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.     

Composite fixation of comminuted ilial wing fractures in cats: three cases

CLINICAL SUMMARY: The surgical repair of comminuted ilial wing fractures (comprising a long oblique fracture with ventral multiple fragmentation) in three cats using composite internal fixation is reported. The technique comprised the use of pins, screws, wire and polymethylmethacrylate. All cases had an excellent outcome with uneventful bone healing. One case had a very mild reduction in pelvic canal diameter postoperatively. There was no evidence of implant loosening or migration in any cat on follow-up radiographs. PRACTICAL RELEVANCE: This technique provided a quick and highly adaptable means of stabilising this fracture configuration, as well as restoring pelvic symmetry, when limited buttressing support and bone stock were available cranial and ventral to the acetabulum. This method of fixation may have biomechanical advantages over lateral or dorsal plating techniques for this particular type of fracture configuration.     

A REVIEW OF THE EFFECTS OF RADIATION THERAPY ON BONE

A literature review describes bone changes that may develop after radiation therapy. Irradiation of mature bone results in vascular and cellular changes best characterized as osteopenia. Irradiated bone is susceptible to subsequent fracture, septic osteoradionecrosis, and sarcoma formation. Irradiation of fractured bones may result in delayed healing or nonunion of the fracture; however, in some patients, healing will occur. Pathologic fractures associated with neoplasia may heal after radiation therapy if internal fixation is employed. Irradiation of growing bone typically results in retardation of longitudinal growth. Clinical manifestations of radiation-induced changes of bone are uncommon; however, when they occur, the results may be devastating.     

Principles of long bone fracture management.

The fixation of fractures in which one of the following primary devices is used: IM pins, bone plates, external skeletal fixators, can benefit from the additional application of any number of secondary devices. The secondary devices include cerclage, hemicerclage, or interfragmentary wires, skewer-pins, screws, and external skeletal fixators. These are indicated to facilitate the repair and eliminate the forces acting on the fracture site. A complete understanding of all the methods of fixation facilitates the selection of the proper implant or combination of implants. This information must be combined with the knowledge of how each device is most appropriately used depending on both the fracture type and fracture location. Taking into consideration all of these factors helps ensure that fracture healing occurs in the shortest possible time with the fewest complications. The ultimate goal of obtaining a full return to function may thereby be achieved.     

Clinical considerations of the thoracic limb.

The avian skeleton is significantly different from the mammalian skeleton, and these differences are important when providing fracture repair and postoperative care for the avian patient. Successful repair depends on an understanding of fracture management and healing and of the anatomical, physiologic, and behavioral concerns of avian patients. Having knowledge of fracture repair without an understanding of the unique needs of avian patients' results in a disappointing treatment response.     

Can bone marrow aspirate improve mandibular fracture repair in camels (Camelus dromedarius)? A preliminary study

BackgroundMandibular fractures are common in camels, leading to considerable economic losses. This study explored methods of improving mandibular fractures repair, adjuvant with interdental wire, or bone plate fixation. Autologous bone marrow (BM) injection enhances osteogenesis and rapid healing.ObjectivesTo investigate the effect of autologous BM aspirate as an adjuvant treatment for repairing mandibular fractures in camels with interdental wire, or bone plate fixation.MethodsThirty dromedary camels aged 5–8 years and of both sexes were randomly divided into 4 treatment groups: group 1 (n = 10) treated with stainless steel wire fixation and BM injection at the fracture line, group 2 (n = 10) treated with plate fixation and BM injection at the fracture line, group 3 (n = 5) treated with stainless steel bone wire fixation and placebo saline injection at the fracture line, and group 4 (n = 5) treated with plate fixation and placebo injection at the fracture line. The mandibular fractures were followed weekly for 12 weeks postoperatively to assess improvement and healing based on clinical evaluation, radiographic union scale, and bone turnover markers (i.e., bone alkaline phosphatase, osteocalcin, pyridinoline, and deoxypyridinoline).ResultsCompared to other groups, elevated bone turnover markers in group 1 were demonstrated (p < 0.05) on the seventh postoperative day. Likewise, compared to other groups, both clinical findings and radiographic union scale significantly improved (p < 0.05) in group 1 on the 56th postoperative day.ConclusionsBM aspirate has a promising beneficial osteogenic effect on mandibular fracture repair in camels, most notably when combined with interdental wire fixation.     

