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

Mechanical lameness is best typified by fibrotic myopathy with its characteristic gait abnormality, Mechanical lameness is best typified by fibrotic myopathy with its characteristic gait abnormality, but can also be the result of a restriction (eg, tendon sheath restriction in annular ligament syndrome). but can also be the result of a restriction (eg, tendon sheath restriction in annular ligament syndrome).

Pain-related lameness can be classified as: Pain-related lameness can be classified as: weightbearing (supporting leg) or weightbearing (supporting leg) or nonweightbearing (swinging leg) lameness, nonweightbearing (swinging leg) lameness, although lameness most often is composed of both. although lameness most often is composed of both.

A supporting leg lameness is seen when the horse attempts to reduce the amount of time a particular limb is bearing weight. A supporting leg lameness is seen when the horse attempts to reduce the amount of time a particular limb is bearing weight. The horse elevates its head and shifts its weight away from a particular limb during weightbearing for a forelimb lameness, whereas the opposite is true for a hindlimb lameness. The horse elevates its head and shifts its weight away from a particular limb during weightbearing for a forelimb lameness, whereas the opposite is true for a hindlimb lameness.

Factors that predispose to lameness physical immaturity : physical immaturity : eg, bones that are anatomically normal but biomechanically weak due to the age of the horse at the onset of training eg, bones that are anatomically normal but biomechanically weak due to the age of the horse at the onset of training or bone that is abnormally weak due to developmental orthopedic disease), or bone that is abnormally weak due to developmental orthopedic disease),

Inciting factors in lameness direct or indirect trauma, direct or indirect trauma, incoordination of muscle action following fatigue in racehorses racing over long distances, incoordination of muscle action following fatigue in racehorses racing over long distances, or inflammation — more often than not without infection — of joints, tendons, and ligaments in particular. or inflammation — more often than not without infection — of joints, tendons, and ligaments in particular.

The Lameness Examination: Overview A systematic investigation of a lame horse is time consuming. A systematic investigation of a lame horse is time consuming.

The examination begins with a comprehensive medical history; type, age, and training regimen may give important clues to the lameness as will the time since onset of lameness and interim management. The examination begins with a comprehensive medical history; type, age, and training regimen may give important clues to the lameness as will the time since onset of lameness and interim management. The interval since the last shoeing should be noted, as well as any suggestions that the lameness may improve with either rest or exercise. The interval since the last shoeing should be noted, as well as any suggestions that the lameness may improve with either rest or exercise. Response to anti-inflammatory or analgesic medications may provide useful information. Response to anti-inflammatory or analgesic medications may provide useful information. Results of hematologic and biochemical analyses may shed light on other problems that influence overall performance. Results of hematologic and biochemical analyses may shed light on other problems that influence overall performance.

detailed visual inspection and thorough manual palpation of the limbs in weightbearing and nonweightbearing positions. detailed visual inspection and thorough manual palpation of the limbs in weightbearing and nonweightbearing positions. comparision with the contralateral limb should always take place, comparision with the contralateral limb should always take place, Any heat, joint distention, or abnormal tissue tension should be noted, as well as the reaction of the horse and range of flexion and extension of all joints. Any heat, joint distention, or abnormal tissue tension should be noted, as well as the reaction of the horse and range of flexion and extension of all joints. Specific areas of muscle wastage may also provide useful information. Specific areas of muscle wastage may also provide useful information.

The feet should be thoroughly examined, including compression of the walls and sole with hoof testers. The feet should be thoroughly examined, including compression of the walls and sole with hoof testers. Wear patterns of shoes and feet should be noted. Wear patterns of shoes and feet should be noted. A number of abnormalities such as broken toe/pastern axis; mismatched hoof angles; under-run, contracted, and sheared heels, and disproportionate hoof size are seen more frequently in lame than in sound horses. A number of abnormalities such as broken toe/pastern axis; mismatched hoof angles; under-run, contracted, and sheared heels, and disproportionate hoof size are seen more frequently in lame than in sound horses.

