FUNDAMENTAL PRINCIPLES OF MOBILIZATION

A healthy joint is one that moves without limitation. In synovial joints, movement stimulates biological activity by moving synovial fluid to areas of avascular articular cartilage. Additionally, strength and resiliency of capsular tissue and periarticular tissue is maintained via joint movement. Immobilization causes a host of negative consequences such as fatty infiltration, articular adhesions, and physiologic changes to the strength and tolerance of ligaments, tendons, and capsular tissue. The term mobilization refers to an attempt to restore joint motion or mobility, or decrease pain associated with joint structures using manual, passive accessory-joint movement.4,21

Joint mobilizations are passive, skilled manual therapy techniques applied to joints and related soft tissues at varying speeds and amplitudes using physiologic or accessory motions for therapeutic purposes.¹ Range of motion (ROM) involves physiologic movements which are active/passive motions at a given joint through one of the traditional cardinal planes of flexion, extension, abduction, adduction, or internal and external rotation. Physiologic movements are sometimes called osteokinematic, classical, or traditional movements because they are movements of the actual bones of a given joint system. These motions can be visualized by the naked eye and are commonly measured by goniometric assessment. Osteokinematic motions occur in the cardinal planes of movement such as frontal, sagittal, and transverse. Hip, knee, and shoulder flexion movements are examples of osteokinematic movements. These are all movements that can occur under volitional control. Arthrokinematic movements are those that occur at the bone ends, without regard to the movement. These movements are not under volitional control. These types of movements are known as accessory movements involving motions specific to articulating joint surfaces.^4,21 These accessory joint motions are referred to as glide or slide, spin, and roll.^4,14 Because these are passive movements at the actual joint level, they are sometimes referred to as arthrokinematic motions. Accessory and physiologic joint motions occur together during active ROM. If full accessory motion does not occur, there will be a limitation in normal physiological cardinal plane movements. However, accessory joint motion cannot be selectively recruited, meaning that a patient cannot selectively perform joint roll, glide, or spin independently on their own.⁴ The application of accessory joint motion is defined as “joint play” or “motion that occurs within the joint as a response to an outside force but not as a result of voluntary movement.”⁴

An arthrokinematic glide and an arthrokinematic slide movement are essentially the same. Gliding and sliding occurs as a specific point on one portion of the articular surface comes into contact with a series of locations on the corresponding joint surface. An analogy of this would be a car wheel sliding on ice when brakes are pushed. One part of the tire glides or slides across a series of locations of the ice surface. When the elbow is flexed doing a biceps curl, the convex olecranon rolls anteriorly and glides or slides posteriorly on the relatively fixed concave trochlea of the distal humerus.

The arthrokinematic movement termed spin occurs when a portion of one joint spins or rotates, clockwise or counterclockwise, around a stationary longitudinal axis. An example of this is when a forearm goes through the motion of supination and pronation. At the radiohumeral joint, the radial head will spin on the capitellum of the distal humerus.

Rolling occurs when multiple points of contact on one joint surface come into contact with multiple points of contact on the corresponding joint surface. The analogy for this movement would be a car tire driving normally where the tire surface makes contact with a different portion of the road. In the human, this occurs as the convex distal femur rolls forward and glides on the concave tibia when the person moves from a seated to a standing position.

JOINT CONGRUENCY AND POSITION

The concept of joint congruency and the terms close-packed and loose-packed, referring to joint position, are pertinent to the discussion of various grades of mobilization. Congruence refers to articular position with regard to concave and convex joint surfaces. A joint is congruent when both articulating surfaces are in contact throughout the total surface area of the joint.4,14 However, the study of arthrokinematics (joint movement) states that joints are rarely in total congruence. As joints move, the accessory motions of glide or slide, spin, and roll alter total joint congruence.

MacConaill and Basmajian¹⁴ have described close-packed positions as the most congruent positions of a joint,^4,14 where the joint articular surfaces are aligned and the capsule and ligaments are taut and joint volume is minimal (Fig. 15-1). Generally, a close-packed position is used for testing the integrity and stability of ligaments and capsular structures. However, the close-packed position described by MacConaill and Basmajian¹⁴ is not used for mobilization techniques. The close-packed position is one of stability. When the elbow and knee are fully extended, the ligaments and joint capsule are taut, allowing no freedom of movement. Therefore the knee and elbow in extension serve as two excellent examples of joints in the close-packed position.

