Pelvic Fractures in Small Animals: Retrospective Study of the Cases Assisted in the Veterinary Hospital of the Federal University of Lavras From January 2001 to July 2008
L.R. Mesquita; L.A.L. Muzzi; W.G. Silva; R.A.L. Muzzi; A.T. Giannico
Federal University of Lavras, Veterinary Medicine Department, Lavras, Brazil
Pelvic fractures comprise approximately 20% to 30% of all bone fractures in small animals (Smith 2004). It is believed that 25% of them are associated with motor vehicle accidents, but other causes can be mentioned like gunshot injuries, animal fights, falls from high heights and other traumas (Johnson & Hulse 2005). Fractures of the pelvis are common and they are often multiple, usually involving two or more bones, due to the fact of the pelvis to possess a boxlike structure (Houlton & Dyce 1994). Fractures of the acetabulum can change the articular congruity and can result in degenerative joint disease if they are not treated appropriately. Acetabular structure is involved in 14% to 43% of the cases in dogs, but it is little affected in cats (Boswell et al. 2001). Predisposition does not exist for race, age or sex in the pelvic fractures in small animals (Johnson & Hulse 2005). Associated with the clinical exam, the assessments at conventional radiographic in the ventrodorsal, lateral and, eventually, oblique projections are necessary for the appropriate diagnosis and for the choice of the ideal treatment (Smith 2004). The healing is facilitated by the great proportion of cancellous bone and for the stability proportionate for the adjacent musculature that it favors the bone repairing. The largest complications related to the fractures of the pelvis are the lesions of the pelvic structures and the nerves, mainly the sciatic nerve, and these lesions should be evaluated carefully for an appropriate treatment, which can be conservative or surgical (Houlton & Dyce 1994). Except for the acetabular fractures, the conservative treatment presents good results in most of the pelvic fractures (Johnson & Hulse 2005). The conservative treatment aims to provide the animal rest, analgesia and control of the urination and defecation. Moreover, the surgical treatment attempts the open reduction and internal fixation of the fractures through orthopedical implants, like the plates and bone screws (Houlton & Dyce 1994). The purpose of this work was to accomplish a retrospective study of the pelvic fractures in small animals assisted in the Veterinary Hospital of the Federal University of Lavras from January 2001 to July 2008.
Materials and Methods
A retrospective study about pelvic fractures in small animals assisted in the Veterinary Hospital of the Federal University of Lavras was accomplished from January 2001 to July 2008. In this study were included 59 animals diagnosed with different types of pelvic fractures, being 53 dogs and 6 cats. In the retrospective evaluation of the cases it was studied the history of the animals, the cause of the lesion, the elapsed time of the trauma to the attendance, the pelvic structures involved and the clinical signs presented. After evaluation of the medical records, it was followed for the radiographic study of these animals identified with the lesion, classifying the fractures as to the affected bone, its anatomical location, degree of bone lesion, type and direction of the fracture and deviation of the bone fragments. It was also evaluated the type of treatment used for each case, identifying if there was surgical intervention or conservative therapy. It was also observed the recovery of the animals and the possible occurrence of complications. The obtained data were appraised through the descriptive statistical analysis and chi square test.
In the period stipulated for the study, there were evaluated 59 animals with pelvic fractures; among them were 53 dogs and 6 cats. Among the dogs, the sampling was constituted in 43% of females and 57% of males, while in the cats it was of 34% and 66%, respectively. The pelvic fractures represented 22.9% of all the fractures assisted at the hospital, being constituted the fracture type more commonly diagnosed in this period. The hit by motor vehicles represent 95% of the causes of the fractures, being 4% by falls from high heights and 1% of unknown causes. The time elapsed between the injury to the first attendance was variable. Only six animals (10.1%) were assisted in the same day of the lesion had happened. In 22 animals (37.3%), it was assisted 24 hours after the trauma. Others 22% of the cases were assisted around 48 hours after the accident and 15.3% between 72 and 96 hours after. However, these intervals did not interfere in the result of the instituted treatment. The bones more commonly involved by the fractures were the wing of the ilium (33.3%), the ischium (22.9%) and the pubis (25%), those without great displacements of the fractured fragments. The number of fractures in the bones of the pelvis was higher than the number of affected animals because most had multiple fractures in this structure. The sacroiliac luxation was observed in 25.4% of the cases, being usually associated to the other fractures of the pelvic skeleton. The acetabular fractures were observed in nine dogs that corresponded to 15.25% of the cases. Regarding the treatment used, 49 animals (83.1%) were treated by conservative way, which consisted of rest of the animal, administration of nonsteroidal antiinflammatory drugs and, in some cases, use of cathartics. The surgery was performed in only three animals, being two cases for open reduction and internal fixation of acetabular fracture with reconstruction plate and a case for internal fixation of the ilial wing through neutralization plate in that were important displacement of the bone fragment and nervous compression. The excision of the femoral head and neck was accomplished in three cases (5.08%) in that the fractures of the acetabulum were considered irreparable. The compromising of other organs or systems took to the option of the euthanasia in three animals and the irreversible disturbance of the blood circulation culminated with the amputation of the pelvic limb in a dog. The complications after the treatment were observed in only two cases (3.39%). In one of them, the dog was submitted to the surgery of acetabular reconstruction and had occurred an implant failure, which led to the incongruity of the coxofemoral joint and consequent osteoarthritis development. Later, in this same animal, it was performed the excision of the femoral head and neck, which resulted in the functional return of the pelvic limb. In another case, a bitch submitted to the conservative treatment had pelvic canal stenosis, being indicated the preventive ovariohysterectomy. All the animals selected for the conservative treatment presented good recovery, with return to the normal activities.
