Review of Manual Therapy Techniques in Equine Practice

CLINICAL TECHNIQUES Review of Manual Therapy Techniques in Equine Practice Kevin K. Haussler, DVM, DC, PhD

ABSTRACT

INTRODUCTION

From the Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO. Reprint requests: Kevin K. Haussler, DVM, DC, PhD, Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523. 0737-0806/$ - see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2009.10.018

Manual therapy involves the application of the hands to the body, with a therapeutic intent.1 Chiropractic, osteopathy, physical therapy, massage therapy, and touch therapies are all considered forms of manual therapy techniques that have been developed for treatment of musculoskeletal disorders in humans and transferred for use in horses. Each technique has unique origins and different proposed biomechanical or physiological effects; however, all forms of manual therapy are characterized by applying variable gradations of manual force and degrees of soft-tissue or articular displacement.2 The goal of all manual therapies is to influence reparative or healing processes within the neuromusculoskeletal system. Therapeutic effects may be generalized to the entire body by inducing relaxation or altering behavior, regional effects may include alterations in pain perception or neuromuscular control, or effects may be localized to specific tissues and cellular responses.1 The challenge is in selecting the most appropriate and effective form of manual therapy to produce the desired physiological effect within an individual patient, such as increasing joint range of motion, reducing pain, or promoting general body relaxation. Anecdotally, all forms of manual therapy have reported levels of effectiveness in humans and horses. However, most claims are not supported by high levels of evidence such as randomized, controlled trials or systematic reviews of the published data. The purpose of this review article is to provide a brief overview of the scientific literature on the mechanisms of action and effectiveness of the different forms of manual therapy techniques used routinely in humans and to assess how effective and safe these techniques may be in horses, with a specific focus on joint mobilization and manipulation techniques applied to the proximal limbs and axial skeleton. The physical act of touching someone can induce physiologic responses and is often considered therapeutic.3 In human beings, therapeutic touch is used by nurses for nurturing premature infants, for supportive care in cancer or terminally-ill patients, and for support of the bereaved.4 Some well-known touch therapies in human beings include Healing Touch, Therapeutic Touch, and Reiki techniques.5 These techniques are considered a form of energy-based therapy in which practitioners move their hands over the body but do not touch the patient, or use a gentle touch over certain areas of the body with the goal of facilitating physical, emotional, mental, and

Journal of Equine Veterinary Science  Vol 29, No 12 (2009)

849

The realm of manual therapy includes diverse techniques such as chiropractic, osteopathy, physical therapy, massage therapy, and touch therapies, which have been developed for use in human beings and the techniques transferred to horses. All forms of manual therapy have reported levels of effectiveness for treating musculoskeletal issues in human beings, but mostly only anecdotally evidence exists in horses. The purpose of this review is to explore the scientific literature for potential common mechanisms of action and evidence of efficacy and safety for different forms of manual therapies, with a specific focus on joint mobilization and manipulation techniques. A description of a detailed musculoskeletal and spinal examination using manual therapy techniques is also presented. In humans, there is an extensive published data base for most forms of manual therapies; however, the methodological quality of most studies is poor, which often prevents definitive conclusions and recommendations. In horses, there are too few controlled studies to support most anecdotal claims of effectiveness. However, there is limited evidence suggesting effectiveness of spinal manipulation in reducing pain and muscle hypertonicity and increasing joint range-of-motion. Further research is needed to assess the efficacy of specific manual therapy techniques or combined treatments for management of documented back problems and specific lameness conditions in horses. Additional studies are also needed to define specific treatment parameters required for optimal management of select disease processes, such as the amount of force applied, and the frequency and duration of treatment. Keywords: Manual therapy; Chiropractic; Osteopathy; Mobilization; Manipulation

850

spiritual health. People use touch therapies for relaxation, stress reduction, and symptom relief. Reviews of controlled studies in evaluating effectiveness of touch therapies in human beings show promising results for pain relief, but further rigorous studies are needed to define clinical applications and mechanisms of action.5,6 Interestingly, trials conducted by more experienced practitioners seemed to yield greater effects in pain reduction. In horses, touch therapies have been primarily developed and promoted by Linda Tellington-Jones in a collection of techniques named the Tellington Touch Equine Awareness Method (TTEAM) or Tellington TTouch.7 Anecdotally, therapeutic touch is considered to improve behavior, performance, and well-being of horses and enhance the relationship between horse and rider, but no controlled studies exist to support these claims. Similar touch therapy techniques have been used in foals at birth to assess the effects of touch or imprint-training on behavioral reactions during selected handling procedures.8 Conditioned foals were significantly less resistant to touching the front and hind limbs and picking up the hind feet at 3 months of age. More controlled studies are needed to determine the effectiveness of touch theories in managing behavioral or musculoskeletal issues in horses. Massage therapy is defined as the manipulation of the skin and underlying soft tissues either manually (e.g., rubbing, kneading, or tapping) or with an instrument or machine (e.g., mechanical vibration) for therapeutic purposes. Massage techniques include many well-known methods such as Swedish massage, sports massage, trigger point therapy, cross-fiber friction massage, myofascial release, lymphatic drainage, and acupressure. Clinically, massage and soft-tissue mobilization are believed to increase blood flow, promote relaxation, relax muscles, increase tissue extensibility, reduce pain, and speed return to normal function; however, few controlled studies exist to support these claims.9 There are many anecdotal reports of the beneficial effects of massage on athletic performance; however, strong evidence in the form of controlled studies does not exist which proves the effects of massage on preventing injuries, recovery from exercise, or enhancing performance.10 Review of randomized, controlled trials in human beings suggests that massage may be beneficial for patients with subacute and chronic non-specific lowback pain, especially when combined with exercises and education programs.11,12 Massage is also a popular adjunct to cancer palliation, and systematic reviews suggest that it can alleviate a wide range of symptoms like pain, nausea, anxiety, depression, anger, stress, and fatigue.13,14However, the methodological quality of most massage studies is poor, which prevents definitive conclusions and recommendations. In horses, massage therapy has been shown to be effective for reducing stress-related behavior and pain thresholds within the thoracolumbar spine.15,16

KK Haussler  Vol 29, No 12 (2009)

A noncontrolled, clinical trial using eight horses measured increased stride lengths at the walk and trot compared pre and post-massage, but changes were not significant because of a small sample size.17 Manual lymph drainage has been described for use in the management of lymphedema in horses; however, no controlled studies exist evaluating its effectiveness.18 In a clinical trial in dogs, massage was significantly more effective in increasing lymph flow than passive flexion and extension of the forelimb or electrical stimulation of the forelimb musculature.19 More high-quality, scientific-based evidence is needed to support the use of massage therapy in horses.20 Passive stretching consists of applying forces to a limb or body segment in order to lengthen muscles or connective tissues beyond their normal resting lengths, with the intent of increasing joint range of motion and flexibility.21 The amplitude of motion and length of time that an individual stretch is held are gradually increased over time according to patient tolerance and ability. Stretching exercises are thought to increase joint range of motion, enhance flexibility, improve coordination and motor control, increase blood flow to muscles, and help to prevent injuries. Systematic reviews of the human literature suggest that stretching may have beneficial effects on increasing joint range of motion, reducing pain, and preventing workrelated musculoskeletal disorders in different occupations.22,23 Randomized studies suggest that regular stretching increases joint range of motion (average of 8 degrees) for more than 1 day after cessation of stretching and that the effects of stretching are possibly greater in muscle groups with limited extensibility.24 Regular stretching has been shown to improve performance by increasing force, jump height, and speed.25 Other systematic reviews report that there is insufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational human athletes.26–28 Because of the relatively low methodological quality of most studies, further research is needed to determine the proper role of stretching in human sports. Stretching combined with strengthening provides the largest improvement in nonspecific chronic neck or low back pain in human beings.29,30 In horses, passive stretching exercises of the limbs and axial skeleton have anecdotal effects of increasing stride length and joint range of motion and improving overall comfort.31 In a noncontrolled study, passive thoracic limb stretching lowered wither height as a result of possible relaxation of the fibromuscular thoracic girdle.32 However, a randomized controlled trial in riding school horses evaluating the effect of two different 8-week passive stretching programs reported no significant changes in stride length at the trot, but reported actual decreases in joint range of motion within the shoulder, stifle, and hock articulations.33 The authors concluded that daily stretching may be too intensive in normal horses and may

KK Haussler  Vol 29, No 12 (2009)

actually cause negative biomechanical effects. Additional studies on the effects of different stretching techniques and frequency for specific disease processes using objective outcome measures need to be completed before any further claims of performance enhancement in horses can be made. Mobilization is defined as manually-induced movement of articulations or soft tissues for therapeutic purposes. Soft-tissue mobilization focuses on restoring movement to the skin, connective tissue, ligaments, tendons, and muscles with the aim of modulating pain, reducing inflammation, improving tissue repair, increasing extensibility, and improving function.9 Joint mobilization is characterized as nonimpulsive, repetitive joint movements induced within the passive range of joint motion with the purpose of restoring normal and symmetric joint range of motion, to stretch connective tissues, and to restore normal joint end-feel.34 Manipulation is a manual procedure that involves a directed impulse which moves a joint or vertebral segment beyond its physiological range of motion, but does not exceed the anatomical limit of the articulation.35 Therefore, the primary biomechanical difference between joint mobilization and manipulation is the presence of a high-speed thrust or impulse. Spinal manipulation involves the application of controlled impulses to articular structures within the axial skeleton with the intent of reducing pain and muscle hypertonicity and increasing joint range of motion.36 Manual techniques used by physical therapists consist primarily of soft tissue and joint mobilization to assess the quality and quantity of joint range of motion and as a primary means of treating musculoskeletal disorders. Physical therapists often focus on functional assessment and diagnosis of neurophysiological processes as they relate to neuromotor control and the sensorimotor system, such as proprioception.37 Subjective assessment of the ease of joint motion, joint stability, and joint end-feel provides insights into the biomechanical and neurologic features of an articulation. Goniometry is often used to objectively quantify and document the amount of flexion or extension present at an articulation. Manually-applied physical therapy techniques also provide an adjunct to therapeutic exercises and rehabilitation of neuromotor control, where manual forces are used to induce passive stretching, weightshifting, and activation of spinal reflexes, which help to increase flexibility, stimulate proprioception, and strengthen core musculature.38 Peripheral nerve and nerve root mobilization techniques and exercises are also used by physical therapists for postoperative rehabilitation of low back pain.39 Few formal studies exist to support the use of active joint or spinal mobilization techniques in horses.40 Most mobilization studies in horses involve a period of induced joint immobilization by a fixture or cast, followed by allowing the horse to spontaneously weight bear and locomote

