Single institution retrospective study evaluating the frequency of implant removal and associated risk factors following open fracture fixation in 80 cases (2010-2020).

BACKGROUND: Open fractures occur commonly in small animals and are characterised by contamination of the fracture site. While never quantified, it is believed that open fractures stabilised with internal implants are at a higher risk for requiring explantation. This retrospective study determines the frequency and risk factors for explantation following use of internal fixation. Medical records of client-owned dogs and cats with an open fracture, between 2010 and 2020 stabilised using internal implants, were included. Data retrieved included signalment, cause and characterisation of the fracture, comorbidities, preexisting infections, and all details related to anesthesia and surgery. Pre-, Peri- and post-operative antibiotic use were detailed. All cases were followed to clinical union. Postoperative complications, including requirement for implant removal were recorded and classified as major or minor. Associations between potential risk factors and need for explantation were assessed. RESULTS: Of 80 cases, 72 (90%) were dogs and eight (10%) cats. Major complications were encountered in 23 (28.75%) cases and minor complications in 16 (20%) cases. Explantation was performed in 17 cases (21.25%). Out of 72 dogs, 13 required explantation (18%) whereas four of the eight cats needed implants removed (50%). Only diagnosis of postoperative infection was associated with an increased risk of explantation (RR 2.77; 95% CI 1.25; 6.15; p = 0.045). CONCLUSION: Approximately 1 in 5 open fractures stabilised using internal fixation can be anticipated to require explantation, with cats potentially being at a higher risk than dogs. Cases diagnosed with postoperative infection are at a higher risk for requiring implant removal.

Biomechanical Comparison of Cortical Lag Screws and Cortical Position Screws for Their Generation of Interfragmentary Compression and Area of Compression in Simulated Lateral Humeral Condylar Fractures.

OBJECTIVE: The aim of this study was to compare the interfragmentary compressive force and area of compression generated by cortical screws inserted as either a lag screw or position screw in simulated lateral humeral condylar fractures. STUDY DESIGN: Ex vivo biomechanical study. MATERIALS AND METHODS: Thirteen pairs of cadaveric humeri from skeletally mature Merinos with simulated lateral humeral condylar fractures were used. Pressure sensitive film was inserted into the interfragmentary interface prior to fracture reduction with fragment forceps. A cortical screw was inserted as a lag screw or a position screw and tightened to 1.8Nm. Interfragmentary compression and area of compression were quantified and compared between the two treatments groups at three time points. RESULTS: After fracture reduction using fragment forceps (Time point 1: T1), there was no significant difference in interfragmentary compression and area of compression between the two treatments. A combination of fragment forceps and a cortical screw inserted as a lag screw (Time point 2: T2) produced significantly greater interfragmentary compression and area of compression compared with the same screw inserted as a positional screw. After removal of the fragment forceps, leaving only the cortical screw (Time point 3: T3), both the interfragmentary compression and area of compression remain significantly greater in the lag screw group. CONCLUSION: Lag screws generate a greater force of compression and area of compression compared with position screws in this mature ovine humeral condylar fracture model.

Repair of a calcaneal fracture with a combination of internal and external fixation in a calf.

A 6-day-old male Japanese Black calf presented with a transverse fracture of the left calcaneus. In calcaneal fractures, traction of the gastrocnemius muscle causes substantial displacement of the proximal fracture fragment; therefore, external fixation alone is prone to failure of fusion or deformed fusion. Furthermore, internal fixation alone may result in refracture due to the high load on the implant. Therefore, internal and external fixation were used to treat the fracture. Bone fusion was observed on postoperative day 50; the wire was removed on postoperative day 90. Radiographic examination at 4 months postoperatively revealed that the bone had fused in normal alignment. Therefore, a good prognosis can be expected for calcaneal fractures treated with combined internal and external fixation.

Accuracy of pin placement in the canine thoracolumbar spine using a free-hand probing technique versus 3D-printed patient-specific drill guides: An ex-vivo study.

