Management of feline tibial diaphyseal fractures using orthogonal plates performed via minimally invasive plate osteosynthesis

Biomechanical analysis of orthogonal and unilateral locking plate constructs in a fracture gap model

OBJECTIVE

To compare unilaterally plated (UP) constructs and orthogonally plated (OP) constructs of differing sizes (3.5 mm + 2.0 mm locking plates [OP2.0], 3.5 mm + 2.4 mm locking plates [OP2.4] and 3.5 mm + 3.0 mm locking plates [OP3.0]) under cyclic and static axial compression load to failure testing using a fracture gap model.

STUDY DESIGN

In vitro experimental biomechanical study.

SAMPLE POPULATION

Acetal homopolymer (Delrin) rods stabilized with locking plates and screws (Arthrex OrthoLine).

METHODS

One of four stabilization techniques (UP, OP2.0, OP2.4, OP3.0) was applied to rods with a fixed fracture gap. Constructs were fatigue tested under axial compression (90,000 cycles; 4-196 N) followed by static load to failure. Cyclic displacement was evaluated after the first, middle, and last 100 cycles. Stiffness and strength were analyzed during static axial compression load to failure.

RESULTS

During cyclic testing, UP experienced 3.5, 3.8, and 4.1 times the gap strain of OP2.0, OP2.4, and OP3.0, respectively (p < 0.0075). Fatigue and construct design had significant effects on displacement (p < .0001). OP2.0, OP2.4, and OP3.0 demonstrated 2.5, 3.0, and 4.1 times the strength and 3.0, 3.6, and 4.2 times the stiffness of UP, respectively (p < .0002).

CONCLUSION

In the present in vitro fracture gap model, OP constructs were stronger and stiffer than UP under dynamic and static axial compression, and OP stiffness increased with increasing implant size.

CLINICAL SIGNIFICANCE

The results of this study demonstrate objective biomechanical advantages of OP compared to UP. Based on these results, orthogonal plating can be considered when increased fixation strength and stiffness are warranted.

Effect of an Orthogonal Locking Plate and Primary Plate Working Length on Construct Stiffness and Plate Strain in an In vitro Fracture-Gap Model

OBJECTIVE

 The aim of this study was to compare stiffness and strain of an in vitro fracture-gap model secured with a primary 3.5-mm locking compression plate (LCP) at three primary plate working lengths without and with an orthogonal 2.7-mm LCP.

STUDY DESIGN

 Primary plate screw configurations modeled short working length (SWL), medium working length (MWL), and long working length (LWL) constructs. Construct stiffness with and without an orthogonal plate during nondestructive four-point bending and torsion, and plate surface strain measured during bending, was analyzed.

RESULTS

 Single plate construct stiffness was significantly, incrementally, lower in four-point bending and torsion as working length was extended. Addition of an orthogonal plate resulted in significantly higher bending stiffness for SWL, MWL, and LWL (p < 0.05) and torsional stiffness for MWL and LWL (p < 0.05). Single plate construct strain was significantly, incrementally, higher as working length was extended. Addition of an orthogonal plate significantly lowered strain for SWL, MWL, and LWL constructs (p < 0.01).

CONCLUSION

 Orthogonal plate application resulted in higher bending and torsional construct stiffness and lower strain over the primary plate in bending in this in vitro model. Working length had an inverse relationship with construct stiffness in bending and torsion and a direct relationship with strain. The inverse effect of working length on construct stiffness was completely mitigated by the application of an orthogonal plate in bending and modified in torsion.

Surgical stabilization of a distal tibial fracture in a jungle cat (Felis chaus) using orthogonal double plating

The jungle cat (Felis chaus) is a member of the genus Felis within the family Felidae, native to south-east Asia, west Asia and north Africa. A 2-year-old male jungle cat was referred with a history of lameness of 3 days duration. At the time of presentation, the animal had non-weight-bearing lameness of the right hindlimb. Examination identified crepitation and instability in the distal diaphyseal region of the right tibial bone. Radiographs confirmed the presence of fractures in the distal diaphyseal region of the right tibia and fibula. Double plating of the tibia was employed for used fixation. The animal was evaluated 2, 4 and 8 weeks post-operatively, and the procedure was considered to have been successful with no observed surgical complications.

