Surgical versus conservative management of osteochondrosis

Methodological approaches to assessing the genetic predisposition of osteochondrosis of the tarsocrural joint in the Pura Raza Española horses

Osteochondrosis (OC) is a developmental orthopaedic disease of significant concern in numerous sport horse breeds, with significant international relevance. Using digital radiographs, we assessed the occurrence of hock (tarsocrural joint) OC in 3 048 Pura Raza Española (PRE) horses which took part in a morpho-functional test, in three specific locations in the tarsus limbs: the Distal Intermediate Ridge of the Tibia (DIRT), the lateral trochlear ridges of the talus (LTT), and the medial trochlear ridges of the talus (MTT). An incidence rate of 13.3% was found for hock OC in the analysed sample, with the highest incidence rate observed in DIRT (10.0%) and the lowest in MTT (0.2%). Estimates of genetic predisposition to hock OC were carried out using three genetic approaches: 1a) a binomial threshold model based on the presence or absence of OC, 1b) a multinomial threshold model, on a scale from 0 (absence) to 3 (maximum), and 2) a linear model. The effects considered in the models included sex, genetic origin and stud class. All the analyses were based on the Bayesian inference methodology, using the THRGIBBS3F90 software. The binomial threshold model yielded the most suitable results, with an estimated heritability for Overall hock OC of 0.71 ± 0.055 on the underlying scale (0.53 on the observed scale), ranging in different locations from 0.48 ± 0.087 (LTT) to 0.66 ± 0.063 (DIRT) on the underlying scale (0.10 and 0.38 on the observed scale, respectively). The highest significative genetic correlation was observed between Overall and DIRT (0.97) for approach 1a, and the lowest significant genetic correlation was between Overall and LTT (0.49), for approach 2. This study contributes valuable insights into the genetic predisposition towards, as well as for the potential for selective breeding against, hock OC in PRE horses, and provides a basis for future research and breeding programmes aimed at minimising the occurrence of hock OC and promoting the overall health of this breed.

Radiological properties of nano-hydroxyapatite compared to natural equine hydroxyapatite quantified using dual-energy CT and high-field MR

In equine medicine, assisted bone regeneration, including use of biomaterial substitutes like hydroxyapatite (HAP), is crucial for addressing bone defects. To follow-up on the outcome of HAP-based bone defect treatment, the advancement in quantified diagnostic imaging protocols is needed. This study aimed to quantify and compare the radiological properties of the HAP graft and natural equine bone using Magnetic Resonance (MR) and Computed Tomography (CT), both Single (SECT) and Dual Energy (DECT). SECT and DECT, allow for the differentiation of three HAP grain sizes, by progressive increase in relative density (RD). SECT, DECT, and MR enable the differentiation between natural cortical bone and synthetic HAP graft by augmentation in Effective Z and material density (MD) in HAP/Water, Calcium/Water, and Water/Calcium reconstructions, alongside the reduction in T2 relaxation time. The proposed quantification provided valuable radiological insights into the composition of HAP grafts, which may be useful in follow-up bone defect treatment.

Racing Performance and Sale Result in 145 Thoroughbreds after Arthroscopic Removal of Osteochondral Fragments from the Lateral Femoral Trochlear Ridge as a Yearling (2012-2015)

OBJECTIVES

 The lateral trochlear ridge (LTR) of the femur is the most common predilection site for osteochondritis dissecans (OCD) in the equine stifle. The objective was to investigate the relationship between lesion size, racing performance, and sale result of Thoroughbreds with LTR OCD following arthroscopic removal as a yearling.

METHODS

 In this retrospective study, medical records of 145 Thoroughbreds from one equine hospital that underwent surgery for LTR OCD were reviewed; the length and depth of the lesions were measured on preoperative radiographs. Horses were allocated to group S if they were presented to a public yearling sale post-surgery, and horses in group NS were not. Each horse from group S was matched with two control horses from the same sale (group C). Influence of lesion size on racing performance and sale result was analyzed. Racing performance and sale results were compared between different categories of OCD lesion sizes and between the groups.

RESULTS

 Lesion length and depth did not affect racing performance and did not differ between group S and group NS. However, group S did perform significantly better than group NS. When comparing groups S and C, there were no significant differences in racing performance and sale result.

CONCLUSION

 Thoroughbreds that had arthroscopic surgery for LTR OCD as a yearling and were presented on a public yearling sale performed comparable to Thoroughbreds that showed similar potential as a yearling. Sale result is not significantly affected in our study.

