Outcome Predictors in Nonoperative Management of Newly Diagnosed Subacromial Impingement Syndrome: A Longitudinal Study

Afshin TaheriAzam, MD; Mohsen Sadatsafavi, MD; Alireza Moayyeri, MD

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In This Article

Discussion

We found that the predictive value of the pretreatment Constant score could be empowered by taking into account the effects of acromion morphology and pretreatment symptom duration. This is quantitatively shown by better fitness of the 3-variable model than the univariate models.

Diagnosis of subacromial impingement syndrome in our study was based on the classic Neer's[1] sign and impingement test. Preferred reference tests for assessment of the shoulder in soft-tissue disorders are arthroscopy and surgery,[14] which are not applicable in a conservative management setting as was used in this study. Neer's test has been estimated to have a high sensitivity and a relatively low specificity.[14] However, our exclusion criteria seemed to refine this specificity, because it is likely to exclude patients with other diagnostic labels, such as adhesive capsulitis and glenohumeral osteoarthritis. Other diagnostic tests, such as ultrasonography and magnetic resonance imaging (MRI), are unlikely to be superior to Neer's test in diagnosis of the impingement syndrome.[14]

Conservative therapy used in different studies consists of several modalities, including oral nonsteroidal anti-inflammatory drugs, intra-articular and subacromial glucocorticoid injections, oral glucocorticoid treatment, physiotherapy, and hydrodilation.[4,15,16,17,18] Many investigators who have reported on nonoperative treatment of subacromial impingement syndrome have documented successful results, especially when patients were managed in the early stages of the disease.[19,20,21] However, systematic reviews have revealed inconclusive evidence for the real efficacy of such therapies.[3,5,6]

In a retrospective study assessing the outcome of conservative treatment on 616 patients,[22] a favorable outcome was observed for patients between 41 and 60 years old, whereas Bartolozzi and associates[19] in another retrospective study found no difference in outcome among the different age groups. We also did not find any remarkable correlation between age and patients' outcome. In another prospective study,[21] type I (flat) acromion was associated with better outcome with conservative management, whereas patients with type III (hooked) acromion had the worst response. Our findings are in accordance with this study. In one study,[19] the duration of symptoms for more than 1 year was found to be related with unfavorable outcome, whereas in another study,[23] a cut-off of 6 months for the duration of burden showed no significant difference between outcomes of conservative treatment in the 2 groups. Our study, however, showed a significant predictive value for this variable.

The prospective design of this study allowed us to minimize several potential biases and apply a unique diagnostic approach and therapeutic program to all patients. However, our study had some limitations. First, we did not evaluate the correlation between the extension of rotator cuff pathology and patient outcome because we didn't perform MRI or ultrasonography tests for all participants. Rotator cuff pathology has been found to have a predictive value on final outcome,[19] although in practical settings, it is not feasible to perform these tests on all patients, particularly those with good initial conditions. Second, although the Constant scoring system is widely used and its method is clearly described,[13] it has been criticized for its relatively low reliability and for being highly dependent on range of motion and muscle strength, while ignoring important factors, such as patient quality of life.[24,25]

This study did not attempt to compare the results of conservative treatment with other treatment modalities. Furthermore, considering current opinion on the usefulness of conservative therapies as the first line of treatment[4,16,18] and regarding ethical issues on performing invasive procedures on this population, we did not recruit a matched control group treated with surgical procedures; therefore, these results cannot be weighed against surgical-intervention reports.

Conservative therapy could be a valuable option in patients with subacromial impingement syndrome. Severity of pretreatment conditions does not necessitate a more invasive therapy. Predictive power of initial functional impairment could be refined if one considers the duration of symptoms and acromial morphology. In patients with such poor prognostic factors, it seems better to choose aggressive therapeutic methods as the first-line intervention. However, further investigations with larger sample sizes, longer follow-up periods, and with the use of modern, validated-function assessment tools are needed to develop a precise decision guideline for choosing the appropriate treatment method for patients.

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