A model of orthopaedic dysfunction for clinical decision making in physical therapy practice.

A Model of Orthopaedic Dysfunction for Clinical Decision Making in Physical Therapy Practice This Article describes a model of orthopaedic dysfunction that we use as a framework for our advanced master's degree orthpaedic and sports curriculum at the MGH Institute of Health Professions. [1] This model is offered as an alternative to the traditional medical model that focuses on the etiology, diagnosis, and treatment of disease. The purpose of the model of orthopaedic dysfunction is to provide a hypothetical rationale to explain the cause and effects of soft tissue dysfunction. [1] The purpose of this article is to present the model of orthopaedic dysfunction as a clinical decision-making tool. The model can be used to analyze the etiology of dysfunction, which may contribute to the development of a body of knowledge relevant to the profession of physical therapy.

This model of orthopaedic dysfunction was developed because we believe a key quality of the clinician is to demonstrate clinical judgment substantiated by current theory and science. Clinicians should be able to explain why they chose a particular examination or treatment action or interpreted signs and symptons in a certain manner in terms of the patho-physiology of the dysfunction.

The model is offered as a guideline for therapists to formulate and compare hypotheses of dysfunction. Understanding the etiology of dysfunction is essential in clinical decision making prior to establishing the prognosis, duration, and frequency of treatment. We recognize that there are other contributing variables, such as the psychological, social, and functional needs of a patient, which strongly influence treatment strategies. The purpose of this model, however, is to present a unifying framework of pathophysiological and pathokinesiological processes to theoretically illustrate the development of orthpaedic dysfunction and its effects. The model of orthopaedic dysfunction is based on the static and dynamic properties and function of the neuromusculoskeletal tissues and structures. [2-11] The altered properties of those tissues are related to the etiology of pain, impairment, and disability.

This article will review the essential components of the model and, using the case method, explain below how it may be used to analyze examination and treatment strategies. We will also discuss how the content of the model is applicable to clinical practice, education, and research.

Review of the Model of

Orthopaedic Dysfunction

The model expands on the classical concept of a stimulus causing a response (Fig. 1). Figure 2 emphasizes the stimuli and subsequent internal tissue responses that hypothetically result in orthopaedic dysfunction. Although all sections of the Figure could be expanded, we have chosen to diagram the internal tissue response section in the most detail to allow clinicians to analyze the patient's impairements and disabilities in terms of the pathophysiology of the dysfunction. Although a particular chain of events will not apply to all patients, the sequence depicted in Figure 1 is applicable in most clinical situations.

The terminology chosen for the last three category headings of the model and their definitions are derived from the World Health Organization's International Classification of impairments, Disabilities, and Handicaps. [12] Impairments refer to the abnormalities of anatomic, physiologic, or psychologic origins within specific organs or systems of the body. Physical therapists tend to evaluate or measure impairments (eg, decreased range of motion, limited muscle performance). Functional disability refers to a restriction or inability to perform a normal range of activities of daily living. The World health Organization has classified functional disability into four categories: 1) physical, 2) mental, 3) social, and 4) emotional. Examples of physical disabilities we deal with as physical therapists are limitations in performing ADL skills such as transfers and gait and higher level skills such as athletic activities. Handicap describes limitations in the fulfillment of an individual's normal role, depending on age, sex, and other social and cultural factors. An example of a handicap is inability to perform one's occupation.

In keeping with this terminology, therefore, it can be said that specific impairments contribute to an individual's functional disability. After careful examination and the formulation of an assessment, an important aspect of clinical decision making is to select the correct therapeutic action for the patient. This treatment must be based on the individual's needs but must also be related to the etiology of the patient's dysfunction. Physical therapists traditionally evaluate and measure those limitations identified in the impairment section of the model. Subsequently, treatment interventions may be limited to only addressing the impairment. Perhaps this intermediate level is assessment and treatment is fostered by the patient's tendency to describe their own problems in terms of pain and functional disability. By reviewing the chain of events diagrammed in the internal tissue response section of the model according to the patien's mechanism of injury, however, the therapist can formulate a hypothesis of dysfunction. By identifying what phase of reaction the involved tissues are in, the therapist can propose more sensitive treatment techniques based on the altered tissue properties. For example, if a patient has limited knee flexion and extension secondary to an acute inflammatory process, the treatment strategy should be targeted at reducing the inflammation, improving tissue nutrition, and preventing the sequela of the inflammatory response such as fibrous reaction of the contractile tissue. By using finer examination techniques and integrating the information with the pathological condition, the clinician will have a clearer supporting rationale for the treatment.

From this model, generic treatment goals were developed according to the sequence outlined in the internal tissue response section progressing through the impairments and functional disability levels (Appendix 1). These goals are based on the events documented in the internal tissue response section, and interventions are determined by whether certain responses have taken place or need to be prevented.

Applications of the Model

This section will use a case study to illustrate how to apply the model in a clinical situation. After reading the history and subsequent examination findings of this case study, formulate a provisional patient assessment.

Case Study

"GW" is a right-handed, 53-year-old man who was referred to physical therapy for examination and treatment of a painful, stiff right shoulder.

History of present problem. Three months ago, GW was lifting his 25-hp outboard engine out of the water when he felt a sudden sharp "pop" over the anterior portion of his shoulder followed by burning pain over the lateral aspect of his proximal arm. He reports thast his symptoms gradually subsided over the next week, although he continued to have pain on any attempt to do overhead activities. He stopped playing tennis and exercising at the health club. During the past two months, he notice that he seemed to be "getting stiffer" and was having difficulty working. GW also complained of difficulty sleeping because he was unable to lie on his painful right shoulder.

