The effect of grip location on Kirschner wire bend characteristics: An in vitro study.

OBJECTIVE: To determine the effect of Kirschner wire (K-wire) grip location on bend angle, bend radius, and torque when performing a Z-bend technique. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Ten samples at each of five grip locations for each of three K-wire diameters. METHODS: K-wires of three diameters (0.9, 1.1, 1.6 mm) were drilled into PVC pipe, and a Jacob's chuck was used to bend the wires at five periodic grip locations (distance from the bone model). Torque, bend angle, and bend radius were determined for each sample. Outcome variables were statistically analyzed by grip location to determine significant relationships. RESULTS: A grip location of 2.0 cm in the 0.9 mm K-wire group minimized bend angle (mean ± SD: 75.92° ± 0.81) and bend radius (2.89 mm ± 0.08). A grip location of 3.0 cm in the 1.1 mm K-wire group minimized bend angle (72.88° ± 0.98) and bend radius (2.47 mm ± 0.20). A grip location of 3.0 cm minimized bend angle (74.38° ± 1.93) and bend radius (2.71 mm ± 0.27) in the 1.6 mm K-wire group. Torque at these grip locations for the 0.9, 1.1, and 1.6 mm K-wires was 6.50 N-m ± 0.0, 11.00 N-m ± 0.0, and 19.05 N-m ± 0.16, respectively. CONCLUSION: Bend angle and bend radius can be minimized by bending K-wires at specific grip locations, though torque is not minimized at these locations. Clinical significance These findings provide an evidence-based recommendation of where surgeons should grip K-wires when bending them.

Biomechanical comparison of canine median sternotomy closure using suture tape and orthopedic wire cerclage.

OBJECTIVE: To compare the mechanical properties of suture tape and orthopedic wire cerclage in an ex vivo canine median sternotomy model. STUDY DESIGN: Ex vivo. ANIMALS: Twelve large-breed canine cadaveric sternums. METHODS: Median sternotomies were performed, leaving the manubrium intact. The specimens were randomly assigned to group W (20-gauge stainless steel orthopedic wire cerclage in a figure-of-eight pattern) or group ST (suture tape in a figure-of-eight pattern). Each specimen was laterally distracted until failure using an electrodynamic materials-testing system. RESULTS: No differences were observed for displacement, yield load, maximum load, implant failure between the groups. The orthopedic wire construct was stiffer than the suture tape construct. CONCLUSION: Suture tape was biomechanically similar to orthopedic wire cerclage for sternotomy closure in dogs, although wire constructs were stiffer. CLINICAL SIGNIFICANCE: Suture tape may represent an alternative to cerclage wire for sternotomy closure in dogs. Additional studies evaluating its clinical use are needed.

Double-loop cerclage resists greater loads for more cycles than twist and single-loop cerclage.

OBJECTIVE: To compare the mechanical performance of cerclage secured with twist, single-loop, and double-loop knots subjected to cyclic loading. STUDY DESIGN: In vitro biomechanical study. SAMPLE POPULATION: Twist, single-loop and double-loop cerclage configurations of 1.0 mm wire. METHODS: The peak load resisted by each cerclage type was determined (n = 6). Cerclage were loaded cyclically to 80%, 60%, 40%, or 20% of its peak load (n = 8 per load level). The number of cycles until each cerclage loosened (residual tension <10 N) was recorded. RESULTS: All wires that failed did so by loosening. Twist cerclage cycled to 390 N and 290 N loosened within the first 10 cycles, and, when cycled to 100 N, they loosened by 250 cycles. All twist knots loosened by untwisting. Single-loop cerclage cycled to 320 N loosened within 10 cycles. At 240 N, 5 single-loop cerclage resisted 250 cycles before loosening. At 160 N, 2 of the 8 single-loop cerclage did not loosen by 100 000 cycles. When cycled to 640 N, one of the double-loop cerclage did not loosen following 500 000 cycles. When cycled to 480 N, 3 of the 8 wires did not loosen. CONCLUSION: Double-loop cerclage will be tighter and are better able to resist cycling than twist or single-loop cerclage. CLINICAL SIGNIFICANCE: Use of double-loop cerclage to stabilize bone fragments or prevent fissure propagation can be expected to provide greater resistance to loosening than twist or single-loop cerclage, both initially and with repeated loading.