Effects of intra-articular administration of hyaluronic acid or platelet-rich plasma as a complementary treatment to arthroscopy in horses with osteochondritis dissecans

Although arthroscopy is the treatment of choice for horses with osteochondritis dissecans (OCD), it is not yet known whether intra-articular therapies in the postoperative period can bring any benefit to the recovery of these animals. This study evaluated the effects of the intra-articular application of platelet-rich plasma (PRP), hyaluronic acid (HA) or lactated Ringer's solution (LR) in horses with OCD undergoing arthroscopy. Eighteen male and female Brazilian Sport horses aged between 2 and 6 years were evaluated. All animals presented OCD fragments in the middle crest of the tibia. Ten days after surgery, animals were randomly distributed into three groups and received intra-articular application of PRP (n = 6), HA (n = 6), or LR (control group, n = 6). Clinical, radiographic, ultrasound and synovial fluid evaluations were performed on the day of surgery and after 10, 30 and 60 days. An increase in the thickness of the joint capsule was observed 30 days after surgery in the three groups evaluated. In the control group, there was significant improvement in the flexion test 30 and 60 days after surgery, and in the PRP group, there was worsening of this parameter in the same evaluations. In the control group, there was a reduction in the degree of synovial effusion, and in the PRP and HA groups, there was increased effusion. There was a significant increase in the number of leukocytes in the HA group. Intra-articular use of PRP or HA ten days after arthroscopy did not promote positive effects on the recovery of horses with OCD.

Racing performance of juvenile Thoroughbreds with femoropatellar osteochondrosis at auction: A retrospective case-control study

BACKGROUND

Osteochondrosis dissecans (OCD) is common in the femoropatellar joint in Thoroughbred yearlings for sale at auction and there is no consensus on the effect on racing outcomes.

OBJECTIVES

Describe femoropatellar OCD in juvenile Thoroughbreds and compare the racing performance of affected Thoroughbred horses to siblings and unaffected horses from the same sale.

STUDY DESIGN

Retrospective case-control study of juvenile horses born 2010-2016.

METHODS

Radiographic reports from 27 Thoroughbred auctions of weanling (5-11 months of age) and yearling (12-22 months of age) horses were reviewed to identify femoropatellar OCD. Age and sex of cases and controls were obtained from the sales catalogue. Racing performance was obtained from an online database. Correlation between lesion characteristics and racing performance were assessed using Pearson and Spearman correlations for continuous and ordinal/categorical variables respectively. Racing performance was compared between cases and sibling controls and age- and sex-matched sale number controls from the same sale with Poisson distribution and log link. Significance level of alpha = 0.05 was used.

RESULTS

Femoropatellar OCD was identified in 429 horses with North American race records. OCD was present on 519 lateral trochlear ridges and 54 medial trochlear ridges. There were more males in the case group (70%) than in the sibling control group (47%). Case racing performance was compared to 1042 sibling and 757 hip controls. There were significant but small decreases in racing metrics of cases and increases in males for years raced, total starts, starts for 2-5 years of age, total placings, and placings at 2-4 years of age. Analysis of specific lesion metrics revealed weak correlations for performance outcomes (positive and negative) resulting in an inability to draw firm conclusions.

MAIN LIMITATIONS

Retrospective study where case management was unknown.

CONCLUSIONS

Femoropatellar OCD in juvenile Thoroughbreds for sale at auction decreases some racing outcomes.

Evaluation of cartilage injury in horses with osteochondral fragments in the metacarpo-/metatarsophalangeal joint: A study on 823 arthroscopies

BACKGROUND

Osteochondral fragment removal is commonly performed but there are little scientific data supporting this procedure in the absence of clinical signs. More information is needed to facilitate clinical decision-making regarding fragment removal of the metacarpo-/metatarsophalangeal joint.

OBJECTIVES

To assess prevalence of cartilage injury in the equine metacarpo-/metatarsophalangeal joint and its association to fragment size, location, age and lameness.

STUDY DESIGN

Retrospective observational study.

METHODS

Clinical records, including radiographs of 823 metacarpo-/metatarsophalangeal joints (640 horses) that underwent arthroscopic fragment removal, were reviewed. Fragment size, intra-articular fragment location and cartilage injury score were recorded. Presence of synovitis was retrospectively evaluated in 157 joints. Kruskal-Wallis and Mann-Whitney tests were used for group comparisons, and Dunn's post hoc test was applied for multiple comparisons. Linear regression analysis was used to assess strength of association between age and mean cartilage score. Univariable regression analysis was performed and variables with p < 0.2 were used in the final mixed-effects multivariable model to which backwards stepwise selection was applied. Significance level was p < 0.05.

