Short-term outcomes and complications of 65 cases of porous TTA with flange: a prospective clinical study in dogs.

BACKGROUND: Cranial cruciate ligament rupture (CrCLR) is the most common orthopaedic cause of lameness in the hind limb in dogs. Many surgical treatments have been described, but tibial tuberosity advancement (TTA) is one of the most commonly used today. Since it was first described, TTA has evolved to reduce major complications and to arrest the progression of osteoarthrosis. The aim of this study was to assess a surgical technique called Porous TTA with flange prospectively. This study was performed in 61 dogs that underwent 65 Porous TTA with flange procedures, to validate it as an alternative CrCLR treatment. Complications and clinical outcomes (pain, lameness, weight bearing, flexion, extension, crepitation and atrophy) were reported over 3 months, i.e. at 3, 6 and 12 weeks postoperatively. RESULTS: The results showed a positive clinical outcome, a minor complication rate of 47.69% at the first review 3 weeks postoperatively, 10.77% at the second one (6 weeks after the surgery) and 4% at the third one (at 12 weeks). Major complications were observed only at the last review, with one case that had an infection requiring implant removal; this represented 1.5% of cases. Variables evaluated for a relationship with complication scores and improvement were body condition score, sex, age, breed, body weight, breed size, side of the affected limb, traumatic anamnesis and time of lameness before surgery. No relationship was detected. CONCLUSIONS: Clinical outcomes and complications show that Porous TTA with flange is an efficient alternative for surgical treatment of CrCLR in dogs.

Incidence of support limb laminitis in horses treated with half limb, full limb or transfixation pin casts: a retrospective study of 113 horses (2000-2009).

REASONS FOR PERFORMING STUDY: To determine the incidence of support limb laminitis among horses treated with half limb, full limb or transfixation pin casts and determine potential risk factors. METHODS: Medical records of 113 horses treated with half limb, full limb or transfixation pin casts at an equine referral hospital from 2000 to 2009 were reviewed. Associations between potential risk factors and development of support limb laminitis were evaluated by bivariable and multivariable logistic regression analyses. RESULTS: Of the 113 horses that received casts, 14 (12%) developed confirmed support limb laminitis. The bodyweight of the horse and duration of casting in weeks were significantly associated with support limb laminitis. Horses requiring full limb casts or transfixation pin casts were more likely to develop this complication than horses requiring half limb casts. There were no significant associations between developing support limb laminitis and weightbearing capacity on presentation to the hospital, the limb affected (fore- or hind), whether there was a fracture present or breed of horse. CONCLUSIONS: Support limb laminitis is a relatively common complication among horses treated with half limb, full limb and transfixation pin casts. Greater durations of casting and higher bodyweights increase the likelihood of developing this complication. POTENTIAL RELEVANCE: Support limb laminitis may occur secondary to any painful unilateral lameness and is not necessarily more likely to develop in horses with severe orthopaedic conditions such as fractures. However, heavier horses, those requiring casts for longer periods of time and those that require a full limb or transfixation pin cast as opposed to a half limb cast should be considered to have an increased risk for developing support limb laminitis post operatively.

Surgical treatment of disk-associated wobbler syndrome by a distractable vertebral titanium cage in seven dogs.

OBJECTIVE: To evaluate a distractable titanium cage for the treatment of disk-associated wobbler syndrome (DAWS). STUDY DESIGN: Prospective study. ANIMALS: Dogs (n = 7) with DAWS. METHODS: After total discectomy of C5-C6 and C6-C7, the median part of the vertebral body of C6 was removed with preservation of the lateral walls and dorsal cortex. The removed cancellous bone was collected. The implant was placed in the bony defect of C6. After placement, the titanium cage was distracted and affixed by 4 screws. Finally, the implant was filled and covered with cancellous bone. Dogs had follow-up examinations at 1, 3, 6, 12, and 24 months. Six months after surgery, cervical radiographs and computed tomography (CT) were performed. RESULTS: Although no intraoperative complications occurred, correct placement of the cage was technically challenging. Revision surgery was necessary in 2 dogs because of implant loosening and aggravation of vertebral tilting. All dogs improved after discharge from the hospital. In 1 dog, recurrence of clinical signs caused by articular facet proliferation at an adjacent intervertebral disk space occurred. Radiographs at 6 months demonstrated cage subsidence in 4 dogs. In all dogs, CT was suggestive for fusion of the bone graft with the vertebral body. CONCLUSIONS: Although results are promising, technical adaptations will be necessary to make this specific surgical technique, designed for humans, suitable for routine use in dogs.

