Fixation In Dogs Research Articles

Retrospective Assessment of Thirty-Two Cases of Pelvic Fractures Stabilized by External Fixation in Dogs and Classification Proposal.

The goals of this study were to evaluate the outcomes of bone healing, patient comfort during the treatment, functional results, and complications in pelvic fractures treated with external fixation, as well as to propose a classification system for the applied external frames. A total of thirty-two canine patients with pelvic fractures of different origins were treated. To provide a better reference for the frames used, an alphanumeric classification system was developed, detailing the frame structure and the number and location of the pins used. In this study, eighty-six fractures were treated in the 32 patients of this work, with an average fixation time of 9.88 ± 4.15 weeks. No major complications were detected in this case cohort, and the outcomes were rated at 9.46 based on a visual assessment scale for the patient's comfort during treatment. Outcomes graded as excellent and good were 96%. The use of external fixation for stabilization of pelvic fractures should be considered as a technical option, especially for minimally invasive stabilization of complex fractures, either as a primary or secondary stabilization.

Fracture Healing in 37 Dogs and Cats with Implant Failure after Surgery (2013-2018).

Implant failure is common in small animal orthopedics, but risk factors are rarely reported. Our objective was to determine whether abnormal fracture healing was associated with implant failure after fracture fixation in dogs and cats in a consecutive series of cases. Thirty-seven client-owned animals (thirty-two dogs, five cats) diagnosed with implant failure after fracture treatment from January 2013-September 2018 were studied. Medical and radiographic records were retrospectively reviewed to identify patients that underwent fracture fixation using open reduction and internal fixation with subsequent radiographic evidence of implant failure. Area moment of inertia (AMI), plate working length, and bone screw density were determined. Implant failure was found in 39 fractures in 37 animals, representing 23% of fracture cases during the study period. Cases of implant failure were at increased risk of delayed union, malunion, or non-union (p < 0.0001). The most common cause of implant failure was loosening (54%); the second most common was plate failure that included low AMI locking plates (28%). Major complications found in 22/39 fractures (56%) were associated with delayed union (p < 0.01). Surgical revision was performed in 49% of implant failure cases. Complications were most frequently identified after treatment of humeral fractures (26%). We conclude mechanical failure of implants increases the risk for delayed or abnormal fracture healing and often requires revision surgery. Implant AMI should be considered during preoperative planning. Locking plates are associated with implant failure if plate bending stiffness is not sufficient, based on findings from this case series.

Biomechanical Comparison between Inverted Triangle and Vertical Configurations of Three Kirschner Wires for Femoral Neck Fracture Fixation in Dogs: A Cadaveric Study.

The purpose of this study was to compare single-cycle axial load and stiffness between inverted triangle and vertical configurations of three Kirschner wires (K-wires) for femoral neck fracture fixation in small dog cadaveric models. In each of the eight cadavers, the basilar femoral neck fracture model was prepared on both sides of the femur. One side of the femur was stabilized with three 1.0 mm K-wires of an inverted triangle configuration (group T), and the other femur was stabilized with a vertical configuration (group V). Postoperatively, the placement of the K-wires was evaluated with radiographic and computed tomography (CT) images, and static vertical compressive loading tests were performed. The mean yield load and the lateral spread were significantly higher in group T compared to group V (p = 0.023 and <0.001). On the cross-section of femoral neck at the level of the fracture line, the surface area between K-wires was significantly larger (p < 0.001) and the mean number of cortical supports was significantly higher in group T (p = 0.007). In this experimental comparison, the inverted triangle configuration of three K-wires was more resistant to failure under axial loading than the vertical configuration for canine femoral neck fracture fixation.

Influence of Kirschner-Wire Insertion Angle on Construct Biomechanics following Tibial Tuberosity Osteotomy Fixation in Dogs.

