A comparison of arthroscopy to ultrasonography for identification of pathology of the equine stifle

Computed tomographic imaging and surgical management of distal insertional avulsion fragments of the caudal cruciate ligament in four horses

OBJECTIVE

To describe cases with caudal cruciate ligament (CdCL) avulsion fragments diagnosed based on computed tomography (CT) examination and report on arthroscopic fragment removal.

ANIMALS

Four Warmblood horses with hindlimb lameness and osseous fragments located in the caudal medial femorotibial joint (mFTJ).

STUDY DESIGN

Short case series.

METHODS

CT and arthroscopic evaluation of the caudal mFTJ were performed. The caudal mFTJ and the insertion of the CdCL on the tibia were assessed and removal of the avulsion fragments was attempted in three horses using a cranial intercondylar approach.

RESULTS

The fragment was not accessible via caudomedial approaches in one horse. A cranial intercondylar approach was used in three horses, allowing removal of the intra-articular fragment in two horses, and removal of two-thirds of the proximal fragment in the last horse. Acute, profuse, arterial bleeding occurred in this horse during surgery with transient postoperative soft tissue swelling. Comorbidities included medial femoral condyle cartilage defects (3), cranial cruciate ligament lesions (2), and medial collateral ligament lesions (2). Horses were followed up for 16 months (median, range 11-28 months), at which point all were back in ridden exercise; owners' satisfaction was good.

CONCLUSION

CT examination confirmed the diagnosis and allowed evaluation of the stifle joint for comorbidities. A cranial intercondylar arthroscopic approach facilitated the removal of CdCL insertional avulsion fragments, although not always complete.

CLINICAL SIGNIFICANCE

A cranial intercondylar approach can allow access to CdCL avulsion fragments, but complications and incomplete removal remain possible.

Diagnostic Performance of Multi-Detector Computed Tomography Arthrography and 3-Tesla Magnetic Resonance Imaging to Diagnose Experimentally Created Articular Cartilage Lesions in Equine Cadaver Stifles

BACKGROUND

The purpose of the study was to determine the diagnostic performance of computed tomographic arthrography (CTA) and 3-Tesla magnetic resonance imaging (MRI) for detecting artificial cartilage lesions in equine femorotibial and femoropatellar joints.

METHODS

A total of 79 cartilage defects were created arthroscopically in 15 cadaver stifles from adult horses in eight different locations. In addition, 68 sites served as negative controls. MRI and CTA (80-160 mL iodinated contrast media at 87.5 mg/mL per joint) studies were obtained and evaluated by a radiologist unaware of the lesion distribution. The stifles were macroscopically evaluated, and lesion surface area, depth, and volume were determined. The sensitivity and specificity of MRI and CTA were calculated and compared between modalities.

RESULTS

The sensitivity values of CTA (53%) and MRI (66%) were not significantly different (p = 0.09). However, the specificity of CTA (66%) was significantly greater compared to MRI (52%) (p = 0.04). The mean lesion surface area was 11 mm² (range: 2-54 mm²). Greater lesion surface area resulted in greater odds of lesion detection with CTA but not with MRI.

CONCLUSIONS

CTA achieved a similar diagnostic performance compared to high-field MRI in detecting small experimental cartilage lesions. Despite this, CTA showed a higher specificity than MRI, thus making CTA more accurate in diagnosing normal cartilage. Small lesion size was a discriminating factor for lesion detection. In a clinical setting, CTA may be preferred over MRI due to higher availability and easier image acquisition.

Ultrasonographic comparison of the intermediate patellar ligament in warmbloods versus quarter horses