Comparison of median sternotomy closure-related complication rates using orthopedic wire or suture in dogs: A multi-institutional observational treatment effect analysis.

OBJECTIVE: To determine and compare median sternotomy (MS) closure-related complication rates using orthopedic wire or suture in dogs. STUDY DESIGN: Multi-institutional, retrospective observational study with treatment effect analysis. ANIMALS: 331 client-owned dogs, of which 68 were excluded. METHODS: Medical records of dogs with MS were examined across nine referral centers (2004-2020). Signalment, weight, clinical presentation, surgical details, complications, and outcomes were recorded. Follow-up was performed using patient records and email/telephone contact. Descriptive statistics, treatment effect analysis and logistic regression were performed. RESULTS: Median sternotomy closure was performed with wire in 115 dogs and suture in 148. Thirty-seven dogs experienced closure-related complications (14.1%), 20 in the wire group and 17 in the suture group. Twenty-three were listed as mild, four as moderate and 10 as severe. Treatment effect analysis showed a mean of 2.3% reduction in closure-related complications associated with using suture versus wire (95% CI: -9.1% to +4.5%). In multivariable logistic regression, the only factor associated with increased risk of closure-related complications was dog size (p = .01). This effect was not modified by the type of closure used (interaction term: OR = 0.99 [95% CI: 0.96/1.01]). CONCLUSION: The incidence of closure-related complication after MS was low compared to previous reports. The likelihood of developing a closure-related complication was equivalent between sutures and wires, independent of dog size, despite a higher proportion of complications seen in larger dogs (≥20 kg). CLINICAL SIGNIFICANCE: Use of either orthopedic wire or suture appear to be an appropriate closure method for sternotomy in dogs of any size.

Polyaxial pedicle screw external fixation to stabilize oblique mandibular fractures in three standing, sedated horses.

OBJECTIVE: To report the radiographic, surgical and postoperative features in horses with unstable oblique mandibular fractures secured with polyaxial pedicle screws (PPS) external fixation construct and intraoral wiring. ANIMALS: Three client-owned horses. STUDY DESIGN: Short case series. METHODS: Two horses each had a unilateral fracture, which did not improve after conservative management, and one horse had bilateral fractures. Clinical and radiographic features were documented. Polyaxial pedicle screw external fixators and intraoral tension band wiring were applied in standing horses after combining sedation and regional nerve anesthesia. Intraoral wires were implanted through a lateral buccotomy between teeth (two horses) or burred through exposed crown (one horse) and then secured around the incisors. The PPS were inserted under radiographic guidance to avoid tooth roots. Healing was assessed with radiographic examination. The PPS external fixator rod and intraoral wires were removed first. The mandible was manipulated, and, if it was stable, the PPS were removed. RESULTS: Implants were removed at 6, 8, or 10 weeks after the mandibles were palpably stable. Complications included broken wires in one horse, bone sequestration in one horse, and infection in one horse. Follow-up communication with the owners 12 to 18 months later confirmed complete healing without further complications of the fractured mandibles or teeth. CONCLUSION: Polyaxial pedicle screw external fixation led to fracture healing and a return to function in all three horses. The complications encountered did not preclude a successful outcome. CLINICAL SIGNIFICANCE: Polyaxial pedicle screw external fixation coupled with intraoral wiring provides an alternative to treat unstable equine mandibular fractures without general anesthesia.

Influence of wire configuration on resistance to fragment distraction of tension bands placed in a greater trochanteric osteotomy model.

