In vitro biomechanical comparison of three methods for internal fixation of femoral neck fractures in dogs

The in vitro biomechanical properties of three methods for internal fixation of femoral neck fractures were evaluated. Fifty cadaveric femura from Beagle dogs were used. Ten intact femora served as controls. In 40 femura, an osteotomy of the femoral neck was performed to simulate a transverse fracture. With the remaining 30 femura, three repair methods (two medium Orthofix pins, a 2.7 mm cortical bone screw placed in lag fashion and an anti- rotational Kirschner wire, or three divergent 1.1 mm Kirschner wires) were used to stabilize the osteotomies, and 10 osteotomies were stabilised per repair method. These 30 femura where then subject to monotonic loading to failure. Construct stiffness and load to failure were measured. In the remaining 10 femura, pressure sensitive film was placed at the osteotomy site prior to stabilization with either two Orthofix pins (n = 5) or a screw placed in lag fashion (n = 5) to determine the compressive pressure (MPa), compressive force (KN) and area of compression (cm2). There was no significant difference in the stiffness or load to failure for the three repair methods evaluated. There was no significant difference in the compressive pressure, compressive force or area of compression in osteotomies stabilized with Orthofix pins and 2.7 mm bone screws.     

Modified intramedullary pin technique for repair of distal femoral physeal fractures in the dog and cat

A modified intramedullary pin technique for surgical repair of distal femoral physeal fractures in dogs and cats provided stability at the fracture site and allowed early range of motion. The fixation and stability of this technique was compared with that achieved with a multiple pin technique. Fixation failure did not occur in 11 animals treated by the modified intramedullary pin technique, whereas there were 2 failures in 13 patients treated by a multiple pin technique.     

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.     

Use of flexible intramedullary rods for fixation of femoral fractures in eight dogs

High-density, polysulfone rods were used to repair 4 comminuted and 4 short-oblique, mid-diaphyseal femoral fractures in 8 dogs. Bony union was achieved in 2 dogs at 10 and 12 weeks after surgery. In one dog, the femoral fracture was healing when amputation of the limb became necessary because of sciatic nerve damage secondary to an ipsilateral pelvic fracture. In a fourth dog, fracture repair resulted in nonunion, despite normal clinical function at 18 months after surgery. In the remaining 4 dogs (50%), the rods failed at 3.5, 4, 6, and 22 weeks after surgery. These fractures were then stabilized by use of other methods. Although several factors may have contributed to failure of the rods, multiple autoclaving of the thermoplastic implants may have caused embrittlement and subsequent breakage.     

Repair of femoral capital physeal fractures in 12 cattle

OBJECTIVE: To document signalment, clinical signs, and long-term outcome of surgical treatment for femoral capital physeal fractures in cattle. STUDY DESIGN: Retrospective study. Animals-Twelve cattle with femoral capital physeal fractures. METHODS: Cases were identified by a search of radiographic records. Historical, diagnostic, surgical, and outcome data were collected from the medical records. Owners were contacted for follow-up information by telephone. RESULTS: Fractures were repaired by screws inserted in lag fashion in 4 animals and by use of multiple intramedullary pins in 8 animals. Six of 12 animals required repeat surgery to reposition screws or pins. Nine animals were considered successfully treated at discharge. Six months after surgery, 6 of 11 animals for which follow-up was obtained were still sound. At 12 months, 4 of 4 animals alive were still sound. Animals that bore weight earliest postoperatively were more likely to have a successful outcome. Animals <12 months of age had better outcomes than animals >12 months of age. CONCLUSIONS: Prognosis for serviceable soundness is good in cattle <12 months of age and fair in animals >12 months of age after surgical repair of femoral capital physeal fracture by stacking intramedullary pins or by screws inserted in lag fashion. CLINICAL RELEVANCE: Surgical repair of femoral capital physeal fracture is most successful in younger cattle and can result in productive animals.     

Internal fixation of femoral capital physeal injuries in dogs: 40 cases (1979-1987)

Fractures of the femoral capital physis were stabilized with small pins or a lag screw in 36 dogs (4 bilateral injuries). Radiography was used to monitor the development of osteoarthritis in affected joints and narrowing of the femoral neck. More radiographic signs of arthritis (P less than 0.05) developed in the coxofemoral joints of dogs that were less than or equal to 4 months old when injured, compared with those in dogs greater than 4 months old. Of 40 capital physeal injuries, 35% had concurrent ipsilateral coxofemoral joint injuries and developed more radiographic signs of arthritis (P less than 0.05) than did those that had no other coxofemoral injury. Narrowing of the femoral neck developed in 70% of the healing capital physeal repairs, but in most dogs, narrowing was not associated with segmental collapse of the femoral neck. Neither time interval from injury to surgical fixation nor surgical approach used had an effect (P greater than 0.05) on the development of narrowing of the femoral neck.     

