Arthroscopic findings in horses with subtle radiographic evidence of osteochondral lesions of the medial femoral condyle: 15 cases (1995–2002)

Ultrasonographic assessment of equine metacarpal cartilage thickness is more accurate than computed tomographic arthrography

Articular cartilage can be directly imaged using ultrasonography. The fetlock is a common site of osteochondrosis, with the sagittal ridge of the third metacarpal bone most commonly affected. In osteochondrosis, cartilage thickening may be an initial finding. This postmortem study investigated the ability of ultrasonography to accurately measure the dorsodistal articular cartilage of the third metacarpal bone in young horses, compared to computed tomographic arthrography (CTA) and histological measurements. A total of 33 metacarpophalangeal joints from 18 horses between the ages of 12 days and 10 months old were imaged ultrasonographically and with CTA and sectioned and measured using histology. Imaging measurements were made by two observers. Despite overall weak agreement between ultrasonography and histology, the best agreement was at the distal aspect of the sagittal ridge of the third metacarpal bone. Interobserver agreement at this site was also moderate. CTA showed poor agreement overall with histology. Cartilage thickness decreased with age on ultrasonography, CTA, and histology. In conclusion, ultrasonography is a more accurate imaging modality than CTA in the assessment of cartilage in young horses.

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.

Chondromalacia of the cranial medial femoral condyle; its occurrence and association with clinical outcome in a population of adult horses with stifle lameness

BACKGROUND

Chondromalacia of the cranial medial femoral condyle (CMFC) is a potential cause of stifle lameness in adult horses. However, there is scant published evidence of either its occurrence or its clinical significance.

OBJECTIVES

To document the occurrence of CMFC seen during diagnostic arthroscopy in adult horses with stifle lameness and to investigate its prognostic significance.

STUDY DESIGN

Retrospective cohort study.

METHODS

The records were reviewed of all horses with unilateral or bilateral lameness localised to the stifle that underwent diagnostic arthroscopy of the cranial medial femorotibial joint at a UK equine hospital. The surgical findings were noted from each. Case outcomes were determined by unstructured telephone discussions with owners. A satisfactory outcome was defined as a horse that was in ridden work without ongoing anti-inflammatory medication. Multivariable logistic regression was used to create a model with an outcome time point at 12-month post-operatively.

RESULTS

One hundred and four horses were included in the study. CMFC was found in 79. In 25 CMFC was the only finding, 54 horses had CMFC plus other pathology and 25 had other pathology, but no CMFC. At 12 months, horses with CMFC were 9.9 (95% CI 2.2-45.0, P<0.01) times more likely to have an unsatisfactory outcome than horses without CMFC.

MAIN LIMITATIONS

The study relied on retrospective analysis of clinical notes and archived arthroscopy videos. Assessment of outcome was determined by unstructured telephone interview and therefore there is potential for reporting errors to exist.

CONCLUSIONS

CMFC is a common arthroscopic finding in horses with stifle lameness and is significantly associated with an increased likelihood of the horse not being in ridden work at long-term follow-up.

Outcome after arthroscopic treatment of lateral femoral trochlear ridge osteochondrosis in sport horses

Objectives: To determine the short- and long-term outcome for sport horses after arthroscopic treatment of osteochondrosis of the lateral trochlear ridge of the femur.

Methods: A retrospective study was performed using the medical records of horses intended for use as English sport horses. Outcome was obtained through telephone questionnaire.

Results: Thirty-seven horses, mainly Warmbloods, underwent arthroscopic surgery for treatment of lateral femoral trochlear ridge osteochondrosis. Short-term outcome revealed that 27 of 37 horses had no complications. Seven horses had postoperative lameness and effusion which eventually resolved in four horses. Long-term outcome was available for 29 horses, of which 19 were performing to full expectations. Five horses were athletic but at a lower level than expected, and five horses were unable to be used. The depth of the lesion was significantly associated with short-term complications of effusion and lameness. The depth and length of the lesion were not associated with the long-term outcome, but involvement of structures other than the lateral trochlear ridge (patella, medial trochlear ridge) was associated with a worse prognosis.

Clinical significance: The prognosis for sport horses following stifle arthroscopy for lateral trochlear ridge is similar to that reported in other studies and lesions at other sites within the stifle joint.

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

REASONS FOR PERFORMING STUDY

To evaluate and compare the diagnostic capability of arthroscopy and ultrasonography for the detection of pathological change in equine stifle joints. Although descriptions of the arthroscopic and ultrasonographic boundaries of the normal femorotibial joint exist, there are few examples in the literature comparing the pathological changes observed with each imaging modality.

OBJECTIVES

To evaluate and compare arthroscopic and ultrasonographic examinations for characterising pathological change in the stifle joint. To describe how the results of arthroscopic and ultrasonographic examinations may differ in characterising the severity of lesions and to evaluate which lesions are best assessed with each modality.

STUDY DESIGN

Retrospective review of ultrasonographic and arthroscopic examinations.

METHODS

The structures of the stifle joint were evaluated and graded for pathological change by scoring arthroscopic and ultrasonographic examinations. The presence and severity of the lesions were then compared between each modality.

