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.     

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.     

Use of a condylar screw plate for repair of a Salter-Harris type-III fracture of the femur in a 2-year-old horse

A 2-year-old sexually intact male Paint horse weighing 427 kg (940 lb) was admitted for examination and treatment of intermittent non-weight-bearing lameness of the right hind limb of 1 week's duration. Radiography revealed a displaced Salter-Harris type-III fracture of the right femoral condyle with the sagittal component of the fracture line located in the intercondylar space and the transverse component exiting on the medial aspect of the femur. The fracture was repaired with a condylar screw plate designed for repair of femoral condylar fractures in humans. The owner reported by telephone 9 months after surgery that the horse was sound. To our knowledge, use of this particular implant system for fixation of a Salter-Harris type-III fracture on the medial side of the femur in a horse has not been described. Results in this horse suggest that this implant can be successfully used for repair of femoral condylar fractures in selected adult horses.     

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.     

ULTRASONOGRAPHIC ASSESSMENT OF FRACTURE HEALING AFTER PLATE OSTEOSYNTHESIS

The goals of this study were to assess the ability of ultrasonography (US) to assess uncomplicated fracture healing and to establish normal images. Twenty-two dogs, ranging in age from 6 to 180 months were studied. Body weight ranged from 2.2 to 60 kg. All fractures were treated by plate osteosynthesis. US (B-mode and power Doppler) and radiography were performed until both were consistent with complete healing. B-mode US was performed in all dogs, and power Doppler US in 14. Fracture healing was judged to be complete based on US earlier than when based on radiography. The tissue immediately adjacent to the plate appeared vascularized on power Doppler images at a time when the tissue at the fracture site had a negative power Doppler exam. US appears useful for assessment of primary fracture healing and power Doppler was useful for detecting vascularization at the fracture site in nonhealed fractures. Power Doppler interrogation should be performed away from any metal implant, as a result from an interrogation adjacent to an implant will not reflect actual vascularization at the fracture site.     

Repair of diaphyseal femoral fractures in cats using interlocking intramedullary nails: 12 cases (1996-2000).

OBJECTIVE: To determine the outcome of femoral fractures repaired with 4.0- and 4.7-mm interlocking intramedullary nails in cats. DESIGN: Retrospective study. ANIMALS: 12 cats with diaphyseal femoral fractures. PROCEDURE: Records of all cats in which the 4.0- and 4.7-mm interlocking nail system was used for repair of diaphyseal femoral fractures at the Animal Medical Center and Florida Veterinary Specialists between 1996 and 2000 were reviewed. Information included signalment, type of fracture, size of the implant, details of the surgery, intra- and postoperative complications, fracture healing, and clinical outcome. RESULTS: Femoral fractures in 12 cats were repaired. Eleven of the fractures were comminuted, with 2 of these being open. Clinical outcome was excellent in 7 cats, good in 3, and fair in 1. One resulted in a nonunion. Complications included screw breakage (1 cat) and fracture distal to the nail (1). Fracture distal to the nail occurred from a second trauma. CONCLUSION AND CLINICAL RELEVANCE: Use of the interlocking nail has been limited in cats because of the small diameter of the medullary canal. Use of the 4.0-mm nail will allow for greater application of this implant in small patients. Results of this study indicate that the 4.0- and 4.7-mm interlocking nails can be used to repair simple or comminuted diaphyseal femoral fractures in cats.     

Fracture repair of the distal portion of the radius by use of a condylar screw implant in an adult horse.

An 8-year-old American Quarter Horse gelding was evaluated because of an open fracture involving the left radius. The horse had fallen during training and became immediately non-weight-bearing in the left forelimb. On initial evaluation, the horse was unable to bear weight on that limb; radiography revealed a long oblique fracture of the distal metaphysis of the radius with minimal displacement of the fracture fragments. Because of the configuration of the fracture, we recommended surgical intervention with internal fixation. A condylar screw implant and 4.5-mm broad dynamic compression plate were applied to the medial and dorsolateral aspects of the radius, respectively. The horse recovered in a sling and full-limb bandage. Six months after discharge, the horse was reevaluated because of a grade 4/5 lameness in the same limb. Palpation revealed signs of severe pain over the distomedial aspect of the radius. Radiography of the left radius revealed severe osteolysis beneath the distal aspect of the condylar screw implant. Surgical removal of the medial plate was performed. Sixteen months after the initial fracture repair, the horse had returned to light training without signs of lameness. Removal of the dorsal plate may be indicated if this horse is to return to aggressive training or becomes lame in the left forelimb.     

BIODEGRADABLE IMPLANTS IN FRACTURE FIXATION IN SMALL ANIMAL SURGERY

The Finnish group led by Rokkanen and Tormala has developed a biodegradable implant for fracture fixation. Results from experimental and clinical studies of polyglycolic acid (PGA) are encouraging, and further studies are being made in the use the biorod, which has been used successfully to treat an avulsed calcaneal fracture in a puppy. Other biodegradable substances are being investigated to improve biodegradable fracture fixation devices.     