Theoretical discrepancy between cage size and efficient tibial tuberosity advancement in dogs treated for cranial cruciate ligament rupture.

OBJECTIVES: To calculate the difference between the desired tibial tuberosity advancement (TTA) along the tibial plateau axis and the advancement truly achieved in that direction when cage size has been determined using the method of Montavon and colleagues. To measure the effect of this difference on the final patellar tendon-tibial plateau angle (PTA) in relation to the ideal 90°. METHODS: Trigonometry was used to calculate the theoretical actual advancement of the tibial tuberosity in a direction parallel to the tibial plateau that would be achieved by the placement of a cage at the level of the tibial tuberosity in the osteotomy plane of the tibial crest. The same principle was used to calculate the size of the cage that would have been required to achieve the desired advancement. The effect of the difference between the desired advancement and the actual advancement achieved on the final PTA was calculated. RESULTS: For a given desired advancement, the greater the tibial plateau angle (TPA), the greater the difference between the desired advancement and the actual advancement achieved. The maximum discrepancy calculated was 5.8 mm for a 12 mm advancement in a case of extreme TPA (59°). When the TPA was less than 31°, the PTA was in the range of 90° to 95°. CLINICAL SIGNIFICANCE: A discrepancy does exist between the desired tibial tuberosity advancement and the actual advancement in a direction parallel to the TPA, when the tibial tuberosity is not translated proximally. Although this has an influence on the final PTA, further studies are warranted to evaluate whether this is clinically significant.

Ex vivo comparison of a novel tapered-sleeve and traditional full-limb transfixation pin cast for distal radial fracture stabilization in the horse.

Distal radial fractures in adult horses are examples of long-bone fractures that are not always amenable to internal fixation. These fractures are often open, contaminated, severely comminuted, and located adjacent to the antebrachiocarpal joint. There have been few studies to improve upon the methods of stabilization of this type of fracture. External coaptation incorporating transfixation pins is one method that has been used to stabilize distal radial fractures in horses (1-3). The purpose of this preliminary study was to compare the load to failure in simulated weight-bearing of a novel tapered-sleeve transfixation pin cast (TSTPC) (4) with the traditional transfixation pin cast (TPC) in an ex vivo distal radial fracture model. Ten adult equine cadaveric forelimbs were randomly placed into a TPC group (n = 5) or a TSTPC group (n = 5). An oblique distal radial osteotomy was created prior to application of fibreglass cast material. The limbs were loaded in a single cycle to failure in simulated weight-bearing using an axial load. The mean load to failure for the TSTPC group (35,814 N) was significantly greater than in the TPC group (22,344 N) (p = 0.003). Tapered sleeves in conjunction with TPC warrant further investigation because they may prolong the life of the fixation, prevent or diminish fractures through the pin sites, and increase the load capacity of external coaptation used to stabilize equine fractures.

Mechanical analysis of fixation methods for anterior cruciate ligament reconstruction with hamstring tendon graft. An experimental study in sheep knees.

