Ultrasonographic diagnosis of coxofemoral subluxation in horses

Osteoarthritis of the coxofemoral joint in 24 horses: Evaluation of radiography, ultrasonography, intra-articular anaesthesia, treatment and outcome

BACKGROUND

Few case reports describe equine coxofemoral joint osteoarthritis (CFJOA).

OBJECTIVES

To evaluate diagnostic findings and outcome of horses with CFJOA and to provide a score facilitating radiographic assessment.

STUDY DESIGN

Retrospective case series.

METHODS

History, clinical signs, ultrasonographic, radiographic and intra-articular anaesthesia findings, treatments, outcome, and necropsy results of horses with CFJOA presented between 2002 and 2023 were collated. Radiographic findings were categorised to develop a radiographic score which was applied by two masked examiners. Intra- and inter-observer reliability was determined using weighted Cohen's kappa (Cκ) and the correlation between radiographic and ultrasound findings via Spearman correlation coefficient.

RESULTS

The study included 24 horses (median age 14 years). Most of them (20/24) were chronically lame. Frequent clinical signs included unilateral gluteal muscle atrophy (18/21), lengthening of the stride of the affected limb (13/19) and locomotion on three tracks (13/20). Both imaging modalities enabled evaluation of periarticular osteophytes (correlation coefficient r = 0.64; p = 0.003). Additionally, radiography allowed detection of irregular joint spaces, subchondral bone opacity changes and femoral head flattening/tapering. Inter-observer (Cκ = 0.846) and intra-observer (Cκ = 0.853 and Cκ = 0.842) agreement was excellent. If treated, mostly intra-articular corticosteroids were administered (16/18). Nine horses were euthanised immediately or during follow-up examination. Post-mortem, the Ligamentum capitis ossis femoris was commonly found ruptured. All surviving horses remained lame.

MAIN LIMITATIONS

Retrospective analysis of clinical records and subjective outcome assessment based on owner follow-up with potential recall bias. Due to overall disease severity, associations between different grades of clinical findings, radiographic abnormalities and outcome could not be evaluated.

CONCLUSIONS

Typical clinical signs may indicate CFJOA. Standardised evaluation of ventrodorsal radiographs allows a comprehensive diagnosis. Postmortem findings suggest joint instability as a possible causative factor that may contribute to the poor prognosis and resistance to medical therapy of the disorder.

Computer-assisted surgery for placing toggle constructs across the coxofemoral joints of small equids using a minimally invasive approach-A proof-of-concept cadaveric study

OBJECTIVE

To develop a minimally invasive technique for placing a toggle construct across the coxofemoral joint of small equids using computer-assisted surgery.

STUDY DESIGN

Experimental cadaveric study.

SAMPLE POPULATION

Three pilot specimens: One donkey, one Shetland pony and one Warmblood foal. Six main study specimens: Three Shetland ponies, one American Miniature Horse, one Warmblood foal and one donkey.

METHODS

Experimental surgeries were performed on both coxofemoral joints of each cadaver. Using a minimally invasive surgical approach, 5.5 mm bone canals were drilled through the femur and acetabulum, traversing the coxofemoral joint. Intraoperative guidance was provided by a cone-beam computed tomography (CBCT)-coupled surgical navigation system. A toggle construct was introduced through the bone canals. Surgical accuracy aberrations (SAA) were measured at the femoral entry and exit points and at the acetabular entry point on merged pre- and postoperative CBCT scans. The coxofemoral joint was assessed for articular cartilage damage by gross dissection.

RESULTS

A toggle construct was placed across all 18 coxofemoral joints. The overall median SAA in the main study was 2.8 mm (range: 0.4-8.0 mm). No cartilage damage was found in the cadaveric specimens of the main study.

CONCLUSION

The described technique allowed for the placement of a toggle construct across the coxofemoral joint of small equid cadaveric specimens without prior coxofemoral luxation.

CLINICAL RELEVANCE

This technique may serve as an option for surgical stabilization of coxofemoral joints in small equids. Further biomechanical investigations are required to assess optimal implant positioning and toggle constructs.