Striations are present on ultrasonography of the intermediate (middle) patellar ligament in the transverse plane, which can be confused with tears. Comparison to the contralateral limb is often performed to help differentiate anatomic variation from pathologic change. The purposes of this prospective, observational study were to describe the striation patterns in Warmbloods and Quarter Horses, determine if these patterns are bilaterally symmetrical, and compare striation characteristics between Warmbloods and Quarter Horses. The intermediate patellar ligaments of six Warmblood horses and six Quarter horses, free from clinical signs of hindlimb lameness and in full work, were examined ultrasonographically. Striation pattern, striation number, and the transverse-sectional areas for intermediate patellar ligaments were compared between Warmbloods and Quarter horses. Striation patterns were also compared for the left and right limbs of each horse. A significant difference between breeds was identified at the mid-portion of the intermediate patellar ligament when both left and right ligaments were included (P = 0.02) and when comparing the right intermediate patellar ligament (P = 0.02). There were no other significant breed differences, and a parallel pattern was the most common pattern type. Two-thirds of the horses in this study had bilaterally symmetrical patterns within the distal aspect of their intermediate patellar ligaments, while one-third of the population were asymmetric. These results show that comparison of the contralateral limb during ultrasonography to determine if changes within the distal aspect of the intermediate patellar ligament are normal striations versus tears may lead to misdiagnosis in one-third of horses, regardless of breed. Other signs of pathology on ultrasonography should be used instead.

When radiography and ultrasonography are not enough: the use of computed tomography and magnetic resonance imaging for equine lameness cases

MRI and CT have enhanced our diagnostic abilities for equine lameness beyond what is available using radiography and ultrasonography. This has allowed veterinarians to better prognosticate and treat lameness conditions, improving patient outcomes. This article discusses the basic principles behind MRI and CT, their advantages and disadvantages, the different types of equipment available for clinical use in horses, the typical diagnostic workup prior to pursuing advanced imaging, and common regions where MRI and CT are used clinically. The companion Currents in One Health by Spriet, AJVR, July 2022, discusses even more advanced equine imaging in the form of positron emission tomography. Combined, these future directions of MRI, CT, and positron emission tomography may include improved ability to image standing horses or screen for injury prevention.

Ultrasound screening protocol for osteochondrosis at selected predilection sites in thoroughbred yearlings

Background

Osteochondrosis is a common condition of young horses where there is a failure of endochondral ossification, usually at predisposed sites. The estimated prevalence of osteochondrosis is 33–44%, with radiographic screening of yearlings being used to identify lesions. Radiography has two major limitations: poor sensitivity in detecting cartilaginous lesions and secondly, the exposure of the horse and personnel to ionising radiation. Ultrasonography allows imaging of the articular cartilage and subchondral bone margins and has been shown to be more sensitive in identifying osteochondrosis lesions. However, the ultrasonographic technique for examining joints is operator dependant, resulting in highly variable examinations, thus affecting its reliability and reproducibility as a screening test.

Results

A prospective observational clinical population study was undertaken involving twenty-two clinically normal weanling thoroughbred horses on-farm, describing a detailed protocol of the ultrasonographic examination technique for on-farm screening of common sites of osteochondral disease in the young horse, namely the carpal, metacarpophalangeal, stifle, tarsal and metatarsophalangeal joints.

Conclusion

Two veterinary practitioners used the technique to illustrate the repeatability of the protocol. The step-by-step protocol provides a valuable, reliable, repeatable technique for veterinary professionals performing screening ultrasound in the field.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13620-022-00216-7.

Development of an Ultrasound Technique to Evaluate the Popliteal Complex in the Horse

Simple Summary

The popliteal tendon and muscle are major stabilizers of the human and dog knee. Injury to this complex causes knee pain, and it is generally associated with other injured structures such as the lateral meniscus and/or the cranial cruciate ligament. The equine popliteal complex is poorly reported. Lameness due to stifle pathology is a serious clinical concern in sport horses, and the roll of the popliteal complex in this is unknown. One of the cardinal diagnostic tools on lameness exams is ultrasonography; however, a comprehensive technique to examine the complete popliteal complex (tendon and muscle) in horses has not been reported. The objective of the study was to develop a detailed ultrasound technique of the equine popliteal complex. We present here a detailed ultrasound technique to clearly evaluate the popliteal tendon, its components and variable insertions, the subpopliteal recess, and muscle. This new ultrasound approach is easy to apply by following clear anatomical landmarks, even by inexperienced operators. The technique presented here can be complementary to a routine stifle ultrasound exam.

