Issues in determining treatment effectiveness of manual therapy.

[Fitzgerald GK McClure PW, Beattie P, Riddle DL. Issues in determining treatment effectiveness of manual therapy. Phys Ther. 1994;74:227-233.]

Key Words: Decision making, Manual Therapy.

The use of manual therapy is considered by many therapists to be an important component in evaluation and treatment of musculoskeletal disorders.[1] The principles of patient evaluation and treatment using manual therapy are now included in most entry-level physical therapy curricula.[2] Additionally, numerous continuing education courses advocate the use of manual therapy.

A number of studies investigating the effectiveness of manual therapy have been published in the past two decades.[3-19] Some forms of manual therapy, such as spinal manipulation techniques, have been found to be beneficial for some patients.[20] However, problems with experimental designs in many studies have made it difficult to make definitive conclusions concerning the effectiveness of manual therapy.[6,21,22]

Many barriers exist that make it difficult to design experimental studies that examine the effectiveness of manual therapy. These same barriers interfere with the production of case reports and all forms of clinical documentation. Operationally defining both the manual therapy procedures and the phenomena that are evaluated and treated with these procedures can be a difficult task. There are philosophical differences in the outcome measures used by manual therapists to determine treatment effectiveness. For example, some manual therapists describe pain in response to passive motion as an important outcome,[23] whereas others feel that the degree of motion available is most important.[24,25]

There are individual differences in the application of treatment techniques among therapists. Although two therapists may decide to use the same technique, the amount and direction of force applied, the duration of treatment, and decisions to change techniques during treatment may differ, These differences may result in different treatment outcomes. Thus, it is difficult to create, research protocols that compare the effect of specific treatments administered by different therapists.

Treatment plans for patients with musculoskeletal problems typically consist of many procedures, such as patient education and use of physical agents, that are not classically considered to be manual therapy. When manual therapy is combined with other treatments, it can be difficult to determine the extent to which each type of treatment affects outcome.

Despite these problems, we believe that clinicians can plan and implement research to determine the effectiveness of manual therapy and that they can better describe this approach in case reports. Careful consideration of important issues such as operationally defining treatments, adequately describing clinical decision-making strategies, patient selection, and using logical measurement procedures for outcome assessment can enhance the quality of manual therapy research. The purposes of this article are to discuss these issues and to identify strategies for clinicians to evaluate the effectiveness of manual therapy.

Operational Definitions

The term "manual therapy" represents a variety of evaluation and treatment procedures. Manual therapy may include massage, passive and active-assisted range of motion, joint distraction or traction, and joint mobilization and manipulation.[1] Proprioceptive neuromuscular facilitation (PNF) and manually resisted strengthening exercises could also be classified as manual therapy procedures. Because the term "manual therapy" could represent a variety of treatments, it is important that specific procedures used in treatment are operationally defined. Operational definitions would clarify how treatments were implemented and would allow others to replicate the treatments in clinical practice or in clinical research.

An operational definition of manual therapy should include several items. The specific technique or techniques used during treatment should be clearly described. Descriptions of treatment should include the position of the patient during treatment, placement of the therapist's hands, and the direction in which forces are applied by the therapist. When passive techniques are used, the nature of the applied force should be described. This description may include the use of thrust versus nonthrust techniques, or the use and grade of oscillatory motions. The degree of force may also be described as applying "pain-free" techniques versus "pain to tolerance" techniques. When treatment techniques involve manually resisting voluntary muscle contractions, the type and vigor of muscle contraction being resisted should be described. For example, isometric, concentric, or eccentric contractions could be resisted against submaximal or maximal effort. The frequency and duration of manually applied forces should also be described (eg, two oscillations per second for 60 seconds).

Another critical operational definition is the criteria that clinicians use to modify manual procedures during the course of treatment. Many authors[23,26-28] advocate continual reassessment of the patient's condition and altering treatment techniques according to the patient's response to treatment. Deciding when and how to alter treatment requires that rules be established that guide the decision making, based on measured responses to treatment. Establishing these rules can be a difficult task when doing manual therapy research. One problem is that some of the expected responses to treatment that are said to serve as a basis for altering treatment may be difficult or impossible to measure. For example, changes in "soft tissue tension" and the amount of resistance to motion that the examiner "feels" have been described as criteria for altering the manual therapy protocol.[29] The question raised here is whether one can measure change in either of these factors? If we are unable to measure changes in these factors, or describe them in a manner that allows others to fully understand them, then we have not sufficiently established a set of criteria for altering treatment.