OBJECTIVE: To compare pin placement accuracy, intraoperative technique deviations, and duration of pin placement for pins placed by free-hand probing (FHP) or 3D-printed drill guide (3DPG) technique. SAMPLE POPULATION: Four greyhound cadavers. METHODS: Computed tomography (CT) examinations from T6-sacrum were obtained for determination of optimal pin placement and 3DPG creation. Two 3.2/2.4-mm positive profile pins were inserted per vertebra, one left and one right from T7-L7 (FHP [n = 56]; 3DPG [n = 56]) by one surgeon and removed for repeat CT. Duration of pin placement and intraoperative deviations (unanticipated deviations from planned technique) were recorded. Pin tracts were graded by two blinded observers using modified Zdichavsky classification. Descriptive statistics were used. RESULTS: A total of 54/56 pins placed with 3DPGs were assigned grade I (optimal placement) compared with 49/56 pins using the FHP technique. A total of 2/56 pins placed with 3DPGs and 3/56 pins using the FHP technique were assigned grade IIa (partial medial violation). A total of 4/56 pins placed using the FHP technique were assigned grade IIIa (partial lateral violation). No pins were assigned grade IIb (full medial violation). Intraoperative technique deviations occurred with 6/56 pins placed using the FHP technique and no pins with 3DPGs. Overall, pins were placed faster (mean ± SD 2.6 [1.3] vs. 4.5 [1.8] min) with 3DPGs. CONCLUSIONS: Both techniques were accurate for placement of spinal fixation pins. The 3DPG technique may decrease intraoperative deviations and duration of pin placement. CLINICAL RELEVANCE: Both techniques allow accurate pin placement in the canine thoracolumbar spine. The FHP technique requires specific training and has learning curve, whereas 3DPG technique requires specific software and 3D printers.

Biomechanical comparison of one pin versus two pin fixation in a canine tibial tuberosity avulsion fracture model.

OBJECTIVE: To determine whether one larger or two smaller diameter pins used for tibial tuberosity avulsion fracture (TTAF) stabilization provides greater axial tensile strength and stiffness when subjected to monotonic mechanical load to failure in normal skeletally mature canine cadavers. STUDY DESIGN: Paired ex vivo biomechanical study. SAMPLE POPULATION: Eleven pairs of adult cadaveric dog tibias. METHODS: Twenty-two tibias from 11 dogs were collected to model a TTAF. Each limb of a pair was randomly assigned a one or two-pin fixation. Tibias were subjected to monotonic, axial load to failure. Fixation stiffness, strength, and pin insertion angles were analyzed with parametric testing. Significance was set at p < .05. RESULTS: The mean strength of the single-pin fixation was 426.2 ± 50.5 N compared to two-pin fixation at 639.2 ± 173.5 N (p = .003). The mean stiffness of the single-pin fixation was 57.3 ± 18.7 N/mm and the two-pin fixation was 71.7 ± 20.5 N/mm (p = .029). The normalized ratio between one and two-pin fixation had a mean stiffness of 68% ± 25.8% and strength of 82.8% ± 24.6%. CONCLUSIONS: In an ex vivo cadaveric TTAF model, vertically aligned two-pin fixation offers greater strength and stiffness when compared to a single-pin fixation. CLINICAL SIGNIFICANCE: When repairing TTAF, surgeons should aim to apply two vertically aligned pins rather than a single pin for greater strength and stiffness.

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.

Feline Femoral Fracture Fixation: What are the options?

PRACTICAL RELEVANCE: The femur is the most commonly fractured bone in cats. Femoral fractures usually result from high-velocity trauma such as a road traffic accident or fall from a height and, as such, are associated with a wide variety of concurrent injuries. The initial focus of treatment should always be on assessment and stabilisation of the major body systems. Once any concurrent injuries have been addressed, all femoral fractures need surgical stabilisation, with the notable exception of greenstick fractures in very young cats, which can heal with cage rest alone. A number of different surgical options are available depending on the fracture type, location, equipment, surgeon experience and owner finances. CLINICAL CHALLENGES: Femoral fractures can vary hugely in complexity and the small size of feline bones can limit the choice of implants. Furthermore, cats can present unique challenges in the postoperative period due to their active nature and the limited means to control their exercise level. AUDIENCE: This review is aimed at general and feline-specific practitioners who have some experience of feline orthopaedics, as well as those simply wishing to expand their knowledge. AIMS: The aim of this review is to help clinicians assess, plan and manage feline femoral fractures. It provides an overview of diagnostic imaging and a discussion of a range of suitable surgical options, including the principles of different types of fixation. It also highlights cat-specific issues, approaches and implants pertinent to the management of these cases. EVIDENCE BASE: A number of original articles and textbook chapters covering many aspects of femoral fractures in cats and dogs have been published. Where possible, this review draws on information from key feline research and, where necessary, extrapolates from relevant canine literature. The authors also offer practical guidance based on their own clinical experience.