Abstract

The popliteal tendon and muscle are major stabilizers of the human and dog knee, more specifically the postero-lateral corner. Injury to this complex causes posterior knee pain, and it is generally associated with other injured structures such as the lateral collateral ligament, lateral meniscus, and/or the cranial cruciate ligament. The popliteal complex is poorly reported in the horse, and its specific function has not been determined. Nevertheless, it is likely that it is similar to that of other species, and that injury to it could have similar clinical repercussions. Lameness due to stifle pathology is a serious clinical entity in sport horses. One of the cardinal diagnostic tools in lameness exams is ultrasonography; however, a comprehensive technique to examine the popliteal complex (tendon and muscle) in the horse has not been reported. The objective of the study was to develop a systematic ultrasound technique of the equine popliteal complex that allows identification of the insertion and variations of the popliteal tendon (PopT), as well as examination of the popliteal muscle (PopM). Comparison between anatomical variants among horses was studied in order to identify possible significant differences. For this, 10 university teaching horses were used, hence 20 stifles were examined, several times. With the ultrasound technique presented here, the PopT and PopM are consistently examined. The developed technique allows reliable examination of the popliteal complex in the horse, and it could be included during standard ultrasound examination of equine stifle.

Ex vivo comparison of 3 Tesla magnetic resonance imaging and multidetector computed tomography arthrography to identify artificial soft tissue lesions in equine stifles

OBJECTIVE

To determine the diagnostic performance of computed tomographic arthrography (CTA) and 3 Tesla magnetic resonance imaging (MRI) for detecting artificial meniscal, meniscotibial ligament (MTL) lesions and cruciate ligament (CL) lesions in horses.

STUDY DESIGN

Ex vivo controlled laboratory study.

ANIMALS

Nineteen stifles from adult horses.

METHODS

Stablike defects (n = 84) (16 mm long, 10 mm deep) were created in the menisci (n = 35), CLs (n = 24), and MTLs (n = 25) via arthroscopy prior to MRI and CTA (80 mL contrast at 85 mg/mL per joint). Two radiologists, unaware of the lesions, reached a consensus regarding the presence of lesions, based on 2 reviews of each study. Sensitivity and specificity of MRI and CTA were determined using arthroscopy as a reference and compared with McNemar's tests.

RESULTS

The sensitivity and specificity of MRI (41% and 86% respectively) and CTA (32% and 90% respectively) did not differ (P = .65). The sensitivity (MRI: 24%‐50%; CTA:19%‐40%) and specificity (MRI: 75%‐92%; CTA 75%‐100%) of imaging modalities did not differ when detecting lesions of the menisci, MTLs, and CLs (P = .1‐1.0). The highest sensitivities were achieved when MTLs were evaluated with MRI (50%) and CLs with both modalities (40%).

CONCLUSIONS

The diagnostic performance of CTA was comparable with that of MRI, with a low to moderate sensitivity and high specificity.

CLINICAL SIGNIFICANCE

Computed tomographic arthrography should be considered as an adjunct to diagnose CL injuries. This is important for equine clinicians, as the CL cannot be visualized adequately using basic imaging techniques preoperatively.

Arthroscopic findings and long-term outcomes in 76 sport horses with meniscal injuries (2008-2018)

OBJECTIVE

To report the findings and long-term outcome of 76 sport horses with meniscal injury.

STUDY DESIGN

Retrospective case series.

ANIMALS

Seventy-six horses with 93 meniscal injuries in 85 stifles.

METHODS

Medical records of sport horses diagnosed with meniscal injury during arthroscopy were reviewed. Owner follow up was obtained via telephone interview ≥1.5 years postoperatively. Preoperative and intraoperative findings, and postoperative treatments, were analyzed for potential association with return to athletic performance.

RESULTS

The medial meniscus was involved in 82.8% of cases, with grade 1 injuries diagnosed in 76.3% of menisci. Overall, 85.5% of horses returned to athletic performance, with 40% returning to their previous level. The grade of meniscal injury was associated with long-term outcome (P = .023). The presence of preoperative radiographic abnormalities (P = .259) or additional joint pathology (P = 1.00) was not associated with long-term outcomes. Fifty-nine stifles were treated with an orthobiologic: autologous conditioned serum, platelet-rich plasma, or marrow-derived mesenchymal stem cells. There was no association between the use of any orthobiologic and long-term outcome (P = .394).

CONCLUSION

This is the first report on long-term outcome of sport horses with meniscal injuries following arthroscopic surgery. Overall, the long-term prognosis was fair, with 40% of horses returning to their previous level of use. Severity of the meniscal injury was a prognostic indicator for return to work. The presence of radiographic abnormalities or additional joint pathology, or the use of orthobiologics, was not associated with long-term outcome.