OBJECTIVE: To determine the influence of wiring configurations on initial tension and resistance to tensile loads in tension band constructs without the contributions of Kirschner-wire stabilization. STUDY DESIGN: Experimental study. SAMPLE POPULATION: A solid brass femur model manufactured on the basis of computed tomography of a normal right femur of a 30-kg dog modified by transection of the greater trochanter and placement of two pins that did not cross the simulated osteotomy. METHODS: Four tension band configurations were applied to the metal trochanteric osteotomy model: figure-of-eight with one twist (OT), figure-of-eight with two twists (TT), dual interlocking single loop, and double loop (DL). Configurations were tested under both monotonic loading (n = 8 per configuration) and incremental cyclic loading (n = 8 per configuration). Initial tension after tying, residual tension remaining after each cycle, and failure load at 2 mm of displacement (considered equivalent to clinical failure) were compared between configurations. RESULTS: The initial tension and the load to 2 mm of displacement were lower for OT wires compared with TT wires. The DL was the strongest and most stable configuration, generating 2.3 to 3.5 times greater initial tension, maintaining a greater percentage of residual tension under incremental cyclic loads, and resisting 2.0 to 2.4 times greater load before failure at 2 mm. Failure load was highly correlated with initial tension. CONCLUSION: Wire configurations reaching greater initial tension, such as the DL, allowed constructs to resist higher tensile loads. CLINICAL IMPACT: Wire configurations allowing higher initial tension may be warranted when tension bands are expected to sustain high tensile loads.

Minimally invasive percutaneous medial plate rod osteosynthesis for treatment of bicondylar humeral fractures in dogs: Surgical technique and case report.

OBJECTIVE: To describe a minimally invasive surgical technique for the treatment of comminuted humeral bicondylar (also known as T-Y) fractures in dogs and report outcome in 3 cases. STUDY DESIGN: Surgical technique description and case report. ANIMALS: Three consecutive dogs with traumatic comminuted humeral T-Y fractures. METHODS: Dogs that presented with a traumatic humeral T-Y fracture were prospectively included. The condylar component of the fractures was reduced first by using a combination of percutaneous forceps and K-wires. A transcondylar screw was applied, and epicondylar pins were preplaced medially and laterally. The metaphyseal component of the fracture was then reduced and stabilized with the pins. Finally, a bone plate was applied percutaneously along the medial humeral surface. Intraoperative fluoroscopy was used throughout surgery in all cases. Postoperative alignment in the frontal and sagittal planes was compared to the contralateral limbs. Time to clinical union, clinical outcome, and complications were recorded. RESULTS: Three dogs were included. Body weight ranged from 5.9 to 40 kg. Incomplete ossification of the humeral condyle was identified as the primary pathology leading to the fracture in 2 cases. All cases experienced uncomplicated healing with good to excellent functional recovery. CONCLUSION: The reported technique was associated with good outcomes without complications in 3 cases. CLINICAL SIGNIFICANCE: This study provides evidence that minimally invasive plate osteosynthesis represents an alternative to open reduction and internal fixation in the treatment of comminuted humeral T-Y fractures.

A biomechanical comparison of Kirschner-wire fixation on fracture stability in Salter-Harris type I fractures of the proximal humeral physis in a porcine cadaveric model.

BACKGROUND: The physis is the weakest component of immature long bones, and physeal fractures constitute about 30% of fractures in growing dogs. Fractures of the proximal humeral physis typically have a Salter Harris type I or II configuration. These fractures require accurate reduction and adequate stabilization to allow for any potential continued longitudinal bone growth, in conjunction with physeal fracture healing. Conventional internal fixation of these fractures involves insertion of two parallel Kirschner wires, although other methods described include tension band wiring, Rush pinning, and lag screws. However these recommendations are based on anecdotal evidence, and information about the biomechanical stability of physeal fracture repair is sparse. The unique anatomical structure of the epiphyseal-metaphyseal complex makes the gripping of the epiphysis for ex vivo biomechanical testing of physeal fracture repair very challenging. The objective of our study was to biomechanically assess the optimal number (three, two or one) of implanted Kirschner wires in a porcine Salter Harris I proximal humeral physeal fracture model, using motion analysis tracking of peri-fragmental retro-reflective markers while constructs were subjected to a constant axial compression and a sinusoidal torque of +/- 2 Nm at 0.5 Hz for 250 cycles. RESULTS: There were significant differences between the three constructs (three, two or one Kirschner wire repair) for gross angular displacement (p < 0.001). The difference between three pins and two pins on toggle was not significant (p = 0.053), but both three-pin and two-pin fixation significantly reduced rotational toggle compared to one-pin fixation. Construct stiffness was not significantly different between any of the pin groups (p > 0.33). CONCLUSIONS: Motion analysis tracking using peri-fragmental markers in this porcine model of physeal fracture repair found that the stability at the fracture site of one-pin fixation was significantly less than two-pin and three-pin fixation. Whether there was increased stabilization of these fractures with three-pin fixation compared to two-pin fixation was not conclusive in this porcine model.

