Shoulder Hemiarthroplasty (Partial Replacement): Uses, Recovery, Risks and Limits

A shoulder hemiarthroplasty is a partial replacement: the surgeon replaces only the ball at the top of the arm bone (the humeral head) with a metal component and leaves your own socket, the glenoid, in place. A total replacement resurfaces the socket as well, so a hemiarthroplasty replaces half of the joint and relies on the natural socket to work against¹.

When my own shoulder went, I assumed the least drastic option would be to swap out the worn ball and leave the rest alone, and I asked the surgeon about exactly that. He explained why it was not right for me, and in doing so taught me what a hemiarthroplasty actually is and who it suits. This is the plain version of what I learned. For where it sits among the three operations, start with the pillar guide to shoulder replacement; if the socket is worn and the cuff is intact, the operation you are more likely to be offered is a total shoulder replacement.

What is a shoulder hemiarthroplasty?

A hemiarthroplasty replaces only the humeral head with a metal ball, seated on a stem down the arm bone or on a shorter stemless fixation, and leaves the natural glenoid socket untouched. The new metal ball then moves against your own cartilage-lined socket rather than against an artificial one².

That single design choice is the whole story of the operation. Because the socket is your own, a hemiarthroplasty depends on that socket being in reasonable condition, and it depends on the rotator cuff, the group of tendons that centres and moves the ball, still doing its job. Take either of those away and the partial replacement starts to make less sense than a total or a reverse.

When is a hemiarthroplasty the right operation?

The clearest use is a complex fracture of the top of the humerus where the ball is badly broken but the socket is undamaged, so only the ball needs replacing; it is also chosen for some younger patients and for shoulders with a well-preserved socket and a working cuff. Avascular necrosis, where the bone of the humeral head dies while the socket stays healthy, is another situation where replacing just the ball can be enough¹.

Age is part of the thinking here rather than the whole of it. A younger shoulder faces decades of use and possibly more than one operation in a lifetime, so a surgeon may prefer to conserve the socket bone now and keep the bigger operations in reserve. Even so, the honest headline from the arthritis evidence is blunt: patients with osteoarthritis tend to get better and more reliable pain relief from a total replacement than from a hemiarthroplasty¹. That is why partial replacement, once common, has narrowed to a smaller set of shoulders.

Hemiarthroplasty versus a total or reverse replacement

The difference comes down to the socket and the cuff: a hemiarthroplasty replaces the ball only, a total replacement resurfaces the socket as well for a worn arthritic joint with an intact cuff, and a reverse replacement switches the ball and socket so the deltoid muscle can lift the arm when the cuff is gone. The state of the rotator cuff, not age alone, mostly decides which of the three suits a shoulder³.

This is where my own case turned. My socket was worn and my cuff was long past repair, so replacing just the ball would have left the ball grinding on a bad socket with no cuff to control it. The operation that answered both problems was a reverse shoulder replacement, not a partial. In elderly fracture patients too, surgeons increasingly choose a reverse over a hemiarthroplasty, and the trade-off is measurable: one systematic review found reverse arthroplasty gave better forward elevation but carried around four times the odds of a complication compared with hemiarthroplasty⁴.

The operation

A hemiarthroplasty is done under a general anaesthetic, very often combined with a regional nerve block (an interscalene block) that numbs the shoulder afterwards, through a cut at the front of the shoulder, and it takes roughly 1.5 to 2 hours. It is commonly a 1 to 2 night hospital stay, though selected fitter patients now have shoulder replacement as a day case¹.

Less is replaced than in a total, but do not mistake that for a minor procedure. The surgeon still opens the shoulder through the deltopectoral approach, between the deltoid and chest muscles, dislocates the joint to remove and replace the damaged head, and, in a fracture case, has the extra work of reattaching the bony tuberosities that carry the cuff tendons. That tuberosity repair matters, because how well those fragments heal largely sets the final result.

Recovery

The arm rests in a sling for about 2 to 6 weeks, commonly around 3 to 4, while physiotherapy starts early with gentle passive and pendulum movements and builds to active movement and then strengthening over the following months. Most people return to driving around 6 weeks and desk-based work between 2 and 6 weeks, with heavier or overhead work waiting 3 to 6 months².

The pattern that no one quite spells out is how long the settling takes: pain tends to ease first, and the shoulder keeps gaining movement and strength over 6 to 12 months. I found the sling weeks the strangest part, living one-handed and waiting on an arm that did nothing yet, and the slow monthly gains the part I had underestimated. The full stage-by-stage picture is in the week-by-week shoulder replacement recovery, and it applies to a partial much as it does to a total.

How long does it last, and the socket-wear question

Shoulder replacements overall have around 90% still in place at 10 years, but hemiarthroplasty outcomes are more variable, and the specific catch is the retained socket: your own glenoid can wear against the metal ball over the years and become painful. After the first decade the risk of needing a revision runs at roughly 1% per year, so a partial done at a younger age is more likely to need redoing within a lifetime¹.

For a hemiarthroplasty done after a fracture, the durability question is bound up with the bone: reviews report variable long-term results, with many failures traced to the tuberosities healing in the wrong place or not uniting at all⁴. If the socket does wear or the shoulder stays painful, a hemiarthroplasty can often be converted later to a total or a reverse replacement, which is one reason surgeons sometimes favour it in a younger shoulder: it keeps options open.

Risks and complications

A hemiarthroplasty carries the general risks of shoulder replacement, infection in roughly 1 in 100 cases (about 1%, reported from 0 to 4%), a usually temporary stretch of the axillary nerve, stiffness, loosening or wear over time, and periprosthetic fracture, plus the specific problem of painful wear of the retained socket. Deep infection can mean further surgery, and blood clots and the general risks of anaesthesia, though rarer after shoulder than lower-limb surgery, are named honestly too¹.

The socket point is the one worth carrying away, because it is the risk that is unique to leaving your own glenoid in place. It is also why a hemiarthroplasty is judged over years, not weeks: a shoulder that feels good early can still ache later as the socket wears. The wider account of what can go wrong, and how often, sits in the guide to shoulder replacement risks and complications. Whether a partial, a total, or a reverse suits your shoulder is a judgement for a surgeon who can examine the joint and read your own imaging, not one a website can settle for you.