CLINICAL SIGNIFICANCE

These findings can help in prognostication for sport horses with meniscal injuries.

Regenerative Medicine for Equine Musculoskeletal Diseases

Simple Summary

Lameness due to musculoskeletal disease is the most common diagnosis in equine veterinary practice. Many of these orthopaedic disorders are chronic problems, for which no clinically satisfactory treatment exists. Thus, high hopes are pinned on regenerative medicine, which aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. Some regenerative medicine therapies have already made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising but diverse results. This review summarises the current knowledge of commonly used regenerative medicine treatments and critically discusses their use.

Abstract

Musculoskeletal injuries and chronic degenerative diseases commonly affect both athletic and sedentary horses and can entail the end of their athletic careers. The ensuing repair processes frequently do not yield fully functional regeneration of the injured tissues but biomechanically inferior scar or replacement tissue, causing high reinjury rates, degenerative disease progression and chronic morbidity. Regenerative medicine is an emerging, rapidly evolving branch of translational medicine that aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. It includes tissue engineering but also cell-based and cell-free stimulation of endogenous self-repair mechanisms. Some regenerative medicine therapies have made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising results. However, the qualitative and quantitative spatiotemporal requirements for specific bioactive factors to trigger tissue regeneration in the injury response are still unknown, and consequently, therapeutic approaches and treatment results are diverse. To exploit the full potential of this burgeoning field of medicine, further research will be required and is ongoing. This review summarises the current knowledge of commonly used regenerative medicine treatments in equine patients and critically discusses their use.

Characterization of Adult and Neonatal Articular Cartilage From the Equine Stifle

A significant portion of equine lameness is localized to the stifle joint. Effective cartilage repair strategies are largely lacking, however, recent advances in surgical techniques, biomaterials, and cellular therapeutics have broadened the clinical strategies of cartilage repair. To date, no studies have been performed directly comparing neonatal and adult articular cartilage from the stifle across multiple sites. An understanding of the differences in properties between the therapeutic target cartilage (i.e., adult cartilage) as well as potential donor cartilage (i.e., neonatal cartilage) could aid in selection of optimal harvest sites within a donor joint as well as evaluation of the success of the grafted cells or tissues within the host. Given the dearth of characterization studies of the equine stifle joint, and in particular neonatal stifle cartilage, the goal of this study was to measure properties of both potential source tissue and host tissue. Articular cartilage of the distal femur and patella (P) was assessed in regards to two specific factors, age of the animal and specific site within the joint. Two age groups were considered: neonatal (<1 week) and adult (4-14 years). Cartilage samples were harvested from 17 sites across the distal femur and patella. It was hypothesized that properties would vary significantly between neonatal and adult horses as well as within age groups on a site-by-site basis. Adult thickness varied by site. With the exception of water content, there were no significant biochemical differences among sites within regions of the distal femur (condyles and trochlea) and the patella in either the adult or neonate. Neonatal cartilage had a significantly higher water content than adult. Surprisingly, biochemical measurements of cellularity did not differ significantly between neonatal and adult, however, adult cartilage had greater variance in cellularity than neonatal. Overall, there were no significant differences between neonatal and adult glycosaminoglycan content. Collagen per wet weight was found to be significantly higher in adult cartilage than neonatal when averaged across all levels. In terms of biomechanical properties, aggregate modulus varied significantly across the condyles of adult cartilage but not the neonate. Neonatal cartilage was significantly less permeable, and the Young's modulus of neonatal cartilage was significantly higher than the adult. The tensile strength did not vary in a statistically significant manner between age groups. An understanding of morphological, histological, biochemical, and biomechanical properties enhances the understanding of cartilage tissue physiology and structure-function relationships. This study revealed important differences in biomechanical and biochemical properties among the 17 sites and among the six joint regions, as well as age-related differences between neonatal and adult cartilage. These location and age-related variations are informative toward determining the donor tissue harvest site.