Attempts at establishing criteria for altering treatment should be directed toward measurable factors that may be affected by treatment. Some of these factors may include changes in pain, joint motion, posture, and functional activity. Deciding when and how to change the treatment would be based on how levels of these factors varied during treatment. We can use changes in joint motion as an example of one set of criteria. The criteria to continue treatment as planned may be based on an increase of 5 to 10 degrees of joint motion over two treatments. The criterion for increasing the intensity of treatment (increasing force application, frequency, or duration of treatment) may be stated as no measured change in joint motion in two treatments. The criterion for selecting a different technique or approach might be that a measurable decrease in joint motion occurred in two treatments. These examples are overly simplistic because more than one factor will usually influence the decision to change treatment. The point, however, is that the decisions to alter treatment should be based on factors that can be given measurable criteria for change.

Some researchers[8,18] have limited the descriptions of treatment techniques and the progression of treatment to "as described by" some author's approach (eg, Maitland, Dutch Society for Manual Therapy). Many clinicians may use an author's approach as a guideline for treatment, but individuals probably vary in their interpretation of an "approach" and modify the treatments to suit their own personal style. The use of a technique "as described by Maitland" for one therapist may not be exactly the same for another therapist. Providing a thorough description of the actual treatment techniques and the criteria for modifying the techniques would clarify for the reader the precise treatment that was administered.

The inclusion and exclusion criteria for patient participation in clinical studies should be operationally defined. Inclusion criteria should be based on measurable factors that would suggest the treatment being studied was indicated. An example of this type of criteria will be presented later in this article. Exclusion criteria should be based on factors that may confound the study or suggest that the treatment in question is inappropriate.[6]

Considerations for Determining Outcome

Patients typically seek help from health care professionals when a disease process or injury is adversely affecting their life. Identifying factors that have an impact on an individual's life as a result of pathology or injury may guide clinicians in determining treatment effectiveness. The Committee on a National Agenda for the Prevention of Disabilities[30] has developed a conceptual model that identifies and describes factors that affect the individual as a result of pathology or injury. This model was developed from the international Classification of Impairments, Disabilities, and Handicaps (ICIDH)[31] and the work of Nagi.[32] An understanding of this conceptual model may assist clinicians in identifying factors that should be considered when assessing treatment effectiveness.

There are four concepts in the conceptual model for disability: pathology, impairment, functional limitations, and disability. The Table provides definitions and examples for these concepts. The relationship of these concepts within the context of the model can be illustrated in a patient example. A patient may be referred for physical therapy following a period of immobilization for a tibial plateau fracture (pathology). The patient exhibits a loss of knee joint range of motion (impairment). The patient's loss of full knee motion results in an inability to perform deep squatting tasks (functional limitation). The patient is a plumber, and his occupation demands that he be able to perform his job duties in confined spaces. The presence of a functional limitation such as inability to perform deep squats may prevent the patient from performing some aspects of his occupational duties (disability).

[TABULAR DATA OMITTED]

Guccione[33] has suggested that physical therapy intervention planning is directed toward changing a patient's disability by changing physical impairments and functional limitations that are related to the disability. Therefore, determining treatment effectiveness would involve assessing changes in impairment, functional limitations, and disability in response to treatment. Using the example described earlier, the clinician would monitor changes in knee range of motion, the ability to perform deep squatting activities, and the ability to perform occupational duties to determine the effectiveness of treatment.

Clinicians should recognize that other factors in addition to impairment and functional limitations may contribute to the level of a patient's disability. The mental and emotional conditions of the patient may affect the severity of disability.[32] For example, depending on an individual's emotional response to a given pain level, the patient's functional status may vary from being unaffected to being functionally incapacitated. A patient may be dissatisfied with the present work environment or situation and may not wish to return to work. There may be a lack of compliance with the treatment program in this case, to prolong the period of disability. Attempts to identify and measure mental and emotional factors such as these should be included in the evaluation process so that their influence on treatment outcome can be monitored.

The extent to which the patient perceives how the impairments and functional limitations effect his or her social roles will have an impact on the level of disability.[32] A patient whose job requires sitting at a computer terminal may not perceive an impairment such as knee joint instability as a disabling condition in terms of his or her occupational role. However, if that same patient is also an avid tennis player, knee joint instability may be perceived as a disabling condition in terms of his or her role as an athlete. Treatment outcome, in this case, would be based on athletic performance rather than work performance.

