Long-term outcomes of atrophic/oligotrophic non-unions in dogs and cats treated with autologous iliac corticocancellous bone graft and circular external skeletal fixation: 19 cases (2014-2021).

OBJECTIVES: To determine the short- and long-term outcomes and complications in dogs and cats undergoing surgical treatment for viable oligotrophic and nonviable atrophic non-unions using circular external skeletal fixation and autologous corticocancellous bone graft. MATERIALS AND METHODS: In this case series, the medical records and radiographs of all dogs and cats with radius/ulna and tibia/fibula viable oligotrophic and nonviable atrophic non-unions treated with corticocancellous bone graft and circular external skeletal fixation at two referral veterinary hospitals between 2014 and 2021 were retrospectively reviewed. The long-term follow-up was 1 year or greater. RESULTS: Thirteen dogs and six cats with 19 non-union fractures met the inclusion criteria for the study. Eighteen non-union fractures (94.7%) healed and one did not. Five patients (26%) had minor perioperative period complications (<3 months). The patient that did not achieve bone union underwent revision surgery with internal fixation (plate and screws) and autologous cancellous bone graft. Fifteen (78.9%) cases returned to full function and three (15.8%) cases returned to acceptable function in the long-term follow-up period. CLINICAL SIGNIFICANCE: The use of circular external skeletal fixation associated with autologous corticocancellous bone graft for the treatment of radius/ulna and tibia/fibula atrophic/oligotrophic non-union fractures in dogs and cats was considered successful in the majority of patients and was free of major or catastrophic complications.

Long-Term Assessment of Bone Regeneration in Nonunion Fractures Treated with Compression-Resistant Matrix and Recombinant Human Bone Morphogenetic Protein-2 in Dogs.

OBJECTIVE: The aim of this study was to assess bone density, bone architecture and clinical function of canine nonunion distal appendicular long bone fractures with a defect treated with fixation, compression-resistant matrix and recombinant human bone morphogenetic protein-2 (rhBMP-2). STUDY DESIGN: Prospective cohort study with dogs at least 1-year post treatment. Computed tomography was performed and quantitative measurements from previous fracture sites were compared with measurements from contralateral limbs. Subjective evaluation included gait assessment and palpation. RESULTS: Six patients met the inclusion criteria. The rhBMP-2 treated bone exhibited higher density at the periphery and lower density in the centre, similar to the contralateral limb. All patients were weight bearing on the treated limb and all fractures were healed. CONCLUSION: The rhBMP-2-treated bone underwent restoration of normal architecture and density. Acceptable limb function was present in all patients. The results of this study can serve as a basis for long-term response in treating nonunion fractures in veterinary patients.

Canine Elbow Dysplasia: Ununited Anconeal Process, Osteochondritis Dissecans, and Medial Coronoid Process Disease.

Elbow dysplasia is a major cause of front limb lameness in medium to large dog breeds. Underlying causes include ununited anconeal process, medial coronoid process disease, and osteochondritis dissecans. When a definitive diagnosis of elbow dysplasia is made, the surgeon can improve elbow function but cannot entirely prevent progression of osteoarthrosis. Conventional surgical treatment with joint debridement and removal of loose osteocartilaginous bodies is not rewarding if joint incongruity persists; the result is overloading and subchondral bone exposure with erosion of the cartilage of the medial humeral condyle and medial coronoid area of the ulna leading to medial compartment disease.

Clinical Efficacy of Bone Reconstruction Surgery with Frozen Cortical Bone Allografts for Nonunion of Radial and Ulnar Fractures in Toy Breed Dogs.

OBJECTIVE: To evaluate the effectiveness of frozen cortical bone allografts (FCBA) in the treatment of severe radial and ulnar atrophic nonunion fractures. ANIMALS: Toy breed dogs with nonunion of radial and ulnar fractures (n = 15). METHODS: Severe atrophic nonunion fractures were treated with FCBA (eight infected and seven non-infected fractures). Radiographs obtained immediately after surgery, and 1, 2, 3, 6 and 12 months later were evaluated and scored for the periosteal reaction at the bone regeneration sites, the healing process in the bone connection areas at both the proximal and distal sites, and the bone remodelling process within the allografts. RESULTS: Improvements in the fracture-healing process and weight-bearing function were observed in all cases. Radiographic scores at the bone connection areas and within the allograft improved significantly over time (p < 0.05). There were not any significant differences in radiographic scores between the infected and non-infected groups. CLINICAL SIGNIFICANCE: Bone reconstruction with FCBA is effective in the treatment of radial and ulnar nonunion fractures associated with large bone defects, regardless of the infection status of the surgical site.

