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Whitton RC, Mirams M, Mackie EJ, Anderson GA, Seeman E. Exercise-induced inhibition of remodelling is focally offset with fatigue fracture in racehorses. Osteoporos Int 2013; 24:2043-8. [PMID: 23371360 DOI: 10.1007/s00198-013-2291-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 12/14/2012] [Indexed: 11/26/2022]
Abstract
UNLABELLED Bone remodelling is inhibited by high repetitive loading. However, in subchondral bone of racehorses in training, eroded surface doubled in association with fatigue fracture and there was greater surrounding trabecular bone volume suggesting trabecular modelling unloads the bone focally, allowing damage repair by remodelling. INTRODUCTION Remodelling replaces damaged bone with new bone but is suppressed during high magnitude repetitive loading when damage is most likely. However, in cortical bone of racehorses, at sites of fatigue fracture, focal porosity, consistent with remodelling, is observed in proportion to the extent of surrounding callus. Focal areas of porosity are also observed at sites of fatigue damage in subchondral bone. We hypothesised that fatigued subchondral bone, like damaged cortical bone, is remodelled focally in proportion to the modelling of surrounding trabecular bone. METHODS Eroded and mineralizing surfaces and bone area were measured using backscattered scanning electron microscopy of post-mortem specimens of the distal third metacarpal bone in 11 racehorses with condylar fractures (cases) and eight racehorses in training without fractures (controls). RESULTS Cases had a two-fold greater eroded surface per unit area at the fracture site than controls (0.81 ± 0.10 vs. 0.40 ± 0.12 mm(-1), P = 0.021) but not at an adjacent site (0.22 ± 0.09 vs. 0.30 ± 0.11 mm(-1), P = 0.59). Area fraction of surrounding trabecular bone was higher in cases than controls (81 ± 2 vs. 72 ± 2 %, P = 0.0020) and the eroded surface at the fracture site correlated with the surrounding trabecular area (adjusted R (2) = 0.63, P = 0.0010). CONCLUSION In conclusion, exercise-induced inhibition of remodelling is offset at sites of fatigue fracture. Modelling of trabecular bone may contribute to unloading these regions, allowing repair by remodelling.
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Affiliation(s)
- R C Whitton
- Faculty of Veterinary Science, Equine Centre, University of Melbourne, 250 Princes Hwy, Werribee, Victoria 3030, Australia.
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Dyson PK, Jackson BF, Pfeiffer DU, Price JS. Days lost from training by two- and three-year-old Thoroughbred horses: a survey of seven UK training yards. Equine Vet J 2009; 40:650-7. [PMID: 19165934 DOI: 10.2746/042516408x363242] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY The first major epidemiological study of injury incidence in the UK flat racing Thoroughbred (TB), published in 1985, found lameness to be the single largest reason for days when horses failed to train. It was considered advisable to ascertain if progress has been made in reducing the problem of musculoskeletal injuries in the intervening period. OBJECTIVE To quantify injury incidence and days lost from training by 2- and 3-year-old TBs in UK training yards during 2002 and 2003. METHODS One-hundred-and-eighty-two yearling TBs were recruited at the end of 2001 and daily training and injury records maintained over the following 2 training and racing seasons. Days were defined as lost from training when a horse failed to train at a slow canter speed or faster, and could be assigned to one of 4 categories: lameness, medical, traumatic and unknown. The incidence and number of days lost due to specific injuries and medical conditions was determined by further subdividing the lameness and medical categories. RESULTS The study period provided a total of 52,601 2-year-old and 29,369 3-year-old days available for training, with 2-year-olds failing to train on a significantly greater proportion of days available than 3-year-olds. Lameness was the most important condition causing horses to miss training, with stress fractures being the most important cause of lameness. Medical conditions were a relatively minor cause of days lost from training, accounting for approximately 5% of untrained days in the 2 age groups. CONCLUSIONS In UK flat racehorses there has been little change in the proportion of days lost from training due to lameness over the last 20 years. POTENTIAL RELEVANCE This study highlights the need for further efforts to reduce the problem of lameness in the racing TB.
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Affiliation(s)
- P K Dyson
- Department of Veterinary Clinical Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK
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3
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Verheyen KLP, Newton JR, Price JS, Wood JLN. A case-control study of factors associated with pelvic and tibial stress fractures in Thoroughbred racehorses in training in the UK. Prev Vet Med 2006; 74:21-35. [PMID: 16473420 DOI: 10.1016/j.prevetmed.2006.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Few epidemiological studies have investigated risk factors for musculoskeletal injury occurring in Thoroughbred racehorses during training, although it is the major cause of wastage in the racing industry. We recently conducted a large-scale epidemiological study to estimate the incidence of fracture in racehorses in training in the UK and to identify associated risk factors. Thirteen racehorse trainers provided data on horses in their care, with daily recording of training information and provision of details on any fractures incurred. Data were collected for 2 years, including two consecutive flat racing seasons (1999 and 2000). This paper describes findings from a nested case-control study investigating factors associated with the occurrence of pelvic and tibial stress fractures in our study population. Cases were identified from the main study and defined as horses with a pelvic or tibial stress fracture, confirmed through routine diagnostic imaging. Randomly selected controls were matched on date of fracture in the case. Age and gender of the horse, its exercise history and training surfaces were examined as explanatory variables. Exercise was quantified as cumulative distances cantered and worked at high speed in 30- and 60-day periods prior to date of fracture in the case. Conditional logistic regression was used to construct multivariable models for the 30- and 60-day periods, respectively. We hypothesised that larger cumulative exercise distances would be associated with an increased risk of pelvic or tibial stress fracture and that different training surfaces would be associated with differences in fracture risk. In the 30-day period, when adjusting for trainer, the risk of pelvic or tibial stress fracture increased with increasing distance cantered, reaching a peak at around 50 km, after which the risk reduced. This trend was not obvious in the 60-day period, with no significant association between exercise distances and risk of stress fracture. Predominant use of one particular sand-based all-weather surface was related to an increased risk of pelvic or tibial stress injury, although this finding should be interpreted with caution. Surface maintenance and construction may play a role; variables that were not considered in the current analyses, which were based on a relatively small number of cases. Trainer was associated with differences in stress fracture risk after adjusting for exercise distances and surface but age and gender were not.
