Abstract
Objectives
The aim of the study was to evaluate the management and long-term outcome of cats with pelvic fractures.
Methods
Cats with pelvic fractures had their records and radiographs reviewed. Radiographs were reviewed for fracture configuration, implants and pelvic canal narrowing. Owners were contacted for long-term follow-up.
Results
Forty-three cats met the criteria (mean follow-up 24 months [range 6–45 months]). The majority (93%) had more than one orthopaedic pelvic injury, with sacroiliac fracture luxations seen most commonly; 23% had presurgical neurological deficits. Most cats (74%) were managed surgically; 60% of sacroiliac fracture luxations, 82% of ilial fractures and 50% of acetabular fractures received surgery. The complication rate was 22%, most commonly sciatic neurapraxia (13%). Seventy-nine percent of all neurological deficits resolved and the remainder improved. Mean pelvic canal narrowing after trauma was −15% in surgical and −16% in conservatively managed cats. Canal width was improved postoperatively (–8%) but mildly narrowed further by follow-up (–12%); however, these changes were not significant. Nineteen percent of cats had constipation postsurgery; none developed megacolon. There was no clear correlation between the degree of narrowing of the pelvic canal up to −50%, or whether conservative treatment was opted for, and the development of constipation. Long-term mobility was not impaired in 86% of cats, and 84% did not have any lameness detectable.
Conclusions and relevance
The majority of cats were managed surgically, with a 22% complication rate; the most common being transient sciatic neurapraxia. Long-term outcome was generally excellent and most had a full recovery. Constipation/obstipation was very uncommon and no clear relationship with pelvic canal narrowing could be found when considering narrowing of up to −50% in both surgical and conservative groups. As no cats in this cohort had narrowing greater than −50%, the current recommendation of surgery to improve the canal width if narrowing is greater than −45% to −50% should remain.
Introduction
Pelvic fractures are common, accounting for 20–32% of cat fractures.1–3 In a large retrospective study from the early 1990s, of 103 cats with pelvic fractures, 90% of cats had pelvic floor fractures, 60% had suffered a sacroiliac luxation and 49% had ilial fractures. 2 Historically, feline pelvic fractures were commonly managed conservatively;1,4 however, there has been a shift to surgical management in recent years, borrowing criteria from canine pelvic fracture management. 5 Indications for surgery have included pelvic canal narrowing, disruption of the weightbearing axis (acetabular, ilial body or sacroiliac luxations), nerve impingement, intractable pain, inability to ambulate within a few days of injury and bilateral/concomitant orthopaedic injuries. 5 Associated non-orthopaedic injuries are also common, including urinary tract trauma and neurological deficits being reported in 59–72% of cases.2,3 Various techniques have been used to stabilise pelvic fractures in dogs and cats.6–20 Several complications are typically associated with pelvic fractures. Persistent or subsequent narrowing to the pelvic canal of greater than −45% has been suggested to be a risk factor for obstipation/constipation. 17 If left unattended it may progress to megacolon, requiring life-long medical treatment or surgical alternatives such as subtotal colectomy and/or pelvic osteotomy.21–24 Therefore, this degree of narrowing has been taken to be an indicator for surgical intervention in cats. 5 Peripheral nerve damage has also noted to be associated with pelvic fractures, especially ilial fractures, owing to the proximity of the sciatic nerve.3,5,25 A degree of lameness or decrease in mobility is also commonly cited after pelvic fracture; however, there is sparse evidence to support this.
Currently, there are only limited reports on management of feline pelvic fractures that include surgical management, and very limited data on their long-term outcomes. This study aims to evaluate the management of feline pelvic fractures, the occurrence of complications, whether there is an association with pelvic canal size and constipation, and what the subsequent long-term outcome is for cats with pelvic fractures.
Materials and methods
Medical records (January 2010 to January 2014) of cats admitted with pelvic fractures were reviewed. Inclusion criteria were presence of any of the following: acetabular, ilial, ischial, pubic fractures and sacroiliac fracture luxation, managed either conservatively or surgically, with preoperative radiographs available. Surgically managed cats had to have postoperative and follow-up radiographs. Cats were excluded if follow-up with an owner-assessed questionnaire of >6 months postfracture was not available. Retrieved data included signalment, fracture configuration, preoperative neurological assessment, method of management, postoperative neurological assessment and complications. Cats were determined to have cauda-equina signs when there was a diagnosis recording ‘tail-pull’, ‘cauda-equina’, ‘sacrococcygeal nerve impairment’, or the clinical notes recorded a flaccid bladder requiring expression/catheterisation/tube cystostomy; a lack of tail sensation/movement; reduced or absent anal tone; or an absent or decreased perineal reflex. Sciatic neurapraxia was attributed when sciatic nerve damage was recorded as a diagnosis, or from the clinical notes where a reduced withdrawal reflex was noted with lack of flexion at the hock, and/or reduced or absent deep pain sensation at the paw, or knuckling was noted in the absence of other hindlimb pathology.