Adjunct fixation with a Kirschner wire or a plate for lateral unicondylar humeral fracture stabilization.

OBJECTIVE: To compare the biomechanical properties of using an interfragmentary 1.6 mm Kirschner wire or a 2.7 mm reconstruction plate as adjunctive epicondylar stabilization in simulated comminuted lateral unicondylar humeral fractures stabilized with a transcondylar 4.5 mm cortical screw. STUDY DESIGN: Cadaveric biomechanical assessment. SAMPLE POPULATION: Paired humeri harvested from 9 young, skeletally mature dogs. METHODS: Simulated comminuted lateral unicondylar humeral fractures were stabilized with a transcondylar 4.5 mm cortical screw placed in lag fashion. Adjunct fixations consisting of a 1.6 mm Kirschner wire on one side, and a 2.7 mm reconstruction plate on the contralateral side, were tested within paired humeri. Repaired humeri were axially loaded to failure and construct stiffness, yield load, and load to failure were obtained from the load-deformation curves. RESULTS: Stiffness (mean ± SD: 577 ± 245 vs 310 ± 71 N/mm; P = .01), yield load (mean ± SD: 2389 ± 572 vs 1017 N ± 292; P = .0002), and load at failure (mean ± SD: 3351 ± 358 vs 1693 ± 363 N; P = .009) were greater in constructs incorporating a reconstruction plate rather than a Kirschner wire. CONCLUSION: Our results support the recommendation for adjunct fixation of comminuted lateral unicondylar humeral fractures with an epicondylar plate.

Complete longitudinal patellar fracture in a cat: A rare case.

Longitudinal patellar fractures in cats are extremely rare with only 1 other report of a comminuted longitudinal fracture for which pins and wires were placed in the patella for stabilization. This report describes the surgery and outcome of a strictly longitudinal patellar fracture in a cat.

Fracture patellaire longitudinale complète chez un chat : un cas rare. Les fractures patellaires longitudinales chez les chats sont extrêmement rares et seulement un autre rapport de fracture longitudinale fragmentée a été publié pour lequel des broches et fils ont été placés dans la rotule afin de la stabiliser. Ce rapport décrit la chirurgie et les résultats d'une fracture patellaire strictement longitudinale chez un chat.(Traduit par Isabelle Vallières).

Angular Limb Deformities: Growth Retardation.

Angular limb deformities are common in foals; however, the importance of the deformity and if treatment is required depend on the degree of deformity relative to normal conformation for stage of growth, the breed and discipline expectations, age, and response to conservative therapies. This article addresses the importance of the foal conformation examination to determine which foals need surgical intervention to correct an angular deformity and when. Techniques for surgical growth retardation include the transphyseal staple, screw and wire transphyseal bridge, and transphyseal screw. Appropriate timing for intervention for each location and complications associated with each procedure are discussed.

REPAIR OF A FEMORAL FRACTURE IN A CONGO AFRICAN GREY PARROT ( PSITTACUS ERITHACUS ERITHACUS) WITH A PARACORTICAL-CLAMP-CERCLAGE TECHNIQUE.

A 1-yr-old female Congo African grey parrot ( Psittacus erithacus erithacus) was admitted with a lameness of the right pelvic limb. On the radiographs a closed, caudolaterally displaced, comminuted, diaphyseal fracture of the femur was diagnosed. Surgery under general anesthesia was performed in order to repair the fracture with a paracortical-clamp-cerclage technique. This straightforward and effective technique has been developed as a low-cost treatment for simple and comminuted diaphyseal fractures in dogs and cats. Fixation is obtained with clamps, shaped during surgery, and attached to the bone shaft with cerclage wire. This technique led to immediate weight-bearing, appropriate bone healing, and permanent fixation of the implants in the patient. To the best of the authors' knowledge, this case represents the first report of a surgical repair of a femoral fracture with a paracortical-clamp-cerclage technique in a bird.