Any joint position other than the close-packed position is a loose-packed position. The position in which the joint capsule and ligaments are most relaxed, loose, and allow the maximum amount of joint play is referred to as the joint’s resting position.⁴ When the knee joint is flexed to 30°, the intracapsular space is increased and supporting ligaments become more relaxed. The loose-packed position is ideal for applying joint mobilization techniques, but painful, stiff, and dysfunctional joints are rarely in ideal resting positions for the application of joint mobilization. Table 15-1 lists resting and close-packed positions of major joints in the human body.¹⁶ If a joint has a limitation of arthrokinematic movement in which the close-packed position cannot be achieved, ground reaction forces and gravitational forces are not distributed through the joint in an optimal manner, thus additional stress and work has to be taken up by the periarticular muscles. If this dysfunctional movement pattern continues, a condition of muscle overuse can ensue.

CONVEX–CONCAVE RULE

Anatomically, all articular surfaces are either convex or concave,4,21 although the surfaces of some joints are not overtly of either shape. In these cases, fibrocartilage enhances and modifies the contour of the joint surfaces. On the convex joint surface, more cartilage is found at the center of the surface; on a concave joint surface, more cartilage is found at the periphery.⁴

The convex–concave rule specifically states, “When the concave surface is stationary and the convex surface is moving, the gliding movement in the joint occurs in a direction opposite to the bone movement.”⁴ Conversely, if the convex surface is fixed while the concave surface is mobile, the gliding motion occurs in the same direction as the bone movement.⁴ This occurs because the convex bone surface always maintains an axis of rotation during joint motion (Fig. 15-2). The concept of accessory joint motions (glide or slide, spin, and roll), as they apply to joint congruency and the convex–concave rule, is clearly illustrated by MacConaill’s classification of accessory movements (Fig. 15-3).

MOBILIZATION GRADES

Maitland¹⁷ describes five grades of physiologic and accessory joint motions used in mobilization (Fig. 15-4). The terms velocity, oscillation, and amplitude of movement describe the degree of force and rate of motion used during any of the grades of mobilization, as follows:

In general terms, a grade I or II small amplitude oscillation is used to treat pain or when joint motion produces pain.4,21 Therefore mobilization in grades III and IV are used to treat joint restrictions.^4,21

Translational movements during joint mobilization techniques can be performed in one of two planes. Joint mobilizations can be performed perpendicular or parallel to the treatment plane. The treatment plane is described as a line running perpendicular to, or at a right angle to, a line running from the axis of joint rotation in the convex surface to the center of the concave articular surface.¹² A translational joint mobilization technique (glide) is one in which the articulating surface glides along a line parallel to the treatment plane.

Traction also is used as a manual therapy technique either by itself or along with various mobilization techniques (Fig. 15-5). A traction technique is a joint mobilization technique that translates one articular surface in a perpendicular direction away from the treatment plane. Traction can be classified in grades or stages.^12,17 Generally, grade I or stage I traction is used for relief of pain and to minimize compressive joint forces during mobilization. The term piccolo traction describes a stage I traction technique. The force used to deliver grade I traction is not enough to actually separate the joint surfaces, but rather only neutralizes joint pressure.⁴

As a general rule, distraction techniques cannot stretch or increase length of any specific portion of a joint cavity; rather they are for general overall mobility. Translational glide techniques are used to specifically treat a single portion or restricted joint capsule or tight structure. The term slack refers to the amount of normal looseness found in nonpathologic joint capsules and describes various degrees of joint tightness with stage II and III traction. Stage II traction is defined as being able to “take up the slack” in the capsule of the joint being stretched; it is commonly used to treat pain. Stage III traction is more substantial and actually involves stretching of the soft tissues. These techniques are performed to stretch out joint tightness.