Biomechanics of fracture fixation failure

This article reviews the physiologic forces, stresses, and strains in normal bones. Biomaterials used in implants for fracture fixation devices are described, and the mechanical properties of an implant are discussed. The common mechanisms of implant failure are included.     

1例长颈鹿跖骨骨折的诊断和治疗

介绍1例长颈鹿跖骨骨折的诊断与治疗。患鹿左侧跖骨远端开放性横骨折,采用全身镇静配合神经传导阻滞麻醉和局部浸润麻醉,使用外固定支架进行骨折断端的恢复,植入物完成后采用氩弧焊焊接牢固,术后恢复良好。     

Risk Factors for Femoral Fracture after Canine Press‐Fit Cementless Total Hip Arthroplasty

Objective: To evaluate risk factors for femoral fracture after porous‐coated cementless total hip arthroplasty (THA). Study Design: Case series. Animals: Dogs (n=74) that had cementless THA (n=84). Methods: Medical records of dogs from 2 referral hospitals were reviewed for occurrence of postoperative femoral fracture. Patient and operative (age, breed, sex, weight, and canal flare index [CFI], indication for arthroplasty, intraoperative fissure, cerclage usage, and implant sizes) factors were analyzed. Assessment of implant positioning and canal fill was performed on immediate postoperative radiographs. Femoral fractures (n=11) were evaluated and compared with 73 cases without fracture that met the inclusion criteria. Results: Mean (±SEM) age was 7.30±0.69 years for dogs with, and 4.77±0.37 years for dogs without femoral fracture. Age was positively associated with fracture (P=.022). Mean (±SEM) CFI was 1.80±0.09 for dogs with, and 1.98±0.04 for dogs without fracture. CFI was negatively associated with fracture (P=.045). Body weight, intraoperative fissure, cerclage use, implant size, position, and canal fill did not influence the occurrence of femoral fracture. Conclusions: Older dogs and dogs with lower CFI may be at increased risk for femoral fracture after porous‐coated cementless THA. Clinical Relevance: Risk factors exist for femoral fracture after cementless THA using porous‐coated implants, and should be critically evaluated during the patient selection. These risks should be weighed against the benefits of the system, and measures to minimize femoral fracture in at‐risk patients studied.     

The effects of femur and implant position on the radiographic assessment of total hip femoral implants in dogs

OBJECTIVE: To determine the effect of femur positioning and femoral implant placement on the radiographic assessment of total hip femoral implants in dogs. STUDY DESIGN: Cadaveric study. ANIMALS: Five canine femurs. METHODS: Five canine femurs were fitted with total hip implants, in predetermined locations, postmortem. Each femur was moved through a defined range of motion and radiographed at specific intervals. Radiographs were then digitized, and implant position was measured using previously described methods. Regression analysis was conducted to determine whether varied femoral position resulted in a consistent (linear) pattern of change in the value of each particular measurement. RESULTS: Change in the position of the femur relative to the film cassette caused significant variation in the perceived position of the implant. The placement of the implant within the femur determined which measurements were affected and to what degree. CONCLUSIONS: The information obtained from standard clinical radiographs and conventional methods of quantitative analysis does not consistently provide an accurate assessment of the placement of the femoral implant within the femoral canal. Such data cannot be used to correlate implant position with implant failure.     

The effects of implant strategy on finished body weight of beef cattle

We summarized experimental data to quantify the change in final BW due to a particular implant strategy when cattle are adjusted to the same final body composition. The database developed for this study included 13 implant trials involving a total of 13,640 animals (9,052 steers and 4,588 heifers). Fifteen different implant strategies were used among these trials, including no implant (control), single implants, and combinations of implants. Individual carcass data collected at slaughter were used to calculate the adjusted final shrunk BW at 28% empty body fat (AFBW) for each treatment group within a trial, then the implant treatments were grouped into categories according to their effect on weight at 28% empty body fat (four groups for steers and two groups for heifers). All differences in AFBW between categories were significant (P < 0.01), indicating an incremental anabolic implant dose response in AFBW over unimplanted animals. Values for AFBW ranged from 520 kg in unimplanted steers to 564 kg in steers implanted and reimplanted with Revalor-S. For heifers, AFBW ranged from 493 kg in unimplanted heifers to 535 kg in heifers implanted and reimplanted with Revalor-H. After accounting for differences in mean BW and composition of gain, implanted steers and heifers had 4.2 and 3.1% higher apparent diet ME values, respectively. Increasing the anabolic implant dose increases the weight at which animals reach a common body composition. This study indicates that anabolic implant response is due to a combination of a reduced proportion of the DMI required for maintenance, reduced energy content of gain, and efficiency of use of absorbed energy.     

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.     