The aim of this study was to evaluate the effect of Kirschner wire insertion angle on the biomechanical characteristics following tibial tuberosity osteotomy fixation in dogs. Twelve pairs of cadaveric tibia were harvested and randomly assigned to two treatment groups. Kirschner wires were placed either transversely (0 degrees) or placed caudodistally (30 degrees) with respect to the tibial tuberosity osteotomy. Each limb acted as its own respective control. Radiographic analysis allowed for the calculation of Kirschner wire insertion angle variance. Constructs were tested to monotonic failure while evaluating yield, peak, and failure forces, construct stiffness, and failure mode. Kirschner wire insertion angles were 1.1 ± 2.2 degrees and 30.5 ± 2.3 degrees, respectively, for 0-degree and 30-degree groups (p <0.0001). Yield (p = 0.0095), peak (p <0.024) and failure loads (p <0.030) were all significantly greater for Kirschner wires inserted at an angle of 0 degrees compared with 30 degrees. Construct stiffness did not differ regardless of insertion angle (p = 0.068). Failure mode did not differ (p = 0.87) with tibial tuberosity avulsion and Kirschner wire pull-out seen in the majority of constructs (67%). Kirschner wires placed transversely (0 degrees) for tibial tuberosity osteotomy fixation were biomechanically superior, increasing yield, peak, and failure forces by 1.6 times, 1.3 times, and 1.4 times, respectively, to those placed in a caudodistal (30 degrees) orientation. Kirschner wire insertion angle is an important consideration following tibial tuberosity osteotomy in dogs, with Kirschner wires placed at 0 degrees conferring increased resistance of the repair to construct deformation.

Computer-Assisted Surgery Using 3D Printed Saw Guides for Acute Correction of Antebrachial Angular Limb Deformities in Dogs.

The aim of this study was to report the use of custom saw guides produced using computed tomographic imaging (CT), computer simulation and three-dimensional (3D) printing to aid surgical correction of antebrachial deformities in six dogs. Antebrachial limb deformities in four small, and two large, breed dogs (seven limbs) were surgically corrected by a radial closing wedge ostectomy and ulnar osteotomy. The location and orientation of the wedge ostectomy were determined using CT data, computer-assisted planning and production of a saw guide in plastic using a 3D printer. At surgery, the guide was clamped to the surface of the radius and used to direct the oscillating saw blade. The resultant ostectomy was closed and stabilized with a bone plate. Five limbs healed without complications. One limb was re-operated due to a poorly resolved rotational component of the deformity. One limb required additional stabilisation with external fixation due to screw loosening. The owners of five dogs completed a Canine Orthopedic Index survey at a follow-up period of 37 to 81 months. The median preoperative score was 3.5 and the median postoperative score was 1, representing an overall positive effect of surgery. Radiographically, 5/7 limbs were corrected in the frontal plane (2/7 were under-corrected). Similarly, 5/7 limbs were corrected in the sagittal plane, and 2/7 were over-corrected in the sagittal place. Computer-aided design and rapid prototyping technologies can be used to create saw guides to simplify one-stage corrective osteotomies of the antebrachium using internal fixation in dogs. Despite the encouraging results, accurate correction of rotational deformity was problematic and this aspect requires further development.

Atlantooccipital overlapping and its effect on outcomes after ventral fixation in dogs with atlantoaxial instability.

We compared clinical outcomes after ventral fixation in dogs with atlantoaxial instability (AAI) on the basis of the presence or absence of atlantooccipital overlapping (AOO). Of 41 dogs diagnosed with AAI and treated ventral fixation, 12 exhibited AOO (AOO group), whereas 29 did not (non-AOO group). The AOO group had significantly higher neurological scores before (P=0.024) and 1 month after (P=0.033) surgery compared with the non-AOO group; however, no significant differences were observed between the groups 2 months after surgery. The presence of complicating AOO affected the clinical signs for dogs with AAI, but did not directly affect the outcome of surgical stabilization of AAI.

Augmentation of diaphyseal fractures of the radius and ulna in toy breed dogs using a free autogenous omental graft and bone plating.

Evaluation of the short-term outcome, duration of bone healing, and complications following bone plate fixation in dogs weighing ≤6 kg, with and without the use of a free autogenous greater omental graft (OG). A retrospective clinical study reviewed the medical records of 25 dogs of body weight <6 kg with mid to distal diaphyseal fractures of the radius and ulna (29 fractures) treated with open reduction bone plate fixation. Thirteen out of 29 fractures were implanted with an additional 2-3 cm³ OG lateral, cranial, and medial to the fracture site, adjacent to the bone plate. Median time to radiographic healing in OG fractures (n = 11) was 70 days (range 28-98) compared to 106 days (range: 56-144) in non-OG grafted fractures (n = 14). The OG dogs had no major complications; minor complications included oedema, erythema, and mild osteopenia. Six of the eight non-OG dogs for which follow-up could be obtained developed osteopenia necessitating implant removal, four of which re-fractured the radius one to five months after implant removal, with one dog re-fracturing the limb a second time and resulting in amputation. Telephone follow-up of owners of OG dogs (n = 11) three to 15 months (median 10) post-surgery did not identify any signs of lameness or other complications. Owners of the non-OG dogs (n = 8) reported that there were not any signs of lameness six to 48 months (median 36) post-surgery. Free autogenous omental grafting of diaphyseal fractures of the radius and ulna was associated with radial and ulnar healing with minimal complications in dogs weighing less than 6 kg.