One month ago he consulted with an orthopaedic surgeon who began a work-up. Radiographs showed some glenohumeral joint-space narrowing and a mild joint effusion. There was no evidence of calcification. The physician suggested that he begin taking a nonsteroidal anti-inflammatory drug (Feldine [R] (*)) and start physical therapy.

GW past medical history is noncontributory. He is a dentist who lives with his wife and three teenage children. GW's initial physical therapy evaluation is presented in Appendix 2 and the Table.

Application of model to results of patient examination. By referring to Figure 2, we can identify that the initial stimulus was physical trauma; for discussion purposes, we can hypothesize it caused immediate tissue insufficiency of the rotator cuff, which created altered internal tissue stress. Stress refers to the magnitude of internal load in a structure or a tissue. A closer look at the internal tissue response section allows the chain reaction, which can occur from the tissue insufficiency, pain, and subsequent inflammatory responses, to be identified. We then follow down through the left side of the internal tissue response section and identify a result of the inflammatory process on the noncontractile tissues involved (ie, the fibrous reaction resulting in soft tissue contracture). A subsequent progression of the contracture is dysfunction of the articular structures. The contracture and articular dysfunction each contribute to altered internal tissue stress. This stress can be manifested as premature or latent loading of tissue, excessive or reduced magnitude of load, or altered site of tissue load. For example, the resultant abnormal loading of tissue can result in pain from excessive stimulation of articular neuroreceptors and chronic inflammatory reactions, altered proprioception, and myoarthrokinetic reflexes.

The above discussion is one example of how the data gathered during an examination can be related to the internal tissue response section of the model to hypothesize why the patient exhibits specific impairments. In this patient, for example, joint mobility at three months postinjury is limited in a capsular pattern. We know that there is marked supraspinatus muscle tenderness and joint tenderness at the rotator cuff insertion. There is also general muscle wasting. By relating these findings to the internal tissue response section of the model, the student can then logically map out the sequence of pathophysiological events and identify appropriate treatment strategies aimed at the tissue dysfunction of the impairment.

In summary, from the case example, some objectives of this model for clinical practice are 1) to provide a framework for clinical decision making based on the physiological and mechanical sequelae of soft tissue dysfunction and 2) to identify a rationale for the etiology and management of pain and dysfunction.

Implications for Education

and Research

The model is also applicable in the educational setting. The main objective is to establish a framework for the critical analysis of clinical practice concepts in orthopaedic physical therapy and other disciplines. The assessment by the physical therapist may be analyzed to determine whether the specific etiology or the patient's impairment has been identified or whether the assessment is merely a restatement of the impairment itself. In a similar manner, the goals and treatment plan can be evaluated for their relevance and thoroughness based on the diagnosis. Additionally, various theories and strategies of therapeutic intervention, from within and from outside the physical therapy profession, can be compared for their relative strengths and weakness.

The model is used at the MGH Institute of Health Professions (Boston, Mass) as a framework for teaching students how to make clinical judgments that can be substantiated by clinical theory, practice customs, and science. We have developed a core course teaching these basic concepts using analysis of case studies for practice. The content areas are divided into topics identified in the internal tissue response section of the model and include lectures and discussion examining clinical implications of inflammation, pathokinesiology of joint and soft tissue contracture and instability, mechanical behavior of connective tissue, muscle structure and function, and analysis of generic treatment strategies. Dysfunction of contractile and noncontractile soft tissues and articulations are related to clinical examination and treatment techniques.

Examples of the study objectives generated by this model are given in Appendix 3. These types of analyses allow therapists to relate why they have chosen to apply a particular treatment strategy to the pathophysiology of the dysfunction. Furthermore, they can clearly define in the literature which strategies have been substantiated or warrant investigation.

Therefore, the model can also be used to aid the therapist in identifying research goals such as 1) to determine the role of various etiologies in the production of pain, 2) to formulate research questions investigating the manner in which manual and modality therapeutic interventions work, and 3) to compare the effectivenes of tissue-based and nontissue-based treatment strategies. The model itself is subject to analysis for confirmation. Currently, it is based on knowledge obtained from the applied science literature.

Summary

This model serves as a framework for the critical analysis of current practice concepts. The analysis obtained from using this model should be integrated with other physiological systems of the body during examination and treatment processes. Currently used as a basis for graduate study in orthopaedic physical therapy, the model helps students identify fundamental research questions, compare various examination and treatment philosophies, and comprehend generic treatment goals and strategies.

Acknowledgments

We would like to acknowedge Terry Michel, Mary Watkins, and Valerie Grande for their help in preparing this manuscript.

(*) Pfizer Laboratories Division, Pfizer Inc, 235 E 42nd St, New York, NY 10017.

B Harris, MS, PT, is Assistant Professor, Program in Physical Therapy, MGH Institute of Health Professions, 15 River St, Boston, MA 02108-3402, and Clinical Research Associate, Department of Physical Therapy, Massachusetts General Hospital, Fruit Street, Boston, MA 02114.

D Dyrek, MS, PT, is Assistant Professor, Program in Physical Therapy, MGH Institute of Health Professions, and Director, MGH Physical Therapy Associates, 60 Staniford St, Boston, MA 02114.

Address correspondence to Ms Harris at Program in Physical Therapy, MGH Institute of Health Professions, 15 River St, Boston, MA 02108-3402 (USA).

This article was presented in poster format at the Sixty-Third Annual Conference of the American Physical Therapy Association, San Antonio, TX, June 28-July 2, 1987.

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