Flexion test

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A flexion test is a preliminary veterinary procedure performed on a horse, generally during a prepurchase or a lameness exam. The purpose is to accentuate any pain that may be associated with a joint or soft-tissue structure, allowing the practitioner to localize a lameness to a specific area, or to alert a practitioner to the presence of sub-clinical disease that may be present during a pre-purchase exam.

Contents

Performing a flexion test

The animal's leg is held in a flexed position for 30 seconds to up to 3 minutes (although most veterinarians do not go longer than a minute), [1] and then the horse is immediately trotted off and its gait is analyzed for abnormalities and unevenness. [2] Flexions stretch the joint capsule, increase intra-articular and subchondral bone pressure, and compress surrounding soft tissue structures, [1] which accentuates any pain associated with these structures.

An increase in lameness following a flexion test suggests that those joints or surrounding soft tissue structures may be a source of pain for the horse. The horse may take a few uneven steps, or may be lame for several minutes following the procedure. Flexion tests are considered positive if lameness is increased, although usually lameness is forgiven for the first few steps following flexion. The horse's response should be graded with each flexion and recorded. This allows comparison in lameness when rechecking after treatment has been implemented. [1]

In addition to watching for lameness in the flexed limb, the examiner also looks for lameness in the standing, contralateral (opposite) limb. An increase in lameness associated with the contralateral limb can suggest certain causes pain, such as bilateral hock or carpal disease. [1]

Distal limb flexion

The distal (lower) limb flexion applies the most pressure to the fetlock, pastern, and coffin joints. This flexion is usually performed by pulling the toe of the hoof backward towards the cannon bone, and holding sustained pressure on the joints. The fetlock and phalanges may be somewhat isolated by changing technique, but these joints are never completely isolated from the others, especially in the hind limbs. False positive results from this flexion are especially common in the front fetlock joints. [1]

Carpal flexion

The carpal (knee) flexion test is performed by pulling the cannon bone up towards the radius. In a normal horse, the heels of the foot should contact the animal's elbow. Positive results are usually strongly supportive of carpal disease, but negative results do not rule it out. [1]

Elbow flexion

Elbow flexion is usually only performed when joint abnormality is found during physical examination. Flexion may be performed by lifting the forelimb (antebrachium) so that it is parallel to the ground, while allowing the knee and distal limb to hang free to help prevent pressure on these joints. Unfortunately, elbow flexion often produces some flexion in the shoulder, and these joints are difficult to localize. [1]

Upper forelimb flexion

There are two main methods of upper forelimb flexion. The first method involves pulling the limb forward, so that the elbow flexes and the shoulder extends. This method tends to place more strain on the structures of the caudal elbow and cranial shoulder, and is best at localizing lameness to the bicipital bursa or the supraglenoid tubercle of the scapula, but also places strain on the biceps and triceps muscles and tendons, and the olecranon. The alternative method involves pulling the limb caudally, which flexes the shoulder and extends the elbow. [1]

Hock flexion

Hock flexion is almost always accompanied by flexion of the fetlock, stifle, and hip joints, so a positive flexion does not clearly indicate hock pain. [1] A very marked response is actually more common with stifle pain, rather than hock pain. [3] The flexion is performed by pulling the cannon bone upward so that the upper joints of the leg flex, while avoiding flexion of the fetlock joint or significant pressure on the flexor tendons. [1]

A flexion test that produces lameness on the contralateral, standing limb usually occurs with sacroiliac disease. [1]

The navicular wedge test is used to localize any cause of lameness in the heel of the hoof. A wedge is placed directly under the frog, which applies pressure to the frog. A second method, involving placing the hoof on a wedge so the toe is lifted up relative to the heel, subsequently increases deep digital flexor tendon tension and pressure on the navicular bone. In both cases, the opposite limb is held off the ground to force weight onto the affected limb. The horse is held in this position for 1 minute, then trotted off as in other flexion tests. [1]

Problems with flexion tests

Flexion tests are rather nonspecific, as each test flexes multiple joints. So while they can help localize a lameness issue to one particular leg, or even to a few joints in the leg, they can not pinpoint it. Additionally, flexion tests affect not only the joints that are being flexed, but also the surrounding soft tissue structures around the joint. [1]