Shoes should be left on, as removing them at this stage might make the horse footsore and thereby preclude further examination. Shoes should be left on, as removing them at this stage might make the horse footsore and thereby preclude further examination. However, occasionally it may prove useful to remove the front shoes to demonstrate that the shoeing was the cause of the lameness. However, occasionally it may prove useful to remove the front shoes to demonstrate that the shoeing was the cause of the lameness.

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

The back and neck should be thoroughly examined with the horse restrained and standing square on a level surface. The back and neck should be thoroughly examined with the horse restrained and standing square on a level surface. The neck should be assessed for range of movement in all planes and for evidence of muscle asymmetry and pain. The neck should be assessed for range of movement in all planes and for evidence of muscle asymmetry and pain. The dorsal midline of the back should be straight, and equal tone should be present in the paravertebral musculature on either side of the midline. The dorsal midline of the back should be straight, and equal tone should be present in the paravertebral musculature on either side of the midline. The same should be true of the gluteal musculature and the hamstrings. The same should be true of the gluteal musculature and the hamstrings. Spatial alignment of the tubera coxae and sacrale should also be observed. Spatial alignment of the tubera coxae and sacrale should also be observed.

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

Examination during exercise becomes an option only if the degree of lameness is minor and chronic. Examination during exercise becomes an option only if the degree of lameness is minor and chronic. If lameness is major and acute (eg, suspected fracture), additional exercise could result in a catastrophic breakdown with dire consequences for the horse. If lameness is major and acute (eg, suspected fracture), additional exercise could result in a catastrophic breakdown with dire consequences for the horse. It is important to check whether the horse may have been given analgesic medication prior to the lameness examination. It is important to check whether the horse may have been given analgesic medication prior to the lameness examination.

Flexion tests are useful diagnostic tools. Flexion tests are useful diagnostic tools. The range of movement and response to passive flexion, along with any suggestion of increased lameness or onset of lameness following flexion, should be observed. The range of movement and response to passive flexion, along with any suggestion of increased lameness or onset of lameness following flexion, should be observed. However, results of recent studies have suggested that “ false-positive ” results may be seen if excessive forces are applied. However, results of recent studies have suggested that “ false-positive ” results may be seen if excessive forces are applied.

The horse's leg is held in a flexed position to stress the joint. The horse will be assessed at a trot to determine if this flexion test accentuates the lameness.

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

Imaging Techniques Imaging techniques provide important pathologic and physiologic information necessary to treat specific conditions. Imaging techniques provide important pathologic and physiologic information necessary to treat specific conditions. Imaging can be divided into anatomic and physiologic methods. Imaging can be divided into anatomic and physiologic methods. Anatomic imaging methods include radiology, ultrasonography, computed tomography, and MRI. Anatomic imaging methods include radiology, ultrasonography, computed tomography, and MRI. Physiologic imaging methods include scintigraphy and thermography. Physiologic imaging methods include scintigraphy and thermography.

Anatomic Imaging Techniques Radiologic techniques are the methods most commonly used to evaluate lameness in horses. Plain film radiography requires multiple projections to evaluate any area. Radiologic techniques are the methods most commonly used to evaluate lameness in horses. Plain film radiography requires multiple projections to evaluate any area. It allows assessment of bony tissues and reflects chronic changes. Occasionally, radiographic techniques that provide more information are needed. It allows assessment of bony tissues and reflects chronic changes. Occasionally, radiographic techniques that provide more information are needed. Contrast radiography provides information about articular cartilage and surfaces and is of particular value in determining whether subchondral cysts communicate with the joint and in delineating subcutaneous tracts. Contrast radiography provides information about articular cartilage and surfaces and is of particular value in determining whether subchondral cysts communicate with the joint and in delineating subcutaneous tracts.

The technician holds an x-ray plate behind the horse's limb so that a radiograph can be taken. Some horses may need to be sedated so they stand quietly for the x-ray. The technician holds an x-ray plate behind the horse's limb so that a radiograph can be taken. Some horses may need to be sedated so they stand quietly for the x-ray.

