A pyrocarbon shoulder replacement replaces only the humeral side of the shoulder (the “ball”) with a smooth, carbon-surfaced implant and retains your native glenoid. In patients under 60, this may last as long (or longer) as a traditional shoulder replacement.

• What is it? The formal name is pyrocarbon hemiarthroplasty. “Hemi” means half. The surgeon replaces the arthritic humeral head or “ball” with a stem and a new pyrolytic carbon head or “ball” and does not put in a plastic glenoid component.
• How does it compare with an anatomic total shoulder replacement? In large registries of younger patients, the chance of needing another operation within ten years is lower. A total shoulder tends to give somewhat better function on average, and the two implants fail in different ways.
• What decides how well it works? Sizing and positioning the new ball correctly matters most, along with the shape of the socket. The socket still wears, but slowly, and most of the wear happens in the first year.

What is a pyrocarbon shoulder replacement?

The shoulder is a ball-and-socket joint. The ball is the humeral head, the top of the upper arm bone. The socket is the glenoid, a shallow dish on the shoulder blade. In arthritis, the smooth cartilage covering both surfaces wears away and bone rubs on bone.

An anatomic total shoulder replacement, or anatomic TSA, replaces both sides. A metal ball goes on the arm bone, and a plastic (polyethylene) component is cemented into the socket. “Anatomic” means the ball stays on the arm and the socket stays on the shoulder blade, as in a normal shoulder. A reverse shoulder replacement swaps them — see What Is a Reverse Shoulder Replacement?

A pyrocarbon hemiarthroplasty replaces only the ball. The implant has a graphite core with an outer layer of pyrolytic carbon, a very hard and very smooth form of carbon. Your own socket stays, and the new ball glides against it.

It comes in two designs:

• Stemmed pyrocarbon head. The pyrocarbon ball sits on a thin metal tray attached to a stem placed down the canal of the arm bone.
• Pyrocarbon resurfacing cap. A pyrocarbon cap fits over the reshaped head of the arm bone, held by a short post, with no stem.

The stemmed design is the one cleared by the FDA for use in the United States.

Why not just replace both sides?

Total shoulder replacement is the standard operation for shoulder arthritis, and it works well. Its weak point in younger patients is the plastic socket. Over years of use, the cemented socket component can loosen from the bone. Loosening is among the leading reasons a total shoulder is redone in younger patients [3][5].

Patients under 60 live longer with their implant and usually ask more of it. That means more years of load on the socket component. A pyrocarbon hemiarthroplasty avoids putting plastic and cement in the socket at all.

The trade-off is that your own socket now carries the load. The reason for choosing pyrocarbon over a metal ball is that pyrocarbon wears cartilage much less than metal in laboratory testing [15]. Socket wear still happens after a pyrocarbon replacement, but it is slower.

How does it compare with a total shoulder replacement in patients under 60?

How long it lasts

Australia’s national joint registry compared 403 pyrocarbon resurfacing caps with 1,952 total shoulders in patients under 65. The total shoulders came from the five designs with the lowest revision rates in the registry. At ten years, 7.7% of the pyrocarbon group and 9.0% of the total shoulder group had needed another operation. The difference was not statistically significant [3]. More than nine in ten patients in both groups still had their original implant.

The stemmed design shows the same pattern. In Australia, stemmed pyrocarbon heads in patients under 55 were revised at a rate no different from total shoulders [5]. In New Zealand, revision rates were similar for stemmed pyrocarbon heads and total shoulders in patients under 60 [4].

In one series of 103 shoulders in young, active patients, 94% still had their original stemmed pyrocarbon implant at five years and 89% at ten years [1].

How well the shoulder works

Here the total shoulder has the edge. In New Zealand’s registry, patients under 60 with a total shoulder scored better on a standard shoulder questionnaire than matched patients with a stemmed pyrocarbon head. The gap was large enough for patients to notice [4]. A smaller study comparing implant types found greater improvement in function and pain after total shoulder replacement [6].

That does not mean pyrocarbon patients do poorly. In the series of 103 shoulders, 88% of patients were satisfied. Of those still working, 92% went back to work, and of those playing sports, 93% went back to sport [1].

How each one fails

Option	What is replaced	Main reasons it is redone	Longest follow-up in these studies
Stemmed pyrocarbon head	Ball only, with a stem in the arm bone	Instability, pain, socket wear, a ball that is too large	10 years, one surgical series
Pyrocarbon resurfacing cap	Surface of the ball only, no stem	Implant breakage, pain	10 years, Australian registry
Anatomic total shoulder	Ball and socket, with a plastic socket component	Socket loosening, instability	10 years, same Australian registry comparison

Sources for the table: [1][3][5][7][17].

Who is a good candidate?

The patients in these studies were mostly in their early to mid 50s [1][3][7][8]. The most common reason for the operation is osteoarthritis. It is also used for avascular necrosis, where part of the ball collapses after losing its blood supply. Other uses are arthritis after a fracture and arthritis after repeated dislocations [13]. Patients whose arthritis followed a fracture scored lower in the early months than patients with osteoarthritis or avascular necrosis [13].