Non-weight bearing ultrasonographic examination allows the diagnosis of longitudinal fiber disruption (split) in equine suspensory ligament branches not visible on weight bearing examination

When evaluating suspensory ligament branch splits, there is a discrepancy between high field MRI findings and weight bearing ultrasonographic imaging characteristics. In this descriptive and retrospective case series, ultrasonographic examination was performed on suspensory ligament branches with the limbs in weight bearing and non-weight bearing positions. Suspensory ligament branch splits were defined as linear regions of decreased echogenicity when imaged with the limb in a weight bearing position that increased in size and became anechoic with the limb in a non-weight bearing position. This appearance was considered an indication of pathologic change in the branch. A total of 62 suspensory ligament branches were included in the study from 37 horses, with 14 partial splits, 11 intrasubstance splits, and 14 complete splits of which two had extension of fetlock synovial fluid and synovial membrane through the split. Recheck ultrasonographic examinations performed in eight horses up to 14 months following the initial examination demonstrated persistence of the split in two horses, partial resolution in five horses, and complete resolution in one horse. Ultrasonographic examination using the non-weight bearing approach proved valuable for increasing the lesion conspicuity as compared to the weight bearing images. Certain abnormalities, such as longitudinal fiber disruption (split) in suspensory ligament branches may only be evident when imaged non-weight bearing. The use of this technique provides a more accurate representation of lesion severity and allows for monitoring over time. A longitudinal study is necessary to determine the clinical relevance of suspensory ligament branch splits.

An alternative arthroscopic approach to the caudal pouches of the equine lateral femorotibial joint

BACKGROUND

Current arthroscopic approaches to the caudal pouches of the lateral femorotibial joint are challenging and risk iatrogenic nerve and cartilage injury.

OBJECTIVE

Describe an alternative arthroscopic approach to the caudal pouches of the lateral femorotibial joint in the horse and report intra-articular abnormalities observed during diagnostic stifle arthroscopy of these pouches.

STUDY DESIGN

Descriptive cadaver anatomical and clinical study.

METHODS

An approach to the caudal pouches of the lateral femorotibial joint was developed during clinical surgery using an arthroscopic portal in the popliteal tunnel of the femorotibial joint. Relevant anatomy of the lateral femorotibial joint was reviewed and the arthroscopic landmarks validated on 19 cadaver limbs. The procedure was then incorporated as part of routine inspection of 38 joints in 33 horses.

RESULTS

Entry and examination of both pouches of the caudal lateral femorotibial joint was consistently achieved using an arthroscopic portal immediately cranial to the lateral collateral ligament in both cadaver and clinical limbs, with no adverse effects noted in the latter. Contrary to published descriptions, the division of the pouches was principally formed by a meniscopopliteal septum derived from the joint capsule in all cases, rather than the popliteus muscle and tendon as previously described. Abnormalities were detected in five cases. The finding of bilateral tearing within the popliteus muscle may represent a previously unrecognised arthroscopic condition.

MAIN LIMITATION

Limited case numbers.

CONCLUSION

An arthroscopic portal immediately cranial to the lateral collateral ligament permitted consistent entry into the popliteal tunnel and both pouches of the caudal lateral femorotibial joint.

Pressuring of Acupoints as a Complement to the Diagnosis of Stifle Diseases in Horses

Diseases of the stifle joint remain a challenge for veterinarians. The objective of this study was to achieve a valuable acupuncture suggestive diagnosis to be considered for stifle joint diseases in horses. Thirty-nine nonlame horses involved in different activities were assessed. Acupuncture was independently performed by two evaluators. Reactions of the animal when pressurizing the point suggestive of stifle disease (PSSD), Bladder-20 and/or Bladder-21, were considered as the inclusion criteria for inclusion in the stifle group (SG, n = 31), and the animals with no reactions were assigned to the control group (n = 8). Radiographic and ultrasonographic examinations were performed and evaluated by two independent professionals blinded to the group allocation. Thermographic examination of the PSSD and stifles was also performed, after acclimatization. The ultrasound scores and radiographic findings were higher in the SG than in the control group. Thermography evidenced increased temperature in the PSSD and stifles in the SG. The minimum acupuncture diagnostic criteria for stifle joint disease had a sensitivity of 87.5% and a specificity of 57.0%, and the addition of the acupoints Gallbladder-dorsal tuber coxae, Gallbladder-27, and Spleen-13 to the minimum diagnostic criteria improved sensitivity and specificity. In conclusion, assessing the reaction at the demonstrated acupoints can facilitate a diagnosis of a potential stifle lesion.