851

on the affected limb, without evaluation of specific softtissue or joint mobilization techniques.41 The chiropractic and osteopathic professions have many overlapping philosophies, techniques, and potential mechanisms of action related to joint mobilization and manipulation. Manual osteopathic techniques use a combination of mobilization and manipulation methods to address impaired or altered function of the musculoskeletal system (i.e., somatic dysfunction). From an osteopathic perspective, somatic dysfunction relates to impaired or altered function of skeletal, articular, myofascial, and related vascular, lymphatic, and neural elements.42 Human osteopathic techniques also include highly controversial methods associated with mobilizing cranial bones and abdominal viscera, which have questionable application to horses.43,44 Chiropractic treatment is characterized primarily as the application of high-velocity, low-amplitude (HVLA) thrusts to induce therapeutic effects in articular structures, muscle function, and neurological reflexes.35 From a chiropractic perspective, the basic elements of joint or spinal dysfunction include altered articular neurophysiology, biochemical alterations, pathologic changes within the joint capsule, and articular degeneration. Clinical signs of somatic or spinal dysfunction in horses include asymmetric or restricted joint motion, pain, and muscle hypertonicity.36 Human research has demonstrated reductions in pain and muscle hypertonicity and increased joint range of motion after chiropractic treatment.45–47 Anecdotal evidence and clinical experience suggest that manipulation is an effective adjunctive modality for the conservative treatment of select musculoskeletal-related disorders in horses.48 Therapeutic trials of spinal manipulation are often used because there is currently limited formal research available about the effectiveness of osteopathic or chiropractic techniques in equine practice. Equine osteopathic evaluation and treatment procedures have been described in textbooks and case reports, but no formal hypothesis-driven research exists.44,49,50 The focus of recent equine chiropractic research has been on assessing the clinical effects of spinal manipulation on pain relief, improving flexibility, reducing muscle hypertonicity, and restoring spinal motion symmetry. Obvious criticism has been directed at the physical ability to even induce movement in the horse’s back. Pilot work has demonstrated that manually-applied forces associated with chiropractic techniques are able to produce substantial segmental spinal motion.51 Two randomized, controlled clinical trials using pressure algometry to assess mechanical nociceptive thresholds (MNTs) in the thoracolumbar region of horses have demonstrated that both manual and instrument- assisted spinal manipulation can reduce back pain (or increase MNTs).16,52 Additional studies have assessed the effects of equine chiropractic techniques on increasing passive spinal mobility (i.e., flexibility) and reducing

KK Haussler  Vol 29, No 12 (2009)

852

longissimus muscle tone.40,53 The effect of manipulation on asymmetrical spinal movement patterns in horses with documented back pain suggests that chiropractic treatment elicits slight but significant changes in thoracolumbar and pelvic kinematics, and that some of these changes are likely to be beneficial.54,55

A

Neutral joint position Physiologic zone

Paraphysiologic space

Elastic barrier Anatomical limit of joint

Pathologic zone

JOINT MECHANICS The use of palpation techniques to qualitatively and quantitatively assess joint motion requires an understanding of joint mechanics.56 Joint motion can be categorized into three zones of movement: physiologic, paraphysiologic, and pathologic (Fig. 1A). The physiological zone of movement consists of both active and passive joint motion within all possible directions of movement (e.g., flexion, extension, lateral bending, and axial rotation). Passive movement of an articulation from a neutral joint position first involves evaluating the range of joint motion that has minimal, uniform resistance. Then as the articulation is moved toward the end range of passive joint motion, there is a gradual increase in the resistance to movement which terminates at an elastic barrier (i.e., joint end feel). The end range of motion begins with any palpable change in resistance to passive joint mobilization. Joint end feel is often evaluated by bringing an individual articulation to tension and applying rhythmic oscillations to qualify the resistance to movement.57 Normal joint end feel is initially soft and resilient but gradually becomes more restrictive as the limits of joint range of motion are reached. A pathologic or restrictive end range of motion is palpable earlier in passive joint movement and has an abrupt, hard end feel when compared with normal joint end feel. Each articulation within the body has unique palpatory end feels for each of the directions of joint motion (e.g., flexion, extension, lateral bending, etc.). The goal of palpating passive joint movement is to evaluate each articulation of interest for quality of joint motion, the initiation of resistance to motion and type of end feel, and the amount of motion within each of the principle directions of movement. The paraphysiologic space is bordered by the elastic and anatomical limits of an individual joint. Joint motion into the paraphysiologic space occurs only with the application of high velocity forces associated with joint manipulation. The anatomical barrier of the joint marks the junction between the paraphysiologic and pathologic zones of movement. The pathologic zone is characterized by the application of excessive forces or joint motion which causes an articulation to move beyond its anatomical limits and results in mechanical disruption of intra- and periarticular structures and subsequent joint instability or luxation. Active range of motion is characterized by the amplitude of voluntary joint movements (e.g., flexion and extension) produced by active muscle contractions (Fig. 1B).

B

Neutral joint Limit of voluntary position joint movement Active range of motion Passive range of motion Elastic barrier Anatomical limit of joint

C

Mobilization and stretching exercises

Active movements and exercise

Manipulation

Figure 1. Graphic representations of joint mechanics as it relates to joint mobilization and manipulation. (A) Zones of joint motion. (B) Active and passive joint ranges of motion. (C) Sites of active joint movement, mobilization, and manipulation.

Vertebral range of motion in left and right lateral bending or axial rotation is typically distributed symmetrically about a neutral joint position; however, joint ranges of motion in flexion versus extension at certain vertebral levels or limb articulations may be quite asymmetrical.58,59 Passive joint range of motion can be assessed only with the application of external articular forces. The limit of passive joint motion occurs beyond the range of voluntary joint movements and is the site where joint mobilization and stretching exercises are applied (Fig. 1C). Joint mobilization and manipulation are two types of induced articular movements used in musculoskeletal rehabilitation to

KK Haussler  Vol 29, No 12 (2009)

restore joint mobility and reduce pain. Mobilization is characterized as repetitive joint movements induced within the normal physiological range of joint motion. Joint manipulation involves the application of force to bring an articulation to end range of motion (i.e., pre-tension), and then applying a thrust or impulse to move the joint of interest beyond the elastic barrier and into the paraphysiological zone with the intent of stimulating both mechanical and neurophysiologic mechanisms. Joint mobilization and manipulation are thought to produce different physiologic effects; however, the evidence in human beings is mixed. Manipulation has been shown to immediately reduce spontaneous myoelectrical activity, whereas mobilization has not.60 For neck pain in human beings, manipulation produces significant reductions in pain and disability as compared with mobilization.61 However, both joint mobilization and manipulation increase cervical range of motion to a similar degree.47 Other studies report that neither manipulation nor mobilization is beneficial or significantly different for mechanical neck disorders.62 For acute low back pain in human beings, there is moderate evidence that spinal manipulation provides more short-term pain relief than does mobilization.45 It has been theorized that spinal manipulation preferentially influences a sensory bed which, in terms of anatomical location and function, is different from the sensory bed influenced by spinal mobilization techniques.63 Manipulation may particularly stimulate receptors within deep intervertebral muscles, whereas mobilization techniques most likely affect more superficial axial muscles. Only one study has compared mobilization to manipulation in horses, and spinal manipulation induced a 15% increase in displacement and a 20% increase in applied force as compared with mobilization.40 At most vertebral sites studied, manipulation increased the amplitudes of dorsoventral displacement and applied force, indicating of increased spinal flexibility and tolerance to pressure in the thoracolumbar region of the equine vertebral column. Joint manipulation often induces a palpable release or movement of the restricted articular end feel. An audible ‘‘cracking’’ or ‘‘popping’’ sound may also be heard during joint mobilization or manipulation because the applied force overcomes the elastic barrier of resistance.64,65 Rapid articular separation produces a cavitation of the synovial fluid.66 In human beings, radiographic studies of synovial articulations after manipulation have shown a radiolucent cavity within the joint space (i.e., vacuum phenomenon) that lasts for 15–20 minutes. A second attempt to recavitate the joint with a high-velocity thrust will be unsuccessful and potentially painful until the intra-articular gas has been reabsorbed (i.e., refractory period). Joint mobilization has no refractory period because synovial fluid cavitation is not produced during most mobilization procedures. The presence of joint cavitation induced during

853

manipulation has mixed clinical significance. Some authors suggest that joint cavitation is highly important and is required for successful joint manipulation64 whereas other studies state that joint cavitation is absolutely unimportant.67 The published data suggest that any stimulus that activates high-threshold receptors within the periarticular tissues has the potential to initiate unique neurologic reflexes associated with joint manipulation.68,69 The mechanical sensation and audible produced by joint cavitation has been used by some individuals to support the misconception of articular malpositioning or the concept of a ‘‘bone out of place,’’ which is an outdated theory and not supported by current spinal research.70 Palpatory changes in osseous symmetry after manipulation are often associated with soft-tissue alterations and not actual reduction of an articular misalignment.56

MECHANISMS OF ACTION Manual therapy is considered to produce physiological effects within local tissues, on sensory and motor components of the nervous system, and at a psychological or behavioral level.1 It is likely that specific manual therapy techniques are inherently more effective than others in addressing each of these local, regional, or systemic components.71 The challenge is in choosing the most appropriate form of manual therapy or a combination of techniques that will be efficacious for an individual patient with specific musculoskeletal disabilities. If soft-tissue restriction and pain are identified as the primary components of a musculoskeletal injury, then massage, stretching and soft-tissue mobilization techniques are indicated for increasing tissue extensibility.72 However, if the musculoskeletal dysfunction is localized to articular structures, then stretching, joint mobilization, and manipulation are the most indicated manual therapy techniques for restoring joint range of motion and reducing pain.45 Local tissue effects produced by manual therapy techniques relate to direct mechanical stimulation of skin, fascia, muscles, tendons, ligaments, and joint capsules.73 Mechanical effects can also influence the vasculature, lymphatics, and synovial fluid.74 Direct mechanical loading of tissues can alter tissue healing, the physical properties of tissues (e.g., elongation), and local tissue fluid dynamics associated with extracellular or intravascular fluids. Normal tissue repair and remodeling relies on mechanical stimulation of cells and tissues to restore optimal structural and functional properties, such as tensile strength and flexibility. Nonspecific back pain is most likely related to a functional impairment and not a structural disorder; therefore, many back problems may be related to muscle or joint dysfunction, with secondary soft-tissue irritation and pain generation.56 Soft-tissue contractures and adhesions are unwanted effects associated with musculoskeletal