Fractures of the radius and ulna.

Fractures of the radius and ulna are common in the dog and cat. If treated inappropriately, complications may result. These include delayed union, nonunion, malunion, and growth deformities. ESF is a versatile method of fixation for fractures of the radius and ulna. Types that are applicable range from the simple type I to the complex type III fixator. In general, the more unstable the fracture, the more rigid the assembly must be to counteract fracture forces. There are three basic phases to consider when using ESF: (1) preoperative planning, (2) application of the ESF, and (3) long-term management. A deficiency in any one of these phases can lead to complications and an unsatisfactory clinical outcome. Although ESF can be used on many types of fractures, the technique is especially well suited for open or highly comminuted fractures when internal fixation is not applicable. In these cases, close attention must be paid to the integrity of the soft tissues. In addition, cancellous bone grafts should be placed either at the time of initial repair or in a delayed fashion after adequate vascularity has been established. Staged or complete removal of the ESF should be individualized to each fracture case. In general, staged disassembly or "dynamization" can begin when the bone and fixator begin to function as a composite as determined by radiographs. Complete fixator removal should be considered when the fracture exhibits clinical and radiographic evidences of union.     

Distal tibial fractures in dogs and cats

A total of 43 fractures of the distal tibia in dogs and cats were evaluated for fracture patterns, methods of stabilization, and time to bone union. Fractures of the metaphysis (9.3%), physis (30.9%), epiphysis (2.3%), and malleoli (58.2%) were classified. Open reduction and internal fixation, with combinations of Kirschner wire, orthopedic wire, and bone screws, were the methods of fixation used in the majority of fractures. These relatively simple methods of fixation were applied to all sizes of dogs and cats and resulted in an average bone healing time of 6 weeks.     

Short incomplete sagittal fractures of the proximal phalanx in ten horses not used for racing

Objective— To describe short incomplete sagittal fractures of the proximal phalanx (type Ia P1 fractures) in horses not used for racing and report outcome.
Study Design— Retrospective study.
Animals— Horses (n=10) with type Ia P1 fractures.
Methods— Retrieved data of horses with type Ia P1 fractures were signalment, history and results of orthopedic examination. Radiographs were re-evaluated for position and length of the fracture line, presence of osteoarthritis or subchondral cystic lesions (SCL), periosteal new bone formation and subchondral sclerosis. Conservative treatment (n=4) included box confinement for 2 months followed by 1 month of hand walking. Surgical therapy (n=6) consisted of internal fixation by screws inserted in lag fashion in 5 horses. Concurrent SCL were debrided by curettage via a transcortical drilling approach. In 1 horse, only SCL curettage but not internal fixation was performed. Outcome was assessed on a clinical and radiographic follow-up examination in all horses.
Results— Mean follow-up time was 27 months (median, 13.5 months; range, 9 months to 9 years). All horses treated with internal fixation were sound at follow-up and had radiographic fracture healing. Of the 4 horses managed conservatively, 3 remained lame and only 1 horse had radiographic evidence of fracture healing. Catastrophic fracture propagation occurred in 2 horses not treated by internal fixation, 20 and 30 months after diagnosis, respectively.
Conclusions— Horses with a type Ia P1 fracture treated surgically had a better outcome than those managed conservatively and lack of fracture healing seemingly increases the risk of later catastrophic fracture.
Clinical Relevance— Surgical repair of type Ia P1 fractures should be considered to optimize healing and return to athletic use.     