Radiographic evaluation included assessment of both lateral and ventrodorsal view radiographs to determine the fracture configuration, pelvic canal narrowing presurgery, postsurgery and at follow-up using the sacral index (SI). 17 All measurements were performed in triplicate and the degree of narrowing was categorised as mild (less than −10%), moderate (−10% to −30%) and severe (greater than −30%). 17 A negative value indicated narrowing and a positive value indicated widening of the canal above the predicted normal width based on the SI measurement. All radiographic evaluation was performed using DICOM imaging software. (Osirix version 4.1 64-bit open-source DICOM viewer; Osirix Imaging Software, http://www.osirix-viewer.com/OsiriX-64bit.html.)
Short-term clinical outcome (<3 months) and complications were determined from the patient records at follow-up appointments. Long-term follow-up (>6 months) was by postal or telephone questionnaire to owners using a previously published feline questionnaire (see supplementary material).15,17 Mobility and lameness were graded from 0–5 with descriptors for each group described to the owners. Information regarding specific signs of neurological deficits (knuckling, plantigrade stance, low tail carriage, ataxia) were also requested. Specific questions regarding urination and defaecation were made. Data were gathered, analysed (Excel [Microsoft] and SPSS v 19.0 [IBM]), and assessed for normality and descriptive statistics were performed as appropriate. Association of pelvic narrowing to constipation/obstipation was assessed by the Mann–Whitney U-test. A P value <0.05 was considered significant.
Results
Cats with pelvic fractures
Forty-three cats (mean age 71 months, range 7–219 months), met the inclusion criteria. Twenty-five cats were female (23 neutered, two entire), 18 cats were male (17 neutered, one entire). Twenty-eight cats were domestic shorthair (65%), seven were domestic longhair (16%) and eight were other breeds (19%). Fracture configurations and frequency is outlined in Table 1, and subclassification of ilial fractures are outlined in Table 2. In summary, when considering bilateral sacroiliac luxation as more than one fracture, 40/43 (93%) of cats had more than one pelvic injury (fractures/luxations). Sacroiliac fracture luxations were most common, being seen in 40/43 (93%); unilateral or bilateral pubic fractures were present in 31/43 (72%); unilateral or bilateral ischial fractures were seen in 22/43 (51%); and ilial fractures in 22/43 (51%). No bilateral ilial fractures were identified. Acetabular fractures were least common and again were only seen unilaterally, in 11/43 cats (26%).
Fracture classifications, indicating numbers (%) of cats with each fracture type
Subclassification of ilial fractures, showing ilial fracture configurations and percentage representation
All percentages rounded to nearest whole number
Management of fractures
The majority of cats (n = 32; 74%) underwent surgical stabilisation of their fractures with the remainder (n = 11; 26%) being conservatively managed. More than one surgical repair/stabilisation was performed in 19/32 cats. Management of fractures were as follows. Sacroiliac fracture luxations were surgically managed in 24/40 (60%) cases, most commonly using a unilateral or bilateral 2.0 mm or 2.7 mm lag screw. Two cats were managed with a screw and transilial pin and one had a transilial pin alone. Ilial fractures were generally managed surgically in 18/22 (82%) fractures, most commonly with a single laterally placed 2.0 mm dynamic compression plate (DCP), some with a 1.5/2.0 veterinary cuttable plate (VCP), two cats were double plated, one had a reconstruction plate with K-wires, one had a human radial 2.4 mm locking plate, and two were reconstructed using K-wires and lag screws alone. Acetabular fractures were managed conservatively in 7/12 (58%) cases; notably, these fractures tended to be along the caudal acetabular rim or were comminuted, and were combined with femoral head and neck excision in two cats. Of the surgically managed cats, two had acetabular plates, one had pins with wire and two were plated using locking or reconstruction plates. Pubic fractures were almost exclusively managed conservatively (30/31; 97%) other than one cat that had a pelvic symphyeal separation which had caused bilateral ventroversion of the hip joints and was managed by pubic symphyseal wiring. No ischial fractures were managed surgically.
The postoperative complication rate was 22% (7/32). Two cats suffered implant complications (wire breakage, screw loosening), which did not require any further management; one cat developed a surgical site swelling suspected to be infection, and the remainder had postoperative neurological deficits.
Neurological injuries
Neurological deficits were present in 10/43 (23%) cats on presentation. Sciatic neurapraxia was most common (7/10) and the remainder (3/10) had cauda-equina signs. No increase in neurological deficits was seen in the short term in conservatively managed cats; however, four cats surgically managed developed further deficits (sciatic neurapraxia) postsurgery (13%). Resolution of presurgical deficits was seen in five cats by follow-up at 6–8 weeks, and in the long term (>6 months) neurological deficits from the trauma or surgery had resolved in 11/14 (79%) of cats, and had improved in a further three. One conservatively managed cat had no detectable abnormalities at presentation but went on to develop an unsteady/wobbly gait 3 months postfracture.