854

injuries and postsurgical immobilization.41 Stretching exercises or direct mechanical mobilization of the affected tissue can be used to elongate contracted or fibrotic connective tissues to improve soft-tissue extensibility and increase joint range of motion.72 Tissue viability is highly dependent on its vascular and lymphatic supply which is often compromised because of mechanical disruption or ischemia. Soft-tissue or joint mobilization may facilitate flow to and from the affected tissues, help to reduce pain and edema, and decrease joint effusion.74 Joint manipulation can improve restricted joint mobility and may reduce the harmful effects associated with joint immobilization and joint capsule contractures. Limb and joint mobilization can also have direct mechanical effects on nerve roots and the dura mater, which may have clinical application in the treatment of perineural adhesions and edema.75 Tissue manipulation has an additional effect of stimulating regional or systemic changes in neurologic signaling related to pain processing and motor control. Manual therapy can provide effective management of pain and neuromuscular deficits associated with musculoskeletal injuries, alterations in postural control, and locomotory issues related to antalgic or compensatory gait.1 In response to chronic pain or stiffness, new movement patterns are developed 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 may continue to persist, which predispose adjacent articulations or muscles to injury.56 Activation of proprioceptors, nociceptors, and components of the muscle spindles provides afferent stimuli that have direct and widespread influences on components of the peripheral and central nervous systems that directly regulate muscle tone and movement patterns.56 The various forms of manual therapy are thought to affect different aspects of joint function through diverse mechanical and neurologic mechanisms.2 Alterations in articular neurophysiology from mechanical or chemical injuries can affect both mechanoreceptor and nociceptor function through increased joint capsule tension and nerve ending hypersensitivity.76 Mechanoreceptor stimulation induces reflex paraspinal musculature hypertonicity and altered local and systemic neurologic reflexes. Nociceptor stimulation results in a lowered pain threshold, sustained afferent stimulation (i.e., facilitation), reflex paraspinal musculature hypertonicity, and abnormal neurologic reflexes. Touch and light massage preferentially stimulate superficial proprioceptors, whereas any technique that involves deep tissue massage, stretching, muscle contraction, or joint movement has the potential to stimulate deep proprioceptors.1 Massage, stretching, and joint mobilization are also considered to affect more superficial epaxial muscles, such as the longissimus muscle, and to have a multisegmental effect. In contrast, manipulation preferentially stimulates mechanoreceptors within deep

KK Haussler  Vol 29, No 12 (2009)

multifidi muscles and has a more segmental focus.63 Joint manipulation can affect mechanoreceptors (i.e., Golgi tendon organ and muscle spindles) to induce reflex inhibition of pain and muscle relaxation and to correct abnormal movement patterns.77 Because of somatovisceral innervation, mobilization and manipulation within the trunk have possible influences on the autonomic system and visceral functions; however, the clinical significance and repeatability of these effects are largely unknown.78 The effects of touch or massage on psychological issues such as behavior or emotion are often dismissed as an insignificant component of the overall healing process in patients.1 Promoting general body relaxation and reducing anxiety may be significant components of some treatment protocols.79 Behaviors related to pain, depression, or fear are associated with patterned somatic responses, which may be manifested as generalized changes in muscle tone, autonomic activity, or altered pain tolerance. Other psychological factors associated with manual therapies include placebo effects and patient satisfaction. However, the role of placebo effects in horses and their owners is currently unknown.

SPINAL EXAMINATION The principle goal of the manual therapy examination is to identify whether a musculoskeletal problem exists and to localize the injury to either soft tissue, articular, or neurologic structures. Orthopedic and neurologic evaluations are important adjunctive assessments used to identify common causes of limb lameness, spinal injuries, and neurological disorders that are more appropriately and effectively treated with traditional medical or surgical approaches. Manual therapy evaluation and treatment is not a substitute for a thorough lameness examination and diagnostic imaging. However, horses with conditions that are not readily diagnosed using traditional modalities or with concurrent lameness and spinal dysfunction may benefit from a thorough manual therapy evaluation. Some horses present with vague or overlapping signs of neurologic disease and musculoskeletal pain, which may be differentiated with a detailed axial skeleton evaluation. The spinal examination also helps to identify and differentiate signs of acute and chronic spinal dysfunction and to localize stiffness, pain, or muscle hypertonicity to a few vertebral segments or an entire vertebral region. Examination of the neuromusculoskeletal system begins with a thorough medical history, detailed discussion of the chief complaint, and observation of the patient from a distance for evaluation of conformation, posture, and signs of lameness. The horse’s general attitude and behavior are monitored for signs of pain or discomfort. Many owners will report a change in behavior (i.e., pinned ears, swishing tail) because a horse with back pain anticipates being

KK Haussler  Vol 29, No 12 (2009)

touched or having the saddle placed on its back. Vertebral column conformation 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 believed to have a higher incidence of osseous disorders, whereas a long-backed horse is more prone to soft-tissue injuries.80 The horse is made to stand squarely on a hard, level surface and posture is evaluated for a preferred or shifting stance, head and neck carriage, vertebral curvatures, and muscular development and symmetry. Evaluation of spinal mobility during gait analysis focuses on observing the overall balance and fluidity of movement from head to tail, in addition to assessing thoracic and pelvic limb stride length, foot placement, and signs of lameness. Gait analysis and lameness examination are typically used to identify and localize limb lameness and to rule out signs of vertebral dysfunction, although limb lameness has been reported in 74% of horses with back problems.81 Neck or back motion asymmetries, restricted vertebral or pelvic mobility, not tracking straight, or lack of propulsion are a few spinal function characteristics that are evaluated. Tape on the tubera coxae or vertebral column midline may assist in visualization of subtle motion asymmetries. Normal vertebral column motion during the walk consists of small cumulative amounts of segmental motion, which produce an overall smooth curve or movement of the vertebral column. Evaluation of the response to placing a saddle on the horse, tightening of the girth, and riding exercise is important for a complete assessment of horses with potential back problems. Inspection of the tack for proper fit and use are always suggested on the initial examination of a horse with back pain or complaints of poor performance. Saddles and restraint devices should be evaluated for proper fit, positioning, and padding.82 A thorough physical examination, coupled with orthopedic and neurologic evaluation, is used to identify common causes of lameness or neurological disorders. A detailed spinal examination helps to identify compensatory or concurrent musculoskeletal issues not readily diagnosed or treated with traditional medical or surgical approaches. The spinal evaluation focuses on evaluating and localizing segmental vertebral dysfunction, which is characterized by localized pain, muscle hypertonicity, and reduced joint motion. The challenge, as with any musculoskeletal injury, is to identify the specific musculoskeletal structures that are affected and to quantify the associated disability or altered function present. Palpation is used to localize and identify soft tissue and osseous structures for changes in texture, tissue mobility, or resistance to pressure.80,83 The horse’s response to being approached and its anticipation of palpation is often used as a behavioral indication of potential back pain or hypersensitivity. Soft-tissue layers are evaluated from superficial to deep by increasing digital pressure

855

and by focusing attention to specific tissues or structures with discrete palpatory movements. Shapes of structures, transitions between structures, and attachment sites are also palpated.56 Soft-tissue texture and mobility can be compared between the skin, subcutaneous tissue, thoracolumbar fascia, and muscle; similar to layers of an onion (Fig. 2). Assessing patient response to palpation is especially important in evaluating tenderness or hypersensitivity. The epidermis should be evaluated for scabs, scrapes, lacerations, fly bites (ventral dermatitis), sarcoids, and dermatophilosis (rain scald), which can be primary causes of back pain or sources of irritation with saddle or girth placement. The dermis is palpated over the trunk region for the presence of eosinophilic granulomas or other dermal masses. The subcutaneous tissues are palpated for edema or cellulitis, masses, fat deposits, and for mobility of the cutis over the underlying loose connective tissues. The skin and subcutaneous tissues are gently mobilized by a firm, broad manual contact. Chronic scar tissue, adhesions, and fibrosis may produce pain or mechanical restrictions if affected tissues are restrained during locomotion or trunk movements. The superficial fascia is assessed for smoothness and uniform tonicity or compliance, and typically forms an external covering over muscles, whereas the deep fascia forms folds of connective tissue between muscle bellies and attaches to deeper osseous structures. The dense connective tissue that forms the deep fascia is systematically evaluated for masses, rents, scar tissue, and tonicity. Severe or deep trauma to the myofascial tissues (e.g., kicks, deep lacerations, abscesses, or hematomas) can produce residual fibrosis that limits adjacent muscular movements and fascial extensibility. The thoracolumbar fascia is the most prominent fascia of the trunk and is particularly evident at the thoracolumbar junction as it blends medially with the supraspinous ligament. In the lumbar region, the caudal aponeurotic portion of the thoracolumbar fascia attaches to the cranial aspect of the tuber sacrale and iliac wing, deep to the overlying middle gluteal muscle. The tendon of the thoracolumbar fascia is palpable cranial and medial to the tubera sacralia as it inserts on the second sacral spinous process in conjunction with the dorsal sacroiliac ligament.84 Other connective tissue structures, such as tendons and ligaments, are systematically evaluated for signs of acute or chronic injury. The spinal ligaments are systematically palpated for pain, swelling, thickening, fibrosis, and fiber disruption. Firm digital pressure is applied dorsally and laterally to the nuchal and supraspinous ligaments as they attach to the dorsal apices of the thoracolumbar spinous processes (Fig. 3). Fascial insertions from the thoracolumbar fascia are also palpated as they attach laterally to the supraspinous ligament. However, most pelvic ligaments are inaccessible to palpation because of their location deep to the gluteal musculature. The dorsal portion of the dorsal sacroiliac

856

KK Haussler  Vol 29, No 12 (2009)

Figure 2. Image of the cross-sectional spinal anatomy at the level of the fourth lumbar vertebra. Anatomical features and thickness of the skin, subcutaneous tissue, thoracolumbar fascia, and spinal musculature are illustrated. The epaxial spinal musculature (e.g., longissimus and multifidi muscles) lies dorsal to the transverse processes, and the psoas major and minor muscles are located ventrally.

ligament and the caudal portion of the sacrotuberous ligament are the only palpable ligaments within the pelvic region. The dorsal sacroiliac ligaments are palpable in the croup region as two large round ligaments that originate from the caudal aspect of the tuber sacrale and converge caudally to insert on the dorsal aspect of the sacral spinous processes. Firm digital pressure is applied dorsally and laterally to the dorsal sacroiliac ligaments, both individually and bilaterally to localized pain or swelling, indicative of desmitis. Specific mobilization forces applied to the pelvic prominences (i.e., tuber sacrale, tuber coxae, or ischial tuberosity) or the sacral apex can provide an indirect method of assessing the structural and functional status of the bony pelvis and the supporting sacroiliac ligaments.85 The evaluation of muscle begins with observation and palpation of the neck, trunk, and proximal limb musculature for development and symmetry. Muscle atrophy can be due to partial or complete denervation, disuse, malnutrition, metabolic, or immune-mediated disorders.86 Obese or out-of-condition horses often have accumulations of adipose tissue, poor muscle development, and indistinct myofascial borders, which make myofascial palpation difficult. Epaxial muscle development within the neck, trunk, and pelvis is assessed by laying a hand transversely across the spinal or gluteal musculature (Fig. 4). Horses with exceptional spinal muscle development have a palpable uniform convexity or outward curvature of the muscles along the entire length of the vertebra column from the poll to the scapula, along the trunk, and

