Joint mobilization for children with central nervous system disorders: indications and precautions.

SR Harris, Phd, IT, FAPTA, is Associate Professor, School of Rehabilitation Medicine, University of British Columbia, T325-2211, Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2B5. Address all correspondence to Dr Harris.

BD Lundgren, 13PT, PT, is Instructor, School of Rehabilitation Medicine, University of British Columbia, and is in private practice in Vancouver, British Columbia, Canada.

Since the early 1970s, there has been a steady increase in the use of joint mobilization techniques by physical therapists.(1) The primary indication for use has been mechanical joint dysfunction in which there is restriction of joint play (accessory motion) leading to pain or limitation of active physiological movement. joint mobilization has most often been used in the evaluation and treatment of patients who have musculoskeletal disabilities of the spine and extremities. More recently, Cochrane(3) has suggested mobilization as an appropriate form of treatment for some of the joint restrictions that occur in children with cerebral palsy. The goals of the introductory section of this article are to define joint mobilization as used traditionally for adults with musculoskeletal disabilities, to discuss various rationales for its effects, to describe contraindications and precautions, and to discuss the efficacy of this treatment approach as reported in the research literature. The latter part of the article will deal with the applicability of joint mobilization for children with central nervous system (CNS) disorders.

Definitions

Used in its broadest sense, joint mobilization is a general term referring to any active or passive attempt to move a joint. As used in this article, the term is defined more specifically as any passive movement technique utilizing repetitive or oscillatory joint-play movements. Mobilization techniques are often graded as illustrated in Figure 1:

Grade 1: a small-amplitude movement performed at the beginning of the range.

Grade 2: a large-amplitude movement performed early in the range.

Grade 3: a large-amplitude movement performed to the end of the range.

Grade 4: a small-amplitude movement

performed at the end of the range.(4)

When these grades are used, techniques are performed slowly and rhythmically, making it possible for the patient to use voluntary muscle contraction to prevent the therapist from administering the technique

Grade 5 (Fig. 1) refers to manipulation, which is defined as a small-amplitude, high-velocity thrust applied to a joint at the limit of the available range of motion (ROM) and done so quickly that the patient cannot prevent the movement from taking place. Manipulation represents a progression beyond mobilization by providing a quick stretch to the joint, often accompanied by a cracking sound.(4,8)

There has been no suggestion in the physical therapy literature that manipulation would be an appropriate form of treatment for children with CNS disorders; indeed, common practice recognizes manipulation to be contraindicated in cases of physical involvement of the CNS."(9)(P446)

The reader should be aware, however, of these distinctions when considering the topic of joint mobilization. The term manual therapy will be used to refer to both mobilization and manipulation procedures.

Mechanical Joint Dysfunction

Dysfunction is a nonspecific term used to describe a deviation from normal. In the case of joint dysfunction, there is either deviation from the normal expected movement or pain accompanying the movement.(10) There are many different causes of mechanical joint dysfunction. For example, peripheral joint dysfunction can be due to capsular fibrosis, ligamentous adhesions, joint effusion, subluxation, and intra-articular derangement.(2) Spinal dysfunction has been related to disk lesions with or without nerve root involvement, zygapophyseal joint adhesions and derangements, segmental hypermobility, and subluxations.(4,8-11)

Not all types of joint dysfunction are appropriate for treatment by manual therapy. Careful evaluation of the type of dysfunction involves detailed assessment procedures.(5) "The specific signs and symptoms of the patient enable the physical therapist to develop a diagnosis and determine suitability for treatment. Careful analysis of clinical features guides progression of treatment.

Manual therapy has been stated to be most effective when directed at "mechanical joint dysfunction in which there is restriction of accessory motion due to capsular or ligamentous tightness or adherence.(2) Assessment, therefore, includes testing of the accessory movements particular to that joint to determine the presence of pain or resistance, or both, to movement.(4,7) Resistance to movement is typically produced by either capsuloligamentous tightness stiffness) or muscle activity (spasm).(7) The resistance produced by stiffness is described as being consistent in strength and position in the range of movement, whereas that produced by muscle spasm varies in response to the speed and method of the examination movement.(7) Skill and experience are required to appreciate these signs and symptoms when assessing the small movements associated with the peripheral and vertebral joints. The ability to reliably "feel" joint-play movements has been questioned by some authors(12) and supported by others.(13,14)

A recent study by Jull and colleagues(13) confirmed the ability of a therapist to accurately diagnose cervical zygaphoseal joint syndromes using manual procedures, but additional studies are required in this area.

