Adjustive localization refers to the preadjustive procedures designed
to localize adjustive forces and joint distraction. They involve the application of physiologic and unphysiologic positions, the reduction of articular “slack,” and the development of appropri- ate patient positions, contact points (CPs), and adjustive vectors. These factors are fundamental to the development of appropriate preadjustive articular tension and adjustive efficiency. Attention to these components is intended to improve adjustive specificity and to further minimize the distractive tension on adjacent joints. The proper application of these principles should maximize the doctor’s ability to focus his or her adjustive forces to a specific spinal region and joint.
physiologic and unphysiologic Movement
Knowledge of the physiologic movements (normal coupled move- ments) of the spine and extremities is important in the pro- cess of determining how to localize and apply adjustive therapy. Localization of adjustive forces depends on an understanding of the normal ranges of joint movement and how combinations of movement affect ease and range of joint movement. Each spinal region and extremity joint has its own unique range and patterns of movement. Knowing the ranges and patterns of movement allows the doctor to know what combination of movements is necessary to produce the greatest range of movement and what combination is necessary to limit movement.
Figure 4-26 Effects of an adjustive force applied in a P-A direction along the disc plane.
Prone: Segmental extension Disc plane
vector
Figure 4-27 Hypothetical effects of an adjustive thrust applied in a P-A and I-S vector along the facet planes.
Longitudinal distraction Prone: Segmental Flexion Facet plane
The spine can flex, extend, laterally flex, and rotate, but in combination, these movements can act to either limit or increase movement. Performance of movement in one plane limits movement in another plane; flexion of the spine limits the amount of lumbar rotation, and lumbar rotation limits the amount of flexion. An additional coupling of motion in a third plane can combine to further restrict or enhance the ROM. For example, the greatest range of combined lumbar rotation and lateral flexion is achieved if rotation and lateral flexion are exe- cuted in opposite directions and coupled with extension instead of flexion.
Combined movements that allow for the greatest total com- bined range are referred to as physiologic movements, and com- bined movements that lead to limited movement are referred to as unphysiologic movements. Right lateral flexion combined with left rotation and extension is an example of physiologic movement in the lumbar spine. Right lateral flexion combined with right rotation or flexion is an example of unphysiologic movement.
Unphysiologic movements bring the joints to positions of ten- sion earlier in their ROM, limiting their overall ROM. Positioning sections of the spine in unphysiologic postures during the applica- tion of adjustive therapy is a strategy referred to as joint locking.409
Application of this procedure helps focus the adjustive forces to the affected region or joint and minimizes mobility at adjacent joints. When adjacent spinal regions are placed in unphysiologic positions, a block of resistance may be created superior or inferior to the joint to be adjusted, establishing earlier preadjustive ten- sion. Joints placed in their unphysiologic positions have greater impact between joint surfaces, which may decrease the likelihood of paraphysiologic joint movement and gapping at those joints.
The region and motion segment to be adjusted is placed in the transition area between unphysiologic motion and physio- logic motion or between sections placed in unphysiologic lock- ing (Figure 4-28). The joints to be adjusted must have sufficient slack remaining so that the adjustive thrust may induce gapping or gliding within the joint’s physiologic range. If an adjustive thrust is delivered against a joint placed in its close-packed posi- tion, there is a greater risk of inducing joint injury. Placing joints in unphysiologic positions may be especially valuable in circum-
stances in which clinical joint instability is suspect at adjacent levels.
reduction of articular slack
Articular slack refers to the joint play (JP) present in all synovial
joints and their periarticular soft tissues. Although it is a normal component of joint function, available slack should be reduced during or before delivery of an adjustive thrust to improve the likelihood of inducing joint cavitation. Reducing articular slack helps isolate tension to the specific periarticular soft tissues that may be limiting JP and impeding joint motion. The removal of articular slack and the development of preadjustive tension also help focus the adjustive thrust to the desired spinal level or extremity joint. The energy and force generated by adjus- tive thrusts may be dissipated into superficial soft tissue and adjacent articular soft tissue if preadjustive tension is not first established.410,411
The doctor may reduce articular slack by passively distracting the involved spinal region or joint or by altering patient positions to move the joints from their neutral position toward their elastic barrier. Joint distraction induced by the doctor may be developed by the gradual transfer of body weight through the adjustive con- tacts or by directing tractional forces through the adjustive con- tacts. The degree of preadjustive tension is gauged by the doctor’s sense of joint tension and by the patient’s response to pressure. Excessive traction or compression of joints during the application of adjustive procedures can lead to jamming of joints, uncomfort- able contacts, and patient splinting. It is common for chiropractic students to overdo articular slack reduction and preadjustive ten- sion when first learning adjustive techniques.
