Management of 49 antebrachial and crural fractures in dogs using circular external fixators

Linear external skeletal fixation applied in minimally invasive fashion for stabilization of nonarticular tibial fractures in dogs and cats

OBJECTIVE

The objective of this study was to evaluate the use of linear external skeletal fixation (ESF) applied using minimally invasive techniques in dogs and cats.

STUDY DESIGN

Retrospective study.

ANIMALS

Forty-nine dogs and 6 cats.

METHODS

Medical records of cases with nonarticular tibial fractures, repaired using linear ESF at a single academic institution between July 2010 and 2020, were reviewed. All records of cases that had nonarticular tibial fractures repaired using linear ESF were included. Information was collected regarding signalment, surgical procedures performed, perioperative care, radiographic evaluation, and postoperative complications.

RESULTS

Intraoperative imaging was used in 40/55 (72%) of cases. Tibal plateau angle (TPA), tibial mechanical medial proximal and distal tibial angles (mMPTA and mMDTA, respectively) were not affected by intraoperative imaging (P = .344, P = .687, P = .418). A total of 22 (40%) complications occurred. Of these, 18 were considered minor and 4 were considered major. Open fractures had more major complications than closed fractures (P = .019). All fractures reached radiographic union of the fracture. The mean ± SD time to external fixator removal was 71 ± 48 days.

CONCLUSION

Linear ESF applied using minimally invasive techniques with or without intraoperative imaging was an effective treatment for nonarticular tibial fractures.

CLINICAL SIGNIFICANCE

Closed application of linear ESF should be considered as a minimally invasive option for stabilizing nonarticular tibial fractures.

THE TREATMENT OF DISTAL FEMORAL FRACTURES OF CATS USING HYBRID EXTERNAL FIXATOR: TEN CASES (2018-2020)

In this research, the clinical and radiological findings after the treatment of distal femoral fractures in cats using hybrid external fixator were evaluated. The research material consisted of totally 10 cats with different ages, races and sexes that were clinically diagnosed with femoral fracture. Hybrid external fixators configured by both circular and linear fixators were used as osteosynthesis materials in the study. Two cases with closed fractures were applied with closed reduction and external fixation methods whereas 8 cases diagnosed with open fracture or excessive dislocation underwent limited open reduction and external fixation. The radiological examination findings revealed that fracture consolidation started on the postoperative 7th and 10th days in 9 and 1 cases, respectively. Bone healing was completed (formation of osseous callus was detected) in 4, 5 and 6 weeks in 2, 2 and 6 cases, respectively. The fixators of all the patients were removed 1 week after completion of healing. In the study, soft tissue complications such as edema of the related extremity, mild pin-base infection and open fracture wound were determined in 3, 3 and 4 cases, respectively. However, these complications were found not to negatively affect the healing time of the fractures. As a consequence, it was concluded according to the data obtained from this study that distal femoral fractures in the cats within the age and weight range of the study can be successfully treated using hybrid external fixator method

Comparison between Areas of Bone Visualization Using Radiolucent Hybrid Fixator Frames and Graphically Simulated Metallic Frames: An Ex Vivo Study

The objective of this study is to evaluate the difference between the amount of bone visible with the superimposition of a radiolucent hybrid external fixator and a graphically simulated metallic frame. Eighteen frames were applied to eighteen bone specimens. The fracture area (FA), the radiolucent area (RLA) and the radiopaque area (ROA) inside the FA were calculated for each construct on both postoperative views. The ratio between the RLA and FA and between the ROA and FA was used to evaluate the amount of bone visible in the FA with a radiolucent and a radiopaque fixator, respectively. Finally, the areas of RLA and ROA were compared using the Wilcoxon test and Friedman test to evaluate the effect of the radiolucent material on the amount of bone visible. Differences were considered significant if p < 0.5. In every specimen p was <0.5. The amount of bone visible was significantly higher with the radiolucent frame compared to the radiopaque frame. Based on the results of this study, the use of radiolucent materials can be a valuable option for external fixation, in order to decrease the radiographic interference of the frame, allowing better assessment of fracture reduction and bone healing on postoperative radiographs.

