Classification of Shoulder Pain

Original Editor - Naomi O'Reilly

Top Contributors - Naomi O'Reilly, Lauren Lopez, Rachael Lowe, Fasuba Ayobami and Claire Knott  

Introduction

Classification provides a general framework for identifying subgroups of patients based on the primary goal of treatment, with the ultimate aim of matching indivuals to specific interventions from which they are most likely to benefit [1]. Diagnostic algorithms and classification may be beneficial to clinical decision making and allows clinicians to easily identify the correct intervention strategy, guide treatment decision making and inform a patient’s prognosis. Additionally communication among health care providers, researchers, and those utilizing research findings is possible through the use of diagnostic categories.[2]

Evidence for the conservative management of shoulder pain currently does not support any particular approach. There has been a shift from the pathoanatomical model of diagnosis towards treatment or rehabilitation-oriented classification that will inform patient management.[2] This form of classification provides a general framework for identifying subgroups of patients based on the primary goal of treatment, with the ultimate aim of matching individuals to specific interventions from which they are most likely to benefit, which can change as they progress through the different stages of treatment.[2]

Classification Types

Pathoanatomic Model

Definition of shoulder conditions and the nomenclature used to describe them is extremely varied, and as a result there have been many attempts at standardizing the use of diagnostic labels utilising classication systems. Traditionally these classification systems or diagnostic categories such as those pro­posed by Waris et al.[3], Cyriax [4], Neer [5], Viikari­Juntura [6], Silverstein [7], McCormack et al. [8], Uhthoff & Sarkar [9], ICD­10 [10] and Palmer et al. [11] were all based on a pathoanatomic medical model aimed at identifying the pathologic tissues which was responsible for the shoulder pain[12]. The pathoanatomical model looks to explain the source of the patients presenting signs and symp­toms based on the presence of specific structural pathology identified through isolated or combined physical examination, imaging and histo­pathological analysis.[12]

Diagnostic labels based on tissue-specific pathology fail to accurately classify the patient into subgroups for clinical decision-making and many of these classification systems based on the pathoanatomic model for shoulder pain have been shown to be unreliable resulting in a lack of diagnostic consistency in relation to shoulder pain. [13] Recent research suggests that the pathoanatomic model may not provide a classification systems or diagnostic categories that effectively guide treatment decision making in rehabilitation management of shoulder pain.[2]

Shoulder disorders, classified through a pathoanatomic diagnosis infer that patients with the same tissue pathology form a homogeneous group which guide decisions for treatment and prognosis.[2][12] This form of classification suggests that patients with the same pathology should be managed in the same way, have similar prognoses and that the diagnosis remains static throughout the whole period of their care. It is also suggested that it is this pathology which explains both the symptoms and impairments (activity limitations and participation restrictions) experienced by the patient and that correcting the pathology will improve the symptoms and impairments.[2][15] The pathoanatomic diagnosis may be inadequate for guiding rehabilitation as the categories encompass patients with similar tissue pathology, but within each pathoanatomic category, there often exists a heterogeneous group of patients with different or varying degrees of impairment and pain that require a different rehabilitation approach rather than managed in the same way.

The International Classification of Diseases and Related Health Problems (ICD-10) provides the following examples of Pathoanatomic Diagnostic Labels for Shoulder Pain; [10]

  • M75.0 Adhesive Capsulitis of the Shoulder (Frozen Shoulder, Periarthritis of the Shoulder)
  • M75.1 Rotator Cuff Syndrome (Rotator Cuff or Supraspinatus Tear or Rupture (Complete or Incomplete) not specified as Traumatic, Supraspinatus Syndrome)
  • M75.2 Bicipital Tendinitis
  • M75.3 Calcific Tendinitis of Shoulder, Calcified Bursa of the Shoulder
  • M75.4 Impingement Syndrome of the Shoulder
  • M75.5 Bursitis of Shoulder
  • M75.8 other Shoulder Lesions

Treatment Based / Rehabilitation Model

Recent evidence suggests a poor relationship between diagnostic pathoanatomic classification and chosen rehabilitation interventions among orthopedic physical therapists and as such this suggests that clinical decision making based on a clinical diagnosis and use of diagnostic labels arrived at using special orthopaedic tests is flawed.[2][12] In line with the difficulty in deriving a definitive structural diagnosis from clinical tests and imaging, current researchers have suggested to base physiotherapy treatment decisions on physical assessment findings and not structural pathology with development of classification models based on treatment and rehabilitation including Hughes et al. [16], Schellingerhout et al. [15], Lewis [17], Lewis et al [18], May [19], Klintberg et al [20], Mc Clure and Michener [2] and Ludewig et al [21].

