Ultrasound-guided caudal cervical articular process arthrocentesis is accurate in live horses with and without arthropathy

BACKGROUND

Cervical articular process joint (CAPJ) therapy is advocated for horses with neck disorders. Several ultrasound-guided CAPJ techniques have been described in cadaver studies with 72%-89% intra-articular injection accuracy; however, the CAPJ injection accuracy in clinical equine practice has not been extensively reported.

OBJECTIVES

To describe a modified cranial approach for ultrasound-guided caudal CAPJ injections, to investigate the accuracy of this CAPJ injection technique in live horses, and to assess the effect of CAPJ injection location, laterality, operator, and radiographic CAPJ enlargement on injection accuracy.

STUDY DESIGN

Retrospective case study.

METHODS

Medical records of adult horses in which ultrasound-guided caudal (C4-T1) CAPJ injections were performed using a modified cranial approach between November 2006 and December 2020 were reviewed. Radiographic images of caudal cervical vertebrae were assessed by a blinded radiologist and the degree of CAPJ enlargement was graded using a previously described grading system (Rgrade 1-5b). Ultrasound-guided caudal CAPJ injection accuracy was determined by synovial fluid retrieval during an individual CAPJ injection. Statistical analysis was performed using mixed-effects multivariable logistic model to evaluate the association of CAPJ injection accuracy and the CAPJ injection location, Rgrade, laterality (right, left), and operator.

RESULTS

The study included 149 horses with 177 hospital admissions. Synovial fluid was obtained from 586/658 (89.1%) caudal CAPJs using modified cranial ultrasound-guided approach for CAPJ injections. C6-C7 CAPJ injections had 7-fold higher likelihood (OR = 6.78, 95% CI: 1.67-27.52; p = 0.007) of synovial fluid retrieval compared with C4-C5 CAPJ injections. Operator, CAPJ injection side (left, right), and degree of radiographic CAPJ enlargement did not have significant effects on the success of synovial fluid retrieval from ultrasound-guided caudal CAPJ injections.

MAIN LIMITATIONS

Retrospective study design.

CONCLUSIONS

Intra-articular ultrasound-guided caudal CAPJ injections using a modified cranial approach can be performed accurately in live horses with and without CAPJ arthropathy.

Assessment of intrasynovial injection in horses by contrast-enhanced ultrasonography using air bubbles created by agitation of solution

BACKGROUND

Accuracy of intrasynovial injections can be challenging to assess in a clinical setting in horses. Contrast-enhanced ultrasonography (CEUS) using injectate agitated with air has been used to determine the success rates of synovial injections in human rheumatology.

OBJECTIVES

To assess the diagnostic sensitivity and specificity of CEUS and to describe its clinical use.

STUDY DESIGNS

Cadaveric study followed by a prospective descriptive observational study.

METHODS

Part 1: CEUS was performed following injection of agitated methylene-blue solution targeting 13 different anatomical synovial structures from three equine cadavers. Contrast was seen as hyperechoic dots, patches or lines on ultrasonography. CEUS was classified as positive if contrast was considered to be intrasynovial and negative if contrast was considered to be extrasynovial. A second synoviocentesis was performed to determine if the injection was intrasynovial based on the presence or absence of methylene-blue. Estimates of sensitivity and specificity were calculated. Part 2: CEUS was performed following injection of agitated solutions targeting synovial structures as part of routine investigation and treatment of clinical cases.

RESULTS

Part 1: CEUS was correctly classified as positive or negative in all intrasynovial and extrasynovial injections respectively. The sensitivity estimate was 100% (CI 93%-100%) and the specificity estimates was 100% (CI 16%-100%). Part 2: The technique was used safely for 26 injections (14 horses; 19 different synovial structures) administered to localise or treat lameness. Traumatic intersynovial communications or synovial membrane defects were identified using CEUS in 3 horses.

MAIN LIMITATIONS

The low number of extrasynovial injections in Part 1 resulted in an imprecise specificity estimate.

CONCLUSIONS

In horses, CEUS performed following intended intrasynovial injection can be useful for identifying unsuccessful injections.

