lameness Def. Lameness is the result of a change from normal stance and gait caused by either a structural or a functional disorder of one or more of.

lamenesslameness

DefDef.. LamenessLameness is the result of a change from is the result of a change from

normal stance and gait caused by either normal stance and gait caused by either a structural or a functional disorder of a structural or a functional disorder of one or more of the limbs, the neck, or the one or more of the limbs, the neck, or the trunk. trunk.

It is not a disease, but a manifestation of It is not a disease, but a manifestation of either pain or mechanical interference of either pain or mechanical interference of the musculoskeletal system, although a the musculoskeletal system, although a combination of the two frequently exists .combination of the two frequently exists .

Mechanical lamenessMechanical lameness is is best typified by best typified by fibrotic fibrotic myopathymyopathy with its with its characteristic gait characteristic gait abnormality,abnormality,

but can also be the result of but can also be the result of a a restrictionrestriction (eg, tendon (eg, tendon sheath restriction in annular sheath restriction in annular ligament syndrome).ligament syndrome).

Pain-related lamenessPain-related lameness can be can be classified as:classified as:

weightbearing weightbearing (supporting leg)(supporting leg) or or nonweightbearing nonweightbearing (swinging leg)(swinging leg)

lameness, lameness, although lameness most often is although lameness most often is

composed of both. composed of both.

A supporting leg lamenessA supporting leg lameness is is seen when the horse attempts seen when the horse attempts to reduce the amount of time a to reduce the amount of time a particular limb is bearing weight.particular limb is bearing weight.

The horse elevates its head and The horse elevates its head and shifts its weight away from a shifts its weight away from a particular limb during particular limb during weightbearing for a forelimb weightbearing for a forelimb lameness, whereas the opposite lameness, whereas the opposite is true for a hindlimb lameness. is true for a hindlimb lameness.

Factors that predispose to Factors that predispose to lamenesslameness

physical immaturityphysical immaturity :: eg, bones that are anatomically eg, bones that are anatomically

normal but biomechanically weak normal but biomechanically weak due to the age of the horse at the due to the age of the horse at the onset of training onset of training

or bone that is abnormally weak due or bone that is abnormally weak due to developmental orthopedic to developmental orthopedic disease), disease),

Inciting factors in lamenessInciting factors in lameness

direct or indirect trauma, direct or indirect trauma, incoordination of muscle action incoordination of muscle action

following fatigue in racehorses racing following fatigue in racehorses racing over long distances, over long distances,

or inflammationor inflammation——more often than more often than not without infectionnot without infection——of joints, of joints, tendons, and ligaments in particular. tendons, and ligaments in particular.

The Lameness Examination: The Lameness Examination: OverviewOverview

A systematic investigation of a lame A systematic investigation of a lame horse is time consuming. horse is time consuming.

The examination begins with a The examination begins with a comprehensive comprehensive medical historymedical history; type, age, ; type, age, and training regimen may give important and training regimen may give important clues to the lameness as will the time since clues to the lameness as will the time since onset of lameness and interim onset of lameness and interim management. management.

The interval since the last shoeing should The interval since the last shoeing should be noted, as well as any suggestions that be noted, as well as any suggestions that the lameness may improve with either rest the lameness may improve with either rest or exercise. or exercise.

Response to anti-inflammatory or analgesic Response to anti-inflammatory or analgesic medications may provide useful medications may provide useful information.information.

Results of hematologic and biochemical Results of hematologic and biochemical analyses may shed light on other problems analyses may shed light on other problems that influence overall performance. that influence overall performance.

detaileddetailed visual inspection visual inspection and thorough and thorough manual palpationmanual palpation of the limbs in of the limbs in weightbearing and nonweightbearing weightbearing and nonweightbearing positions.positions.

comparision with the contralateral limb comparision with the contralateral limb should always take place, should always take place,

Any heat, joint distention, or abnormal Any heat, joint distention, or abnormal tissue tension should be noted, as well as tissue tension should be noted, as well as the reaction of the horse and range of the reaction of the horse and range of flexion and extension of all joints. flexion and extension of all joints.

Specific areas of muscle wastage may also Specific areas of muscle wastage may also provide useful information. provide useful information.

The feetThe feet should be thoroughly should be thoroughly examined, including compression of examined, including compression of the walls and sole with hoof testers. the walls and sole with hoof testers.

Wear patterns of shoes and feet Wear patterns of shoes and feet should be noted. should be noted.

A number of abnormalities such as A number of abnormalities such as broken toe/pastern axis; mismatched broken toe/pastern axis; mismatched hoof angles; under-run, contracted, hoof angles; under-run, contracted, and sheared heels, and and sheared heels, and disproportionate hoof size are seen disproportionate hoof size are seen more frequently in lame than in more frequently in lame than in sound horses. sound horses.