Ultrasonographic examination can be used to assess any soft tissues. Ultrasonographic examination can be used to assess any soft tissues. Ultrasonography is most useful in the evaluation of tendons and ligaments but can also be used to evaluate muscle and cartilage. Ultrasonography is most useful in the evaluation of tendons and ligaments but can also be used to evaluate muscle and cartilage. It can also help determine whether a lesion is active or chronic. It can also help determine whether a lesion is active or chronic.

.MRI and computed tomography are high- detail anatomic imaging tools..MRI and computed tomography are high- detail anatomic imaging tools. They are not currently used in clinical practice but may be useful in research. They are not currently used in clinical practice but may be useful in research.

This is an MRI of a horse with bone inflammation in the front of the pastern (light grey region) that could not be detected on radiographs.

Physiologic Imaging Techniques These techniques provide images that reflect physiologic processes. These techniques provide images that reflect physiologic processes. Unlike anatomic imaging, which reflects structure, physiologic imaging techniques assess metabolism or circulation. Unlike anatomic imaging, which reflects structure, physiologic imaging techniques assess metabolism or circulation. Thermography and scintigraphy allow examination of the entire horse. Thermography and scintigraphy allow examination of the entire horse.

Thermography is the pictorial representation of the surface temperature of an object. It is a noninvasive technique that measures emitted heat and is useful for detecting inflammatory changes that may contribute to lameness. Thermography is the pictorial representation of the surface temperature of an object. It is a noninvasive technique that measures emitted heat and is useful for detecting inflammatory changes that may contribute to lameness. Thermographically, the “ hot spot ” associated with the localized inflammation generally is seen in the skin directly overlying the injury. Thermographically, the “ hot spot ” associated with the localized inflammation generally is seen in the skin directly overlying the injury. However, diseased tissues may have a reduced blood supply due to swelling, vessel thrombosis, or tissue infarction. With such lesions, the area of decreased heat is usually surrounded by increased thermal emissions, probably due to shunting of blood. However, diseased tissues may have a reduced blood supply due to swelling, vessel thrombosis, or tissue infarction. With such lesions, the area of decreased heat is usually surrounded by increased thermal emissions, probably due to shunting of blood.

During scintigraphy, polyphosphonate radiopharmaceuticals are given IV. During scintigraphy, polyphosphonate radiopharmaceuticals are given IV. Their distribution is then measured by a gamma camera. Their distribution is then measured by a gamma camera. The polyphosphonates bind rapidly to exposed hydroxyapatite crystal, generally in areas where bone is actively remodelling. The polyphosphonates bind rapidly to exposed hydroxyapatite crystal, generally in areas where bone is actively remodelling. Because inflammation causes an increase in blood flow, capillary permeability, and extracellular fluid volume, inflamed tissues accumulate high levels of radiopharmaceutical during the soft-tissue phase of scintigraphy, allowing evaluation of soft-tissue injuries. Because inflammation causes an increase in blood flow, capillary permeability, and extracellular fluid volume, inflamed tissues accumulate high levels of radiopharmaceutical during the soft-tissue phase of scintigraphy, allowing evaluation of soft-tissue injuries.

During the bone phase, the radiopharmaceutical accumulates in areas of increased remodelling or vascularity. During the bone phase, the radiopharmaceutical accumulates in areas of increased remodelling or vascularity. Because injured bone is remodelled more rapidly, scintigraphy is useful for detecting lesions in bone and ligaments, particularly in identifying enthesopathy (damage to the insertions of tendons and ligaments on bone). Because injured bone is remodelled more rapidly, scintigraphy is useful for detecting lesions in bone and ligaments, particularly in identifying enthesopathy (damage to the insertions of tendons and ligaments on bone).

Arthroscopy (Tenoscopy, Bursoscopy) Arthroscopy is the ultimate way of assessing the soft tissues of a joint. Arthroscopy is the ultimate way of assessing the soft tissues of a joint. It often combines diagnosis with therapy (surgery), with one procedure often following the other during the same anesthetic procedure. It often combines diagnosis with therapy (surgery), with one procedure often following the other during the same anesthetic procedure. Arthroscopy provides the only option for examining all the soft tissues of the joint interior and enables minimally invasive surgical techniques, ensuring rapid healing of soft tissues, as only minute stab incisions are required. Arthroscopy provides the only option for examining all the soft tissues of the joint interior and enables minimally invasive surgical techniques, ensuring rapid healing of soft tissues, as only minute stab incisions are required.