Use of stem-cell sheets expressing bone morphogenetic protein-7 in the management of a nonunion radial fracture in a Toy Poodle.

A 12-year-old castrated Toy Poodle was referred to the Kangwon National University Animal Hospital with an oligotrophic nonunion fracture in the distal 1/3 of the left radius and an intact ulna. After fixation by a locking plate and screws, adipose-derived mesenchymal stem-cell sheets expressing bone morphogenetic protein 7 (BMP-7) were transplanted to the fracture site to enhance the healing activity. The fracture was healed at 9 weeks after surgery. In the present case, the mesenchymal stem-cell sheets expressing BMP-7 promoted bone regeneration and healing in a nonunion fracture.

Outcome of nonunion fractures in dogs treated with fixation, compression resistant matrix, and recombinant human bone morphogenetic protein-2.

OBJECTIVES: To report the use of compression resistant matrix (CRM) infused with recombinant human bone morphogenetic protein (rhBMP-2) prospectively in the healing of nonunion long-bone fractures in dogs. METHODS: A longitudinal cohort of dogs that were presented with nonunion fractures were classified and treated with CRM soaked with rhBMP-2 and fracture fixation. They were followed with serial radiographs and evaluated for healing times and complications according to the time frame and definitions previously established for orthopaedic clinical cases. RESULTS: Eleven nonunion fractures in nine dogs were included. Median healing time was 10 weeks (range: 7-20 weeks). Major perioperative complications due to bandage morbidity were encountered in two of 11 limbs and resolved. All other complications were minor. They occurred perioperatively in eight of 11 limbs. Minor follow-up complications included short-term in one of two limbs, mid-term in one of three, and long-term in four of five limbs. Nine limbs returned to full function and two limbs returned to acceptable function at the last follow-up. CLINICAL SIGNIFICANCE: Nonunion fractures given a poor prognosis via standard-of-care treatment were successfully repaired using CRM with rhBMP-2 accompanying fixation. These dogs, previously at high risk of failure, returned to full or acceptable function.

Bovine xenograft application for treatment of a metatarsal nonunion fracture in an alpaca (Vicugna pacos).

CASE HISTORY: A 15-year-old female huacaya alpaca (Vicugna pacos) was referred because of a non-weight-bearing lameness (4/4) in the left pelvic limb caused by a grade three open metatarsal fracture. The referring veterinarian treated the fracture with conservative management using bandages, but it progressively evolved to a non-union. CLINICAL FINDINGS AND DIAGNOSIS: Clinical examination revealed external wounds on the medial and lateral surfaces of the metatarsus. Radiographs confirmed an open, nonarticular, displaced, diaphyseal fracture of the left metatarsus. TREATMENT AND OUTCOME: Cancellous bone was sourced from bovine proximal and distal femur epiphyses, followed by a thermal shock procedure to achieve decellularisation, to produce a xenograft. Open reduction and internal fixation of the fracture using locking plates was performed. Alignment of the fracture fragments was corrected and the xenograft was placed at the debrided fracture site to stimulate and harness osteogenesis in situ. Clinical and radiographic follow-up was performed up to 40 weeks postoperatively. Clinical evaluations revealed that the alpaca gradually increased weight bearing following bandage removal 10 days after surgery. Serial radiographs showed correct alignment of the left metatarsus, progressive bone modelling and, complete bone union at 12 weeks. Ten months postoperatively the alpaca showed no signs of lameness and resumed normal activity. CLINICAL RELEVANCE: For management of a metatarsal non-union, a combination of bovine xenograft application and angular stable internal fixation progressed toward an excellent long-term recovery.

Regenerating Mandibular Bone Using rhBMP--2: Part 2-Treatment of Chronic, Defect Non-Union Fractures.

