Fixation of cancellous bone and physeal fractures with biodegradable rods of self-reinforced polylactic acid

The frequent need for removal of metallic implants after fracture healing, has stimulated research into biodegradable osteosynthesis materials. The ideal biodegradable implant should support the fracture during healing and would slowly lose strength as the bone became able to resist the distracting forces. Decades of research into biodegradable materials has given much information on biocompatibility, degradation rates and processability of resorbable polyglycolides and polylactides. This has aided the development of an ultra high strength self-reinforcing composite construction allowing the manufacture of implants for several purposes. This study tested the use of self-reinforced poly-1-lactic acid rods for the fixation of cancellous fractures and osteotomies in 20 fixations in dogs and cats. The operating technique, callus formation, healing pattern, and functional and radiological end result, were evaluated. Two fixations failed but the functional end result was judged to be excellent in all but one of the healed cases. There was no need for surgery to remove the implants.     

Repair of radial fractures in toy breed dogs with self-reinforced biodegradable bone plates, metal screws, and light-weight external coaptation

OBJECTIVE: To describe a surgical technique for, and outcome after, treatment of radial fractures with biodegradable self-reinforced polylactide plates and metal screws, and external coaptation. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Eleven Toy breed dogs. METHODS: Radial fractures were repaired by application of a single or 2 stacked biodegradable self-reinforced polylactide plates (poly-L/D, L-lactide, stereocopolymer [LL-and DL-lactide ratio 70/30]; SR-PLA (70/30) implants) secured with metal screws, and light-weight external coaptation. Healing was evaluated clinically and by radiography at 2, 4, 6, 8, 9, 12, 24-26 weeks, and at 1 and 2 years. Owners were interviewed 3 years after surgery. RESULTS: Radial fracture lines disappeared within 4-14 weeks in 10 dogs; an implant failed in 1 dog. Ambulation was excellent for healed fractures. Excessive skin tension led to removal of implants in 1 dog and suture repair in another dog. No foreign body reaction from implant degradation was observed and the plate was usually no longer palpable at 2 years. One dog had a fracture through a screw hole at 1 year. CONCLUSION: Healing and complication rates after repair of radial fractures with SR-PLA (70/30) plates were considered similar or better than reported after repair with metallic plates or external fixation in Toy breed dogs. No radiographic signs of osteopenia were identified under the plate during follow-up. CLINICAL RELEVANCE: Biodegradable polylactide plates could be considered as an alternative to metal plates for radial fracture repair in Toy breed dogs, however available plates are likely not strong enough when used as a single plate. Implant removal is usually not needed.     

Treatment of distal diaphyseal fractures using hybrid external skeletal fixation in three dogs

Stabilisation of distal diaphyseal/metaphyseal fractures or osteotomies of the tibia and the radius is challenging due to the small fragment size, with innovative implants and external skeletal fixation systems described for their management. Hybrid external skeletal fixation is a novel external fixation system for use in small animals. This case series describes the management of distal diaphyseal fractures with IMEX-SK hybrid external skeletal fixation in three canine patients. Fracture healing was achieved in all cases, with frame removal after 5 to 10 weeks. Minimal complications were encountered in two cases. IMEX-SK hybrid external skeletal fixation constructs provide the veterinary surgeon with another option in the management of distal diaphyseal/metaphyseal fractures.     

Intramedullary nailing of diaphyseal fractures with self-reinforced polylactide implants

In fracture treatment, several adverse effects of metal, especially its excessive rigidity, often require the removal of the implants after a fracture has healed. Recent research with biodegradable polymers has contributed to the development of totally biodegradable polylactic acid implants with very high initial bending and shear strengths, but a modulus of elasticity comparable to that of bone. These implants were originally intended for use in fractures involving cancellous bone. Encouraging results from treating experimentally produced diaphyseal fractures led the authors to use these implants in a clinical trial on shaft fractures in dogs and cats. In this study, a total of 11 dogs and 14 cats had 28 diaphyseal fractures treated with one or several intramedullary pins of self-reinforced left isomeric polylactic acid. Of the 25 treated cases, 23 healed. Four of these had an unsatisfactory end result attributed to the implants used and one developed an osteomyelitis. Thus, out of 25 fractures, 23 united (92 per cent] and 18 [72 per cent) had a good or excellent outcome.     

