ULTRASONOGRAPHIC ANATOMY OF THE NORMAL CANINE CALCANEAL TENDON

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.

Use of Frozen Tendon Allograft in Two Clinical Cases: Common Calcaneal Tendon and Patellar Ligament Rupture

Many surgical techniques have been described in the literature to repair chronic tendon or ligament ruptures. Although direct approximation of the edges is the surgical technique of choice, the use of synthetic, fascia lata, semitendinosus muscle, and small intestinal submucosa grafts has been described to repair large defects or augment tenous repairs. The aim of this paper was to present the long-term outcome of two clinical cases using a common calcaneal tendon cadaver allograft with subsequent application of platelet-rich plasma for chronic ruptures diagnosed by ultrasound, with a chronic defect between both edges. Twenty-four months after common calcaneal tendon rupture and 12 mo after patellar ligament rupture, orthopedic follow-up of both patients showed complete functional recovery and ultrasound findings were consistent with correct integration of the graft in both cases.

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.

Feasibility and repeatability for in vivo measurements of stiffness gradients in the canine gastrocnemius tendon using an acoustoelastic strain gauge

B-mode ultrasound is an established imaging modality for evaluating canine tendon injury. However, full extent of tendon injury often remains difficult to estimate, as small changes in sonographic appearance are associated with large changes in biomechanical strength. The acoustoelastic strain gauge (ASG) is an ultrasound-based tissue evaluation technique that relates the change in echo intensity observed during relaxation or stretching of tendons to the tissue's mechanical properties. This technique deduces stiffness gradient (the rate of change of normalized stiffness as a function of tissue strain) by analyzing the ultrasound dynamic images captured from gradually deforming tissue. ASG has been proven to accurately model strain and stiffness within tendons in vitro. To determine the feasibility and repeatability for in vivo ASG measurements of canine tendon function, stiffness gradients for the gastrocnemius tendons of 10 clinically normal dogs were recorded by two nonindependent observers at three sites (musculotendinous junction, mid tendon, and insertion). Average stiffness gradient indices (0.0132, 0.0141, 0.0136) and dispersion values (0.0053, 0.0054, 0.0057) for each site, respectively, were consistent with published mechanical properties for normal canine tendon. Mean differences of the average stiffness gradient index and dispersion value between observers and between limbs for each site were less than 16%. Using interclass coefficients (ICC), intra-observer (ICC 0.79-0.98) and interobserver (ICC 0.77-0.95) reproducibility was good to excellent. Right and left limb values were symmetric (ICC 0.74-0.92). Findings from this study indicated that ASG is a feasible and repeatable technique for measuring stiffness gradients in canine tendons.

Sonography of the soft tissue structures of the canine tarsus

Currently, there are no available anatomic descriptions of the soft tissue structures that are visible with ultrasound in the canine tarsus. Eight cadaver hindlimbs and 10 clinically normal dogs (15-37 kg) were examined with ultrasound to establish which structures could be visualized in normal dogs. The structures always identified included the long digital extensor tendon, the tibialis cranialis tendon, the joint space, and the three bellies of the extensor digitum brevis muscle on the cranial/dorsal aspect of the tarsus. The lateral digital extensor tendon and the peroneus longus tendon were identified as a single structure on the lateral aspect of the tarsus. The caudal/plantar approach allowed identification of the calcaneal tendon, the deep and superficial digital flexor tendons, the plantar ligament, and the lumbricales and interosseus muscles. The medial collateral ligament can be identified on the medial tarsus of larger dogs. This technique has proved useful in the diagnosis of soft tissue injuries of the canine tarsus, and clinical examples of tibialis cranialis tendinopathy, deep digital flexor tendinopathy, fibrosis surrounding the medial collateral ligament and extent of invasion of a tarsal hemangiosarcoma are described.