Influence of screw head diameter on ex vivo fixation of equine lateral condylar fractures with 5.5 mm cortical screws.

OBJECTIVE: To determine the influence of screw head diameter on equine condylar fracture fixation with 5.5 mm cortical screws. STUDY DESIGN: Ex vivo, biomechanical study, blinded, matched-pair design. SAMPLE POPULATION: Fifteen pairs of equine third metacarpal (MC3) bones. METHODS: Lateral condylar fractures were simulated by parasagittal osteotomies and repaired pairwise by 2 × 5.5 mm cortical screws of 8 mm (standard) or 10 mm (modified) head diameter. Interfragmentary compression at maximum screw insertion torque was measured. The instrumented specimens were pairwise stratified for biomechanical testing under the following modalities (n = 5): (1) screw insertion torque to failure, (2) quasi-static axial load to failure, and (3) cyclic axial load to 2 mm displacement followed by failure. Tests (1) and (2) were analyzed for yield, maximum, and failure torque/angle and load/displacement, respectively. Number of cycles to 2 mm displacement and failure was assessed from test (3). RESULTS: Maximum insertion torque was greater, and failure angle smaller, when constructs repaired with modified screws were tested (8.1 ± 0.5 vs. 7.4 ± 0.5 Nm; P = .0047 and 550 ± 104 vs. 1130 ± 230; P = .008). Axial yield (7118 ± 707 vs. 5740 ± 2267 N; P = .043) and failure load (12 347 ± 3359 vs. 8695 ± 2277 N; P = .043) were greater for specimens repaired with modified screws. No difference was detected between constructs in the number of cycles to 2 mm displacement. CONCLUSION: Condylar MC3 osteotomies repaired with modified 5.5 mm cortical screws sustained greater maximal hand torque insertion, smaller insertion failure angle and 1.4 fold greater quasi-static failure forces than constructs repaired with standard 5.5 mm screws. CLINICAL SIGNIFICANCE: Use of modified screws with larger heads may improve the fixation of condylar fractures in horses. These results provide evidence to justify clinical evaluation in horses undergoing fracture repair.

Analysis of feline humeral fracture morphology and a comparison of fracture repair stabilisation methods: 101 cases (2009-2020).

OBJECTIVES: The aims of this study were to describe the type, presentation and prognostic factors of feline humeral fractures over a 10-year period and to compare three stabilisation systems for feline humeral diaphyseal fractures. METHODS: In total, 101 cats with humeral fractures presenting to seven UK referral centres between 2009 and 2020 were reviewed. Data collected included signalment, weight at the time of surgery, fracture aetiology, preoperative presentation, fixation method, surgical details, perioperative management and follow-up examinations. Of these cases, 57 cats with humeral diaphyseal fractures stabilised using three different fixation methods were compared, with outcome parameters including the time to radiographic healing, time to function and complication rate. RESULTS: The majority of the fractures were diaphyseal (71%), with only 10% condylar. Of the known causes of fracture, road traffic accidents (RTAs) were the most common. Neutered males were over-represented in having a fracture caused by an RTA (P = 0.001) and diaphyseal fractures were significantly more likely to result from an RTA (P = 0.01). Body weight had a positive correlation (r = 0.398) with time to radiographic healing and time to acceptable function (r = 0.315), and was significant (P = 0.014 and P = 0.037, respectively). Of the 57 humeral diaphyseal fractures; 16 (28%) were stabilised using a plate-rod construct, 31 (54%) using external skeletal fixation and 10 (18%) using bone plating and screws only. Open diaphyseal fractures were associated with more minor complications (P = 0.048). There was a significant difference between fixation groups in terms of overall complication rate between groups (P = 0.012). There was no significant difference between fixation groups in time to radiographic union (P = 0.145) or time to acceptable function (P = 0.306). CONCLUSIONS AND RELEVANCE: All three fixation systems were successful in healing a wide variety of humeral diaphyseal fractures. There was a significantly higher overall complication rate with external skeletal fixators compared with bone plating; however, the clinical impact of these is likely low.