Because psychological and social factors may influence changes in the patient's condition, these factors should be considered when making conclusions regarding treatment effectiveness. The clinician would not want to make conclusions regarding the success or failure of a treatment if other factors could be identified that were responsible for effecting the patient's functional status. Pain and disability scales are available that address these factors, such as the Sickness Impact Profile (SID),[34] the MOS 36-Item Short Form Health Survey,[35] the Westhaven-Yale Multidimensional Pain Inventory,[36] and the Modified Somatic Perception Questionnaire.[37] Although it is beyond the scope of this report to provide an in-depth discussion of identification and quantification of these factors, references are available.[38,39]

Clinicians who use manual therapy techniques in treatment programs usually identify the presence of specific impairments, such as limited joint motion, then select treatment techniques that focus on resolving the impairments. Because manual therapy is guided by the identification and resolution of impairments, it would seem logical to measure changes in impairments in response to treatment to determine treatment effectiveness. Many researchers[3,4,7-9,13,18,19]] have measured changes in impairments to determine the effectiveness of manual therapy. Although conclusions regarding the effect of treatment on specific impairments can be made from these studies, the impact of the treatment on the functional status of patients may not necessarily be evident. Information concerning the impact of treatment on functional status is important because resolving functional limitations and disability is usually the goal of treatment.

Some researchers have used only measures of disability to determine the effectiveness of a manual therapy technique.[15,17] Although this approach would provide information regarding the functional improvement that occurs over the course of treatment, it would not indicate whether changes in impairments that were present occurred as the functional status changed. We would be unable to determine whether changes in functional status were the result of manual therapy or other factors. For example, a patient may have learned to adjust the way he or she performs a given activity to compensate for an existing impairment. This patient would demonstrate improved functional status, but the impairment may not have changed in response to manual treatment.

Because treatment selection in manual therapy is often based on the assumption that impairments lead to functional limitations and disability, changes in both impairments and functional status should be monitored to determine the effectiveness of manual therapy. Including both types of outcome measures would allow the clinician to determine the extent to which the treatment changed the impairment and what impact this change may or may not have had on the patient's ability to function. This information may provide a better understanding of the role of manual therapy in the treatment program. if the impairment improves as a result of treatment but functional problems are unresolved, the manual therapy technique may have been effective in changing the impairment, but other factors may need to be addressed to change the patient's functional status. Few studies have included measures of both impairment and functional ability to determine manual therapy effectiveness.[8,9,18]

Based on our experience, manual therapy techniques are used in conjunction with other methods of treatment, such as exercise, use of physical agents, and instruction in proper body mechanics, to treat patients with musculoskeletal disorders. There is some evidence that combining manual therapy with other treatments may be more effective than not using manual techniques in treatment programs for patients with musculoskeletal disorders.[10,13,19] Further study is needed to determine how manual therapy can best be applied with other forms of physical therapy. For example, what conditions would make it better to use manual techniques either before or after the other treatments? Should manual techniques be incorporated in the initial stages of rehabilitation, or is it better to wait until the patient's condition has plateaued before implementing manual techniques? These are examples of issues that need to be addressed to determine how manual techniques can best be used with other treatments for patients with musculoskeletal disorders.

Selecting Appropriate Measurement Procedures

Measurement procedures used to determine treatment effectiveness should adequately reflect changes in impairments and functional ability as a result of treatment. They should also aid the clinician in identifying and monitoring psychological factors that may influence treatment outcome. The measurements should be reliable and valid, and the methods should be clearly explained.

A variety of procedures for measuring changes in impairments such as pain and range of motion have been studied and demonstrate adequate reliability.[40-44] Several measures of functional ability, in the form of disability scales and questionnaires, have been shown to possess adequate reliability.[34,45-51] There are some differences among the various functional measurement scales in the types of functional limitations and disabilities that are assessed. Clinicians should select functional measurement scales that assess the particular functional limitations they expect to change with their treatments.

