2 O to test for leaks prior to biopsy. Pressure was then maintained at 10 cm H2 O. Biopsy samples were obtained 3 cm from the periphery with a resorbable ligation device or a TA stapler (n = 6 per group). After biopsy, inflation pressure was slowly increased to 40 cm H2 O while lungs were submerged in water. The pressure at which bubbles were first seen was recorded as the airway leak pressure. The length, width, volume, and weight were recorded for each biopsy sample. RESULTS: Five of 6 LigaTie biopsy sites sustained the maximum pressure of 40 cm H2 O without leaking. One site leaked at 24 cm H2 O. The TA-stapled sites sustained airway pressure to median 25.5 cm H2 O (interquartile range, 23.5-26 cm H2 O), and none of them reached the maximum pressure (P = .015). There were no differences in biopsy length, volume, or weight between groups. CONCLUSION: Biopsy sites sealed with LigaTie withstood higher airway pressure without leaking compared with TA-stapled biopsy sites in normal cadaveric specimens. CLINICAL SIGNIFICANCE: The LigaTie may be an alternative technique for sealing peripheral lung biopsy sites.

Thoracoscopic-assisted lung lobectomy in cat cadavers using a resorbable self-locking ligation device.

OBJECTIVE: To compare the maximum pressure sustained by airways sealed with a resorbable ligation device (LigaTie) and with thoracoabdominal (TA) staples during thoracoscopic-assisted hilar lung lobectomies. STUDY DESIGN: In situ cadaveric study. ANIMALS: Ten feline cadavers. METHODS: Twenty lung lobectomies were performed with either a LigaTie or a TA stapler (n = 10 per group) by using a thoracoscopic-assisted technique. Procedures were randomly performed on the cranial lung lobes only. The distance between the ligation and the hilus was measured on each specimen. Airway pressures were tested to a maximum pressure of 40 cmH2 O. RESULTS: All LigaTie sites reached a maximum airway pressure without leaking and were easily placed at the hilus. Four of 10 TA stapled sites leaked at a mean pressure of 22 cmH2 O (P = .010). All leaks occurred when the TA staple line was >5 mm from the hilus; no leaks occurred when the TA staple line was ≤5 mm from the hilus (P < .001). No difference was found between fresh and frozen cadavers (P = .483) or right vs left lung lobe (P = .284). CONCLUSION: Lung lobectomies were consistently performed at the hilus only when the LigaTie was used. Lung lobectomies were less likely to leak when performed with the LigaTie rather compared with TA staples. CLINICAL SIGNIFICANCE: The LigaTie may be an effective alternative for lung lobectomies at the pulmonary hilus in cats and small breed dogs. Our findings provide justification for additional clinical testing.

Effect of patellar luxation on radiographic measurements of tibial plateau angle in small-breed dogs.

OBJECTIVE To determine whether medial patellar luxation would affect radiographic tibial plateau angle (TPA) measurements in small-breed dogs. DESIGN Prospective cross-sectional study. ANIMALS 15 small-breed dogs (25 stifle joints) with grade 2 or 3 medial patellar luxation (5 dogs with unilateral luxation and 10 dogs with bilateral luxation). PROCEDURES Digital mediolateral radiographic images of each affected stifle joint were acquired with the patella in manually reduced (n = 25) and luxated (25) positions. In 2 measurement sessions separated by > 48 hours, 3 observers unaware of patella status (luxated or reduced) measured the TPA in each image twice in random order. Mixed linear modeling was performed to determine the effect of patella status on TPA measurements, and intraobserver and interobserver variation in measurements were calculated. RESULTS TPA measurements by all observers differed significantly between the first and second measurement sessions, but by a mean value of only 0.7°. A few significant differences were identified between 1 pair of observers by patella status and between patella statuses for 1 observer, but all mean differences were ≤ 1.7°. No significant difference in intraobserver variation was identified between patella statuses for any observer. Interobserver variation was not affected by patella status and measurement session. CONCLUSIONS AND CLINICAL RELEVANCE Although some significant differences were identified in radiographic TPA measurements in dogs with medial patellar luxation, depending on whether the patella was luxated or manually reduced, these differences were so small they could be considered clinically unimportant. Consequently, we believe that in small-breed dogs with patellar luxation, patella status would be unlikely to have a clinically meaningful effect on the measured TPA.