Rationale for the Effects of Mobilization

The mechanisms by which joint mobilization or manipulation "work" are not known, although many hypotheses have been proposed as our knowledge of articular and soft tissue neurology, biomechanics, and pathology has expanded. Although treatment rationales have been developed for the areas receiving the most research attention (ie, spinal mobilization and manipulation),15 the proposed rationales for these effects can be applied to peripheral joints as well. Some of the possible mechanisms for these effects are described in the following paragraphs.

Neurophysiological Mechanisms for the Reduction of Pain and Muscle Spasm

Articular neurology has provided much of the background to understanding the effect of passive movement in modulating pain. The type I, II, and III mechanoreceptors located in joint capsules and ligaments are stimulated by active and passive joint movement.(16) Type IV nociceptors are completely inactive in normal situations, but are stimulated by excessive mechanical stress or by chemical irritants.(16) The gate-control theory postulated by Melzack and Wall in 1965(17) proposed that an afferent barrage from the joint receptors could modulate nociceptive afferent input by inhibition occurring primarily at the spinal cord level but influenced to some extent by higher centers.(15)

Passive mobilization techniques may be a means of activating type I and II mechanoreceptors, thereby reducing pain and reflex muscle spasm.(10) The type III mechanoreceptors (found only in capsules and ligaments of peripheral joints) may be activated by strong stretch or thrust techniques and may have an inhibitory effect on surrounding muscle.(10,16)

The gate-control theory has been criticized by Zusman, who contends that, in pain of spinal origin, manual therapy techniques applied at the end of the range of joint movement (ie, grades 3-5) effectively increase pain-free movement by two sequential mechanisms:

The first of these is inhibition of muscle contraction by discharge produced in joint afferents with end of range passive joint movement. The second is a subsequent decrease in the overall level of peripheral afferent input.(15)(p94)

Zusman's contentions", have indirect support in the literature. Passive movement of a joint may inhibit reflex contraction of muscles both local and distant to the joint.", Studies on decerebrate cats confirm that the afferent activity produced by end-of-range passive movements at the knee and elbow joints ha.9 an inhibitory effect on reflex muscle contraction.(19,20) Such findings would lend support to the use of joint mobilization for children with spasticity.

End-of-range passive movements may reduce peripheral input to the CNS, thereby decreasing pain, in two ways. The first is via a temporary reduction in intra-articular pressure,(21,22) thought to be due to decreased tension on the joint capsule. This decrease in tension could be due either to fluid reduction within the joint space or to stretch of collagen fibrils.(23) Giovanelli-blacker and colleagues2 demonstrated a reduction in the intra-articular pressure in human apophyseal joints following passive oscillations performed at the end range of joint movement. The second way in which end-of-range passive movements may reduce peripheral input to the CNS is through adaptation of the encapsulated endings of joint nerves to the mechanical stimulus of prolonged stretch of the periarticular soft tissue.(15,25,26)

Rationale for Effects Based on Mechanical Considerations

Although there have been no controlled studies to show that mobilization effectively restores ROM to hypomobile joints, there is literature that suggests mobilization may induce beneficial mechanical effects.(27-29)

When joint ROM is limited by capsular or ligamentous tightness or adherence, we believe that passive mobilization can he used to lengthen shortened structures or to rupture the adhesions. Paris(10) proposes that in order to have this effect, the mobilization must be performed at the limit of the joint's available range of movement, taking the tissue into the area of plastic deformation on the stress-strain curve, or, when adhesions are present, to the point of failure, causing rupture. Techniques presumably would have to be performed at the end of the range of movement (grades 3-5) for this effect. Secondary effects of improved mobility include beneficial effects on joint cartilage and intervertebral disks and improved blood and lymphatic flow.(30)

Studies comparing injured tissues (skin, tendons, ligaments) treated by immobilization with tissues treated by passive motion have demonstrated significant increases in cellularity, cell products, strength, and mobility in those tissues receiving passive motion.(30) Furthermore, Salter(31) has shown that injured articular cartilage treated by continuous passive motion improved markedly in the rate and extent of healing. A possible mechanism for this increased healing may be the improved nutrition of cartilage produced by movement. In their study of the effect of passive knee motion on the repaired medial collateral ligaments of rabbits, Long and colleagues(32) demonstrated improved matrix organization, collagen concentration, strength, and linear stiffness of ligament scars that were moved rather than immobilized.

