Shoulder Replacement

Why the shoulder hurts

Your shoulder is a ball and socket, but a strange one. The socket is shallow — think of a golf ball sitting on a tee rather than a hip's ball buried in a cup. That shallowness is why your shoulder can reach anywhere, and it is also why the joint depends on muscle rather than bone for its stability.

That muscle is the rotator cuff: four muscles wrapping the shoulder blade, their tendons blending into a cuff over the top of the arm bone. The cuff's job is to hold the ball centered on the socket while the big deltoid muscle does the lifting.

Two different problems bring people to shoulder replacement:

• Arthritis with a working cuff. The cartilage wears off the ball and socket. It grinds, it aches deep in the joint, and reaching becomes painful and stiff.
• A rotator cuff that has failed. When the cuff is torn beyond repair, the ball rides up out of position and wears against bone. Strength to lift overhead disappears — some people cannot raise the arm at all, even though the elbow and hand work fine.

Those two problems need two different operations. That is the whole story of anatomic versus reverse.

The anatomic replacement

This is the classic version, and it keeps your natural layout: a metal ball on the top of the arm bone, a smooth plastic socket on the shoulder blade. Ball where the ball was, socket where the socket was.

It works beautifully — but only if your rotator cuff still works, because the implant relies on that cuff to keep the ball centered. That is why I check the cuff carefully before choosing this one.

The reverse replacement

The reverse does something that sounds strange until you see why: it swaps the parts. The ball is attached to the shoulder blade, and the socket goes on top of the arm bone — the opposite of how you were built.

That switch moves the center of the joint and changes the leverage, so the big deltoid muscle can lift the arm all by itself. The rotator cuff is no longer needed for the job. It rescued a group of patients we genuinely could not help before — people with worn-out cuffs who had been told to live with an arm they could not raise.

I also use a reverse for some complex fractures of the shoulder in older patients, and for a replacement that has failed and needs redoing.

Here is the part that surprises people: the "new" operation is holding up at least as well as the classic one. At ten years, about 92% of anatomic replacements and 94% of reverses are still in place. The full numbers are here.

Who it is for — and who should wait

• Deep, constant shoulder pain that runs your day.
• Night pain. Shoulder arthritis is famous for it — people end up sleeping in a recliner long before they come see me.
• You cannot reach where you need to: the seatbelt, the top shelf, behind your back.
• Non-surgical care has had a fair try — activity changes, therapy, anti-inflammatory medicine, sometimes an injection — without enough relief.
• Advanced arthritis or an unfixable cuff on imaging to match those symptoms.

Getting ready: the two-wash routine

Shoulders have an infection problem the hip and knee do not. The skin around the shoulder is oily, and it harbors a slow, quiet bacterium called Cutibacterium acnes that lives down in the oil glands where ordinary soap does not reach. So before shoulder surgery I ask for two different washes for five days:

• Chlorhexidine (CHG), which knocks down the general bacterial load on the skin.
• Benzoyl peroxide — the acne product — because it gets into the oil glands where that particular organism hides.

They do different jobs, which is why I want both. Your pre-op instructions spell out exactly how.

How the operation goes

1. Anesthesia. A nerve block in the side of the neck numbs the whole arm, plus a general anesthetic so you are fully asleep. The block is what makes waking up comfortable.
2. The approach. An incision on the front of the shoulder, working between muscles to reach the joint.
3. The worn ball comes off and the socket is prepared.
4. The implants go in — either the anatomic set (ball on the arm, socket on the blade) or the reverse set (ball on the blade, socket on the arm), depending on what your cuff can do.
5. Motion and stability are checked through the range before closing.
6. Closing. The shoulder is closed in layers under a waterproof dressing you can shower with the next day, and your arm goes into a sling.

Recovery

• Day of surgeryHome the same day or after one night, arm in a sling. Take pain medicine that first evening, before the block quits.
• First 2 weeksThe sling is for comfort and protection, not strict immobilization — wear it out of the house, around pets and grandchildren, and at night early on. Sitting quietly at home, take the arm out and rest it in your lap. Sleep propped up in a recliner or on a wedge of pillows; lying flat is miserable for a week or two. Shower the day after surgery. Aspirin 81 mg twice a day for two weeks. Follow-up around two weeks.
• Week 1 onwardPhysical therapy starts within about a week. Starting early is how we keep the shoulder from stiffening, and therapy continues for several months.
• Through 6 weeksNothing heavier than a coffee cup with that arm. No pushing yourself up out of a chair with it, no pulling heavy doors, no gallon of milk. And avoid your implant's one position — see below. Most people wean out of the sling over about four weeks.
• 6 weeks to 3 monthsStrengthening comes in. Reach and comfort keep improving.
• Long termMost people settle into a 25-pound limit with that arm for good. That covers nearly everything ordinary life asks.

Your one position rule

It depends on which implant you have, and it lasts six weeks:

• Anatomic replacement: avoid reaching behind your back and forcing the arm outward.
• Reverse replacement: avoid reaching behind your back with your elbow tucked in against your body and the arm turned inward.

Both amount to the same practical advice — do not reach around behind yourself and push. Your therapist will show you exactly what yours means.

The risks, honestly

• Infection Uncommon, and the two-wash routine is aimed squarely at it. Shoulder infections tend to be slow and quiet rather than dramatic, which is why we take the skin preparation so seriously.
• Nerve irritation The block affects a bundle of nerves, and some people have lingering numbness or a weak patch for days to weeks. It nearly always settles. A lasting nerve injury is rare.
• Dislocation Uncommon, a little more so with a reverse, and almost always tied to that one forbidden position in the early weeks.
• Stiffness The reason therapy starts within a week rather than a month.
• Fracture Bone can crack while implants are seated, and after a reverse a small bone on top of the shoulder blade can develop a stress fracture months later. Uncommon.
• Loosening or wear over the years Mechanical parts in a mechanical joint. The ten-year numbers above are reassuring, but a revision operation is possible far down the road.
• Blood clots Much less common after shoulder surgery than after hip or knee, but not zero — hence the aspirin and the early movement.

What your new shoulder will feel like

• Pain relief comes first, motion comes later. The ache usually settles well before your reach comes back.
• Reaching behind your back is the motion least likely to fully return, especially after a reverse. Most people trade it happily for a shoulder that does not hurt.
• Clicking is normal. It is metal and plastic.
• Overhead work and heavy lifting stay off the menu long term. Golf, fishing, driving, yard work, and picking up a grandchild carefully are all back on it.
• Dental care: hold off on routine dental work for three months. After that, unless your ability to fight infection is impaired, you do not need antibiotics before dental visits.