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Affiliation(s)
- K L P Verheyen
- Animal Health Trust, Epidemiology Unit, Lanwades Park, Kentford, Newmarket CB8 7UU, UK.
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Muir P, McCarthy J, Radtke CL, Markel MD, Santschi EM, Scollay MC, Kalscheur VL. Role of endochondral ossification of articular cartilage and functional adaptation of the subchondral plate in the development of fatigue microcracking of joints. Bone 2006; 38:342-9. [PMID: 16275175 DOI: 10.1016/j.bone.2005.08.020] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 07/27/2005] [Accepted: 08/23/2005] [Indexed: 11/15/2022]
Abstract
The mechanisms that regulate functional adaptation of the articular ends of long bones are poorly understood. However, endochondral ossification of articular cartilage and modeling/remodeling of the subchondral plate and epiphyseal trabeculae are important components of the adaptive response. We performed a histologic study of the distal end of the third metacarpal/metatarsal bone of Thoroughbreds after bones were bulk-stained in basic fuchsin and calcified sections were prepared. The Thoroughbred racehorse is a model of an extreme athlete which experiences particularly high cyclic strains in distal limb bones. The following variables were quantified: microcrack boundary density in calcified cartilage (N.Cr/B.Bd); blood vessel boundary density in calcified cartilage (N.Ve/B.Bd); calcified cartilage width (Cl.Cg.Wi); duplication of the tidemark; and bone volume fraction of the subchondral plate (B.Ar/T.Ar). Measurements were made in five joint regions (lateral condyle and condylar groove; sagittal ridge; medial condylar and condylar groove). N.Cr/B.Bd was site-specific and was increased in the condylar groove region; this is the joint region from which parasagittal articular fatigue (condylar) fractures are typically propagated. Formation of resorption spaces in the subchondral plate was co-localized with microcracking. N.Ve/B.Bd was also site-specific. In the sagittal ridge region, N.Ve/B.Bd was increased, Cl.Cg.Wi was decreased, and B.Ar/T.Ar was decreased, when compared with the other joint regions. Multiple tidemarks were seen in all joint regions. Cumulative athletic activity was associated with a significant decrease in B.Ar/T.Ar in the condylar groove regions. N.Cr/B.Bd was positively correlated with B.Ar/T.Ar (P < 0.05, r(s) = 0.29) and N.Ve/B.Bd was negatively correlated with B.Ar/T.Ar (P < 0.005, r2 = 0.14) and Cl.Cg.Wi (P < 0.05, r2 = 0.07). We conclude that endochondral ossification of articular cartilage and modeling/remodeling of the subchondral plate promote initiation and propagation of site-specific fatigue microcracking of the joint surface, respectively, in this model. Microcracking of articular calcified cartilage likely represents mechanical failure of the joint surface. Propagation of microcracks into the subchondral plate is a critical factor in the pathogenesis of articular condylar fatigue (stress) fracture. Functional adaptation of the joint likely protects hyaline cartilage from injury in the short-term but may promote joint degeneration and osteoarthritis with ongoing athleticism.
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Affiliation(s)
- P Muir
- Comparative Orthopaedic Research Laboratory, School of Veterinary Medicine, 2015 Linden Drive, Madison, WI 53706, USA.
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5
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Abstract
Two 2-year-old pacers, a 3-year-old pacer and a 2-year-old-trotter with acute forelimb lameness were admitted for nuclear scintigraphic examination. Horses were grade 3-4/5 lame. There was increased radiopharmaceutical uptake (IRU) in the distal cranial medial aspect of the humerus in one horse and along the caudal humeral cortex in the other three horses. Two of the four horses were affected bilaterally. Radiographic abnormalities consisted of thickening of the caudal cortex of the mid-diaphysis of the humerus but radiographic changes were not present in all horses. All horses were managed with stall rest initially then stall rest with hand-walking followed by limited turn out for a total of four months. None of the horses had raced before injury. One horse has returned to race training and the other three horses have returned to racing. Average time to return to racing was 329 days. Humeral stress fractures in Standardbred horses are rare. Diffuse patterns of IRU have not been reported in the humerus and are likely indicative of severe stress remodeling. Standardbred racehorses with stress fractures or stress remodeling of the humerus appear to have a good prognosis for return to racing.
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Affiliation(s)
- Beth M Kraus
- Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Road, Kennett Square, PA 19348, USA.
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Abstract
REASONS FOR PERFORMING STUDY Musculoskeletal injury is the major cause of days lost from training and wastage in Thoroughbred racehorses. Little scientific information is available on the majority of injuries occurring in training. OBJECTIVES To estimate the incidence of fractures in British racehorses in training and describe the occurrence of different fracture types and bones involved. METHODS Thirteen UK racehorse trainers participated in a prospective study, providing data on horses in their care for 2 years. Details on horses, their daily exercise and fracture occurrence were recorded. RESULTS A total of 1178 horses provided 12,893 months at risk. Nontraumatic fracture incidence was 1.15/100 horse months (95% CI = 0.98, 1.35) and 78% of fractures occurred during training. A wide variety of fracture types and bones were involved, although at least 57% were stress fractures. Pelvic and tibial stress injuries accounted for 28% of fractures diagnosed. CONCLUSIONS It is important to study injuries in training as well as in racing. The number of stress fractures suggests that training regimes for young Thoroughbreds could often be improved to create a more robust skeleton, able to withstand injury. POTENTIAL RELEVANCE Studying injuries in racehorses in training can provide a scientific basis for the design of safer training regimes.