RESULTS

Cartilage injury was present in 28.8% (95% CI = 25.8-32.0) of joints. Lameness was not associated with fragment location or fragment size. Fragment size was not associated with cartilage injury. Age (OR = 1.35, 95% CI = 1.22-1.48, p < 0.001) and lameness (OR = 5.03, 95% CI = 2.27-11.68, p < 0.001) were associated with cartilage injury as well as fragment location (palmar/plantar, OR = 0.22, 95% CI = 0.13-0.38, p < 0.001), with dorsal fragments being more likely to be associated with cartilage lesions than palmar/plantar fragments. There was a significant association between age and mean cartilage score (b = 0.18, 95% CI = 0.14-0.22, p < 0.001).

MAIN LIMITATIONS

The series included a heterogenous group of horses of different breed, sex, age and use. Data were collected retrospectively and could, in parts, not be fully evaluated.

CONCLUSIONS

Early fragment removal, especially in joints with dorsal fragmentation, can be beneficial to avoid future cartilage injuries in equine athletes.

Arthroscopic removal of osteochondral fragments of the cervical articular process joints in three horses

OBJECTIVE

To report arthroscopic osteochondral fragment removal from the equine cervical spine articular process joints (APJs) including long-term follow-up.

STUDY DESIGN

Case series.

ANIMALS

Three Warmblood horses with forelimb lameness and/or reduced range of motion of the cervical spine with osteochondral fragments between the cervical vertebrae C5 /C6 or C6 /C7 .

METHOD

Arthroscopy of the APJs of C5 /C6 and C6 /C7 was performed under general anesthesia. Following endoscopic evaluation of the joints, osteochondral fragments were removed using a rongeur.

RESULTS

All horses recovered from anesthesia with no anesthetic or minor postanesthetic complications. One horse needed a second procedure for fragment removal. Fourteen to 31 months post-surgery the horses were sound for their intended use and neurological examination revealed no abnormalities.

CONCLUSION

Arthroscopic removal of osteochondral fragments can be performed safely in the equine cervical APJs of C5 /C6 and C6 /C7 resulting in a favorable long-term outcome.

CLINICAL SIGNIFICANCE

Arthroscopic removal is a valid option for horses showing clinical signs that can be attributed to osteochondral fragments in the APJs of the neck.

Evaluation of the appearance of osteochondrosis lesions by two radiographic examinations in sport horses aged from 12 to 36 months

Osteochondrosis is a developmental orthopedic disease characterized by a defect of enchondral ossification. This pathological condition develops and evolves during growth and is influenced by various factors, in particular genetic and environmental. However, little research has been conducted on the dynamic of this condition in horses after the age of 12 months. The retrospective study presented here investigates changes in osteochondrosis lesions through two standardized radiographic examinations carried out on young Walloon sport horses after one year of age (mean age at first and second examination was 407 (±41) and 680 (±117) days respectively). Each examination, analyzed independently by three veterinarians, included latero-medial views of the fetlocks, hocks, stifles, plantarolateral-dorsomedial hocks view and additional radiograph if the operator deemed it necessary. Each joint site was graded as healthy, osteochondrosis (OC) or osteochondrosis dissecans (OCD) affected. A group of 58 horses was studied, among them 20 presented one or more osteochondrosis lesions for a total of 36 lesions present during at least one examination. In this population, 4 animals (6.9%) presented osteochondrosis during only one examination (2 at the first examination and 2 at the second one). Moreover, it was possible to demonstrate the appearance, disappearance and more generally the evolution of 9/36 lesions (25%) within the different joints. The results of the study suggest that, although substantial main limitations, osteochondrosis lesions can evolve after the age of 12 months in sport horses. Knowing this is useful in helping to decide the appropriate radiographic diagnosis timing and management.