Lighter contacts and less preadjustive tension are necessary when patient discomfort and splinting are encountered. Joints with limited mobility need less movement to reduce articu- lar slack and are often adjusted closer to their neutral positions. Joints with greater flexibility usually necessitate patient positions that move the joint from neutral positions toward the elastic barrier.
Patient Positioning. Preadjustive joint tension and localiza- tion are significantly affected by patient placement and leverage. Localization of adjustive forces may be enhanced by using patient placement to position a joint at a point of distractive vulnerability. Locking adjacent joints and positioning the joint to be adjusted at the apex of curves established during PP enhance this process (Figure 4-29). Joint localization and joint distraction may be fur- ther enhanced if forces are used to either help (assist) or oppose (resist) the adjustive thrust. Assisted and resisted patient positions refer to principles involved during the adjustive setup and devel- opment of preadjustive tension.
Assisted and Resisted Positioning. The notion of applying assisted and opposing forces during the performance of manip- ulation was first described relative to thoracic manipulation by the French orthopedist Robert Maigne.412 In the chiropractic pro-
fession, Sandoz24 was the first to describe similar terms. Sandoz
proposed using the terms assisted and resisted to describe patient positions that either assist or resist side posture (SP) lumbar adjus- tive thrust.24 Both methods are used to improve the localization of
preadjustive tension. Their application is based on the mechanical Transition point
Figure 4-28 The joints above the level to be adjusted (L3 and L4) are placed in unphysiologic position (flexion, left rotation, and right lateral flexion) to develop locking of the joints above the level to be adjusted.
principle that the region of maximal tension will be developed at the point of opposing counter-rotation.413
Assisted and resisted patient positions are distinguished from each other by the positioning of vertebral segments relative to the adjustive thrust. In both circumstances, the trunk and verte- bral segments superior to the adjustive contacts are prestressed in the direction of desired joint movement. In the assisted method, the contacts are established on the superior vertebral segments, and movement of the trunk and the thrust are in the same direc- tion (Figure 4-30, B). Resisted procedures use patient positions in which the segments superior to the adjustive contact are pre- stressed in a direction opposing the adjustive thrust. In the resisted method, the contacts are established on the lower vertebral seg- ments, and the direction of adjustive thrust is applied opposite the direction of trunk movement (see Figure 4-30, A).
Sandoz24 has suggested that resisted positions bring maximal
tension to the articulations superior to the established contact (e.g., contact at the L3 mammillary inducing tension at the L2-3 motion segment and above) and assisted positions bring maximal tension to the articulation inferior to the established contact (e.g., L2 spinous contact inducing tension at the L2-3 motion segment and below). In the assisted method, the area of countertension is inferior to the point of contact because the inferior segments are
stabilized or rotated in a direction opposite the adjustive thrust (see Figure 4-30). In the resisted approach, the site of counter- tension is superior to the point of contact because the segments above the point of contact are rotated in a direction opposite the adjustive thrust (see Figure 4-30). Research by Cramer and co- workers265 has demonstrated that side posture-resisted lumbar
mammillary push adjustments induce positional and postadjust- ment gapping in the articulations superior to the level of contact. In principle, either method can be used to induce the same joint motion within the same articulations. With assisted patient posi- tions, the thrust is oriented in the direction of joint restriction; with resisted patient positions, the thrust is directed against the direction of joint restriction.