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Affiliation(s)
- K L R Verheyen
- Epidemiology Unit, Animal Health Trust, Lanwades Park, Kentford, Suffolk CB8 7UU, UK
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Skedros JG, Sybrowsky CL, Parry TR, Bloebaum RD. Regional differences in cortical bone organization and microdamage prevalence in Rocky Mountain mule deer. Anat Rec A Discov Mol Cell Evol Biol 2003; 274:837-50. [PMID: 12923894 DOI: 10.1002/ar.a.10102] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The limb bones of cursorial mammals may exhibit regional structural/material variations for local mechanical requirements. For example, it has been hypothesized that mineral content (%ash) and secondary osteon population density (OPD) progressively change from proximal (e.g., humerus) to distal (e.g., phalanx), in accordance with corresponding progressive changes in stress and mechanical/metabolic cost of functional use (both greatest in the distal limb). We tested this hypothesis in wild-shot Rocky Mountain mule deer by examining transverse segments from mid-diaphyses of medial proximal phalanges, principal metacarpals, radii, and humeri, as well as the lateral aspects of sixth ribs from each of 11 mature males. Quantified structural parameters included the section modulus (Z), polar moment of inertia (J), cortical area/total area ratio (CA/TA), bone girth, and cortical thickness. In addition, %ash and the prevalence of in vivo microcracks were measured in each bone. Thin sections from seven animals were further examined for OPD and population densities of new remodeling events (NREs). Results showed a significant progressive decrease in %ash from the humerus (75.4% +/- 0.9%) to the phalanx (69.4% +/- 1.1%) (P < 0.0001), with general proximal-to-distal increases in OPD and general decreases in J and Z. Thirteen microcracks were identified in the rib sections, and only two were observed in the limb bones. Although the ribs had considerably greater NREs, no significant differences in NREs were found between the limb bones, indicating that they had similar remodeling rates. Equivalent microcrack prevalence, but nonequivalent structural/material organization, suggests that there are regional adaptations that minimize microcrack production in locations with differences in loading conditions. The progressive proximal-to-distal decrease in %ash (up to 6%); moderate-to-high correlations between OPD, %ash, J, and CA/TA; and additional moderate-to-high correlations of these parameters with each bone's radius of gyration support the possibility that these variations are adaptations for regional loading conditions.
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Affiliation(s)
- John G Skedros
- Department of Veterans Affairs Medical Center, Salt Lake City, Utah, USA.
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Tapprest J, Audigie F, Radier C, Anglade MC, Voisin MC, Foucher N, Collobert-Laugier C, Mathieu D, Denoix JM. Magnetic resonance imaging for the diagnosis of stress fractures in a horse. Vet Radiol Ultrasound 2003; 44:438-42. [PMID: 12939062 DOI: 10.1111/j.1740-8261.2003.tb00482.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
In humans, magnetic resonance (MR) imaging is the method of choice for the diagnosis of stress fractures. In this paper, bilateral stress fracture of the lateral condyle of the third metacarpal bone in a French trotter is described. Results of the radiographic, MR imaging, and histologic examinations are presented, with a focus on the MR signal abnormalities found. Based on this patient, the potential use of MR imaging for the diagnosis of stress fractures in horses is discussed.
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Affiliation(s)
- Jackie Tapprest
- UMR-INRA Biomécanique et pathologie locomotrice du cheval, Ecole Nationale Vétérinaire d'Alfort, CIRALE, Goustranville 14430, France
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9
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Abstract
REASONS FOR PERFORMING STUDY Tibial stress fractures are an important cause of lameness in the Thoroughbred racehorse. While it is recognised that these injuries can vary in clinical presentation and radiographic or scintigraphic appearance, little has been done to quantify lesion severity. By contrast the scintigraphic grading of tibial stress fractures in human athletes is widely reported and assists in the selection of appropriate management regimes. OBJECTIVES To determine the relationship between scintigraphic grade, clinical severity and radiographic appearance of tibial stress fractures. METHODS The current study involved the retrospective analysis of records from 42 Thoroughbreds with abnormal tibial scintigraphic activity. RESULTS There was a significant association between lesion site and scintigraphic grade and good correlation of scintigraphic scoring between investigators. No significant association was found between scintigraphic grade and either radiographic grade or degree of lameness. CONCLUSIONS The study confirmed that radiographic appearance is an unreliable measure of clinical severity or stage of progression of lesions. The scintigraphic grading system used in the study was not of use in defining stress fracture severity in the equine tibia. POTENTIAL RELEVANCE Despite this finding, there is clearly a need for prospective investigations to explore the potential for targeted management regimes for tibial injuries based on lesion site or clinical criteria.
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Affiliation(s)
- P H L Ramzan
- Beaufort Cottage Stables, High Street, Newmarket, Suffolk CB8 8JS, UK
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10
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Abstract
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.
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Abstract
OBJECTIVE To report a technique for, and outcome after, arthroscopic removal of dorsoproximal chip fractures of a proximal phalanx in standing horses. STUDY DESIGN Retrospective study. ANIMALS OR SAMPLE POPULATION A total of 104 horses, 1 to 13 years of age, with a dorsoproximal chip fracture of a proximal phalanx. METHODS Horses were restrained in standing stocks and sedated with intravenous xylazine, detomidine, or a combination of both drugs. Local analgesia was achieved with 2% mepivacaine administered intra-articularly and by subcutaneous infiltration in a crescent-shaped block dorsal to the fetlock. Sterile drapes were placed on the surgical field, and impervious drapes were used on the hoof and floor. Arthroscopic portals were created in the dorsal pouch of the metacarpophalangeal or metatarsophalangeal joints to remove chip fractures. Statistical analysis was performed on race records for all Thoroughbred racehorses and compared with previously published studies. Operative and hospitalization times were compared with those of the general hospital population, and risks associated with general anesthesia were examined. RESULTS No major operative or postoperative complications occurred. Ninety-one percent of racehorses raced after surgery with 78% returning to race at the same or higher level. CONCLUSION Standing arthroscopic surgery can be performed successfully to remove dorsoproximal chip fractures of the proximal phalanx. CLINICAL RELEVANCE Standing arthroscopic surgery is a valid alternative treatment for experienced surgeons to avoid the expense and potential risks associated with general anesthesia.
