Chiropractic Evaluation and Management of Musculoskeletal Disorders

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Chiropractic Evaluation and Management of Musculoskeletal Disorders Kevin K. Haussler MANUAL THERAPY AND CHIROPRACTIC

References on page 1333

Manual therapy involves the application of the hands directly to the body, with the goal of treating soft tissue injuries or articular dysfunction. Chiropractic, osteopathy, massage therapy, therapeutic touch, and certain physical therapy techniques are considered forms of manual therapy. Chiropractic is a health profession concerned with the diagnosis, treatment, and prevention of disorders of the musculoskeletal system and the effects of these disorders on the nervous system and general health.1 The word chiropractic is derived from the Greek words cheir, meaning “hand,” and praktikos, meaning “concerning action.” The goal of chiropractic is to optimize health through the inherent healing ability of the body (i.e., homeostasis) as affected by and integrated through the nervous system.2 The practice of chiropractic focuses on the relationship between structure (primarily the spinal column) and function (as coordinated by the nervous system) and how that relationship affects the preservation and restoration of health. Chiropractic uses controlled forces (i.e., adjustments), which are applied to specific joints or anatomical regions, to induce therapeutic responses through induced changes in joint structures, muscle function, and neurological reflexes. Research in people demonstrated reductions in pain and muscle hypertonicity and increased joint range of motion after chiropractic treatment.2,3 Joint mobilization and manipulation are two types of induced articular movements used in musculoskeletal rehabilitation to restore joint function. Mobilization is characterized as repetitive joint movements induced within the normal physiological range of joint motion (Figure 93-1). Joint manipulation (e.g., chiropractic adjustment) occurs within the paraphysiological zone, which lies outside of the active (i.e., patient induced) and passive ranges of joint

motion. In people, joint mobilization and manipulation induce different physiological responses. Manipulation in people relieved adjacent spontaneous myoelectrical activity immediately, whereas mobilization did not.2

PRACTITIONER QUALIFICATIONS Equine practitioners have seen a proliferation in the use of chiropractic techniques on horses, in one form or another. Veterinarians currently do not receive any formal education in chiropractic principles or techniques; therefore many equine clinicians do not have a basic understanding of chiropractic principles or clinical applications. Conversely, chiropractors (doctors of chiropractic) do not have any formal training in comparative anatomy, physiology, or pathology or clinical equine experience. Veterinary medicine, for the most part, has been forced to acknowledge the use of chiropractic and other nontraditional modalities by horse owners who have sought practitioners who use these techniques and have experienced their perceived therapeutic effects.4 However, limited research has been done to evaluate the clinical effectiveness of chiropractic techniques in horses. If veterinarians have not taken the time or made the effort to learn more about these nontraditional techniques, objectively evaluating the use of chiropractic, discussing the indications or contraindications for a specific treatment modality, or applying these techniques clinically is difficult. Therefore owners often seek advice about alternative therapies or treatment from

Physiological zone Paraphysiological zone

Elastic barrier Anatomical limit

Pathological zone

Fig. 93-1  •  Schematic representation of the three articular zones of joint motion: physiological, paraphysiological, and pathological. The elastic barrier and the anatomical limit mark the transitional boundaries among the three articular zones.

Chapter 93  Chiropractic Evaluation and Management of Musculoskeletal Disorders someone who is not their regular veterinarian and often without his or her knowledge. To complicate matters, many laypersons claiming to be equine chiropractors are not professionally trained or licensed in chiropractic or veterinary medicine. These lay practitioners often have a limited knowledge of equine musculoskeletal anatomy, physiology, biomechanics, and pathology. Because of the potential misapplication, chiropractic evaluation and treatment should be provided only by licensed professionals (i.e., veterinarians or chiropractors working under the direct supervision of a veterinarian) who have pursued additional postgraduate training in animal chiropractic principles and techniques. The primary organizations in North America currently involved in training and certifying veterinarians and chiropractors in animal chiropractic are Options for Animals, based in Wellsville, Kansas; Parker College of Chiropractic in Dallas, Texas; and the Healing Oasis Wellness Center in Sturtevant, Wisconsin and in Canada. An additional course on equine osteopathy is offered at the Vluggen Institute in San Marcos, Texas. Equine manual therapy courses in Europe include Focus on the Equine Spine in the Netherlands; McTimoney College of Chiropractic in England; the International Academy of Veterinary Chiropractic in both Germany and England; and a Healing Oasis Wellness Center–sponsored course in Germany. Most state chiropractic and veterinary medical boards do not allow chiropractors to treat animals unless they are working under the direct supervision of a veterinarian. This requires that the veterinarian and chiropractor work together in evaluating and treating the horse and provide appropriate follow-up care as indicated. It is strongly recommended that owners and referring veterinarians seek out licensed professionals (veterinarians or chiropractors) who have had specialized training and experience in chiropractic evaluation and treatment of horses. Veterinarians who have not pursued formal postgraduate training are not qualified to provide chiropractic care and risk producing more harm than potential benefit. It is a good idea to ask equine chiropractors about their professional and postgraduate training or certification, horse experience, and the types of techniques that they use (i.e., hands only versus more aggressive techniques, or the use of additional instruments). Chiropractic and osteopathy require a working knowledge and understanding of vertebral anatomy, physiology, biomechanics, pathology, and rehabilitation. Combining the knowledge and expertise of the veterinary and chiropractic professions provides practitioners with new insights and methods for diagnosing and managing horses with select vertebral or musculoskeletal disorders. A similar multidisciplinary approach has developed in human medicine in the last 20 years to address chronic pain syndromes and vertebral column disorders.