Assisted and resisted patient positions have been most fre- quently discussed relative to the development of rotational tension of the spine. In theory, the same methods and principles may be applied to treat dysfunction in lateral flexion or flexion and exten- sion. To treat a loss of right lateral bending in the lumbar spine using the assisted method, the patient is placed on the right side with a roll placed under the lumbar spine to induce right lateral flexion. A contact is then established over the left mammillary of the superior vertebra, with an adjustive vector directed anteriorly and superiorly (Figure 4-31). To treat the same restriction with a resisted method, the same patient postioning should be main- tained, but the left mammillary process of the inferior vertebra is contacted with a thrust delivered anteriorly and inferiorly (see Figure 4-31). Although both techniques are directed at distracting the left facet joints, one is assisting and the other is resisting the direction of bending.
To treat a loss of lumbar flexion with a side posture-assisted method, the patient should be placed on either side and segmen- tal flexion induced, the superior vertebrae of the involved motion segment should be contacted, and the thrust should be anterior and superior. Conversely, without changing PP, the same restric- tion could be treated with a resisted method by simply contacting the lower vertebrae and thrusting anteriorly and inferiorly (Figure 4-32). The same principles described for flexion can easily be applied to treat an extension restriction, the only difference being the prestressing of the patient into segmental extension.
When applying side posture adjustive thrusts in the treatment of lateral flexion, flexion, or extension, it is typically less stressful to the doctor’s wrist and shoulder to couple P-A thrusts with an I-S vector, as opposed to a coupled superior-to-inferior vector. The superior-to-inferior vector induces a posture of wrist extension and internal shoulder rotation that is uncomfortable and possibly injuri- ous. Therefore, lateral flexion and flexion adjustments may be more safely and comfortably delivered with assisted patient positions and extension adjustments delivered with resisted patient positions.
The principles presented for assisted and resisted lateral flexion and flexion-extension side posture adjustments are potentially lim- ited by the same biomechanical issues discussed previously relative to prone thoracic adjustments. Biomechanical research indicates that it is very unlikely adjustive contacts can establish effective tension with underlying bone, fascia, or muscle.269 In this context it seems
unlikely that adjustive vectors directed superiorly or inferiorly will generate forces helpful in assisting in the production of lateral flexion or flexion-extension movements. It seems more plausible
Figure 4-29 Proper patient positioning is necessary to develop appro- priate preadjustive joint tension. a, Sagittal plane movement (flexion) and separation of the posterior element of the joint. b, Coronal plane movement (lateral flexion) and separation of the joint away from the table (left facet joints and disc). C, Transverse plane movement and develop- ment of counter-rotational tension and gapping of the left facet joints.
A
B
that attention to PP and factors that assist in deforming the spine in lateral flexion or flexion-extension would be potentially most effective.
Although the classification scheme of assisted and resisted patient positions is useful for contrasting different methods, it does create a possible void for those procedures in which both hands establish adjustive contacts and both deliver opposing adjustive thrusts. Counterthrust procedures, commonly applied during rotational spinal adjustments, do not conform to the strict definitions of assisted or resisted PP because these terms are defined relative to the delivery of one thrust, not two. In methods applying counterthrust techniques, both arms thrust; one arm establishes an assisted position and thrust as the other develops a resisted position and thrust. Based on the previous guidelines, they do not fit either category. To distinguish them
from single-thrust patient positions, we suggest referring to them as counterthrust procedures (Figure 4-33).
Neutral Positioning. Neutral patient positions refer to circum- stances in which the patient and articulations are left in a relatively neutral position during the delivery of an adjustive thrust. Any preadjustive reduction of articular slack is established through the doctor’s contacts without significant alterations in PP (Figure 4-34). Neutral positioning may be practical in some procedures such as prone spinal adjustive positions but impractical in others such as side posture rotational adjustments in which rotational leverage works to the doctor’s advantage.
Principles of Patient Positioning. To take advantage of the potential increased specificity and efficiency that modifications in PP offer, the doctor must be aware of the various options available and the principles that underlie them. Although one approach is
A B
4-30A, B Figure 4-30 positioning with spinous contact established on the superior vertebra. Both procedures are applied to produce left rotation.a, Resisted patient positioning with mammillary contact established on the inferior vertebra. b, Assisted patient
Assisted Resisted
Figure 4-32 Adjustment for loss of flexion using resisted (inferior vertebra) or assisted (superior vertebra) methods.