Osteochondritis dissecans (OCD) in Horses - Molecular Background of its Pathogenesis and Perspectives for Progenitor Stem Cell Therapy

Osteochondrosis (osteochondrosis dissecans; OCD) is a disease syndrome of growing cartilage related to different clinical entities such as epiphysitis, subchondral cysts and angular carpal deformities, which occurs in growing animals of all species, including horses. Nowadays, these disorders are affecting increasing numbers of young horses worldwide. As a complex multifactorial disease, OCD is initiated when failure in cartilage canals because of existing ischemia, chondrocyte biogenesis impairment as well as biochemical and genetic disruptions occur. Recently, particular attention have been accorded to the definition of possible relations between OCD and some metabolic disorders; in this way, implication of mitochondrial dysfunctions, endoplasmic reticulum disruptions, oxidative stress or endocrinological affections are among the most considered axes for future researches. As one of the most frequent cause of impaired orthopaedic potential, which may result in a sharp decrease in athletic performances of the affected animals, and lead to the occurrence of complications such as joint fragility and laminitis, OCD remains as one of the primary causes of considerable economic losses in all sections of the equine industry. It would therefore be important to provide more information on the exact pathophysiological mechanism(s) underlying early OC(D) lesions, in order to implement innovative strategies involving the use of progenitor stem cells, which are considered nowadays as a promising approach to regenerative medicine, with the potential to treat numerous orthopaedic disorders, including osteo-degenerative diseases, for prevention and reduction of incidence of the disease, not only in horses, but also in human medicine, as the equine model is already widely accepted by the scientific community and approved by the FDA, for the research and application of cellular therapies in the treatment of human conditions.

Differences between horse selection based on two forms of osteochondrosis in fetlock

Horses lose potential opportunities because of health problems. Available breeding strategies are not effective enough, probably also because of the different definition used and its genetic usefulness. The aim of the study was to compare the genetic background estimated by the genome-wide association study (GWAS) for osteochondrosis using two different scaling osteochondrosis (OC)/healthy and osteochondrosis dissecans (OCD)/healthy systems for evaluating the disease status of investigated fetlock joints. Two hundred one Warmblood horses trained for performance tests (87 stallions and 114 mares) were phenotyped and genotyped. Four fetlock x-ray images per horse were collected using the RTG Girth HF 80 and Vet Scan ray 3600. The DNA of each horse was genotyped using the BeadChip 70K. To identify SNPs that significantly affect the probability of osteochondrosis, two different methods were applied: the Cochran-Armitage test based on an additive mode of inheritance and logistic regression. The genetic background for osteochondrosis, expressed in the number of SNPs found with significant associations with osteochondrosis, was higher by evaluation in the scale of OCD/healthy horses (16 SNPs on several chromosomes mainly on the ECA1 and ECA10) than OC/healthy (2 SNPs on the ECA15 and one SNP on the ECA10). Detailed definition of osteochondrosis is needed in breeding and in veterinary practice. The genetic background for osteochondrosis and osteochondrosis dissecans seems not the same. Suggestive SNPs could be the candidate markers for osteochondrosis but should be checked on a larger population before usage.

Osteochondritis dissecans-like lesions of the occipital condyle and cervical articular process joints in a Saddlebred colt horse

Background

Osteochondritis dissecans (OCD) is a sequela to osteochondrosis, whereby the cartilage superficial to the site of osteochondrosis fractures and gives rise to osteochondral fragments in the affected joint. In this case, both the radiological and computed tomography findings were supportive of classical severe OCD but the histologic findings were not supportive of the diagnosis of OCD.

Case presentation

A 1 year and 6 months old, Saddlebred, colt was presented for evaluation of chronic cervical pain. Standing laterolateral radiographs revealed an osteochondral fragment with corresponding irregular subchondral bone defect at one of the occipital condyle. Computed tomography confirmed the presence of osteochondral fragments at the left occipital condyle and several articular process joints of the cervical spine, with associated subchondral bone defects and sclerosis, suggestive of OCD. However, the lack of ischemic chondronecrosis microscopically was not supportive of a histologic diagnosis of OCD. Therefore, the term ‘OCD-like lesions’ was deemed most appropriate for these cervical lesions.

Conclusion

In the event where imaging features were characteristics of OCD but lack of histologic evidence of ischemic chondronecrosis, the term ‘OCD-like lesion’ is deemed most appropriate.

Cartilage defect repair in horses: Current strategies and recent developments in regenerative medicine of the equine joint with emphasis on the surgical approach

Chondral and osteochondral lesions due to injury or other pathology are highly prevalent conditions in horses (and humans) and commonly result in the development of osteoarthritis and progression of joint deterioration. Regenerative medicine of articular cartilage is an emerging clinical treatment option for patients with articular cartilage injury or disease. Functional articular cartilage restoration, however, remains a major challenge, but the field is progressing rapidly and there is an increasing body of supportive clinical and scientific evidence. This review gives an overview of the established and emerging surgical techniques employed for cartilage repair in horses. Through a growing insight in surgical cartilage repair possibilities, surgeons might be more stimulated to explore novel techniques in a clinical setting.