Shoes should be left on, as Shoes should be left on, as removing them at this stage removing them at this stage might make the horse might make the horse footsore and thereby footsore and thereby preclude further examination.preclude further examination.

However, occasionally it may However, occasionally it may prove useful to remove the prove useful to remove the front shoes to demonstrate front shoes to demonstrate that the shoeing was the that the shoeing was the cause of the lameness. cause of the lameness.

    Hoof testers are applied across the hoof Hoof testers are applied across the hoof wall and the bottom of the hoof to check for wall and the bottom of the hoof to check for

painful areaspainful areas. .

The back and neckThe back and neck should be thoroughly should be thoroughly examined with the horse restrained and examined with the horse restrained and standing square on a level surface. standing square on a level surface.

The neck should be assessed for range of The neck should be assessed for range of movement in all planes and for evidence movement in all planes and for evidence of muscle asymmetry and pain. of muscle asymmetry and pain.

The dorsal midline of the back should be The dorsal midline of the back should be straight, and equal tone should be present straight, and equal tone should be present in the paravertebral musculature on either in the paravertebral musculature on either side of the midline.side of the midline.

The same should be true of the gluteal The same should be true of the gluteal musculature and the hamstrings. musculature and the hamstrings.

Spatial alignment of the tubera coxae and Spatial alignment of the tubera coxae and sacrale should also be observed. sacrale should also be observed.

Thorough palpation of the back is an Thorough palpation of the back is an important part of a lameness examinationimportant part of a lameness examination. .

Examination during exerciseExamination during exercise becomes an option only if the degree becomes an option only if the degree of lameness is minor and chronic. of lameness is minor and chronic.

If lameness is major and acute (eg, If lameness is major and acute (eg, suspected fracture), additional suspected fracture), additional exercise could result in a exercise could result in a catastrophic breakdown with dire catastrophic breakdown with dire consequences for the horse.consequences for the horse.

It is important to check whether the It is important to check whether the horse may have been given horse may have been given analgesic medication prior to the analgesic medication prior to the lameness examination. lameness examination.

Flexion testsFlexion tests are useful diagnostic are useful diagnostic tools. tools.

The range of movement and The range of movement and response to passive flexion, along response to passive flexion, along with any suggestion of increased with any suggestion of increased lameness or onset of lameness lameness or onset of lameness following flexion, should be following flexion, should be observed. observed.

However, results of recent studies However, results of recent studies have suggested that have suggested that ““false-positivefalse-positive”” results may be seen if excessive results may be seen if excessive forces are applied. forces are applied.

The horse's leg is held in a flexed position to The horse's leg is held in a flexed position to stress the joint.stress the joint.   The horse will be assessed The horse will be assessed

at a trot to determine if this flexion test at a trot to determine if this flexion test accentuates the lamenessaccentuates the lameness. .

A ridden assessmentA ridden assessment of the horse of the horse is often necessary, particularly with a is often necessary, particularly with a subtle lameness or a horse that is subtle lameness or a horse that is unwilling to perform certain unwilling to perform certain movements (eg, a dressage horse). A movements (eg, a dressage horse). A multilimb lameness without an multilimb lameness without an obvious single-limb lameness may obvious single-limb lameness may also be involved. The clinical signs also be involved. The clinical signs may be minor (eg, signs of aversion may be minor (eg, signs of aversion as opposed to lameness). as opposed to lameness).

Imaging TechniquesImaging Techniques Imaging techniques provide Imaging techniques provide

important pathologic and physiologic important pathologic and physiologic information necessary to treat information necessary to treat specific conditions.specific conditions.

Imaging can be divided into Imaging can be divided into anatomic and physiologic methods. anatomic and physiologic methods.

Anatomic imaging methods include Anatomic imaging methods include radiology, ultrasonography, radiology, ultrasonography, computed tomography, and MRI. computed tomography, and MRI.

Physiologic imaging methods include Physiologic imaging methods include scintigraphy and thermography. scintigraphy and thermography.

Anatomic Imaging TechniquesAnatomic Imaging Techniques Radiologic techniquesRadiologic techniques are the methods are the methods

most commonly used to evaluate lameness most commonly used to evaluate lameness in horses. Plain film radiography requires in horses. Plain film radiography requires multiple projections to evaluate any area. multiple projections to evaluate any area.

It allows assessment of bony tissues and It allows assessment of bony tissues and reflects chronic changes. Occasionally, reflects chronic changes. Occasionally, radiographic techniques that provide more radiographic techniques that provide more information are needed. information are needed.

Contrast radiography provides information Contrast radiography provides information about articular cartilage and surfaces and is about articular cartilage and surfaces and is of particular value in determining whether of particular value in determining whether subchondral cysts communicate with the subchondral cysts communicate with the joint and in delineating subcutaneous tracts. joint and in delineating subcutaneous tracts.