JOINT END-FEEL

There are various qualities of joint tightness or “play” during the application of passive joint movements. Three types of end-feel have been defined in normal, nonpathologic joints.7,16 Bone to bone end-feel refers to a sudden, hard, nonyielding sensation felt at the end ROM. Generally, the end-feel is not painful. Terminal elbow extension in which the olecranon process contacts the olecranon fossa provides an example of a sudden bone-to-bone end-feel.

Another normal end-feel is soft-tissue approximation. This type of joint end-feel is characterized by a “yielding compression” typically encountered with knee or elbow flexion.¹⁶ The end-feel that occurs with soft tissue approximation results from muscular tissue compression during joint flexion. The hamstring and calf muscles buttress and compress against each other during knee flexion, delivering a soft-tissue approximation end-feel.

The third normal joint end-feel is described as a hard or springy-tissue stretch. The characteristic feature of this end-feel is “elastic resistance” or “rising tension.”¹⁶ This type of end-feel is the most common normal feel at the end range of joints. Terminal knee extension and wrist flexion provide a springy stretch that defines tissue stretch.

The PTA must experience normal joint end-feel and be able to accurately identify distinguishing characteristics between bone-to-bone end-feel, soft-tissue approximation, and tissue stretch.⁷ The PTA performing mobilization will undoubtedly encounter abnormal joint end-feel, and its precise identification requires considerable didactic and hands-on experience.⁷

The first type of abnormal end-feel is muscle spasm. The major component is pain accompanied by a sudden halt of movement that prevents full ROM.4,7,16

In springy block, or internal derangement, full motion is limited by a soft or springy sensation occasionally accompanied by pain. If a meniscus is torn in a knee, frequently the cartilage becomes caught in the joint, preventing terminal knee extension and its characteristic normal tissue stretch and feel.

In an empty end-feel, motion is very limited by significant pain without muscle spasm. Clinically, this end-feel is not characterized by any mechanical block or restriction.

Another abnormal end-feel is described as loose end-feel.⁴ Its primary feature is joint hypermobility, with no resistance typically felt at the end ROM that signifies extraordinary joint looseness.

A capsular end-feel¹⁶ is analogous to a normal tissue stretch, but the elastic resistance is encountered before the normal ROM. This end-feel is related to a capsular restriction.¹⁶

Table 15-2 lists various normal and pathologic end-feels and examples of each.²

CAPSULAR AND NONCAPSULAR PATTERNS

The PTA must be aware that certain limitations of motion can be caused by lesions specific to the capsule or synovial tissues of a joint. All joints controlled by muscle activity possess a characteristic “capsular pattern of proportional limitation.”¹⁶ Each joint has its own capsular pattern, which is generally universal among all. For example, in the shoulder joint, the capsular pattern “involves external rotation as the most limited movement, abduction as less limited, internal rotation still less limited, and flexion as the least limited movement.”^4,7 Any “characteristic pattern of limitation” is called a capsular pattern.

If a lesion causes a restriction of movement that does not correspond to a characteristic, predetermined capsular pattern, it is called a noncapsular pattern.4,16 Cyriax⁷ has identified three possible causes of noncapsular pattern restrictions:

Table 15-3 lists joint restrictions from noncapsular patterns.²

INDICATIONS AND CONTRAINDICATIONS FOR MOBILIZATION

Patient safety should always be considered when applying joint mobilization or manipulation techniques. Cautions or contraindications for joint mobilization and manipulation are listed in Table 15-4 and Box 15-1.¹⁵ Extreme caution must be employed before applying mobilization techniques in the early stages after trauma or surgery or during times of immobilization. Although pain is an indication for the use of mobilization, care must be taken to avoid retarding or impairing the sequence of tissue healing during the acute inflammatory phase.

Vascular elements Neurological elements Soft tissue elements Metabolic disease Bone disease, such as osteoporosis Systemic disease/condition Asthma, hemophilia, pregnancy Inflammatory diseases Acute active inflammation such as rheumatoid arthritis or inactive inflammatory disease Medications patient may be taking

CLINICAL APPLICATION OF JOINT MOBILIZATION

Safe and effective joint mobilization requires the patient to be placed in a very comfortable position and the specific joint to be mobilized to be placed in a maximal resting or loose-packed position.¹⁴ Before mobilization is applied, patient compliance and relaxation can be facilitated by the judicious use of moist heat, ultrasound, transcutaneous electrical nerve stimulation (TENS), electrical muscle stimulation, ice, exercise, and the timely use of any physician-prescribed analgesics or muscle relaxant medications. If pain is the predominant feature of the joint to be mobilized, grade I and II mobilization can be employed safely.