HISTORY OF EQUINE CHIROPRACTIC Chiropractors often have been asked to treat the horses of clients who have experienced the benefits of chiropractic care for their own back or neck problems. Horse owners often want the opportunity to have the same type of care for their horses, without the potential adverse effects of medications or surgery. The recent increased awareness of the prevalence and management options to address back problems with which traditional veterinary medicine has

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had difficulty in dealing has also stimulated horse owners’ interest in complementary forms of treatment.5 Any vertebral column disorder can have serious effects on a horse’s ability to perform. Back problems can be classified into three basic types of injuries—those involving the muscles, tendons, and ligaments (soft tissue injuries); bones and joints (osseous injuries); or nervous system (neurological disorders). However, several concurrent injuries have been reported in 17% of horses with back pain.6 Diagnosis of the underlying vertebral pathological conditions in horses with back pain is important for the appropriate treatment and management of these disorders (see Chapter 52). Many horses in which chiropractic may be useful often have a history of a traumatic event or an injury related to overexertion.7 Trauma may occur as a single event (i.e., macrotrauma), such as a trailer accident, flipping over backward, or substantial falls over jumps. Severe musculoskeletal injuries may improve gradually, but they never resolve totally, or debilitating arthritis or soft tissue fibrosis may subsequently develop. Chronic overuse injuries (i.e., microtrauma) usually are associated with poor saddle fit, improper riding techniques, inadequate shoeing, or faulty conformation. Long periods of confinement, inconsistent training programs, or cumulative stresses and strains related to prolonged, high-level athletic activities also may predispose horses to musculoskeletal injuries and reduced performance. Older horses, like elderly people, are susceptible to loss of vertebral column flexibility, joint degeneration, and loss of muscle strength. Aged horses also have increased healing times and increased chances of having chronic conditions or abnormal musculoskeletal compensations from prior injuries. Chiropractic techniques have helped identify and treat some of these previously undiagnosed or poorly managed problems in horses. Most veterinarians use chiropractic techniques to complement their conventional veterinary practice.

COMPLEMENTARY APPROACHES Prevalence of back problems in horses varies greatly (from 0.9% to 94%), depending on the specialization or type of practice surveyed: general practice, 0.9%; Thoroughbred racehorse practice, 2%; veterinary school referrals, 5%; mixed equine practice including dressage, show jumpers, and eventing, 13%; spinal research clinic, 47%; and equine chiropractic clinic, 94%.8 Clinicians often have difficulties when dealing with horses with no obvious localized pain or vague, unspecified lameness. Neck or back problems and limb injuries often are interrelated. Distal limb injuries can cause an alteration in carriage of the affected limb and altered gait, which subsequently can overwork or injure proximal limb musculature and the paraspinal musculature. Similarly, vertebral column injuries can produce gait abnormalities, increased concussive forces, and distal limb lameness. The diagnostic dilemma facing clinicians is to decide whether the limb or the vertebral column is the primary or initial cause of the horse’s clinical problem. Unless the primary cause of the neck or back pain is identified and treated, most horses will have recurrent back pain when returned to work after a period of rest or a trial of antiinflammatory medications. Nonspecific back pain most likely is related to a functional impairment and not a structural disorder. Therefore many back problems may

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PART IX  Therapeutics

be related to muscle or joint dysfunction, with secondary soft tissue irritation and pain generation.9 Chiropractic provides expertise in evaluating vertebral column disorders and can provide an additional means of diagnosis and early treatment options in certain types of gait abnormalities or performance problems. Prepurchase examinations using chiropractic examination techniques can help identify horses that have chronic underlying neck or back problems.7 Chiropractic addresses subclinical conditions or abnormal biomechanics, which may progress to future debilitating musculoskeletal injuries. Chiropractors are trained in using physiotherapy modalities, strength training exercises, massage, stretching techniques, and other forms of musculoskeletal and nerve rehabilitation. Equine chiropractic is a complementary modality that can be used in veterinary medicine for the diagnosis, treatment, and potential prevention of select musculoskeletal disorders in horses. However, although a few recent studies have investigated the short-term effectiveness of chiro­ practic intervention in the horse, none have addressed performance benefits, long-term efficacy, and the safety or cost-effectiveness of chiropractic procedures in equine veterinary medicine.

PATHOPHYSIOLOGY AND MECHANISMS OF ACTION The vertebral motion segment is the functional unit of the vertebral column and includes two adjacent vertebrae and the associated soft tissues that bind them together. The basic elements of joint dysfunction include altered articular neurophysiology, biochemical alterations, pathological conditions of the joint capsule, and articular degeneration.2,3 Vertebral segment dysfunction (i.e., chiropractically defined subluxation) is a vertebral lesion characterized by the following: 1. Asymmetrical or loss of normal joint motion (Figure 93-2) 2. Diminished pain thresholds to pressure in the adjacent paraspinal tissues or osseous structures 3. Abnormal paraspinal muscle tension 4. Visual or palpatory signs of active inflammation or chronic tissue texture abnormalities (e.g., edema, fibrosis, hyperemia, or altered temperature)2 Numerous theories have been proposed and tested over the years to explain the causes of vertebral segment dysfunction in people and its effects on the neuromuscu­ loskeletal system.2,3 The chiropractically defined vertebral