Musculoskeletal Pathology

The current understanding of pathology as it relates to common diseases of the equine musculoskeletal system is reviewed. Conditions are organized under the fundamental categories of developmental, exercise-induced, infectious, and miscellaneous pathology. The overview of developmental pathology incorporates the new classification system of juvenile osteochondral conditions. Discussion of exercise-induced pathology emphasizes increased understanding of the contribution of cumulative microdamage caused by repetitive cyclic loading. Miscellaneous musculoskeletal pathology focuses on laminitis, which current knowledge indicates should be regarded as a clinical syndrome with a variety of possible distinct mechanisms of structural failure that are outlined in this overview.

Short- and long-term racing performance of Standardbred pacers and trotters after early surgical intervention for tarsal osteochondrosis

REASONS FOR PERFORMING STUDY

Osteochondrosis (OC) is commonly diagnosed in young Standardbred racehorses but its effect on performance when surgically treated at a young age is still incompletely understood. This is especially true for Standardbred pacers, which are underrepresented in the existing literature.

OBJECTIVE

To characterise the short- (2-year-old) and long-term (through 5-year-old) racing performance in Standardbred pacers and trotters after early surgical intervention (<17 months of age) for tarsal OC.

STUDY DESIGN

Retrospective clinical study.

METHODS

The study population consisted of related, age-matched Standardbred racehorses (n = 278; 151 pacers, 127 trotters) with (n = 133) or without (n = 145) one or more tarsal OC lesions. All OC-affected horses were treated surgically prior to being sold as yearlings. Data obtained from publicly available race records for each horse included starts, wins, finishes in the top 3 (win, place or show), earnings and fastest time. Comparisons between OC-affected and unaffected horses were made for the entire population and within gaits. A smaller related population (n = 94) had these performance measures evaluated for their 2-5-year-old racing seasons.

RESULTS

Osteochondrosis status was associated with few performance measures. Trotters were at higher risk for lesions of the medial malleolus but lower risk for lesions of the distal intermediate ridge of the tibia than were pacers. Horses with bilateral OC lesions and lateral trochlear ridge (LTR) lesions started fewer races at 2 years of age than those with unilateral lesions or without LTR lesions.

CONCLUSIONS

Osteochondrosis seemed to have minimal effect on racing performance in this cohort, although horses with bilateral and LTR lesions started fewer races at 2 years. There was evidence for different distribution of OC lesions among pacers and trotters, which should be explored further. Standardbreds undergoing early removal of tarsal OC lesions can be expected to perform equivalently to their unaffected counterparts.

Problems and pointers in osteochondrosis: Twenty years on

Twenty years ago a supplement of Equine Veterinary Journal was devoted to equine osteochondrosis (OC) and recognised the importance of this developmental disease to the equine industry. In the accompanying editorial several controversial issues were identified and a number of areas for further research were highlighted. Today, equine OC is still a major clinical problem, but the on-going research has resulted in much improved knowledge and understanding of this highly complicated disease. There is still conflicting evidence on the prevalence of OC due to the dynamic character of the condition, widely varying definitions in the literature, and the range of joints affected. Nevertheless there is now convincing evidence that early vascular damage, leading to chondronecrosis, is the major mechanism of onset. The aetiological factors that determine whether a horse will develop clinical signs of OC remain obscure and the complex nature of OC and its multi-factorial character has been clearly demonstrated by genetic studies. These have shown a multitude of loci on a variety of chromosomes linked to osteochondrotic phenotypes, depending on the type of manifestation of OC, the joint involved and the breed. The controversy surrounding the possible key role of copper in the pathogenesis of OC in the early 1990s has evolved into a more limited contribution to repair thus making it just one of the many environmental factors that may have an effect on the occurrence of OC, but not a decisive one. The semantic debate concerning the most appropriate nomenclature seems to have crystallised into a consensus on terminology at three levels: OC or osteochondritis dissecans (OCD) for the disturbance in the process of endochondral ossification, juvenile ostechondral conditions (JOCC) for all joint and growth plate related disorders, and developmental orthopaedic diseases (DOD) for the full range of skeletal conditions in young horses. Future progress in improved management of OC can be expected from more research on cellular and molecular processes and the influences that determine the process of endochondral ossification, the process of articular cartilage maturation, and from epidemiological studies quantifying the long-term effects of OC on health and performance.