The shape of the socket matters. In many arthritic shoulders, the socket wears unevenly toward the back, and the ball drifts backward with it. Surgeons can correct this with reaming, which means smoothing the socket with a rounded cutting tool so it is centered and matches the new ball. In young patients with this wear pattern, reaming combined with a pyrocarbon head did not shorten implant survival [1]. In a separate group of 41 such shoulders, 95% still had their implant at an average of four and a half years [14].

Choosing between a pyrocarbon hemiarthroplasty and a total shoulder depends on the shape of the socket, the condition of the shoulder, activity level, and what the patient most wants to protect against. That decision is made with a surgeon after an examination and imaging.

What can go wrong?

The socket still wears

Pyrocarbon slows socket wear. It does not stop it. Across 12 studies and 536 patients, about one in five showed some socket erosion on x-ray at two years or later [10]. Erosion means the socket bone thins and the ball sits slightly deeper toward the body.

The pattern matters as much as the presence. In a group followed for five and a half years, the socket wore about 1.4 mm on average, and more than half of that wear happened in the first year [9]. In another group, the ball kept moving inward slowly between two years and about six years, by roughly a millimeter on average [8].

Erosion that keeps progressing does matter. Patients whose erosion increased over time had more pain, worse function, and a higher chance of another operation [1].

A ball that is too large

The strongest finding in this research is about sizing, not material. In the stemmed design, the pyrocarbon ball sits on a metal tray about 1.5 mm thick. That added thickness can make the new ball larger than the patient’s original one [2]. An oversized ball overstuffs the joint. It presses harder on the socket and puts tension on the surrounding tendons.

In one series, the ball ended up oversized or out of position in 29% of shoulders. Those patients had worse function, more complications, and more revisions [2]. In the later series of 103 shoulders, oversizing occurred in 24%. One in four of those shoulders needed another operation, compared with fewer than 2 in 100 when the ball matched the original anatomy [1].

Pyrocarbon does not protect the socket when the ball is too big. Head size and position are the central part of planning and performing the operation.

Infection and pain

Infection can occur after any joint replacement. In the US multicenter study of 157 patients, the three shoulders redone in the first two years were revised for pain or low-grade infection [7]. How these infections are prevented, found, and treated is covered in Can a Shoulder Replacement Get Infected?

What happens if a pyrocarbon replacement fails?

Most failed pyrocarbon replacements are converted to a total or reverse shoulder replacement. Across 12 studies, 63% of revisions were conversions to a reverse or total shoulder [10]. In the series of 103 shoulders, six of the seven revisions became reverse replacements. Those revisions happened on average about two and a half years after the first surgery [1].

The stemmed design uses a stem intended to be convertible, so a surgeon can later add a socket component or change to a reverse replacement.

These studies do not report how patients did after conversion compared with patients who had a total shoulder from the start.

How much is known about the long term?

Most results run five to ten years. Ten-year data come from one surgical group’s series and from the Australian registry [1][3]. Patients under 60 usually need a shoulder replacement to last well beyond that. Implant designs and surgical technique have also changed over the years these patients were treated, so older results may not fully reflect current implants.

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Midhat Patel, MD is a fellowship-trained shoulder and elbow surgeon at Banner Health in Phoenix and Scottsdale, Arizona, and a Clinical Assistant Professor of Orthopaedic Surgery at the University of Arizona College of Medicine – Phoenix.

