STRESS FRACTURES OF THE HUMERUS, RADIUS, AND TIBIA IN HORSES

The medical records, radiographic and nuclear scintigraphic findings of 26 racing horses with 27 stress fracture episodes of the humerus, radius, or tibia were reviewed. The purposes of this study were to describe the radiographic and/or scintigraphic features of stress fractures of the humerus, radius, or tibia, and to evaluate the signalment and history of horses in which stress fracture occurred. Stress fractures of the three long bones examined were primarily seen in 2-and 3-year-old male Thoroughbred horses; commonly, the onset of lameness was immediately following training gallops or racing. There were 13 humeral stress fracture episodes in 12 horses. Ten were in the proximal caudolateral cortex, and three were in the distal craniomedial cortex. Radial stress fractures were seen in three horses, all in the midshaft radius. Tibial stress fractures were diagnosed in 11 horses. They were located in the proximal lateral tibia in six horses, the distal caudolateral tibia in three horses, and the midshaft tibia in three horses. Fifteen stress fractures were diagnosed with radiographs alone, one was diagnosed with scintigraphy alone, nine were diagnosed with radiographs and scintigraphy, and, in two horses, radiographs were negative, but the scintigraphic findings were consistent with stress fracture.     

INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE IN VIETNAMESE POT-BELLIED PIGS

The purpose of this study was to evaluate the occurrence of humeral condylar fractures in Vietnamese pot-bellied pigs and to postulate a possible predisposing cause for these fractures. Thirteen Vietnamese pot-bellied pigs (Group A) were evaluated over an eight year period (1990-1998), each with a history of either a unilateral or bilateral forelimb lameness. The cause of lameness was localized to the elbow region. Of the thirteen pigs, twenty-one elbows were evaluated radiographically. Pigs ranged in age from six months to four years old. All pigs over the age of seven months showed radiographic evidence of elbow degenerative joint disease. Fractures involving the medial aspect of the humeral condyle were identified in 8/21 studies (38%). A well-defined linear intracondylar articular lucency was identified in 7/21 studies (33%) on the craniocaudal projection. The site of this lucency corresponded to the location of the articular component of the fractures seen involving the humeral condyle. The elbows of five pot-bellied pigs with no known history of forelimb lameness or trauma (Group B) were evaluated radiographically following euthanasia. All five pigs were of unknown age and gender. An intracondylar vertical linear lucency was identified bilaterally in three pigs (60%). Concurrent degenerative joint disease was present in all instances. The remaining two pigs were radiographically normal. Computed tomography of the elbows was performed in one affected pig from Group B. The radiographic findings in this pig were verified. Histopathology of the right elbow of this affected pig was diagnostic for incomplete endochondral ossification of the humeral condyle. A similar condition involving the humeral condyle has been previously described in Cocker and Brittany Spaniels. These canine breeds also have a high incidence of humeral condylar fractures. It is postulated that Vietnamese pot-bellied pigs are similarly prone to humeral condylar fractures, even in the absence of known trauma, due to incomplete ossification of the humeral condyle.     

Evaluation of surgical repair of humeral condylar fractures using self-compressing orthofix pins in 23 dogs

OBJECTIVE: To report short- and long-term clinical and radiographic outcomes in dogs with humeral condylar fractures repaired using self-compressing Orthofix pins. STUDY DESIGN: Retrospective evaluation with solicited long-term clinical and radiographic evaluations. ANIMALS: Twenty-three dogs with humeral condylar fractures. METHODS: Medical records and radiographs were reviewed. Owners were asked to return dogs for long-term clinical and radiographic evaluation. RESULTS: Dogs were aged 1.5-26 months (mean+/-SD, 5.8+/-5.0 months) with 20 dogs weighing <5 kg (mean, 3.6+/-2.8 kg). Of 21 dogs with immediate post-operative radiographs, 10 had anatomic reduction with the rest having either a step and/or gap at the articular surface. Kirschner wire migration and implant loosening were the most common post-operative complications. All fractures with adequate follow-up radiographic evaluations achieved union. Twelve of 13 dogs returned for long-term evaluation (mean, 19.0+/-18.5 months) were either sound (10 dogs) or had subtle, weight-bearing lameness (2). Fourteen dogs had radiographs >/=75 days after surgery (mean, 18.7+/-18.3 months), 8 dogs (57%) had no radiographic evidence of osteoarthritis (OA; mean OA score, 0.8; median 0), and all dogs had good or excellent limb function. CONCLUSIONS: Self-compressing Orthofix pins are suitable implants for the stabilization of humeral condylar fractures in small breed dogs. Implants were convenient and simple to use and complications were easily resolved. Dogs consistently had good long-term clinical and radiographic outcomes with no or minimal lameness and OA. CLINICAL RELEVANCE: Self-compressing Orthofix pins should be considered for the repair of humeral condylar fractures in small breed dogs.     