Fixation of Cancellous Bone and Physeal Fractures in Dogs and Cats. A Comparison of the Use of Self-reinforced Biodegradable Devices to the Use of Metallic Devices and External Fixations

The use of self-reinforced biodegradable devices made of polyglycolide in the cancellous bone and physeal fractures of dogs and cats was compared to the use of metallic devices and external fixations on similar fractures. The series consisted of 64 dogs and 22 cats divided into 6 comparable groups. The patients in the 2 groups fixed with biodegradable devices started to use their operated limbs earlier than in the other groups. The same 2 groups also healed clinically (showed no lameness) earlier than the other groups. Radiographically there was no statistical difference between the 6 groups.On the basis of this study it may be concluded that the fixation with self-reinforced biodegradable devices is as suitable for the fixation of cancellous bone and physeal fractures of dogs and cats as the fixation with metallic devices or external fixation. This biodegradable technique has additional benefits allowing the patients to feel less pain in their operated limbs and making secondary operations to remove the devices unnecessary.     

Treatment of tibial fractures with plates using minimally invasive percutaneous osteosynthesis in dogs and cats

OBJECTIVES: The aim of the here described case series was to develop and evaluate the minimally invasive percutaneous osteosynthesis for the plate fixation of tibial fractures in dogs and cats. METHODS: Six dogs and four cats with shaft fractures of the tibia were treated using minimally invasive percutaneous osteosynthesis. Follow-up radiographs four to six weeks after fracture fixation were evaluated for fracture healing. For the long-term follow-up (minimum 2.4 years), owners were contacted by phone to complete a questionnaire. RESULTS: All fractures healed without the need for a second procedure. Follow-up radiographs obtained after four to six weeks in seven cases showed advanced bony healing with callus formation and filling of the fracture gaps with calcified tissue in all seven. All the patients had a good to excellent long-term result with full limb function. The time needed for regaining full limb use was two to three months. CLINICAL SIGNIFICANCE: Minimally invasive percutaneous osteosynthesis seems to be a useful technique for the treatment of tibial shaft fractures in dogs and cats.     

Principles of intramedullary pin and wire fixation

Knowledge and experience in the proper use of IM pins, K-wires, and orthopedic wire is a valuable asset to the veterinarian's ability to successfully repair a variety of long bone fractures. Most long bone fractures are amenable to repair with this form of fixation. When the principles of application are violated or the implants are used when contraindicated, complications often occur. Proper use of these implants results in the successful management of complex fractures to the satisfaction of both the animal owner and the veterinarian (Fig 10).     

Miniplate Fixation for Repair of Mandibular and Maxillary Fractures in 15 Dogs and 3 Cats

Maxillofacial miniplates and screws were used for skeletal fixation in 15 dogs and 3 cats that sustained a variety of mandibular and maxillary fractures. These implants were used as neutralization or buttress fixation in 11 caudal (junction of the ramus with the mandibular body) and 2 rostral mandibular fractures, 4 maxillary fractures, and 2 zygomatic arch fractures. All but one of the fractures healed with appropriate occlusion and excellent function. In one case of a rostral mandibular fracture, soft tissue dehiscence occurred accompanied by a loss of the fixation and subsequent distraction of the bone fragments; reasonable function was obtained by performing a rostral mandibulectomy. Plate contouring and application of the miniplates along the appropriate biomechanical lines of stress was easily performed and permitted the biomechanical principles of tension band fixation to be applied in most cases. Miniplate fixation, either used alone or in combination with other fracture fixation techniques, achieved sufficiently rigid skeletal fixation to provide uncomplicated healing and good to excellent functional and cosmetic results in 14 dogs and 3 cats.     