Establishment of an ultrasound-guided protocol for the assessment of hip joint osteoarthritis in rabbits-A sonoanatomic study

Ultrasound (US) has emerged as one of the most applied imaging tools to diagnose musculoskeletal disorders and assist in guided intra-articular administrations. Nevertheless, in evaluating the rabbit hip joint, there is a need for an ultrasonographic approach. Therefore, this study aimed to describe the hip sonoanatomy, develop and validate a US-guided protocol to assess the hip joint in rabbits and apply this protocol in vivo. This study was carried out in three phases, phase I: a pilot cadaveric study, to assess the applicability of different US approaches in the hip of rabbits and, consequently, develop a detailed US-guided protocol (2 rabbit cadavers, n = 4 hips); phase II: validation of the established US-guided protocol through a numerical scoring system in healthy joints (11 rabbit cadavers, n = 22 hips), and, lastly, phase III: application of the US-guided protocol in vivo in osteoarthritic joints (5 rabbits, n = 5 hips). A total of six planes were validated, two in the ventral approach and four in the dorsal approach. The ventral transverse plane was deemed more informative regarding the hip joint sonoanatomy, enabling the identification of a greater number of structures when compared to the other planes. Nevertheless, this study suggested that the isolated application of a plane was deemed insufficient for a complete and detailed evaluation of the hip joint anatomy, rendering it necessary to employ other planes complementarily. Furthermore, the established US-guided protocol allowed a definitive diagnosis of OA, and osteophytes and capsular hypertrophy were among the defects most frequently detected. This novel study provided US anatomical landmarks for forthcoming therapeutic research and monitoring of OA development, granting the accurate identification of osseous and cartilaginous defects.

Ultrasound is an accurate method compared to radiography for diagnosing the presence of acute hip luxation in cadaver dogs and can identify the direction of luxation with variable reliability

Acute hip luxation is a common musculoskeletal injury in dogs, with radiographs being the preferred imaging modality for confirming the diagnosis. In large animal and human medicine, ultrasound is often utilized for this purpose. The objectives of this three-part study were to utilize a canine cadaver model to establish ultrasonographic features of hip luxation and evaluate the accuracy and reliability for diagnosing hip luxation with ultrasound. For the first prospective, exploratory study, a cadaver model was developed that allowed manual luxation and subsequent ultrasonography of the hip joint while in four directions of luxation. For the second prospective, anatomic study, a description of the ultrasonographic features for each direction of luxation was created. For the third prospective diagnostic accuracy, observer agreement study, 16 residency-trained and intern veterinarians without prior experience in this technique performed randomized, repeated ultrasound exams on cadaver hips assigned as normal or luxated (equally distributed between the 4 directions). A total of 1140 hip ultrasounds were performed with good accuracy (median, 90.8%; range, 61.4-100%), sensitivity (89.5%), and specificity (80.0%) for diagnosing the presence of hip luxation. Accuracy for identifying the correct quadrant of luxation was significantly lower (mean, 58.6%; range, 24.6-90.8%; P < 0.001). Intraobserver accuracy agreement varied widely from none to almost perfect agreement, and interobserver agreement ranged from slight to moderate agreement. The results of this study supported the use of ultrasound for diagnosing the presence of hip luxation but did not support replacing radiographs for diagnosing the direction of luxation.

Ultrasonographic diagnosis of femoral fractures in large animals

OBJECTIVE

Femoral fractures are often catastrophic in large animals. Radiographic diagnosis is limited by patient size and feasibility, especially in ambulatory settings. Ultrasonography is widely available and may provide an alternative to radiography for definitive diagnosis.

ANIMALS

12 large animals (6 horses, 5 cattle, and 1 elephant).

PROCEDURES

Retrospective analysis of large animal patients diagnosed with femoral fracture by use of femoropelvic ultrasonography (2000 to 2019).

RESULTS

5 of 12 cases were ≤ 1 year of age. The remaining 7 cases were 2 to 33 years of age (median, 13 years). All patients developed severe acute lameness after falling (n = 4), limb entrapment (2), dystocia (1), vehicular collision (1), ipsilateral full limb casting (1), or unknown events (3). All were non-weight-bearing or lame at the walk, including 2 recumbent cattle. Ten cases showed upper limb swelling that was variable in location, and 3 had nonspecific upper limb crepitus. Ultrasonography revealed evidence of diaphyseal (n = 6), greater trochanteric (2), capital physeal (2), and distal femoral (2) fractures. Fracture movement during limb manipulation or weight shifting was sonographically visualized in 5 animals. Radiography confirmed fractures in 3 of 8 animals: 2 bovines with distal femoral fractures detected on standing projections and 1 capital physeal fracture that required ventrodorsal projections under general anesthesia. All animals were euthanized (11) or slaughtered (1 bovine). Postmortem examination confirmed ultrasonographic findings in 10 of 10 necropsied animals.