Vesicoureteral reflux by contrast ultrasound, comparison with voiding and retrograde urethrocystography: A prospective accuracy study

INTRODUCTION

Diagnosis of vesicoureteral reflux (VUR) plays an important role in the management and follow-up of children presenting with urinary tract infection. This study compared voiding uronosography (VUS) as a diagnostic method for the diagnosis of VUR with the "gold standard", voiding or micturating cystourethrography (MCU). The objective of the study is not only to compare the effectiveness of both methods, but also to assess the feasibility of implementing VUS technically and economically in a large tertiary radiology center in South America.

MATERIALS AND METHOD

This was a prospective accuracy study that include 41 patients (a total of 85 ureteral units) aged between 1 month and 16 years. VUS was performed in an alternative form as regular MCU, by injecting microbubble contrast solution (SonoVue©) into the bladder through an intermittent catheter and evaluating the presence of reflux with ultrasound. MCU was always performed immediately after VUS. One pediatric radiologist evaluated all VUS exams, while a second independent pediatric radiologist evaluated all MCU exams, with both blinded to each other's assessments.

RESULTS

Comparing VUS with MCU in the diagnosis of VUR, we observed a sensitivity of 92.3 % (95 % CI 74.9-99.1 %), specificity of 98.3 % (95 % CI 90.9-100 %), positive predictive value of 96.0 % (95 % CI 79.6-99.9 %), negative predictive value of 96.7 % (95 % CI 88.5-99.6 %) and a Kappa of 0.916 (0.822-1.000). When comparing the VUR grading between VUS and MCU the agreement between the two methods was high with a Kendall's Tau-b > 0.9. VUS failed to diagnose two grade 1 VUR reflux cases in teenagers while diagnosing one grade 4 VUR in a very dilated kidney-ureter unit, which was missed on MCU. VUS and MCU had similar costs when considering the price of the ultrasound contrast agent.

DISCUSSION

VUS is a reliable alternative method to MCU for the diagnosis of VUR with the advantages of not exposing the child to ionizing radiation and potentially being more accessible due to the greater availability of ultrasound equipment. Limitations to this study include the usage of a single ultrasound equipment, which limits its generalizability and not evaluating the interobserver variability.

CONCLUSION

Consideration should be given to implementing VUS for the diagnosis of VUR, particularly in centers without fluoroscopy equipment available, since the exam's performance and cost are comparable to those of the MCU.

Management of insufficiency fractures associated with long-term bisphosphonate therapy in a cat

Case summary

A 10-year-old spayed female domestic medium hair cat presented after sustaining atraumatic insufficiency fractures of the right calcaneus and the left tibia approximately 6 weeks apart. Chronic alendronate therapy had been ongoing for 9 years for the management of previously diagnosed idiopathic hypercalcemia. The right calcaneal fracture was managed non-operatively due to minimal functional impairment. The left tibial fracture was managed via open reduction and internal fixation with orthogonal plating. Alendronate therapy was discontinued at the time of the fracture repair with prednisolone being used to manage the hypercalcemia. Despite rapid clinical improvement, the tibial fracture had a protracted healing course, with clinical union only being achieved 22 weeks postoperatively. At 17 months postoperatively, the idiopathic hypercalcemia remained well controlled. Gait assessment, orthopedic examination and orthogonal radiographs performed at this time revealed resolution of left pelvic limb lameness, a normal orthopedic examination of the left pelvic limb and no evidence of implant-associated complications. Monitoring is ongoing but at the time of publication, no further fractures have occurred.

Relevance and novel information

As reported in humans, this case report gathers evidence of associations between bisphosphonate treatment and the occurrence of insufficiency fractures in cats, and provides evidence that stress reactions may precede their development. If bisphosphonate therapy is utilized in the long term, serial radiographic monitoring for signs of impending fracture may be warranted. Fracture repair can be successful in cats that have received long-term bisphosphonate therapy, but delayed healing should be anticipated and implant choices made accordingly.