Figure 4-31 Adjustment for loss of right lateral flexion. With a resisted method, the contact is established on the left mammillary process of the inferior vertebra. The assisted method incorporates a contact estab- lished on the left mammillary process of the superior vertebra.
Resisted
not necessarily superior to the other, each method has unique attri- butes that may make it more appropriate in certain circumstances. To make the appropriate distinction and effectively deliver adjust- ments, the doctor needs a clear understanding of each method’s unique mechanical characteristics and differences. For example, a thrust delivered against the left L3 mammillary of a patient lying on the right side with shoulders in neutral may not have the same mechanical effect as in the patient whose shoulders are rotated toward the table into left rotation.
With the patient in the neutral position, the thrust against the left L3 mammillary is typically and traditionally applied to induce right rotation of L3 relative to L4 and the segments below (Figure 4-35). If the same thrust is delivered with the patient’s shoulders rotated into left rotation (resisted position), maximal tension and cavitation may be induced in left rotation at the ipsilateral articulations above (L2-3 and superior). If the doctor wishes to induce right rotation at the L3-4 motion segment with an adjustive technique that involves shoulder counter-rotation and a mammillary contact, the patient should be placed on the opposite side (left) with a mammillary contact established at L4 instead of L3 (Figure 4-36).
adjustive specificity
Adjustive specificity describes the degree to which an adjustment is
localized to a specific spinal region or joint. Historically the chi- ropractic profession has emphasized the value and application of methods believed to focus maximal effect in one joint. Application of the principles of PP and joint localization maximizes the potential for specific effects, but does not ensure that adjustive set- ups and thrusts will produce movement only at the desired level. The spine is a closed kinetic chain, making it highly unlikely that spinal movements can be induced at one joint at a time.264,269 Any
adjustive thrust will have some effect on the other components of the three-joint complex and the joints superior to and inferior to the contacted vertebrae.264
The adjustive objective is not to eliminate all adjacent move- ment but to stress the skills that increase the probability of pro- ducing regional and focused joint cavitation while minimizing movement and tension at unwanted spinal regions and adjacent joints.
Ross, Bereznick, and McGill269 conducted some groundbreak-
ing work evaluating the level of applied adjustment and the level of induced joint cavitation. They were able to localize the level of thoracic and lumbar joint cavitations by fixing accelerometers to the skin over the spinal column and measuring the relative time it took for cavitation-induced vibrations to reach each accelerom- eter. Lumbar adjustments produced multiple levels of cavitation in most cases (2 to 6). The average cavitation site was 5.29 cm off the target level (at least one vertebra away) with a range of 0 to 14 cm. In the thoracic spine, the average cavitation site was 3.5 cm off the target site, with a range of 0 to 0.95. Their research indi- cates that the tested procedures did not produce the frequency of targeted joint-level joint cavitations desired. Lumbar SMT was accurate approximately half the time. However, because lumbar adjustments were associated with multiple cavitations, at least one cavitation also typically emanated from the targeted joint. In the thoracic spine, SMT appears to the more accurate. Other studies evaluating cervical rotational adjustments and side posture lumbar
4-33 Figure 4-33 A counterthrust procedure applied to treat a lumbar right rotation restriction.
Segmental contact points
Figure 4-34 Prone thoracic bilateral thenar transverse adjustment applied to induce segmental extension with neutral patient positioning.
and SI adjustments also indicate less precision in producing cavi- tations to side or level to targeted joint.267,268
Research evaluating HVLA adjustive specificity depends on the chiropractor’s initial judgment of which joint is being targeted. This depends on the accuracy of the segmental contacts, the methods the chiropractor applies, and the biomechanical assumptions he or she has about the applied adjustment. The chiropractic profession has a history of assuming that adjustive contacts can be focused to one ver- tebra. It is also common to assume that the joint below the level of vertebral contact is the joint being targeted for treatment (adjusted). There are some presumptions in this model that seem improba- ble. First, it is unlikely that surface adjustive contacts can be precise enough to contact just one vertebra. In addition, surface contacts do not appear capable of hooking or binding to underline vertebra and