An assessment of the fixin tplo jig to generate effective compression using a transverse fracture model

The objective of this study was to determine compressive loads that could be generated using a tibial plateau leveling osteotomy (TPLO) jig with a tensioned strand of 18-gauge stainless steel orthopedic wire in a simulated transverse fracture model. The wire was sequentially tensioned using heavy needle holders or an AO wire tightener. Recorded loads were subsequently compared to loads generated by applying a 3.5 mm limited contact-dynamic compression plate (LC-DCP) as a compression plate. Two segments of 2 cm diameter Delrin rod were placed in a testing apparatus and used to simulate a transverse fracture. A load cell was interposed between the two segments to measure the compressive loads generated during the application of the TPLO jig or the LC-DCP. Compression was generated by sequential tensioning a strand of 18-gauge wire secured through the base of the arms of the TPLO jig or by placing one or two load screws in the LC-DCP. Wires were tensioned using heavy needle holders or an AO wire tightener. Eight replicates of each construct were tested. Recorded loads were compared using a one-way repeated measures ANOVA and Tukey Honestly Significant Difference test. The wire being tensioned broke while attempting a second quarter rotation of the needle holders and when the crank handle of the AO wire tightener was advanced beyond two rotations. The mean + SD peak compressive loads recorded when tensioning the wire using the heavy needle holders and AO wire tightener was 148 ± 7 N and 217 ± 16 N, respectfully. The mean ± SD load recorded after placement of the first and second load screw in the LC-DCP was 131 ± 39 N and 296 ± 49 N, respectively. The compression generated by placing two load screws in the LC-DCP was superior to the compression generated using the jig. The maximum load recorded by tensioning the wire secured through the TPLO jig using the AO wire tightener was superior to the compression generated by placing a single load screw and tensioning the wire using needle holders. Our results demonstrate that the TPLO jig allows surgeons to compress transverse fractures or osteotomies effectively. Tensioning the AO wire tightener allows for sequential tensioning and generates superior compressive loads than tensioning wires with heavy needle holders.

Locking conical coupling plates in small animal orthopedics: A review

Conical coupling locking plates (CCP) have become an interesting alternative in veterinary orthopedics and traumatology. Available data in this regard, however, must be interpreted with caution, and several studies are still required to reach definitive conclusions on the clinical use of these implants. In this context, this review aims to discuss CCP applications and mechanical aspects in small animals and summarize in vivo, in vitro and ex vivo study results.

Use of a Transarticular Calcaneo-Tibial Locking Plate for Temporary Immobilization of the Tarsocrural Joint following Surgical Repair of Common Calcaneal Tendon Rupture in Eight Dogs

OBJECTIVE

 The purpose of this clinical communication is to report the management of common calcaneal tendon rupture in dogs using a transarticular calcaneo-tibial locking plate as a method of temporary immobilization of the tarsocrural joint to support primary repair of the common calcaneal tendon.

STUDY DESIGN

 Dogs presented with partial or complete common calcaneal tendon rupture treated with primary tendon repair supported by the transarticular calcaneo-tibial locking plate technique from July 2016 to December 2019 were included. The tarsus was placed at a standing angle of 150 degrees and the pre-contoured Fixin locking 'L' or 'T' plate was medially applied with two locking screws inserted in the calcaneus and two screws inserted in the distal tibia. Tendon healing judgement was mostly based on clinical palpation and ultrasound examination was not performed in all the cases. Plates were removed in all dogs 6 weeks postoperatively.

RESULTS

 All tendons healed and no complications at the level of the tenorrhaphy were noted in the postoperative period. All dogs returned to hunting activity with full function of the affected limb. No major complications requiring revision surgery were observed. Minor complications occurred in two cases; osteomyelitis and screw pull-out.

CONCLUSION

 The use of a transarticular calcaneo-tibial locking plate for temporary immobilization of the tarsocrural joint after surgical repair of common calcaneal tendon rupture appears to be an effective technique with comparable results to other reported techniques.

Radiographically confirmed outcomes after fracture repair with a PLS polyaxial locking system in 40 dogs and cats

OBJECTIVE

To report radiographic findings and complications after fracture repair with a new polyaxial locking plate system (PLS polyaxial locking system; Aesculap/B Braun, Tuttlingen, Germany) in dogs and cats.

STUDY DESIGN

Retrospective case review from four veterinary practices.

SAMPLE POPULATION

Twenty-six dogs and 14 cats (40 long bone fractures).

METHODS

Medical and radiographic records of dogs and cats with long bone fractures treated with the PLS were reviewed. Cases were included when operative records were complete and included documentation of radiographic union or complications. Phone interviews of owners were performed for long-term follow-up. Ancillary methods of fracture fixation and associated complications were recorded.