This study evaluates the structural properties of the femur-anterior cruciate ligament (ACL) graft-tibia complex, comparing different graft fixation techniques in sheep knees. Four fixation devices were tested both for femoral fixation (Transfix, absorbable screw, RCI screw and Linx-HT) and tibial fixation (bone plug with metal screw, absorbable screw with staple, RCI screw and cancellous screw with spiked washer). The graft used for ACL reconstruction was fresh ovine doubled Achilles tendon (DAT). Femurs and tibias were tested separately. Two mechanical test series were performed on the specimens: a load-to-failure test and a cyclic loading test. On the femoral side, transcondylar screw showed the greatest fixation strength and stiffness and the lowest elongation at cyclic loading. Tibial fixation complexes seemed to have poorer structural properties in comparison to femoral fixation. Among the tibial fixation devices, absorbable screw with staple fixation showed the greatest strength and stiffness. Spiked washer fixation showed the greatest elongation under cyclic loading.

Tension band stabilization of fractures and luxations of the thoracolumbar vertebrae in dogs and cats: 38 cases (1993-2002).

OBJECTIVE: To determine the outcome of dogs and cats in which a tension band technique was used to stabilize traumatic fractures and luxations of the thoracolumbar vertebrae. DESIGN: Retrospective study. ANIMALS: 38 client-owned animals (22 dogs and 16 cats) weighing between 1.4 and 45 kg (3 and 99 lb). PROCEDURE: Medical records of cats and dogs that underwent tension band stabilization of thoracolumbar fractures and luxations at the University of Zurich between 1993 and 2002 were reviewed. The stabilization technique was a modification of a spinal stapling technique with a figure 8 hemicerclage wire placed in a tension band fashion across the lesion. Neurologic status, lesion location and type, and concomitant traumatic injuries were assessed from the medical records and preoperative radiographs. Clinical outcome and complications were determined through follow-up examinations or telephone conversations with the owners. RESULTS: Complete or satisfactory neurologic recovery was achieved in 30 (79%) patients. Seven patients were euthanatized (6 owing to poor neurologic recovery and 1 owing to implant failure), and 1 dog was managed at home despite paraplegia. Clinically, only 4 patients (11%) had evidence of implant or fixation failure; all were dogs weighing > 16 kg (35 lb). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the tension band technique may be appropriate for stabilization of fractures and luxations of the thoracolumbar vertebrae in cats and small- or medium-sized dogs. In larger dogs, fixation strength may be insufficient to stabilize certain fracture types and ancillary external or internal fixation methods may be needed.

Influence of bolt tightening torque, wire size, and component reuse on wire fixation in circular external fixation.

OBJECTIVES: To evaluate the effects of bolt torque, wire size, and component reuse on the ability to maintain wire tension in 3 external skeletal fixation systems. STUDY DESIGN: Biomechanical study. METHODS: Yield strength in tension of 1.0-, 1.2-, 1.5-, and 1.6-mm-diameter wires, and yield strength in torque of Hofmann Small Bone Fixation (SBF) cannulated and slotted bolts and IMEX regular and miniature bolts were determined on a testing machine. The minimum bolt tightening torque needed to prevent wire slippage at clinically recommended wire tensions was determined. Components were tested 10 times, and loads at slippage were recorded. RESULTS: The IMEX system required a mean of 8 Nm of bolt tightening torque to maintain 900 N (1.6-mm wires). The SBF system required a mean of 3 Nm bolt torque to maintain 300 N (1.0-mm wires) and 5 Nm to maintain 600 N (1.2-mm wires). The SBF cannulated bolt required 9 Nm of torque to maintain 900 N (1.5-mm wires). The SBF slotted bolts could only maintain 800 N before yield. The IMEX miniature system required a mean bolt torque of 1.1 Nm to maintain 300 N. The cannulated and slotted bolts from both manufacturers failed to maintain 70% of initial wire tension after 7 and 4 uses, respectively. CONCLUSIONS: The IMEX systems and the SBF system using 1.0- and 1.2-mm wires could maintain clinically recommended wire tension safely. Only the IMEX system could maintain clinically recommended wire tension safely using 1.5- or 1.6-mm wires. CLINICAL RELEVANCE: The SBF system using 1.0- and 1.2-mm wires and the IMEX system using all wire sizes can maintain clinically relevant wire tension. The SBF system using 1.5-mm wires could not. Cannulated and slotted bolts should not be used more than 6 and 3 times, respectively. Nuts should not be reused.