OBJECTIVE: To describe a surgical technique using a regenerative approach and internal fixation for reconstruction of critical size bone defect non-union mandibular fractures. STUDY DESIGN: Case series. ANIMALS: Dogs (n = 6) that had internal fixation of defect non-union mandibular fracture. METHODS: In 5 dogs, the repair was staged and extraction of teeth performed during the initial procedure. After 21-98 days (mean, 27 days) pharyngotomy intubation and temporary maxillomandibular fixation were performed. Using an extraoral approach, a locking titanium miniplate was contoured and secured to the mandible. A compression resistant matrix (CRM) infused with rhBMP-2 was implanted in the defect. The implant was then covered with a soft tissue envelope followed by surgical wound closure. RESULTS: All dogs healed with intact gingival covering over the mandibular fracture site defect and had immediate return to normal function and correct occlusion. Hard-tissue formation was observed clinically within 2 weeks and solid cortical bone formation within 3 months. CT findings in 1 dog at 3 months postoperatively demonstrated that the newly regenerated mandibular bone had 92% of the bone density and porosity compared to the contralateral side. Long-term follow-up revealed excellent outcome. CONCLUSION: Mandibular reconstruction using internal fixation and CRM infused with rhBMP-2 is an excellent solution for the treatment of critical size defect non-union fractures in dogs.

Treatment of antebrachial and crural septic nonunion fractures in dogs using circular external skeletal fixation: a retrospective study.

OBJECTIVE: To evaluate the outcome of treatment of antebrachial and crural septic non-union fractures in dogs using circular external skeletal fixation (CESF), and to document the type and frequency of complications associated with this technique. METHODS: The medical records of all dogs with infected antebrachial and crural non-union fractures treated using the methods of Ilizarov at the Department of Animal Pathology of the University of Turin between 2006 and 2011 were retrospectively reviewed. Only dogs in which radiographic and clinical assessment were available at the time of CESF removal were included in the study. RESULTS: Twenty-three dogs met the inclusion criteria. Twenty nonunion fractures treated with CESF healed and three did not. The latter three cases underwent amputation of the affected limb. In the 20 dogs that achieved bone union, six had minor complications and five had major complications. The mid-term outcome was judged to be excellent (n = 11), good (n = 6), fair (n = 2), or poor (n = 4). CONCLUSIONS: The results of this study support the use of CESF for the management of antebrachial and crural septic nonunion fractures in dogs. Union was achieved in the majority of dogs and the complication rate was acceptable, considering the severity of the nonunion fractures that were managed in this fashion.

Total knee replacement in a dog with a non-union type B3 tibial plateau fracture.

A six-year-old German Shorthaired Pointer was presented with a 12 month history of left pelvic limb lameness following trauma. Clinical examination revealed marked thickening and reduced range-of-motion of the left stifle and radiographs were suggestive of a non-union type B3 tibial plateau fracture with severe secondary osteoarthritis. Total knee replacement was performed with adjunctive stabilization of the proximal tibial fracture fragment. Clinical follow-up at six and 12 months with quantitative gait analysis revealed significant improvement in limb function.

Clinical efficacy of autogenous cancellous bone and fibroblast growth factor 2 combined with frozen allografts in femoral nonunion fractures.

OBJECTIVES: To evaluate the efficacy of cortical allograft and fibroblast growth factor 2 (FGF-2)-impregnated autogenous cancellous bone in nonunion fracture repair in dogs. METHODS: From January 2000 to August 2010, seven dogs underwent cortical allograft and FGF-2-impregnated autogenous cancellous bone implantation for treatment of a femoral nonunion following fracture. Radiographic images were used to assess healing. RESULTS: The average length of the implanted cortical allograft was 29.1 ± 4.4 mm. A significant improvement in the postoperative percentage of femoral shortening was observed with the experimental treatment, from 85.2 ± 8.2% to 95.0 ± 4.8%. Using radiographic scoring, we analysed the process of bone remodelling. At three months post-surgery, the proximal and distal fracture lines had begun to disappear, and a complete absence was observed after six months. Bacterial infection was detected in two of the seven cases. CLINICAL SIGNIFICANCE: The findings of our study suggest that the combination of cortical allografts with FGF-2 impregnated cancellous autograft may be useful in cases of diaphyseal fracture non-union. The disappearance of the fracture line in dogs with nonunion was recognized at the same phase as the report in which healing process of allograft was evaluated in the experimental ostectomy model using the normal dog.

Defect nonunion of a metatarsal bone fracture in a cow: successful management with bone plating and autogenous cancellous bone graft.