The type functional limitations that patients exhibit appear to be related to the anatomical location of existing impairments.[52] For example, patients with musculoskeletal impairments of the cervical spine may exhibit some functional limitations that are different than those exhibited by patients with impairments of the lumbar spine. Therefore, the selection of functional measurement procedures may be specific to the anatomical region being treated. A number of functional measurement scales have been developed for specific anatomical regions.[45-53]

Other considerations for selecting functional measurements include the extent to which they assess work and recreational ability, their ability to assess mental and emotional factors that may influence outcome, and their ease of application in a clinical setting. Some functional measures such as the SIP[34] are thorough in assessing work, recreational, and psychological factors, but they have been criticized for being too lengthy and time consuming for clinical use.[47] Modifications have been made on some of these procedures to make them easier to use without sacrificing the accuracy of obtained information.[35,47]

Appropriate outcome measures serve a number of uses. They may allow clinicians to categorize patients based on the severity of the clinical problem, which may guide the selection of treatment. They allow clinicians to establish measurable criteria for modifying or terminating treatment. They help to describe the extent to which our treatments affect existing impairments, functional limitations, and disability. Careful consideration should be given to selecting appropriate outcome measures for determining the effectiveness of manual therapy.

Designing Clinical Studies

Numerous factors make it difficult to design clinical studies of the effectiveness of manual therapy using traditional experimental designs. There can be a large degree of variability within patient populations. Therapists vary in their use of treatment techniques and decision-making processes for a given problem, Clinical problems are often treated with more than one manual therapy technique, and the manual techniques are usually combined with other interventions. This makes it difficult to ascertain the effects of a particular treatment technique on the clinical problem.

Manual therapy is more than the application of manual techniques. The selection of patients for treatment, decisions to change treatment, and coordinating manual therapy with other treatment interventions are all part of the process of manual therapy. Treatment effectiveness is based on successful use of this process, and this should be the focus of clinical study.

Delitto et al[54] recently investigated the effectiveness of extension exercises combined with a mobilization technique for treating patients with low back pain. This study can be used as a model to illustrate how the clinical decision-making process can be used to guide the experimental design of clinical studies on manual therapy. Delitto and colleagues' basic premise was that treatment may be more effective if patients are classified as being appropriate for a given treatment plan, based on clinical signs and symptoms.

Delitto et al[54] described specific inclusion criteria for subjects to participate in the study, based on examination results. A series of motion tests and pelvic alignment tests were used for categorizing patients. The motion tests were used to determine whether patients were appropriate for extension exercises, Subjects were classified as being improved, worse, or status quo, based on the report of pain and parasthesias during the motion tests. The categories of improved, worse, or status quo were operationally defined. Subjects were classified as being appropriate for a sacroiliac mobilization technique if they were found to have positive findings on at least three out of four tests for sacral region dysfunction. The criteria for a positive finding on each of the tests were clearly defined. The authors reported that the composite use of the four tests was found to be reliable. If subjects did not meet the criteria that would indicate treatment with extension exercises and sacroiliac mobilization, they were eliminated from the study. Therefore, subjects consisted of only those individuals who were expected to benefit from the treatment under study.

After subjects were included in the study, they were randomly assigned to either an experimental group (receiving extension exercises and mobilization) or a comparison group (receiving flexion exercises). The mobilization treatment was clearly described in terms of patient and therapist positioning, therapist hand placement, and the direction of force application. The exercises were also described. The frequency and duration of treatment were described, and treatment outcome was measured using the Oswestry Low Back Pain Disability Questionnaire.[46] Criteria for the level of disability based on the questionnaire scores were presented. Evidence for reliability and validity of the questionnaire was cited.

A number of important elements for clinical research designs were illustrated in the study by Delitto et al.[54] There was a defined set of criteria for admitting subjects into the study based on examination findings that indicate the appropriateness of treatment. This element of the research design would ensure that subjects were appropriate for the treatment under study. The treatment interventions (mobilization followed by exercise) were well described. Therapists involved in the study were limited to using the defined treatments for the duration of the study. Defining the treatments minimized variability among therapists. Treatment outcome was measured with an established measurement procedure, and criteria for improvement were based on the scores from the measurement procedure (0%-20%=minimal disability, 21%-40%=moderate disability, and so forth). These elements of the research design allow the reader to determine what the researchers considered to be an improved outcome.

As with any study, there were limitations in Delitto and collegues' research design.[54] These limitations were identified in the "Discussion" section of their report, and in the commentaries that accompanied the report.[55,56] The study, however, illustrates how clinical decision-making processes can guide the planning of clinical experimental designs. Inclusion criteria for subject participation were based on measurable impairments and functional limitations expected to change with treatment. The treatment process was clearly described. The evaluation procedures were reliable and valid. The criteria for when the authors considered patient status to be improved were based on evaluation scores.