Sources

1. Stemmed pyrocarbon survival, oversizing, return to work and sport. Boileau P, Cointat C, Raynier JL, Schippers P, Ranieri R. Pyrocarbon hemiarthroplasty for the treatment of shoulder osteoarthritis in young, active patients: survival and risk factors for revision. J Shoulder Elbow Surg. 2026;35(2):421–437. Prospective consecutive series, 103 shoulders (96 patients), mean age 56 ± 8 years, mean follow-up 5.6 years (2–10). Revision-free 94% at 5 years, 89% at 10 years; 7 revisions (6 to reverse, 1 to anatomic TSA), mean 31 months. Nonanatomic reconstruction with head oversizing in 24%: increased glenoid erosion OR 3.46 (95% CI 1.13–10.55, p = .0295); revision 25% vs 1.3% (p < .001). Progressive erosion: revision-free 72% vs 97% (p = .002). No survival difference with or without glenoid reaming. Satisfied 88% (91/103); return to work 92% (73/79); return to sport 93% (55/59). doi:10.1016/j.jse.2025.06.021
2. Metal tray as cause of oversizing; nonanatomic reconstruction. Cointat C, Raynier JL, Vasseur H, Lareyre F, Raffort J, Gauci MO, Boileau P. Short-term outcomes and survival of pyrocarbon hemiarthroplasty in the young arthritic shoulder. J Shoulder Elbow Surg. 2022;31(1):113–122. Consecutive series, 64 patients aged ≤60 (mean 53), mean follow-up 33 months (24–60). Survival 92%; 5 revisions at mean 24 months. Nonanatomic reconstruction (center of rotation >3 mm from anatomic) in 29% (18/62), associated with lower function, more complications (subscapularis insufficiency, symptomatic erosion), and higher revision risk. 1.5-mm metal disc identified as main cause of oversizing. Return to work 91%, sport 88%. doi:10.1016/j.jse.2021.06.002
3. Pyrocarbon resurfacing vs anatomic TSA, 10-year revision; failure modes. McBride A, Hurley R, Gill D, et al. Outcomes of pyrolytic carbon humeral resurfacing hemiarthroplasty compared to best-in-class total shoulder arthroplasty in young patients with osteoarthritis: analysis from the Australian Orthopaedic Association National Joint Replacement Registry. J Shoulder Elbow Surg. 2026;35(5):1209–1218. National registry, patients <65 with OA, 2004–2022. 403 pyrocarbon resurfacings (mean age 52.5) vs 1,952 anatomic TSAs from the 5 prosthesis combinations with lowest 5-year cumulative percent revision, cemented polyethylene glenoids (mean age 58.6). 10-year cumulative percent revision 7.7% (95% CI 4.7–12.4) vs 9.0% (95% CI 7.4–11.0); revision risk did not differ (Cox models adjusted for age and sex). Leading revision cause: implant breakage 35% of pyrocarbon revisions; loosening 33.9% of TSA revisions. doi:10.1016/j.jse.2025.09.007
4. Stemmed pyrocarbon vs anatomic TSA under 60: function and revision. Gao R, Viswanath A, Frampton CM, Poon PC. Short-term outcomes following 159 stemmed pyrolytic carbon shoulder hemiarthroplasties and how they compare with conventional hemiarthroplasties and total shoulder arthroplasties in patients younger than 60 years with osteoarthritis: results from the New Zealand National Joint Registry. J Shoulder Elbow Surg. 2023;32(8):1594–1600. National registry, 2000–2022. 159 stemmed pyrocarbon hemiarthroplasties, 5 revisions, 97% retention. Matched cohort <60 with OA: 48 pyrocarbon, 150 conventional HA, 550 aTSA. aTSA superior Oxford Shoulder Score vs pyrocarbon, difference exceeding MCID of 4.3. No difference in revisions per 100 component-years. doi:10.1016/j.jse.2023.01.020
5. Stemmed pyrocarbon vs TSA under 55; TSA revision reasons. Khoriati AA, McBride AP, Ross M, et al. Survivorship of shoulder arthroplasty in young patients with osteoarthritis: an analysis of the Australian Orthopaedic Association National Joint Replacement Registry. J Shoulder Elbow Surg. 2023;32(10):2105–2114. National registry, patients <55 with OA, 1999–2021, 1,564 procedures (159 stemmed pyrocarbon, 714 TSA, 260 reverse). No significant difference in revision rate for stemmed pyrocarbon or TSA when each compared with reverse. Leading revision causes: stemmed pyrocarbon, instability/dislocation 28.6%; TSA, instability/dislocation 20.6% and loosening 18.6%. Authors note lack of long-term data for stemmed pyrocarbon.
6. TSA vs pyrocarbon hemiarthroplasty function in a comparative series. Kleim BD, Garving C, Brunner UH. RSA, TSA and PyC hemi-prostheses: comparing indications and clinical outcomes using a second-generation modular short-stem shoulder prosthesis. Arch Orthop Trauma Surg. 2021. Comparative cohort; TSA showed significantly greater Constant score and pain improvement than pyrocarbon hemiarthroplasty.
7. US multicenter study: patient age, early revisions for pain or infection. Hatzidakis AM, Garrigues GE, Mauter LA, de Gast A, Venegoni MR, Yang Y, Johnston PS. Clinical outcomes of pyrocarbon hemiarthroplasty: a short-term, multicenter study. J Bone Joint Surg Am. 2026;108(8):572–583. Prospective single-arm IDE study, 157 patients at 18 sites, enrolled 2015–2017, mean age 52.4 ± 10.9 (19–73). Mean follow-up 24.4 ± 1.2 months; 10 lost to follow-up; 3 revisions before 24 months for pain or low-grade infection. Composite Clinical Success 82.7% vs 66.8% for propensity score subclassification–derived historical cobalt-chromium HA cohort (n = 169), p < .001. Level III. doi:10.2106/JBJS.25.00054