The use of circular and hybrid external skeletal fixation systems to repair open tibial fractures in large ruminants: a report of six clinical cases.

A prospective clinical study consisting of six bovines (200-300 kg body weight) undergoing open tibial fractures was carried out, to evaluate the use of circular and hybrid external skeletal fixation (ESF) systems for open tibial fracture repair in large ruminants. The ESF systems consisting of 4 full rings (n = 2), 8 half-rings (n = 1), 2 full rings with 2 sidebars (n = 2) or 2 full rings with 4 sidebars (n = 1) were used to treat open tibial fractures. The healing progress of the animals was evaluated based on different clinical and radiographic examinations. The level of fracture reduction, alignment, and fixation ranged between satisfactory to adequate in all the animals. The fixators were well tolerated and maintained by the animals till the complete repair of the fracture. Adequate fracture healing with satisfactory functional recovery was observed in all the animals in about 3-4 months. The different designs of ESFs were found to provide adequate stability in open tibial fractures in animals weighing 200-300 kg. However, the fixators need to be evaluated in numerous clinical cases to establish their suitability in routine clinical settings.

Effects of the number and the position of transfixation pins in acrylic connecting bars.

Acrylic columns are commonly used in external skeletal fixators, especially for fracture management or trans-articular fixations. To the authors' knowledge, there are no studies demonstrating if the number or position of the transfixation pins influence the ultimate strength and stiffness of the acrylic column. The objective of this study was to evaluate the effects of the number and position of transfixation pins (concentric versus eccentric) on the strength and stiffness of acrylic columns placed in axial compression. We hypothesized that strength and stiffness of acrylic columns under axial compression would not be affected by the number or position of the transfixation pins through the column. Three different groups of 12 acrylic columns were constructed with 4, 6, and 8 pins. In each group, 6 columns were constructed with the pins placed concentrically and the remaining 6 columns with the pins placed eccentrically. Each column was then placed under axial compression using a biomechanical testing machine. No significant differences were observed in ultimate strength regarding the number or position of transfixation pins (P = 0.83 and P = 0.27, respectively). However, stiffness was significantly decreased for columns with 4 eccentric pins compared with columns with 6 and 8 eccentric pins (P < 0.01) and with columns with 4 concentric pins (P < 0.001). Although the effects of transfixation pins on the rigidity of acrylic columns do not appear to be clinically significant, these tests were performed only in compression and results might differ if complete external fixator systems are used with different models of testing. Future studies are recommended.

Les colonnes d'acrylique sont couramment utilisées dans les fixateurs externes, notamment pour la gestion des fractures ou les fixations transarticulaires. Selon les auteurs, aucune étude ne démontre si le nombre ou le positionnement des broches de transfixation influence la résistance ultime et la rigidité de la colonne d'acrylique. Les objectifs de cette étude étaient d'évaluer l'effet du nombre et du positionnement des broches de transfixation (concentriques versus excentriques) sur la résistance et la rigidité des colonnes d'acryliques placées en compression axiale. Nous avons émis l'hypothèse que la résistance et la rigidité des colonnes d'acryliques en compression axiale ne seraient pas affectées par le nombre ou le positionnement des broches de transfixation à travers la colonne. Trois groupes différents de douze colonnes acryliques ont été construits avec quatre, six, et huit broches. Dans chaque groupe, six colonnes ont été construites avec les broches placées concentriquement et les six colonnes restantes avec les broches placées de manière excentrique. Chaque colonne a ensuite été placée sous compression axiale à l'aide d'une machine de tests biomécaniques. Aucune différence significative n'a été observée pour la résistance ultime selon le nombre ou le positionnement des broches de transfixation (P = 0,83 et P = 0,27, respectivement). Cependant, la rigidité a été significativement diminuée pour les colonnes avec quatre broches excentriques par rapport aux colonnes avec six et huit broches excentriques (P < 0,01) et avec les colonnes avec quatre broches concentriques (P < 0,001). Bien que les effets des broches de transfixation sur la rigidité des colonnes acryliques ne semblent pas être cliniquement significatifs, ces tests ont été effectués uniquement en compression et les résultats pourraient différer si des systèmes complets de fixateurs externes sont utilisés avec différents modèles de test. De futures études sont recommandées.(Traduit par les auteurs).