The technician holds an x-ray plate behind the The technician holds an x-ray plate behind the horse's limb so that a radiograph can be horse's limb so that a radiograph can be

taken.taken.   Some horses may need to be sedated Some horses may need to be sedated so they stand quietly for the x-rayso they stand quietly for the x-ray.  . 

Ultrasonographic examinationUltrasonographic examination can be used to assess any soft can be used to assess any soft tissues. tissues.

Ultrasonography is most useful in Ultrasonography is most useful in the evaluation of tendons and the evaluation of tendons and ligaments but can also be used to ligaments but can also be used to evaluate muscle and cartilage. evaluate muscle and cartilage.

It can also help determine whether a It can also help determine whether a lesion is active or chroniclesion is active or chronic. .

..MRI and computed tomography are MRI and computed tomography are high-detail anatomic imaging tools.high-detail anatomic imaging tools.

They are not currently used in They are not currently used in clinical practice but may be useful in clinical practice but may be useful in researchresearch..

This is an MRI of a horse with bone This is an MRI of a horse with bone inflammation in the front of the pastern inflammation in the front of the pastern

(light grey region) that could not be (light grey region) that could not be detected on radiographsdetected on radiographs. .

Physiologic Imaging Physiologic Imaging TechniquesTechniques

These techniques provide images These techniques provide images that reflect physiologic processes.that reflect physiologic processes.

Unlike anatomic imaging, which Unlike anatomic imaging, which reflects structure, physiologic reflects structure, physiologic imaging techniques assess imaging techniques assess metabolism or circulation. metabolism or circulation.

Thermography and scintigraphy Thermography and scintigraphy allow examination of the entire allow examination of the entire horse. horse.

ThermographyThermography is the pictorial representation is the pictorial representation of the surface temperature of an object. It is a of the surface temperature of an object. It is a noninvasive technique that measures emitted noninvasive technique that measures emitted heat and is useful for detecting inflammatory heat and is useful for detecting inflammatory changes that may contribute to lameness. changes that may contribute to lameness.

Thermographically, the Thermographically, the ““hot spothot spot”” associated associated with the localized inflammation generally is with the localized inflammation generally is seen in the skin directly overlying the injury. seen in the skin directly overlying the injury.

However, diseased tissues may have a However, diseased tissues may have a reduced blood supply due to swelling, vessel reduced blood supply due to swelling, vessel thrombosis, or tissue infarction. With such thrombosis, or tissue infarction. With such lesions, the area of decreased heat is usually lesions, the area of decreased heat is usually surrounded by increased thermal emissions, surrounded by increased thermal emissions, probably due to shunting of blood. probably due to shunting of blood.

During During scintigraphyscintigraphy, polyphosphonate , polyphosphonate radiopharmaceuticals are given IV. radiopharmaceuticals are given IV.

Their distribution is then measured by a Their distribution is then measured by a gamma camera.gamma camera.

The polyphosphonates bind rapidly to The polyphosphonates bind rapidly to exposed hydroxyapatite crystal, generally exposed hydroxyapatite crystal, generally in areas where bone is actively remodelling. in areas where bone is actively remodelling.

Because inflammation causes an increase Because inflammation causes an increase in blood flow, capillary permeability, and in blood flow, capillary permeability, and extracellular fluid volume, inflamed tissues extracellular fluid volume, inflamed tissues accumulate high levels of accumulate high levels of radiopharmaceutical during the soft-tissue radiopharmaceutical during the soft-tissue phase of scintigraphy, allowing evaluation phase of scintigraphy, allowing evaluation of soft-tissue injuries.of soft-tissue injuries.

During the bone phase, the During the bone phase, the radiopharmaceutical accumulates radiopharmaceutical accumulates in areas of increased remodelling or in areas of increased remodelling or vascularity.vascularity.

Because injured bone is Because injured bone is remodelled more rapidly, remodelled more rapidly, scintigraphy is useful for detecting scintigraphy is useful for detecting lesions in bone and ligaments, lesions in bone and ligaments, particularly in identifying particularly in identifying enthesopathy (damage to the enthesopathy (damage to the insertions of tendons and ligaments insertions of tendons and ligaments on bone). on bone).

ArthroscopyArthroscopy((Tenoscopy, BursoscopyTenoscopy, Bursoscopy))

ArthroscopyArthroscopy is the ultimate way of is the ultimate way of assessing the soft tissues of a joint. assessing the soft tissues of a joint.

It often combines diagnosis with It often combines diagnosis with therapy (surgery), with one procedure therapy (surgery), with one procedure often following the other during the often following the other during the same anesthetic procedure.same anesthetic procedure.