8. Continued slow medialization at mid-term. Griswold BG, Berger JM, Davis BP, et al. Five-year radiographic and clinical outcomes of pyrocarbon hemiarthroplasty for glenohumeral arthritis and osteonecrosis. J Bone Joint Surg Am. 2025;107(24):2751–2762. Prospective cohort, 45 patients, mean age 52, mean follow-up 73 months. 7-year revision-free survival 95.7%. Humeral head medialization 2.9 ± 2.8 mm at 2 years to 4.0 ± 3.3 mm at final follow-up (p = .096). Acromiohumeral distance decreased >2 mm in 82.2% (p < .001). Glenoid morphology stable in most. Level II. doi:10.2106/JBJS.25.00163
9. Most socket wear occurs in the first year. Kleim BD, Zolotar A, Hinz M, Nadjar R, Siebenlist S, Brunner UH. Pyrocarbon hemiprostheses show little glenoid erosion and good clinical function at 5.5 years of follow-up. J Shoulder Elbow Surg. 2024;33(1):55–64. Single-center consecutive cohort, 31 of 34 patients (91%), mean follow-up 5.5 years (3.5–7). Mean medial glenoid erosion 1.4 mm; 0.8 mm in year 1 vs average 0.3 mm/year (p < .001). Implant survival 100%. Constant score 45.0 to 78.8; VAS pain 6.7 to 2.2 (p < .001). doi:10.1016/j.jse.2023.05.027
10. Erosion prevalence; conversion after failure. Park CN, Zhang GX, Chang J, et al. Pyrocarbon hemiarthroplasty of the shoulder: a systematic review and meta-analyses of clinical results. J Shoulder Elbow Surg. 2023. 12 studies, 536 patients, minimum 24-month follow-up; not restricted to patients under 60. Radiographic glenoid erosion 22.8%; implant position change 10.4%; tuberosity thinning 9.9%. Complication rate 8.6%; revision rate 7.7% (n = 41), 63% (n = 26) converted to reverse or total shoulder arthroplasty.
11. Rationale: lower cartilage wear in laboratory testing. McBride AP, Ross M, Hoy G, et al. Mid-term outcomes of pyrolytic carbon humeral resurfacing hemiarthroplasty compared with metal humeral resurfacing and metal stemmed hemiarthroplasty for osteoarthritis in young patients: analysis from the Australian Orthopaedic Association National Joint Replacement Registry. J Shoulder Elbow Surg. 2022;31(4):755–762. Cited here for its background statement that pyrocarbon was proposed because of markedly reduced wear rates in vitro. doi:10.1016/j.jse.2021.08.017
12. Reaming for posteriorly worn sockets. Ranieri R, Cointat C, Lacouture-Suarez JD, Boileau P. B2 and B3 glenoid osteoarthritis: outcomes of corrective and concentric (C2) reaming of the glenoid combined with pyrocarbon hemiarthroplasty. J Shoulder Elbow Surg. 2025;34(3):726–738. Prospective CT-based cohort, 41 shoulders (35 patients), mean age 57.9, mean follow-up 4.5 years (2–9.5). Survival 95% (39/41); no revision for painful glenoid erosion. Glenoid retroversion 17.1° to 8.3° (p = .001). Total medialization 3.7 ± 3.2 mm (2.0 mm reaming, 1.7 mm erosion). Return to work 84%; all returned to sport. doi:10.1016/j.jse.2024.06.028
13. US regulatory status of the stemmed design. U.S. Food and Drug Administration. De Novo classification request for Tornier Pyrocarbon Humeral Head. DEN220012. Center for Devices and Radiological Health; 2022. Regulatory document, not peer-reviewed.
14. Resurfacing cap survival and implant fracture in a contemporary series. Hoy G, Burrows K, McBride A, Ross M, Davis K, Warby S. PyroTITAN pyrocarbon shoulder hemiarthroplasty: clinical and radiographic outcomes with medium-term follow-up. J Bone Joint Surg Am. Published online May 13, 2026. Prospective single-surgeon cohort, 119 shoulders (115 patients), mean age 56.5. 5-year survival 97.5% (3 revisions). 7 complications (5.9%), including 1 implant fracture. Glenoid erosion increased slightly, not significantly. Level IV. doi:10.2106/JBJS.25.00779
15. Implant fracture now uncommon. Kew M. Is pyrocarbon the future? Commentary on an article by Gregory Hoy, et al.: “PyroTITAN Pyrocarbon Hemiarthroplasty. Clinical and Radiographic Outcomes with Medium-Term Follow-up.” J Bone Joint Surg Am. 2026. Invited commentary; notes implant fracture is now an uncommon reason for revision and mean glenoid–spinoglenoid notch distance decrease of 2.01 mm at 3 years in the Hoy cohort.
16. Indications; lower early scores after fracture. Konarski AJ, Mohammed KD. The experience of stemmed pyrocarbon shoulder hemiarthroplasty in New Zealand: ten years of registry data. Bone Joint J. 2026. National registry 2014–2024, 288 stemmed pyrocarbon hemiarthroplasties in 277 patients, mean age 55 (20–86), mean follow-up 50 months. Indications: OA 53.5%, avascular necrosis 18.1%, trauma sequelae 16.7%, recurrent dislocation 13.2%. Oxford Shoulder Score 36.4 at 6 months, 40.8 at 5 years. Revision 0.75 per 100 component-years (95% CI 0.34–1.42). 6-month score lower after trauma than OA (p = .014) or avascular necrosis (p = .020). Use increased 2.3-fold.
17. Resurfacing cap revision reasons. Same registry as source 15. Pyrocarbon resurfacing <55 (n = 163): key revision reasons pain, prosthesis fracture, and infection; no pyrocarbon resurfacing revised for glenoid erosion. Cumulative percent revision at 6 years 8.9%.

