EVIDENCE-BASED ANSWER
Subacromial steroid injection may provide a small, short-term benefit compared with placebo. The short-term effectiveness of steroid injection compared with nonsteroidal anti-inflammatory agents (NSAIDs) remains unclear.
Steroid injections are better than physiotherapy alone in the short term. However, injection does not appear to provide any meaningful long-term benefit compared with other therapies (strength of recommendation: B). Data are insufficient to make recommendations regarding the proper timing of injection in the sequence of other treatments. Side effects of steroid injection, such as steroid flare and infection, are rare.
Evidence summary
A Cochrane Review of corticosteroid injections for shoulder pain found 7 randomized controlled trials comparing subacromial steroid injections with placebo.1 The placebos were either injectable anesthetics alone or injectable anesthetics combined with oral placebo tablets. Six of the 7 studies used the anterolateral approach to inject under the acromion.
All studies used a clinical exam for diagnosis that showed pain with range of motion (especially abduction) or pain that was consistent with impingement syndrome. Most of the follow-up times were short, typically 4 to 12 weeks, and the longest study was 33 weeks. Meta-analyses often report the effect size using standard mean difference (SMD). A rule of thumb for interpretation of SMD is a value of 0.2 indicates a small effect, a value of 0.5 indicates a medium effect, and a value of 0.8 or larger indicates a large effect. If the 95% confidence interval [CI] does not include zero, then the SMD is statistically significant at the 5% level (P<.05).2
Two of the studies comparing steroid injection with placebo were methodologically suitable for meta-analysis; these studies showed thatsteroids provided a mild, short-term (4-week)benefit with respect to pain (SMD=0.83; 95% CI,0.39–1.26), function (SMD=0.63; 95% CI,0.20–1.06), and abductive range of motion(SMD=0.82; 95% CI, 0.39–1.25).3,4
Results of the remaining, less rigorous trialswere conflicting and inconclusive. The reviewersalso found 3 randomized controlled trials comparing subacromial steroid injection with oralNSAIDs. The pooled results of these trials,encompassing 120 patients, found no differences in these 3 outcomes at 4 or 6 weeks. The review of an additional trial of 50 patients comparing subacromial steroid injection plus simultaneous oral NSAIDs with oral NSAIDs alone found no differences at 4 weeks. All 11 studies had small sample sizes, and suffered from variable methodological quality and heterogeneous results.
The reviewers concluded that steroids are probably better than placebo but provide little or no benefit in addition to NSAIDs, and that evidence is insufficient to guide treatment. Likewise, a Cochrane Review of multiple interventions for shoulder pain also found “little evidence to support or refute the efficacy of common interventions” and highlighted the need for new, well-designed trials.5
Another Cochrane Review examined 4 randomized controlled trials comparing physiotherapy interventions for shoulder pain.6 They found that steroid injections may be superior to physiotherapy for rotator cuff disease, but the type of physiotherapy and injection sites were not consistent across the studies, making creation of summary estimates inappropriate. The individual studies showed significant short-term benefits (3–7 weeks) of steroid injection over physiotherapy; however, long-term (6–52 weeks) benefits ranged from some benefit to no difference. These studies were consistent regarding age (mean age=53–55 years, SD ± 13–14 years) and complications reported, with the only side effect being postinjection soreness.
Hay et al7 conducted a multicenter, primary care–based randomized controlled trial with more than 200 patients, which was published too recently for inclusion in the Cochrane Review. They found no statistical difference in improvement between steroid injection without physiotherapy and physiotherapy alone at 6 weeks.
In 1996, van der Heijden et al8 systematically reviewed randomized clinical trials of steroid injections for shoulder disorders, including rota-tor cuff disease, adhesive capsulitis, rheumatoid conditions, and periarthritis. They screened more than 200 articles from searches in Medline (1966–1995) and EMBASE (1984–1995) and found 16 articles that met qualifying conditions for further review. Of these, 3 were methodologically adequate for final review. None of these 3 studies provided evidence showing the efficacy of steroid injections. The results of the major trials reviewed can be found in the Table .
TABLE
Major placebo-controlled trials of injectable steroids for shoulder pain
| Steroid (n) | Comparison | Follow-up arms (n) | Reported results | Conclusions |
|---|---|---|---|---|
| Methylprednisolone 1% lignocaine (28) | 1% lignocaine (28) | 12wks | 2 wks:insignificant improvement in steroid arm 2, 4, 6, 12 wks:no difference in pain, range of motion;all P>.05 | No significant advantage of subacromial methyl prednisolone over lignocaine10 |
| Triamcinolone, 0.5% lignocaine, placebo tabs (20) | C1:diclofenac, lignocaine (20) C2:placebo tabs, lignocaine (20) | 4 wks | 4 wks:steroid and C1 showed significant benefit over C2 for pain and range of motion (P<.05) Steroid vs C1:no difference (P=.0268) | Triamcinolone and diclofenac are equivalent, and superior to placebo3 |
| S1:triamcinolone, 1% lidocaine, naproxen (25) S2:triamcinolone, 1% lidocaine, placebo (25) | C1:1% lidocaine, naproxen (25) C2:1% lidocaine, placebo (25) | 4 wks | S1 superior to S2, C1, C2 S2 superior to C1, C2 For pain and clinical index at 2 and 4 wks, P<.05 | Triamcinolone and naproxen superior to placebo.More severe cases see most benefit4 |
| Triamcinolone, placebo tabs (15); reinjection at 3 wks if not better | Saline injection, indomethacin (15); reinjection at 3 wks if not | 6 wks | Pain and global scores improved in both groups (P<0.05), but no difference between them (P>.05) | No difference between indomethacin andtriamcinolone better injection11 |
| S1:methylprednisolone, lidocaine, placebo tabs (12) S2:methylprednisolone, NSAID (12) | C1:acupuncture (12) C2:ultrasound (12) C3:placebo tab, placebo U/S (12) | 4 wks | All patients improved. No differences in pain scores or abduction measurements at 2 or 4 wks (P=n/a) | Painful stiff shoulder may be self-limiting condition and bene- ficial effect may be natural recovery12 |
| Methylprednisolone, 1% lidocaine (104) | Physiotherapy (103) | 6 mos, option of other therapies given at 6 weeks | No differences in disability scores 6 wks:mean difference= –.05 (95% CI, –.02 to 3.0) 6 mos:mean difference= 1.4 (95% CI, –0.2 to 3.0) (7) episodes of unilateral | Physiotherapy and steroid injection were of similar short- and long-term effectiveness for treating new shoulder pain |
| Triamcinolone, 1% lidocaine (19) | 1% lidocaine (21) | Mean:33 wk; range:12–52 wk | Steroid:significant improvements of pain (P<.005) and range of motion (P<.005) vs control.No difference in activities of daily living seen (13) | Subacromial injection of steroids is effective for short-term therapy of impingement syndrome |