Treatment of fractures of the mandible and maxilla by mini titanium plate fixation systems in dogs and cats

Mini titanium plates were used to repair certain fractures of the maxilla and mandible in dogs and cats, under general anaesthesia. The location of the fractures treated were: corpus mandible, one dog; corpus mandible and symphysis, two dogs; caudal mandible, two dogs; rostral mandible, one dog; maxilla, one dog; nasal bone, one dog; corpus mandible and symphysis, one cat; caudal mandible, one cat; and maxilla, one cat. The healing periods varied from 6 to 9 weeks. In seven cases, implants were removed after a period of 3.5 to 18 months. In four cases the implants were left in place. The follow up period was between 8 and 36 months. In ten cases the procedure was successful, however in one case the outcome was not satisfactory due to a broken plate. There were no instances of dental malocclusion, nonunion, malunion, osteomyelitis or soft tissue infection. Eating, playing with toys, a fast transition to solid food and a quick return to normal jaw movements were observed. In our hands, the mini titanium plate fixation system was a safe and effective method for repairing certain maxillary and mandibular fractures in dogs and cats.     

Fracture healing after stabilization with intramedullary xenograft cortical bone pins: a study in pigeons

OBJECTIVE: To investigate the effectiveness of intramedullary xenograft cortical bone pins compared with stainless steel Kirschner wire for the repair of a standardized avian humeral fracture. STUDY DESIGN: Prospective randomized study. SAMPLE POPULATION: Thirty mature pigeons (Columba livia). METHODS: Birds were randomly assigned to 3 groups. Transverse mid-diaphyseal humeral fractures were created in 1 humerus in each bird. Fractures were stabilized with intramedullary ostrich or canine xenograft cortical bone pins or Kirschner wire. Radiographic, histological, and biomechanical assessments were used to compare fracture healing 6 weeks after fracture stabilization. The contralateral humerus of each bird was used as a control. RESULTS: All fractures healed regardless of intramedullary pin type. There were no statistically significant biomechanical differences among groups or within groups. Xenograft cortical bone pins induced a mononuclear inflammatory reaction that did not impair bone healing. Bones stabilized with intramedullary cortical bone pins had more periosteal callus and inflammation at the fracture site than bones stabilized with stainless steel Kirschner wires. CONCLUSIONS: Intramedullary xenograft cortical bone pins, derived from mammalian or avian sources, appear to represent an alternative for the repair of avian humeral fractures. CLINICAL RELEVANCE: Intramedullary xenograft cortical bone pins are biodegradable and may reduce the need for additional surgery to remove implants after fracture healing.     

Intramedullary pinning of metacarpal and metatarsal fractures in cats using a simple distraction technique

Objective— To describe a simple technique of intramedullary (IM) pinning for open reduction and internal fixation of metacarpal and metatarsal fractures in cats and evaluate outcome.
Study Design— Retrospective study.
Animals— Cats (n=17).
Methods— Medical records of cats with metacarpal and metatarsal fractures treated by a specific IM pinning method with Kirschner wires were reviewed. Types of fractures and number of pins used were recorded. Pre- and postoperative radiographs were evaluated. Outcome was assessed based on clinical examination, evaluation of radiographs, and owner questionnaire.
Results— Seventeen questionnaires were evaluated. Thirteen cats had a final recheck and radiographic assessment. Eight cats were lost to follow-up. Sixteen owners (94%) reported no obvious change in their cat's gait after treatment. One owner reported excellent function in her cat despite a slightly abnormal gait because of bent implants.
Conclusions— IM pinning after distraction of bone fragments is a reliable technique for treatment of metacarpal and metatarsal fractures in cats. Complications associated with fracture healing may or may not be associated with lameness.
Clinical Relevance— IM pinning used in conjunction with appropriate bandaging for 4 weeks yields excellent functional outcome for treatment of metacarpal and metatarsal fractures in cats. Metacarpo- and metatarsophalangeal joint damage is prevented using this technique.     