Arthroscopy provides the only option Arthroscopy provides the only option for examining all the soft tissues of the for examining all the soft tissues of the joint interior and enables minimally joint interior and enables minimally invasive surgical techniques, ensuring invasive surgical techniques, ensuring rapid healing of soft tissues, as only rapid healing of soft tissues, as only minute stab incisions are required. minute stab incisions are required.

It enables access to parts of joints not It enables access to parts of joints not accessible during an arthrotomy and accessible during an arthrotomy and allows for detailed magnified images allows for detailed magnified images to be stored and reproduced. to be stored and reproduced.

Arthroscopy also provides increased Arthroscopy also provides increased cosmetic and functional advantages cosmetic and functional advantages and has lower postsurgical morbidity, and has lower postsurgical morbidity, while decreasing convalescence time while decreasing convalescence time and ensuring an earlier return to work. and ensuring an earlier return to work.

It allows much improved mechanical It allows much improved mechanical lavage of joints (eg, use of 10-20 L of lavage of joints (eg, use of 10-20 L of saline under up to 300 mm Hg). saline under up to 300 mm Hg).

Most equine joints of the Most equine joints of the appendicular skeleton are large appendicular skeleton are large enough to allow arthroscopy enough to allow arthroscopy using a rigid endoscope of 2.5-using a rigid endoscope of 2.5-5 mm diameter, inserted 5 mm diameter, inserted through a rigid sleeve. through a rigid sleeve.

Camera attachments transmit Camera attachments transmit the images to a monitor from the images to a monitor from which still or video images can which still or video images can be obtained. be obtained.

Diagnostic and surgical Diagnostic and surgical tenoscopytenoscopy and and bursoscopybursoscopy are also used, often for cases are also used, often for cases of sepsis of synovial structures.of sepsis of synovial structures.

Bursoscopy of the navicular bursa has Bursoscopy of the navicular bursa has almost eliminated the almost eliminated the ““streetnail streetnail procedureprocedure”” for surgical treatment of sepsis, for surgical treatment of sepsis, as has calcaneal tenoscopy for infections as has calcaneal tenoscopy for infections that often follow kicks to the hock.that often follow kicks to the hock.

The minimal soft-tissue trauma described The minimal soft-tissue trauma described with tenoscopy is invaluable in restoring with tenoscopy is invaluable in restoring the normal intrasynovial environment and the normal intrasynovial environment and has revolutionized the recovery rate from has revolutionized the recovery rate from septic tenosynovitis. septic tenosynovitis.

Regional AnalgesiaRegional Analgesia

Diagnostic local analgesia is an Diagnostic local analgesia is an important component of the important component of the equine lameness examination if equine lameness examination if the site of pain is uncertain after the site of pain is uncertain after a thorough clinical examination.a thorough clinical examination.

The appendicular nervous The appendicular nervous system is quite consistent, and system is quite consistent, and there are few indications for there are few indications for ringblocks. ringblocks.

It should be used with care in horses It should be used with care in horses with severe lameness as, for with severe lameness as, for example, a simple fracture may example, a simple fracture may become comminuted if the protective become comminuted if the protective effect of pain is lost. effect of pain is lost.

Common conditions in which regional Common conditions in which regional analgesia is important in determining analgesia is important in determining an accurate diagnosis include an accurate diagnosis include superficial foot pain, navicular superficial foot pain, navicular disease, traumatic joint disease, and disease, traumatic joint disease, and proximal suspensory desmitis. proximal suspensory desmitis.

Perineural analgesia should Perineural analgesia should start distally and progress start distally and progress proximally. proximally.

Intrasynovial analgesia may Intrasynovial analgesia may start proximally if indicated start proximally if indicated by clinical findings, as this by clinical findings, as this does not preclude does not preclude subsequent distal subsequent distal analgesia. analgesia.

Nerves to a portion of the foot are blocked Nerves to a portion of the foot are blocked with a local anesthetic to see if the lameness with a local anesthetic to see if the lameness

resolvesresolves. .

Landmarks, forelimb nerve block, horseLandmarks, forelimb nerve block, horse

Anatomy for nerve block in medial arm Anatomy for nerve block in medial arm and forearm, horseand forearm, horse

Anatomy for nerve block of distal forelimb, Anatomy for nerve block of distal forelimb, horsehorse

Anatomy for nerve block, digital area, Anatomy for nerve block, digital area, forelimb, horseforelimb, horse

Landmarks, pelvic limb nerve block, Landmarks, pelvic limb nerve block, horsehorse

Anatomy for tarsus nerve block, horseAnatomy for tarsus nerve block, horse

Anatomy for lateral crus nerve block, Anatomy for lateral crus nerve block, horsehorse

Anatomy for medial crus nerve block, Anatomy for medial crus nerve block, horsehorse