Figure 3. Palpation of the supraspinous ligament and midline attachment of the thoracolumbar fascia. Firm digital pressure is applied laterally along individual spinous processes in an effort to localize and grade the severity of pain responses within the connective tissue structures.

over the croup and down the caudal aspect of the thigh. Deconditioning or poor flexibility may contribute to epaxial muscles with the thoracolumbar that are palpably flat between the dorsal spinous processes medially and the ribs laterally. Horses with chronic back pain or poor fitting saddles will have a palpable concavity or inward curvature of the epaxial muscles at the withers or along the trunk. Asymmetries in epaxial muscle development may be palpable cranial-to-caudal, medial-to-lateral, or left-to-right within the axial skeleton. The epaxial and pelvic musculature is further evaluated from superficial to deep, with detailed palpation to identify areas of abnormal muscle tonicity, pain, or fasciculations. Muscle palpation is made with light but firm pressure applied by a broad contact with the entire hand and not only the finger tips, which may unduly localize the applied pressure and precipitate a false positive pain response. Muscles are evaluated for masses, fibrosis, swellings, or depressions, and affected sites or muscles are identified. Regional muscle tone of the neck,

KK Haussler  Vol 29, No 12 (2009)

857

Figure 4. Palpation of muscle development and tone within the thoracic portion of the spinalis muscle located over the lateral withers. The presence and severity of left-right muscle asymmetries, muscle hypertonicity, and pain responses are documented.

trunk, and proximal limb musculature is assessed and compared left-to-right. Detailed palpation and a thorough knowledge of muscular anatomy will help to identify which muscle or group of muscles are primarily affected, and which distant muscles are likely to have secondary guarding because of common biomechanical or neurological inciting factors. Muscle tone is categorized as hypotonic, normal, or hypertonic. General muscle tone varies between horses and breeds. Nervous or excited horses will have overall increased muscle tone, whereas stoic, depressed, or systemically-ill horses will have reduced or sometimes flaccid muscle tone. Arabians tend to carry more muscle tone, whereas most warmbloods or draft breeds will allow deep palpation of their generally relaxed muscles. Muscle tone is an indirect measure of muscle activity or contraction. Diagnostic and kinesiologic electromyography provides a more direct assessment of muscle activity; however, it is not readily available in most clinical situations and it is often difficult to perform and interpret.86 Muscle hypotonicity or flaccidity is indicative of neuropathies, such as disuse or denervation atrophy. Muscle hypertonicity is the most commonly palpable abnormality in horses with acute or chronic back problems, and can have either neural or myopathic origins.86 Muscle hypertonicity may affect a small portion of a muscle (i.e., trigger point), an entire muscle belly, or a regional group of muscles. In general, localized muscle hypertonicity is considered indicative of an acute or primary back problem, whereas regional or generalized longissimus muscle hypertonicity is often associated with chronic pelvic limb lameness or systemic disease.86 Muscle

Figure 5. Palpation of the width of the retromandibular space between the caudal ramus of the mandible and the lateral wing of the atlas. Left-right asymmetry is indicative of possible atlanto-occipital joint dysfunction or structural vertebral abnormalities.

fasciculations are usually indicative of profound muscle weakness, electrolyte imbalance, or primary muscle pathology. However, muscles may also fasciculate at characteristic locations distant to an area of palpation, which is indicative of referred pain in human beings. Referred pain is difficult to truly assess in horses because of the lack of verbal feedback.87 Muscle spasms are characterized as an acute, severe form of muscle hypertonicity, with substantial pain, spasticity, and loss of muscle function. Osseous palpation involves evaluating bony structures for pain, morphology, asymmetries, and alignment. Horses with pain localized to the temporomandibular joints and hypertonicity of the adjacent muscles of mastication should be evaluated for potential dental malocclusion or oral pain. Osseous asymmetry in the space between the caudal ramus of the mandible and the lateral wing of the atlas can be identified in horses with upper cervical congenital malformations or occipitoatlantal trauma caused by pulling back in cross ties or flipping over backwards (Fig. 5). Individual cervical transverse processes, articular processes, and thoracolumbar and sacral spinous processes are palpated for a painful response to firm digital pressure (Fig. 6).88 Typical signs of discomfort include avoidance reactions such as rapid elevation of the head, extension of the back or withers

858

away from the applied pressure, or localized secondary muscle spasms, indicative of local injury or impinged spinous processes. Pressure algometry of osseous landmarks provides an objective measure of MNTs and allows monitoring of the efficacy of treatment protocols.89 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. Palpable deviations of individual spinous processes are common, but are typically not associated with spinous process fracture or vertebral malposition (i.e., bone out of place), as is commonly believed.90 Paired bony pelvis prominences are palpated for dorsoventral and craniocaudal asymmetries and pain response to manual compression. Small amplitudes of unilateral or bilateral prominence of the tuber sacrale are common and not considered clinically significant unless associated with clinical signs of localized pain, inflammation, or positive findings on diagnostic imaging (e.g., scintigraphy). The apex of the second sacral spinous process is a reliable landmark used to evaluate relative dorsal or ventral tuber sacrale displacement. Fractures of tuber coxae typically produce palpable bony asymmetries and ventral displacement of fracture fragments, which are readily diagnosed on oblique radiographs of the pelvis.91 The tail and caudal vertebrae are evaluated for tone, fractures, and osseous deviations. A complete musculoskeletal examination includes assessment of active and passive joint ranges of motion for all axial and appendicular articulations of interest. Active joint range of motion of the axial skeleton is evaluated during normal daily activities (e.g., lying, standing movements, or locomotion) or during induced vertebral movements while using a carrot or other treat to produce active movements of the head, neck, or trunk (Fig. 7). Similar procedures can be used therapeutically as active stretching exercises to increase neck or trunk range of motion or for developing coordination and strength of the muscles responsible for trunk stabilization.38 Normal vertebral movements consist of varying amounts and combinations of flexion, extension, left and right lateral bending, and left and right axial rotation. Active joint motion within most equine limb articulations consists almost exclusively of flexion-extension, with occasional joints capable of undergoing small amounts of internal or external rotation. Abnormal active joint motion is characterized by weakness, incoordination, asymmetry, restricted, or excessive joint movements. The willingness, coordination, and amount of vertebral or limb segment motion is compared bilaterally, and left-to-right range of motion asymmetries are documented. Local or regional causes of active vertebral movement restrictions or altered movement may include peripheral or central neuropathies, myopathies, intra-articular pathology (i.e., osteoarthritis), periarticular soft-tissue adhesions, musculotendinous contractures, or protective

KK Haussler  Vol 29, No 12 (2009)

Figure 6. Palpation of dorsal spinous processes within the thoracolumbar region. Firm digital pressure is applied dorsally along individual spinous processes in an effort to localize and grade the severity of the osseous pain responses.

muscle spasms. Joint hypermobility is usually indicative of articular instability that often requires immediate medical or surgical evaluation and stabilization and is generally a contraindication for most forms of manual therapy. Passive joint range of motion is evaluated by measuring the amount and characteristics of joint motion beyond the active range of joint motion (Fig. 1B). Assessing passive range of motion requires patient cooperation and muscular relaxation because each articulation is moved passively throughout its unique ranges and directions of motion. The goal of palpating joint movement is to evaluate the quality of joint motion, the initiation of resistance to motion and joint end feel, and the amplitude of joint motion present. Similar palpatory findings can be identified in soft tissues, such as skin, connective tissue, muscles, or ligaments.83 Passive joint range of motion is evaluated to detect whether a particular movement is normal, restricted, or hypermobile. Passive joint mobility can be assessed either segmentally through palpation of individual vertebral motion segments or limb articulations or evaluated regionally via passive mobilization of vertebral regions or entire

KK Haussler  Vol 29, No 12 (2009)

859

Figure 8. Evaluation of the quality and quantity of passive range-of-motion of the mandible during left and right lateral excursions. The presence and severity of joint motion asymmetry and pain responses are noted.

Figure 7. Evaluation of active cervical range of motion in left lateral bending. A carrot or similar treat is directed toward the elbow to assess quality and quantity of overall cervical range of motion. The treat can also be directed toward the ipsilateral stifle to assess lateral bending of the trunk, which is compared bilaterally.

limbs. Causes of restricted articular movement include soft tissue (e.g., capsular fibrosis, muscle spasms, or contractures) and osseous pathologies (e.g., malformations, osteoarthritis, or ankylosis). Restricted vertebral segment motion can occur with or without localized muscle hypertonicity or pain. Diagnostic interpretations of joint function can be implied by combining evaluation of joint range of motion and pain at the extremes of joint motion.92 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 a minor sprain of periarticular tissues or muscle. Painless joint hypomobility suggests a soft-tissue contracture or adhesion, whereas painful joint hypomobility an acute strain or intra-articular injury with secondary muscle guarding. Painless hypermobility of an articulation may indicate a complete rupture, whereas painful hypermobility suggests a partial tear of an intra- or periarticular structure. Evaluation of passive joint range of motion within the axial skeleton begins at the head and continues to the tip of the tail. In a relaxed horse, left-right lateral excursion of

the mandible is assessed for amplitude, quality, and symmetry (Fig. 8). Palpation of mandibular range of motion and audible contact of the cheek teeth are compared bilaterally. The dorsal and lateral excursion of the lingual process and basihyoid bone of the hyoid apparatus are assessed for restricted motion and pain, indicative of possible temporohyoid osteoarthropathy. The atlanto-occipital (Occ-C1) articulation is evaluated in full ranges of flexion, extension, and lateral bending for signs of pain or resisted motion (Fig. 9). The atlantoaxial (C1-C2) articulation is evaluated for altered or asymmetrical ranges of axial rotation. The intervertebral articulations of the second to seventh cervical vertebrae (C2-C7) are assessed individually for altered joint range of motion and joint end feel during combined lateral bending and rotation (Fig. 10). Articulations of the mid-cervical region (C4-C6) are commonly restricted and painful in performance horses, presumably because of locally altered biomechanical influences. The individual spinous processes of the third to twelfth thoracic vertebrae (T3-T12) are manually deviated from midline, while monitoring for signs of reduced vertebral motion, localized or generalized pain response, and induced muscle hypertonicity (Fig. 11). Horses with poorly fitting saddles (i.e., tree is too narrow) resent palpation and passive motion of the affected cranial thoracic vertebrae. The remaining thoracolumbar region (T13-L6) is evaluated in lateral bending and flexion and extension for similar signs of spinal dysfunction. Normal lateral bending range of motion is maximal at the mid-thoracic region and gradually diminishes toward the lumbosacral junction.59 Conversely, flexion and extension are minimal within the thoracic