subluxation complex is a theoretical model that incorporates the complex mechanical and biochemical interactions of injured nervous, muscular, articular, ligamentous, vascular, and connective tissues.10 The theory of a “bone out of place” is outdated and not supported by current spinal research in people. The goal of chiropractic treatment is to reduce pain and muscle hypertonicity, restore joint motion, and stimulate neurological reflexes. The exact mechanisms by which chiropractic techniques produce therapeutic effects are not certain. Chiropractic treatment may reduce musculoskeletal pain by stimulating nociceptive reflexes and release of neuropeptides (i.e., endorphins and enkephalins).2,11,12 Concurrent muscle spasms restrict joint motion and may contribute to the further development of joint stiffness. In people, palpatory changes in osseous symmetry after manipulation often are associated with soft tissue alterations and not actual reduction of an articular misalignment.9 Chiropractic care can improve restricted joint motion and may reduce the associated harmful effects of joint immobilization.2,3 In response to chronic pain or stiffness, new movement patterns are learned by the nervous system and adopted in an attempt to reduce pain or discomfort. Long after the initial injury has healed, adaptive or secondary movement patterns that predispose additional joints or muscles to injury may persist.9 Chiropractic treatment is thought to affect mechanoreceptors (i.e., Golgi tendon organ and muscle spindles) to induce reflex inhibition of pain and reflex muscle relaxation and to correct abnormal movement patterns.10,12 Additional modalities used to address altered movement patterns in people and horses include stretching or relaxing hypertonic muscles, strengthening weak muscles, and reeducating movement patterns.9 Successful chiropractic treatment requires specific techniques and psychomotor skills.3 A thorough knowledge of vertebral anatomy and joint biomechanics is required for proper chiropractic evaluation and treatment. Joint manipulation often induces a palpable release or movement of the restricted articulations. An audible cracking or popping also may be heard during chiropractic treatment as the applied force overcomes the elastic barrier of joint resistance.13,14 The rapid articular separation produces a cavitation of the synovial fluid.15 Radiological studies of synovial articulations after manipulation in people have shown a radiolucent cavity within the joint space (i.e., vacuum phenomenon) that contains 80% carbon dioxide and lasts for 15 to 20 minutes. A second attempt to recavitate the joint will be unsuccessful and potentially painful until the intraarticular gas is reabsorbed (i.e., refractory period).

EQUINE CHIROPRACTIC RESEARCH

Normal joint mobility

Symmetrical hypomobility

Asymmetrical hypomobility

Fig. 93-2  •  Diagram of patterns of normal and altered joint range of motion. Symmetrical joint hypomobility is characterized by generalized stiffness. Asymmetrical joint hypomobility is characterized by reduced joint mobility in one or more directions (e.g., left lateral bending).

The focus of recent equine manual therapy research has been on assessing the clinical effects of chiropractic techniques on relieving pain, improving flexibility, and restoring spinal motion symmetry. A veterinarian’s ability to physically induce movement in a horse’s back has been questioned. Pilot work in three horses that were instrumented with spinal transducers attached to Steinman pins implanted into dorsal spinous processes at adjacent vertebrae demonstrated that manually applied forces associated

Chapter 93  Chiropractic Evaluation and Management of Musculoskeletal Disorders with chiropractic techniques were able to produce sub­ stantial segmental spinal motion.16 The induced spinal motions were usually beyond the normal range of segmental motion that was measured during treadmill locomotion (up to 227% larger segmental spinal range of motion induced by high-velocity, low-amplitude thrusts than measured at the walk). The next logical research question would be what, if any, are the therapeutic effects of these induced spinal movements? In two randomized, controlled clinical trials, pressure algometry was used to measure mechanical nociceptive thresholds (MNTs) in the thoracolumbar region and to evaluate whether chiropractic treatment can reduce back pain (or increase MNTs) relative to findings in a control group of horses.17,18 The first study evaluated 24 horses in active exercise, with the treatment group receiving high-velocity, low-amplitude thrusts applied to the thirteenth thoracic vertebra (T13) to the sixth lumbar vertebra (L6) region.17 At 2 weeks, 21 of 29 (72%) treated sites had increased MNTs, six (21%) sites had decreased MNTs, and two (7%) sites had similar MNTs. Although MNTs in all 10 treated sites within the T13 to L6 region increased, magnitude was significant in only 7 (24%) sites when compared with the control group. In the second study 38 horses without previously recognized clinical signs of back pain were randomly divided into five treatment groups with MNTs measured at seven bilateral sites at the T9 to second sacral (S2) vertebral levels.18 Single applications of instrument-assisted (Activator) high-velocity, low-amplitude thrusts and massage therapy were given at day 0 in two groups at sites of pain, muscle hypertonicity, or stiffness. Phenylbutazone was given orally at a dose of 2 g twice a day for 7 days in the third group, and active and inactive horses were assigned to two control groups. MNTs were measured at Days 0, 1, 3, and 7. The Day 7 median MNTs had increased by 27% in the chiropractic group, 12% in the massage therapy group, and 8% in the phenylbutazone group, with less than 1% changes in both control groups.18 Future research is recommended to evaluate long-term effects and the potential synergistic effects of combined therapies (e.g., chiropractic and massage therapy) for treating back pain. Additional studies assessed the effects of equine chiropractic techniques on passive spinal mobility (i.e., flexibility) and longissimus muscle tone.19,20 The first study used 10 horses to objectively measure vertical displacement, applied force, and stiffness at five thoracolumbar intervertebral sites in an experimentally induced back pain model using a randomized, crossover study design.19 The chiropractic treatment induced a 15% increase in vertical displacement and a 20% increase in applied force, compared with control measurements, indicative of increased spinal flexibility and increased tolerance to applied pressure. The second study measured changes in muscle tone and electromyographic (EMG) activity within the longissimus muscle immediately after spinal manipulation or reflex inhibition therapy, compared with a control group.20 Significant decreases in muscle tone and EMG activity were measured in both treatment groups, compared with no significant changes within the control group. Additional studies are needed to determine how long the increased flexibility and reduced muscle tone persist in horses treated with chiropractic techniques and whether these therapies can improve performance.