Radial and Tibial Fracture Repair with External Skeletal Fixation: Effects of Fracture Type, Reduction, and Complications on Healing

Twenty-eight consecutive fractures of the canine radius and tibia were treated with external skeletal fixation as the primary method of stabilization. The time of fixation removal (T1) and the time to unsupported weight-bearing (T2) were correlated with: (1) bone involved; (2) communication of the fracture with the external environment; (3) severity of the fracture; (4) proximity of the fracture to the nutrient artery; (5) method of reduction; (6) diaphyseal displacement after reduction; and (7) gap between cortical fragments after reduction. The Kruskal-Wallis one-way analysis of variance was used to test the correlation with p less than .05 set as the criterion for significance. The median T1 was 10 weeks and the median T2 was 11 weeks. None of the variables correlated significantly with either of the healing times; however, there was a strong trend toward longer healing times associated with open fractures and shorter healing times associated with closed reduction. Periosteal and endosteal callus uniting the fragments were observed radiographically in comminuted fractures, with primary bone union observed in six fractures in which anatomic reduction was achieved. Complications observed in the treatment of these fractures included: bone lysis around pins (27 fractures), pin track drainage (27 fractures), pin track hemorrhage (1 fracture), periosteal reaction around pins (27 fractures), radiographic signs consistent with osteomyelitis (12 fractures), degenerative joint disease (2 dogs), and nonunion (1 fracture). Valgus or rotational malalignment resulted in 16 malunions of fractures. One external fixation device was replaced and four loose pins were removed before the fractures healed. One dog was treated with antibiotics during the postoperative period because clinical signs of osteomyelitis appeared.(ABSTRACT TRUNCATED AT 250 WORDS)     

Internal fracture fixation

Over the past decade, many improvements to small animal internal fracture fixation have been developed, including improved fixation techniques and a more diverse selection of implants. The understanding that appropriate fixation selection is based on a plethora of biologic, mechanical, and clinical factors has also emerged. Classically, the methods of internal fracture fixation have used pins, wires, screws, and plates to rigidly stabilize fractures that have been anatomically reduced with significant disruption to the biologic fracture environment. Newer methods attempt to minimize trauma to the soft tissues surrounding a fracture and promote biologic osteosynthesis using such implants as interlocking nails and plate-rod fixations. This review provides an overview of both the traditional and current principles of small animal internal fracture fixation.     

Surgical salvage from comminuted metatarsal fracture using a weight-bearing pin-putty apparatus in a dog

Comminuted metatarsal fractures in a dog were treated using intramedullary pins externally connected and stabilized by epoxy resin putty and application of a fibreglass cast. Two weeks later the cast was removed. After further 2 weeks application of a Robert-Jones bandage the dog could stand and walk with the pin-putty apparatus in position. The pin-putty apparatus was removed 3 months postoperatively, and the dog resumed normal activity. This fixation method could be an easy, economical and effective alternative treatment for managing comminuted fractures of the metatarsal and possibly metacarpal bones in selected cases.     

Histological analysis of a central tarsal implant in a racing greyhound

The hock of a greyhound containing a titanium alloy central tarsal replacement was examined histologically. The animal had raced competitively 43 times before retirement. The examination showed that the adaptation and encapsulation of the implant by the surrounding bones, together with the excellent purchase of the screw into the fourth tarsal bone, had maintained the implant in excellent position during vigorous load-bearing. There was no histopathological evidence to suggest that the fixation of the implant was failing. The results provide evidence for the value of titanium alloy implants as a central tarsal replacement in greyhounds with type V fractures, and as a feasible alternative to euthanasia.     

Bilateral fixation of Y-T humeral condyle fractures via medial and lateral approaches in 29 dogs

OBJECTIVES: To describe bilateral fixation of Y-T fractures of the humeral condyle via combined medial and lateral approaches, and to determine the technique's clinical and radiographic short-term outcomes. METHODS: Details of 30 consecutive fractures in 29 dogs were reviewed. These included signalment, method of fixation, complications, and follow-up limb function and range of elbow joint motion. RESULTS: The age of the dogs ranged from three months to nine years, and bodyweight ranged from 1.9 to 48 kg. The humeral condyle was reattached to the shaft using medial and lateral bone plates in 18 fractures, a medial plate and lateral Kirschner wire(s) in six fractures, and medial and lateral Kirschner wire(s) in six fractures. Major complications were recorded in four fractures and minor complications in two fractures. Limb function at follow-up was graded as excellent in 12, good in 15 and fair in three fractures. The range of elbow flexion was normal in seven, mildly reduced in 18, moderately reduced in four and severely reduced in one fracture. CLINICAL SIGNIFICANCE: In contrast to the caudal approach, combined medial and lateral approaches decrease the extent of periarticular soft tissue dissection, avoid complications associated with olecranon osteotomy and enable exposure of the entire humeral diaphysis for fixation. Bilateral fixation is likely to be better at counteracting bending and torsional forces compared with unilateral fixation.     