Safe corridors for external skeletal fixator pin placement in feline long bones.

OBJECTIVES: External skeletal fixation is an established technique in cats for biological fixation of long bone fractures, stabilisation of the joints, and treatment of shearing injuries and angular deformities. As appropriate and accurate pin insertion is imperative for a successful outcome, knowledge of topographic anatomy and areas that are safe (safe corridors) for pin placement is integral to successful surgery. At present, however, safe corridors have not been determined fully in feline orthopaedics, with surgeons having to rely on knowledge based on canine orthopaedics. This study was performed to determine safe corridors for pin placement in feline long bones. METHODS: The limbs of six feline cadavers were frozen. Only limbs with no history of orthopaedic conditions were used. Transverse sections through the limbs were examined, and anatomical structures were determined in relation to the bone. These structures were compared with those of the contralateral limbs, which were dissected for topographic assessment. Safe corridors were defined as topographic areas where no vital structures, muscles or joints were present. RESULTS: Examination of the humerus revealed safe corridors at its proximal craniolateral aspect and on the medial and lateral humeral condyles. Safe corridors of the antebrachium were identified on the lateral aspect of the olecranon, the distal two-thirds of the medial antebrachium and the distal third of the lateral antebrachium. Safe corridors in the femur consisted of a small area lateral to and just below the major trochanter, and on the medial and lateral femoral condyles. Evaluation of the tibia revealed safe corridors on the medial aspect of the entire tibia, the cranial aspect of the proximal tibia on the tibial crest and the area just proximal to the lateral malleolus. CONCLUSIONS AND RELEVANCE: Safe corridors for pin placement during external skeletal fixation in feline limbs differed from those in canine limbs. Knowledge of canine anatomy may be inapplicable to pin placement in feline limbs undergoing external skeletal fixation.

Evaluation of a screw insertion landmark for a minimally invasive repair technique in induced bilateral sacroiliac luxation in feline cadavers.

OBJECTIVES: The aim of this study was to describe an alternative landmark for screw insertion into the body of the ilium with bilateral sacroiliac luxation in cats. METHODS: Seven cat cadavers with artificially induced bilateral sacroiliac luxation were used. The screw insertion point was determined using the caudal iliac crest and cranial acetabular rim. These two points make the first guideline; a second guideline ran perpendicular to the caudal iliac crest point. The screw insertion point was halfway along the second guideline across the ilium body. Surgery was performed in a minimally invasive manner using fluoroscopy. RESULTS: Postoperative radiographs and CT were performed. In the postoperative evaluation, the sacroiliac joint reduction percentage was almost 90% and there was no significant difference in pelvic canal diameter ratio before and after surgery. Screw depth/sacral width was >60% in all cadavers. On CT, the angle between the screw and sacrum wing was within the normal range of 96.24° to the left and 98.65° to the right, except in one case. CONCLUSIONS AND RELEVANCE: In previous studies, surgical repair was based on having an intact contralateral ilium. However, this method is not applicable to patients with bilateral sacroiliac luxation and is mostly performed using open reduction methods. The screw insertion point suggested in this study offers a potential alternative repair technique for patients with bilateral sacroiliac luxation.

Combined internal fixation and transarticular external skeletal fixation to treat traumatic patellar fractures in five dogs.

CASE HISTORY: Medical records of dogs (n = 5) that had been treated for patellar fracture with transarticular external skeletal fixation (TA-ESF) to augment internal fixation, at a single referral hospital in the United Kingdom between 2015 and 2017, were reviewed. CLINICAL FINDINGS AND TREATMENT: At presentation, two dogs had polar patellar fractures, two had comminuted fractures and one dog had a transverse fracture. The median age at the time of the surgery was 21 (min 8, max 132) months and the median body weight was 19.0 (min 8.3, max 28.6) kg. In all cases, TA-ESF (Type IA lateral triangulated or modified Type II) was used in combination with internal fixation with pins and/or orthopaedic wire, supported by nylon leader line (patella-to-tibia mattress suture) and/or absorbable suture in a locking loop and/or circum-patellar pattern. All cases had short-term (6-12 weeks) post-operative radiographic follow-up, which showed evidence of fracture healing in 2/5 cases. All TA-ESF were removed 6 or 7 weeks post-operatively and four dogs had minor complications related to TA-ESF. More than 2 years post-operatively, the owners of all dogs were contacted and questioned using the Liverpool Osteoarthritis in Dogs questionnaire regarding the mobility of their pet. Four of the five cases were re-examined to evaluate their long-term outcomes. Based on the results of goniometric measurement of stifle range of motion, subjective gait assessment and objective gait analysis with a pressure-sensitive walkway, all dogs showed a satisfactory outcome at the final follow-up. CLINICAL RELEVANCE: A combination of internal fixation and TA-ESF for stabilisation of traumatic patellar fractures is a valid treatment option. Further investigations with larger case numbers are necessary to evaluate success and complication rates.