Pelvic canal diameter
Mean preoperative percentage canal width was not significantly different between surgically managed cats (–15%, range −43% to +30%) and conservatively managed cats (–16%, range −42% to +4%). Postsurgery, mean canal width had widened to −8% (range −37% to +26%); however, this increase was not statistically significant. At the 6–8 week follow-up, the pelvic canal had slightly narrowed to −12% (range −51% to + 19%), with an average of increased narrowing by −4%, which was again not significant. See Table 3 for categorisation of the severity of narrowing. Constipation postfracture was seen in eight cats (19%). Two had problems at least monthly, one only twice a year and five were intermittent, suffering less than once every year. Half of the cats with constipation had visited the vet, 2/8 were medically managed and 2/8 had no treatment. Cats that developed constipation had a pelvic canal size range of −27% to +5%. ‘Severe narrowing’ of the canal of (greater than −30%)13,17 was present in six cats managed surgically and conservatively, with a range of −31% to −51%; however, none of these cats developed constipation. Only one cat in this study had narrowing greater than −45%, which has been suggested to be the cut off for increased risk of defecation problems; 17 however, it did not develop any such problems. No cats from this series were reported to develop megacolon or require any surgical intervention for problems relating to constipation/obstipation.
Classification of pelvic canal narrowing
Widening is pelvic canal diameter greater than the sacral index width. Mild narrowing = 0 to −10% narrowed, moderate narrowing = −10% to −30% narrowed and severe = greater than −30% narrowed
Long-term clinical outcome
The mean long-term follow-up was 24 months (range 6–45 months). The majority of cats (36/42; 86%) showed no signs of lameness, with only seven (17%) having some degree of permanent lameness (see Table 4). The majority of cats were felt to be mobile by their owners, with 86% ‘as expected’ to ‘very agile for their age’. Only 14% of cats were considered to have impaired mobility (Table 4).
Lameness and mobility outcomes from questionnaire
Discussion
This is the largest group of cats with pelvic fractures that have had long-term follow-up of at least 6 months after surgery. This cohort was older than previous reports, with a mean age of 71 months, compared with a mean age of <17 months. 3 The change in demographic may relate to the increase in motor vehicle traffic since those other cohorts were reviewed or the geographical effect of living in a metropolitan area.
Compared with the largest previously published study, 2 there were significantly higher levels of sacroiliac fracture luxations (93% compared with 60%), and a similar level of ilial body fractures (51.0% vs 48.5%). Acetabular fractures were the least common (26% of cats); however, this was still higher than in previous reports. 2 The higher levels of individual fracture types, or diagnosis of them, may be attributable to the use of high-detail digital radiographs, which were not present when the previous study was conducted. Furthermore, radiographs were evaluated by board-certified surgical and radiology specialists, potentially increasing the likelihood of detection. Although not unsurprising, as 93% of pelvic fractures had at least two pelvic orthopaedic injuries, careful evaluation of radiographs needs to be performed if only one fracture is initially identified.
Although fixation of the pelvic floor has been described in the literature, 26 this was not performed routinely in this cohort and did not appear to impact on outcome negatively. Ilial body fractures are usually an indication for surgical repair,5,15,17 and surgical stabilisation was performed in the vast majority. Some combination of lateral plating was most common, usually with a single DCP plate, and no implant complications were seen other than one cat with screw pull out in the ilial wing. This cat had a comminuted ilial fracture that was not fully reconstructed, and there was a conservatively managed sacroiliac luxation, which may have contributed to the loads placed upon the relatively thin cranial ilial wing. 15 Greater consideration may be necessary to stabilising concurrent injuries if there is any compromise in the primarily stabilised fracture.
Sacroiliac fracture luxations were managed surgically in 60% of cats. Several factors are considered when determining whether to surgically manage these fractures, including whether they are bilateral, degree of displacement, discomfort and mobility considerations, and concurrent injuries.5,18,27 Placement of a single or bilateral lag screw remains a popular and successful technique, 18 being used in most cats here (21/24). Placement of a transilial pin in conjunction with a lag screw was used in two cats that had bilateral sacroiliac luxations,5,20 and was also used as sole fixation in one cat. The transilial pin is a potentially easier technique to perform, and may have particular use for when sacral wing landmarks are lost; however, there are currently no guidelines on placement of transilial pins in cats.