One such model, the Shoulder Symptom Modification Procedure, examines the influence of thoracic posture, scapular posture and humeral head position on shoulder symptoms through a systematic process with additional screening of both the cervical and thoracic spinal regions to determine their influence on symptoms, if any. In the first stage of the process is to identify relevant aggravating movements, activities, or postures that reproduce symptoms and then through a systematic approach a step-wise algorithm is applied to these aggravating movements, activities, or postures to determine if the symptoms are altered and to what extent. Where a component or combination are found to alleviate or reduce symptoms of shoulder pain or dysfunction then this informs the clinical management and forms part of the treatment - hence why known as a Treatment Based Model. The Treatment Based Model, in this case the SSMP, cannot determine if the changes in symptoms produced during the assessment process are the primary cause of the patient’s presenting symptoms.[17][18]
The Shoulder Symptom Modification Procedure (SSMP), described by Jeremy Lewis [22][23], is a logical approach to the assessment of patients with rotator cuff and subacromial pathology. It is also a very useful guide to clinical decision making and determining those patients which will respond well to the correct rehabilitative programme.

As with the Pathoanatomic Model of Shoulder Classification further research is required to determine reliability, validity, and prognostic value of procedures such as those used with the SSMP but meanwhile Treatment Based Models bridge the gap in knowledge in current clinical practice until more robust clinical diagnostic methods and imaging identifying the location and cause of symptoms become available.[18]

Movement System Model

Ludewig et al [21] advocate for the development of a kinesiopathological model or movement system classification, which would create a diagnostic classification based on characteristic movement impairments that potentially are the cause of, or consequence of, the individuals pain or dysfunction. This model of classification provides a direct link to the intervention approach required to treat the specific movement impairment. [21]

While this model does recognise that pathoanatomy plays a role in clinical-decision making, and does not preclude specific tissue pathology, it treats the pathoanatomical diagnosis as a modifier rather than the overarching classification. It also recognises psychosocial components and the role it plays in shoulder pain. It is the assimilation of all the collective findings including the pathoanatomy through clinical reasoning and judgement which assist in determining which is most representative of the individuals’s movement system dysfunction or impairment.[21]

As with any classification model, the movement system framework is not without limitations and require further research to determine reliability, validity, and categorisations within the movement system framework. Similarly, to support this is the need for the development or selection of associated clinical diagnostic tests and measures which assist in the classification process. [21]

Clear communication between health care professionals is key for best practice and patient care and in line with this further discussion is required in order to determine the most appropriate labels for each of the diagnostic categories, which should be based on the following criteria endorsed by the American Physical Therapy Association (APTA) for use with a movement system diagnostic classification.[21][24]

  1. Use recognized movement-related terms to describe the condition of the movement system;
  2. Include, where necessary, the name of the pathology, disease, disorder, anatomical or physiological terms, and stage of recovery associated with the diagnosis.
  3. Be as succinct and direct as possible to improve clinical usefulness.
  4. Strive for movement system diagnoses that span all populations, health conditions, and the lifespan. Whenever possible, use similar movement-related terms to describe similar movements, regardless of pathology or other characteristics of the patient. [21][24]
The Movement System Model provides a direct flow from movement diagnosis, to assessment of movement impairments, to targeted intervention which can aid in the development and advancement of clinical expertise through more efficient and targeted learning.
Proposed classification of primary patterns of movement impairments. Clients may present with shoulder pain of non-mechanical or non-shoulder origin, requiring alternate classification. Within those with symptoms or dysfunction of mechan- ical origin, glenohumeral or scapulothoracic subtypes are distinguished. Further specificity is provided for the scapulothoracic subtypes. It is recognized that multiple movement impairments may be present and the classification is based on the movement impairment pattern believed most relevant to the client’s presentation. [25]
Additional classification of potential movement impairment contributors to a condition, and subsequent targeted treat- ment approaches that may follow.[26]

Staged Approach for Rehabilitation Classification: Shoulder Disorders (STAR–Shoulder)

Mc Clure and Michener[2] propose a Staged Approach for Rehabilitation Classification of Shoulder Pain (STAR–Shoulder), incorporating both the pathoanatomic and treatment based models, which are derived through a detailed screening process comprising of history and physical assessment. While currently this system is only at a conceptual stage, with a need for further research to evaluate, refine, and validate the proposed model, it shows the potential to be useful both clinically for guiding rehabilitation intervention, and in possible future research studies in order to identify relevant subgroups for future research studies.[2] The STAR-Shoulder incorporates the following elements;