In vitro comparison of transfixation and standard full-limb casts for prevention of displacement of a mid-diaphyseal third metacarpal osteotomy site in horses.

OBJECTIVE: To compare transfixation and standard full-limb casts for prevention of in vitro displacement of a mid-diaphyseal third metacarpal osteotomy site in horses. SAMPLE POPULATION: 6 forelimbs from 6 horses euthanatized for reasons not related to the musculoskeletal system. PROCEDURE: A 30 degrees osteotomy was performed in the mid-diaphysis of the third metacarpal bone. Two 4.5-mm cortical bone screws were placed across the osteotomy site to maintain alignment during casting. Two 6.35-mm Steinmann pins were placed from a lateral-to-medial direction in the distal aspect of the radius. A full-limb cast that incorporated the pins was applied. An extensometer was positioned in the osteotomy site through a window placed in the dorsal aspect of the cast, and after removal of the screws, displacement was recorded while the limb was axially loaded to 5,340 N (1,200 lb). Pins were removed, and the standard full-limb cast was tested in a similar fashion. RESULTS: The transfixation cast significantly reduced displacement across the osteotomy site at 445 N (100 lb), 1,112 N (250 lb), 2,224 N (500 lb), and 4,448 N (1,000 lb), compared with the standard cast. CONCLUSION AND CLINICAL RELEVANCE: A full-limb transfixation cast provides significantly greater resistance than a standard full-limb cast against axial collapse of a mid-diaphyseal third metacarpal osteotomy site when the bone is placed under axial compression. Placement of full-limb transfixation casts should be considered for the management of unstable fractures of the third metacarpal bone in horses.

Management of cervical spondylopathy-associated intervertebral, disc protrusions using metal washers in 78 dogs.

Intervertebral 7.5 mm (n = 75) and 6.0 mm (n = 22) metal washers were used to distract intervertebral spaces in 78 consecutive cases of canine cervical spondylopathy-associated disc protrusions, where myelography had demonstrated traction-responsive spinal cord compression. Nineteen dogs had compressive lesions at two sites. Fifty lesions were evaluated myelographically on immediate postoperative radiographs; of these, 32 compressions had been eliminated and 18 had been reduced. Euthanasia was performed in nine dogs within six months of surgery and 15 dogs had varying degrees of neck pain during this period. Long-term follow-up information was available on 65 dogs nine to 70 months following surgery (median 32 months). Sixty-three of these dogs improved postoperatively. Neurological function subsequently deteriorated in 17 dogs 10 to 59 months following surgery (median 34 months). Eight of these 17 cases had further myelographic investigations and all had additional disc protrusions with no evidence of cord compression at the previous sites of surgery. The remaining nine cases had a deterioration in hindlimb function but were not investigated further.

In vitro mechanical properties of different equine hoof wall crack fixation techniques.

Hoof wall cracks need mechanical stabilisation to allow healing. Common techniques are fixation with screws, wires and plates or bonding of a patch across the crack. An in vitro system to determine the shear properties of equine hoof crack repairs is described. The force and displacement at yield, stiffness and ultimate force were determined for 4 repair techniques based on an acrylic material, polyurethane patch attached with cyanoacrylate adhesive, steel plate attached with screws and a transverse metal bar cut into the hoof wall. The cyanoacrylate bonded patch repair had lower values for all parameters measured (n = 8, P<0.05) and the other 3 repairs had similar mechanical properties. This study demonstrates that acrylic adhesive repairs can resist similar shear forces to traditional screw plate repairs without risk of penetrating into the sensitive structures of the foot. The transverse bar mounted across the crack had similar resistance to shear as the much larger screw plate and plain bonding repair techniques. This novel technique may be a useful adjunct to other repair methods.