Effect of Bidirectional Insertion of External Skeletal Fixation Pins on Axial Pullout Strength in Canine Cadaveric Bone.

OBJECTIVE: The aim of this study was to evaluate the effect of bidirectional insertion on axial pullout strength of tapered run out (TRO), traditional negative profile (TNP) and positive profile (PP) pins. STUDY DESIGN: Cadaveric adult canine tibiae were harvested. Tapered run out pins (Group 1) were inserted unidirectionally to the desired position; bidirectionally past the desired position, then withdrawn to the desired position (Group 2); and bidirectionally as described for Group 2, repeated twice (Group 3). Traditional negative profile pins (Group 4-6) and PP pins (Group 9-11) were placed in the same manner. Tapered run out (Group 7), TNP (Group 8) and PP pins (Group 12) were driven unidirectionally such that the shaft of the pin violated the cis-cortex. A servohydraulic testing machine extracted the pins and measured axial peak pullout strength. RESULTS: Positive profile pins had significantly greater pullout strength than TRO and TNP pins placed unidirectionally to the desired position. Method of insertion had no effect on peak pullout strength of TNP pins. TRO and PP pins inserted unidirectionally to the desired position had significantly greater peak pullout strengths than insertion bidirectionally or if the shaft of the pin violated the cis-cortex. CONCLUSION: The authors recommend that pins used for external skeletal fixation should be placed unidirectionally to the desired position with fluoroscopic guidance, intra-operative depth gauge measurements or measurements from preoperative radiographs. Repositioning pins results in loss of peak pullout strength with TRO and PP pins.

Description of and complications associated with reinforced, free-form external skeletal fixation for treatment of appendicular fractures in cats: 46 cases (2010-2019).

OBJECTIVE: To describe a modified technique for reinforced, free-form external skeletal fixation (rFF-ESF) of appendicular fractures in cats and identify factors associated with development of complications. ANIMALS: 46 cats with fractures repaired with rFF-ESF at Angell Animal Medical Center between 2010 and 2019. PROCEDURES: Medical records were reviewed for information on signalment, affected bone, fracture location and orientation, degree of comminution, severity (open vs closed), fixator type, number of fixation pins, use of an intramedullary pin (yes vs no), surgeon experience (staff surgeon vs surgical resident), anesthesia time, surgery time, perioperative antimicrobial administration, concurrent surgical procedures, intraoperative complications, postoperative alignment, whether fixator destabilization was performed, and time to complete fixator removal. Postoperative complications were recorded. RESULTS: 43 of the 46 (93%) cats had a successful outcome, with a median time to complete fixator removal of 8 weeks (range, 3 to 61 weeks). Twelve of the 46 (26%) cats had major (n = 3) or minor (9) complications. In univariable analyses, 4 factors were significantly associated with development of postoperative complications: body weight (OR for each 1-kg increase in weight, 1.8), tibial fracture (vs fracture of any other long bone; OR, 16), use of a type 2 fixator (vs a type 1 fixator; OR, 11), and use of destabilization (vs no destabilization; 7). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that rFF-ESF can be successfully used to stabilize a variety of appendicular fractures in cats. Further studies are required to compare rFF-ESF with other fracture fixation methods.

Patellar fractures in cats: Repair techniques and treatment decision-making.

