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.

Description of a rare osteochondrosis lesion of the medial aspect of the distal intermediate ridge of the tibia in seven Thoroughbred horses (2008-2018).

Osteochondritis dissecans (OCD) of the distal intermediate ridge of the tibia (DIRT) is commonly identified on either the lateral to medial (LM) or dorso45°medial-plantarolateral oblique (D45M-PLO) projection of the tarsus. This manuscript describes a retrospective case series out of Hagyard Equine Medical Institute, for which medical records and radiographic projections of the tarsus were reviewed, consistent with Keeneland's repository requirements. This original investigation identified seven yearling Thoroughbred horses between 2008 and 2018 with radiographic signs of atypical osteochondrosis lesions within the tarsus. The atypical lesions, originating along the medial margin of the distal intermediate ridge of the tibia, were initially only diagnosed on the dorso10°lateral-plantaromedial (D10L-PMO) projection and were overlooked on the LM and D45M-PLO views. Following the diagnosis of osteochondrosis in these seven cases, the radiographs were reviewed and re-evaluated, but osteochondrosis and/or fragmentation could not be definitively diagnosed on the LM and/or D45M-PLO projections alone. Our findings highlight the importance of a complete radiographic study of the equine tarsus when screening horses for OCD lesions of the distal intermediate ridge of the tibia and that atypical DIRT lesions may go undetected if the D10L-PMO projection is not performed.