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.     

Risk factors for humeral condylar fractures in the dog: A retrospective study

Humeral condylar fractures have fracture lines that extend through the joint surface and through one or both epicondyles. One hundred and eighty-nine dogs with humeral condylar fractures are presented in this study. Lateral condylar fractures were the most frequent (67 per cent), occurring nearly 10 times as often as the medial condylar fracture. Intercondylar fractures represented about 35 per cent of these. Condylar fractures occur as a result of moderate trauma and only rarely due to traffic accidents. The histories and circumstances of the three fracture types are not essentially different. Dogs, three and four months old, were strongly over-represented among the lateral and medial condylar fractures, compared with the age distribution of other types of fractures in the extremities of the dogs. Humeral condylar fractures were recorded in 58 breeds. All dogs are vulnerable to humeral condylar fractures. All sizes and both sexes are equally at risk. Some breeds seem to be more vulnerable to lateral condylar fractures: English and French bulldogs, Yorkshire terriers, miniature schnauzers, Gordon setters and German short-haired pointers. The St Bernard seems to be more vulnerable to medial and intercondylar fractures and the German shepherd dog and beagle to intercondylar fractures. A retrospective case control study does not provide wholly reliable statistical information on risk factors, and the statistics concerning breed and breed size must be judged accordingly. The method was considered to be the best statistical model available for this study.     

Intramedullary interlocking nail stabilisation of 21 humeral fractures in 19 dogs and one cat

OBJECTIVE: To assess the suitability of the intramedullary interlocking nail to stabilise humeral diaphyseal fractures in dogs and cats. METHOD: This multi-centre study retrospectively examined medical records, between June 1994 and May 2001, of 19 dogs and one cat, in which a total of 21 humeral fractures were stabilised with intramedullary interlocking nails. RESULTS: Animals ranged in body-weight from 4 to 97 kg. Eighteen (86%) of the fractures were comminuted. Adjunctive stabilisation was used in twelve (57%) fractures and bone grafts in nine (43%) fractures. A rapid return of function was noted in the majority of animals, with 14 (67%) having good or excellent function within four days of surgery. In two fractures the repair collapsed when a single proximal transcortical screw was placed cranial to the tricipital line of the humerus. This suggests that if a single transcortical screw is placed proximally the screw should be distal or caudal to the tricipital line in order to engage sufficient cortical bone. Eighteen (86%) of the fractures healed when stabilised with intramedullary interlocking nails. Three fractures did not heal. One was in a dog where a pathological fracture was temporarily stabilised with an intramedullary interlocking nail, one in a dog that died of an abdominal crisis three weeks after surgery and one in a dog in which fracture stabilisation collapsed due to incorrect implant selection. CONCLUSION: Intramedullary interlocking nails are well suited to the stabilisation of humeral diaphyseal fractures in dogs and cats.     

The incidence of humeral condylar fractures in the dog: a survey of seventy-nine cases

A review of 79 cases of canine humeral condylar fractures was made to establish the distribution of breed, age and cause of injury and to correlate these with the fracture type.     

Humeral stress remodelling locations differ in Thoroughbred racehorses training and racing on dirt compared to synthetic racetrack surfaces

Reasons for performing study: Veterinarians have observed a putative change in the location of humeral stress remodelling in Thoroughbred racehorses with change from dirt to synthetic racetrack surfaces. Objectives: To determine whether the location and severity of humeral stress remodelling differs between Thoroughbred racehorses exercising on dirt and synthetic racetrack surfaces, the potential significance of different locations of stress remodelling, and the potential usefulness of scintigraphy for prevention of complete humeral fracture. Methods: Scintigraphic images of humeri from 841 Thoroughbred racehorses at 3 racetracks during 2 years before and after conversion from dirt to synthetic surfaces were evaluated for location and severity of lesions. The effects of surface on lesion distributions were examined using Chi‐square or Fisher's exact tests. Archived fractured humeri were examined to determine the location and severity of stress remodelling associated with complete fracture. Databases were queried to determine whether racehorses with scintigraphic lesions suffered humeral fracture and whether racehorses with a complete humeral fracture had had a scintigraphic examination. Results: Horses at synthetic racetracks had a greater proportion of distal humeral lesions, whereas horses at dirt racetracks had a greater proportion of caudoproximal lesions (P<0.001). Proximal lesions were more likely to be severe than distal lesions (P<0.001). Most complete fractures were associated with caudoproximal lesions, which were more often severe than distal lesions (P = 0.002). None of the horses with a scintigraphic lesion had a complete humeral fracture. None of the horses with a complete humeral fracture underwent scintigraphic examination. Conclusions: Race surface affected humeral scintigraphic lesion location and hence the location of stress remodelling. Lesion severity was associated with lesion location. Complete humeral fracture was associated with caudoproximal stress remodelling and lack of scintigraphic examination. Potential relevance: Risk for complete humeral fracture may be lower on synthetic surfaces than on dirt surfaces, and, by inference, for horses examined using scintigraphy.     