RESULTS

Medial meniscal lesions were detected more often with ultrasonography than with arthroscopy. Conversely, arthroscopy was better for detection of cranial medial meniscotibial ligament (CrMMTL) tearing. Articular cartilage defects were best detected with arthroscopy and periarticular osteophytes of the medial femoral condyle with ultrasonography. Four cases had defects within one of the patellar ligaments, all of which were only characterised with ultrasonography.

CONCLUSIONS

Ultrasonography and arthroscopy should be combined to best evaluate pathology of the stifle, since each modality has its own limitations depending on the location and type of lesion.

Evaluation of a Permanent Synthetic Osteochondral Implant in the Equine Medial Femoral Condyle

OBJECTIVE

To evaluate bone ingrowth, integration, and tolerance of a synthetic osteochondral implant in the medial femoral condyle (MFC) of normal horses.

STUDY DESIGN

Experimental study.

ANIMALS

Adult horses (n = 6).

METHODS

Horses were anesthetized and bilateral femorotibial arthrotomies were performed for placement of 1 implant consisting of polycarbonate urethane with a titanium base in 1 MFC. The contralateral MFC served as a sham-operated control without reaming of cartilage or subchondral bone. Lameness evaluations and radiographs were performed pre-operatively with subsequent monthly lameness exams and radiographs at 6 months. Synovial fluid was collected for analysis from the adjacent femoropatellar joints pre-operatively and at several intervals post-operatively. Horses were euthanatized 6 months post-operatively. Stifles were harvested for gross and histologic evaluations.

RESULTS

Two horses were never lame, 2 were mildly lame, and 1 exhibited moderate lameness. Synovial fluid inflammatory parameters of the adjacent femoropatellar joints were not significantly different. No significant changes occurred radiographically over time in either stifle. Histologic assessment of synovium from the medial femorotibial joint revealed no differences in inflammatory changes between implant and sham stifles. Integration and osteoconductivity of the implant were graded as good in 4 and 3 of 5 specimens, respectively. Complications included joint sepsis resulting in euthanasia (1 horse), persistent lameness (1 horse), incisional seromas (4 horses), and incisional dehiscence (2 horses).

CONCLUSION

Results of this pilot study indicate that the implant was compatible with placement in the MFC of normal horses. Implant design allowed bone ingrowth within the titanium base and provision of a synthetic articular surface.

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.

THREE-DIMENSIONAL ULTRASONOGRAPHIC IN VITRO IMAGING OF LESIONS OF THE MENISCUS AND FEMORAL TROCHLEA IN THE EQUINE STIFLE

The purpose of this in vitro study was to evaluate the value of three-dimensional (3D) ultrasonography for the diagnosis of equine meniscal and trochlear ridge lesions under in vitro conditions. Lesions were created in the isolated meniscus and femoral trochlea of 25 cadaver stifle joints. Cylindric, conic, and cuboid lesions were created on the trochlear ridge. Five different meniscal tear configurations were created. A total of 107 lesions of the trochlear ridge and 103 lesions of the meniscus were created. 3D ultrasonography was performed in a waterbath, using a 7.5 MHz 3D scanner. Trochlear ridge lesions were seen as either hypoechoic or anechoic breaks in continuity or as irregular notches. One-hundred and one out of the 107 trochlear lesions were visible using 2D ultrasonography whereas 104 out of the 107 lesions could be seen using the 3D Cine mode. Three lesions could not be detected by either technique. Eighty-five out of the 103 meniscal lesions were seen with 2D ultrasonography and 90 with 3D Cine mode. Radial tears and horizontal tears were the least commonly visualized 3D. The 3D Cine mode led to a small improvement in lesion detection. 3D ultrasound could be considered as an extension and refinement of the ultrasound techniques already in use and can increase the diagnostic capabilities. However, technical improvements have to be achieved before 3D ultrasound can be used in the daily practice for diagnosis of equine stifle joint disorders.

Characterization of experimentally induced post-traumatic osteoarthritis in the medial femorotibial joint of horses

OBJECTIVE

To study osteoarthritis in the equine medial femorotibial (MFT) joint after a single traumatic injury.

ANIMALS

10 mature horses.

PROCEDURE

In vitro explant cultures were used to determine injury threshold for stifle joint cartilage. Contusive impacts were applied to the medial femoral condyle (MFC), and horses were followed for 84 (n = 5) and 180 days (5). Synovial fluid samples were collected every 14 days for determination of sulphated glycosaminoglycan (sGAG) concentrations. Radiographic and lameness evaluations were performed. Gross and histologic descriptions, and immunohistochemistry, cartilage sGAG content determination, and cartilage aggregate modulus determination were performed at the MFC impact site (MFCi), MFC nonimpact site (MFCn), and medial tibial plateau (MTP).

RESULTS

Synovial fluid sGAG concentration decreased significantly on days 14, 28, 42, and 56 in all horses. Macroscopic and microscopic articular lesions developed within all MFT joints. No radiographic abnormalities were observed. Mild lameness was evident in several horses. No significant differences were found between short-term and longterm cohorts of horses with respect to histologic scores and TUNEL results. On immunohistochemistry, MFCi was positive for COL2-(3/4)C(short). International Cartilage Repair Society scores differed significantly between short-term and long-term cohorts of horses. In all horses, sGAG concentrations were significantly decreased at the MFCi, compared with the MFCn.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of contusive impacts on the MFC of horses results in cartilage lesions that are similar to those described clinically, supporting trauma as a contributing factor in the natural pathogenesis of osteoarthritis.