860

Figure 9. Evaluation of the quality and quantity of passive lateral bending at the atlanto-occipital articulation. The presence and severity of left-right joint motion asymmetries and pain responses are documented. region and gradually increase toward the lumbosacral junction, which is the site of maximal flexion and extension range of motion within the trunk region. Evaluation of segmental vertebral motion in flexion and extension requires the clinician to be on an elevated surface to induce ventrally-directed rhythmic oscillations over the individual thoracolumbar intervertebral articulations (Fig. 12). Horses with impinged dorsal spinous processes strongly resent any induced extension of the affected vertebral segments. The pelvis and sacroiliac joints are evaluated for motion restrictions and pain during induced joint motion with ventrally-directed forces applied over the tuber coxae (Fig. 13) or during abaxial compression of the tubera sacralia (Fig. 14). The caudal vertebrae are assessed by passive range of motion of each intervertebral articulation and by applying axial traction to the tail. The passive range of motion of all thoracic and pelvic limb articulations is also evaluated in flexion and extension, internal and external rotation, abduction and adduction, and circumduction for signs of restricted joint motion, pain, inflammation, and muscle hypertonicity. Comparisons of the quality and quantity of passive range of motion are evaluated pre- and post-stretching exercises or joint manipulation to assess potential therapeutic responses within limb articulations or vertebral motion segments.93

KK Haussler  Vol 29, No 12 (2009)

Figure 10. Evaluation of the quality and quantity of passive lateral bending and axial rotation at the C5-C6 articulation. The presence and severity of left-right joint motion asymmetries, muscle hypertonic and pain responses are documented for each individual intervertebral articulation within the cervical spine.

INDICATIONS FOR JOINT MOBILIZATION AND MANIPULATION Back pain is a common cause of poor performance in equine athletes. Unfortunately, medical and surgical treatment options are often limited for affected horses. Manual therapy has the potential to provide important diagnostic and therapeutic approaches for addressing equine axial skeleton problems that are not currently available in veterinary medicine. Most of the current knowledge about equine manual therapies has been borrowed from human techniques, theories, and research and is applied to horses. Therapeutic trials of joint mobilization or manipulation are often used because of limited knowledge about the effects of manual therapy in horses. The indications for joint mobilization and manipulation are similar and include restricted joint range of motion, muscle spasms, pain, fibrosis, or contracted soft tissues.34 The principal indications for spinal manipulation are neck or back pain, localized or regional joint stiffness, poor performance, and altered gait that is not associated with overt lameness. A thorough diagnostic workup is required to identify soft tissue and osseous pathology, neurologic disorders, or other lameness conditions that may not be responsive to manual therapy. Clinical signs indicative of a primary spinal disorder include localized musculoskeletal pain, muscle

KK Haussler  Vol 29, No 12 (2009)

861

Figure 11. Evaluation of the quality and quantity of passive lateral bending and axial rotation of individual thoracic spinous process that form the withers. The presence and severity of left-right joint motion asymmetries, muscle hypertonicity, and pain responses are documented for each spinous process. Figure 13. Evaluation of the quality and quantity of passive lumbosacral, coxofemoral and pelvic motion induced during a ventrally-applied force over the tuber coxae. The presence and severity of restricted motion, muscle hypertonicity, and pain responses are documented.

Figure 12. Evaluation of the quality and quantity of passive thoracolumbar extension at each individual intervertebral articulation. The presence and severity of restricted motion, muscle hypertonicity, and local or generalized pain responses are documented.

hypertonicity, and restricted joint motion. This triad of clinical signs can also be found in a variety of lower limb disorders; however, they are most evident in horses with neck or back problems. Clinical signs indicative of chronic or secondary spinal disorders include regional or diffuse pain, generalized stiffness, and widespread muscle hypertonicity. In these cases, further diagnostic evaluation or imaging should be done to identify the primary cause of

lameness or poor performance. Manual therapy may help in the management of muscular, articular, and neurologic components of select musculoskeletal injuries in performance horses. Musculoskeletal conditions that are chronic or recurring, not readily diagnosed, or are not responding to conventional veterinary care may be indicators that manual therapy evaluation and treatment is needed. Manual therapy is usually more effective in the early clinical stages of disease processes versus end-stage disease where reparative processes have been exhausted. Joint manipulation is usually contraindicated in the acute stages of soft-tissue injury; however, mobilization is safer than manipulation and has been shown to have short-term benefits for acute neck or back pain in human beings.94 Manipulation is probably more effective than mobilization for chronic neck or back pain and has the potential to help restore normal joint motion, thus limiting the risk of reinjury.56 Contraindications for mobilization and manipulation are often based on clinical judgment and are related to the technique applied and skill or experience of the practitioner.34 Few absolute contraindications exist for joint mobilization if techniques are applied appropriately. Manual therapy is not a ‘‘cure all’’ for all joint or back problems and is generally contraindicated in the presence of

862

Figure 14. Evaluation of a pain response to abaxial compression of the tubera sacralia. A normal response consists of mild extension of the lumbosacral joint and contraction or mild fasciculations of the longissimus and middle gluteal muscles. A positive pain response occurs when horses unlock their stifles and exhibit dramatic dropping of the pelvis.

fractures, acute inflammatory or infectious joint disease, osteomyelitis, joint ankylosis, bleeding disorders, progressive neurological signs, and primary or metastatic tumors.34 Joint mobilization and manipulation cannot reverse severe degenerative processes or overt pathology. Acute episodes of osteoarthritis, impinged dorsal spinous processes, and severe articular instability, such as joint subluxation or luxation, are often contraindications for manipulation. Inadequate physical or spinal examination and poorly developed manipulative skills are also contraindications for applying manual therapy.95 All horses with neurologic diseases should be evaluated fully to assess the potential risks or benefits of joint mobilization or manipulation. Cervical vertebral myelopathy occurs because of both structural and functional disorders.96 Static compression caused by vertebral malformation and dynamic lesions caused by vertebral segment hypermobility are contraindications for cervical manipulation; however, adjacent regions of hypomobile vertebrae may benefit from mobilization or manipulation to help restore joint motion and reduce biomechanical stresses in the affected vertebral segments. Serious diseases requiring immediate medical or surgical care need to be ruled out and treated by conventional veterinary medicine before any routine manual therapy is initiated, although, manual techniques may

KK Haussler  Vol 29, No 12 (2009)

Figure 15. Application of a spring-loaded instrument (Activator, Activator Methods International Ltd., Phoenix, AZ) to bony or soft-tissue landmarks, with the aim of inducing high-velocity impulses during manually-assisted, mechanical-force procedures.

contribute to the rehabilitation of most postsurgical cases or severe musculoskeletal injuries by helping to restore normal joint motion and function. Horses that have concurrent hock pain (e.g., osteoarthritis) and a stiff, painful thoracolumbar or lumbosacral vertebral region are best managed by addressing all areas of musculoskeletal dysfunction. A multidisciplinary approach entails combined medical treatment of the hock osteoarthritis and manual therapy evaluation and treatment of the back problem. In human beings, adverse effects or risks of complications associated with joint mobilization are minimal. Mobilization is considered safer than manipulation.94 Some authors suggest that given the higher risk of adverse reactions and lack of demonstrated effectiveness of manipulation over mobilization, manual therapists should consider conservative mobilization, especially in human patients with severe neck pain.97 In human beings, most adverse events associated with spinal manipulation are benign and selflimiting.98 Potential mild adverse effects from properly applied manipulations include transient stiffness or worsening of the condition after treatment. Data from prospective studies suggest that minor, transient adverse events occur in approximately half of all patients during a course of spinal manipulative therapy.99,100 However, these mild adverse effects do not cause patients to stop seeking manipulative care. Mild adverse effects usually last less than 1–2 days and resolve without concurrent medical intervention.

KK Haussler  Vol 29, No 12 (2009)

Severe complications after spinal manipulation are typically uncommon and estimates of the incidence of range from 1 in 200,000 to 1 per 100 million manipulations in human beings.94,101,102 The most common serious adverse events in humans are vertebrobasilar accidents, disk herniation, and cauda equina syndrome.99 Although there is no evidence of increased risk of vertebrobasilar artery stroke associated with chiropractic care compared to primary medical care.103 Even though the complication rate of spinal manipulation is small, the potential for adverse outcomes must be considered because of the possibility of permanent impairment or death.94 The benefits of chiropractic care in human beings seem to outweigh the potential risks.104 The risk of adverse effects associated with joint mobilization or spinal manipulation is unknown in horses. The apparent safety of spinal manipulation, especially when compared with other medically accepted treatments for neck or low back pain in human beings, should stimulate its use in the conservative treatment of spinal-related problems.102,105 If an exacerbation of musculoskeletal dysfunction or lameness is noted after spinal manipulation, then a thorough re-examination and appropriate medical treatment should be pursued. If the condition does not improve with conservative care, referral for more extensive diagnostic evaluation or more aggressive medical treatment is recommended.

JOINT MOBILIZATION AND MANIPULATION TECHNIQUES Stretching exercises vary according to the direction, velocity, amplitude, and duration of the applied force or induced movement. However, it is difficult to identify which combination of positions, techniques, and durations of stretching are most effective to induce increased joint range of motion.106 Active stretching involves using the patient’s own movements to induce a stretch, whereas passive stretches are applied to relaxed muscles or connective tissues during passive soft tissue or joint mobilization. In horses, active stretches of the neck and trunk are often induced with baited (i.e., carrot) stretches with the aim to increase flexion, extension, or lateral bending of the axial skeleton (Fig. 7). It is very difficult to make horses do active stretching of the limbs; therefore, passive stretches are most commonly prescribed in horses.31 Stretching should be performed slowly to maximize tissue elongation because of creep and stress relaxation within fibrotic or shortened periarticular soft tissues.72 Sustained, low-load stretching is more effective than rapid, high-load stretching for altering viscoelastic properties within soft tissues.107 Rapid stretching may exceed the tissue’s mechanical properties and produce additional trauma within injured tissues.108 The force applied during stretching exercises should be tailored to specific phases of tissue repair.72 During the acute