Transarticular Fixation With Cortical Screws Combined With Dorsal Laminectomy and Partial Discectomy as Surgical Treatment of Degenerative Lumbosacral Stenosis in 17 Dogs: Clinical and Computed Tomography Follow‐Up

To describe clinical outcome and technical outcome assessed using computed tomography (CT) in dogs with degenerative lumbosacral stenosis (DLSS) treated by dorsal laminectomy, partial discectomy, and transarticular screw fixation. Retrospective observational case series. Dogs with DLSS (n = 17). Dogs with neurologic and magnetic resonance imaging (MRI) findings compatible with DLSS treated by dorsal laminectomy, partial discectomy and transarticular screw fixation were enrolled. Pre- and postoperative neurologic status was compared. Lumbosacral (LS) angle in extension and misalignment in preoperative MRI were compared with the postoperative CT. Residual mobility of the LS joint after fixation was also evaluated. Status of screws, presence of new bone formation over screw heads/articular facets and presence of adjacent segment disease (ASD) were assessed. Median CT follow-up was 12 months. Clinical improvement was seen in 13 dogs, 2 dogs had intermittent LS pain, and 2 dogs needed revision surgery. In 5 dogs, screws were either pulled out or broken. Reduction of LS angle in extension and misalignment was achieved. Residual mobility of the LS segment was present and ASD was not recognized. Transarticular screw fixation in dogs with DLSS is associated with a considerable number of technical failures and does not result in rigid stabilization; however, this did not significantly adversely influence clinical outcome.

Healing and expression of growth factors (TGF-β and PDGF) in canine radial ostectomy gap containing platelet-rich plasma

To evaluate bone healing in an experimental radial ostectomy in dogs treated with autologous platelet-rich plasma (PRP), through histological, densitometric, radiographic studies, as well as expression of growth factors in the ostectomy gap. Twenty-one dogs were randomly divided into either a control or a PRP group. All underwent unilateral ostectomy of the radius to generate a gap of 2.0 mm, that was stabilized with external skeletal fixation. The ostectomy gap was either filled with PRP or left empty as a control. The radiographic and densitometric studies were performed after surgery, then at intervals until 60 days during the post-surgery period. Histological and immunohistochemical evaluations were performed at seven or 60 days post-surgery. Analyses were performed using a statistical analysis system, and the level of significance was set at p <0.05. The median radiographic healing score in the PRP group increased significantly between day 0 and day 60. Furthermore, at 60 days, the median healing score and the proportion of healed ostectomies in the control group (score 1; 1/6 healed) and the PRP group (score 5; 4/5 healed) were significantly different. There were differences between groups in radiographic and densitometric values at days 45 and 60. The histological evaluation showed advanced bone healing at 60 days in the PRP group and signs of delayed union in the control group. Platelet-rich plasma can be used as an adjuvant therapy because it may promote better bone healing of a radial ostectomy treated with external skeletal fixation in dogs.

Intracapsular lensectomy and sulcus intraocular lens fixation in dogs with primary lens luxation or subluxation

To evaluate the postoperative results of lensectomy and sulcus intraocular lens fixation (SIOLF) via an ab interno approach in dogs with progressive lens subluxation or early luxation. Retrospective study. Twenty eyes from 19 dogs presented to the Animal Eye Clinic for lens luxation or subluxation between 1999 and 2006. Medical records were reviewed to evaluate preoperative lens position, vision status, intraocular pressure (IOP), and whether surgery was performed on an emergent or elective nature. Lensectomy and SIOLF were performed and postoperative status including vision, glaucoma, and retinal detachment was assessed. Average age was 8.6 years (range 4-14 years) and 55% (11/20) were terriers. Patients were followed a mean of 29.2 months (range 1-92 months) after surgery. Retinal detachment or secondary glaucoma was observed in 1 of 20 (5%) and 5 of 20 (20%) eyes, respectively, with 1 of 20 (5%) exhibiting both. Mean preoperative IOP was 16 mmHg and preoperative lens position was equally divided between luxated and subluxated lenses. Surgery was performed more frequently as an elective procedure (18/20; 90%) due to normalized IOP vs. an emergency procedure (2/20; 10%). Vision was retained in 70% (14/20) of eyes with a mean time to vision loss of 41 months in the remaining eyes due to glaucoma, retinal detachment, or retinal degeneration. Complications of glaucoma and retinal detachment after SIOLF in this study were less when compared with previously reported incidence rates in the literature for lensectomy alone which may reflect improved patient selection.