Yes, though it is uncommon. Between 1 and 4 out of every 100 shoulder replacements develop a deep infection around the implant. Most are caused by an ordinary skin bacterium (Cutibacterium acnes) that produces no fever, no redness, and no drainage, which is what makes this infection both difficult to prevent and difficult to recognize.

Three things patients should know:

• What is a periprosthetic joint infection? An infection around an orthopedic joint replacement. Bacteria colonize the surface of the implant itself, not the skin or the incision. Once they establish themselves on metal and plastic, antibiotics alone almost never clear them.
• How do we prevent it? Through a series of small measures that begin well before you reach the operating room. The two with the strongest scientific evidence are the antibiotic given before the incision and allowing three months to pass after a cortisone injection before surgery.
• How do we find it? Slowly, and by assembling several tests rather than relying on one. No single blood test, x-ray, or fluid sample settles the question, and the reason is worth understanding.

What the infection actually is

A shoulder replacement introduces metal and plastic into the joint. If bacteria reach those surfaces, they adhere and build a protective layer over themselves, a structure called a biofilm. Beneath that layer the bacteria are very difficult for either the immune system or antibiotics to reach.

This is why a deep implant infection nearly always means further surgery to remove or exchange components. Antibiotics alone do not penetrate the biofilm, and your body cannot clear the organism on its own.

Why this particular organism is so troublesome

The bacterium responsible in most cases is Cutibacterium acnes, the same organism involved in ordinary acne. It resides in the sebaceous glands of the skin, and those glands are unusually concentrated across the chest, shoulder, and upper back. This leads to three challenges.

1. It is already present. It lives in the skin of almost all patients. A review of 80 studies found it on shoulder skin before any washing roughly half the time, in people who were entirely healthy.
2. Surface cleaning solutions cannot reach all of it. Antiseptic solutions clean the surface of the skin. The bacteria sit in the glands beneath it and repopulate the surface within the hour.
3. It causes almost no immune response. No fever, no pus, frequently no abnormal blood work. What it produces instead is pain and stiffness that fail to resolve, which is easily mistaken for a mechanical problem with the implant.

How we prevent it

Before you reach the operating room

Timing after a cortisone injection. Corticosteroid injected into a joint suppresses the local immune response, and this can increase infection. Analyses of large insurance and Medicare databases have consistently found higher rates of infection and revision when shoulder replacement follows an injection by less than three months, with odds roughly doubled. Beyond three months, the association is much weaker.

Limiting the number of cortisone injections to one. Cortisone is not dangerous, and this is not an argument against using it. However, recent data shows that 2 or more injections in the year before a shoulder replacement increase the risk of a periprosthetic infection.

Washing your shoulder at home before surgery. Most surgeons send patients home with an antiseptic wash to use for several days beforehand. Which one you are handed matters more than it might appear.

Both chlorhexidine soap and benzoyl peroxide are often sent home with patients or purchased over the counter to wash the shoulder once a day for several days before surgery. Benzoyl peroxide is stronger and has better evidence to support it but can cause skin irritation.

Your general health. Nonmodifiable risk factors for infection include previous surgery and male gender. We can’t change those, but we can change some things. Modifiable risk factors include smoking, testosterone use, and poorly controlled diabetes. These are taken into consideration prior to surgery, with many surgeons working with patients to reduce risk by treating these preoperatively.

In the operating room

The antibiotic given before the incision. This is the single most important thing we do. All patients receive IV antibiotics within one hour of surgery. Cefazolin is the best antibiotic for this — a study of 7,713 shoulder replacements at one institution showed that patients who received cefazolin had roughly two-thirds less infection than those who received a substitute.

The patients who receive a substitute almost always have a penicillin allergy in their chart, which is often inaccurate. If your penicillin allergy dates to childhood and has never been confirmed, it is worth asking about. This is one of the few points in the process where a patient asking a single question can measurably reduce their own risk.

Skin preparation. The shoulder is painted with an antiseptic solution before draping. Chlorhexidine combined with alcohol removes more total bacteria from shoulder skin than iodine-based solutions, which is why it has become standard. Adding hydrogen peroxide appears to help further when applied to intact skin before the incision.

Opening the skin. Some surgeons make the incision with electrocautery rather than a scalpel, on the reasoning that heat sterilizes the cut edge. It does. Whether that advantage persists through the remainder of the operation is less certain.

Limiting exposure. Longer operations mean more time for contamination, and more handling of tissue means more opportunity for the organism to travel from the cut skin edge onto gloves, instruments, and eventually the implant. Efficiency is itself a prevention measure.