PRACTICAL RELEVANCE: While feline patellar fractures are not commonly encountered in practice, they tend to be found more often in younger cats; no breed or sex predispositions are recognised. If there is no evidence of a traumatic aetiology, the cat may be suspected of having patellar fracture and dental anomaly syndrome (PADS). Patellar fractures are easy to diagnose on lateral radiographs and there are several different fracture types. The type of fracture, the age of the cat at fracture occurrence and whether there is suspicion of a pathological aetiology are all relevant when considering treatment technique. CLINICAL CHALLENGES: While some cats with patellar fractures will do well with conservative management, surgical treatment is often indicated and decision-making can be challenging. EVIDENCE BASE: Information and recommendations provided in this review are based on the literature and the author's own clinical experience. There are several publications on PADS, but there is limited evidence as to what the underlying cause of this condition is, and the best method for managing patellar fractures is still an area where more research is needed. AIM: This review aims to gather the papers, case series and case reports published over the past few decades in order to discuss how best to manage different types of patellar fractures.

Use of a circular fixator construct to facilitate closed reduction and percutaneous stabilization of a distal femoral physeal fracture in a dog.

Background: Fractures of the distal femoral physis are the most common physeal fracture sustained by skeletally immature dogs. Reduction and stabilization of these fractures can sometimes be achieved through closed reduction, primarily in fractures that are nominally displaced. Circular external fixator constructs have been used to assist in indirect, closed reduction of fractures at other anatomic locations in dogs and this report describes application of this method to reduce a displaced Salter-Harris type II fracture of the distal femur in a 1-year-old dog. Case Description: A 1-year-old female spayed Akita was referred for treatment of a Salter-Harris type II fracture of the right distal femur. The epiphyseal segment was laterally and slightly caudally displaced. Multiple attempts to manually reduce the fracture during surgery were unsuccessful, so a two-ring circular external fixator construct was applied to facilitate distraction and reduction. The construct was applied by placing a medial-to-lateral Kirschner wire in both the mid-femoral diaphysis and in the distal femoral epiphysis. Distraction of the construct provided sufficient separation of the fracture segments to facilitate near anatomic reduction. The fracture was stabilized with two percutaneously placed Steinmann pins placed in Rush fashion. Radiographic union was confirmed 5 weeks after surgery. The dog was not lame and was bearing more weight on the right pelvic limb, as assessed using force plate analysis, 9 months following surgery. Goniometric measurements of stifle range of motion and thigh muscle circumference were similar between the pelvic limbs. Conclusion: Application of a two-ring circular construct would appear to be useful to facilitate closed reduction and percutaneous stabilization of distal femoral physeal fractures.

Ex vivo comparison of standing and recumbent repair of incomplete parasagittal fractures of the first phalanx in horses.

OBJECTIVE: To assess suspensory ligament extensor branch location and fracture gap reduction with simulation of standing and recumbent cortical bone screw repair of experimental incomplete parasagittal proximal phalanx (P1) fractures. STUDY DESIGN: Controlled laboratory study. SAMPLE POPULATION: Twenty equine cadaver forelimbs. METHODS: Simulated fractures were repaired twice in random order. A proximal cortical bone screw was placed in lag fashion with the limb unloaded (simulated recumbent repair) and loaded to 38% of body weight (range, 375-568 kg; simulated standing repair). Changes in fracture gap width were assessed on computed tomography (CT) images and with intraplanar force-sensitive resistors measuring voltage ratios (V△ ) between loaded recumbent (R-1) and standing repair simulations (R-2). Extensor branch borders were determined relative to implant position and sagittal P1 width on transverse CT images. P ≤ .05 was considered significant. RESULTS: Standing repair simulation-associated fracture gaps were not wider than in R-1 while controlling for confounding factors (loading weight, implant position, or animal age; P > .7, repeated-measures analysis of variance). Voltage ratio data associated with R-2 were not smaller than with R-1 (mean difference, 0.002 ± 0.052; one-sided Wilcoxon signed-rank test, P = .27). More of P1 width was approachable palmar to extensor branches when limbs were loaded (0.804 ± 0.314 cm) vs unloaded (0.651 ± 0.31 cm; paired Student's t test, P < .001). CONCLUSION: Simulated standing repair was not associated with inferior fracture reduction compared with loaded simulations of recumbent repairs. Limb loading affected extensor branch location relevant to implant positioning. CLINICAL SIGNIFICANCE: Unloading during standing repair of incomplete parasagittal proximal P1 fractures may not be required to optimize fracture reduction.