Acetabular fractures were only surgically managed in 50% of cases. This is surprising as articular fractures are typically treated with reduction and rigid internal fixation, and the historic opinion that fractures in the caudal third of the acetabulum did not require surgical management has been disproved. 28 However, most of the conservatively managed acetabular fractures in this series had fracture lines that were along the caudal perimeter of the articular acetabulum and therefore the cost-to-benefit assessment may have fallen in favour of conservative treatment. The other conservatively managed fractures had degrees of comminution leading to salvage with a femoral head and neck excision.
Neurological deficits were seen in 23% of cats, and therefore careful neurological evaluation is essential in pelvic fracture cats. Fractures with proximity to other structures will inevitably increase the risk of concurrent injuries. The high frequency of sacroiliac fracture luxation and ilial fractures seen could have resulted in damage to the lumbosacral plexus, being ventral to the sacrum, and feasibly result in a degree of traction or avulsion secondary to sacroiliac fracture luxations. 29 Likewise, the position of the sciatic nerve medial to the ilial body and then passing over the cranial ischium clearly puts it at risk, and therefore the anatomical proximity would explain high levels of concurrent neurological impairment. These intimate relationships also explain the risk of surgically induced nerve impairment.25,30 During surgery great care is taken to avoid trapping or stretching nerves, especially the sciatic; however, 13% of cats did have postoperative sciatic neurapraxia. Positively, all of the traumatic and surgically induced neurological deficits improved, with 79% of cats having complete resolution and the remainder having some residual impairment, implying that the damage is likely a neurapraxia or axontemesis at worst, and not neurotemesis. Therefore, the prognosis for cats with pelvic fractures and hindlimb neurological deficits appears generally good. Only one cat in this cohort developed neurological deficits not present from the trauma or surgery. This cat was conservatively managed, had bilateral mild sacroiliac luxations and no neurological deficits on presentation. Although callus healing of bone fragments has also been suggested to place nerves at risk, 3 the cause of the subsequent weakness in this cat remains unclear.
Postoperative complications occurred in around a fifth of cats, with the majority being postsurgical sciatic neurapraxia, and therefore particular attention should be given to postoperative neurological deficits when discussing surgical management with owners. Acquired megacolon secondary to constipation/obstipation is often cited as a potential complication of pelvic fractures, due to persistent canal narrowing, and is said to account for 25% of megacolon cases.24,31,32 Pelvic canal narrowing has become a criteria for surgical management, with narrowing of greater than −45% to −50% being reported to increase the risk of megacolon and hence the cut-off for surgery. 17 However, there are other causes of megacolon, including neurological injury, sacral spinal cord deformity and, most commonly, idiopathic causes.24,31 This study had a mean follow-up of 24 months, with a minimum of 6 months, which was important as clinical signs usually begin shortly after pelvic injury but could take >5 months. 23 In this follow-up period, only eight (19%) cats were reported to have constipation. No cats were reported to develop megacolon. The cats that developed any issues with constipation had a pelvic canal size range of −27% to +5%. Severe narrowing of the canal, when defined as narrowing greater than −30% was present in six cats managed surgically and conservatively,13,17 with a range from −31% to −51%; however, none of these cats developed constipation. Only one cat in this study had narrowing greater than −45%, which has been suggested to be the cut-off for increased risk of defaecation problems. 17 From the data presented here, it appears that narrowing of up to −50% does not cause constipation. As no cats in this study had narrowing greater than −50%, the current recommendation of surgical intervention if the pelvic canal is greater than −45% to −50% narrowed should remain until a cohort of cats with narrowing of greater than −50% has been fully evaluated.
Although it is reassuring to know that the long-term outcome of cats with pelvic fractures is generally excellent, even in those with neurological deficits, there is likely to be some bias in this population. It is possible that, owing to the guarded prognosis given, some cats presenting with pelvic fractures may well have had such severe trauma, including neurological deficits, such as absence of anal tone, perineal reflex or bladder function, that they may have been euthanased. This study is also unable to determine whether surgical management is superior or not to conservative management. On the face of it, the outcomes were largely similar, and the preoperative pelvic canal narrowing was also similar. However, conservative management vs surgical was not randomly assigned, and usually related to the combinations and configurations of fractures seen. These populations of cats are therefore not the same. Despite this, this study shows that cats that received surgery and those that were intentionally conservatively managed based on current recommendations can have excellent outcomes. 5
Conclusions
Current management criteria for feline pelvic fractures appear to work well, with excellent long-term outcomes. Surgical complications are infrequent but are most commonly varying degrees of sciatic impairment. Positively, neurological deficits from the trauma or surgery resolve in most and improve in the remainder. No cats developed megacolon; however, a few did have intermittent issues with constipation, although the relationship to pelvic injuries is unclear. On balance it appears that narrowing of up to −45% to −50% is not a direct risk factor for development of constipation and megacolon; however, narrowing greater than −50% could potentially still be a risk and therefore should remain as an indication for surgical intervention.
Footnotes
Supplementary material
The questionnaire used for long-term follow-up.
Conflict of interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.