Correlation of Bone Strength in an Animal Model (Rabbit) After Fracture and During the Period of Fixation with a Titanium Micro Plate

The period of bone healing after trauma goes through certain physiological processes. In situations where a bone fracture occurs, our intention is to surgically position in an appropriate morpho-anatomical position. For osteosynthesis we used vipla wire and micro plates with corresponding screws.

The aim of our research was to evaluate the optimal time for the removal of the osteosynthetic material, fracture site biomechanical stability, and measurement of the callus thickness.

For this research ten 4 months old rabbits with right leg femur fracture were used. Osteosynthesis was done with titanium micro plates, corresponding screws and vipla wire. Experimental animals were observed through the post-operative period at the first and seventh postoperative day and there on at 2, 4, 6, 9, 12 weeks. Further additional fixation was needed in one of the rabbits in the second week.

The postoperative period provided us information about the optimal moment for the removal of titanium micro plates. It showed that over a period of six weeks, the bone had almost all normal biomechanical properties. Significantly greater strength and rigidity of the recovered femur were obtained after 12 weeks. Micro plates that were removed after 4, 6 or 9 weeks, did not need furhter fixation and therefore fixation was not applied, compared to those placed during the 12 weeks. X Ray evaluation provided us with follow up results of fracture healing.

The results suggest that it is acceptable to remove titanium micro plates after a period of healing, that is, after the formation of the callus and bridging of the fracture gap and diastasis with newly formed bone.

Biomechanical comparison of a modified TPLO plate, a locking compression plate, and plate-rod constructs applied medially in a proximal gap model in canine synthetic tibias

ABSTRACT The aim of this study was to develop a modified tibial plateau leveling osteotomy (TPLO) plate and to compare its biomechanical properties with a locking compression plate (LCP) and plate-rod constructs for the stabilization of experimentally induced gap fractures in canine synthetic tibias. The tibial models were assigned to either repair with a modified TPLO plate (Group 1), locking compression plate construct (Group 2), or plate-rod construct (Group 3). The specimens were loaded to failure in axial compression, three-point mediolateral and craniocaudal bending. There was no statistical difference between the three groups regarding stiffness (N/mm) and deformation (mm) in axial compression. The modified TPLO plate achieved load to failure similar to the plate-rod construct in craniocaudal bending. There was no significant difference between groups on mediolateral bending tests regarding load to failure and deformation. Furthermore, there was no significant difference in stiffness between groups 1 and 2. In conclusion, the modified TPLO plate had similar mechanical properties to LCP and plate-rod construct in the axial compression and bending tests. Nonetheless, clinical studies with a large population of dogs are required to determine the value of this new implant in proximal tibial fracture repair.

Feline Diaphyseal Fractures: Management and treatment options

PRACTICAL RELEVANCE

Cats frequently present with diaphyseal fractures, which require treatment in order to achieve a good return to function. These fractures often occur due to significant trauma; for example, as a result of road traffic accidents, high-rise syndrome and dog bite wounds. The first priority is to ensure the patient is systemically well before embarking on any specific surgical treatment of a fracture.

CLINICAL CHALLENGES

Surgical management of diaphyseal fractures can be challenging due to the surgical approach for some bones being technically demanding, for example because of the presence of important neurovascular structures, and the small size of feline bones, which limits the choice of implant size and strength. Further, it may be difficult to visualise fracture alignment when using minimally invasive techniques, although the use of intraoperative fluoroscopy can aid with this, and malalignment can be common for some fracture repairs, particularly in cases where anatomical reconstruction is not possible.

AIMS

This review focuses on diaphyseal long bone fractures and aims to assist decision-making, with an overview of the management and treatment options available.

EVIDENCE BASE

Many textbooks and original articles have been published on aspects of managing fractures in small animals. The authors also provide recommendations based upon their own clinical experience.

Clinical outcomes of orthogonal plating to treat radial and ulnar fractures in toy-breed dogs

OBJECTIVES

To describe the results of orthogonal plating (OP) as a treatment for fractures of the radius and ulna in toy-breed dogs.