Salter-Harris type III fractures of the distal humerus in two dogs

Salter-Harris type III fractures of the distal humerus in a four-month-old male Labrador Retriever and a male crossbreed dog (estimated to be 3.5-months-old) are reported. Both fractures were treated with open reduction and interfragmentary compression by lag screw fixation. Both fractures healed and full limb use was regained at four weeks postoperatively. The occurrence of this unusual fracture type may be related to the physeal closure pattern of the distal humeral physis, and a different mechanism of injury compared to the more common Salter-Harris type IV fracture seen in this region.     

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.     

Fractures, dislocations and contusions in the Borneon orang utan (Pongo pygmaeus pygmaeus)--a review of 21 cases

The clinical features, radiographic findings and management of traumatic lesions in the orang utan are described with reference to 21 cases. Eight cases had fractures of the femur and five had humeral fractures; all the fractures were successfully treated. One case with a skull fracture (frontal parietal) died before treatment could be instigated. Five orang utans with contusions recovered with symptomatic treatment and rest.     

Management of humeral and femoral fractures in dogs and cats with linear- circular hybrid external skeletal fixators

Linear-circular hybrid fixators were used to stabilize humeral and femoral fractures in 21 dogs and five cats. Twenty-two of 24 fractures with sufficient follow-up radiographic evaluation obtained union. Time to radiographic union ranged from 25 to 280 days (mean +/- standard deviation [SD] 110+/-69 days; median 98 days). Eleven animals developed minor and two dogs developed major pin and/or wire tract inflammation. Functional outcome was rated as excellent (n=16), good (n=5), and fair (n=3) at the time of final long-term assessment (range 4.5 to 60.0 months; mean +/- SD 28.4+/-15.4 months; median 28.5 months). Follow-up information was unavailable for two animals. Hybrid fixators were useful constructs for stabilization of humeral and femoral fractures, particularly fractures with short, juxta-articular fracture segments.     

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.     

Incomplete Ossification of the Humeral Condyle in Spaniels

An evaluation of 157 dogs with humeral fractures was performed. Cocker spaniels were more likely to have humeral condylar fractures (HCFs) than other breeds ( P < .0001). Male cocker spaniels were at increased risk ( P < .001). Cocker spaniels had more bilateral HCFs than other breeds of dogs ( P < .001). Eighteen dogs (17 purebred spaniels and 1 crossbred spaniel) with HCFs of unknown cause or occurring with normal activity were further studied, using radiography of their humeral condyle bilaterally (n = 18), computed tomography (n = 3), biopsy (n = 2), bone scintigraphy (n = 2), and genetic evaluation (n = 8). Fourteen of these 18 dogs had a nonfractured contralateral condyle. Twelve (86%) of the 14 nonfractured humeral condyles had a radiolucent line within the center of the condyle, 13 (93%) had radiographic signs of degenerative joint disease and an abnormal medial coronoid process, and six (43%) had periosteal proliferation involving the lateral epicondyle. Examination of biopsy samples from the fracture sites of two cocker spaniels showed fibrous tissue present at the fracture surfaces. The results of this study suggest an association between incomplete ossification of the humeral condyle in cocker spaniels and Brittany spaniels and a high prevalence of HCFs. Eight affected cocker spaniels with available pedigree information were found to be genetically related, suggesting that incomplete ossification of the humeral condyle may be a genetic disease with a recessive mode of inheritance.     