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Affiliation(s)
- Yvonne A Elce
- Department of Clinical Studies, New Bolton Center, University of Pennsylvania, 382 West Street Road, Kennett Square, PA 19348, USA
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12
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Ellis D. Fractures--a preventable hazard of racing thoroughbreds. Vet J 2002; 163:5-6. [PMID: 11749131 DOI: 10.1053/tvjl.2001.0609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Fractures are a common cause of loss among Thoroughbred racehorses. A large proportion of these injuries occurs in the absence of a specific traumatic event and show typical characteristics of stress fractures. The fractures show a high degree of consistency in their morphology; they frequently share the same locations as incomplete cracks and they are often associated with pre-existing pathology (periosteal and endosteal new bone formation and intracortical remodelling). Bone is able to adapt to changes in its mechanical environment. Studies of the Thoroughbred racehorse show modification of the geometric properties of the third metacarpal bone in response to training. These modifications are associated with reduced bone strains. Intense training before the adaptive response is completed and bone strain reduced increases the risk of fatigue damage. Fatigue of bone is associated with progressive microdamage, which is important in the pathogenesis of stress fractures. However, the biological repair mechanism of bone (remodelling) is also instrumental in the development of stress fractures. Horses exercised before bone repair is complete are likely to be at significantly greater risk of sustaining a catastrophic stress fracture. A number of key questions regarding the importance of microdamage, remodelling and training schedules in the prevention of stress fractures are addressed in this review.
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Affiliation(s)
- C M Riggs
- Oakey Veterinary Hospital, Oakey, Queensland, 4401, Australia.
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14
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Abstract
This paper addresses an anomaly which exists in the current literature regarding stress fractures. Analysis of the data on fatigue strength of bone samples in vitro would conclude that these fractures should never occur at the strain levels known to occur in vivo. This anomaly can be resolved by including in the analysis the effect of stressed volume, whereby larger volumes of material are expected to have worse fatigue properties. A Weibull analysis was used to predict the probability of failure, Pf; this was an upper-bound prediction because it did not include the effects of remodelling and adaptation. Combining this analysis with a finite element model of the human tibia, we predicted a Pf value of 21% after five weeks of strenuous exercise, which is comparable with reported incidences in military personnel. The high incidence of stress fractures in the cannon bone of racehorses could also be predicted (Pf = 62%, compared to 70% experimentally). The approach can be used to investigate the effect of variables in the exercise regime such as the distance run per day and the use of improved footwear. It can also predict the increased risk of stress fractures in elderly people. The results suggest certain simple rules which may be of clinical value in designing exercise regimes and in understanding the risk factors for this type of injury.
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Affiliation(s)
- D Taylor
- Mechanical Engineering Department, Trinity College, Ireland.
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15
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Colón JL, Bramlage LR, Hance SR, Embertson RM. Qualitative and quantitative documentation of the racing performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx osteochondral fractures (1986-1995). Equine Vet J 2000; 32:475-81. [PMID: 11093620 DOI: 10.2746/042516400777584640] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to examine the longevity of postoperative careers and quality of performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx (P1) osteochondral fractures. Six hundred and 59 dorsoproximal P1 chip fractures were removed arthroscopically from 574 joints in 461 horses presented for lameness or decreased performance attributed to the chip fractures. Radiological and arthroscopic examination revealed an average of 1.43 fragment sites/horse, 1.15 fragment sites/joint and 1.25 affected joints/horse. Eighty-nine percent of the horses (411/461) raced after surgery and 82% (377/461) did so at the same or higher class. Fifty horses did not race after surgery. Sixty-eight percent of the horses raced in a Stake or Allowance race postoperatively. Data, previously undocumented, establishes that the quantity and quality of performance is not diminished after arthroscopic treatment of dorsoproximal P1 fragmentation. Surgical removal of chip fractures is a means of preserving the economic value of an injured Thoroughbred, allowing a rapid and successful return to racing at the previous level of racing performance.
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Affiliation(s)
- J L Colón
- Rood & Riddle Equine Hospital, Lexington, Kentucky 40580, USA
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16
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Tomlin JL, Lawes TJ, Blunn GW, Goodship AE, Muir P. Fractographic examination of racing greyhound central (navicular) tarsal bone failure surfaces using scanning electron microscopy. Calcif Tissue Int 2000; 67:260-6. [PMID: 10954782 DOI: 10.1007/s002230001129] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The greyhound is a fatigue fracture model of a short distance running athlete. Greyhounds have a high incidence of central (navicular) tarsal bone (CTB) fractures, which are not associated with overt trauma. We wished to determine whether these fractures occur because of accumulation of fatigue microdamage. We hypothesized that bone from racing dogs would show site-specific microdamage accumulation, causing predisposition to structural failure. We performed a fractographic examination of failure surfaces from fractured bones using scanning electron microscopy and assessed microcracking observed at the failure surface using a visual analog scale. Branching arrays of microcracks were seen in failure surfaces of CTB and adjacent tarsal bones, suggestive of compressive fatigue failure. Branching arrays of microcracks were particularly prevalent in remodeled trabecular bone that had become compact. CTB fractures showed increased microdamage when compared with other in vivo fractures (adjacent tarsal bone and long bone fractures), and ex vivo tarsal fractures induced by monotonic loading (P < 0.02). It was concluded that greyhound racing and training often results in CTB structural failure, because of accumulation and coalescence of branching arrays of fatigue microcracks, the formation of which appears to be predisposed to adapted bone.