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The last two studies document the potential beneficial effects of chiropractic treatment on spinal movement patterns in horses with documented back pain.21,22 In a dressage horse with back pain and severe loss of performance, objective spinal kinematic assessment was performed before and up to 8 months after the last chiropractic treatment.21 A right lateral bending restriction (functional scoliosis) was diagnosed, and two high-velocity, low-amplitude treatments were applied, 3 weeks apart. Symmetry of spinal movement indices improved dramatically after the first chiropractic treatment and remained improved above baseline at 8 months after the last treatment. It was concluded that manipulation had a measurable influence on kine­ matics of the thoracolumbar spine; however, this improvement was not judged equivalent to clinical improvement. A follow-up study assessed limb and spinal kinematics before and 1 hour and 3 weeks after chiropractic treatment in 10 horses.22 Significant changes in spinal kinematics were noted at the walk and trot, but no changes were noted in limb kinematics. The main overall effect was more thoracic region flexion, a reduced inclination of the pelvis, and improvement of the symmetry of the pelvic motion pattern. It was concluded that chiropractic treatment elicited slight but clinically significant changes in thoracolumbar and pelvic kinematics and that changes may be beneficial.

CLINICAL EVALUATION Chiropractic, like any medical evaluation, begins with a thorough history, discussion of the chief complaint, and observation of the horse from a distance for conformation, posture, and signs of lameness. Chiropractic evaluation and treatment are not a substitute for a thorough lameness examination and diagnostic workup, because many horses have musculoskeletal conditions that are identified readily and managed with traditional approaches. In veterinary medicine, many structural abnormalities of the vertebral column are becoming easier to diagnose with newer imaging modalities (e.g., scintigraphy and ultrasonography). Currently most clinicians are not well educated or experienced in procedures required to perform a thorough functional evaluation of the equine vertebral column. Therefore horses with conditions not diagnosed readily using traditional modalities, or with suspected concurrent neck or back problems, may require referral for chiropractic evaluation. Horses with conditions that may be responsive to chiropractic care have a variety of nonspecific or vague problems (Box 93-1). The focus of the chiropractic examination is placed on evaluating static and dynamic characteristics of the musculoskeletal system. Initially the horse’s general attitude and behavior are monitored for signs of pain or discomfort. Vertebral column conformation then is evaluated for proper alignment and symmetry, with special attention to the top line, shape and height of the withers, and osseous pelvic symmetry. A short-coupled horse is thought to have a higher incidence of osseous disorders, whereas a long-backed horse is more prone to soft tissue injuries.23 Conformation is a structural relationship of body segments, whereas postural analysis deals more with functional relationships. The horse is made to stand on a hard, level surface and is evaluated for a preferred or shifting

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PART IX  Therapeutics BOX 93-1 

Potential Clinical Indications for Chiropractic Evaluation and Treatment of Horses Poor performance Back or neck pain Reduced neck or back flexibility Not able to raise or lower head and neck Localized muscle tightness Vague lameness Uneven or asymmetrical gait Recent change in spinal conformation Difficult or improper saddle fit Discomfort with saddle placement Resentment of tightening of the cinch or girth Stiff and slow to warm up Bucking or pinning ears when ridden Lame only when ridden Constantly on one rein or line Difficulty with a lead or gait transition Refusing jumps Resisting collection Difficulty with turning in one direction Consistent stumbling or toe dragging Muscle mass asymmetry Pelvic asymmetry Not standing squarely on all limbs Difficulty standing for the farrier Holding tail to one side Resentment of being groomed Behavior or avoidance problem Modified from Willoughby SL: Equine chiropractic care, Port Byron, IL, United States, 1991, Options for Animals Foundation.

stance, head and neck carriage, vertebral curvatures, and muscular symmetry. Chiropractic gait analysis focuses on evaluating regional vertebral mobility and pelvic motion symmetry, in addition to the typical assessment of forelimb and hindlimb lameness. Gait analysis may help to rule out distal limb disorders and to rule in vertebral dysfunction, although limb lameness has been reported in about 85% of horses with back problems.24 Motion asymmetries, restricted vertebral or pelvic mobility, not tracking straight, and lack of propulsion are a few characteristics that are evaluated. Tape on the tubera coxae or vertebral column midline may make subtle motion asymmetries easier to see. Normal vertebral column motion consists of small cumulative amounts of segmental motion, which produce an overall smooth curve or movement of the vertebral column (Figure 93-3). Evaluation of the horse’s response to having a saddle placed and being ridden is important for a complete assessment of horses with back problems. Inspection of the tack for proper use and fit is always suggested on initial examination. Saddles and restraint devices should be evaluated for proper fit, padding, and positioning on the horse. A thorough physical examination is used to eliminate other, more common causes of lameness or neurological disorders. Chiropractic evaluation focuses on evaluating and localizing segmental vertebral dysfunction, which is

Fig. 93-3  •  Diagram of normal segmental vertebral contributions to overall vertebral column mobility during active left and right lateral bending. Note the smooth vertebral curve produced by cumulative segmental joint motion.