Ultrasound-assisted injection of the centrodistal joint in the horse

BACKGROUND

Injection of the centrodistal (CD) joint in the horse is a commonly performed procedure for both diagnostic and therapeutic purposes. This procedure can be technically challenging, and while radiographic guidance has been previously used, ultrasound localised injection of the CD joint has not been described.

OBJECTIVES

The purpose of this study was to explore the feasibility of using ultrasound localisation to increase the accuracy of CD joint injection.

STUDY DESIGN

Experimental method assessment.

METHODS

One operator performed the ultrasound and injection of 24 CD joints in 12 sedated horses. The joints were injected with iohexol (2 ml), sterile saline (1.5 ml) and amikacin (0.5 ml). Dorsoplantar and dorsomedial plantarolateral radiographic projections were obtained immediately after injection to evaluate the presence of contrast material in the CD joint.

RESULTS

The CD joint was successfully injected in 17/24 joints, representing a 70.8% accuracy.

MAIN LIMITATIONS

The horses used in this study were from the University research herd, and not clinical cases. One investigator performed all the ultrasonography and CD joint injections.

CONCLUSIONS

The use of ultrasound localisation could improve success of CD joint injection as well as improve the learning curve of less experienced practitioners learning this procedure.

In vitro evaluation of a medial approach for intra-articular injection of the tarsometatarsal joints of horses

OBJECTIVE

To develop a reliable method for injection of the tarsometatarsal (TMT) joint of horses through a medial approach and to characterize anatomy of the synovial recesses of the TMT joint with CT.

SAMPLE

13 pairs of fresh cadaveric equine tarsi.

PROCEDURES

TMT joints were assessed with radiography and CT. Twelve pairs of TMT joints were assigned to an experienced veterinarian (8 joints) or veterinary student (16 joints) for injection with contrast medium through a medial or a lateral approach. Every TMT joint was then reexamined radiographically and with CT to assess diffusion of contrast medium. The number of attempts for the lateral and medial approaches between and within investigators was evaluated, which included evaluation of the diffusion of contrast solution in relation to the approach used.

RESULTS

All 24 TMT joints were successfully injected, as confirmed with radiography and CT. There was no significant difference in the number of attempts between the medial and lateral approaches and between investigators. No significant difference was detected in the distribution of contrast medium in each synovial recess between the medial and lateral approaches.

CONCLUSIONS AND CLINICAL RELEVANCE

The medial approach described here for injection of the TMT joint of horses was highly reliable. It involved use of an easily palpable anatomic landmark on the mediodistal aspect of the TMT joint. An established alternative method for injection of the TMT joint may be useful in clinical practice for diagnostic and therapeutic purposes, although a medial approach may increase risk of injury to veterinarians.

Comparing the clinical success rate of the dorsolateral approach to the medial approach for injection of the centrodistal joint in the horse

BACKGROUND

Centrodistal joint injection is an important component of lameness evaluation and treatment. Successful injection is poor for the medial approach. The dorsolateral approach is an alternative but has not been validated with contrast medium. Radiograph-guidance has not been studied to determine its necessity or benefit for either approach.

OBJECTIVES

To determine if the dorsolateral approach to the centrodistal joint is more successful than the medial approach. To determine if radiograph-guidance is beneficial.

STUDY DESIGN

Prospective, randomised study.

METHODS

Three operators injected 98 centrodistal joints in total, each horse served as its own control. In Phase 1, injections were performed by standard technique. In the Phase 2, operators were allowed to use radiography to assist needle placement. Contrast deposition was evaluated by a single radiologist.

RESULTS

Without radiographic assistance, 10/25 (40%) joints were successfully injected using either the medial or dorsolateral approach. With radiographic assistance, 19/24 (79%) joints were successfully injected using the medial approach, 11/24 (46%) joints were successfully injected using the dorsolateral approach.

MAIN LIMITATIONS

The population consisted of aged horses representing a variety of breeds with existing osteoarthritis, and multiple operators were recruited.

CONCLUSIONS

The dorsolateral approach was equivalent to the medial approach when traditional injection techniques were used. Radiograph-guidance improved success of the medial approach, but not the dorsolateral approach. Many injections performed from the dorsolateral approach (32/49; 65%) resulted in extensive perivascular subcutaneous contrast deposition after infiltration into the tarsal canal. Further research is needed to improve injection success of the centrodistal joint when using the dorsolateral approach.