Magnetic Resonance Imaging, Computed Tomography, and Gross Anatomy of the Canine Tarsus

Orthopedic Imaging: A Practical Clinical Guide

Many imaging options are available to the practitioner both in-house and on a referral basis to help make a definitive diagnosis for orthopedic injuries. To guide treatment, a complete understanding of the nature and extent of the injury is ideal. While a thorough orthopedic physical examination is the first step, a complete diagnostic work-up will include at least one and often more than one imaging modality. The goal of this article is to discuss the imaging options for some of the more common orthopedic issues encountered in dogs to help guide the practitioner through the selection of which should be considered to accomplish a diagnosis.

Usefulness of Imaging Techniques in the Diagnosis of Selected Injuries and Lesions of the Canine Tarsus. A Review

Simple Summary

Tarsal joint lesions are uncommon in dogs but may lead to serious health problems. The most common diseases involving the tarsal joint are osteochondrosis, fractures and injuries of the Achilles tendon. The basis for the diagnosis of lesions in the tarsus is a thorough orthopedic examination, sometimes performed under sedation. Imaging modalities such as radiography, ultrasonography, magnetic resonance imaging or computed tomography can facilitate the detection and assessment of lesions in the canine tarsal joint. The aim of this paper is to characterize and compare the usefulness of imaging techniques available in veterinary medicine for the diagnosis and evaluation of lesions and injuries affecting the tarsal joint in dogs.

Abstract

Tarsus lesions are not common in dogs, but they can cause serious health problem. They can lead to permanent changes in the joint and, in dogs involved in canine sports, to exclusion from training. The most common diseases and injuries involving the tarsal joint are osteochondrosis, fractures and ruptures of the Achilles tendon. These conditions can be diagnosed primarily through accurate orthopedic examination, but even this may be insufficient for performing a proper diagnosis. Imaging modalities such as radiography, ultrasonography, magnetic resonance imaging or computed tomography can facilitate the detection and assessment of lesions in the canine tarsal joint. This review paper briefly presents some characteristics of the above-mentioned imaging techniques, offering a comparison of their utility in the diagnosis of lesions and injuries involving the canine tarsus.

Magnetic resonance imaging of the normal dromedary camel tarsus

Background

Magnetic resonance imaging (MRI) is the most versatile and informative imaging modality for the diagnosis of locomotor injuries in many animal species; however, veterinary literature describing the MRI of the dromedary camel tarsus is lacking. Our purpose was to describe and compare the MRI images of twelve cadaveric tarsi, examined in a 1.5 Tesla MRI scanner, with their corresponding anatomical gross sections. Turbo spin-echo (TSE) T1-weighted (T1), T2-weighted (T2), proton density-weighted (PD), and short tau inversion recovery (STIR) sequences were obtained in 3 planes. Tarsi were sectioned in sagittal, dorsal, and transverse planes. MRI images from different sequences and planes were described and compared with the anatomical sections.

Results

The soft and osseous tissues of the dromedary camel tarsus could be clearly defined on MRI images and corresponded extensively with the gross anatomic sections. The obtained MRI images enabled comprehensive assessment of the anatomic relationships among the osseous and soft tissues of the camel tarsus. Several structure were evaluated that cannot be imaged using radiography or ultrasonography, including the transverse inter-tarsal ligaments, the talocalcaneal ligament, the short dorsal ligament, branches of the short medial and lateral collateral ligaments and the tarsometatarsal ligaments. Specific anatomical features regarding the dromedary camel tarsus were identified, including the fused second and third tarsal bone, an additional bundle of the short medial collateral ligament connecting the talus and metatarsus and the medial and lateral limbs of the long plantar ligament.

Conclusions

MRI images provided a thorough evaluation of the normal dromedary camel tarsus. Information provided in the current study is expected to serve as a basis for interpretation in clinical situations.

Description and outcome of prosthetic ligament placement for stabilization of medial or dorsomedial tarsometatarsal joint luxation in dogs and cats: 16 cases (2004-2017)

OBJECTIVE

To describe prosthetic ligament placement for reduction and stabilization of medial or dorsomedial tarsometatarsal joint luxation in dogs and cats and to report complications and postoperative outcomes for patients that underwent that procedure.

ANIMALS

14 dogs and 2 cats with medial or dorsomedial tarsometatarsal joint luxation.

PROCEDURES

The electronic database of a referral surgery practice was searched to identify records of dogs and cats with tarsometatarsal joint luxation that underwent prosthetic ligament placement between January 2004 and March 2017. For each study subject, information extracted from the medical record included signalment, a description of the tarsometatarsal joint injury, durations of anesthesia and surgery, and intraoperative and postoperative care and complications. Radiographic images were also reviewed. The long-term outcome for study subjects was assessed by administration of a standardized questionnaire to owners.

RESULTS

Prosthetic ligament placement successfully stabilized the luxated tarsometatarsal joint in all 16 patients. Six patients developed minor postoperative complications, which included bandage-associated dermatitis or ulceration (n = 5) and orthopedic wire failure (1). No major or catastrophic complications were reported. All 13 owners who completed the questionnaire perceived that the described technique resulted in satisfactory long-term function for their pets.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that prosthetic ligament placement was a technically simple procedure that achieved satisfactory long-term stabilization of the tarsometatarsal joint in small animal patients with medial or dorsomedial luxation of the joint. Prosthetic ligament placement may be an alternative to arthrodesis for tarsometatarsal joint stabilization in appropriate patients.