characterized by localized pain, muscle hypertonicity, and reduced joint motion.10 Palpation is used to localize and identify soft tissue and osseous structures for changes in texture, tissue mobility, or resistance to pressure.23,25 Soft tissue layers are evaluated from superficial to deep in two ways: by increasing digital pressure and by shifting attention with discrete palpatory movements. Shapes of structures, transitions between structures, and attachment sites also may be palpated.9 Soft tissue texture and mobility can be compared among the skin, subcutaneous tissue, thoracolumbar fascia, and muscle. Response to palpation is important, especially in evaluating tenderness or hypersensitivity. Osseous palpation involves evaluating osseous structures for pain, morphology, asymmetries, and alignment. Many horses with dental problems or malocclusion have localized pain during palpation of the temporomandibular joints and hypertonicity of the adjacent muscles of mastication. Osseous asymmetry of the space between the ramus of the mandible and the lateral wing of the atlas (first cervical vertebra) can be identified in horses with upper cervical congenital malformations, in horses with poll trauma caused by pulling back or falling over, or in some horses that head toss. Such asymmetry can also be seen in some otherwise clinically normal horses. The apices of the thoracic and lumbar spinous processes are readily palpable in most horses, unless they are grossly overweight. The dorsal apices of individual spinous processes are palpated with firm manual pressure, while monitoring for a localized pain response or muscle hypertonicity, indicative of local injury or impinged spinous processes. Palpable deviations of individual spinous processes are common, but usually they are not associated with spinous process fracture or vertebral malposition (i.e., bone out of place), as is commonly thought. Overlapping or malaligned dorsal spinous processes are often caused by spinous process impingement, developmental asymmetries in the neural arch, or isolated dorsal spinous process deviation of unknown cause.5,26 During induced kyphosis, the abaxial borders of each individual thoracolumbar spinous process and the overlying supraspinous ligament are palpated for pain, thickening, or deviation from midline. The tubera sacrale are palpated for height asymmetries and evaluated for a localized pain response to manual pressure applied dorsally or during abaxial compression. The apices of the sacral spinous processes (of the second to fifth sacral vertebrae) are palpated for pain or deviation from midline.

Chapter 93  Chiropractic Evaluation and Management of Musculoskeletal Disorders

A

B

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C

Fig. 93-4  •  Diagram of segmental vertebral motion during manually induced left lateral bending of the vertebral column. Arrows indicate direction of applied forces to vertebral column. A, Normal segmental motion of the vertebral column. B, Locally restricted vertebral motion involving two vertebrae. C, Regionally restricted vertebral motion involving several vertebrae.

A complete musculoskeletal examination includes assessment of active and passive ranges of joint motion for all axial and appendicular articulations. Active joint range of motion is evaluated during induced vertebral movements (carrot stretches) and gait analysis. Assessment of passive range of motion requires muscular relaxation as the articulations are moved passively throughout the individual joint ranges of motion (Figure 93-4). Abnormal segmental vertebral motion is detected when joint motion is asymmetrical or restricted bilaterally (see Figure 93-2). Causes of segmental vertebral motion restrictions include capsular fibrosis, effusion, and inflammation. Regional causes of vertebral movement restrictions may include periarticular soft tissue adhesions, musculotendonous contractures, or, more commonly, protective muscle spasms. Combining the evaluation of joint range of motion and the presence or absence of pain at the extremes of joint motion, diagnostic interpretations can be implied.27 Normal joint motion is painless, suggesting that articular structures are intact and functional. Normal joint mobility that has a painful end range of movement suggests that a minor sprain of the associated articular tissues is present. Painless joint hypomobility suggests that a contracture or adhesion is present. Painful hypomobility suggests the presence of an acute strain with secondary muscle guarding. Painless hypermobility of an articulation may indicate a complete rupture, whereas painful hypermobility suggests a partial tear of the evaluated structure. Motion palpation is used to evaluate each vertebral segment for loss of normal joint motion and overall resistance to induced motion (see Figure 93-4; Figure 93-5). Vertebral segments with altered motion palpation findings can occur with or without localized muscle hypertonicity and pain. Using palpation to evaluate the musculoskeletal system requires an understanding of how joint motion is assessed.9 Moving an articulation from a neutral position first involves evaluating joint motion that has minimal and uniform resistance. As the articulation is moved toward the end range of motion, a gradual increase in the resistance to movement occurs (i.e., elastic barrier) (see Figure 93-1). End range of motion starts when any change in resistance to passive joint movement is palpable. The elastic barrier is evaluated by bringing the articulation to tension and

Fig. 93-5  •  Demonstration of motion palpation with induced left lateral flexion of the thoracolumbar vertebral column.

applying gentle, rhythmic oscillations to qualify the resistance to movement. The normal joint end feel is initially soft and resilient and gradually becomes more restrictive as maximal joint range of motion is reached. This elastic barrier marks the end of physiological joint movement. A pathological or restrictive end range of motion is palpable earlier in passive joint movement and has an abrupt, restrictive end feel compared with normal joint end feel. The goal of palpating joint movement is to evaluate the initiation of motion resistance, the quality of joint motion and end feel, and the overall joint range of motion. Joint movement beyond its normal anatomical limits is characterized by ligamentous or articular capsule disruption and joint subluxation. Individual vertebral segments are evaluated for altered motion palpation findings in flexion and extension (Figures 93-6 and 93-7); right and left lateral flexion (see Figures 93-4 and 93-5); and right and left rotation. In a relaxed horse the articulations of the individual second to sixth cervical vertebrae are assessed for the presence or loss of the normal elastic barrier during combined lateral flexion and rotation. The articulation between the fourth and fifth cervical vertebrae seems to be commonly affected in most performance horses, presumably because of locally altered biomechanical influences. The individual spinous processes of the third to twelfth thoracic vertebrae are deviated manually from midline, while monitoring for signs of reduced vertebral motion, localized pain, and induced muscle hypertonicity. Horses with poorly fitting saddles (e.g., tree too narrow) resent motion palpation of the affected vertebrae. The remaining thoracolumbar region is assessed in lateral bending and flexion and extension for similar signs of joint dysfunction. While the clinician stands next to the

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PART IX  Therapeutics A

B

C Fig. 93-6  •  Diagram of segmental vertebral motion during manually induced extension of the vertebral column. Arrows indicate direction of applied forces to vertebral column. A, Normal segmental motion of the vertebral column. B, Locally restricted vertebral motion involving two vertebrae. C, Regionally restricted vertebral motion involving several vertebrae.