MATERIALS AND METHODS

The medical records (June 2011 to April 2019) of toy-breeds in which the OP technique using non-locking cuttable plates was employed to treat radial and ulnar fractures were reviewed. The inclusion criteria included a bodyweight of 3.5 kg or less, fracture of the diaphysis of the radius and ulna of one or both forelimbs, and the availability of follow-up radiographs. Revision surgeries were also included.

RESULTS

Fifteen limbs that underwent initial fracture repair and five that underwent revision surgery met the inclusion criteria. The radial and ulnar fractures healed in 19 limbs at the final follow-up. Synostosis of the radius and ulna at the fracture sites was observed in one limb. Re-fracture after cranial plate removal was observed in one case. All dogs exhibited successful return of normal limb function at the final clinical and radiographic follow-up (mean, 104.7 ± 67.1 days; median, 79.5 days; range: 35 to 248 days). Long-term follow-up data obtained via telephone interviews to owners or referring veterinarians were available for 15 cases and confirmed maintenance of normal limb function in all dogs (mean, 32.5 ± 17.6 months; median, 26 months; range: 11 to 69 months).

CLINICAL SIGNIFICANCE

OP allowed the successful open reduction of radial and ulnar fractures, facilitating bone union in both the radius and ulna and a return to normal limb function in a series of toy-breed dogs.

DOUBLE PLATING FOR FRACTURES IN GIANT ANTEATERS (MYRMECOPHAGA TRIDACTYLA)

The fixation of fractures in wild animals has been a great challenge for veterinarians, because they will inevitably face a unique anatomical characteristic with scarce studies or reports published. Fracture fixation should promote adequate stability and early return to limb function, taking into account biomechanical characteristics of the bones, body weight, and natural habits of wildlife. Three bone fractures from two giant anteaters (Myrmecophaga tridactyla) referred at the veterinary teaching hospital on different occasions were treated by a double plating technique. The two free-ranging anteaters incurred their injuries when struck by an automobile. The first anteater (Ant 1) had a complete oblique fracture of the proximal third of the right femur and a complete comminuted fracture of the distal third of the right tibia. Surgical stabilization was performed by double plating to stabilize the femur and tibia. The second anteater (Ant 2) had a complete transverse fracture of the mid-diaphysis of the right radius and ulna, and it was fixed with a medial plate on the radius and a caudal plate on the ulna. The patients were able to walk 24 hr after the surgical procedures. Bone consolidation was observed at 60 days postoperatively, with no complications. The biggest challenges were related to anatomical characteristics for surgical approaches and the ability to promote a fixation strong enough to support the weight and strength of the animal, allowing early return to limb function.

Clinical application of the small I-Loc interlocking nail in 30 feline fractures: A prospective study

OBJECTIVE

To describe medium-term functional outcome after nail osteosynthesis in feline traumatology and report clinically relevant recommendations for I-Loc angle-stable interlocking nail use in cats.

STUDY DESIGN

Prospective clinical study.

SAMPLE POPULATION

Client-owned cats (n = 29).

METHODS

Consecutive cases with femoral, tibial, or humeral fractures were included. Outcome measures included fracture and surgical procedure description, limb alignment, nail size vs body weight (BW), percentage of nail medullary canal (MC) fill, time to limb function at clinical union (CU), and complications. Descriptive statistics were reported and compared with historical data.

RESULTS

Bone distribution was 53.3% femora, 30% tibiae, and 16.7% humeri. There were six epimetaphyseal and 24 diaphyseal fractures. Overall, 67% of fractures were comminuted. Open reduction and minimally invasive techniques were used in 73% and 27% of cases, respectively. Seventeen I-Loc 3 (cat mean BW 4.4 ± 2.2 kg) and 13 I-Loc 4 (cat mean BW 5.2 ± 1.2 kg) nails were placed with mean MC fill of ≤50%. Average time to CU was 7.2 weeks. At CU, lameness had resolved or was mild in every cat, and all cats ultimately regained full limb function. No major complications were encountered.