A two-and-half-year-old cow was presented with a defect nonunion of the right metatarsal III/IV bone following a severely comminuted open fracture two months previously. The animal underwent open fixation using a 4.5 mm, broad, 10-hole, dynamic compression plate and autogenous cancellous bone graft collected from the contralateral iliac shaft. The animal started partial weight bearing after the third postoperative day and resumed complete weight bearing after the 10th day. Fracture healing was complete and the implants were removed after the 120th postoperative day. Stable fixation by means of a bone plate in conjunction with a cancellous bone graft facilitated complete healing and restoration of the bone column of the defect and the metatarsal fracture. The animal made a complete recovery.

Complications associated with cheek tooth extraction in the horse.

Common indications for cheek tooth extraction in the horse include dental fracture, periodontal disease, severe decay/ caries, mandibular fracture with alveolar/tooth involvement, and periapical abscess. Complications secondary to extraction of cheek teeth are prevalent. Typical complications may include retained root tip(s), collateral damage of neighboring teeth and alveolar bone, mandibular fracture non-union or delayed union, cemental ankylosis, dilacerated root(s), oroantral/oronasal fistula, palatal deviation of cheek teeth, bone sequestration, sinus involvement, alveolar plug failure, and palatine artery laceration. This paper presents a series of cases that had complications following cheek tooth extraction. Anticipation of problematic extractions, recognition of complications, and appropriate treatment will aid the clinician in managing the inevitable cheek tooth extraction complication.

Osteoprogenitor cell therapy in an equine fracture model.

OBJECTIVE: To compare the efficacy of osteoprogenitors in fibrin glue to fibrin glue alone in bone healing of surgically induced ostectomies of the fourth metacarpal bones in an equine model. STUDY DESIGN: Experimental. ANIMALS: Adult horses (n = 10). METHODS: Segmental ostectomies of the 4th metacarpal bone (MC4) were performed bilaterally in 10 horses. There was 1 treatment and 1 control limb in each horse. Bone defects were randomly injected with either fibrin glue and osteoprogenitor cells or fibrin glue alone. Radiography was performed every week until the study endpoint at 12 weeks. After euthanasia, bone healing was evaluated using radiography and histology. Analysis of radiographic data was conducted using a linear-mixed model. Analysis of histologic data was conducted using a general linear model. Statistical significance was set at P < .05. RESULTS: Radiographic grayscale data as a measure of bone healing revealed no significant difference between treatment and control limbs. Radiographic scoring results also showed that the treatment effect was not significant. Histologic analysis was consistent with radiographic analysis showing no significant difference between the area of bone present in treatment and control limbs. CONCLUSION: Injection of periosteal-derived osteoprogenitors in a fibrin glue carrier into surgically created ostectomies of MC4 does not accelerate bone healing when compared with fibrin glue alone.

Effects of a novel hydrogel on equine bone healing: a pilot study.

OBJECTIVE: To examine the efficacy and biocompatibility of a thiolated gelatin-thiolated carboxymethyl hyaluronan (CMHA-SGX) sponge as an osteoconductive device in an equine second and fourth metacarpal bone defect model. METHODS: Seven millimetre segmental ostectomies were created bilaterally in the second and fourth metacarpal bones of four horses. The left and right metacarpal defects were randomly assigned to (1) be filled with a CMHA-SGX sponge (treated) or (2) were left unfilled (control). The duration of the study was nine weeks. Bone healing was evaluated using serial radiology, as well as histologically and histomorphometrically. Data were analyzed using an analysis of variance (ANOVA). The level of significance was p<0.05. RESULTS: Serial radiographic evaluation revealed improved healing in the treated compared to the control defects at weeks eight and nine (p = 0.02). This finding was not corroborated histologically. Histomorphometry did not reveal any significant differences in healing between experimental groups. The CMHA-SGX sponge did not inhibit bone formation, induce local inflammation or lead to surgical site infection. CLINICAL SIGNIFICANCE: While further optimization to improve osteoconductive properties should be considered, the CMHA-SGX sponge appears to be a biocompatible orthopaedic implant and its use as a carrier for osteogenic proteins warrants further investigation.

Clinical application of recombinant human bone morphogenetic protein in cats and dogs: a review of 13 cases.