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MESH Headings
- Adaptation, Physiological
- Animals
- Calcaneus/injuries
- Calcaneus/ultrastructure
- Dog Diseases/diagnostic imaging
- Dog Diseases/pathology
- Dogs/injuries
- Fractals
- Fractures, Stress/diagnostic imaging
- Fractures, Stress/pathology
- Fractures, Stress/veterinary
- Microscopy, Electron, Scanning
- Radiography
- Stress, Mechanical
- Tarsus, Animal/diagnostic imaging
- Tarsus, Animal/injuries
- Tarsus, Animal/ultrastructure
- Weight-Bearing
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Affiliation(s)
- J L Tomlin
- The Royal Veterinary College, University of London, Dept. of Small Animal Medicine and Surgery, Hawkshead Lane, North Mymms, United Kingdom
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17
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Abstract
OBJECTIVE To compare microcrack density and length in the proximal and distal metaphyses of the humerus and radius in dogs. SAMPLE POPULATION Left humerus and radius from each of 10 dogs of medium to large size. PROCEDURE Metaphyseal specimens were bulk stained in 1% basic fuchsin in graded alcohols and embedded in methylmethacrylate. For quantification of fatigue-induced microscopic damage, transverse sections were prepared from proximal and distal metaphyseal regions, and length and density of microcracks were determined, using light microscopy. RESULTS Bone region, age, and body weight were not significantly associated with microcrack density or length. CONCLUSIONS AND CLINICAL RELEVANCE The hypothesis that fatigue-induced injury (increased microcrack density and length) caused by cyclic loading associated with daily activity is greater in bone regions prone to development of osteosarcoma was not supported by data from this study.
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Affiliation(s)
- P Muir
- Department of Small Animal Medicine and Surgery, The Royal Veterinary College, University of London, North Mymms, Hertfordshire, UK
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18
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Abstract
Greyhound central tarsal bone (CTB) from animals with (n = 11) and without CTB fatigue fracture (n = 15) was examined histologically for the presence, numerical density, and morphology of in vivo microdamage. Complete fracture of the right CTB is a common occurrence during dog racing, because this is the outside limb when running counterclockwise on a circular or oval track. The CTB consisted of both remodeled cortical bone and inner trabecular bone. Thickening and coalescence of trabeculae were observed, particularly dorsally and medially, causing reduction or elimination of the marrow void spaces. A band of tightly packed transverse osteons was also observed adjacent to the concave proximal joint surface. Typical linear microcracks were most often seen in remodeled cortical and trabecular bone and were often observed adjacent to vascular channels. In contrast, ultra-microcracking, represented by diffuse staining with basic fuchsin, was consistently observed in the plantar process around the attachment site for the plantar ligament complex. Dog status (fractured or intact) and side (left or right) both had a significant effect on microcrack density and microcrack surface density (p < 0.05). Microcrack density and microcrack surface density were increased in the right (fractured) CTB from greyhounds with CTB fracture. There was also a trend for side to have a significant effect on microcrack length, with microcrack lengths being higher in the right CTB of both intact and fractured dogs. These data support the general hypothesis that fatigue fracture occurs because of ongoing cyclic stresses after induction of reparative remodeling. Development of methods for biomechanical testing of small cuboidal bones should allow investigation of relationships between accumulation of loading cycles and bone weakening because of microdamage.
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Affiliation(s)
- P Muir
- Department of Small Animal Medicine and Surgery, The Royal Veterinary College, University of London, Hertfordshire, UK.
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Abstract
Thirty-six Thoroughbred racehorses that died at California racetracks between October 1993 and July 1994 were evaluated for stress fractures in the caudal portion of the thoracic and lumbosacral regions of the spine and the pelvis. The lumbosacral spine and pelvis were collected, debrided of soft tissues and examined visually for the presence of an incomplete fracture line and focal periosteal proliferation, characteristic of a stress fracture. Sixty-one per cent of specimens had evidence of stress fracture in the caudal portion of the thoracic and lumbosacral regions of the spine and the pelvis. Vertebral lamina stress fractures were found in 50% of specimens and were positively associated with the severity of dorsal spinous process impingement and overall severity of articular process degenerative changes. Pelvic stress fractures affected 28 % of specimens and occurred more frequently in older horses. Pelvic stress fractures were positively associated with the severity of lumbar transverse process impingement and several ilial articular surface degenerative changes. A high prevalence of vertebral and pelvic stress fractures was noted in this sample of Thoroughbred racehorses that died because of unrelated injuries. Vertebral and pelvic stress fractures need to be considered in the clinical evaluation of horses with back problems or hindlimb lameness. Undiagnosed stress fractures of the vertebrae or pelvis could be a significant cause of poor performance and lameness in Thoroughbred racehorses.
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Affiliation(s)
- K K Haussler
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis 95616, USA
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20
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Abstract
OBJECTIVE To describe incomplete oblique sagittal dorsal cortical fractures of the equine third metacarpal bone, their surgical repair, and subsequent performance of the horses. STUDY DESIGN Retrospective examination of medical records and racing performance. ANIMAL POPULATION Six Thoroughbred race horses, 2 to 4 years of age. METHODS Radiographic confirmation of all fractures preceded general anesthesia and surgical correction. Three fractures were treated by intracortical compression using screws placed in lag fashion, and five fractures were treated by osteostixis. Race records were reviewed for each horse to determine performance after surgery. RESULTS Fractures were best observed on palmarodorsal radiographic projections. Three horses treated by intracortical compression returned to racing, but fracture recurred in one horse and was treated by osteostixis. This horse and the other three horses treated by osteostixis raced after surgery. CONCLUSIONS Horses with incomplete oblique sagittal fractures of the dorsal cortex of the third metacarpal bone can race after surgical management of the fracture by screws placed in lag fashion or osteostixis. The authors' preferred surgical procedure for managing this fracture is osteostixis. CLINICAL RELEVANCE Palmarodorsal radiographic projections of the third metacarpal bone are recommended in young Thoroughbred race horses suspected of having dorsal metacarpal stress fractures.