Excellent long-term clinical outcome in a young athletic dog following surgical complications of a comminuted patellar fracture and patellar ligament rupture

A 1-year-old athletic golden retriever dog was presented for a non-weight-bearing right pelvic limb lameness that occurred during a canicross race. Orthopedic examination revealed pain and inflammation of the right stifle joint. Radiographs showed a traumatic comminuted patellar fracture. Surgery was elected and a midsubstance patellar ligament rupture was also identified. Surgical management consisted of a combination of techniques for patellar fracture fixation and primary patellar ligament reconstruction. All orthopedic implants were removed secondary to implant failure. Postoperative 20-month radiographic follow-up revealed patella alta and non-union of the fracture. However, an excellent clinical outcome was achieved with a complete return to a high activity level.Key clinical message:Surgical stabilization of patellar fractures is usually a significant challenge. A return to apparent normal limb function was achieved in this dog suffering complex patellar fracture with concomitant patellar ligament rupture despite postoperative fracture non-union.     

Central tarsal implant in a racing greyhound

Although most type IV fractures in dogs can be treated with screw fixation, type V fractures usually lead to an unsuccessful clinical result. A central tarsal replacement composed of a titanium alloy was developed by our investigation team to treat type V fractures. The implant was used to successfully treat a greyhound and to allow it to return to racing. Continual development of this new surgical procedure hopefully will give the veterinarian predictable and reliable clinical results and return injured greyhounds to active racing.     

Open diagonal fracture of metatarsus III/IV and internal fixation in an alpaca

This report describes the case of a 15-month-old alpaca stallion with an open fracture of metatarsus (MT) III/IV that occurred during transportation. Despite of a guarded prognosis, the animal was operated on request of the owner. The surgical intervention consisted of meticulous lavage and curettage of the wound and affected bone, precise fracture reduction, internal fixation with a 12-hole broad 3.5 mm DCP and implantation of a gentamicin impregnated collagen sponge. Primary wound healing was evident and the implant was removed at 3 months after the initial intervention. At 14 months after surgery, the stallion did not show any signs of lameness and was used for service.     

Ulnar osteotomy for treatment of cubital subluxation,following locking compression plate osteosynthesis of a radius fracture in a foal

A closed mid‐diaphyseal fracture in a one‐day‐old foal was treated using a 3.5 mm locking compression plate on the cranial aspect of the radius. The foal showed good fracture healing, but a radio‐ulnar synostosis developed despite the absence of transfixation by any implant into the ulna. Four months after surgery the radiographs revealed a cubital subluxation, which was managed by an osteotomy of the ulna at the time of plate removal, allowing the ulna to adjust into a normal position. One year after surgery the foal was clinically sound; the radiographs showed good healing of the osteotomy gap as well as good remodelling of the radius; however, a slight elbow subluxation was present.     

Surgical versus conservative management of patella fractures in cats: a retrospective study

This study compared the clinical outcome in cats with patella fractures treated by surgery to those treated conservatively. Six cats with 9 patella fractures were treated. Six fractures were treated surgically and 3 were treated conservatively. Medical records of all 6 patients were reviewed for age, breed, gender, trauma, and fracture conformation. All patients had follow-up which consisted of a physical examination, radiographs, and an interview with the client between 1 and 4.5 y after surgery or diagnosis. All cats treated conservatively returned to normal activity with no gait abnormalities. In cats that had surgery, 4/6 had breakdown of the surgical repair but all cats went on to full recovery with normal activity and gait. The conclusions of this preliminary study are that surgical repair of cat patella fractures has a high rate of implant failure and that conservative management of cat patella fractures results in excellent clinical outcome.     

Mechanical testing of 3.5 mm locking and non-locking bone plates

Locking plate technologies are being developed in order to provide the surgeon with advantages over previous bone plate systems (both locking and non-locking). Locking plate systems possess inherent biological advantages in fracture fixation by preserving the periosteal blood supply, serving as internal fixators. It is important to consider the strength of each orthopaedic implant as an important selection criterion while utilizing the reported advantages of locking plate systems to prevent catastrophic fracture failure. Mechanical testing of orthopaedic implants is a common method used to provide a surgeon with insight on mechanical capabilities, as well as to form a standardized method of plate comparison. The purpose of this study was to demonstrate and to quantify observed differences in the bending strength between the LCP (Limited Contact Plate), LC-DCP, 3.5 mm Broad LC-DCP (Limited Contact Dynamic Compression Plate), and SOP (String of Pearls) orthopaedic bone plates. The study design followed the ASTM standard test method for static bending properties of metallic bone plates, which is designed to measure mechanical properties of bone plates subjected to bending, the most common loading encountered in vivo. Single cycle four point bending was performed on each orthopaedic implant. The area moment of inertia, bending stiffness, bending strength, and bending structural stiffness were calculated for each implant. The results of this study demonstrated significant differences (p<0.001) in bending strength and stiffness between the four orthopaedic implants (3.5 Broad LC-DCP>SOP>LCP=LC-DCP). The 3.5 mm LCP should be expected to provide in vivo strength and stiffness similar to a comparable LC-DCP. The SOP should provide strength and stiffness that is greater than a comparable LC-DCP but less than a 3.5 mm Broad LC-DCP.