Fig. 93-7  •  Demonstration of motion palpation with induced extension of the thoracolumbar vertebral column.

for signs of reduced joint motion, localized pain, and induced muscle hypertonicity. Palpation of the entire musculoskeletal system, including joint motion assessment of the axial and appendicular skeleton, can be accomplished within 15 to 20 minutes. A neurological examination is indicated to evaluate horses with back problems to rule out traumatic, infectious, and toxic causes (see Chapter 11). Postural reactions also help to assess the proprioceptive status, which may be compromised in horses with certain vertebral column disorders. Rectal palpation is a commonly forgotten diagnostic test in horses with back problems. Osseous palpation rectally is useful for evaluating fractures, pelvic canal symmetry, and lumbosacral or sacroiliac joint osteoarthritis (OA). Externally induced pelvic motion during rectal palpation helps to assess lumbosacral joint motion internally. Palpation of the iliopsoas muscles for pain, swelling, or asymmetry is also important in evaluating horses with back pain. An orthopedic examination commonly is indicated to rule out or identify concurrent limb problems. Hematological evaluation, diagnostic analgesia, muscle biopsies, or cerebral spinal fluid analysis may be required in certain horses before chiropractic assessment and treatment. Imaging modalities that may contribute to a definitive diagnosis in horses with neck or back problems include radiography, myelography, ultrasonography, scintigraphy, computed tomography, and thermography. A thorough diagnostic workup and a definitive diagnosis, when available, are important for tailoring the appropriate chiropractic treatment and rehabilitation program. Horses with developmental osseous abnormalities, cervical vertebral fractures, thoracolumbar impinged dorsal spinous processes, equine protozoal myelitis, and sacroiliac joint luxation have been referred to me for chiropractic consultation. It was critical that these horses be properly diagnosed and that inappropriate chiropractic treatment not be applied, especially as the sole or primary therapeutic modality.

INDICATIONS FOR CHIROPRACTIC CARE horse, segmental vertebral motion in lateral bending is assessed with one hand lying over the intervertebral articulation to be evaluated. The other hand is placed at the tail head and is used to induce rhythmic oscillations to the caudal vertebral column. Normal lateral bending is maximal at the midthoracic vertebral region and gradually diminishes toward the lumbosacral junction. Conversely, flexion and extension are minimal in the thoracic region and gradually increase until the lumbosacral junction, the site of maximal flexion and extension. Segmental vertebral motion in flexion and extension requires the clinician to be on an elevated surface to induce ventrally directed rhythmic oscillations to the intervertebral articulations of the thirteenth to sixteenth thoracic vertebrae. The sacroiliac joints are evaluated for motion restriction or pain during induced joint motion, with an applied force directed ventrally over the tuber coxae, or during abaxial compression of the tubera sacrale (see Chapter 51). The caudal vertebrae are assessed by manipulation of individual vertebrae or by application of axial traction. The range of motion of the individual forelimb and hindlimb articulations also are evaluated in flexion and extension, internal and external rotation, abduction and adduction, and circumduction

Chiropractic provides additional diagnostic and therapeutic approaches that are not currently available in veterinary medicine. The principal indications for equine chiropractic evaluation are acute or chronic neck or back pain, localized or regional joint stiffness, poor performance, and an altered gait that is not associated with overt lameness (see Box 93-1). Musculoskeletal conditions that are chronic or recurring, are not diagnosed readily, or do not respond to conventional veterinary care also may be indications for chiropractic consultation. A thorough diagnostic workup is required to identify soft tissue and osseous pathological conditions, neurological disorders, or other lameness conditions that may not be responsive to chiropractic care. Horses with a localized limb lameness or diagnosed neurological disease are better treated with conventional veterinary medicine. However, if a residual lameness continues or a secondary vertebral column disorder (e.g., stiffness or asymmetry) is identified, then concurrent chiropractic care is indicated. Horses that have concurrent hock pain (e.g., OA) and a stiff, painful thoracolumbar or lumbosacral vertebral region are best managed by using a multidisciplinary approach of concurrent medical treatment of the hock OA and chiropractic evaluation and treatment of