SUCCESSFUL REPAIR OF ANTEBRACHIAL FRACTURES WITH EXTERNAL SKELETAL FIXATION IN THREE MACROPODS

Three captive macropods comprising three different species sustained unilateral antebrachial fractures. All fractures were assumed to be trauma related, although the specific circumstances surrounding each case was unknown. Each fracture was surgically repaired with type Ia (unilateral, monoplanar) external skeletal fixators, which were all removed approximately 3 mo postoperatively. Although each animal experienced at least one complication, all animals showed adequate bridging and remodeling at the fracture sites and had good-to-excellent return to normal function after fixator removal. This case series is the first to describe the successful repair of antebrachial fractures using external skeletal fixation in captive macropods and details some of the complications that can occur with postoperative management of captive animals.

Clinical outcomes of 119 miniature- and toy-breed dogs with 140 distal radial and ulnar fractures repaired with free-form multiplanar type II external skeletal fixation

OBJECTIVE

To report the clinical outcomes of miniature- and toy-breed dogs with primary and previously treated distal radial and ulnar fractures (RUF) treated with a free-form multiplanar type II external skeletal fixation (ESF).

STUDY DESIGN

Retrospective study.

ANIMALS

One hundred nineteen dogs with 140 distal RUF.

METHODS

Medical records (2003-2017) were reviewed for dogs weighing up to 7 kg that had been treated for distal RUF with a free-form multiplanar type II ESF. Data collected included signalment, fracture location and configuration, fracture reduction, intraoperative realignment, time to bone union and implant removal, duration of destabilization and postoperative splint, complications, and outcomes. Follow-up consisted of clinical and radiographic evaluation or telephone interview.

RESULTS

All fractures healed, with a median time of 60 days, and entire ESF was removed, with a median time of 89 days. Major complications occurred in four fractures: premature pin loosening, elbow subluxation, osteomyelitis, and delayed union. Minor complications occurred in 52 fractures (61 events). All dogs had a successful return to normal limb function at final follow-up (median, seven months; range, 2-97).

CONCLUSION

All primary and previously treated distal RUF in miniature- and toy-breed dogs healed and allowed return to normal function after fixation with a free-form multiplanar type II ESF.

CLINICAL SIGNIFICANCE

The free-form multiplanar type II ESF provides an alternative for minimally invasive fixation of distal RUF in miniature- and toy-breed dogs that facilitates fracture reduction, intraoperative realignment, adequate initial fixation stability, destabilization, and implant removal.

Impact of fixation method on postoperative complication rates following surgical stabilization of diaphyseal tibial fractures in cats

Objectives: To compare the complication rate between open reduction and internal fixation (ORIF) and external skeletal fixation (ESF) for feline diaphyseal tibial fractures.

Methods: In a retrospective study spanning a 10 year period, 57 feline tibial fractures stabilized via ESF or ORIF were included for analysis and complication rates were compared between the two methods.

Results: In the overall study population, 23 (40.4%) cases suffered complications (9 major, 20 minor, 6 with both major and minor). All of the major complications occurred in the ESF group. Complications were more common in cats with ESF (50.0%) while only one (7.7%) of the ORIF cases suffered complications (OR 12.0 [CI: 2.09; 228.10], p = 0.02). Use of postoperative antibiotic medications was identified as a confounder. After adjusting for confounding, stabilization using ESF remained associated with a higher risk of complications (OR = 13.71 [CI: 2.18; 274.25], p = 0.02). Cats with ESF had a longer duration of follow-up (15.6 weeks; 95% CI: 13.0; 18.3) compared to ORIF (9.5 weeks; 95% CI: 6.4; 12.7) (p = 0.003), and a higher number of revisits (mean 3.0; 95% CI: 2.4; 3.6) than the ORIF group (mean 1.6; 95% CI: 0.9; 2.3) (p = 0.002).

Clinical significance: This study demonstrates a significant difference in complication rates between the methods of stabilization, with ESF resulting in a significantly higher complication rate compared to ORIF. Based on these results, it may be prudent to select ORIF for stabilization of feline tibial fractures wherever practical.

Treatment of fractures of the distal radius and ulna in toy breed dogs with circular external skeletal fixation: a retrospective study

Objective: To evaluate the effectiveness of circular external skeletal fixation (CESF) in treating fractures of the distal radius and ulna in toy breed dogs, and to document the type and frequency of complications associated with this technique.