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Affiliation(s)
- B C Watt
- Illinois Equine Hospital and Clinic, Naperville, USA
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21
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Hardie EM, Ramirez O, Clary EM, Kornegay JN, Correa MT, Feimster RA, Robertson ER. Abnormalities of the thoracic bellows: stress fractures of the ribs and hiatal hernia. Vet Med (Auckl) 1998; 12:279-87. [PMID: 9686388 DOI: 10.1111/j.1939-1676.1998.tb02123.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The thoracic bellows mechanism consists of the rib cage and the diaphragm. The purpose of this study was to determine if nontraumatically acquired lesions of the bellows were secondary to underlying disease. Abnormalities of the bellows, specifically stress fractures of the ribs and hiatal hernia, were found in 21 dogs and cats with underlying cardiopulmonary disease, neuromuscular disease, or metabolic disease. A case-control study of Bulldogs demonstrated that hiatal hernia was associated with the more severe manifestations of brachycephalic syndrome. Stress fractures occurred mostly in females and in cats, and involved multiple ribs. Fractures were usually related to severe respiratory effort, but also occurred in association with metabolic disease. Hiatal hernia was also associated with severe respiratory effort, but may be exacerbated if a neuromuscular disorder affecting the diaphragm is present. Abnormalities of the thoracic bellows, such as rib stress fractures and hiatal hernia, may be signs of underlying disease, rather than being primary causes of disease.
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Affiliation(s)
- E M Hardie
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA.
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22
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Rhoads WS, Cox JH. What is your diagnosis? Compression fracture of the 12th thoracic vertebra. J Am Vet Med Assoc 1997; 210:755-6. [PMID: 9074674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- W S Rhoads
- Department of Surgery and Medicine, College of Veterinary Medicine, Kansas State University, Manhattan 66506, USA
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Affiliation(s)
- W J Hornof
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis 95616, USA
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24
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Abstract
We studied remodeling and microcrack damage in specimens of Thoroughbred racehorse third metacarpal bone that had been subjected to monotonic or fatigue failure. We asked three questions. What effects does mechanical loading have on histologically observable microcrack damage? Are there regional variations in remodeling of the equine cannon bone, and do these variations correlate with mechanical properties? To what extent are remodeling and microcrack damage age-dependent? Machined beams from the medial, lateral, and dorsal cortices were loaded to fracture in four-point bending monotonically, or cyclically at a load initially producing 10,000 microstrain. Specimens were then bulk-stained in basic fuchsin, and cross sections were prepared from loaded and load-free regions of each beam. Current and past remodeling, porosity, and microcrack density and length were determined histomorphometrically. Strained and unstained microcracks were observed. Unstained cracks were associated with regions of woven bone and appeared to be damaged Sharpey's fibers. Their density (approximately 30/mm2) did not increase after failure, but their length (approximately 25 microns) did, especially near the surfaces of the beam. Stained cracks were wider and longer than unstained cracks and were located primarily near the fracture surface and on the compressed side of the beam. Stained cracks after failure were more numerous in those beams having a higher elastic modulus, a shorter fatigue life, or greater deformation at failure. The extent of past remodeling increased with age, especially in the medial region; the rate of current remodeling generally declined with age, but not in the dorsal region, which has the best fatigue resistance. In summary, while remodeling varied with age and region, its effects on bone structure did not appear to influence microdamage. Basic fuchsin staining of damage in fractured equine bone was independent of age and region and confined to near the fracture surfaces. Distributed microdamage consisted only of what appeared to be subtle disruptions of Sharpey's fibers.
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Affiliation(s)
- R B Martin
- Orthopaedic Research Laboratories, School of Medicine, University of California at Davis, USA
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25
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Pilsworth RC, Riggs CM. The motto of necessity: imaging modalities for orthopaedic prognosis. Equine Vet J 1996; 28:341-3. [PMID: 8894529 DOI: 10.1111/j.2042-3306.1996.tb03102.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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26
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Ruggles AJ, Moore RM, Bertone AL, Schneider RK, Bailey MQ. Tibial stress fractures in racing standardbreds: 13 cases (1989-1993). J Am Vet Med Assoc 1996; 209:634-7. [PMID: 8755986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To determine clinical signs, radiographic and scintigraphic findings, and performance outcome of racing Standardbreds with tibial stress fractures. DESIGN Retrospective case series. ANIMALS 13 racing Standardbreds with tibial stress fractures. PROCEDURE Information concerning clinical signs, diagnostic evaluation, and recommendations was obtained by review of the medical records. Performance information before and after diagnosis of the fracture was collected from racing records, and follow-up information was obtained from the owners or trainers by use of a telephone questionnaire. RESULTS Horses with tibial stress fractures were moderately lame, and diagnosis was made by nuclear scintigraphy and radiography. Fractures were more likely to occur in 2-year-old horses than in older horses. The fracture location was unique for Standardbreds; 11 of 13 developed stress fractures in the mid-diaphysis of the tibia, whereas fractures in Thoroughbreds are usually in the proximal caudal or caudolateral cortex. Fractures occurred in young horses that had raced or were in advanced race training. All horses were treated with rest alone, and 10 of 13 horses raced after injury. The horses that raced after injury were able to return to a level of performance that was equal to or better than the level raced before injury. 8 of 10 horses established a lifetime-best winning time after injury. CLINICAL IMPLICATIONS Tibial stress fractures are a cause of lameness in young racing Standardbreds. Diagnosis is aided by nuclear scintigraphy. The prognosis for return to previous level of performance after a tibial stress fracture is good.