Femur fractures associated with canine total hip replacement

OBJECTIVE: To report femur fracture as a complication of canine total hip replacement (THR) and to report the incidence, predisposing factors, treatment options, and outcome. STUDY DESIGN: Prospective clinical study. ANIMALS: Twenty-two client-owned dogs with 24 femoral fractures occurring during or after THR. METHODS: Cemented THR (BioMedtrix, Boonton, NJ) was performed. Medical records and radiographs were used to identify dogs that had femur fracture and to identify risk factors. Follow-up was obtained until dog death or study end. RESULTS: The overall incidence of femur fracture after THR was 2.9%. Femoral fractures occurred intraoperatively, immediately postoperatively, and up to 2196 days after THR. In 17 dogs, fractures resulted from a traumatic event. Osteopathy was present at THR in 5 dogs; all developed femoral fissures during reaming. Three dogs had fractures associated with cortical thinning secondary to aseptic loosening. Fracture treatment included euthanasia (1 dog), strict confinement (3 dogs), full cerclage wires on long oblique fractures (3 dogs), or plate and screw fixation (10 with, and 7 without, cerclage wires). All fractures extended near the distal tip of the femoral stem and all aggressively treated fractures healed. CONCLUSIONS: Predisposing risk factors for femur fracture after THR include osteopathy and iatrogenic fissures created during reaming. Trauma, excessive load concentration, and increased torque can lead to mid-diaphyseal fracture near the end of the femoral stem. Fracture did not disrupt THR implants. Cement fracture exposing the tip of the femoral stem did not affect fracture healing or rehabilitation. Immediate plate and screw fixation resulted in the most favorable outcome; healing occurred in 6-10 weeks. CLINICAL RELEVANCE: Femur fractures that occur after THR should be repaired using plate and screw fixation augmented with cerclage wire when needed. Forces on fissures should be neutralized to prevent propagation and fracture. Owners of high-risk patients (old dogs with osteopathies or previous hip surgery) should be counseled before THR. The prognosis is excellent when fractures are treated correctly.     

Use of external skeletal fixators in the repair of femoral fractures in cats

This paper reports the results of fixation of 35 femoral fractures in cats using an external skeletal fixator alone or in combination with supplementary devices. All the fractures healed. The average time to fixator removal was eight weeks and two days. The external skeletal fixator offers a method of repairing many types of femoral fractures in cats allowing sound orthopaedic principles to be maintained and producing a successful outcome.     

An expansion and compression technique for reducing and stabilizing proximal epiphyseal fractures of the tibia in foals.

Proximal tibial epiphyseal fractures in 2 foals were reduced and stabilized by expansion and compression between 2 transversely placed Steinman pins, one on each side of the fracture. A Charnley apparatus or turnbuckles placed between the pins on each side of the fracture provided the mechanical advantage for repositioning the fracture fragments and achieving rigid fixation during healing. A light cast was applied over the fixation apparatus, keeping the limb in an extended position. The cast and fixation apparatus were removed after 4 weeks. The technique allowed rapid healing and adequate ambulation. The foals had functional, straight hindlimbs 6 months after the fractures occurred.     

Crosspin Fixation of Fractures of the Proximal Tibia in Three Foals

Three foals, each less than 1 month of age, were presented with Salter Type II fractures of the proximal tibial physis. Reduction of the fractures was accomplished manually and maintained by crosspin fixation. Fracture healing in two of the foals was uncomplicated. The third foal developed an infection around the implants, which responded to periodic local antiseptic flushing and administration of penicillin and gentamicin. Follow-up information ranging from 11 to 22 months after surgery revealed satisfactory results in two of three foals; premature closure of the proximal tibial physis was found in the other foal, resulting in the development of an angular limb deformity.