Treatment of Long Bone Fractures with Acrylic External Fixation in Dogs and Cats: Retrospective Study in 30 Cases (2006-2008)

Treatment of Long Bone Fractures with Acrylic External Fixation in Dogs and Cats: Retrospective Study in 30 Cases (2006-2008)

Complications following tarsal arthrodesis using bone plate fixation in dogs

To report the complications encountered following tarsal arthrodesis surgery with bone plate fixation and describe the previously unreported complication of plantar necrosis. Medical records of 40 dogs that had been treated by tarsal arthrodesis with bone plate fixation were reviewed to determine the major and minor complications and the associated risk factors. The major complication rate was 32.5 per cent and the minor complication rate was 42.5 per cent. Pantarsal arthrodeses had a higher major complication rate than partial tarsal arthrodeses. Plantar necrosis was the most common major complication and occurred in 15 per cent of cases. Plantar necrosis occurred more frequently when a bone plate was applied to the medial aspect of the hock, and only occurred in cases where tarsometatarsal joint arthrodesis was performed. Plantar necrosis is a catastrophic complication that may be associated with injury to the dorsal pedal artery or perforating metatarsal artery. Application of a bone plate to the medial aspect of the hock should be performed with care during tarsal arthrodesis, particularly where the tarsometatarsal joint is debrided of cartilage. Strict attention to surgical technique and proper postoperative coaptation is critical to reduce the potential for complications with tarsal arthrodesis.

A morphometric study on the cross–sections of the scapular spine in dogs

In cases of unstable scapular body fractures, the base of the scapular spine is one of the sites where there is adequate bone for the application of plate fixation in dogs. In this type of fixation, the amount of bone is an important factor with regard to the holding power of the screw from the biomechanical viewpoint. Therefore, the aim of this paper is to present the detailed quantitative features of the sectional area of the scapular spine in dogs. A total of 28 scapulas from 14 dogs were used, and each was divided into 10 equal slices The height of the scapular spine, depths of the supra-spinous and infraspinus fossae were measured from the scanned images with the aid of a computer program. The results showed that the depth of the supraspinous fossa was greater in the ventral half of the spine, while the depth of the infraspinous was greater in the dorsal half. The differences between the depths of the two fossae were noticeable in the ventral half of the scapular spine.

The use of Ellis pins (negative profile tip-threaded pins) in external skeletal fixation in dogs and cats

SummaryThe Ellis pin is commonly used in external skeletal fixators (ESFs) but some authors suggest that this pin suffers from a high rate of failure. The purpose of this study was to look for complications associated with four different pin types, in particular pin breakage, as well as pin loosening, radiolucency around pins and pin tract discharge. Fifty consecutive cases which had an ESF applied using Ellis pins were identified. Radiographs and case records were used to record case details, ESF design, duration of fixation, pin types used, and complications. Records from 31 dogs and 17 cats were examined (2 animals were removed from the study because of incomplete follow-up). There were 21 Type I, 7 Type I with a tied-in IM pin, 2 modified Type I, 2 modified Type I with a tied-in IM pin and 16 modified Type II ESFs. 160 Ellis pins, 30 centrally threaded positive profile pins, 4 end threaded positive profile pins and 46 smooth pins were used. Complications relating to one or more of the pins were seen in 65% of the fixators. None of the pins broke. There was a significant association between individual pin type and the number of pins showing loosening (p = 0.002) or radiolucency (p = 0.006), but not a significance in the association between pin type and discharge (Chi-Square test). When each pin was compared against each other pin, smooth pins were significantly more likely to be loose than Ellis pins (p &lt;0.001), and centrally threaded positive profile pins were significantly more likely to result in radiolucency than Ellis pins (p = 0.01), using a Chi-square test. There was not any significant association between any other pin types for any complication using a Fisher’s Exact test. The study demonstrates that Ellis pins, when inserted correctly, are not at any greater risk of failure than other pin types, and that fewer complications may be associated with them than other pin designs.