Although the literature supports the beneficial effects of mobilization on healing, there is a need for further research to answer questions regarding the specifics of its application (eg, optimal duration, force, and velocity of movement) in contributing to the healing process.

Rationale for Effects Based on Psychological Considerations

Psychological benefits of manual therapy that have been reported related to such factors as "the laying on of hands," reducing a pain-fear cycle, and the charisma of the clinician.(11,15) Wells" estimates the placebo effect to be in the neighborhood of 20% to 30%; this possibility must be considered in any critical analysis of joint mobilization efficacy and in the choice of therapeutic technique.

Contraindications and Precautions

In discussing peripheral joints, Hertling and Kessler(2) describe absolute contraindications to mobilization as bacterial infection, neoplasm, and recent fracture; relative contraindications are joint effusion or inflammation, arthroses, internal derangement, and general debilitation. Spinal mobilization, particularly spinal manipulation, has a potential for inducing serious damage to the central nervous system. Grieve lists the following absolute contraindications to mobilization of the spine(9(p 445):

1. Malignancy involving the vertebral column.

2. Cauda equina lesions producing disturbance of bladder or bowel function.

3. Signs and symptoms of spinal cord involvement; involvement of more than one spinal nerve root on one side or of two adjacent roots in one limb only.

4. Rheumatoid collagen necrosis of vertebral ligaments; the cervical spine is especially vulnerable.

5. Active inflammatory and infective arthritis.

6. Bone disease of the spine.

Conditions that require special care in treatment include the following: the presence of neurological signs, osteoporosis, spondylolisthesis, and the presence of dizziness that is aggravated by neck rotation or extension.9 Documented cases in which spinal manipulation has produced consequences such as paraplegia, quadriplegia, and brain-stem thrombosis illustrate the potential danger of applying forceful techniques and emphasize the need for the clinician to proceed with skill, judgment, and caution.(33)

Application of Technique

In an effort to minimize risk to the patient, several important principles must be followed. The initial application of technique must be gentle. Assessment of the patient's signs and symptoms must occur continuously throughout the subsequent treatment. Any changes in these signs and symptoms must he used to monitor and guide treatment progression (ie, the therapist must continually monitor the response of the patient and of the joint being treated). The presence of pain or muscle spasm affects the application of the technique. Caution has been advised to avoid "pushing through" spasm when it is protecting the joint being treated.(6-8) The ability of the therapist to recognize the presence of muscle spasm while performing a small-amplitude accessory movement is therefore an essential safety factor.

Treatment techniques are chosen based on the spin, roll, and slide motions particular to the arthrokinematics of the joint and on the direction of the movement restriction.(2) AS Vet, the joint-play ROM has not been objectively quantified at each joint, making the grading of technique subjective. The grade of movement chosen for treatment is based on the effect desired and the irritability (ie, ease by which pain is provoked) of the joint being treated. Grades 1 and 2 are used to treat pain., grades 3 to 5 are used to increase ROM.

Efficacy of Joint Mobilization

The efficacy of any treatment modality is usually established through experimental research designs, such as clinical trials or single-subject research designs. Reviews of the literature and quantitative analyses of spinal mobilization and manipulation have concluded that efficacy has vet to be established reliably under controlled conditions.(34-36) There has been some evidence to support a small, short-term effect on pain(34-36) and a decrease in treatment visits when spinal manipulation is used.(36) In their metaanalysis on the efficacy of spinal manipulation and mobilization, Ottenbacher and Di Fabio(35) concluded that the effects of manipulation and mobilization were greater when provided in conjunction with other forms of treatment and were also greater within 1 month following therapy as compared with several months after treatment. This meta-analysis also showed that studies without randomassignment procedures were more likely to show effects in favor of the treatments than were more well-controlled studies.

Although the literature examining the efficacy of peripheral joint mobilization is extremely limited, there is some evidence to support its efficaCV.(28,37) We believe that, as peripheral joint mobilization appears to be more widely used than spinal mobilization for children with cerebral palsy, there is clearly a need for additional research on the efficacy of peripheral mobilization for all types of patients.

In summary, although manual therapy is widely used and is thought to be an effective approach for treatment of pain and joint hypomobility, the scientific evidence to support its efficacy is extremely limited (and nonexistent in pediatrics). The following section will explore the feasibility of using a technique designed for adults with orthopedic disorders on children with cerebral palsy and other CNS disabilities.