Other Suggestions for Substantiating Manual Therapy Procedures

Based on our experience, we believe that physical therapists practicing in many clinical settings are interested in clinical research but lack the time, resources, and support to independently design and carry out large-scale experimental studies. There are. however, a number of ways in which clinicians can contribute to the body of literature.

Detailed case reports of individual patients would be an excellent way for the clinician to contribute to the literature.57 Case reports would allow therapists to describe their manual therapy techniques and their treatment decision-making process and to share their observations of the effectiveness of the treatment approaches used in their clinics. Time constraints associated with study design and data collection would not be an issue. Additional time would be needed to describe in writing the treatment, why the treatment was performed, and the outcome of treatment.

A number of factors should be addressed in the case report. A theoretical basis for selecting the treatments for the particular patient should be described. Treatment techniques and the progression of treatment should be thoroughly described. Criteria for altering treatment should be operationally defined. Reliable and valid measures of physical impairments and functional status for evaluation of treatment effectiveness should be reported. The criteria for determining whether treatment goals have been met should also be described. Case reports would seem to be a practical and convenient way for clinicians to share information and knowledge and contribute to the literature on manual therapy,

Clinicians may want to perform experimental studies to assess the effectiveness of their treatments. Some clinicians, however, lack adequate numbers of subjects required for traditional experimental research designs. Single-subject experimental designs may be an option for these clinicians.[58,59] Unlike a case report in which the subject's characteristics and response to treatment are simply described, the single-subject experimental design requires some manipulation of the treatment intervention (ie, introduction, withdrawal, or variation of the treatment).[60] The subject's impairments and functional status, as well as the manual therapy technique and clinical decision-making process, would be described in detail. Baseline measurements of the dependent variables (impairments, functional status) would be established, and the treatment would then be applied. Changes in the dependent variables would be assessed over the course of treatment. The results of studies using this type of design need to be interpreted with caution due to the small sample size. There are, however, a number of variations of single-subject experimental designs that may be used to strengthen the conclusions from these studies. For detailed descriptions of the use of single-subject experimental designs in physical therapy research, the reader is referred to Ottenbacher[60] and Payton.[61]

Clinicians could also become involved in research activities by making their facilities available to researchers for data collection and by participating in the data-collection process. Clinical research projects are often delayed due to the lack of subjects or treatment facilities. If researchers could gain access to several facilities in their community, the quality of clinical research that resulted from these projects would likely be enhanced. We encourage clinicians interested in becoming involved in research activities to contact academic institutions and discuss their interests with faculty members.

Summary

We believe that there is a need for continued investigation of the effectiveness of manual therapy. issues that should be considered when determining treatment outcome have been discussed. Operationally defining subject inclusion criteria, treatment techniques, criteria for altering treatment, and criteria for determining whether treatment goals have been achieved may help to reduce some of the variability that is inherent in clinical studies. Selecting outcome measures based on impairments, functional limitations, and disabilities that are expected to change with treatment would enhance the quality of manual therapy research. Case reports, single-subject experimental designs, and making clinics accessible for research are alternative ways for clinicians to contribute to the manual therapy literature. We hope that this discussion will stimulate continued efforts in the study of the treatment effectiveness of manual therapy.

References

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GK Fitzgerald, PT, OCS, is Assistant Professor, Department of Orthopedic Surgery and Rehabilitatio Hahnemann University, MS 502, Broad and Vine Sts, Philadelphia, PA 19102 (USA). Address correspondence to Mr Fitzgerald.

PW McClure, PT, OCS, is Assistant Professor, Department of Orthopedic Surgery and Rehabilitation, Hahnemann University.

P Beattie, PhD, PT, OCS, is Assistant Professor, Department of Physical Therapy, Ithaca College, 3 E River Rd, Ste 1-102, Rochester, NY 14623.

DL Riddle, PT, is Associate Professor, Department of Physical Therapy, School of Allied Health Pro Medical College of Virginia, Virginia Commonwealth University, PO Box 224, MCV Station, Richmond, VA 23298.

This paper was developed in part from the Manual Therapy Roundtable presented by the authors at the Combined Sections Meeting of the American Physical Therapy Association; San Francisco, CA; February 9, 1992.

This article was submitted August 14, 1992, and was accepted September 7, 1993.