Pelvic osteotomy for pelvic canal stenosis after malunion pelvic fractures in cats

Abstract

Objectives: The aim of this study was to assess the efficacy of pelvic osteotomy and ventral fixation of the ischium using cortical screws and polymethylmethacrylate (PMMA) for feline pelvic canal stenosis (PCS) associated with malunion after conservative management of pelvic fractures.

Methods: Surgical pelvic enlargement was performed for PCS in six cats. The medical records, including information on the patients, surgical procedures, defecation and complications, were reviewed. The sacral index (SI) and colonic:lumbar:vertebral ratio (CLVR) were evaluated based on pre- and postoperative radiographs.

Results: This study included five castrated male cats and one spayed female cat. Postoperative improvements in constipation and defecatory difficulty were noted in all cases. The postoperative SI was significantly higher (mean 0.93, range 0.72-1.13) than the preoperative SI (mean 0.59, range 0.45-0.74) (P <0.001). However, no statistically significant change was found in the CLVR preoperatively and up to 3 months postoperatively. A successful union of the ilium was observed, without implant failures. One case developed necrosis of the pubic surgical wound.

Conclusions and relevance: This study indicated the potential benefits of pelvic osteotomy and ventral fixation of the pelvic floor using screws and PMMA for achieving pelvic cavity enlargement in treating feline PCS associated with defecatory problems.

Keywords: Pelvic canal stenosis; pelvic osteotomy; polymethylmethacrylate; ventral fixation.

Figure 1

(a–d) Radiographic and (e–h) intraoperative findings of case 3. Preoperative (a) ventrodorsal and (b) lateral aspects of the pelvis are shown. Postoperative (c) ventrodorsal and (d) lateral aspects of the pelvis are shown. In the ventrodorsal view, the left ilial body is displaced medially from the caudal edge of the sacroiliac joint; narrowing of the pelvic cavity is clearly observed. The width of the sacrum at the cranial border (SW) and across the width of the pelvic canal at the narrowest point, between the medial cortices of the acetabulae (AW), are indicated by arrows. These measurements are used to calculate the sacral index (SI), which is the ratio of these two measurements. Lateral radiographs show enlargement of the descending colon with marked faecal impaction and deformed fusion of the ilial body. Postoperative radiography reveals pelvic cavity enlargement. The maximum diameter of the colon (CD) and the length of L5 (L) are delineated by solid black bars. (e) Yellow dotted lines indicate the separation line of the pelvic floor osteotomy; (f) the ilium is osteotomised and fixed with a crank plate (seven holes); (g) eight anchor screws are inserted into the ventral aspect of the pelvic floor; (h) placement of polymethylmethacrylate

Figure 2

A design drawing of a typical crank plate. This shows an eight-hole crank plate. All crank plates are designed to facilitate a 7.5 mm lateral displacement of the caudal bone fragment after ilial osteotomy. Measurements on the drawing are in mm