Deep-Frozen Allogeneic Cancellous Bone Grafts in 10 Dogs: A Case Series

Deep-frozen, aseptically collected and processed allogeneic cancellous bone was implanted in eight dogs during the surgical repair of diaphyseal long bone fractures and in two dogs during arthrodeses. A combined allogeneic and autogeneic cancellous bone graft was used in two fractures with a segmental bone loss of more than 5 cm. Bone union occurred in five fractures and in both arthrodeses. Failure of fixation occurred in two dogs with nonunion fractures and in a third dog with an open, infected fracture. Biopsies from the fracture sites were obtained from these dogs following failure of their fracture fixation. The cancellous bone graft appeared to be in the process of normal incorporation in each case. Failure of fixation was attributed to technical or case management errors or both, in each of the three fractures that failed to achieve bony union. Frozen allogeneic cancellous bone grafts were effectively incorporated when used in the primary repair of fractures and arthrodeses. Combined autogenous and allogeneic cancellous bone grafts may be particularly useful in the repair of fractures with large segmental diaphyseal bone defects. The use of allogeneic cancellous bone grafts in nonunion fractures requires further investigation before it can be recommended.     

Complications of fractures repaired with plates and screws

The complications associated with bone plates and screws often are related to undersized or oversized implant selection, improper number of implants, inadequate or improper screw fixation, malpositioned plates or screws, poor plate contouring, and failure to use cancellous bone grafts when a gap is present at the fracture site. A thorough understanding of the principles of plate and screw application helps to avoid most problems. The surgeon must use an implant that will stabilize the fracture adequately during the healing process. The patient's activity levels must not exceed the mechanical limits of the implant. Methods to promote bone healing, such as using cancellous bone grafts when a deficit is present, help to protect the implant from fatiguing before the fracture is healed. Proper positioning and contouring of the implants are important to the successful application of plates and screws. It must be realized that even if all of these things are done, some complications still will occur. When that happens, the complication should be dealt within a manner that will allow the objectives of fracture treatment (a healed bone and normal limb function) to be achieved.     

Racing prognosis of horses following surgically repaired olecranon fractures

Olecranon fracture is a common orthopedic problem in juvenile horses. Prognosis for complete fracture healing when various methods of internal fixation are used is good; however, the impact of olecranon fracture stabilization on the likelihood that foals will start on a racecourse is unknown. Medical records of foals undergoing internal fixation for an olecranon fracture were reviewed. The dam's foaling records were obtained and lifetime racing records were then retrieved for both the affected foals and 1 of their siblings. Twenty-two of 24 repaired fractures healed completely, subsequently, 16 of the foals started in at least 1 race. Statistical calculations suggest that when compared with their siblings, the occurrence of olecranon factures requiring internal fixation in juvenile racehorses will not significantly reduce the likelihood that they will race; however, the siblings had significantly more lifetime race starts and higher career earnings.     

Principles and application of internal fixation in cattle

The principles of bone healing and vascular and periosteal responses are considered in relation to different methods of fracture fixation and complications. Advantages and disadvantages of the available internal fixation devices are reviewed for the fractures that most commonly occur in the different age groups.     

Femoral Head and Neck Fractures in the Dog and Cat: A Review of 115 Cases

Case histories of 115 dogs and cats with fractures of the femoral head or neck, were reviewed; these animals had been presented to the Ohio State University Veterinary Hospital between 1969 and 1976. Signalment, fracture type by anatomic location, fracture to fixation interval, surgical approaches used, methods of surgical repair, surgical complications, and final results of surgical repair were examined. Avascular necrosis of the femoral head was not a clinically significant problem following internal fixation in this study. Most animals had very good to excellent limb function following fracture repair.     

Principles of conservative fracture management: splints and casts

Splint and cast application is an often overlooked form of fracture management in the current era of internal fixation and external skeletal fixation. External limb splintage is a "tried and true" method; however, there are specific indications for the use of this technique. Splints and casts have a place in our armamentarium of fracture management and when appropriately used under the correct circumstances, fracture healing is expected to be similar to that observed using other means of fracture fixation.     

T-plate repair of fracture of the nasal bones in a horse.

A 5-hole T-plate was used to repair an unstable compound depression fracture of the nasal bones in a horse. Substantial bone loss was evident as a result of severe trauma. Satisfactory bone healing, facial contour, and airway function were achieved. The use of a T-plate can be an alternative means of repair of a nasal bone fracture in a situation in which instability and/or bone loss exists.     