Flexion tests may also produce false positives and false negatives. Both the force applied and the time a flexion test is performed can affect outcome. [4] For this reason, it is best if the same person performs flexions of a joint on both legs, and for the same amount of time, to help standardize the response. The degree of lameness can increase significantly with repeated flexions. Certain areas, such as tissues of the fetlock joint, are more sensitive to flexion tests over other tissues, such as those in the pastern and hoof. [5] The flexion test is less useful to evaluate for subclinical joint disease, since a significant number of sound, unaffected horses can produce slightly positive results. [6]

Additionally, forelimb flexion tests have been shown to have poor predictive value for future soundness or unsoundness, and are best interpreted in cases of clinical lameness, joint effusion, reduced range of motion, or pain on palpation. [2] Unfortunately, a positive response to forelimb flexion tests is one reason horses may be deemed unsuitable for purchase during the prepurchase exam. The wide range of significance attributed to these tests varies according to opinion and the experience of the examiner. While there have been many purchase exams discontinued solely because a positive response to a flexion test in one or both forelimbs, there's really nothing in the veterinary literature to support such an action. Due to the variable response to the test depending on such things as the force applied, duration of the test, age of the horse and the day of examination, discontinuation of a prepurchase examination based solely on a failed forelimb flexion test is probably unwarranted. [7]

Related Research Articles

Navicular bone Small bone found in the feet of most mammals

The navicular bone is a small bone found in the feet of most mammals.

Upper limb

The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulder, elbow, wrist and knuckle joints. In humans, each upper limb is divided into the arm, forearm and hand, and is primarily used for climbing, lifting and manipulating objects.

Hock (anatomy)

The hock, or gambrel, is the joint between the tarsal bones and tibia of a digitigrade or unguligrade quadrupedal mammal, such as a horse, cat, or dog. This joint may include articulations between tarsal bones and the fibula in some species, while in others the fibula has been greatly reduced and is only found as a vestigial remnant fused to the distal portion of the tibia. It is the anatomical homologue of the ankle of the human foot. While homologous joints occur in other tetrapods, the term is generally restricted to mammals, particularly long-legged domesticated species.

Laminitis Disease of the feet of hooved animals

Laminitis is a disease that affects the feet of ungulates and is found mostly in horses and cattle. Clinical signs include foot tenderness progressing to inability to walk, increased digital pulses, and increased temperature in the hooves. Severe cases with outwardly visible clinical signs are known by the colloquial term founder, and progression of the disease will lead to perforation of the coffin bone through the sole of the hoof or being unable to stand up, requiring euthanasia.

Navicular syndrome, often called navicular disease, is a syndrome of lameness problems in horses. It most commonly describes an inflammation or degeneration of the navicular bone and its surrounding tissues, usually on the front feet. It can lead to significant and even disabling lameness.

Bone spavin is a bony growth within the lower hock joint of horse or cattle. It is caused by osteoarthritis, and the degree of lameness that results can be serious enough to end a horse's competitive career.

Bowed tendon

Tendinitis/tendonitis is inflammation of a tendon. Many times, the tendon tissue is torn. A bowed tendon is a horseman's term for a tendon after a horse has sustained an injury that caused the tendon fibers to be torn, and then healed with "bowed" appearance.

Equine conformation Evaluation of a horses bone and muscle structure

Equine conformation evaluates a horse's bone structure, musculature, and its body proportions in relation to each other. Undesirable conformation can limit the ability to perform a specific task. Although there are several faults with universal disadvantages, a horse's conformation is usually judged by what its intended use may be. Thus "form to function" is one of the first set of traits considered in judging conformation. A horse with poor form for a Grand Prix show jumper could have excellent conformation for a World Champion cutting horse, or to be a champion draft horse. Every horse has good and bad points of its conformation and many horses excel even with conformation faults.

Fetlock

Fetlock is the common name in horses, large animals, and sometimes dogs for the metacarpophalangeal and metatarsophalangeal joints.

Equine anatomy Descriptive scheme

Equine anatomy refers to the gross and microscopic anatomy of horses, ponies and other equids, including donkeys, mules and zebras. While all anatomical features of equids are described in the same terms as for other animals by the International Committee on Veterinary Gross Anatomical Nomenclature in the book Nomina Anatomica Veterinaria, there are many horse-specific colloquial terms used by equestrians.

Osselet is arthritis in the fetlock joint of a horse, caused by trauma. Osselets usually occur in the front legs of the horse, because there is more strain and concussion on the fetlock there than in the hind legs. The arthritis will occur at the joint between the cannon bone and large pastern bone, at the front of the fetlock.

Skeletal system of the horse

The skeletal system of the horse has three major functions in the body. It protects vital organs, provides framework, and supports soft parts of the body. Horses typically have 205 bones. The pelvic limb typically contains 19 bones, while the thoracic limb contains 20 bones.