Distal Humeral Salter Harris (Type II) Fracture Repair by an Ulnar Osteotomy Approach in a Horse

Objectives: To report repair of a comminuted distal humeral type II Salter–Harris fracture using an ulnar osteotomy approach and locking compression plates (LCP). Study Design: Case report. Animal: A 3‐month‐old Standardbred filly with a type II Salter–Harris fracture of the distal humerus. Methods: Radiographic and computed tomography examinations were performed to assist surgical planning. The distal humeral fracture was approached by an ulnar osteotomy and repaired using a 7‐hole broad LCP and screws inserted in lag fashion. The osteotomy was subsequently repaired using a 7‐hole narrow LCP. Results: The distal humeral fracture was successfully approached and stabilized by an ulnar osteotomy approach. At 6‐month follow‐up, the filly was ambulating comfortably with a normal cosmetic appearance. Conclusions: An ulnar osteotomy approach was readily performed and allowed for repair of a type II Salter–Harris fracture of the distal humerus. Clinical Relevance: The equine distal humerus can be accessed readily using an ulnar osteotomy approach. LCPs allow for repair of complicated fractures that have previously been associated with a grave prognosis.     

A survey of bone fractures in the cat

A survey of 108 bone fractures in the cat was made over a 1 year period in a city practice in south west England. Seventy-three per cent involved the pelvic limb. The three bones most commonly affected were femur (38%), pelvis/sacrum (22%) and mandible (16%). Forty-five cases were the result of road accidents and 75% of cats were 2 years old or less.
Treatment of femoral shaft fractures by intramedullary pinning gave good results. The majority of proximal epiphyseal separations and femoral neck fractures responded well to conservative treatment. 'Cage rest' was used successfully to treat severely comminuted femoral shaft fractures. All cases of pelvic fracture were treated conservatively (up to 3 weeks 'cage rest'). Separation of the mandibular symphysis and fracture of the horizontal ramus healed readily. Repair of tibial (10%) and humeral (5%) fractures was without complications.     

Stress fractures of the tibia and humerus in Thoroughbred racehorses: 99 cases (1992-2000)

OBJECTIVE: To determine clinical characteristics of and outcome in Thoroughbred racehorses with tibial or humeral stress fractures. DESIGN: Retrospective study. ANIMALS: 99 Thoroughbreds with tibial or humeral stress fractures. PROCEDURE: Information obtained from the medical records included history, signalment, and clinical, radiographic, and scintigraphic findings. Outcome was determined by interviewing trainers, performing follow-up examinations, and analyzing race records. RESULTS: Seventy-four tibial stress fractures were identified in 61 Thoroughbreds, and 48 humeral stress fractures were identified in 39 Thoroughbreds (1 horse was included in both groups). Tibial stress fractures occurred most commonly in 2-year-old or unraced horses. Fractures were located in 1 of 3 sites in the tibia (most commonly, the caudolateral cortex of the mid-diaphysis) and 1 of 4 sites in the humerus (most commonly, the caudodistal cortex). Forty-four of 58 (76%) tibial stress fractures and 18 of 32 (56%) humeral stress fractures were identified radiographically. Humeral stress fractures involving the caudodistal cortex were not detected radiographically. Treatment consisted of rest and exercise restriction, and 49 of 61 (80%) horses with tibial stress fractures and 30 of 39 (77%) horses with humeral stress fractures returned to racing. Humeral stress fractures recurred in 6 horses. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that in Thoroughbred racehorses, tibial stress fractures occurred most commonly in unraced 2 year olds, whereas humeral fractures occurred most commonly in older horses that had raced previously. The prognosis for racing following treatment was good.     

An association between complete and incomplete stress fractures of the humerus in racehorses.

Twenty-one horses had a complete unilateral humeral fracture during race training or racing at a California racetrack during the period 24 February 1990 to 10 July 1991. Fractures occurred approximately equally in left and right limbs, and in males and females. Most fractures occurred during training, and in 2- and 3-year-old horses. Only 5 of 16 Thoroughbred horses with known racing records had previously raced more than once, and their mean time between races was less than the time between their last race and fracture (P = 0.07). Ten of 13 humeri studied further had gross evidence of periosteal callus bridging one portion of the fracture line, indicative of a pre-existing stress fracture.     

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.     

昆明犬胫腓骨骨折的诊治

本研究通过回顾分析临床上使用外固定支架治疗11例昆明犬胫腓骨骨折病例,探讨使用外固定支架治疗昆明犬胫腓骨骨折的临床效果。手术后100 d回访,骨折全部愈合,骨折愈合最短时间为30 d,最长为90 d,除少数有针孔感染和固定针松动外,无其他重大并发症。结果表明,外固定支架是治疗昆明犬胫腓骨骨折的理想方法。