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Affiliation(s)
- A J Ruggles
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, Columbus 43210-1089, USA
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Abstract
This is the first in a series of experiments to study the fatigue properties of equine cannon (third metacarpal) bone specimens from Thoroughbred racehorses. Monotonic and fatigue tests to failure were performed in four-point bending on diaphyseal specimens in a 37 degrees C saline bath to answer three initial questions. (a) Will a linear variable differential transducer yield the same elastic modulus as strain gauges? (b) Will fatigue results depend on whether the periosteal or endosteal side of the beam is in tension? (c) Are there regional variations in the monotonic and fatigue properties of the cannon bone midshaft? Eighteen left-right pairs of specimens from six horses were used. One beam of each pair was fitted with strain gauges. Fatigue tests were conducted on 24 specimens under load control at 2 Hz; an initial range of 0-10,000 microstrain was used so as to produce failure in a reasonable period of time. There were no left-right differences in the fatigue or monotonic properties, and the presence of a gauge had no effect on modulus measured by a linear variable differential transducer. However, gauge-measured moduli were about 1 GPa less than transducer-measured values. Fatigue life was independent of which side of the beam was in tension, and there were significant variations in mechanical properties around the cortex. The lateral region was stiffer than the dorsal region but the latter had a longer fatigue life. The fixed cylindrical supports used in this experiment eventually produced slight wear grooves, causing artifactual stiffening at the end of the load cycle in some specimens. A second experiment using roller supports confirmed the reason for this stiffening. It also showed that fatigue life was shorter when roller supports were used but regional differences were similar.
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Affiliation(s)
- V A Gibson
- Orthopaedic Research Laboratory, School of Medicine, University of California at Davis, USA
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28
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Kotz D. Scanning the animal world. J Nucl Med 1995; 36:16N, 35N-36N. [PMID: 7699433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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29
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Frankeny RL, Johnson PJ, Messer NT, Keegan KG, Corwin LA. Bilateral tibial metaphyseal stress fractures associated with physitis in a foal. J Am Vet Med Assoc 1994; 205:76-8. [PMID: 7928554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A 7-month-old Appaloosa foal had bilateral hind limb lameness and was unable to rise from recumbency without assistance. Lameness could be exacerbated by tarsal flexion and a firm swelling at the distomedial aspect of the tibias was associated with a marked pain response when palpated. Radiography revealed enlargement of the distal tibial metaphysis physis (compared with normal), and radiolucent fissure lines extending proximally from the physis into the metaphysis at its medial aspect. Treatment included rest and dietary adjustment. Although clinical signs initially resolved following treatment, the problem recurred when the foal was 14 months old. Further treatment included 7 months of pasture rest without forced exercise, after which the foal was reported to be clinically normal.
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Affiliation(s)
- R L Frankeny
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia 65211
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30
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Peloso JG, Watkins JP, Keele SR, Morris EL. Bilateral stress fractures of the tibia in a racing American quarter horse. J Am Vet Med Assoc 1993; 203:801-5. [PMID: 8226232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- J G Peloso
- Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station 77843-4475
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31
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Pleasant RS, Baker GJ, Muhlbauer MC, Foreman JH, Boero MJ. Stress reactions and stress fractures of the proximal palmar aspect of the third metacarpal bone in horses: 58 cases (1980-1990). J Am Vet Med Assoc 1992; 201:1918-23. [PMID: 1483918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The case records, radiographs, and nuclear bone scans of 58 horses with stress reactions or stress fractures of the proximal palmar aspect of the third metacarpal bone (MC3) were reviewed. There were 47 Standardbreds, 4 Quarter Horses, 3 Thoroughbreds, 2 Arabians, 1 Oldenburg, and 1 Pony of America. Fifty-six of the horses were racehorses or performance horses. The mean and median ages of affected horses were 4 and 3 years, respectively. Lameness ranged from mild to severe. Physical findings were usually subtle and included signs of pain on deep palpation of the proximal palmar aspect of MC3 and slight effusion of the middle carpal joint in some cases. Lameness was commonly improved by high palmar and palmar metacarpal nerve blocks or anesthesia of the middle carpal joint. Fifty-three horses had higher than normal radiopharmaceutical uptake in the proximal palmar aspect of MC3 in the left or right limb. The other 5 horses had higher than normal radiopharmaceutical uptake bilaterally. Fifty-six of the 63 limbs with abnormal bone scans also had abnormal radiographs. Treatment consisted of a variable period of rest (1 to 6 months). Healing was best assessed by follow-up bone scans. Of the 45 horses for which follow-up information was adequate, 29 (64%) returned to their previous level of performance.
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Affiliation(s)
- R S Pleasant
- Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana 61801
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Stover SM, Johnson BJ, Daft BM, Read DH, Anderson M, Barr BC, Kinde H, Moore J, Stoltz J, Ardans AA. An association between complete and incomplete stress fractures of the humerus in racehorses. Equine Vet J 1992; 24:260-3. [PMID: 1499531 DOI: 10.1111/j.2042-3306.1992.tb02831.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
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.