Rates of intraoperative complications and conversion to laparotomy during laparoscopic ovariectomy performed by veterinary students: 161 cases (2010-2014).

OBJECTIVE To assess rates of intraoperative complications and conversion to laparotomy associated with supervised veterinary students performing laparoscopic ovariectomy in dogs. DESIGN Retrospective case series. ANIMALS 161 female shelter dogs for which elective laparoscopic ovariectomy had been performed by supervised senior (fourth-year) veterinary students from 2010 through 2014. PROCEDURES Medical records of all dogs were reviewed and data collected regarding duration of surgery, surgical complications and other characteristics, and whether conversion to laparotomy was required. RESULTS Laparoscopic ovariectomy was performed with a 2-cannula technique and a 10-mm vessel-sealing device for hemostasis in all dogs. A Veress needle was used for initial insufflation in 144 (89.4%) dogs; method of insufflation was not reported for the remaining 17 (10.6%) dogs. Mean ± SD duration of surgery was 114.90 ± 33.40 minutes. Surgical complications, all classified as minor blood loss, occurred in 24 (14.9%) dogs. These included splenic puncture during insertion of the Veress needle (n = 20 [12.4%]) and minor bleeding from the ovarian pedicle (4 [2.5%]). Splenic puncture required no intervention, and ovarian pedicle bleeding required application of the vessel-sealing device an additional time to control the bleeding. Two ovaries were dropped in the abdominal cavity at the time of removal. Both were retrieved without complication. Conversion to laparotomy was not required for any dog. All dogs were discharged from the hospital within 24 hours after surgery. CONCLUSIONS AND CLINICAL RELEVANCE Laparoscopic ovariectomy in dogs was performed safely by closely supervised novice surgeons, with only minor intraoperative complications encountered and no need for conversion to laparotomy.

Intrapericardial cystic hematoma in a dog treated by thoracoscopic subtotal pericardectomy.

CASE DESCRIPTION A 2-year-old castrated male mixed-breed dog was evaluated because of a 1-week history of respiratory distress and abdominal distension. Thoracic radiography and echocardiography at that time revealed an enlarged cardiac silhouette and pericardial effusion; abdominal radiography and ultrasonography revealed ascites. CLINICAL FINDINGS At the initial referral examination 5 weeks later, the dog weighed 37.5 kg (82.5 lb) and appeared clinically normal. The only abnormality detected was a grade I/VI systolic murmur on the left side of the thorax. Echocardiography revealed a large fat- and fluid-filled cystic structure located next to the right ventricle with scant pericardial effusion. Computed tomography revealed a bilobed peripherally contrast-enhancing structure within the right ventral aspect of the pericardium; the right ventricle appeared compressed by the cyst. TREATMENT AND OUTCOME Initial treatment consisted of pericardiocentesis and abdominocentesis to alleviate clinical signs. Thoracoscopic subtotal pericardectomy was performed 6 weeks after the initial treatment. The cyst was completely excised, and multiple adhesions between the visceral and parietal pericardium were transected, without surgical or anesthetic complications. Histologic examination of the cyst revealed chronic inflammation with histiocytic infiltration, suggesting possible foreign body reaction or chronic inflammation and hemorrhage. These findings supported a diagnosis of cystic hematoma of the pericardium. The dog remained clinically normal for at least 16 months after surgery. CLINICAL RELEVANCE This report represents a rare case of intrapericardial cystic hematoma in a dog. Minimally invasive surgery was performed without complications, suggesting that thoracoscopic subtotal pericardectomy is a feasible treatment option for affected dogs.