Long-term outcome after stifle arthroscopy in 82 Western performance horses (2003-2010)

OBJECTIVE

To report the outcome of horses engaged in Western performance disciplines after stifle arthroscopy and identify prognostic factors for return to performance.

STUDY DESIGN

Retrospective case series.

SAMPLE POPULATION

Eighty-two Western performance horses undergoing stifle arthroscopy.

METHODS

Medical records were reviewed for horses involved in athletic performance/training for various Western performance disciplines and undergoing arthroscopy for lameness localized to the stifle. Follow-up was obtained ≥2 years postoperatively by telephone interviews with the owners. Preoperative and intraoperative findings as well as postoperative treatment were analyzed for their association with return to athletic performance as the primary outcome of interest.

RESULTS

The most common disciplines represented were cutting (n = 38), Western pleasure (n = 13), and reining (n = 13). Approximately 40% (32/82) of horses returned to intended use after surgery. Increased age, higher degree of lameness, longer duration of lameness, and the presence of partial-thickness cartilage lesions decreased the odds of returning to athletic performance. Postoperative therapies (intra-articular: stem cells, corticosteroids, interleukin-1 receptor antagonist protein, hyaluronic acid/polysulfated glycosaminoglycans; systemic: nonsteroid anti-inflammatory drugs, hyaluronic acid/polysulfated glycosaminoglycans, oral joint supplements) did not affect the odds of returning to intended use.

CONCLUSION

Less than half of the Western performance horses that underwent stifle arthroscopy returned to intended use. Older age, longer duration of lameness, and presence of partial-thickness cartilage lesions affected the odds of a horse returning to intended use. Postoperative therapies did not affect the outcome in this population.

CLINICAL SIGNIFICANCE

The prognosis of Western performance horses undergoing stifle arthroscopy is as guarded as that previously reported in horses of other disciplines.

Usefulness of caudomedial-craniolateral oblique radiographic views for the diagnosis of injury to the origin of the cranial cruciate ligament in two horses

CASE DESCRIPTION A 12-year-old mixed-breed mare (horse 1) and 6-year-old Friesian gelding (horse 2) were examined for chronic lameness associated with the stifle joint. CLINICAL FINDINGS Lameness examination revealed effusion of the right (horse 1) or left (horse 2) femoropatellar and medial femorotibial joints and grade 3/5 (horse 1) or 4/5 (horse 2) lameness. A diagnosis of cranial cruciate ligament (CCL) injury with associated mineralization and avulsion (horse 1) or mineralization alone (horse 2) was facilitated in both horses with a caudomedial-craniolateral oblique radiographic view obtained 45° medial to the caudocranial line, which highlighted the origin of the ligament on the caudoaxial aspect of the lateral femoral condyle within the intercondylar fossa. These lesions were subsequently confirmed via CT. TREATMENT AND OUTCOME Arthroscopy of the medial and lateral femorotibial joints was performed for horse 1 and revealed the osseous fragment associated with the CCL, but the fragment could not be removed. Horse 2 was euthanized while anesthetized following CT owing to the poor prognosis. CONCLUSIONS AND CLINICAL RELEVANCE Radiography is typically the first imaging modality attempted for horses with CCL injury, particularly outside the hospital setting. A 45° caudomedial-craniolateral oblique radiographic view may aid in diagnosis of CCL injury when avulsion or mineralization is present. Although this view is not commonly included in the typical radiographic series for imaging of the stifle joint in horses, it should be considered when CCL injury is suspected.

High field magnetic resonance imaging is comparable with gross anatomy for description of the normal appearance of soft tissues in the equine stifle

High field magnetic resonance imaging (MRI) is increasingly used for horses with suspected stifle disease, however there is limited available information on normal imaging anatomy and potential incidental findings. The aim of this prospective, anatomic study was to develop an optimized high field MRI protocol for evaluation of the equine stifle and provide detailed descriptions of the normal MRI appearance of the stifle soft tissues, using ultrasound and gross pathological examination as comparison tests. Nine cadaver limbs were acquired from clinically normal horses. Stifles were evaluated ultrasonographically and then by an extensive 1.5 T MRI protocol. Subsequently, all stifles were evaluated for gross pathologic change. Findings were compared between gross evaluation and MRI imaging and described. No soft tissue structure abnormalities were identified on any evaluation. Specific descriptive findings of the meniscotibial, meniscofemoral, collateral, patellar and cruciate ligaments, and the menisci were reported. The high field MRI protocol described in this study provided high spatial and contrast resolution of the soft tissue structures, and this in turn allowed visualization of detailed structural characteristics, such as striations and variations in signal intensity. Findings supported the use of high field MRI as a modality for the evaluation of the soft tissues of the equine stifle. As clinical availability of this modality increases in the future, authors anticipate that new stifle diseases will be detected that have not previously been identified with other imaging modalities.