Joint Mobilization for Children with Central Nervous System Disorders 

Even in the typically developing child, there is evidence to suggest that joint mobilization may be contraindicated. For the child with a CNS disorder, such as cerebral palsy, additional risk factors must be considered. To better understand both indications and precautions for use of mobilization in children, musculoskeletal development will be briefly described for both typically developing children and children with cerebral palsy.

Developmental Considerations

In the typically developing child, somatic muscle growth is stimulated by skeletal growth as a result of the increasing distance imposed on the muscle attachments as bone grows.311 Thus, skeletal muscles "increase in length in parallel with, and apparently in response to, bone growth."(39(p543) Such changes in muscle may develop if opposing muscles are paralyzed or weak, as in the case of the child with spastic cerebral palsy or in a child with spasticity (hypertonia) secondary to head injury. When the agonist muscle fails to grow normally, muscle contractures result.(40) Similarly, changes in muscle can have an effect on bones or joints (eg, muscle contractures will lead to a decrease in joint movement with possible subsequent conversion of part of the articular cartilage into fibrous tissue).(38)

Growth cartilage is present at three sites in the developing child: the epiphyseal plate, the joint surface, and the apophysis or tendon insertion (Fig. 2).41 Injuries to each of these sites as a result of the repetitive stresses characteristic of some sports activities have been described in the literature.(41-43) During growth spurts in the typically developing child

.. there can be a real increase in muscle-tendon tightness about the joints, loss of flexibility, and an enhanced environment for overuse injury.(41(p342))

The epiphyseal growth plate has been reported to be particularly vulnerable to linear and torsional shears.(43)

Although muscle and bone growth are delayed in the involved limbs of children with cerebral palsy,44 growth spurts presumably take place, because overall growth occurs. Research on normal and spastic mice, however, suggests that "spastic muscle grows more slowly than normal muscle in relation to bone growth."(45)

Clearly, the musculoskeletal development of children with congenital or acquired CNS injuries, particularly those that result in spasticity, is different than that of typically developing children. Alterations in bone and muscle growth occur as a result of the effects of prolonged spasticity. According to Bleck,(46) contracture of the joint capsule occurs secondary to the immobility that results from spasticity.

Joint Mobilization in Children with Spasticity

Whereas capsular tightness may be the primary finding that indicates treatment by joint mobilization in persons with musculoskeletal disabilities, it is not the sole concern for the child with spastic cerebral palsy. When the associated findings of muscle shortening, hyperactive stretch reflexes, skeletal deviations, and muscle weakness are considered, the use of mobilization to enhance or restore joint mobility is not as straightforward. Further, clinicians must ponder the potential impact of applying repetitive mechanical forces to children. The predisposition of immature growth plates to injury-particularly during growth spurts-suggests the need to be cautious when using joint mobilization on children.

Cochrane(3) has suggested that joint motion limitations in older children with long-standing hypomobility may be secondary to capsular tightening and adhesions. She proposed that joint mobilization, provided in conjunction with neurophysiological forms of therapeutic exercise, may be indicated for such children. Cochrane cautions, however, that ... capsular dysfunction may be difficult to differentiate from movement restriction caused by muscle tightness in the patient with spasticity.(3(p1108))

She recommends that therapists become competent in assessing joints of individuals with and without orthopedic problems before trying to assess children who have neurologic deficits. In light of the complex problems associated with spasticity, such as hyperactive stretch reflexes, muscle shortening, and muscle weakness, we are in full agreement with Cochrane's suggestion.

In an overview of orthopedic manual therapy published in 1979, Cookson and Kent4 described the treatment approaches of a number of the leading proponents of manual therapyCyriax, Kaltenborn, Maitland, and Mennell. Common to all of these approaches is the need for both "subjective" and "objective" evaluations before initiating treatment. The subjective evaluation is based redominantly on a pain model, with the examiner questioning the patient about the nature, location, and severity of the pain. The use of such a subjective evaluation for children with CNS disorders is problematic for two reasons. First, pain is not commonly an issue for children with cerebral palsy, except in some cases of hip subluxation or dislocation. It is doubtful that mobilization would be useful in such cases, because dislocation can be reduced only by surgery.(47) Second, many children with cerebral palsy are unable to communicate effectively because of speech impairments or mental retardation. Thus, a subjective evaluation is often not possible or may be unreliable. Failure to obtain a reliable subjective evaluation interferes with the therapist's ability to monitor response to treatment (ie, to determine whether treatment soreness has occurred).