863

inflammatory phase, stretching should be mostly avoided due to the increased risk of tissue injury. During the regenerative and remodeling phases of healing, tissues progressively regain tensile strength and applied manual forces can be gradually increased. The amount of force applied during passive stretching is largely based on the patient’s response and signs of pain. Musculoskeletal injuries are characterized by multiple tissue involvement, each of which has a different healing rate and unique mechanical response to stretching. Therefore, effective stretching programs are best tailored to address specific soft-tissue injuries and do not only focus on restoring joint motion. The duration of the applied stretch is dependent on the force applied, affected tissue shape and size, the amount of damage or fibrosis present, and the stage of tissue healing.72 In human beings, the recommended duration for stretching the musculotendinous unit varies from 6 to 60 seconds.108 Stretching for 30 seconds has been shown to be significantly more effective than 15-second stretches; however, structural and functional differences within each affected tissue makes general recommendations for stretching a particular articulation or limb difficult to establish.109 The mode of loading during an applied stretch varies from continuous to cyclic. Continuous or static loading during stretching exercises can be uncomfortable for some patients and is not recommended.72 Cyclic or rhythmic stretching is more comfortable and physiologic as it provides periods of tissue loading and unloading, which has biomechanical and neurological benefits. Cyclic loading also has cumulative effects on soft tissues as a result of incremental elongation and stress relaxation within each stretch cycle; however, these effects are maximized approximately within the first four cycles of loading.108 Therefore, recommendations for optimal passive stretching include applying four to five repetitions of slow, lowload forces held at the end range of motion of the affected tissues, with each stretch applied and released in 30-second cycles, without inducing pain. If performed inappropriately, stretches may cause or aggravate injuries.22 Therefore, thorough patient evaluation and proper stretching program design are required before implementing stretches. With minimal training, horses and their owners can be taught how to do simple but effective passive joint mobilization and active stretching exercises (i.e., carrot stretches) to improve both limb and axial skeleton flexibility. Selection factors for considering mobilization versus manipulation include the technical training and skill of the practitioner, perceived risks versus benefits, the presence of acute pain and inflammation, and pathoanatomic considerations.63 Joint mobilization is easier to apply, requires less psychomotor skills, has minimal risks, and can be used in the presence of acute pain and inflammation, as compared to manipulation. Manual therapy procedures are

864

also dependent on the ability of the patient to relax and the patent response to the applied force. Characteristics of joint mobilization and manipulation include factors related to specificity, leverage, velocity, amplitude, direction, and prestress of the applied force.2 Additional factors are related to joint position and frequency or oscillation of the applied forces.34 Levers are used to increase mechanical advantage and assist in applying force to an articulation or body segment to induce joint motion. Long levers include using the limbs or head and neck as levers to induce spinal motion, instead of inducing motion at one or two individual vertebrae by using transverse or spinous processes as short lever contacts. Velocity relates to the speed of the impulse applied to move a vertebra or body segment, and displacement is the distance over which the applied thrust is applied. Amplitude refers to the amount of force applied. With long-lever techniques, lower amplitudes of force are required to induce similar joint motion as short-lever contacts. However, the rationale for using short-lever techniques is to increase the specificity of the applied thrust because a single vertebral process is contacted on the vertebra of interest with short-lever techniques. With long levers, it is likely that multiple articulations are included between the doctor’s contact and the body segment of interest, which produces a more generalized treatment effect. Using a specific contact is theorized to address a single articulation; however, studies on treatment effects indicate that specific contact techniques produce local, as well as, regional and systemic effects.46 The therapeutic dosage of joint mobilization or manipulation is also determined by the number of vertebrae or body segments treated and the frequency of the applied treatments. Biomechanical characteristics of joint mobilization include low peak forces, slow application, low velocity movements, and large displacements. Mobilization of the thoracic spine produces 2-3 cm displacements, whereas manipulation induces 6-12 mm displacements.63 Mobilization is typically applied with long lever-arm, low velocity, oscillatory forces within or at the limits of physiological joint range of motion without imparting a thrust or impulse. Mobilization is also performed within the patient’s ability to resist the applied motion and therefore requires cooperation and relaxation of the patient. Mobilization is usually applied in a graded manner, with each grade increasing the range of joint movement. Grade 1 and 2 mobilizations are characterized by slow oscillations within the first 25% to 50% of the available joint motion, with the goal of reducing pain. Grade 3 and 4 mobilizations involve slow oscillations at or near the end of available joint motion, which are used to increase joint range of motion. Some mobilization techniques may include a hold and stretch at the end range of motion. Distraction or traction refers to applying manual or mechanical forces to induce separation of adjacent joint surfaces, which causes stretching of

KK Haussler  Vol 29, No 12 (2009)

the joint capsule, reduced intra-articular pressure, and is often used to reduce joint luxations. Manipulation is characterized by short lever-arm, high velocity, and low-amplitude forces applied outside of the physiological zone of joint motion. Therefore, it is often difficult for patients to resist or guard against the applied impulse. Chiropractic techniques are often characterized as HVLA thrusts delivered to a specified vertebral process (short-lever arm) in a specific direction.2 Osteopathic techniques also include similar HVLA thrusts applied to single or multiple articulations with the goal of increasing joint range of motion and reducing pain.44 Mobilization and manipulation forces can both be focused on a specific joint or anatomical region in a specific direction; however, mobilization is often considered a general technique and manipulation is theoretically considered more specific. The therapeutic dosage of applied mobilizations or manipulations is modified by the number of vertebrae or articulations treated, the amount of force applied, and the frequency and duration of treatment. However, there is a lack of good scientific evidence on which optimal dosage recommendations for continued care can be based; therefore, therapeutic trials are often used on an individual basis.110 The goal of manual therapy 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 and effectiveness of manual therapy. In human beings, the application of manual forces can be combined with a wide diversity of therapeutic or medical techniques to produce varying effects. Hand-held, spring-loaded or electromechanical devices can be used to apply single or multiple impulses to articulations or tissues in a series of techniques named manually-assisted, mechanical-force procedures (Fig. 15). It has been reported that approximately 40 N of force is required to activate mechanical and neurologic responses associated with spinal manipulation.111 Manually-applied impulses applied to the human cervical and lumbar spine range from 40–400 N and occur over 30–150 milliseconds. Similar amplitudes of force have been measured with instrument-assisted manipulations (i.e., 72 N–230 N); however, the impulse occurs over a much shorter time (i.e., 0.1–5.0 milliseconds). It is hypothesized that the velocity of the applied force may be more important than the amplitude of the applied force.111 Randomized studies have shown similar effectiveness using either manual or instrument-assisted treatment techniques.112,113 Using a stick and mallet or similar percussive device to apply sharp, mechanical forces to dorsal spinous processes has been reported in horses to reduce back pain and increase spinal range of motion, but controlled studies are lacking.54 Theoretically, there is an increased risk for injury using

KK Haussler  Vol 29, No 12 (2009)

instrument-assisted techniques or hammers to treat horses because of the possibility of applying excessive forces by inexperienced or lay practitioners, with little or no knowledge of spinal or joint biomechanics. Joint mobilization and manipulation can be combined with sedation or general anesthesia, which provides increased relaxation and analgesia for evaluation of subtle joint motion restrictions or treatment of joint contractures and spinal pain, without the influence of conscious pain or protective muscle guarding.114 Indications for manipulation under anesthesia in human beings include pain that will not allow conscious manipulation, conditions that do not respond to conscious spinal manipulation within 4 to 8 weeks, chronic joint or soft-tissue fibrosis, acute myofascial rigidity and painful inhibition, severe joint dysfunction, refractory contained disc herniation, and multiple recurrences of a condition.95 The risks of manipulation under sedation or general anesthesia include the inability of patients to provide verbal feedback on pain or to resist overzealous manipulation because intrinsic guarding mechanisms associated with voluntary muscle contraction are absent, which can produce an increased risk of iatrogenic injuries.95 Spinal manipulation under sedation and anesthesia has been used in horses to address reduced joint mobility; however, controlled studies are lacking.50,115,116 In a case series of 86 horses, 88% of horses maintained improved ranges of pain-free joint motion after cervical mobilization and sustained stretching at the end range of motion while under anesthesia.115 Similar indications and risks associated with the mobilization or manipulation under anesthesia in human beings are expected in horses. Although, no significant adverse effects have been reported with cervical mobilization under general anesthesia in horses.115 Well-designed, controlled studies are needed to further investigate the safety and effectiveness of these techniques in equine practice. Manipulation combined with epidural analgesia or epidural medications consists of segmental anesthesia with simultaneous epidural corticosteroid injection and spinal manipulation.114 Indications for this procedure in human beings include the following: epidural anesthesia is less costly and is associated with fewer risks than general anesthesia, patients are able to cooperate during treatment, and epidural corticosteroids reduce inflammation and reduce fibrosis and adhesions, as compared to manipulation under anesthesia alone. One possible indication for using this technique in horses is severe or compensatory spinal pain or stiffness associated with chronic limb lameness. Another reported technique involves joint mobilization or manipulation combined with intra-articular injection of either local anesthetic or corticosteroids, which helps to reduce pain and inflammation associated with osteoarthritis and to more effectively restore joint mobility.114 Indications in human beings include recalcitrant joint pain that

865

prevents mobilization or rehabilitation of the affected region. In horses, one possible indication includes cervical facet osteoarthritis, where acute pain and inflammation can be initially controlled with intra-articular facet injections; however, recurrent stiffness and disability are common. Intra-articular injections combined with a series of spinal manipulations, stretching, and strengthening exercises provide the opportunity to increase pain-free cervical mobility and reduce long-term morbidly or recurrence. Controlled clinical trails are needed to assess other possible clinical indications and effectiveness of manipulation combined with intra-articular injections in horses.

DIRECTION OF FUTURE STUDIES A thorough knowledge of equine anatomy, soft tissue and joint biomechanics, musculoskeletal pathology, and tissuehealing processes is required to understand the basic principles of the various forms of manual therapies and to properly apply the associated techniques. There is a severe deficiency in evidence for using touch, massage, stretching exercises, and joint mobilization in horses. Spinal manipulation has been shown in several studies to be effective for reducing pain, improving flexibility, reducing muscle tone, and improving symmetry of spinal kinematics in horses. Because of potential misuse and safety issues, mobilization and manipulative therapies should be provided only by specially-trained veterinarians or licensed human manual therapists. Further research is needed to assess the effectiveness of specific manual therapy recommendations or combined treatments for management of back problems and lameness issues. Additional studies are needed to objectively monitor both short- and long-term clinical effects and improvements in performance. Currently, there is no validated equine model for studying the effects of manual therapies that would allow characterization of the anatomic, biomechanical, neurophysiologic, pathophysiologic, cellular, or biochemical changes associated with soft tissue and joint mobilization or high-velocity thrusts. Further understanding of the local and systemic effects of mobilization and manipulation on pain reduction and tissue healing is also needed. Additional studies are needed to determine the duration of the clinical effects of manual therapies and to assess if and how these modalities can enhance athletic performance. There is a need of controlled trials using different forms of spinal manipulation (e.g., manual thrusts versus instrument-assisted thrusts versus manipulation under anesthesia) need to be done to determine which method is most effective for treating specific disease processes. New methods of objectively measuring musculoskeletal dysfunction and further studies into the pathophysiology of chronic pain syndromes are needed to help assess the effectiveness of manual therapies on

KK Haussler  Vol 29, No 12 (2009)

866

reducing morbidity and improving overall performance in equine athletes.