Differentiation of Anatomic Entities in the Dog Stifle Joint Following S10B Plastination: Comparative Colorimetric and Radiological Investigations

The knee joint is not only the most important and complex structure to present during anatomy lectures, but also a significant region for radiologists and orthopedicians. The objectives of this paper are: 1) to evaluate the efficacy of plastinated specimens by measuring colorimetric differentiation and 2) to compare the anatomical structures of the images obtained from computed tomography (CT) and silicone plastination cross-sections and perform three-dimensional (3D) reconstructed models of the specimens. A total of 16 knee joints selected from the 10% formalin fixed/dissected group (n=6), non-fixed/dissected group (n=6) and non-dissected whole knee joint group (n=4) were scanned by CT and plastinated by using the S10B silicone technique. The color changes of the structures were quantitatively determined with the colorimeter device. Plastinated whole knee joints were cut transversally with a band saw and compared with CT images. Finally, 3D reconstruction of the knee joints was performed from CT images with the 3D reconstruction program. There were statistically significant differences between the fixed and non-fixed groups in terms of color changes (p<0.001). The anatomical structures were identified and matched in the cross-sections of plastinates and corresponding CT images. It was observed that plastinated samples were elastic, durable and non-hazardous specimens to use in the veterinary orthopedics and anatomy courses and lectures. It has been found that fixation was useful for the final product morphology. It is thought that the 3D images obtained from this study will support comprehension of the relationships between the bones, muscles, and ligaments.

Computed tomography and magnetic resonance imaging study of a normal tarsal joint in a Bengal tiger (Panthera tigris)

Background

In this research, using computed tomography (CT) and magnetic resonance imaging (MRI), we provide a thorough description of the standard appearance of a right tarsal joint in a Bengal tiger (Panthera tigris). CT scans were performed using a bone and soft tissue window setting, and three-dimensional surface reconstructed CT images were obtained. The MRI protocol was based on the use of Spin-echo (SE) T1-weighted and Gradient-echo (GE) STIR T2-weighted pulse sequences. Magnetic resonance (MR) images were taken in the transverse, sagittal and dorsal planes. We also performed anatomical dissections to facilitate the interpretation of the different structures of the tarsus joint and allow comparisons with CT and MRI images.

Results

The CT images allowed us to observe differences between the bones and soft tissues of the tarsal joint. When applying the bone window setting, the obtained footage showed the anatomy between the medulla and cortex. Additionally, the trabecular bone was delineated. By contrast, the soft tissue window allowed the main soft tissue structures of the tarsal joint, including ligaments, muscles and tendons, to be differentiated. Footage of the main anatomical structures of the standard tiger tarsus was obtained through MRI. The SE T1-weighted images showed the best evaluation of the cortical, subchondral and trabecular bone of the tibia, fibula, tarsus and metatarsus bones. Nonetheless, the GE STIR T2-weighted images allowed us to better visualize the articular cartilage and synovial fluid. In both MRI pulse sequences, the ligaments and tendons appeared with low signal intensity compared with muscles that were visible with intermediate signal intensity.

Conclusions

The results of this CT and MRI study of the Bengal tiger tarsal joint provide some valuable anatomical information and may be useful for diagnosing disorders in this large non-domestic cat.

Short and long-term outcome following surgical stabilization of tarsocrural instability in dogs

Objectives: To evaluate the outcome and complications following surgical stabilization of canine tarsocrural luxations.

Methods: Medical records of dogs which were surgically treated for tarsocrural joint instability between February 2007 and June 2014 were reviewed. Surgical technique, complications and long-term outcome (via questionnaire and Canine Brief Pain Inventory) were assessed.

Results: Twenty-four dogs (26 joints) were included. All injuries were traumatic. All joints had associated fractures; malleolar in 21/26 limbs (13/26 medial). Eight joints had internal fracture fixation and transarticular external skeletal fixator, six had external fixator alone, four had prosthetic ligaments with external fixator, and four had prosthetic ligaments with external coaptation. Two joints had pantarsal arthrodesis and two primary ligament repair. Complications occurred in 24/26 limbs giving 45 distinct complications; 16 were minor, 29 major, and 31 complications were external fixator associated. Prosthetic ligaments were significantly associated with major complications (p = 0.017); five out of eight required subsequent removal between 105–1006 days. Cost was significantly associated with major complications (p = 0.017) and soft tissue wounds (p = 0.03). Long-term lameness was seen in nine of 14 dogs. There was no association between pain severity (p = 0.3) and pain interference scores (p = 0.198) when comparing stabilization methods.

Clinical significance: Complications are common; however many are external fixator related. Prosthetic ligaments are significantly associated with major complications. Regardless of technique, a degree of ongoing lameness is likely.

Musculoskeletal MRI

MRI has the unique ability to detect abnormal fluid content, and is therefore unparalleled in its role of detection, diagnosis, prognosis, treatment planning and follow-up evaluation of musculoskeletal disease. MRI in companion animals should be considered in the following circumstances: a definitive diagnosis cannot be made on radiographs; a patient is nonresponsive to medical or surgical therapy; prognostic information is desired; assessing surgical margins and traumatic and/or infectious joint and bone disease; ruling out subtle developmental or early aggressive bone lesions. The MRI features of common disorders affecting the shoulder, elbow, stifle, carpal, and tarsal joints are included in this chapter.