In vitro biomechanical properties of 2 compression fixation methods for midbody proximal sesamoid bone fractures in horses

OBJECTIVE: To evaluate 2 methods of midbody proximal sesamoid bone repair--fixation by a screw placed in lag fashion and circumferential wire fixation--by comparing yield load and the adjacent soft-tissue strain during monotonic loading. STUDY DESIGN: Experimental study. SAMPLE POPULATION: 10 paired equine cadaver forelimbs from race-trained horses. METHODS: A transverse midbody osteotomy of the medial proximal sesamoid bone (PSB) was created. The osteotomy was repaired with a 4.5-mm cortex bone screw placed in lag fashion or a 1.25-mm circumferential wire. The limbs were instrumented with differential variable reluctance transducers placed in the suspensory apparatus and distal sesamoidean ligaments. The limbs were tested in axial compression in a single cycle until failure. RESULTS: The cortex bone screw repairs had a mean yield load of 2,908.2 N; 1 limb did not fail when tested to 5,000 N. All circumferential wire repairs failed with a mean yield load of 3,406.3 N. There was no statistical difference in mean yield load between the 2 repair methods. The maximum strain generated in the soft tissues attached to the proximal sesamoid bones was not significantly different between repair groups. CONCLUSIONS: All repaired limbs were able to withstand loads equal to those reportedly applied to the suspensory apparatus in vivo during walking. CLINICAL RELEVANCE: Each repair technique should have adequate yield strength for repair of midbody fractures of the PSB immediately after surgery.     

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.     

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.     

Management of laterally displaced proximal tibial physeal fractures in three dogs

Fractures of the proximal tibial physis are uncommon in dogs, and are rarely associated with marked instability and lateral displacement of the proximal tibial epiphysis. Three dogs with proximal tibial physeal fractures demonstrating marked instability and lateral displacement were treated with two different principles of fixation. Healing of the physeal fracture was achieved with rigid internal fixation in one case, and with adaptational osteosynthesis supplemented with a temporary transarticular external skeletal fixator in two cases. Duration of surgery and technical difficulty was reduced using a modified adaptational osteosynthesis approach, suggesting that surgical treatment of these uncommon and challenging fractures may be more appropriately achieved by this technique.     

Determination of the insertion position of implants for the cross-pin fixation of distal femoral physis fractures

The cross-pin technique for the treatment of distal femoral physis fractures (specifically, Salter-Harris Type I fractures) was investigated using femurs collected from beagle cadavers. The pin was inserted from the medial surface of the femur at an inclination of approximately 30 to 45° relative to the long axis of the femur in the anteroposterior direction; the pin exit was set proximal to the origin of the long digital extensor tendon. Digital and radiographic images of the femur in the anteroposterior and lateral directions were obtained. In both types of images, the insertion angle of the pin relative to the long axis was measured. Results suggest that when inserting a pin proximal to the fracture line, the ideal position can be achieved by inclining the pin approximately 20° cranially relative to the long axis of the lateral direction of the femur, in addition to the previously described criteria.     

犬股骨骨折的诊断与治疗

犬骨折以四肢骨多发,多因外伤引起,也可因奔跑、扭闪、急停等肌肉强烈收缩而引发骨折或病理性骨折.本研究采用询问病史、体格检查和x线检查等方法对1只7月龄苏格兰牧羊犬的股骨远端骨折进行诊断,应用髓内针内固定方法对该病犬进行治疗.过程如下:该犬主人在室外溜犬时,一辆出租车将该犬撞倒,主人将其带回家后,发现该犬右后肢不敢着地,用手触摸右后肢,犬躲避、惨叫,并伴有精神沉郁,喜卧,食欲减退.体格检查,该犬站立时右后肢不敢着地,行走时3肢跳跃前进;心、肺、腹部检查未发现异常;2前肢和左后肢运动和感觉均正常,右后肢膝关节上方明显肿胀,拒绝触摸;右后肢侧位X光片显示股骨远端骨干骨折,并且有明显的移位,膝关节正常;血常规脸查正常.综合病史、体格检查和X线检查结果,诊断为犬股骨骨折.应用髓内针内固定方法对该病犬进行治疗,术后石膏外固定患肢,全身应用抗生素,加强护理.手术1个月后,该犬已能正常行走,恢复良好.     

Bone plate fixation of distal radius and ulna fractures in small- and miniature-breed dogs.

Bone plate fixation was reviewed in 29 distal radial fractures of small- and miniature-breed dogs. Twenty-two fractures in 18 dogs were available for follow-up. Number of complications and return to function were evaluated. Complications occurred in 54% of the fractures. Catastrophic complications occurred in 18% of fracture repairs with follow-up, while minor complications occurred in 36%. Sixteen (89%) of 18 dogs had a successful return to function. Bone plate fixation is a successful repair method for distal radius and ulna fractures in small-breed dogs, compared to previously reported methods.     

犬股骨骨折的内固定法

骨折是骨或软骨的完整性或连续性因外力机械性作用而遭受破坏.骨折常伴有周围软组织不同程度的损伤.在小动物外科疾病中,骨骼与关节疾病比较常见,其中以骨折,尤其后肢股骨骨折发病率为最高,约占全部骨折的32%[1-3].     

Use of reconstruction plates for repair of acetabular fractures in 16 dogs

Acetabular fractures in 16 dogs were repaired using reconstruction plates. Notches cut into the plate permitted contouring in three planes to facilitate accurate articular reconstruction. There were three cranial, seven central, one caudal and five comminuted acetabular fractures. These acetabular fractures were invariably associated with multiple pelvic fractures. Repair of nonacetabular fracture/luxation was indicated in 10 cases. Follow-up information was available for 15 dogs, of which 12 (80 per cent) had an excellent or good outcome. Fracture configuration and the presence of multiple fractures did not influence prognosis. Two dogs died suddenly, late in convalescence, but the cause of death was not established.