Antibiotic powder in the wound. Some surgeons place vancomycin powder in the wound before closing. The evidence here is genuinely divided, and the largest study, covering more than 28,000 replacements, found no benefit.

Other things. Washing the wound with iodine or chlorhexidine-based solutions, peroxide, frequently changing gloves, and minimizing implant contact with skin are all frequently used measures to help reduce rates of infection.

What this means

No single item on this list is decisive. Infection after shoulder replacement was uncommon before most of these measures existed and remains uncommon now.

Prevention in this setting is a matter of stacking small advantages rather than deploying one intervention that solves the problem.

Prevention, at a glance

Measure	What it does	Strength of evidence
Cefazolin before the incision	Kills bacteria before they reach the implant	Strong
Testing an unconfirmed penicillin allergy	Permits the more effective antibiotic to be used	Strong
Allowing 3 months after a cortisone injection	Avoids operating on a recently immunosuppressed joint	Strong
Smoking cessation, glycemic control	Improves healing and immune function	Strong
Benzoyl peroxide wash at home	Penetrates the sebaceous glands where the organism lives	Good, may cause skin irritation
Chlorhexidine wash at home	Cleans the skin surface	Good
Chlorhexidine-alcohol prep in the OR	Reduces overall bacterial load at the incision	Good
Hydrogen peroxide before incision	Extends reach into the skin	Moderate
Electrocautery incision	Sterilizes the cut dermal edge	Moderate
Vancomycin powder in the wound	Delivers antibiotic directly into the joint	Moderate

How we diagnose an infection after a shoulder replacement

This can sometimes be very difficult, and where there’s a difference between bacteria living in or around the shoulder and a true infection.

Growing a bacterium from a sample is not the same as having an infection. This organism lives on everyone. It is recovered from operating room air roughly 10% of the time and from deep tissue during routine first-time shoulder replacements about a third of the time, in patients who never develop any problem. A single positive bacterial culture is therefore a clue rather than a verdict, and the entire diagnostic process is built around separating a true infection from an organism that simply happened to be present.

What patients notice

In many cases, the infection isn’t subtle. Redness, swelling, wound drainage, fevers, and extreme pain can all point to an acute infection with C acnes or something different, like MRSA.

In other cases, pain and stiffness, and the pattern of the symptoms, matter more. Pain that never resolved after the original surgery, or that resolved and returned months later, is the characteristic. Stiffness that will not yield counts as well. The other findings people associate with infection (redness, warmth, swelling) are usually absent, which is why these patients are often worked up for implant loosening or instability first.

Blood tests

The standard markers, ESR and CRP, measure inflammation. In some cases, a shoulder infection generates so little of it that the tests frequently remain normal. In one series of revision shoulder surgeries, the better performing test of the two still missed roughly a third of proven infections, and other markers have performed worse, including one that identified only 1 infection in 7.

A normal result does not clear you. That is the single most important thing to understand about blood work in this setting.

X-rays

More useful than their simplicity suggests. The finding that carries the most weight is loosening of the humeral stem, the component seated in the arm bone. That component rarely loosens on its own in the absence of infection, so loosening on an X-ray moves infection substantially up the differential.

Aspiration: drawing fluid from the joint with a needle

This sounds as though it ought to settle the question. It does not. This is where fluid is drawn from the shoulder and sent off for various tests.

In a series of 106 shoulder aspirations performed before revision surgery, 24 shoulders proved to be infected, and the fluid tests identified only 10 of them. It therefore misses roughly two of every three infections. When it does return positive, however, it is correct about 98% of the time.

That asymmetry is the useful part. A positive aspiration carries considerable weight. A negative one carries very little and should never be treated as clearance.

Cultures taken during surgery

At the time of revision surgery, at least five tissue specimens are taken from separate locations and sent to the laboratory for bacterial culture growth, especially when the cause for revision is uncertain.

Two pieces of information separate a true infection from a specimen that merely picked up a passenger:

• How many specimens grew. One positive out of five describes a very different situation from five out of five.
• How quickly they grew. Specimens that grow quickly (within the first few days) are a sign of a true infection, while specimens that grow later may be contaminants.

How much of this is noise

In one carefully controlled study, surgeons took tissue specimens during 117 routine shoulder operations on patients with no evidence of infection. About 1 in 5 grew bacteria. The same team cultured 54 sterile sponges that never touched a patient, and about 1 in 8 of those grew bacteria as well.

That study was small, and it does not establish that a positive culture in a symptomatic patient is meaningless. What it does establish is that a single positive result, standing alone, cannot be trusted, which is precisely why the number of positive specimens and the speed of growth carry as much weight as the result itself.

In 2018, an international consensus group produced criteria specific to the shoulder. Three findings confirm infection outright: a sinus tract draining pus from the implant to the skin, visible pus within the joint, or two specimens growing the same virulent organism. Everything else earns points, and the total yields a verdict of probable, possible, or unlikely. It is a formal acknowledgment that no single finding decides the matter.