Lameness is an abnormal gait or stance of an animal that is the result of dysfunction of the locomotor system. In the horse, it is most commonly caused by pain, but can be due to neurologic or mechanical dysfunction. Lameness is a common veterinary problem in racehorses, sport horses, and pleasure horses. It is one of the most costly health problems for the equine industry, both monetarily for the cost of diagnosis and treatment, and for the cost of time off resulting in loss-of-use.

In horse trading, an equine prepurchase exam is an examination of a horse requested by the buying party prior to the purchase, in order to identify any preexisting problems which may affect a horse's future performance and reduce buyer risk. The inspection usually consists of four phases in which a veterinarian examines all aspects of the horse's health.

Jumping (horse)

Jumping plays a major role in many equestrian sports, such as show jumping, fox hunting, steeplechasing, and eventing. The biomechanics of jumping, the influence of the rider, and the heritability of jumping prowess have all been the focus of research.

Limbs of the horse Structures made of bones, joints, muscles, tendons, and ligaments

The limbs of the horse are structures made of dozens of bones, joints, muscles, tendons, and ligaments that support the weight of the equine body. They include two apparatuses: the suspensory apparatus, which carries much of the weight, prevents overextension of the joint and absorbs shock, and the stay apparatus, which locks major joints in the limbs, allowing horses to remain standing while relaxed or asleep. The limbs play a major part in the movement of the horse, with the legs performing the functions of absorbing impact, bearing weight, and providing thrust. In general, the majority of the weight is borne by the front legs, while the rear legs provide propulsion. The hooves are also important structures, providing support, traction and shock absorption, and containing structures that provide blood flow through the lower leg. As the horse developed as a cursorial animal, with a primary defense mechanism of running over hard ground, its legs evolved to the long, sturdy, light-weight, one-toed form seen today.

The treatment of equine lameness is a complex subject. Lameness in horses has a variety of causes, and treatment must be tailored to the type and degree of injury, as well as the financial capabilities of the owner. Treatment may be applied locally, systemically, or intralesionally, and the strategy for treatment may change as healing progresses. The end goal is to reduce the pain and inflammation associated with injury, to encourage the injured tissue to heal with normal structure and function, and to ultimately return the horse to the highest level of performance possible following recovery.

Stay apparatus

The stay apparatus is a group of ligaments, tendons and muscles which "lock" major joints in the limbs of the horse. It is best known as the mechanism by which horses can enter a light sleep while still standing up. It does, however, exist in other large land mammals, where it plays a role in reducing fatigue while standing. The stay apparatus allows animals to relax their muscles and doze without collapsing.

Angular limb deformity Medical condition

Angular limb deformity is a pathological deformity in the spatial alignment of any limb in quadrupedal animals. The term encompasses any condition in such an animal wherein a limb is not straight. It most commonly occurs in the carpal joint of the forelimbs, manifesting as the limb pointing outward or inward, deviating from normal development.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 Baxter, Gary (2011). Manual of Equine Lameness. Wiley-Blackwell. ISBN   978-0-8138-1546-6.
  2. 1 2 Ramey, DW. Prospective Evaluation of Forelimb Flexion Tests in Practice: Clinical Response, Radiographic Correlations, and Predictive Value for Future Lameness. Proc. AAEP, 1997, Vol. 43; 116-119.
  3. ↑ Dyson SJ. Lameness Associated with the Stifle and Pelvic Regions. Proc. AAEP, 2002, Vol. 48; 387-411.
  4. ↑ Keg PR, van Weeren PR, Back W, Barneveid A. Influence of the force applied and its period of application on the outcome of the flexion test of the distal forelimb of the horse. The Veterinary Record 1997, 141(18):463-466.
  5. ↑ KEARNEY, C. M., Van WEEREN, P. R., CORNELISSEN, B. P. M., Den BOON, P. and BRAMA, P. A. J. (2010), Which anatomical region determines a positive flexion test of the distal aspect of a forelimb in a nonlame horse?. Equine Veterinary Journal, 42: 547–551.
  6. ↑ Busschers, E. and Van Weeren, P. R. (2001), Use of the Flexion Test of the Distal Forelimb in the Sound Horse: Repeatability and Effect of Age, Gender, Weight, Height and Fetlock Joint Range of Motion. Journal of Veterinary Medicine, Series A, 48: 413–427.
  7. ↑ Ramey 2008, "Flex Test"
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