Instrumentation and techniques in equine fracture fixation.

In recent years fracture fixation in the horse has changed significantly. New devices, mainly adapted from the human field, have been successfully introduced into large animal surgery. Examples of such implants include the DCS/DHS implant system, the self-tapping screw, the cannulated screw, and the pinless external fixator. However, new devices have also been developed exclusively for equine fracture management, including the interlocking intramedullary nail and the external skeletal fixation device. With these devices the surgeon has more options for repairing fractures in horses. Nevertheless, many problems are still unsolved. Indications exist that during the next few years new, exciting fracture fixation systems will be developed, providing further advancements in the quest for the ideal implant for horses. However, the development stages of these devices are such that mentioning the possibilities here is premature.

In vitro comparison of the standard short limb cast and three configurations of short limb transfixation casts in equine forelimbs.

Axial stability of equine oblique proximal phalangeal osteotomies with application of the standard short limb cast or 1 of 3 configurations of transfixation casts was determined in vitro. Transfixation cast methods included use of parallel pins, divergent pins, or parallel pins incorporating a metal walking bar. Displacement at the osteotomy was recorded for each limb at 4,448 N. Standard short limb casts provided significantly (P = 0.0002) less axial stability than did any form of transfixation cast. Significant differences were not found between the 3 transfixation casts.

Conservative management of fractures of the mandibular condyloid process in three cats and one dog.

Three cats and 1 dog with fracture of the mandibular condyloid process and concomitant fracture(s) of the rostral portion of the mandible were treated successfully by wire fixation of the rostral mandibular fracture(s) and by conservative management of the mandibular condylar fracture. All animals regained satisfactory dental occlusion and normal, pain-free motion of the jaw. Fracture of the mandibular condyloid process is an infrequently diagnosed injury that usually occurs with other mandibular fractures. If satisfactory dental occlusion can be achieved by surgical stabilization of the noncondylar fractures, surgical repair of the mandibular condyloid fracture may not be necessary.

Use of an aiming device for application of a type-II (bilateral) external fixator to a fractured tibia of a dog.

An aiming device was used to guide insertion of fixation pins in a type-II (bilateral) external fixator stabilizing an open canine tibial fracture. This device, designed by the Swiss AO group, has multiple applications in orthopedic surgery, because it accurately locates the exit point of a pin or drill hole on the far side of a bone or fractured bone fragment. When used with the type-II external fixator, it greatly facilitates pin placement by ensuring that, as a pin emerges from the bone, it is in line with the second clamp on the opposite connecting bar.

Effect of cerclage wires on periosteal bone in growing dogs.

Three diameters of wire were placed circumferentially around the femora of six 22 week old puppies. The wires were placed over the periosteum on one limb and under the periosteum on the other limb. The effect of the wires on actively growing bone was evaluated 3 and 8 weeks after placement. Diffuse growth of periosteal new bone occurred in immature dog femora in which cerclage were placed under the periosteum. This reaction corresponded with dramatically increased medullary and periosteal microvascularity coupled with histologic active trabecular bone formation. In femora in which wires were placed over the periosteum, even though the placement of the wires should supposedly have been the most detrimental, there were active vessels within the cortex directly under all wires. In both preparations, cerclage wires were becoming encased in the growing cortical bone 8 weeks after placement. Cerclage wires did not devitalize immature bone nor did it restrict adjacent appositional bone growth.

[Simple surgical treatment of hip dislocation in dogs and cats using a modified toggle]. / Eenvoudige operatieve behandeling van heupluxaties bij hond en kat door middel van een gemodificeerde toggle.

Surgical treatment of dislocations of the hip by a modified toggle as described by Knowles (1953) usually results in a very rapid and permanent restauration of function to normal. An essential feature of this method is the slight surgical injury. This is achieved by using a relatively small toggle and drills with small diameter. The surgical technique and the results of treatment in 18 cats and 10 dogs are reported.