RESULTS

Only two complications were recorded, one of which required a revision surgery. Radiographic follow-up was performed for all fractures. Radiographic union without complications was achieved in 38 of 40 (95%) fractures. Radiographic union was documented before 60 days in 19 of 40 (47.5%) fractures, between 61 and 90 days in 15 of 40 (37.5%) fractures, and after 90 days in six of 40 (15%) fractures. A functional union was observed at a mean time ± SD of 70.8 ± 38.9 days (range, 32-182). One or more ancillary fixation methods were used in 27 of 40 (67.5%) fractures.

CONCLUSION

The PLS polyaxial locking system was often used with adjunct fixation in this series, and radiographically confirmed healing without complications was documented in most cases.

CLINICAL SIGNIFICANCE

Use of the PLS can result in high success rates for fracture repair in dogs and cats, but ancillary fixation should be strongly considered.

Fracture Repair in Cats Using a Conical Coupling Mini 1.9 to 2.5 mm Locking Plate System

OBJECTIVE

 The aim of this study was to retrospectively evaluate the clinical application of the Fixin mini 1.9 to 2.5 system for the treatment of long bone fractures in cats. We proposed that the Fixin mini system would successfully stabilize long bone fractures in cats with a healing time and complication rate similar to those previously reported for feline fractures using other locking bone plate systems.

MATERIALS AND METHODS

 Medical records and radiographs of cats with long bone fractures stabilized with the Fixin mini 1.9 to 2.5 system were retrospectively reviewed. Signalment, body weight, bone(s) fractured, region of bone fractured, fracture classification, concurrent orthopaedic injuries, complications, time to functional union, if minimally invasive plate osteosynthesis techniques were used, plate size, number of plates, bone graft use and ancillary methods of fixation were recorded.

RESULTS

 Fifty-six fractures in 54 cats were included. Mean time to radiographic union was 8.8 weeks. Complications were recorded in 8 out of 56 fractures. Major complications occurred in 4 of 56 fractures and minor complications occurred in 4 of 56 fractures.

CONCLUSION

 The Fixin mini 1.9 to 2.5 system had an overall complication rate and time to functional union similar to that of other implant systems used to treat feline long bone fractures and it appears suitable for repair of a wide variety of long bone fracture configurations in cats.

Biomechanical Comparison of Two Conical Coupling Plate Constructs for Cat Tibial Fracture Stabilization

OBJECTIVE

 This study aimed to compare the biomechanical characteristics of two conical coupling plate (CCP) constructs in an ex vivo feline tibial fracture gap model.

STUDY DESIGN

 Paired tibiae harvested from eight recently euthanatized cats were alternately assigned to one of two stabilization groups. One tibia was stabilized with a standard, 6-hole, 2.5-mm CCP and the contralateral tibia was stabilized with a 6-hole, 2.5-mm prototype CCP (pCCP). Non-destructive cyclic four-point craniocaudal bending, mediolateral bending and axial compression testing were performed, and stiffness was recorded. The specimens were then loaded to failure in axial compression, and yield and failure loads were recorded.

RESULTS

 During non-destructive testing, the pCCP constructs were significantly stiffer than the CCP constructs in both modes of bending and axial loading. Both constructs demonstrated significantly greater craniocaudal bending stiffness compared with mediolateral bending. Yield load and failure load were significantly greater for the pCCP constructs.

CONCLUSION

 The augmented design of the pCCP yielded superior mechanical characteristics during both non-destructive and destructive testings compared with constructs employing standard CCP. The more rigid design of the pCCP suggests that this implant may be better at withstanding greater loads, particularly when applied in a bridging fashion, during the postoperative convalescence. Further investigations are warranted to prospectively evaluate the clinical performance of the pCCP.

Stifle arthrodesis using a locking plate system in six dogs

Objectives: To describe the use of the Fixin locking plate system for stifle arthrodesis in dogs and to retrospectively report the clinical and radiographic outcomes in six cases.[uni2028]

Materials and methods: Medical records of dogs that had arthrodesis with the Fixin locking plate system were reviewed. For each patient, data pertaining to signalment and implant used were recorded. Plate series and thickness, number of screws placed, number of cortices engaged, and screw diameters were also recorded. The outcome was determined from clinical and radiographic followups. Radiographic outcomes assessed included the measurement of the postoperative femoral-tibial angle in the sagittal plane.