CLINICAL RELEVANCE

Femoral fractures were not localized nor confirmed in any case prior to ultrasonography. Study findings supported the use of ultrasonography for rapid patient-side diagnosis, prognostication, and decision-making in suspect cases.

Sidewinder gait in horses

Background

Sidewinder gait in horses is poorly understood and characterized by walking with the trunk and pelvic limbs drifting to 1 side.

Hypothesis/objectives

To report causes, clinical and diagnostic features.

Animals

Horses examined at 2 institutions.

Materials and Methods

Retrospective study (2000‐2019). Cases with sidewinder gait, neurological and orthopedic examination, and diagnostic work up or postmortem evaluation were included. Descriptive statistics were performed.

Results

Twenty‐four horses (mean age 18.9 years) of various breeds and both sexes were included. Onset was acute (N = 10), subacute (N = 6), and insidious (N = 8). Electromyography and muscle biopsy supported neurologic disease and further aided in localizing site of lesion (N = 9/9). Neurologic causes included dynamic thoracolumbar spinal cord compression (N = 5), equine protozoal myeloencephalitis (N = 4, confirmed and presumed [2 each]), thoracic myelopathy of unknown etiology (N = 4), gliosis (N = 2), and thrombosis of thoracic spinal cord segments (N = 1). Non‐neurologic causes included osteoarthritis of the coxofemoral joint (N = 4), multiple displaced pelvic fractures (N = 2), bilateral rupture of the ligamentum capitis ossis femoris (N = 1), and severe myonecrosis of multiple pelvic limb muscles (N = 1). Case fatality was 79%.

Conclusion and Clinical Importance

Sidewinder gait is usually observed in older horses and can have neurologic or musculoskeletal etiologies. Electromyography can be used as a diagnostic aid to determine neurologic versus non‐neurologic disease and further localize those of neurologic origin. The condition often has a poor prognosis for function and life.

Successful Treatment of a Coxofemoral Luxation in a Shetland Pony by Closed Reduction and Prolonged Immobilization Using a Full-Body Animal Rescue Sling

A 12-year-old, 170 kg, Shetland pony mare was presented with an acute severe right pelvic limb lameness and concurrent upward fixation of the right patella. The affected limb was rotated externally and adducted with a prominent greater trochanter and the right calcaneal tuber being more proximal than its left counterpart. Radiographic examination revealed complete dislocation of the right femoral head from the acetabular cavity in a dorsal and caudal direction. A closed reduction of the coxofemoral luxation was performed successfully under general anaesthesia. A full-body animal rescue and transportation sling (ARTS) was applied for the recovery. The reduction was followed by a right-sided medial patellar desmotomy. The pony was supported in the ARTS for a total of eight weeks combined with crossties for the first six weeks. Subsequently, the mare was discharged with instructions to slowly increase walking exercise over a period of two months before returning to her intended use. A follow-up after 22 months attested the successful treatment of a coxofemoral luxation by closed reduction and prolonged immobilization resulting in a regularly exercised pony without any residual lameness.

Diagnosis of Soft Tissue Injury in the Sport Horse

For successful diagnosis of soft tissue injuries in the sport horse, localizing the area of injury during clinical and lameness evaluation will be followed in most cases by an ultrasonographic examination. With MRI more available in equine veterinary clinics, this modality can allow for a complete evaluation of soft tissue and osseous structures and is especially useful for evaluation of structures within the hoof capsule. This article discusses special ultrasonographic techniques, an overview of MRI image generation, and the use of contrast computed tomography for diagnosis of soft tissue injuries.