A simple technique to repair a hand fracture in a captive Siamang.

A 5-year-old female Siamang (Hylobates syndactilus) in captivity sustained a displaced closed fracture of the proximal phalanx of the middle digit, resulting in finger deformity and hand functional disability. Anatomical reduction and stabilization of the fracture were obtained surgically using two multifilament wire sutures. The primate had a successful functional recovery.

Mechanics of Supplemental Drop Wire and Half-Pin Fixation Elements in Single Ring Circular External Fixator Constructs.

OBJECTIVE: Evaluate the effects of supplemental fixation elements on the mechanical properties of a single ring circular fixator construct. STUDY DESIGN: In vitro mechanical testing. SAMPLE POPULATION: Five construct configurations (six replicates of each configuration) were used to stabilize a 1.6 cm diameter Delrin rod bone model. METHODS: Constructs were assembled using 66 mm complete rings, 1.6 mm olive wires, and 3.2 mm diameter half-pins. Construct configurations tested were a base single ring construct, constructs with 1 supplemental drop wire or constructs with 1, 2, or 3 supplemental half-pins. Constructs were loaded in axial compression, caudocranial and mediolateral bending, and torsion. Strain was measured in individual fixation elements during axial loading. RESULTS: A supplemental drop wire or half-pin significantly increased bending and torsional stiffness. The supplemental half-pin increased caudocranial stiffness significantly more than placing a drop wire. Placing a 2nd or 3rd pin afforded significantly greater increases in construct stiffness in all modes of loading, with 3 half-pin constructs having significantly greater axial and caudocranial stiffness than 2 half-pin constructs. Placing a single supplemental pin induced cantilever bending resulting in angular displacement of the Delrin rod during axial loading and high strain in both the fixation wire secured distal to the ring and the pin. Supplemental half-pins incrementally reduced strain in all fixation elements and resulted in linear displacement of the Delrin rod during axial loading. CONCLUSION: If using supplemental half-pins as fixation elements, insertion of 2 or 3 pins is preferred over a single pin.

Effect of fixation method on postoperative complication rates after surgical stabilization of lateral humeral condylar fractures in dogs.

OBJECTIVES: To assess the impact of stabilization method on the complication rate after lateral humeral condylar fracture (LHCF) repair. STUDY DESIGN: Retrospective multicenter clinical cohort study. ANIMALS: Dogs (n = 151) with LHCF. METHODS: Medical records (2004-2012) were reviewed for dogs that had surgical repair of LHCF. Data retrieved included signalment, cause of fracture, evidence of incomplete ossification of the humeral condyle, occurrence of postoperative complications, presence of supracondylar comminution preoperatively, and persistence of an intracondylar fissure postoperatively. Outcome was assessed based on the most recent data available and graded as excellent, good, fair, or poor. RESULTS: LHCF (n = 135) were evaluated in 132 dogs; 61 fractures were stabilized using a transcondylar screw and supracondylar K-wire, 13 using a transcondylar screw and supracondylar screw, and 61 using a transcondylar screw and lateral epicondylar plate. Major complications were significantly (P = .01) more common after stabilization using a transcondylar screw and supracondylar K-wire (28%) than in dogs where a supracondylar screw or lateral epicondylar plate were used (11%). Cases that had postoperative complications were significantly (P = .02) more likely to have a poor outcome. CONCLUSIONS: LHCF stabilized using a transcondylar screw and supracondylar K-wire are more likely to have major complications resulting in a poorer outcome than cases stabilized using a supracondylar screw or lateral epicondylar plate.

Surgical repair of mandibular symphyseal fractures in three silver arowana (Osteoglossum bicirrhosum) using interfragmentary wire.