A Biomechanical Evaluation and Assessment of the Accuracy of Reduction of Two Methods of Acetabular Osteotomy Fixation in Dogs

To compare the accuracy of reduction, biomechanical characteristics, and mode of failure of two methods of acetabular osteotomy repair. Acetabular osteotomies were created in 16 paired hemipelves and stabilized with a screw/wire/polymethylmethacrylate composite fixation technique (SWP) or a 2-mm veterinary acetabular plate (VAP). Eight intact hemipelves were used as controls. Twelve canine cadavers. Accuracy of osteotomy reduction was evaluated grossly and by measurement of articular incongruencies formed in polyvinylsiloxane impression casts. Acetabula were loaded in modified bending until failure using a universal testing machine. Data from load-deformation curves were used to determine the biomechanical characteristics of the repaired and intact acetabula. Mode of failure was evaluated grossly and radiographically. Osteotomy reduction was superior in acetabula stabilized with SWP. Mean values +/- standard deviation for load at failure and stiffness of the intact acetabula were 2,796 +/- 152.9 N and 267.5 +/- 61.9 N/mm. Corresponding values for SWP and VAP were 1,192 +/- 202.7 N and 136.3 +/- 76.5 N/mm, and 1.100.5 +/- 331.6 N and 110.0 +/- 51.3 N/mm, respectively. The mean load at failure and stiffness of intact acetabula was significantly greater than acetabula stabilized with SWP or VAP. There was no significant difference between SWP and VAP for load at failure or stiffness. Failure of acetabula stabilized with SWP occurred by fracture of the polymethylmethacrylate and ventrolateral bending of the wires. Acetabula stabilized with VAP failed by ventrolateral twisting of the plate and bending of the caudal screws. SWP and VAP provide comparable rigidity, however, the SWP facilitates more accurate osteotomy reduction. These findings support the use of the SWP technique as an alternative method of acetabular fracture repair.

Evaluation of hydroxyapatite-coated screws for lumbar spine fixation in dogs

To evaluate the firmness of fixation of hydroxy-apatite(HA)-coated screws used for spinal fixation, research has been done to measure the force required to pull out such screws. However, despite its importance, no research has been done to evaluate the twisting force necessary to loosen the screw. With regard to the twisting force, we evaluated the effects of HA coating on securing titanium alloy screws to canine lumbar vertebrae. Bonding of HA-coated (HA) screws and titanium alloy (Diapason; D) screws to the bone was examined serially over a period of 24 weeks by measuring the torque required to loosen the screws after a period of fixation and by histological examination of the screw-bone interface. Twelve screws (six screws of each type) were used in each of seven mongrel dogs, on each side of the lumbar vertebrae (L1-L6). The torque required to loosen D screws 6 weeks after insertion was three times higher than that used at time 0. With the HA screw, the torque at 2 and 6 weeks was four and six times higher, respectively, than that at time 0. Eight weeks after insertion, the torque for the HA screw was 2.3 times greater than that for the D screw (P < 0.01). Histological examination showed direct binding of HA to the bone early after insertion. Our results indicate that HA screws are firmly fixed in bone within a short period after insertion into the vertebra. In the clinical setting, the use of HA screws for spinal fixation may produce stable spine fixation within a short period after operation.

Spinal Fixation in Dogs Using Steinmann Pins and Methylmethacrylate

Steinmann pins and methylmethacrylate were used to stabilize 17 vertebral fractures or luxations and one unstable congenital spinal deformity in 18 dogs of a wide range of ages and body weights. Of 12 dogs available for follow‐up examination (4–43 months), 10 were normal or only mildly ataxic, and two were ambulatory but severely ataxic. Five dogs died or were euthanized in the early postoperative period, but none of the deaths could be attributed to the technique. Uncommon complications associated with this fixation technique were pin migration and wound infection.

The effects of intramedullary methylmethacrylate and reaming on the circulation of the tibia after osteotomy and plate fixation in dogs.

The effects of intramedullary methylmethacrylate and reaming on the circulation of the tibia after osteotomy and plate fixation in dogs.