ULTRASOUND-GUIDED INJECTIONS IN HORSES WITH CRANIOVENTRAL DISTENSION OF THE COXOFEMORAL JOINT CAPSULE: FEASIBILITY FOR A CRANIOVENTRAL APPROACH

Intrasynovial access to the equine coxofemoral joint (CFJ) is inherently challenging. Blind injection techniques rely upon inconsistently palpable landmarks, and ultrasound guidance requires expertise for needle placement into the coxofemoral articulation. Aspiration is recommended to confirm intrasynovial placement and avoid sciatic nerve anesthesia. The aim of this observational, descriptive, retrospective study was to evaluate the feasibility for an alternative ultrasound-guided approach in horses with cranioventral distention of the CFJ identified during pelvic ultrasound. Thirteen horses with cranioventral CFJ distention, including 12 with severe pathology, were recruited from 2009 to 2014. Seven were excluded as they were not injected or underwent ultrasound-guided injection using a dorsal approach. The remaining six horses underwent a total of nine injections into the cranioventral recess. With the exception of one foal, all were aged horses (15-29 years) of varying breeds and uses, with prominent lameness due to subluxation (three), luxation (two), and severe osteoarthritis (one). The cranioventral recess was imaged adjacent to the proximal femur using a low-frequency curvilinear transducer placed ventral to the cranial joint margins. Using aseptic technique, spinal needles were placed cranial to the transducer and advanced caudomedially into the distended cranioventral recess. Synovial fluid was retrieved in all cases with one needle placement. Findings indicated that, when distended, ultrasound-guided access to the cranioventral CFJ recess is a feasible alternative approach and may reduce the potential for extra-synovial placement. Distention in this sample of horses was accompanied by severe pathology, also supporting the use of this approach for therapeutic interventions.

The use of computed tomographic three-dimensional reconstructions to develop instructional models for equine pelvic ultrasonography

Ultrasonography has gained increased utility to diagnose pelvic fractures in horses; however, internal pelvic contours can be difficult to appreciate from external palpable landmarks. We developed three-dimensional (3D) simulations of the pelvic ultrasonographic examination to assist with translation of pelvic contours into two-dimensional (2D) images. Contiguous 1mm transverse computed tomography (CT) images were acquired through an equine femur and hemipelvis using a single slice helical scanner. 3D surface models were created using a DICOM reader and imported into a 3D modeling and animation program. The bone models were combined with a purchased 3D horse model and the skin made translucent to visualize pelvic surface contours. 3D models of ultrasound transducers were made from reference photos, and a thin sector shape was created to depict the ultrasound beam. Ultrasonographic examinations were simulated by moving transducers on the skin surface and rectally to produce images of pelvic structures. Camera angles were manipulated to best illustrate the transducer-beam-bone interface. Fractures were created in multiple configurations. Animations were exported as QuickTime movie files for use in presentations coupled with corresponding ultrasound videoclips. 3D models provide a link between ultrasonographic technique and image generation by depicting the interaction of the transducer, ultrasound beam, and structure of interest. The horse model was important to facilitate understanding of the location of pelvic structures relative to the skin surface. While CT acquisition time was brief, manipulation within the 3D software program was time intensive. Results were worthwhile from an instructional standpoint based on user feedback.

Ultrasonographic evaluation of the coxofemoral joint region in young foals

The purpose of this study was to map the coxofemoral region in foals to obtain ultrasonographic reference values for the interpretation of potentially pathological findings in hip joints. Using a 7.5 MHz linear transducer, 38 examinations were carried out: 10 (20 joints) on cadavers and 28 (55 joints) on live healthy foals up to 8 weeks of age. The chosen plane of examination was caudolateral-craniomedial oblique on an imaginary line connecting the greater trochanter and the cranial edge of the tuber sacrale. The relatively thin muscular layer covering the coxofemoral joint allowed good image quality. The evaluated structures included the bone surface of the ilium and acetabulum, the subchondral bone on the femoral head and greater trochanter, the joint cartilage on the femoral head, the fibrocartilaginous acetabular labrum, the femoral capital physis, the cartilaginous layer covering the greater trochanter, the joint capsule and the presence of visible synovial fluid and the gluteal muscles. A bilateral anatomical frozen section in the plane of examination was made in one cadaver. A good correlation was found between ultrasonographic and corresponding anatomical measurements on the frozen section. This study indicated that ultrasound is a valuable diagnostic tool which can provide good image quality in neonates.