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Affiliation(s)
- S M Stover
- Department of Anatomy, School of Veterinary Medicine, University of California, Davis 95616-8732
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Cervantes C, Madison JB, Ackerman N, Reed WO. Surgical treatment of dorsal cortical fractures of the third metacarpal bone in thoroughbred racehorses: 53 cases (1985-1989). J Am Vet Med Assoc 1992; 200:1997-2000. [PMID: 1639714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Between January 1985 and May 1989, 53 Thoroughbred horses (mean age 3.2 years) were surgically treated for dorsal cortical fractures of the third metacarpal bone (MC III). All horses were treated with cortical drilling through the fracture line (osteostixis). Diagnosis of the fractures was confirmed by xeroradiography. Lifetime racing records were obtained for all horses. Forty-seven horses returned to racing after surgery (89%). The mean time between surgery and the first race was 6.8 months. Horses had a mean of 10.9 starts before surgery and 16.1 starts after surgery. The mean earnings per start before surgery was $6,459 and after surgery was $5,685. Of the 47 horses that raced after surgery, 70% raced at the same class or improved. Complications related to surgery were seen in 10 horses. Two horses had a second fracture of MC III at the same site, and were again treated by osteostixis, after which both horses returned to competition. Fractured drill bits were left in the MC III of 4 horses. One of these horses had catastrophic failure of MC III. Two horses developed subcutaneous infections and 2 horses had catastrophic failure of MC III in the surgically treated limb. Osteostixis appears to be an effective treatment for returning horses affected with dorsal cortical fractures to racing.
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Affiliation(s)
- C Cervantes
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610
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Abstract
The results of 31 intracortical dorsal metacarpal stress fractures in 28 horses following unicortical osteostixis were reviewed. The incidence was predominately in the middle third of the lateral aspect of the left metacarpus, and males were affected more commonly. Approximately half of the surgical procedures were performed with the horse in the standing position. The mean times to return to training and racing were 4.25 and 6.9 months respectively. There was no correlation between time taken to return to racing and position of surgery. Complications experienced included lack of suture removal and one case with a seroma.
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Affiliation(s)
- E A Hanie
- Marion DuPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine, Leesburg 22075, USA
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35
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Abstract
The North American Thoroughbred racehorse was chosen as a model to study the pathogenesis of fatigue failure of bone. This species has a high incidence of spontaneous fatigue failure of bone (bucked shins) during its early training. In vivo strain gauge studies of the third metacarpal bone of four young racehorses running at racing speeds showed high principal compressive strains [-4,841 +/- 572 (SD) microstrain] while two older horses had lower principal compressive strains (-3,317 microstrain measured at racing speed, -3,250 microstrain extrapolated from a slower speed run). Previously reported inertial property measurements of the third metacarpal bone were related to the difference in bone strains seen in young and older horses. The high strains on the surface of the third metacarpal bone associated with young horses in training may lead to high strain, low cycle fatigue. The changing shape of the third metacarpal bone during maturation may be consistent with the lower strains recorded during high speed exercise in the older animals. This phenomenon may allow for the accumulation of additional strain cycles in older animals before failure occurs.
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Affiliation(s)
- D M Nunamaker
- Comparative Orthopaedic Research Laboratory, University of Pennsylvania School of Veterinary Medicine, Kennett Square 19348
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36
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Abstract
Eleven horses with acute or chronic incomplete cortical fractures of the left or right third metacarpal bone (McIII) were treated with surgical puncture (osteostixis). The fractures were diagnosed by physical examination and radiography. Four to eight holes, 2.7 or 3.5 mm in diameter, were drilled in the fractured bone. Radiographically, the fractures were healed by month 3, and the drill holes were inapparent by month 7. Nine horses (82%) returned to race competition, and two horses were retired, one the result of a surgical complication. The mean time between surgery and the first race was 9.4 months. None of the bones refractured within 24 months of surgery. Osteostixis was not technically difficult and a second operation for implant removal was not necessary.
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Affiliation(s)
- T E Specht
- Department of Surgical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610-0136
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Dallman MJ, Martin RA, Self BP, Grant JW. Rotational strength of double-pinning techniques in repair of transverse fractures in femurs of dogs. Am J Vet Res 1990; 51:123-7. [PMID: 2301811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Transverse midshaft fractures of femurs from freshly euthanatized dogs were stabilized by means of 6 methods: (1) 3.5-mm bone plate and screws, (2) single intramedullary pin, (3) double intramedullary pins retrograded proximally and driven distally to the level of the femoral trochlea, (4) double intramedullary pins retrograded distally and driven proximally into the trochanteric region, (5) double intramedullary pinning in Rush pin fashion, and (6) multiple intramedullary pinning that filled the medullary cavity at the fracture site. All bones were subjected to torsional stress. The measured strain was converted to forces of torque and correlated with bone diameter to normalize the data. The forces of torque from each fixation technique were compared with each other and with the mean torque force necessary to fracture intact femurs. Torsional shear applied to plated femurs resulted in failure at a mean level of 33.8% of the calculated theoretic moment. Torsional forces were concentrated at one end of the plate and catastrophically failed at that point, whereas the fracture site remained rigidly fixed. There was no significant difference in the initial moment of torsional failure between the single intramedullary pin technique (0.05 Nm) and the double-pinning techniques (0.03 to 0.04 Nm). The multiple-pinning technique was 1.8 to 3 times as effective in resisting rotational forces, compared with the other pinning techniques, but not significantly so.
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Affiliation(s)
- M J Dallman
- Department of Small Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg
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38
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Abstract
Five horses, all two year old Thoroughbreds, presented with acute onset hindlimb lameness following moderate to fast exercise. The use of a hand-held scintillation detector after Tc99 MDP injection greatly aided the diagnosis of tibial stress fractures in these horses. Radiological findings were subtle, involving only periosteal new bone and callus at the fracture site. In two cases this took several weeks to develop but in three others was present at the onset of lameness, indicating insidious pre-fracture bone pathology. The site of the most obvious radiological signs was constant in all five cases, being the proximal lateral tibia some 8 to 9 cm from the femoro-tibial joint surface. The diagnosis of five cases of tibial fracture in one racing season suggests that this condition has been underdiagnosed in the past in this clinic, prior to the availability of bone scanning.
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