It enables access to parts of joints not accessible during an arthrotomy and allows for detailed magnified images to be stored and reproduced. It enables access to parts of joints not accessible during an arthrotomy and allows for detailed magnified images to be stored and reproduced. Arthroscopy also provides increased cosmetic and functional advantages and has lower postsurgical morbidity, while decreasing convalescence time and ensuring an earlier return to work. Arthroscopy also provides increased cosmetic and functional advantages and has lower postsurgical morbidity, while decreasing convalescence time and ensuring an earlier return to work. It allows much improved mechanical lavage of joints (eg, use of L of saline under up to 300 mm Hg). It allows much improved mechanical lavage of joints (eg, use of L of saline under up to 300 mm Hg).

Most equine joints of the appendicular skeleton are large enough to allow arthroscopy using a rigid endoscope of mm diameter, inserted through a rigid sleeve. Most equine joints of the appendicular skeleton are large enough to allow arthroscopy using a rigid endoscope of mm diameter, inserted through a rigid sleeve. Camera attachments transmit the images to a monitor from which still or video images can be obtained. Camera attachments transmit the images to a monitor from which still or video images can be obtained.

Diagnostic and surgical tenoscopy and bursoscopy are also used, often for cases of sepsis of synovial structures. Diagnostic and surgical tenoscopy and bursoscopy are also used, often for cases of sepsis of synovial structures. Bursoscopy of the navicular bursa has almost eliminated the “ streetnail procedure ” for surgical treatment of sepsis, as has calcaneal tenoscopy for infections that often follow kicks to the hock. Bursoscopy of the navicular bursa has almost eliminated the “ streetnail procedure ” for surgical treatment of sepsis, as has calcaneal tenoscopy for infections that often follow kicks to the hock. The minimal soft-tissue trauma described with tenoscopy is invaluable in restoring the normal intrasynovial environment and has revolutionized the recovery rate from septic tenosynovitis. The minimal soft-tissue trauma described with tenoscopy is invaluable in restoring the normal intrasynovial environment and has revolutionized the recovery rate from septic tenosynovitis.

Regional Analgesia Diagnostic local analgesia is an important component of the equine lameness examination if the site of pain is uncertain after a thorough clinical examination. Diagnostic local analgesia is an important component of the equine lameness examination if the site of pain is uncertain after a thorough clinical examination. The appendicular nervous system is quite consistent, and there are few indications for ringblocks. The appendicular nervous system is quite consistent, and there are few indications for ringblocks.

It should be used with care in horses with severe lameness as, for example, a simple fracture may become comminuted if the protective effect of pain is lost. It should be used with care in horses with severe lameness as, for example, a simple fracture may become comminuted if the protective effect of pain is lost. Common conditions in which regional analgesia is important in determining an accurate diagnosis include superficial foot pain, navicular disease, traumatic joint disease, and proximal suspensory desmitis. Common conditions in which regional analgesia is important in determining an accurate diagnosis include superficial foot pain, navicular disease, traumatic joint disease, and proximal suspensory desmitis.

Perineural analgesia should start distally and progress proximally. Perineural analgesia should start distally and progress proximally. Intrasynovial analgesia may start proximally if indicated by clinical findings, as this does not preclude subsequent distal analgesia. Intrasynovial analgesia may start proximally if indicated by clinical findings, as this does not preclude subsequent distal analgesia.

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

Landmarks, forelimb nerve block, horse

Anatomy for nerve block in medial arm and forearm, horse

Anatomy for nerve block of distal forelimb, horse

Anatomy for nerve block, digital area, forelimb, horse

Landmarks, pelvic limb nerve block, horse

Anatomy for tarsus nerve block, horse

Anatomy for lateral crus nerve block, horse

Anatomy for medial crus nerve block, horse