Methods: The medical records of small breed dogs with fractures of the distal radius and ulna admitted to the University of Turin and to the Clinica Ferretti between 2002 and 2009 were retrospectively reviewed. The criteria for inclusion of cases in the study were: body weight of 5 kg or less, transverse or short oblique fracture of the distal third of the radius and ulna, no previous repair attempts, and treatment with CESF as the sole method of fixation.

Results: Twenty fractures in 16 dogs satisfied the criteria for inclusion into this study. No signs of infection or failure of fixation were detected in any case. Mean frontal plane alignment was 4.7° ± 2.7° and mean sagittal plane alignment was 12.7° ± 7.2°. Postoperative complications occurred in one patient. All fractures achieved union. Mean time until radiographic evidence of a bridging callus and subsequent implant removal was 71 days (range: 30–120).

Conclusions: The results of this study support the use of CESF for treatment of fractures of the distal radius and ulna in toy breed dogs as an alternative to other methods of fracture fixation. However, this technique requires a series of follow-up examinations to evaluate the stability of the apparatus, the soundness of the wires and to determine the appropriate time for implant removal.

Comparison of the axial stiffness of carbon composite and aluminium alloy circular external skeletal fixator rings

Objectives: The purpose of this study was to compare the axial stiffness of aluminium alloy and carbon composite single-ring constructs.

Methods: Single-ring constructs were made with rings of different material compositions (aluminium alloy and carbon composite), diameters (55 mm, 85 mm, and 115 mm), and thicknesses (6 mm for the single-ring, 12 mm for the double-ring) with all other components remaining constant. Stiffness of each construct was determined under loading in axial compression with a materials testing machine. The axial stiffness of each group was compared using a three-factor factorial analysis of variance investigating all main effects and interactions between ring diameter, ring thickness, and ring material composition; p <0.05 was considered significant.

Results: Carbon composite constructs were 16-55% as stiff as corresponding aluminium alloy constructs. Within each combination of ring material composition and ring diameter, stiffness did not significantly increase when the ring thickness was doubled. Within each combination of ring material composition and ring thickness, stiffness significantly decreased with increased ring diameter.

Clinical significance: Aluminium alloy rings were found to be significantly stiffer than carbon composite rings. Although the carbon composite rings were considerably less stiff, clinical recommendations cannot be made from a single-ring in vitro analysis. Further studies are needed to evaluate the behaviour of these rings in vivo.

Postoperative complications associated with external skeletal fixators in cats

OBJECTIVES

The objective of this study was to quantify complications associated with external skeletal fixators (ESFs) in cats and to identify potential risk factors.

METHODS

A retrospective review of medical records and radiographs following ESF placement was performed.

RESULTS

Case records of 140 cats were reviewed; fixator-associated complications (FACs) occurred in 19% of cats. The region of ESF placement was significantly associated with complication development. Complications developed most frequently in the femur (50%), tarsus (35%) and radius/ulna (33%). Superficial pin tract infection (SPTI) and implant failure accounted for 45% and 41% of all FACs, respectively. SPTI occurred more frequently in the femur, humerus and tibia, with implant failure more frequent in the tarsus. No association between breed, age, sex, weight, fracture type (open vs closed), ESF classification, number of pins per bone segment, degree of fracture load sharing, and the incidence or type of FAC was identified. No association between region of placement, breed, age, sex, weight, fracture type (open vs closed), ESF classification, number of pins per bone segment, fracture load sharing and the time to complication development was identified.

CONCLUSIONS AND RELEVANCE

Complication development is not uncommon in cats following ESF placement. The higher complication rate in the femur, tarsus and radius/ulna should be considered when reviewing options for fracture management. However, cats appear to have a lower rate of pin tract infections than dogs.

Radiographic distortion artifact of circular external fixators

Circular external fixators are commonly used to surgically treat a variety of orthopedic conditions. However, distortion artifact may mislead the radiographic interpreter as to the true anatomic location of the transfixing wires and either negatively impact patient healing or lead to unnecessary procedures. Distortion is due to unequal magnification of different parts of an object. The purpose of this study was to assess distortion of three circular external fixator apparatuses with the transfixing wires at 30, 60, and 90°. Distortion was greatest with all three apparatuses at 10° of rotation from parallel to the central X-ray beam. When comparing distortion between the three apparatuses, distortion was greatest with the transfixing wires at 30°. The study authors concluded that distortion artifact is most severe when the transfixing wires are at smaller angles and when they are farther from the X-ray table. The circular external fixator should be placed in the center of, and parallel to, the primary X-ray beam and as close to the table as possible to reduce/prevent distortion artifact and possible radiographic misinterpretation of transfixing wire location.