Tests, at a glance

Test	How often it identifies a true infection	Reliability when positive	Bottom line
Blood tests (CRP, ESR)	About 2 in 3	Frequently wrong	Normal results do not clear you
X-ray showing a loose humeral stem	Variable	Strongly suggestive	Inexpensive and underrated
Needle aspiration of the joint	About 1 in 3	Almost always correct	A positive means a great deal, a negative very little
Five tissue specimens at surgery	The gold standard	The gold standard	Read alongside how many grew and how quickly

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Midhat Patel, MD is a fellowship-trained shoulder and elbow surgeon at Banner Health in Phoenix and Scottsdale, Arizona, and a Clinical Assistant Professor of Orthopaedic Surgery at the University of Arizona College of Medicine – Phoenix.

Sources

Figures quoted above, with the underlying study detail.

• Antibiotic choice. Marigi EM, et al. Antibiotic prophylaxis with cefazolin is associated with lower shoulder periprosthetic joint infection rates than non-cefazolin alternatives. J Bone Joint Surg Am. 2022;104(10):872–880. Single-institution registry, 7,713 primary shoulder arthroplasties, minimum 2-year follow-up. Infection rate 1.3%. Cefazolin associated with 69% lower all-cause infection risk and 78% lower C. acnes infection risk. Vancomycin hazard ratio 2.32 (95% CI, 1.22–4.40); clindamycin 5.07 (95% CI, 2.83–9.05). doi:10.2106/JBJS.21.00445
• Penicillin allergy testing. Wyles CC, et al. 2019 John Charnley Award. Bone Joint J. 2019;101-B(6 Supple B):9–15. Of 2,576 allergy-tested patients, 2,493 (97%) cleared for cephalosporins.
• Cefazolin despite a documented cephalosporin allergy. Jolissaint JE, et al. J Bone Joint Surg Am. 2026. 482 patients with documented cephalosporin allergy given cefazolin; 0.0% allergic reactions versus 0.51% (4 of 786) on alternative antibiotics.
• Cortisone timing, three-month interval. Werner BC, et al. The timing of elective shoulder surgery after shoulder injection affects postoperative infection risk in Medicare patients. J Shoulder Elbow Surg. 2016;25(3):390–397. Arthroplasty within 3 months of injection: infection 3.0% at 3 months (OR 2.0, p = .007) and 4.6% at 6 months (OR 2.0, p = .001) versus matched controls. No association when surgery occurred more than 3 months after injection. doi:10.1016/j.jse.2015.08.039
• Cortisone timing, revision endpoint. Stadecker M, et al. Bone Joint J. 2022;104-B(5):620–626. 4,252 patients; injection within 3 months carried odds ratio 2.61 for all-cause revision (95% CI, 1.77–3.28), with 71.4% of revisions attributed to infection. doi:10.1302/0301-620X.104B5.BJJ-2021-0024.R3
• Cortisone timing, narrower window. Baksh N, et al. Arch Orthop Trauma Surg. 2023. 25,422 total shoulder arthroplasties stratified into 0–4, 4–8, and 8–12 week intervals; significant increase confined to the 0–4 week group (OR 2.29 at 1 year; 95% CI, 1.19–3.99). Listed for completeness; the three-month interval above reflects the larger body of evidence and consensus guidance.
• Meta-analysis of injection timing. Schoell K, et al. J Shoulder Elbow Surg. 2024. 7 studies, 136,233 patients; overall odds ratio 1.13 (95% CI, 1.06–1.19), with rates rising as injections approached the date of surgery.
• Patient risk factors. Seok HG, et al. J Clin Med. 2022. Meta-analysis, 8 studies, 420 infected cases and 28,464 controls. · Richards J, et al. Clin Orthop Relat Res. 2014;472(9):2809–2815. 3,906 primary shoulder arthroplasties; male sex hazard ratio 2.59 (95% CI, 1.27–5.31). doi:10.1007/s11999-014-3696-5 · Kunutsor SK, et al. PLoS One. 2016. 66 studies, 512,508 patients; smoking relative risk 1.83 (95% CI, 1.24–2.70).
• Home skin washes. Sewpaul Y, et al. Am J Sports Med. 2024. Network meta-analysis, 17 randomized trials, 1,350 patients. Benzoyl peroxide the only agent significantly reducing positive C. acnes cultures versus placebo or soap and water (odds ratio 0.12; 95% CI, 0.04–0.36).
• Benzoyl peroxide versus chlorhexidine. Kolakowski L, et al. Neer Award 2018. J Shoulder Elbow Surg. 2018. 80 patients randomized, contralateral shoulder as control.