20. Ramey DW, Tiidus PM. Massage therapy in horses: assessing its effectiveness from empirical data in humans and animals. Compendium 2002;24:418–423. 21. Blignault K. Stretch exercises for your horse. London: J.A. Allen;

REFERENCES

2003.

1. Lederman E. Fundamentals of manual therapy: physiology, neu-

22. da Costa BR, Vieira ER. Stretching to reduce work-related muscu-

rology and psychology. St. Louis, MO: Churchill Livingstone;

loskeletal disorders: a systematic review. J Rehabil Med 2008;40: 321–328.

1997. 2. Bergmann TF. High-velocity low-amplitude manipulative tech-

23. Radford JA, Burns J, Buchbinder R, Landorf KB, Cook C. Does

niques. In: Haldeman S, ed. Principles and practice of chiropractic,

stretching increase ankle dorsiflexion range of motion? A systematic

3rd ed. New York, NY: McGraw-Hill; 2005:755–766. 3. Coppa D. The internal process of therapeutic touch. J Holist Nurs

24. Harvey L, Herbert R, Crosbie J. Does stretching induce lasting in-

2008;26:17–24. 4. Monroe CM. The effects of therapeutic touch on pain. J Holist Nurs 2009;27:85–92. 5. So PS, Jiang Y, Qin Y. Touch therapies for pain relief in adults. Cochrane Database Syst Rev 2008;4. CD006535.

review. Br J Sports Med 2006;40:870–875 [discussion 875]. creases in joint ROM? A systematic review. Physiother Res Int 2002; 7:1–13. 25. Shrier I. Does stretching improve performance? A systematic and critical review of the literature. Clin J Sport Med 2004;14: 267–273.

6. Bardia A, Barton DL, Prokop LJ, Bauer BA, Moynihan TJ. Efficacy

26. Thacker SB, Gilchrist J, Stroup DF, Kimsey CD Jr. The impact of

of complementary and alternative medicine therapies in relieving cancer pain: a systematic review. J Clin Oncol 2006;24:

stretching on sports injury risk: a systematic review of the literature.

5457–5464.

Med Sci Sports Exerc 2004;36:371–378. 27. Herbert RD, Gabriel M. Effects of stretching before and after exer-

7. Tellington-Jones L, Lieberman B. The ultimate horse behavior and

cising on muscle soreness and risk of injury: systematic review. Br

training book. North Pomfret, VT: Trafalgar Square Books; 2006. 8. Spier SJ, Berger Pusterla J, Villarroel A, Pusterla N. Outcome of

Med J 2002;325:468. 28. Small K, Mc Naughton L, Matthews M. A systematic review into the

tactile conditioning of neonates, or ‘‘imprint training’’ on selected

efficacy of static stretching as part of a warm-up for the prevention of

handling measures in foals. Vet J 2004;168:252–258. 9. Bromiley MW. Massage techniques for horse and rider. Wiltshire, England: The Crowood Press Ltd; 2002. 10. Hemmings BJ. Physiological, psychological and performance effects of massage in sport: a review of the literature. Phys Ther Sport 2001; 2:165–170. 11. Furlan AD, Imamura M, Dryden T, Irwin E. Massage for low-back pain. Cochrane Database Syst Rev 2008. CD001929. 12. Ernst E. Massage therapy for low back pain: a systematic review. J Pain Symptom Manage 1999;17:65–69. 13. Ernst E. Massage therapy for cancer palliation and supportive care: a systematic review of randomised clinical trials. Support Care Cancer 2009;17:333–337. 14. Wilkinson S, Barnes K, Storey L. Massage for symptom relief in patients with cancer: systematic review. J Adv Nurs 2008;63:430–439.

exercise-related injury. Res Sports Med 2008;16:213–231. 29. Hayden JA, van Tulder MW, Tomlinson G. Systematic review: strategies for using exercise therapy to improve outcomes in chronic low back pain. Ann Intern Med 2005;142:776–785. 30. Kay TM, Gross A, Goldsmith C, Santaguida PL, Hoving J, Bronfort G. Exercises for mechanical neck disorders. Cochrane Database Syst Rev 2005;3. CD004250. 31. Frick A. Fitness in motion: keeping your equine’s zone at peak performance. Guilford, CT: The Lyons Press; 2007. 32. Giovagnoli G, Plebani G, Daubon JC. Withers height variations after muscle stretching. In: Proceedings of the Conference on Equine Sports Medicine and Science. Oslo, Norway: 2004:172–176. 33. Rose NS, Northrop AJ, Brigden CV, Martin JH. Effects of a stretching regime on stride length and range of motion in equine trot. Vet J 2009;181:53–55.

effect of massage to reduce stress in the horse. J Equine Vet Sci

34. Scaringe J, Kawaoka C. Mobilization techniques. In: Haldeman S, ed. Principles and practice of chiropractic, 3rd ed. New York, NY:

2004;24:76–82. 16. Sullivan KA, Hill AE, Haussler KK. The effects of chiropractic, mas-

35. Gatterman MI. What’s in a word. In: Gatterman MI, ed. Founda-

sage and phenylbutazone on spinal mechanical nociceptive thresh-

tions of chiropractic. St. Louis, MO: Mosby-Yearbook, Inc; 1995:

15. McBride SD, Hemmings A, Robinson K. A preliminary study on the

olds in horses without clinical signs. Equine Vet J 2008;40:14–20. 17. Wilson J. The effects of sports massage on athletic performance and general function. Massage Ther J 2002;90–100.

McGraw-Hill; 2005:767–785.

5–17. 36. Haussler KK. Chiropractic evaluation and management. Vet Clin North Am Equine Pract 1999;15:195–209.

18. Fedele C, von Rautenfeld DB. Manual lymph drainage for equine

37. McGowan CM, Stubbs NC, Jull GA. Equine physiotherapy: a com-

lymphoedema-treatment strategy and therapist training. Equine

parative view of the science underlying the profession. Equine Vet J

Vet Educ 2007;26–31. 19. Ladd MP, Kottke FJ, Blanchard RS. Studies of the effect of massage

38. Stubbs NC, Clayton HM. Activate your horse’s core: unmounted

on the flow of lymph from the foreleg of the dog. Arch Phys Med

exercises for dynamic mobility, strength and balance. Mason, MI:

Rehabil 1952;33:604–612.

Sport Horse Publications; 2008.

2007;39:90–94.

KK Haussler  Vol 29, No 12 (2009)

39. Ellis RF, Hing WA. Neural mobilization: a systematic review of randomized controlled trials with an analysis of therapeutic efficacy. J Man Manip Ther 2008;16:8–22.

867

56. Liebenson C. Rehabilitation of the spine, 1st ed. Baltimore, MD: Williams & Wilkins; 1996. 57. Haneline MT, Cooperstein R, Young M, Birkeland K. Spinal mo-

40. Haussler KK, Hill AE, Puttlitz CM, Mcllwraith CW. Effects of ver-

tion palpation: a comparison of studies that assessed intersegmental

tebral mobilization and manipulation on kinematics of the thoraco-

end feel vs excursion. J Manipulative Physiol Ther 2008;31:616–

lumbar region. Am J Vet Res 2007;68:508–516.

626.

41. van Harreveld PD, Lillich JD, Kawcak CE, Gaughan EM, Mclaughlin RM, Debowes RM. Clinical evaluation of the effects of

58. Clayton HM, Townsend HG. Kinematics of the cervical spine of the adult horse. Equine Vet J 1989;21:189–192.

immobilization followed by remobilization and exercise on the meta-

59. Townsend HG, Leach DH, Fretz PB. Kinematics of the equine

carpophalangeal joint in horses. Am J Vet Res 2002;63:282–288.

thoracolumbar spine. Equine Vet J 1983;15:117–122.

42. Parsons J, Marcer N. The osteopathic lesion or somatic dysfunction.

60. Leach RA. Segmental dysfunction hypothesis. In: Leach RA, ed.

In: Parsons J, Marcer N, eds. Osteopathy: models for diagnosis,

The chiropractic theories: principles and clinical applications, 3rd ed. Baltimore, MD: Williams & Wilkins; 1994:43–54.

treatment and practice. Philadelphia, PA: Churchill Livingstone; 2006:17–39.

61. Cleland JA, Glynn P, Whitman JM, Eberhart SL, MacDonald C,

43. Parsons J, Marcer N. Osteopathy: models for diagnosis, treatment and practice. Philadelphia, PA: Churchill Livingstone; 2006.

Childs JD. Short-term effects of thrust versus nonthrust mobilization/manipulation directed at the thoracic spine in patients with

44. Verschooten F. Osteopathy in locomotion problems of the horse:

neck pain: a randomized clinical trial. Phys Ther 2007;87:431–

a critical evaluation. Vlaams Diergeneeskd Tijdschr 1992;61: 116–120. 45. Bronfort G, Haas M, Evans RL, Bouter LM. Efficacy of spinal manipulation and mobilization for low back pain and neck pain: a sys-

440. 62. Gross AR, Hoving JL, Haines TA, Goldsmith CH, Kay T, Aker P, et al. A Cochrane review of manipulation and mobilization for mechanical neck disorders. Spine 2004;29:1541–1548.

tematic review and best evidence synthesis. Spine J 2004;4:

63. Bolton PS, Budgell BS. Spinal manipulation and spinal mobilization

335–356. 46. Nansel DD, Waldorf T, Cooperstein R. Effect of cervical spinal ad-

influence different axial sensory beds. Med Hypotheses 2006;66: 258–262.

justments on lumbar paraspinal muscle tone: evidence for facilita-

64. Brodeur R. The audible release associated with joint manipulation.

tion of intersegmental tonic neck reflexes. J Manipulative Physiol Ther 1993;16:91–95. 47. Cassidy JD, Lopes AA, Yong-Hing K. The immediate effect of manipulation versus mobilization on pain and range of motion in the

J Manipulative Physiol Ther 1995;18:155–164. 65. Reggars JW, Pollard HP. Analysis of zygapophyseal joint cracking during chiropractic manipulation. J Manipulative Physiol Ther 1995;18:65–71.

cervical spine: a randomized controlled trial. J Manipulative Physiol

66. Herzog W, Zhang YT, Conway PJ, Kawchuk GN. Cavitation

Ther 1992;15:570–575. 48. Herrod-Taylor EE. A technique for manipulation of the spine in

sounds during spinal manipulative treatments. J Manipulative Physiol Ther 1993;16:523–526.

horses. Vet Record 1967;81:437–439. 49. Evrard P. Introduction aux techniques oste´opathiques struturelles applique´es au cheval. Thy-Le-Chaˆteau: Olivier e´diteur 2002.