Results: Six dogs met the inclusion criteria for the study. Mean body weight was 13 kg (range: 3 - 34 kg). Radiographic follow-up (mean: 32 weeks, range: 3 - 52 weeks) was available for all dogs. In one case, an intra-operative complication occurred. In another case, a tibial fracture occurred 20 days after surgery. All arthrodeses healed and no implant complication was detected although all cases had mechanical lameness.

Clinical significance: Stifle arthrodesis can be performed successfully using a Fixin locking plate system.

Complications of appendicular fracture repair in cats and small dogs using locking compression plates

Objective: Our objectives were: 1) to review the complications associated with stabilization of appendicular fractures in cats and small dogs using locking compression plates (LCP), and 2) to identify factors that could influence fixation construct stability.

Study design: Retrospective clinical study.

Materials and methods: Medical and radiographic records of cats and small dogs with appendicular fractures treated with LCP were reviewed. Only cases with adequate follow-up to document clinical union and cases for which complications appeared before the clinical union were included. Complications were classified as implant-related complications or other complications. Cases with implant-related complications were compared to cases with non-implant-related complications for differences in signalment (species, age, body weight, multiple fractures), fracture location and type (fractured bone, fracture localization, closed or open fracture), reduction method (open reduction and internal fixation [ORIF] or minimally invasive plate osteosynthesis [MIPO]) and fixation evaluations (implant size, platebridging ratio, plate span ratio, working length, plate screw density, number of screws and cortices engaged per plate and per main fragment, ratio between screw and bone diameter at the narrowest aspect of the bone, and presence of ancillary fixation).

Results: Seventy-five fractures from 63 cats (64 fractures) and 10 dogs (11 fractures) met the inclusion criteria. Eight humeral, 13 radio-ulnar, 26 femoral, and 28 tibio-fibular fractures were treated. Primary repair of the fracture was performed using 2.0 mm and 2.4 mm LCP in 22 and 53 fractures, respectively. Overall and implant-related complications were encountered in 13 and seven of 75 fractures, respectively. Fixation failure was not significantly associated with any aforementioned factor considered in this study, and in particular, there was no significant difference in the occurrence of fixation failure between fractures stabilized with two, or more than two, bicortical locking screws per main fragment.

Clinical significance: 2.0 mm and 2.4 mm LCP were used to manage appendicular fractures in cats and small dogs. The overall complication and fixation failure rate were comparable to those reported in previous studies in which various locking plate systems were used.

Online Supplementary Material for this article is available at: http://dx.doi.org/10.3415/VCOT-14-09-0146

Clinical evaluation of a mini locking plate system for fracture repair of the radius and ulna in miniature breed dogs

Objectives: To retrospectively evaluate the effectiveness of a novel 1.2 mm mini locking plate system in treating fractures of the radius and ulna in miniature breed dogs.

Methods: Medical records and radiographs of miniature breed dogs with fractures treated with a 1.2 mm mini locking plate system were reviewed. The inclusion criteria were: body weight of 2.5 kg or less, trans-verse or short oblique fracture of the radius and ulna, and treatment with a mini locking plate system as the sole method of fixation. For each patient, data including signalment, time to radiographic union, use of bone graft or other agents, and previous repair attempts were recorded. The outcome and complications were determined from clinical and radiographic follow-up examinations.

Results: Fourteen cases with a mean radial width of 4.5 mm (± 0.8 mm) were included into this study. The fractures healed without failure of fixation in all cases. Mean time to adequate radiographic union was 8.4 weeks (± 2.6 weeks). Major complications were not seen in any of the cases, and minor complications occurred in three of the cases. Limb function was graded as ‘normal’ in 10 cases and ‘occasional lameness’ in four cases.

Clinical significance: The mini locking system evaluated in this study was an effective treatment method for radial and ulnar fractures in miniature breed dogs with a radial width smaller than 5.5 mm.

Supplementary Material to this article is available online at http://dx.doi.org/10.3415/VCOT-16-01-0014.

Biomechanical comparison of a 3.5-mm conical coupling plating system and a 3.5-mm locking compression plate applied as plate-rod constructs to an experimentally created fracture gap in femurs of canine cadavers