CONCLUSION

Because of improved CU times, excellent functional outcomes, and low complication rate, our results provide evidence that I-Loc nails are safe and effective for feline traumatology.

CLINICAL SIGNIFICANCE

The I-Loc may be advantageous for fixation of epimetaphyseal fractures. Because of feline bone specific dimensional constraints, I-Loc 3 is likely appropriate for all feline humeri and most tibiae, while I-Loc 4 is well sized for feline femora.

How Do the Locking Screws Lock? A Micro-CT Study of 3.5-mm Locking Screw Mechanism

OBJECTIVE

 To quantify the amount of the screw head thread and the plate hole thread connection in two 3.5 mm locking plates: Locking Compression Plate (LCP) and Polyaxial Locking System (PLS).

MATERIALS AND METHODS

 A micro - CT scan of a screw head - plate hole connection was performed pre- and post destructive tests. Tests were performed on bone surrogates in a fracture gap model. The 3.5 LCP and 3.5 PLS plates, with 3 perpendicular screws per segment were used in a destructive static test. The 3.5 PLS plates with mono- and polyaxial screws were compared in a cyclic fatigue tests in two orthogonal directions. Pre - and post - test scan datasets were compared. Each dataset was converted into serial images depicting sections cut orthogonally to locking screw axis. The amount of engagement was detected through automated image postprocessing.

RESULTS

 The mean amount of the thread connection for the LCP was 28.85% before and 18.55% after destructive static test. The mean amount of the connection for the PLS was 16.20% before and 14.55% after destructive static test. When inserted monoaxially, the mean amount of the connection for the PLS screws was 14.4% before and 19.24% after destructive cyclic test. The mean amount of the connection for the polyaxial inserted PLS screws when loaded against plate thickness was 2.99% before and 2.08% after destructive cyclic test. The mean amount of the connection for the polyaxial inserted PLS screws when loaded against plate width was 3.36% before and 3.93% after destructive cyclic test. The 3D visualization of the thread connection showed that the initial interface points between screw head and plate hole are different for both LCP and PLS after the destructive testing. Depending on the type of applied force, there was either loss or increase of the contact.

CLINICAL RELEVANCE

 Micro-CT offers news possibilities in locking implant investigation. It might be helpful in better understanding the nature of locking mechanism and prediction of possible mode of failure in different systems.

Perceptions of minimally invasive osteosynthesis: A 2018 survey of orthopedic surgeons

OBJECTIVE

To report perspectives of minimally invasive osteosynthesis (MIO) techniques in veterinary surgical practice in 2018.

STUDY DESIGN

Electronic questionnaires.

SAMPLE POPULATION

Diplomates and residents of the American College of Veterinary Surgery and European College of Veterinary Surgery and members of the Veterinary Orthopedic Society.

METHODS

Survey questions pertaining to MIO and minimally invasive plate osteosynthesis (MIPO) were sent electronically to the sample population. Questions assessed training, current caseload, benefits, and limitations of MIO and MIPO.

RESULTS

Two hundred fifty-six veterinary surgeons completed questions pertaining to MIO, and 238 veterinary surgeons completed questions pertaining to MIPO. With regard to MIO, only 16% of respondents reported that they performed MIO regularly or exclusively, and 62% wanted to perform more MIO than they were currently undertaking. Tibial fractures were most commonly selected for MIO/MIPO stabilization techniques in both cats and dogs. Challenges in achieving adequate fracture reduction were identified as the greatest limitations of MIO/MIPO techniques. Forty-three percent of respondents felt there were not enough MIPO training opportunities.

CONCLUSION

Currently, MIO/MIPO techniques are performed infrequently, with a large proportion of respondents revealing that they would like to perform more in the future. There is also evidence that additional training opportunities would be welcomed for MIPO.

CLINICAL SIGNIFICANCE

The results of our survey provide evidence that, despite the benefits of MIO and MIPO compared with more traditional fracture stabilization approaches, significant barriers must be overcome before the techniques are likely to be more widely adopted.