Sunday, December 14, 2014

What happens to the rotator cuff after a cortisone injection?

Incidence of full-thickness rotator cuff tear after subacromial corticosteroid injection: a 12-week prospective study.

These authors carried out a prospective study of 102 patients with chronic shoulder pain. Initial ultrasound revealed that 49 had full thickness rotator cuff tears - these patients were excluded from further study.

Of the remaining 53, 39 had supraspinatus tendinopathy (24 with partial thickness tears (19 bursal side and 5 intrasubstance)). 11 had bursitis and 3 had a joint effusion. 19 patients were male, average age 61 years, average duration of symptoms 10 months, active flexion 147 degrees.

All 53 patients received a subacromial injection of 40 mg. of triamcinolone acetone. Patients did not receive rehabilitation therapy. 

At 12 weeks ultrasound was repeated. 9 patients were found to have new full thickness cuff tears. 6 of the 24 patients identified has having had a partial thickness cuff tear at the initial evaluation progressed to a full thickness tear at 12 weeks after injection.  3 of the 29 patients without an initial partial thickness tear had a full thickness tear at 12 weeks after injection.

7 of the nine patients with new full thickness cuff tears had improved symptoms, the two that did not improve had larger sized tears.
31 of the 44 patients not developing full thickness cuff tears had improved symptoms.

In all  50 of the 53 patients recovered a normal range of motion. Symptoms were improved in 38.

The authors also had 7 patients in a "control group" in which cortisone was felt to be contraindicated (allergy, poorly controlled diabetes). All seven had supraspinatus tendinopathy, 3 had partial thickness tears. These shoulders received an injection of local anesthetic only. At 12 weeks there were no full thickness tears. All 7 had improved motion and 6 had improved symptoms.

Comment:  This study is of interest in that it revealed a very high incidence of rotator cuff pathology in chronically symptomatic shoulders, including almost half with full thickness tears. 

The authors conclude "Corticosteroid injection is highly effective in improving clinical symptoms of rotator cuff tendinopathy at 12 weeks." We are not sure this is what the data reveal - the results in the 'control' group of 7 shoulders (in which corticoids could not be given) were at least as good as those receiving triamcinolone. This would have been a more informative study if the patients had been randomized to receive either triamcinolone or local anesthetic alone. Without these data we cannot learn the role of the triamcinolone in tear progression or in symptom improvement.

Here's our attempt at a graphical presentation of their data

Thus from this study we cannot conclude that steroid injections are more effective than local anesthetic in improving symptoms. Nor can we come to conclusions about the possible role of steroid injections in the progression of cuff tears - although there were no new full thickness tears in the 'control' group, the numbers are too small to make a robust conclusion.

It is apparent that the authors have a robust methodology and are ideally positioned to answer questions such as
(1) in an randomized controlled study, are steroid injections are more effective than local anesthetic injections in improving range of motion and symptoms?
(2) in an randomized controlled study, are steroid injections are more likely than local anesthetic injections to be associated with tear progression?

Finally, this study reminds us that the symptoms experienced by a patient with a cuff tear may arise from a wide variety of causes, including (1) tension at the margin of the tear (as in tennis elbow), 

(2) subacromial abrasion of a prominent tuberosity or hypertrophic bursa, 

(3) weakness, (4) instability (5) stiffness or (6) cuff tear arthropathy. It is important to sort out the origin of the symptoms before launching a treatment program. For example, if the issue is limited range of motion a gentle rehabilitation program may be preferable to an injection or surgery.


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