OBJECTIVE To compare stiffness and resistance to cyclic fatigue of two 3.5-mm locking system plate-rod constructs applied to an experimentally created fracture gap in femurs of canine cadavers. SAMPLE 20 femurs from cadavers of 10 mixed-breed adult dogs. PROCEDURES 1 femur from each cadaver was stabilized with a conical coupling plating system-rod construct, and the contralateral femur was stabilized with a locking compression plate (LCP)-rod construct. An intramedullary Steinmann pin was inserted in each femur. A 40-mm gap then was created; the gap was centered beneath the central portion of each plate. Cyclic axial loading with increasing loads was performed. Specimens that did not fail during cyclic loading were subjected to an acute load to failure. RESULTS During cyclic loading, significantly more LCP constructs failed (6/10), compared with the number of conical coupling plating system constructs that failed (1/10). Mode of failure of the constructs included fracture of the medial or caudal aspect of the cortex of the proximal segment with bending of the plate and pin, bending of the plate and pin without fracture, and screw pullout. Mean stiffness, yield load, and load to failure were not significantly different between the 2 methods of stabilization. CONCLUSIONS AND CLINICAL RELEVANCE Both constructs had similar biomechanical properties, but the conical coupling plating system was less likely to fail than was the LCP system when subjected to cyclic loading. These results should be interpreted with caution because testing was limited to a single loading mode.

Stabilisation of periarticular fractures and osteotomies with a notched head locking T-plate

OBJECTIVE

To report the clinical outcomes and complications of small animals that had articular or periarticular fractures or osteotomies stabilised with a notched head locking T-plate.

METHODS

Medical records were searched retrospectively to identify animals that had a notched head locking T-plate used to stabilise a small articular or periarticular bone fragment.

RESULTS

Nine dogs and two cats had an articular or periarticular bone fragment stabilised with a 2.0- or 2.4-mm notched head locking T-plate (12 procedures). The median body weight was 4.7 kg. The plate was modified by removing holes in 10/12 procedures and a combination of locking and non-locking screws were used in 7/12 procedures. All fractures or osteotomies progressed to clinical union. There were two intraoperative complications (intra-articular screw placement and overlong screw) and two postoperative complications (skin necrosis and stress protection)

CONCLUSIONS

This study reports the successful use of a 2.0- or 2.4-mm notched head locking T-plate for articular or periarticular fractures or osteotomies in a variety of small-breed dogs and cats. Care must be taken to prevent inadvertent penetration of the articular surface, particularly in regions such as the proximal tibia. The ability to modify the plate dimensions intraoperatively proved beneficial in most cases.

Biomechanical comparison of two locking plate constructs under cyclic torsional loading in a fracture gap model. Two screws versus three screws per fragment

OBJECTIVES

The number of locking screws required per fragment during bridging osteosynthesis in the dog has not been determined. The purpose of this study was to assess the survival of two constructs, with either two or three screws per fragment, under cyclic torsion.

METHODS

Ten-hole 3.5 mm stainless steel locking compression plates (LCP) were fixed 1 mm away from bone surrogates with a fracture gap of 47 mm using two bicortical locking screws (10 constructs) or three bicortical locking screws (10 constructs) per fragment, placed at the extremities of each LCP. Constructs were tested in cyclic torsion (range: 0 to +0.218 rad) until failure.

RESULTS

The 3-screws constructs (29.65 ± 1.89 N.m/rad) were stiffer than the 2-screws constructs (23.73 ± 0.87 N.m/rad), and therefore, were subjected to a greater torque during cycling (6.05 ± 1.33 N.m and 4.88 ± 1.14 N.m respectively). The 3-screws constructs sustained a significantly greater number of cycles (20,700 ± 5,735 cycles) than the 2-screws constructs (15,600 ± 5,272 cycles). In most constructs, failure was due to screw damage at the junction of the shaft and head. The remaining constructs failed because of screw head unlocking, sometimes due to incomplete seating of the screw head prior to testing.

CLINICAL SIGNIFICANCE

Omitting the third innermost locking screw during bridging osteosynthesis led to a reduction in fatigue life of 25% and construct stiffness by 20%. Fracture of the screws is believed to occur sequentially, starting with the innermost screw that initially shields the other screws.

Rapid prototyping to design a customized locking plate for pancarpal arthrodesis in a giant breed dog

This report describes the treatment of traumatic carpal hyperextension in a giant breed dog by pancarpal arthrodesis using a custom-made Fixin locking plate, created with the aid of a three-dimensional plastic model of the bones of the antebrachium produced by rapid prototyping technology. A three-year-old 104 kg male Mastiff dog was admitted for treatment of carpal hyperextension injury. After diagnosis of carpal instability, surgery was recommended. Computed tomography images were used to create a life-size three-dimensional plastic model of the forelimb. The model was used as the basis for constructing a customized 12-hole Fixin locking plate. The plate was used to attain successful pancarpal arthrodesis in the animal. Radiographic examination after 74 and 140 days revealed signs of osseous union of the arthrodesis. Further clinical and radiographic follow-up examination three years later did not reveal any changes in implant position or complications.