Patient Education · Shoulder

Shoulder Impingement & Decompression

The most common reason a shoulder hurts to lift. Here is what is happening, what therapy does, and how we decide whether an operation is right for your shoulder.

Dr. Darin W. Allred Darin W. Allred, MD Board-certified orthopedic surgery & sports medicine
~30 minTypical time for the operation
Therapy firstFor most shoulders, that is where we start
Comfort onlyThe sling is optional after surgery
1–2 weeksTherapy restarts after surgery

What impingement is

Above the ball of your shoulder there is a bony arch, formed by a shelf of the shoulder blade. Your rotator cuff tendon runs through the gap underneath it, cushioned by a slippery sac called the bursa.

That gap is not large. When it narrows, or when the contents swell, the tendon and bursa get pinched every time you lift your arm. The pinching inflames the bursa, the inflamed bursa takes up more room, and around it goes.

Illustration of the rotator cuff tendon pinched under the bony arch of the shoulder
Impingement: the tendon and its cushioning sac pinched in the narrow space under the bony arch every time you lift the arm.

It shows up in a recognizable way:

  • A painful arc. Raising the arm hurts in the middle of the movement — roughly shoulder height — and then eases as you go higher.
  • Pain reaching overhead or behind you — a shelf, a seatbelt, a back pocket.
  • Night pain, especially lying on that side.
  • Pain down the outside of the upper arm, not deep inside the joint.

Several things narrow that space: a bone spur under the arch, a thickened bursa, and — most often, and most fixably — a shoulder blade that is not moving properly. Your shoulder blade is supposed to rotate out of the way as your arm goes up. When the muscles controlling it are weak or the posture is poor, it does not, and the space closes down. That is mechanics, and mechanics respond to training.

What we usually try first

Proper physical therapy — the kind aimed at the shoulder blade and the rotator cuff, not just stretching — is the treatment for impingement. Not the thing you try to satisfy the insurance company. The treatment.

A steroid injection into the bursa often helps considerably, and it is useful information as well as treatment: a shoulder that quiets down with an injection is usually a shoulder whose problem really is in that space.

Something worth knowing about this operation. It used to be one of the most commonly performed in orthopedics. Then several careful trials compared decompression with therapy alone, and with a placebo operation where patients had the anesthetic and the punctures but no bone actually removed. The differences between the groups turned out to be smaller than surgeons had expected.

That research changed how carefully we choose, and I think that is a good thing. It does not mean the operation does not help — it means it helps a narrower group of shoulders than we once assumed, and that working out whether yours is one of them is worth doing properly. If we have been through your imaging and your examination, talked about what you have already tried, and decided together that surgery is the right next step, that decision was made with all of this in mind.

When I do recommend it

  • Several months of genuine therapy has not settled it.
  • An injection helped clearly but only briefly, more than once.
  • Imaging shows a real structural problem — a hooked or spurred arch, a thickened bursa — rather than just pain.
  • Something else needs doing anyway. This is the most common honest reason. Decompression is often done alongside a rotator cuff repair, a biceps procedure, or work on an arthritic joint at the end of the collarbone — and making room for a repaired tendon is worth doing.

How the operation goes

  1. Anesthesia. A nerve block in the side of the neck plus a general anesthetic. You go home the same day.
  2. Arthroscopy. A camera and instruments through two or three small punctures.
  3. Inspect the whole joint first — the cuff, the biceps tendon, the cartilage.
  4. Remove the inflamed bursa, which is often the main pain generator.
  5. Shave the underside of the arch, taking off the spur and flattening the surface so the tendon has room to glide.
  6. Address anything else found, such as the end of the collarbone or a frayed cuff.
Illustration of an inflamed bursa in the shoulder
The inflamed bursa is often the main source of the pain - and it takes up the very space the tendon needs.

Recovery

This is a much easier recovery than a cuff repair, because nothing has been sewn back together and nothing needs protecting.

  • First weekUse the shoulder as your pain allows. The sling is purely for comfort — wear it if it helps, leave it off if it does not. Keep the incisions dry 48 hours, then shower. No soaking for three weeks. Ice generously. Take pain medicine the first evening before the nerve block wears off.
  • 1–2 weeksTherapy starts. Motion first, then the shoulder-blade control work that was the underlying problem in the first place. Follow-up visit around two weeks.
  • 6 weeksMost people are back to ordinary activity, with strength still improving.
  • 3–6 monthsTherapy continues for several months. This is not a quick fix — the operation makes room, and the rehabilitation is what actually changes how your shoulder works.

The risks, honestly

  • It does not fix the pain The most likely disappointment, and the reason for the honest section above. If the pain was coming from the neck, from the joint itself, or from a cuff that needed more than room, decompression will not resolve it.
  • Stiffness Some shoulders get tight afterward, which is why motion starts immediately.
  • Infection Rare with punctures this small.
  • Nerve irritation from the block Usually temporary numbness or a weak patch.
  • Ongoing weakness If the cuff was already frayed, taking pressure off it does not restore its strength.
This page is general education. It describes how I approach this problem and what most patients experience. If anything here does not match what you were told in clinic, ask — your own instructions always come first.