Although there are several entry points for shoulder injections, the posterior subacromial approach is perhaps the easiest ( Figure 4 ) . Furthermore, by angling the needle to the underside of the acromion, the physician can easily verify that the needle is properly positioned and, since the humeral head lies more anteriorally, there is no danger of hitting it. It is important not to inject directly into the tendon and, if resistance to flow is encountered, the needle should be directed away from the site. Some potential weakening of the tendon can occur with injection directly into the rotator cuff. We recommend using 8 to 9 mL of lidocaine (Xylocaine), 1 percent, mixed with 20 mg of triamcinolone (20 mg per mL) or a similar amount of methylprednisolone (Depo-Medrol), 20 mg per mL, or betamethasone (Celestone), 6 mg per mL. The large volume floods the rotator cuff surface. A -in, 22-gauge needle usually works well.
In most cases, bursitis of the shoulder is caused by performing repetitive movements for an extended period of time, such as throwing a baseball, playing tennis, painting, scrubbing, gardening, carpentry, etc. Shoulder bursitis can also be exacerbated by a physical trauma or previous injury to the joint area. Your risk for developing bursitis increases with age as joint components, including the bursa, tend to decline as you get older. People over the age of 40 are at the highest risk for developing bursitis. Shoulder bursitis can also be brought on by other joint conditions such as rheumatoid arthritis, psoriatic arthritis, gout, and thyroid disorder.