Discussion and Conclusions
The high incidence of pelvic fractures observed in this study is in agreement with the citation of Smith (2004) in that the fractures involving the pelvis corresponds to 20% to 30% of the all bone fractures. This study showed approximately 10% of pelvic fractures in cats, while there are works that report them around 22% (Langley-Hobbs et al. 2006). It was also demonstrated that the great majority of the pelvic fractures had as aetiology the motor vehicles accidents, that it comes similar to the studies of Houlton & Dyce (1994) and Tomlinson (2007). However, this data differ from the citation of Boswell et al. (2001) that reports only 25% of the fractures of the pelvis being associated to the overrunning. It is believed that this high incidence is related to the fact of the large number of wandering dogs and also for animals that walking without leash. Besides, there are reports that describe the seasonal incidence due to the high heat frequency in the bitches in the spring and autumn periods, predisposing to the automobile accidents (Costa & Schossler 2002). The present study showed that the interval between the occurrence of the accident and the attendance did not alter the recovery of the animals; however it was important in the decision of instituting the conservative treatment, because 48 hours after the fracture it becomes difficult to make the surgical reduction due to the intense muscular contraction and formation of adherences (Denny & Butterworth 2006). The surgery for reduction of the sacroiliac luxation is recommended in most of the cases, because the femoral and sciatic nerves are located close to the sacroiliac joint. For this reason, a sacroiliac luxation can cause neurological injury, besides the difficulty in sustaining the corporal weight since this joint is very important in the mechanism of sustentation of the body (Johnson & Hulse 2005). However, this study showed that all the animals with sacroiliac luxation were treated in a conservative way and they presented excellent recovery with good weight support on the pelvic limbs. The incidence of acetabular fractures was of 15.23% and it coincides with the values published already, which vary from 14% to 30% (Hardie et al. 1999) and also from 14% to 43% (Boswell et al. 2001). The absence of acetabular fractures in cats is in agreement with reported by Johnson & Hulse (2005), which affirms that this location is rare in this species. However, it contradicts Langley-Hobbs et al. (2006), which reports that 17.5% of the pelvic fractures in the cats are located in the acetabulum. The most animals with pelvic fractures can recover with the conservative treatment, however the instability of the bone fragments, the pelvic canal stenosis, the limited range of motion of the coxofemoral joint and the fractures involving the areas of weight support results in the option of surgical treatment (Denny & Butterworth 2006). Among the animals with pelvic fractures presented in this study, most was submitted to the conservative treatment by the fact they do not have the characteristics mentioned previously. However, there were two cases in that the surgical treatment was indicated and the owner did not authorize due to financial subjects, being the owner aware about the reserved prognostic. That kind of conduct is in agreement with the reported literature (Johnson & Hulse 2005). This study presented high success index in the pelvic fractures treated in a conservative way. The fractures of the acetabulum and those that cause nervous lesion need surgical treatment, because a correct anatomical reduction of the acetabulum prevents the development of the degenerative joint disease. The election implants are the reconstruction plates or the acetabular plates (Houlton & Dyce 1994; Hardie et al. 1999; Boswell et al. 2001; Denny & Butterworth 2006). The complication observed in the implant of the acetabulum is in agreement with mentioned in other studies, which reports that among the complications associated with the repair of acetabular fractures are the implant failure originating from loosening of the screw or breaks of the bone plate, osteoarthritis related to the incongruity of the joint, malunion and nonunion of the fracture (Tomlinson 2007). The excision of the femoral head and neck is indicated as a treatment option for irreparable fractures. However this procedure does not dispense the stabilization and fixation of the acetabulum with bone plate to reduce the pain, to stimulate the early return of the limb and to provide stability to the hemipelvis (Smith 2004; Johnson & Hulse 2005; Tomlinson 2007). The excisions of the femoral head and neck performed in this study were always considered as the last alternative, when the presence of severely comminuted fractures did not allow the acetabular reconstruction and consequently the preservation of the coxofemoral joint. The animals submitted to the excision of the femoral head and neck showed good recovery probably because they were small sized dogs and presented favorable results with this technique (Denny & Butterworth 2006). The pelvic canal stenosis is a complication that happens occasionally after the pelvic fractures, and this is an important factor to be evaluated in reproductive female dogs. Therefore, bitches used for reproduction presented with fractures in pelvis should be appraised in the preoperative for the width of the pelvic canal, being the surgery occasionally indicated to avoid the pelvic stenosis and hereafter dystocic birth (Denny & Butterworth 2006). The present study demonstrated that the most of the fractures in pelvis does not need surgery. The conservative treatment was shown to be very effective in relation to recovery of the normal weightbearing. The taxes of complications were minimum, and these results show that it should evaluate each case of pelvic fracture carefully and that the conservative treatment can be instituted in most of the cases with great success rate.
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