Oscillations help modulate or minimize pain when using grade I and II mobilization. Manually applied joint oscillations occur at a rate of 1 to 3 per second, or 60 to 180 per minute.4,17 Typically, a mobilization grade technique is applied for 20 to 60 seconds only four or five times. This is recommended for the treatment of painful conditions on a daily basis or until pain is reduced. These smaller amplitude mobilization techniques are used to stimulate mechanoreceptors within the joint that can limit pain perception transmission at the spinal cord or brainstem level through a hypoalgesic response mediated by the noradrenergic descending pain pathways from the periaqueductal gray area.²²

It is not uncommon to perform grade I and II mobilizations to a joint for purposes of decreasing pain before more aggressive mobilization techniques to gain motion. Some irritable conditions require a short bout of smaller oscillation techniques before techniques designed to gain mobility.

A program of mobilization is carried out two to three times per week for the treatment of joint restrictions.⁴ Piccolo or stage I traction can be used simultaneously with grade I or II mobilization or by itself to reduce pain and neutralize joint pressure. When the limitation of joint motion is greater than the complaints of pain, grade III and IV mobilization can be used to help stretch the capsule and soft tissues around the joint.

The pathologic condition of the joint to be mobilized must be thoroughly understood before applying any mobilization technique. For example, it is critical to avoid stressing the anterior capsule of the shoulder after an anterior dislocation, although mobilization to improve shoulder abduction may be warranted.²¹

In every case of joint mobilization, the PTA must constantly observe and document the patient’s tolerance, pain response, and swelling to determine whether to halt the procedure, reduce the grade of motion, or consult with the PT about advancing the grade of mobilization.

As stated in the beginning of this discussion, the PT is responsible for delegating selected peripheral joint mobilization techniques to the PTA. Although peripheral joint mobilization beyond active and passive ROM is an area of treatment not usually delegated to the PTA, understanding peripheral joint mobilization techniques and having an awareness of rudimentary concepts and principles of mobilization provide the PTA with a broad understanding of the rationale for the application of certain techniques.

MOBILIZATION EVIDENCE

When assessing the medical literature, there is very little in regard to high-level evidence via randomized controlled clinical trials (RCTs) assessing effectiveness of joint mobilization techniques. The studies that are described next are those that have a higher level of evidence via either number of participants, prospective, randomized designs, and described inclusion/exclusion criteria.

There are mixed reviews in the ankle. Lin and colleagues¹³ recently reported that incorporation of large amplitude grade III anterior-posterior glides to the talus for 4 weeks did not enhance their outcomes at 24 weeks following ankle fractures. This is in direct contradiction to Green and coworkers⁸ who used an experimental group given anteroposterior joint mobilizations to the talus following an acute ankle sprain and a control group that was treated with rest, ice, compression, and elevation (RICE). Following the intervention period the experimental group required fewer treatments, had greater improvements in ROM at the ankle, and greater increases in stride speed, indicating that the addition of joint mobilizations had a positive impact on outcomes.

In the hip, Hoeksma and associates¹⁰ proved in a single-blind, RCT of 109 patients with osteoarthritic hips that manual therapy resulted in 81% success rates for the experimental group as compared with only 50% in the control group. The experimental group demonstrated better outcomes in regard to pain, stiffness, hip function, and ROM following 5 weeks (9 sessions) of manual therapy treatments of hip joint distraction followed by a hip traction manipulation. These beneficial changes remained even after 29 weeks.