• Operating room skin preparation. Saltzman MD, et al. J Bone Joint Surg Am. 2009;91(8):1949–1953. 150 patients randomized. Positive cultures after preparation: 7% chlorhexidine-alcohol, 19% iodine-alcohol, 31% povidone-iodine. doi:10.2106/JBJS.H.00768
• Hydrogen peroxide, four trials. Chalmers PN, et al. JSES. 2019;28(8):1554–1561 (positive, pre-incision). Stull JD, et al. JSES. 2020;29(2):212–216 (positive, pre-incision, 17.1% vs 34.2%). Grewal G, et al. JSES. 2021;30(8):1827–1833 (negative, applied to dermis after incision). Crutcher WL, et al. JSES. 2024;33(9):1905–1908 (negative, repopulation at 60 minutes 78% in both arms).
• Electrocautery versus scalpel. Kim HM, et al. J Shoulder Elbow Surg. 2024;33(1):6–13. 64 patients randomized. Dermal edge cultures positive in 31% of the scalpel group and 0% of the cautery group; glove cultures identical later in the case. doi:10.1016/j.jse.2023.07.014
• Spread from the cut edge. Moor BK, et al. J Shoulder Elbow Surg. 2021;30(7):1537–1543. Randomized, 108 patients; subcutaneous povidone-iodine reduced contamination of gloves and retractors. doi:10.1016/j.jse.2020.11.018
• Vancomycin powder, positive study. Garofalo R, et al. J Shoulder Elbow Surg. 2023;32(8):1638–1644. Retrospective, 422 treated versus 405 controls, minimum 12 months; 0 versus 13 infections. doi:10.1016/j.jse.2023.02.129
• Vancomycin powder, larger negative study. Joshi T, et al. J Shoulder Elbow Surg. 2025. 28,098 shoulder arthroplasties, propensity-matched; no reduction at 90 days or 2 years.
• Prevalence of the organism. Razi A, et al. J Shoulder Elbow Surg. 2024. Review of 80 studies. C. acnes in operating room air mean 10%, on unprepared skin mean 47%, in deep tissue at primary arthroplasty mean 29%. Unexpected positive cultures not associated with worse outcomes.
• Sterile sponge control study. Mook WR, et al. J Bone Joint Surg Am. 2015;97(12):957–963. 117 open shoulder surgeries with no prior surgery or suspicion of infection. At least one positive tissue culture in 20.5%; positive growth in 13.0% of 54 sterile control sponges (p = 0.234). doi:10.2106/JBJS.N.00784
• False positive rates. McCarroll TR, et al. J Shoulder Elbow Surg. 2020. 95 patients; false-positive rate 17.0% open, 10.4% arthroscopic.
• Serum markers. Siegert P, et al. Arch Orthop Trauma Surg. 2021. 136 revision shoulder arthroplasties. Optimized CRP cutoff of 7.2 mg/L gave 69% sensitivity and 74% specificity.
• Interleukin-6. Villacis D, et al. J Bone Joint Surg Am. 2014;96(1):41–45. 34 patients; sensitivity 0.14, specificity 0.95. doi:10.2106/JBJS.L.01634
• Aspiration accuracy. Hecker A, et al. J Shoulder Elbow Surg. 2020;29(3):516–520. 106 aspirations; 24 shoulders infected, only 10 (42%) yielded organisms. Sensitivity 33%, specificity 98%. doi:10.1016/j.jse.2019.07.016
• Alpha-defensin. Ecker NU, et al. Clin Orthop Relat Res. 2019;477(7):1712–1718. 105 patients, 24 infected. Sensitivity 75% (95% CI, 53–90), specificity 96% (95% CI, 90–99). doi:10.1097/CORR.0000000000000762
• Radiographic findings. Pottinger P, et al. J Bone Joint Surg Am. 2012;94(22):2075–2083. 193 revision shoulder arthroplasties. Male sex, humeral osteolysis, and cloudy fluid each associated with more than a six-fold increase in positive culture. doi:10.2106/JBJS.K.00861
• Speed of culture growth. Frangiamore SJ, et al. J Bone Joint Surg Am. 2015;97(14):1149–1158. 46 revision cases. True positives grew at a median of 5 days (IQR 4–7), probable contaminants at 9 days (IQR 6–12), p = 0.002. None of the 37 true positives appeared after day 11; 44% of contaminants did. doi:10.2106/JBJS.N.00881
• The 2018 criteria. Garrigues GE, et al. J Shoulder Elbow Surg. 2019;28(6):S8–S12. doi:10.1016/j.jse.2019.04.034
• Criteria applied in practice. Crook BS, et al. J Shoulder Elbow Surg. 2025. 386 revision shoulder arthroplasties; 38 (9.8%) definite infection.
• Infection rate in primary replacement. Wright JO, et al. J Shoulder Elbow Surg. 2024;33(3):618–627. doi:10.1016/j.jse.2023.10.019
• Ricchetti ET, Patel M, Sogbein O, Namdari S. Preventative strategies and diagnostic evaluation of postoperative infection including prosthetic joint infection. In: Rockwood and Matsen’s The Shoulder, 7th ed. Elsevier; 2025:Ch 58.