Chapter 93  Chiropractic Evaluation and Management of Musculoskeletal Disorders the back problem. Most horses respond favorably to concurrent management, and owners appreciate a complete and thorough medical evaluation and treatment. Similarly, horses with chronic forelimb lameness often have compensatory pain and stiffness in the withers region, which are readily addressed with chiropractic or physical therapy techniques. The primary clinical signs that equine chiropractors assess are areas of localized musculoskeletal pain, muscle hypertonicity, and restricted joint motion. This triad of clinical signs can be found in a variety of horses with distal limb disorders, but it is most evident in those with neck or back problems. In general, localized pain, reduced vertebral segment motion, and local muscle spasms in the vertebral column are indications of a primary spinal disorder. In contrast, regional or diffuse pain, generalized stiffness, and widespread muscle hypertonicity are indications of a chronic or secondary spinal disorder, and further diagnostics should be done to identify the primary cause of lameness or poor performance. Chiropractic care may provide symptomatic relief in horses with early vertebral OA if related to joint hypomobility and subsequent immobilization degeneration. Research suggests that spinal manipulation also may affect certain visceral disorders (e.g., cardiovascular, respiratory, and gastrointestinal) through somatovisceral reflexes in animals and people.2,3 However, consistent and predictable long-term changes in visceral disorders rarely occur with chiropractic treatment in people or horses. Specially trained veterinarians or chiropractors, with advanced training and experience in equine chiropractic techniques, should be able to evaluate vertebral column disorders and determine if the condition will respond to chiropractic care, if further diagnostic evaluation is required, or if the horse would be better managed with traditional veterinary care. Unfortunately, equine chiropractors often are asked to treat horses as a last resort, when all else has failed or the disease has progressed to an irreversible condition. Chiropractic care has helped some of these horses with chronic conditions when other types of conventional treatment have failed. However, chiropractic is usually much more effective in the early stages of clinical disease versus end-stage disease, where reparative processes have been exhausted. Chiropractic care and other holistic modalities often fail when used as a last resort.

CONTRAINDICATIONS Chiropractic is not a cure-all for every back problem and is not suggested for treatment of horses with fractures, infections, neoplasia, metabolic disorders, or nonmechanically related joint disorders. Horses with serious diseases requiring immediate medical or surgical care need to be treated by conventional veterinary medicine before any chiropractic treatment is initiated. However, chiropractic care may contribute to the rehabilitation of most horses postoperatively, or those with medical conditions, by helping to restore normal musculoskeletal function. Chiropractic care usually is contraindicated in horses with acute stages of soft tissue injury. However, as the soft tissue injury heals, chiropractic has the potential to help restore normal joint motion, thus limiting the risk for future reinjury.9 Acute episodes of pain associated with OA, impinged

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dorsal spinous processes, and severe articular changes, such as joint subluxation or luxation, are often contraindications to chiropractic care. All horses with neurological diseases should be evaluated fully to assess the potential risks or benefits of chiropractic treatment. Cervical myelo­ pathy occurs because of structural and functional disorders in the cervical vertebrae. Static compression caused by malformation and dynamic lesions caused by vertebral segment hypermobility are contraindications to cervical manipulation. However, adjacent hypomobile vertebrae may require chiropractic treatment to help restore joint motion and reduce biomechanical stresses in the affected vertebrae. Chiropractic care cannot reverse severe degenerative processes or overt pathological conditions.

CHIROPRACTIC TECHNIQUES Most of the current knowledge about equine chiropractic was borrowed from chiropractic techniques, theories, and research used in people and adapted to horses. Therapeutic trials of chiropractic manipulations often are used because knowledge is limited about the effects of equine chiropractic. Chiropractic addresses mechanically related disorders of the musculoskeletal and nervous systems and provides a conservative means of treatment and prevention for horses with back problems. Chiropractic treatment uses an applied, controlled force to a specific anatomical region or osseous structure to produce a desired therapeutic response. Chiropractic manipulations are applied to areas of vertebral segment dysfunction. The condition of the horse is monitored closely as the neuromusculoskeletal system responds to the applied treatment. The applied treatment influences joint, muscle, and nerve function via mechanical and biological mechanisms.2 The therapeutic dosage of the applied chiropractic manipulation is modified by the number of vertebrae treated, the amount of force applied, and the frequency of treatment. The goal of chiropractic care is to restore normal joint motion, stimulate neurological reflexes, and reduce pain and muscle hypertonicity. Comparisons of sensitivity to palpation, muscle tone, and joint motion are made before and after treatment to evaluate the response to chiropractic treatment. Clinicians and clients often ask, how can a 500-kg horse be treated with chiropractic techniques? The answer is one vertebral segment at a time. Recent equine chiropractic research has demonstrated that forces applied to instrumented vertebral segments do induce substantial vertebral motion, usually beyond the normal range of segmental motion that occurs during locomotion.16 Segmental vertebral motion characteristics induced during chiropractic treatment in horses are similar to those reported in people.28 In a relaxed horse, the mass (i.e., vertebral segment) that is affected by the rapidly applied force is proportionately smaller than the mass of the clinician applying the treatment. However, if the horse does not relax the paraspinal musculature, then the mass that is affected increases dramatically from the mass of a few vertebral segments to the mass of the entire vertebral region, or potentially the entire horse. Effective joint mobilization or manipulation cannot be applied to a nervous, tense horse without risk of injury to the horse or the clinician. Chiropractic treatments in horses usually are done without any sedation or other medications, but they may occasionally be done with the