Complications after orthopedic surgery in alpacas and llamas: 24 cases (2000-2006)

Objective— To report complications associated with orthopedic surgery in alpacas and llamas.
Study Design— Retrospective study.
Animals— Alpacas (n=18) and llamas (n=6) that orthopedic surgery using internal or external fixation.
Methods— Medical records (January 2000–December 2006) and radiographs were reviewed and owners contacted for follow-up information for alpacas and llamas that had orthopedic surgery involving internal or external fixation. Fourteen camelids had internal fixation, 7 had external fixation, and 3 had a combination of internal and external fixation.
Results— Twenty-two animals (92%) were discharged after surgery (mean hospitalization, 15 days). Of 20 animals with ≥1 year follow-up information, 18 were alive (82%). Postoperative complications related to fracture healing, infection, soft tissue structures, or joints occurred in 21 camelids (87%). Thirteen animals returned to their intended use, 4 animals returned to breeding but not their intended use, 4 were euthanatized, and 3 were only able to be used as pets.
Conclusions— Fixation type (internal, external) did not have any significant effect on complications involving fracture healing, infection, soft tissue structures, or chronic lameness. Camelids with open fractures were more likely to have complications associated with fracture healing, repair, and infection than closed fractures.
Clinical Relevance— Complications after orthopedic surgery in alpacas and llamas are more common than previously reported and may result in chronic lameness or prevent return to their intended use.     

Bone grafts.

Bone grafting provides a method of enhancing bone healing in veterinary orthopedic patients. Specifically, autogenous cancellous bone graft provides the cellular components and matrix proteins that can accelerate bone healing, dramatically. Allografts provide immediate mechanical support for fracture repair and patient function, but these grafts do not create the osteogenic environment seen with the use of autogenous cancellous bone graft. Xenograft bone implants may also hold a place for use in fracture management. With the advent of recombinant bone-derived tissue growth factor technology, bone grafting may some day become a practiced technique of the past. For now, however, bone grafting still holds a strong place in orthopedic surgery when dealing with bone defects in animals.     

Clinical Use of Recombinant Human Bone Morphogenic Protein-2 in a Whooping Crane (Grus americana)

Objective— To report use of recombinant human bone morphogenetic protein-2 (rhBMP-2) as adjunctive therapy for treatment of a comminuted, open, proximal humeral fracture in an avian species.
Study Design— Clinical report.
Animals— A 3.5-month-old male whooping crane ( Grus americana ).
Methods— An open, severely comminuted humeral facture was stabilized with an intramuscular (IM) pin/type IA external skeletal fixator with tie-in configuration. rhBMP-2 was applied in a calcium phosphate matrix (CPM) paste directly to the fracture site as a bone graft substitute. Radiographic evidence of bone healing was monitored for 14 weeks.
Results— Substantial bony callus was evident at 4 weeks and at 8 weeks there was bridging callus with obvious bony remodeling. The fixation was destabilized at 9 weeks by IM pin removal, bone healing progressed and the fixator was removed at 11 weeks. By 14 weeks both cortices had been re-established with continued callus remodeling evident.
Conclusion— rhBMP-2, applied in a CPM paste, was used as a bone graft substitute in the treatment of a comminuted, open humeral fracture in a whooping crane.
Clinical Relevance— Use of rhBMP-2/CPM should be considered in treatment of avian fractures.     

Tibial fractures

Tibial fractures are common in small animal practice. As with other appendicular fractures, the patient's age, fracture location, and fracture type must be considered thoroughly. While methods for tibial fracture repair are similar to those used for appendicular fractures elsewhere, there are some unique considerations, both anatomically and functionally, that must be contemplated before repair. The following article will review the incidence of tibial fractures, tibial fracture types, and options for tibial fracture management and treatment. The use of external fixators, orthopedic bone plates, open reduction with internal fixation (ORIF), and external coaptation will be discussed. An emphasis will be placed on the most common types of tibial fractures, as well as those best suited for repair by general practitioners of veterinary medicine. Three case based examples will follow the overview.