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

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

Disclosures
In This Article

Materials and Methods

From March 2001 to February 2002, a total of 102 patients who referred to our outpatient orthopaedic clinic, and who consented to participate in the study, were enrolled. Participants eligible for this study were those with a newly confirmed diagnosis of subacromial impingement syndrome. Diagnosis was performed on the basis of positive Neer's[1] and Hawkins and Abrams'[12] signs as well as Neer's impingement test (injection of 10 cc of 1% lidocaine lateral to the anterior edge of the acromion and looking for reduction in pain severity). For each participant, a series of radiographs was done and included anteroposterior, true lateral, supraspinatous outlet, and axillary views of the affected shoulder.

This study was approved by the ethics committee of our institutional review board. Patients with a history of any of the following were excluded: fracture in the proximal part of the humerus, frozen shoulder, cervical radiculopathy, and long-lasting diabetes mellitus. Exclusion criteria also included the presence of radiographic signs of glenohumeral or acromioclavicular arthritis. A total of 177 consecutive patients were evaluated for inclusion of whom 49 did not meet the inclusion criteria. Thirty-five patients did not agree to sign the informed consent. This yielded a participation rate of 79%. There was no significant difference between the Constant scores of these patients and the participants (results not shown).

For each participant, a detailed questionnaire about his/her demographic factors and medical history was completed by a trained interviewer. A thorough physical examination was performed by 1 physician. Participants then entered the 12-month treatment program under a particular treatment protocol, which included an oral nonsteroidal anti-inflammatory drug (indomethacin, 75 mg 3 times daily) and (if needed) local corticosteroid injections (in which a maximum of 2 injections was allowed). After the pain was under control and the participants were able to tolerate the exercise, a detailed physical therapy program was initiated under the supervision of a specialist and continued for the rest of the follow-up period.

Follow-up visits were performed bimonthly. At each visit, a questionnaire was completed about any adverse events, participants' adherence to drug therapy, and any subjective report of pain alleviation or aggravation. Patients were given a daily physical treatment program and were asked to log their activities and drug usage. Participants were reminded of visits by telephone calls. The Constant scores[13] were calculated for the first and the last follow-up visits.

Correlations of 8 baseline variables (age, sex, pretreatment Constant score, duration of symptoms, active range of motion, involvement of dominant or nondominant side, acromial morphology, and the presence of acromial spur) to the final Constant score were evaluated. A multivariate linear regression model was used to determine the independent effects of variables on clinical outcome. With the use of a linear model, we avoided categorizing treatment results on the basis of arbitrary cut-off values. To evaluate the fitness of the multivariate model, each significant variable was entered into a univariate model; coefficients of determination (adjusted R -square) and the standard error of the estimates were compared.

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