Equine meniscal degeneration is associated with medial femorotibial osteoarthritis

BACKGROUND

There is limited information available concerning normal equine meniscal morphology, its degeneration and role in osteoarthritis (OA).

OBJECTIVES

To characterise normal equine meniscal morphology and lesions and to explore the relationship between equine meniscal degeneration and femorotibial OA.

STUDY DESIGN

Ex vivo cadaveric study.

METHODS

Menisci were harvested from 7 normal joints (n = 14 menisci) and 15 joints with OA (n = 30 menisci). A macroscopic femorotibial OA score (cartilage degeneration and osteophytosis) was employed to measure disease severity in each compartment. The femoral and tibial meniscal surfaces were scored for macroscopic fibrillation and tears (1-4). Histological sections (regions: cranial and caudal horn; body) were also scored for microscopic fibrillation and tears (0-3) and inner border degeneration (0-3).

RESULTS

Partial meniscal tears were present on both femoral and tibial surfaces in all 3 regions and most frequently identified on the femoral surface of the cranial horn of the medial meniscus and body of the lateral meniscus. There was a significantly positive correlation between the global medial meniscal macroscopic scores and osteophyte (r = 0.7, P = 0.002) or cartilage degeneration (r = 0.5, P = 0.03) scores within the medial femorotibial joint. The global medial meniscal macroscopic score was greater (P = 0.004) in the advanced OA joints compared with control joints.

MAIN LIMITATIONS

The menisci were principally from abattoir specimens without a known clinical history because of the challenge in obtaining a large number of specimens with a clinical diagnosis of femorotibial OA.

CONCLUSIONS

This study is the first to describe normal equine meniscal morphology and lesions. Meniscal lesions were identified in all segments and on both articular surfaces. Meniscal degeneration significantly correlated with OA severity in the equine medial femorotibial joint. The relationship between OA and meniscal pathology remains to be elucidated.

Fracture of the medial intercondylar eminence of the tibia in horses treated by arthroscopic fragment removal (21 horses)

BACKGROUND

Fractures of the medial intercondylar eminence of the tibia (MICET) are scarcely reported in horses.

OBJECTIVES

To report the clinical and diagnostic findings, surgical treatment and outcome in a series of horses presented with MICET fracture and treated with arthroscopic fragment removal.

STUDY DESIGN

Multicentre retrospective case series.

METHODS

Case records of horses diagnosed with MICET fractures that had undergone surgical treatment were reviewed. Follow-up information was obtained from re-examination visits and/or owners.

RESULTS

Twenty-one cases were identified at 9 equine hospitals between 2004 and 2016. A history of trauma and acute onset of lameness was reported in 12 horses. All cases underwent fracture removal via arthroscopy of the medial femorotibial joint. The cranial cruciate ligament was intact in 6 horses and damaged in 15 horses (damage was ≤25% [n = 9], 25-50% [n = 4] or ≥50% [n = 2] of the cross-sectional area). The cranial ligament of the medial meniscus was damaged in 11 horses (≤25% [n = 8], 25-50% [n = 3]). The medial meniscus was damaged in 5 horses and articular cartilage damage was identified in 14 horses (mild [n = 8], moderate [n = 6]). Follow-up information (median 14 months; 4 months-6 years) was available for 20 cases; 2 horses were sound but convalescing; 13 horses were sound and returned to their previous or expected use. Of the 4 horses with the most severe changes to the articular soft tissue structures, 2 remained lame and 2 were subjected to euthanasia because of persistent lameness.

MAIN LIMITATIONS

The retrospective, multicentre nature of this study and the limited number of horses are the main limitations.

CONCLUSIONS

Fractures of the MICET are commonly associated with a traumatic event. Prompt diagnosis and early arthroscopic removal of the fracture are recommended.