1. Screening

Incorporates the history and basic physical assessment in order to gain a overall impression of the problem and identify potential “red flags” and “yellow flags”, to determine if the are signs and symptoms are consistent with a musculoskeletal problem amenable to rehabilitation rather than a more serious disorder requiring onward referral

2. Pathoanatomic Diagnosis

Derived from a combination of history, special orthopaedic tests, and results of imaging where available, the pathoanatomic diagnosis as we discussed above is made based on identifying the presumed tissue pathology generating the signs and symptoms. Often it is at this stage where primary intervention decisions such as surgery versus conservative treatment, which may include medication, corticosteroid injection, rest, and rehabilitation are determined.[14]

3. Rehabilitation Classification

Rehabilitation sub categories are are developed based on the different stages of tissue irritability, which then guide the intensity of treatment, with impairments utilised to guide selection of specific rehabilitation techniques. The concept of tissue “irritability” reflects the ability of the tissue to handle physical stress which in theory relates to its overall physical status and degree of inflammatory activity present in the tissue. 

Overall system for classification incorporating screening, pathoanatomic diagnosis, and rehabilitation classification. The specific pathoanatomic diagnoses shown at level 2 are only given as common examples; these are not meant to represent a complete list. For clarity, pathoanatomic diagnosis and rehabilitation classification are listed sequentially. However, they both are derived primarily from the history and physical examination and, in practice, likely occur in parallel rather than sequentially. [27]

Conclusion

Comparison of Features between Pathoanatomic and Treatment / Rehabilitation Based Classification [28]

As we have examined above specific pathoantomic diagnosis and classification can be difficult as a result of inconsistent relationships between tissue pathology and impairments which limit the lone use of pathology for clinical decision making. The pathoanatomic diagnosis alone cannot fully direct the intensity and specific intervention tactics used in the treatment of patients with musculoskeletal shoulder disorders. Previously physical assessment of the shoulder was based on the premise that orthopedic tests, which apply compression, stretch or isolated contraction to selected tissues, allow isolation of specific anatomical structures. [12] The difficulties associated with generating a relevant structurally specific diagnosis relating to the shoulder are evident and now consistently reported across a wide body of literature. Current research suggests that these orthopaedic special tests are unlikely to selectively isolate an individual tissue from adjacent structures, making it difficult to determine which structures are involved in the patient’s symptoms and as such these tests have limited reliability, only moderate diagnostic validity at best.[12][29] Additional challenges exist within this pathoanatomic diagnostic framework including the issues that many of the specific pathoanatomical findings co-exist, and many shoulder pathologies present with similar examination findings, but these diagnostic labels have limited ability to direct selection of interventions.[21][30]

Given the difficulty to accurately diagnose shoulder pain based on pathology alone, there have been ongoing debate on the need to change our approach from pathoanatomic diagnosis towards a more treatment or rehabilitation focussed approach based more on prognositic factors.[31] An important point of consideration in this from a Physiotherapy perspective is that as physiotherapists we focus on movement-related impairments rather than structural anatomy as we are unable to influence the shape of the acromion, remove acromial spurs or restore the integrity of the labrum. More specifically physiotherapists try to influence motor control, soft tissue strength, flexibility, functional osteokinematics and arthrokinematics and as such our treatment strategies are grounded more on the identified impairments, tissue irritability and patient-related goals and expectations. Considering the fact that impairments in the shoulder are often related to abnormal scapulothoracic or gleno-humeral kinematics, muscle performance deficits or kinetic chain dysfunctions, the challenge will be to identify impairment patterns to classify patients based on movement dysfunction instead of pathoanatomic diagnoses, and to establish reliability and validity of these classifications.

While the idea that a structurally specific diagnosis is needed before a successful treatment regime is implemented has been questioned[30], both Ludewig et al[21] and McClure and Michener [2] believe the pathoanatomic diagnosis is still an essential element of the process for classification of shoulder pain. As such the STAR Classification System is founded with the underlying pathoanatomic diagnosis, and then expanded to aid rehabilitation treatment decision making by classifying the level of irritability and identification of impairments.[2]  

Future classification of shoulder pain should consider both pathoanatomical diagnosis, the different stages of tissue irritability and the relevant impairments such as movement to drive treatment clinical decision-making. Classifying patients into subcategories will help the clinician to determine the treatment strategy, recognising that over the course of an episode of care, patients may shift from one category to another, or be considered appropriate for two categories at the same time.

As mentioned earlier, clear communication between healthcare professionals is paramount for the development of any classification system, and as such the need for standardised diagnostic labels across the range of shoulder pain is key to facilitate and enhance consistent communication between healthcare professionals and patients for best patient care and will pay a huge role in the development of consensus in the classification of shoulder pain. [2][17][21]

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