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PART IX  Therapeutics

horse under general anesthesia, or coupled with intraarti­ cular injections, if indicated.29 Typical indications for manipulation in people under anesthesia include chronic myositis or fibrosis, or acute musculoskeletal pain, where reflex muscle spasms prevent a thorough assessment or impede manipulative treatment. Untrained professionals who do not have a thorough understanding of joint physiology, vertebral anatomy, or chiropractic principles resort to overly aggressive and forceful means of applying an external force (e.g., mallets and 2 × 4s). Small, rapidly applied manual forces are easier to control and have a lower risk of soft tissue or bone injury than more forceful types of manipulation. A good rule of thumb is that if the procedure does not look like something that the practitioner would be willing to have done to himself or herself, then the procedure should not be done to a horse. Horses are usually held by a trained handler on a loose lead during chiropractic treatment. The cervical vertebrae, sacrum, and extremities are evaluated and manipulated as needed from ground level. However, the thoracolumbar vertebrae and pelvis often require an elevated surface on which to stand for effective manipulation and proper positioning of the clinician (see Figure 93-7). Equine chiropractic is physically demanding and requires substantial mental concentration. The clinician and the horse must be relaxed and focused on each other. Environmental distractions are counterproductive to effective chiropractic care. Muscle relaxation allows evaluation of the elastic barrier of the joint. Motion palpation is used to evaluate joint motion restrictions so that the manipulative thrust can be applied correctly. Stabilization of adjacent joints or vertebral segments is required for proper joint manipulation. Typically, an immediate reduction in pain and an increase in segmental vertebral motion are noted. Most horses also have increased muscle relaxation, but other therapies (e.g., acupuncture or stretching) often are used with chiropractic treatment to completely resolve any remaining muscle hypertonicity. In general, horses with conditions with an acute onset respond rapidly, whereas those with chronic conditions usually require longer treatment or rehabilitation. Horses with acute pain or vertebral column trauma may require initial antiinflammatory medication, physiotherapy modalities (e.g., ice), or rest before chiropractic treatment. If stiffness, local muscle hypertonicity, or pain remain, then two or three chiropractic treatments may be indicated. Horses with chronic neck or back stiffness may require monthly evaluation and treatment for several months’ duration. Owners often request chiropractic evaluation at the beginning of the performance season or a few days after athletic competition or as a general assessment of the overall musculoskeletal system. Similarly, horses may benefit from chiropractic treatment several days before an event. Because of ethical considerations or possible masking of musculoskeletal dysfunction, it is not recommended that chiropractic treatment be performed immediately before or during any competition. Posttreatment recommendations for actively training horses usually include stall rest or pasture turnout for one day, which provides an opportunity for the musculoskeletal system to respond to the applied treatment without immediate reexposure to potential inciting factors of the vertebral segment dysfunction. The horse returns to normal work the next day, unless other musculoskeletal injuries

are present, for which appropriate care is recommended. If stiffness or soreness is noted after chiropractic treatment, then an additional day of rest is suggested.

COMPLICATIONS OR ADVERSE EFFECTS Potential adverse effects from properly applied chiropractic treatments include a transient stiffness or worsening of the condition after treatment (e.g., aggravated clinical signs, worsening of preexisting state, regional soreness, or lameness).3 Adverse reactions from properly applied vertebral manipulation are typically uncommon, but they may occur immediately after treatment or insidiously within 6 to 12 hours. The undesired effects usually last less than 1 to 2 days and resolve without concurrent medical intervention. If increased or acute musculoskeletal dysfunction or lameness is noted after chiropractic treatment, then a thorough reexamination and appropriate medical treatment or physiotherapy should be pursued. If the condition does not improve with conservative care, referral for more extensive diagnostic or therapeutic modalities is recommended. Potential harmful side effects from improperly applied manipulation from untrained individuals may include permanent articular damage or loss of function (e.g., torn ligaments, injured muscles, luxated joints, fractures, or possible paralysis if a severe underlying pathological condition is present).

ADJUNCT RECOMMENDATIONS AND PROGNOSIS Chiropractic care often is supplemented with massage, physiotherapy modalities, and stretching or strengthening exercises to help soft tissue rehabilitation and to help restore normal vertebral joint motion (see Chapter 94). These concurrent therapies also help to encourage owner participation in the healing process and provide close monitoring of the horse’s progress. Other recommendations may include changes in training schedules or activities, corrective shoeing, or tack changes. Horses with poorly fitting saddles often have localized pain and muscle hypertonicity in the caudal withers region. Saddle refitting, coupled with chiropractic treatment of the painful withers region, leads to rapid recovery and management of a common problem for many horse owners. In one instance a horse with a 6-month history of consistently resenting saddle placement and bucking the owner off was treated chiropractically and the next week won 11 ribbons at the local country fair. Many horses with repetitive-use disorders may benefit from cross-training activities. Clinicians report synergistic therapeutic effects with the combined use of chiropractic, acupuncture, and other holistic modalities in horses. In general, horses with conditions with an acute onset respond rapidly and have a good prognosis for return to function. Horses with chronic injuries may gain only short-term improvement of restricted motion, pain, or muscle hypertonicity. This corresponds to current research on joint immobilization and spinal learning.9 Horses with chronic conditions usually require a series of treatments to effect a more lasting improvement. Musculoskeletal health depends on movement and use. Scientific evidence suggests that long-term rest and inactivity are contraindicated for back problems in people.



Chapter 94  Electrophysical Agents in Physiotherapy

SUMMARY A thorough knowledge of equine vertebral anatomy, biomechanics, and pathology is required to understand the principles and theories behind chiropractic and to apply its techniques properly. Because of its potential misuse, spinal evaluation and manipulative therapies should be provided only by specially trained veterinary clinicians or licensed manual therapists. Anecdotal evidence and clinical experience suggest that chiropractic is an effective adjunct modality for the diagnosis and conservative treatment of select musculoskeletal-related disorders in horses. Recent

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research including randomized, controlled clinical trials supports the efficacy of equine chiropractic techniques for reducing pain, improving flexibility, reducing muscle tone, and improving symmetry of spinal kinematics. Additional studies are needed to monitor the long-term changes and improvements in performance. Chiropractic provides additional diagnostic and therapeutic means that may help equine clinicians to identify and treat select musculoskeletal disorders. Chiropractic provides specialized evaluation and treatment of joint dysfunction and conservative treatment of neuromusculoskeletal disorders that currently lack treatments in traditional veterinary medicine.