Three silver arowana (Osteoglossum bicirrhosum) were presented with unstable fractures of the mandibular symphyses. Surgical repair was performed to reduce and stabilize the fractures using interfragmentary wire. The fish returned to light feeding at 2 days and normal feeding at 5 days postsurgery. The wires were removed at 6 wk postsurgery with good alignment of the mandibular symphyses and stable fracture sites. There had been no further complications at the time of writing 18 wk postsurgery.

K-wire is more damaging than standard or acrylic drill bits when evaluating torsional properties of rabbit (Oryctolagus cuniculi) femurs.

OBJECTIVE: The objective of this study is to compare drilling variables and torsional mechanical properties of rabbit femora after bicortical drilling with a 1.5-mm standard surgical drill bit, acrylic drill bit, and K-wire. SAMPLES: 24 pairs of rabbit femora. METHODS: After drilling under controlled axial displacement rate, each bone was biaxially loaded in compression followed by rapid external torsion to failure. Maximum axial thrust force, maximum drill torque, integral of force and displacement, change in temperature, maximum power spectral density of the torque signal, torque vibration, and torque and angle at the yield and failure points were collected. Pre- and postyield stiffness, yield and failure energies, and postyield energy were calculated. RESULTS: The work required to drill through the cis- and transcortices (integral of force and displacement) was greater for the K-wire, followed by the acrylic and then standard drill bits, respectively. The K-wire demonstrated higher maximum torque than the drill bits at the ciscortex, and the force of drilling was significantly greater. The vibration data was greater with the acrylic and standard drill bits than the K-wire. There was no difference in torsional strength between drilling types. CLINICAL RELEVANCE: Mechanical differences exist between different drill bits and K-wire and demonstrate that the K-wire is overall more damaging than the surgical drill bit.

A biomechanical evaluation of three drop wire configurations.

OBJECTIVE: Evaluate effect of adding drop wires to single-ring constructs. STUDY DESIGN: Biomechanical study SAMPLE POPULATION: Single ring circular external skeletal fixator constructs stabilizing a Delrin segment bone model. METHODS: Eight replicates of 5 constructs made with 66 mm complete rings, 1.6 mm olive wires, and a 15.9-mm diameter Delrin rod were loaded in axial compression, craniocaudal and mediolateral bending, and torsion. Constructs tested were: (1) base single-ring construct; (2) single-ring construct with a drop wire mounted on fixation bolts; (3) single-ring construct with a drop wire mounted on 1-hole posts; (4) single-ring construct with a drop wire mounted on 2-hole posts; and (5) 2-ring construct. Construct stiffness for each mode of loading was compared using repeated measures ANOVAs (P ≤ .05). RESULTS: Axial compression and torsion: the 2-ring construct was stiffer than all others. Drop wire constructs were stiffer than the single-ring construct, but not significantly different from each other. Craniocaudal bending: the 2-ring construct was stiffest with the 2-hole post construct being stiffer than all except the 2-ring construct. Mediolateral bending: the 2-hole post construct was stiffer than the 2-ring construct, which was stiffer than the 1-hole post construct, which was stiffer than the fixation-bolt construct, which was stiffer than the single-ring construct. CONCLUSIONS: Drop wires improved stiffness of single-ring constructs in all loading modalities. Positioning the drop wire farther from the ring surface significantly improved craniocaudal and mediolateral bending stiffness, but did not affect axial compression and torsional stiffness.

Repair of a canine patellar ligament rupture using the ComPact UniLock 2.4/3.0 mm System.

An 11-year old, female, Mix Breed dog was presented after being hit by a car with a rupture of the left patellar ligament. Due to a suspected wound infection close to the stifle joint, surgical repair was delayed for 10 days. The ruptured ligament was sutured and augmented with fascia lata. Additionally, two ComPact UniLock 2.4/3.0 mm plates connected with 1.0 mm orthopaedic wire were used to protect the primary repair. No immobilization of the stifle joint was needed. The implants were removed after 7 weeks, because of suspected infection and loosening. The successful utilization of an alternative surgical technique for the repair of the patellar ligament rupture in the dog has also been documented by pre- and post-operative temporal-spatial gait analysis (GaitFour®).