In summary, the capsular restrictions that occur in joints of older children with spastic cerebral palsy may be indications for using joint mobilization procedures.3 Caution, however, should be exercised. The technique that is recommended for a chronically tight joint is a vigorous grade 4 procedure.(48) As Cochrane has cautioned, however, care must be taken not to impose a quick stretch of the muscles surrounding the joint for fear of temporarily increasing spasticity.(3)

The presence of immature growth plates is another reason for caution. If joint mobilization were to be used for younger children or children undergoing growth spurts, for example, only gentle oscillations should be used to avoid the production of pain or reactive muscle spasm during treatment.

Central Nervous System Disorders for Which Joint Mobilization is Contraindicated

Although a case can be made for cautious and conservative use of peripheral joint mobilization in older children with joint restriction secondary to spasticity, there are a number of neurodevelopmental disabilities for which joint mobilization and, particularly spinal manipulation, would be strongly contraindicated. Although physical therapists would likely not use joint mobilization in the presence of hypermobile joints, specific statements about the children for whom this treatment is contraindicated are warranted.

In the child with pure athetoid and ataxic forms of cerebral palsy, joints tend to be hypermobile.(49) Hypermobility of the spine in children with athetoid cerebral palsy may lead to cervical instability; researchers have noted that "rapid and repetitious neck movements seem to accelerate the progression of cervical instability in athetoid CP patients."(50)

Another common neurodevelopmental disability in which joints are hypermobile secondary to lax ligaments is Down syndrome. In a report of 265 individuals with Down syndrome, 23% of the subjects had patellar instability leading to subluxation or dislocation and 10% had hip subluxation or dislocation." Of even greater concern in Down syndrome is the presence of atlantoaxial instability, which has been reported in up to 15% of individuals with this disorder.(52)

Other, less common, neurodevelopmental disabilities, such as PraderWilli syndrome, may be characterized by generalized hypotonia and hypermobile joints.5.3 For these children as well, joint mobilization would be contraindicated. Many children with generalized development delay of unknown etiology also exhibit hypotonia and ligamentous laxity.

Future Research Directions in Joint Mobilization for Children with Central Nervous System Disorders

Cochrane(3) concluded that research on mobilization was warranted, both to document benefits and to determine precautions, for using joint mobilization for children with CNS deficits. In spite of that call for research more than 4 years ago, no published studies were located in the medical literature that addressed either precautions for or efficacy of joint mobilization in children.

Despite the lack of demonstrated efficacy for these procedures, short courses on joint mobilization in children continue to be offered throughout North America. A random perusal of continuing education courses advertised in Physical Therapy during the past 2 years revealed more than a dozen short courses on mobilization or manual therapy in the child with neurological involvement.

As Cochrane(3) has suggested, case studies should be conducted to document the outcomes of joint mobilization. Because children with spasticity and secondary joint hypomobility appear to be the candidates of choice for this procedure, case studies should be conducted by therapists who have been well trained in manual therapy, both in their entry-level education and in specific continuing education courses that strengthen baseline knowledge and skills.

Single-subject research designs, with replications across several subjects, would provide appropriate methodologies for assessing short-term and long-term effects of mobilization on ROM and minimization of contractures.(54,55) Randomized clinical trials, although difficult to conduct, could provide more generalizable answers about the efficacy of joint mobilization procedures. In addressing the effectiveness of this treatment modality, functional outcome measures should be used.(56) Clinical researchers will need to address the effect of mobilization not only on impairment but also on disability. For example, even if joint mobilization could be shown to increase isolated joint motions in the upper extremity, what effect would this have on the child's level of independence in eating or dressing?

In addition to examining the efficacy of these procedures, research is needed to evaluate the reliability of assessment techniques in differentiating the causes of movement restriction (ie, muscle tightness versus capsular restriction). In addition to studying children who have spastic cerebral palsy, mobilization for children who have chronic spasticity and joint restrictions resulting from traumatic brain injury should also be examined.

Conclusions

As has been true throughout the history of physical therapy, the fervor for adopting an innovative treatment technique, such as joint mobilization, has far exceeded the availability of scientific support for these procedures.

Although there is limited research support for the use of mobilization in adults who have musculoskeletal disorders, there have been no published studies examining its efficacy for use in children with CNS disorders. Until such research is conducted and the results are disseminated, pediatric physical therapists should be cautious in their use of joint mobilization.

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