In the shoulder, Senbursa and colleagues¹⁹ used a RCT to compare effectiveness of two treatments for shoulder impingement—soft tissue and joint mobilization or independent exercise program. Thirty patients with impingement were randomized into one of the treatment approaches and followed for 3 months. The manual therapy group received a prescription of 12 sessions of joint mobilization. The experimental group demonstrated significant decreases in pain and increases in ROM. Conroy and Hayes⁶ examined the usefulness of joint mobilizations on 14 patients with impingement syndrome. Random assignment was to an exercise program alone or an exercise program with joint mobilizations. The results were mixed, with the mobilization group demonstrating less 24-hour pain, and less pain with a subacromial compression test, but no differences in ROM and function.

Bang and Deyle³ assessed the comparison of supervised exercise versus supervised exercise combined with manual therapy to the upper quarter in those with impingement syndrome. The manual therapy approach they used consisted mainly of grade I to V oscillatory caudal glides of the glenohumeral joint in varying degrees of flexion and abduction. Bang and Deyle³ found significant improvement in pain reduction, function, and strength in those that received manual therapy in addition to supervised exercises. More recently, Manske and colleagues¹⁸ used an RCT of stretching versus stretching plus posterior shoulder capsular mobilizations to assess for efficacy in treating a tight posterior shoulder. The main outcome measure was internal rotation motion loss. Using 39 randomly assigned subjects with at least a 10° loss of internal rotation, it was found that the addition of posterior shoulder joint mobilization to a stretching program resulted in trends towards increased motion.

A Cochrane review performed by Gross and colleagues⁹ assessed mobilization and manipulation in patients with mechanical neck disorders. Outcomes were based on pain relief, functional improvement, or overall disability improvement. Studies including single session and multiple session manipulative therapy. Some in the presence of other treatment modalities showed little to no benefit for patients with acute, subacute, and chronic neck disorders. Mobilization alone was found to have similar results based on four randomized controlled trials in which mobilization was tested against cold pack, TENS, and ultrasound, among others. Mobilization and manipulation combined in a treatment approach also found little evidence to support their use for pain relief and improvement in function. Mobilization and manipulation with the addition of exercise was found to have positive results for the three outcome criteria. Though this is encouraging for those patients suffering with acute to chronic pain in the cervical spine, the authors also noted studies that compared manipulation plus exercise to exercise alone with little difference noted between these groups.

A review of literature done by Hurwitz and associates¹¹ looked at studies examining the use of mobilization and manipulation in the management of neck pain and headaches. Neck pain was broken down into acute, and subacute or chronic neck pain. In the studies reviewed, the authors found that mobilization provided some statistically significant decreases in pain when compared with other treatment options. Manipulation of the cervical spine in patients experiencing subacute and chronic neck pain as well as tension-induced headaches showed subjective improvements compared with other therapies, however; the authors also noted the risks involved with cervical manipulation. These risks included paralysis and even death, with rates of injury occurring in 5 to 10 per 10 million manipulations.

In a study investigating the safety of mobilization to the thoracic spine, Sran and coworkers²⁰ used 12 cadavers to determine the in vitro effects of spinal mobilization to the sixth thoracic vertebra. Loading of the spinous process of T6 was performed using mechanical compression to the point of failure. The average amount of force to failure in the cadaver models was 479 ± 162 newtons (N). These results varied significantly when compared to the in vivo effects of mobilization, where two physiotherapists applied an average load of 145 ± 38 N. The amount of force then applied in this study showed that posterior to anterior mobilization when applied with care has a fairly significant margin of error before fracture occurs. The authors summarized the findings to be clinically relevant in cases where the patient needing mobilization, at least in the thoracic spine, may have bone density issues leading to use of decreased force of mobilization or mobilization being contraindicated.

Management of low back pain is difficult and a very common problem in the patient population of the PT or PTA. The use of manipulation or mobilization to address the dysfunction associated with the low back is becoming increasingly popular. A systematic review of literature provided by Bronfort and colleagues⁵ showed that manipulation and mobilization of the spine did have some evidence to support its use in the management of acute and chronic low back pain. In acute episodes the authors were able to conclude manipulation was better suited to relieve pain than other treatment techniques, including mobilization and diathermy. For chronic low back pain the authors were able to conclude that manipulation with the addition of strengthening exercises had evidence to support its use in the reduction of pain and disability.