Evaluation of the accuracy of a veterinary dynamometric wire tensioner

OBJECTIVES

The purpose of this study was to determine the accuracy of a commonly used veterinary wire tensioner.

METHODS

Wire tension was measured using a load cell after each of five tensioners were used to tension each of six wires to the 66, 84, and 118 mm ring settings in an adjustable custom testing fixture. Each tensioner then experienced simulated aging and testing was repeated. Percentage error was calculated for each ring size, before and after tensioner aging. Measured tension values were compared to manufacturer reported tension values for each ring size using a one-sample two-way t-test; p <0.05 was considered significant.

RESULTS

Compared to the manufacturer reported values, measured wire tension values were significantly lower for 66 mm and 84 mm rings and significantly higher for 118 mm rings, before and after simulated aging. Mean wire tension values did not significantly differ between individual wire tensioners.

CLINICAL SIGNIFICANCE

The tensioners tested achieved significantly different wire tension values than those reported by the manufacturer. This discrepancy could lead to under-tensioning and allowing excessive movement at a fracture site or over-tensioning, leading to wire breakage. We recommend tensioning wires at least to the recommended line on the device for 66 mm and 84 mm rings and at most to the recommended line for 118 mm rings. Further studies are needed to evaluate other veterinary wire tensioners and to develop a calibration method for these devices in practice.

Evaluation of sixty-eight cases of fracture stabilisation by external hybrid fixation and a proposal for hybrid construct classification

Background

Hybrid external fixation (HEF) is an emerging technique for fracture stabilization in veterinary orthopedics, but its use has been reported in few papers in the veterinary literature. The linear and circular elements that form hybrid fixators can be connected in a very high number of combinations, and for this reason just referring to HEF without any classification is often misleading about the actual frame structure. The aim of this study was to retrospectively evaluate fracture stabilization by HEF in 58 client-owned dogs and 8 cats, and to extend the already existing classification for hybrid constructs to include all frame configurations used in this study and potentially applicable in clinical settings. Animal signalment, fracture classification, surgical procedure and frame configuration were recorded. Complications, radiographic, functional and cosmetic results were evaluated at the time of fixator removal.

Results

Sixty-eight fractures in 58 dogs and eight cats were evaluated. Two dogs had bilateral fractures. Fifty-one percent were radio-ulna, 34% tibial, 9% humeral, 3% femoral and 3% scapular fractures. One ring combined with one or two linear elements was the most widely employed configuration in this case series. Radiographic results at the time of frame removal were excellent in 59% of the cases, good in 38% and fair in 3%, while functional and cosmetic results were excellent in 69% of the cases, good in 27% and fair in 4%.

Conclusions

HEF is a useful option for fracture treatment in dogs and cats, particularly for peri and juxta-articular fractures. It can be applied with a minimally invasive approach, allows adjustments during the postoperative period and is a versatile system because of the large variety of combinations that can fit with the specific fracture features. The classification used enables to determine the number of linear and circular elements used in the frame.

Treatment of antebrachial and crural septic nonunion fractures in dogs using circular external skeletal fixation: a retrospective study

OBJECTIVE

To evaluate the outcome of treatment of antebrachial and crural septic non-union fractures in dogs using circular external skeletal fixation (CESF), and to document the type and frequency of complications associated with this technique.

METHODS

The medical records of all dogs with infected antebrachial and crural non-union fractures treated using the methods of Ilizarov at the Department of Animal Pathology of the University of Turin between 2006 and 2011 were retrospectively reviewed. Only dogs in which radiographic and clinical assessment were available at the time of CESF removal were included in the study.

RESULTS

Twenty-three dogs met the inclusion criteria. Twenty nonunion fractures treated with CESF healed and three did not. The latter three cases underwent amputation of the affected limb. In the 20 dogs that achieved bone union, six had minor complications and five had major complications. The mid-term outcome was judged to be excellent (n = 11), good (n = 6), fair (n = 2), or poor (n = 4).

CONCLUSIONS

The results of this study support the use of CESF for the management of antebrachial and crural septic nonunion fractures in dogs. Union was achieved in the majority of dogs and the complication rate was acceptable, considering the severity of the nonunion fractures that were managed in this fashion.