Databases (2001-2008) for cases in which recombinant bone morphogenetic protein (rhBMP) was used to aid in management of orthopedic disease were reviewed and cases were categorized as non-unions, delayed unions, and cases expected to heal with difficulty. If follow-up in the medical record was < 6 mo for live animals, owners were surveyed by telephone. Thirteen cases (11 dogs, 2 cats) were identified; OP-1 (rhBMP-7) was used in 3 cases and INFUSE (rhBMP-2) in 10. Mean time from injury to rhBMP use for non- and delayed union cases was 156 d; mean time from rhBMP use to radiographic healing was 101 d. No systemic side effects were reported. All patients achieved clinical and radiographic bone union following rhBMP administration. Recombinant human BMP was used in 13 veterinary patients to successfully achieve bone union without serious deleterious effects in a variety of clinical applications.

Treatment of a nonunion, secondary to gunshot fracture, of the distal radius with circular external fixation and rhBMP-2 in a cat.

OBJECTIVE: To report the successful use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in the treatment of an antebrachial non-union, secondary to gunshot fracture, stabilized with circular external fixation in a cat. PROCEDURE: Following a diagnosis of a highly comminuted gunshot fracture of the distal right radius and ulna, the fracture was stabilized with a circular external fixation. A two-ring frame was placed in closed fashion. RESULTS: The skin wound healed uneventfully by second intention in 21 days. Twenty-eight weeks after external fixation, bone healing was absent. 0.8mL of 0.2mg/mL of rhBMP-2 in two collagen sponges was placed in the bone defect. Eight weeks after rhBMP-2 implantation, an early bone healing response was noted on radiographic evaluation. Sixteen weeks after rhBMP-2 implantation, fracture union was achieved. DISCUSSION: To the authors' knowledge, 160 µg is the lowest reported dose of rhBMP-2 that leads to bony union in a cat. However as an individual case study, this report can not be used as evidence that rhBMP-2 at this lower dose is appropriate for use in all cats. Further studies are needed to establish the minimum efficient dose of rhBMP-2 in cats.

Transverse stress fractures of the proximal tibia in 10 cats with non-union patellar fractures.

Ten cats with a mean age of eight years and five months had suffered proximal transverse tibial fractures; in four of them both tibiae had fractured at different times. All the cats also had bilateral non-union patellar fractures, and nine of them had evidence of fractures elsewhere, including acetabular, ischial, humeral condylar and rib fractures, which had occurred before or after the tibial fractures. All the tibial fractures were proximal and transverse. Radiographically, there was thickening and sclerosis of the cranial cortex adjacent to and at the level of the fracture, changes that were compatible with stress fractures. The outcome of repair of the tibial fracture was known in nine of the cats; eight of them healed and one resulted in a non-union. Two of the cats were euthanased as a direct result of the fracture or complications with the repair.

Evaluation of nonunion fractures in dogs by use of B-mode ultrasonography, power Doppler ultrasonography, radiography, and histologic examination.

OBJECTIVE: To investigate the use of ultrasonography to assess nonunion of fractures in dogs and to compare results of ultrasonography, radiography, and histologic examination. SAMPLE POPULATION: 8 nonunion fractures in 6 dogs (1 each in 5 dogs and 3 in 1 dog); dogs ranged from 7 to 94 months of age and weighed 6 to 30 kg. PROCEDURES: Diagnostic assessment consisted of complete clinical and orthopedic examinations, radiography, B-mode (brightness mode) ultrasonography, and power Doppler ultrasonography. Biopsy samples were obtained during surgery for histologic examination. They were stained with H&E and immunolabeled by use of anti-CD31 antibodies. Correlations of power Doppler score, power Doppler count, vessel area, and radiographic prediction with the mean number of vessels counted per hpf were derived. RESULTS: Radiographically, 7 of 8 nonunion fractures were diagnosed as atrophic and were therefore estimated to be nonviable. Vascularity of nonunion fractures during power Doppler ultrasonography ranged from nonvascularized to highly vascularized. Absolute vessel count during histologic examination ranged from 0 to 63 vessels/hpf; 5 nonunion sites had a mean count of > 10 vessels/hpf. Vascularity during power Doppler ultrasonography was highly correlated with the number of vessels per hpf, whereas the correlation between the radiographic assessment and histologic evaluation was low. CONCLUSIONS AND CLINICAL RELEVANCE: Radiographic prediction of the viability of nonunion fractures underestimated the histologically assessed vascularity of the tissue. Power Doppler ultrasonography provided a more accurate estimation of the viability of the tissue and therefore the necessity for debridement and autografts during revision surgery.