67. Flynn TW, Childs JD, Fritz JM. The audible pop from high-velocity

50. Pusey A, Colles C, Brooks J. Osteopathic treatment of horses––a ret-

68. Triano JJ. Studies on the biomechanical effect of a spinal adjust-

rospective study. Br Osteo J 1995;16:30–32.

thrust manipulation and outcome in individuals with low back pain. J Manipulative Physiol Ther 2006;29:40–45. ment. J Manipulative Physiol Ther 1992;15:71–75.

51. Haussler KK, Bertram JEA, Gellman K. In-vivo segmental kinemat-

69. Dishman JD, Burke J. Spinal reflex excitability changes after cervical

ics of the thoracolumbar spinal region in horses and effects of chiropractic manipulations. Proc Am Assoc Equine Prac 1999;45:

and lumbar spinal manipulation: a comparative study. Spine J 2003; 3:204–212.

327–329. 52. Haussler KK, Erb HN. Pressure algometry: objective assessment of back pain and effects of chiropractic treatment. Proc Am Assoc Equine Pract 2003;49:66–70. 53. Wakeling JM, Barnett K, Price S, Nankervis K. Effects of manipulative therapy on the longissimus dorsi in the equine back. Equine and Comp Exercise Physiol 2006;3:153–160. 54. Faber MJ, van Weeren PR, Schepers M, Barneveld A. Long-term follow-up of manipulative treatment in a horse with back problems.

70. Tullberg T, Blomberg S, Branth B, Johnsson R. Manipulation does not alter the position of the sacroiliac joint. Spine 1998;23: 1124–1129. 71. Triano J. The theoretical basis for spinal manipulation. In: Haldeman S, ed. Principles and practice of chiropractic, 3rd ed. New York, NY: McGraw-Hill; 2005:361–381. 72. Lederman E. The biomechanical response. In: Lederman E, ed. Fundamentals of manual therapy: physiology, neurology and psychology. St. Louis, MO: Churchill Livingstone; 1997:23–37.

J Vet Med A Physiol Pathol Clin Med 2003;50:241–245. 55. Go´mez Alvarez CB, L’Ami JJ, Moffat D, Back W, van Weeren PR.

73. Threlkeld AJ. The effects of manual therapy on connective tissue.

Effect of chiropractic manipulations on the kinematics of back and

74. Lederman E. Changes in tissue fluid dynamics. In: Lederman E, ed.

limbs in horses with clinically diagnosed back problems. Equine

Fundamentals of manual therapy: physiology, neurology and psy-

Vet J 2008;40:153–159.

chology. St. Louis, MO: Churchill Livingstone; 1997:39–54.

Phys Ther 1992;72:893–902.

KK Haussler  Vol 29, No 12 (2009)

868

75. Gruenenfelder FI, Boos A, Mouwen M, Steffen F. Evaluation of the

94. Hurwitz EL, Aker PD, Adams AH, Meeker WC, Shekelle PG.

anatomic effect of physical therapy exercises for mobilization of lum-

Manipulation and mobilization of the cervical spine. A systematic

bar spinal nerves and the dura mater in dogs. Am J Vet Res 2006;67:

review of the literature. Spine 1996;21:1746–1759 [discussion

1773–1779. 76. Cameron MH. Physical agents in rehabilitation. Philadelphia, PA: W.B. Saunders; 1999.

1759-1760]. 95. West DT, Mathews RS, Miller MR, Kent GM. Effective management of spinal pain in one hundred seventy-seven patients evaluated

77. Pickar JG. Neurophysiological effects of spinal manipulation. Spine J 2002;2:357–371.

for manipulation under anesthesia. J Manipulative Physiol Ther 1999;22:299–308.

78. Schmid A, Brunner F, Wright A, Bachmann LM. Paradigm shift in

96. Levine JM, Adam E, MacKay RJ, Walker MA, Frederick JD,

manual therapy? Evidence for a central nervous system component

Cohen ND. Confirmed and presumptive cervical vertebral compres-

in the response to passive cervical joint mobilisation. Man Ther

sive myelopathy in older horses: a retrospective study (1992-2004).

2008;13:387–396. 79. Moyer CA, Rounds J, Hannum JW. A meta-analysis of massage therapy research. Psychol Bull 2004;130:3–18.

J Vet Intern Med 2007;21:812–819. 97. Hurwitz EL, Morgenstern H, Vassilaki M, Chiang LM. Frequency and clinical predictors of adverse reactions to chiropractic care in the

80. Cauvin E. Assessment of back pain in horses. In Pract 1997;19: 522–533.

UCLA neck pain study. Spine 2005;30:1477–1484. 98. Rubinstein SM. Adverse events following chiropractic care for sub-

81. Landman MA, de Blaauw JA, van Weeren PR, Hofland LJ. Field

jects with neck or low-back pain: do the benefits outweigh the risks?

study of the prevalence of lameness in horses with back problems. Vet Rec 2004;155:165–168. 82. Harman J. Recognizing saddle problems. In: Harman J, ed. The

J Manipulative Physiol Ther 2008;31:461–464. 99. Stevinson C, Ernst E. Risks associated with spinal manipulation. Am J Med 2002;112:566–571.

horse’s pain-free back and saddle-fit book: ensure soundness and

100. Senstad O, Leboeuf-Yde C, Borchgrevink C. Frequency and charac-

comfort with back analysts and correct use of saddles and pads.

teristics of side effects of spinal manipulative therapy. Spine 1997;

North Pomfret, VT: Trafalgar Square Publishing; 2004:15–22. 83. Chaitow L. Palpation skills. New York, NY: Churchill Livingston;

22:435–440 [discussion 440-441]. 101. Thiel HW, Bolton JE, Docherty S, Portlock JC. Safety of chiroprac-

1997. 84. Engeli E, Yeager AE, Erb HN, Haussler KK. Ultrasonographic technique and normal anatomic features of the sacroiliac region in horses. Vet Radiol Ultrasound 2006;47:391–403. 85. Haussler KK. Diagnosis and management of sacroiliac joint injuries. In: Ross MW, Dyson S, eds. Diagnosis and management of lameness in the horse. Philadelphia, PA: W.B. Saunders; 2003:501–508. 86. Valberg SJ, Hodgson DR. Diseases of muscle. In: Smith BP, ed. Large animal internal medicine, 3rd ed. St. Louis, MO: Mosby; 2002:1266–1291. 87. Martin BB Jr, Klide AM. Physical examination of horses with back pain. Vet Clin North Am Equine Pract 1999;15:61–70. vi. 88. Haussler KK. Chiropractic evaluation and management of musculoskeletal disorders. In: Ross MW, Dyson S, eds. Diagnosis and management of lameness in the horse. Philadelphia, PA: W.B. Saunders; 2003:803–811. 89. Haussler KK, Erb HN. Mechanical nociceptive thresholds in the axial skeleton of horses. Equine Vet J 2006;38:70–75. 90. Haussler KK, Stover SM, Willits NH. Pathologic changes in the lumbosacral vertebrae and pelvis in thoroughbred racehorses. Am J Vet Res 1999;60:143–153.

tic manipulation of the cervical spine: a prospective national survey. Spine 2007;32:2375–2378 [discussion 2379]. 102. Oliphant D. Safety of spinal manipulation in the treatment of lumbar disk herniations: a systematic review and risk assessment. J Manipulative Physiol Ther 2004;27:197–210. 103. Cassidy JD, Boyle E, Coˆte´ P, He Y, Hogg-Johnson S, Silver FL, et al. Risk of vertebrobasilar stroke and chiropractic care: results of a population-based case-control and case-crossover study. Spine 2008;33:S176–S183. 104. Rubinstein SM, Leboeuf-Yde C, Knol DL, de Koekkoek TE, Pfeifle CE, van Tulder MW. The benefits outweigh the risks for patients undergoing chiropractic care for neck pain: a prospective, multicenter, cohort study. J Manipulative Physiol Ther 2007;30: 408–418. 105. Dabbs V, Lauretti WJ. A risk assessment of cervical manipulation vs. NSAIDs for the treatment of neck pain. J Manipulative Physiol Ther 1995;18:530–536. 106. Decoster LC, Cleland J, Altieri C, Russell P. The effects of hamstring stretching on range of motion: a systematic literature review. J Orthop Sports Phys Ther 2005;35:377–387. 107. Light KE, Nuzik S, Personius W, Barstrom A. Low-load prolonged

91. Dabareiner RM, Cole RC. Fractures of the tuber coxa of the ilium in

stretch vs. high-load brief stretch in treating knee contractures. Phys

horses: 29 cases (1996-2007). J Am Vet Med Assoc 2009;234: 1303–1307.

Ther 1984;64:330–333. 108. Taylor DC, Dalton JD Jr, Seaber AV, Garrett WG Jr. Viscoelastic

92. Kessler RM, Hertling D. Assessment of musculoskeletal disorders.

properties of muscle-tendon units. The biomechanical effects of

In: Hertling D, Kessler RM, eds. Management of common musculoskeletal disorders: physical therapy principles and methods, 2nd ed.

109. Bandy WD, Irion JM. The effect of time on static stretch on the flex-

Philadelphia, PA: J.B. Lippincott; 1990:68–71. 93. Haussler KK. Equine chiropractic: general principles and clinical applications. Proc Am Assoc Equine Pract 2000;46:84–93.

stretching. Am J Sports Med 1990;18:300–309. ibility of the hamstring muscles. Phys Ther 1994;74:845–850. 110. Bronfort G, Haas M, Evans R. The clinical effectiveness of spinal manipulation for musculoskeletal conditions. In: Haldeman S, ed.

KK Haussler  Vol 29, No 12 (2009)

Principles and practice of chiropractic, 3rd ed. New York, NY: McGraw-Hill; 2005:147–166. 111. Fuhr AW, Menke JM. Status of activator methods chiropractic technique, theory, and practice. J Manipulative Physiol Ther 2005;28: e1–e20.

869

(HVLA) manipulation in the treatment of cervical spine dysfunction. J Manipulative Physiol Ther 2001;24:260–271. 114. Kohlbeck FJ, Haldeman S. Medication-assisted spinal manipulation. Spine J 2002;2:288–302. 115. Ahern TJ. Cervical vertebral mobilization under anesthetic

112. Shearar KA, Colloca CJ, White HL. A randomized clinical trial of man-

(CVMUA): a physical therapy for the treatment of cervico-spinal

ual versus mechanical force manipulation in the treatment of sacroiliac joint syndrome. J Manipulative Physiol Ther 2005;28:493–501.

pain and stiffness. J Equine Vet Sci 1994;14:540–545. 116. Brooks J, Colles C, Pusey A. The role of osteopathy in the treatment

113. Wood TG, Colloca CJ, Matthews R. A pilot randomized clinical

of the horse. In: Rossdale P, Green R, eds. Guardians of the horse II.

trial on the relative effect of instrumental (MFMA) versus manual

Newmarket. Suffolk: Romney Publications; 2001:40–49.