Intersurgeon agreement in determining 3 cm surgical margins of subcutaneous tumors in dogs.

OBJECTIVE: To evaluate intersurgeon agreement in performing a 3 cm wide surgical excision for subcutaneous malignancies in dogs. STUDY DESIGN: Prospective, blinded, randomized, clinical study. ANIMALS: Client-owned dogs with subcutaneous tumors undergoing curative-intent, wide surgical excision between April 2019 to March 2020. METHODS: Four surgeons, instructed to perform a 3 cm wide excision, each sequentially indicated their proposed skin incision locations around subcutaneous tumors, without knowledge of the other surgeons' proposed incisions. A tripod-mounted camera and laser positioning system were used to photograph each surgeon's proposed margin length. A random-effects model was used to estimate the standard deviation of margin lengths that would be expected from a random sample of surgeons. RESULTS: Each of the four surgeons provided 33 independent radial measurements from 11 tumors (six soft tissue sarcomas and five mast cell tumors), for a total of 132 radial measurements. No individual surgeon consistently proposed longer or shorter margin incision locations. The prediction interval for a future margin measurement was 6 mm, implying that the 95% confidence interval of an individual surgeon's margin length would be within ±6 mm of the mean margin length from a random sample of surgeons. CONCLUSION: Ninety-five percent of surgeons would be expected to deliver a surgical dose between 2.4-3.6 cm, for a theoretically uniform surgical dose of 3 cm wide margins. CLINICAL SIGNIFICANCE: Surgical doses are likely to vary at clinically relevant levels among surgeons, complicating design and interpretation of studies attempting to identify an ideal surgical dose.

Experience level as a predictor of entry into the hypotympanum during feline total ear canal ablation and lateral bulla osteotomy.

OBJECTIVES: The study hypotheses were as follows: (1) owing to the unique anatomy of the feline middle ear, the hypotympanum would be entered in less than 100% of cats during total ear canal ablation and lateral bulla osteotomies (TECA-LBOs); and (2) incomplete penetration of the septum and subsequent failure to enter the hypotympanum is more likely to occur in surgeries performed by a novice surgeon when compared with an experienced surgeon and may be under-recognized. METHODS: Head CT was performed in 12 feline cadavers to confirm absence of gross ear disease. A novice surgeon and an experienced surgeon were randomly assigned to perform TECA-LBO on the left or right ear. Surgeons were blinded to each other's surgical technique. CT of cadavers was performed after the procedure. Successful penetration of the septum, entry into the hypotympanic cavity and amount of bone removed in bulla osteotomy, quantified via CT, were compared between the novice surgeon and experienced surgeon. RESULTS: The novice surgeon entered the hypotympanum in 3/12 (25%) procedures, compared with 9/12 (75%) procedures performed by the experienced surgeon. The experienced surgeon performed a larger osteotomy than the novice surgeon (3301 mm vs 1376 mm, P <0.0023). Regardless of surgeon experience, more bone was removed in surgeries in which the hypotympanum was entered. CONCLUSIONS AND RELEVANCE: Our results underscore the need for familiarity with feline middle ear anatomy when performing TECA-LBOs. Postoperative CT is recommended for novice surgeons to confirm entry into the hypotympanum.

Factors associated with early tibial tuberosity fracture after tibial plateau leveling osteotomy.

OBJECTIVE: To determine factors contributing to tibial tuberosity fracture (TTF) after tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: Retrospective case-control study. ANIMALS: Dogs (n = 2490) with cranial cruciate ligament rupture that underwent 3000 TPLO surgeries. METHODS: Radiographs of 3000 stifles from dogs that underwent TPLO were reviewed for evidence of TTF. Two ratios were generated: (1) the height of the tuberosity over the width of the tibia at the most distal extent of the osteotomy (TW) and (2) the width of the narrowest point of the tuberosity over TW. RESULTS: Twenty-three (0.77%) cases of fracture were identified. Factors that correlated with increased odds of fracture were placement of antirotational pins distal to the insertion of the patellar ligament (PL), tuberosities with the narrowest point below the insertion of PL, placement of multiple pins distal to the PL, and bilateral simultaneous TPLO. Tuberosities that fractured were significantly taller and narrower than those that did not fracture. Rotation past the "safe point" and presence of a gap at the osteotomy were not correlated with fracture. CONCLUSION: Placement of multiple pins, pin placement distal to the insertion of the PL, location of the narrowest point of the tibial tuberosity distal to the insertion of the PL, and simultaneous bilateral TPLO were all associated with TTF in this study CLINICAL SIGNIFICANCE: Preoperative planning and postoperative assessment of TPLO should take into consideration the predisposing factors identified in this study to prevent TTF.