Acromioplasty is a surgical procedure that reshapes a small bone on top of your shoulder to create more space for the tendons beneath it. The bone in question, called the acromion, sits like a shelf above the rotator cuff. When its shape causes it to press against those tendons during arm movement, it can lead to chronic pain and restricted motion. The surgery shaves down the underside of this bone to relieve that pressure.
Why Acromion Shape Matters
Not everyone’s acromion looks the same. A widely used classification system describes three main shapes: Type I (flat), Type II (curved), and Type III (hooked). A flat acromion leaves plenty of room for the rotator cuff tendons to glide underneath. A hooked acromion, on the other hand, angles downward and narrows that space considerably.
The shape you’re born with plays a significant role in shoulder problems. Research on full-thickness rotator cuff tears found that nearly 70% occurred in people with hooked (Type III) acromions, compared to about 24% in those with curved acromions and only 3% in those with flat ones. People with hooked acromions are also more likely to eventually need surgery after trying conservative treatment for shoulder impingement. Acromioplasty essentially converts a hooked or curved acromion into a flat one, removing the bony overhang that’s irritating the tendons below.
What the Surgery Actually Does
During an acromioplasty, a surgeon uses a small rotating burr to shave down the front edge and undersurface of the acromion. The goal is to flatten the bone so it no longer digs into the rotator cuff tendons when you raise your arm. A ligament that connects the acromion to another nearby bone is also removed to open up additional space.
The procedure is almost always done arthroscopically, meaning the surgeon works through a few small incisions using a camera and instruments rather than making a large open cut. The burr enters through a small portal on the side of the shoulder. The surgeon starts at the front edge and works backward, grinding the bone down until the underside is smooth and level with the rest of the acromion. The whole process is sometimes called subacromial decompression, since the point is to decompress the space beneath the acromion where tendons pass through.
When Acromioplasty Is Recommended
Acromioplasty is primarily used to treat shoulder impingement syndrome, a condition where the rotator cuff tendons get pinched beneath the acromion during overhead movements. The hallmark symptoms are pain when reaching above your head, weakness in the shoulder, and a dull ache that can worsen at night.
Surgery isn’t the first option. Clinical guidelines require at least six weeks of conservative treatment before acromioplasty is considered. That typically means physical therapy, anti-inflammatory medication, and sometimes corticosteroid injections. The diagnosis also needs to be confirmed through clinical examination and imaging to make sure the rotator cuff itself is intact. Patients with partial-thickness rotator cuff tears or calcific tendinitis generally aren’t good candidates for acromioplasty alone.
It’s also worth noting that guidelines from the American Academy of Orthopaedic Surgeons do not support the routine use of acromioplasty as an add-on to rotator cuff repair for small to medium tears. In those cases, repairing the tendon alone appears to produce similar results. Acromioplasty tends to be most appropriate when impingement is the primary problem and the rotator cuff is still structurally sound.
What Recovery Looks Like
After surgery, your arm will be in a sling for four to six weeks. During that time, you shouldn’t reach, lift, push, or pull with the affected shoulder. You can take the sling off several times a day to bend your elbow, move your fingers, bathe, and dress, but you’ll need to wear it while sleeping.
Ice is important in the first few days. Plan to keep ice on the shoulder for the first 48 to 72 hours, then continue icing two to three times daily during the first week, particularly before bed. This helps manage swelling and pain during the most uncomfortable phase of recovery.
Most people can return to driving within two to four weeks. Light daily activities become possible around the 12-week mark. Vigorous sports and heavy lifting are typically off-limits for four to six months. If the acromioplasty was done alongside a rotator cuff repair, recovery takes longer because the tendon needs six to eight weeks just to heal to the bone, and full recovery from a large tear can stretch to six months or more.
How Effective Is It?
When performed on the right patients, acromioplasty has strong outcomes. A systematic review of arthroscopic subacromial decompression found that patients experienced reduced pain and improved function regardless of age or how long they’d been dealing with symptoms. In one study, roughly 90% of patients reported that their symptoms had improved after surgery, with better range of motion and increased strength in forward arm movements.
Long-term satisfaction is also encouraging. Multiple studies found high patient satisfaction lasting at least six years after surgery, particularly when performed by experienced shoulder surgeons on carefully selected patients. That last part is key: the best results come when the diagnosis is clear, conservative treatment has genuinely been tried, and the rotator cuff is intact.
Complication rates are generally low. Studies report rates ranging from 0% to about 19% depending on the specific technique and patient population, with most large studies landing around 5% for standard arthroscopic decompression. The most common issues are stiffness, persistent pain, and infection, though serious complications are uncommon with this procedure compared to more complex shoulder surgeries.
Acromioplasty vs. Physical Therapy Alone
One of the ongoing questions in orthopedics is whether acromioplasty offers meaningful benefits over physical therapy for impingement. The evidence suggests both approaches produce significant improvement. For patients with intact rotator cuffs who haven’t responded to at least six weeks of dedicated rehab, surgery can provide additional relief. But for many people, a structured physical therapy program focused on strengthening the rotator cuff and improving shoulder mechanics resolves symptoms without any surgical intervention. The decision typically comes down to how much the impingement is affecting your daily life and whether you’ve plateaued with conservative treatment.