Rationale For The Differentialdirected Approach

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One of the early skills taught to medical students is how to perform a history and physical examination. It forms the structure and base of the clinical encounter in which a diagnosis is formulated and treatment subsequently planned. Students are taught to be organized and thorough, and although much of the necessary knowledge base will come later, the structure must be stressed early and often to have a framework in which to fill in new knowledge. Traditionally, this framework follows a fairly strict order of history, physical examination, review of imaging, and the creation of a differential diagnosis. This differential is the end result of the sum total of information gained throughout the encounter. One common directive in teaching students is to not let them see any of the past notes or diagnostic conclusions during their evaluation, as such information might "tip them off" as to what to look for during the encounter, leading the student to focus on the expected findings of the examination and be too quickly directed toward the diagnosis. This is helpful for the young clinician, as it teaches completeness and avoids the pitfall of jumping to conclusions or making assumptions that the diagnosis purported by another clinician is correct. While we agree that this process is valuable to the young development of any promising diagnostician, once the framework is ingrained, the clinician will learn which findings in each specific clinical encounter are pertinent and which are superfluous. To perform every aspect of the physical examination on every patient is unrealistic, and often results in a great amount of data with no comprehension of what the data mean. It is far easier "to find what you are looking for when you know what you seek." This premise is the basis for the differential-directed approach. If one can be taught to develop a suspicion of what may be the problem(s) in the athletic shoulder at the beginning of the clinical encounter, one will stay directed, efficient, and accurate. We do not sacrifice thoroughness and completeness because other pathologic diagnoses often may not have been suspected at the beginning of the examination and may only be elucidated with appropriate physical examination maneuvers. However, we use this differential-directed approach to allow for patient-appropriate specific versus "screening" examination techniques, and we believe that the development of these initial suspicions is not only possible but is the natural history of becoming more "focused" as a diagnostician. This focus comes with experience but can be accelerated by modifying the approach to both the history and physical examination. It will become readily obvious that the success of the evaluation is directly related to the initial differential. The quality of the differential is dependent on the clinician's understanding of shoulder pathology and the various tests that are available for each. The better one's understanding is of the shoulder pathologies presented in this book, the higher the quality of the initial differential and the better the clinician becomes. This creates a dynamic relationship between knowledge and skill that can continue to improve throughout one's career. The experienced clinician learns to "go for the money" and yet not miss more subtle diagnoses.

The initial pathologic differential in the athlete's shoulder is formed from two important pieces of information: (1) the athlete's age and (2) the athlete's chief complaint. One simple example of this is the 60-year-old male tennis player with shoulder pain. Certainly the diagnosis is not guaranteed with such limited information, but the astute clinician has a working differential from the very start. Throughout the examination, the clinician has certain findings that he or she is expecting may be positive. In this example, impingement signs with associated weakness with supraspinatus testing would strongly suggest a rotator cuff tear. At the same time, features of the examination that focus on subtle glenohumeral instability might be less emphasized. This format emphasizes attention to a set of expected findings and makes the diagnosis that much more specific.

The first step in the differential-directed approach is to understand how pathologies present as chief complaints, so that the initial differential is complete but focused. It should be noted that this is rarely as easy as the example given. This is clearly illustrated if we substitute a 20-year-old baseball pitcher with pain into the example. Rather than suspecting just a rotator cuff tear, the initial diagnosis might include instability, labral pathology, impingement, internal impingement, or a combination of these. Thus, a deeper understanding of the chief complaint and how it relates to the history is necessary to come to an accurate differential. Even in difficult presentations, we still formulate an initial differential that may "tip us off" to what we are looking for while keeping us directed toward the appropriate diagnosis.

Once this differential is formulated, the remainder of the history proceeds in an organized fashion with expectations already in mind. If the differential is correct, answers to queries within the history will serve to validate the initial diagnosis. If, however, the answers given by the athlete are not what were expected, the clinician will be alerted very early to suspect another diagnosis and thus take the examination in a different direction. By the completion of the history, the clinician should have clear expectations of what to look for and emphasize in the physical examination.

It would be ideal if we could exactly reproduce an athlete's symptoms during the physical examination, but this is only occasionally possible. Many tests for pain are not specific enough to be reliable, and patients with instability are often too guarded to allow provocative testing. In the throwing and overhead athletic population, many pathologies coexist and make presentations confusing. It is therefore important that the physical

Figure 16-1 Neer impingement test: Instillation of local anesthetic into the subacromial space alleviates the previous pain that was demonstrated with the Neer impingement sign, indicating the pathology of subacromial impingement.

examination remain organized and systematic. One of the dangers of having a short list of differential diagnoses in mind is that the clinician's attempts to be focused could result in an examination that is incomplete. Although we recommend reorganizing the examination according to the differential, the essential tenets of "inspect, palpate, and move" the shoulder remain.5,6

Diagnostic injections can be very helpful in determining the source of symptoms. The goal is to eliminate the athlete's clinical signs and physical symptoms with the use of a short-acting local anesthetic placed in the specific anatomic area that seems to be responsible for the symptoms. This maneuver is the equivalent of the Neer subacromial "impingement test" (Fig. 16-1) and can be applied to a variety of other conditions in the differential diagnoses. There are limitations to this, as differential injections are time-consuming and often are not applicable for diagnoses such as instability. When pain is the presenting complaint, a diagnostic injection in a specific location that quickly (within 5 to 10 minutes) takes away nearly 100% of the athlete's pain often leads to the area of pathology and the correct diagnosis.

The organization of this chapter is according to chief complaint, followed by the specific historical questions and physical examination maneuvers that are applicable to each entity. This is an alternative approach from traditional texts where it is more common to separate the history from the physical examination and from diagnostic injections. Nevertheless, we believe that this organization more closely resembles how we approach the evaluation of the athlete's shoulder.

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