High-yield overview
Humeral Head Resurfacing Arthroplasty
Bone-preservingStemless cap, native shaft kept
Young patientPreserved head bone stock
Glenoid wearDominant failure mode
Easy revisionConvert to stemmed implant
Key features
What it is
PatternA BONE-PRESERVING humeral arthroplasty: a metallic (or pyrocarbon) CAP resurfaces the reamed humeral head WITHOUT a long intramedullary stem, keeping the metaphysis and shaft - avoiding stem-related complications and preserving bone stock for future revision.
Treatment
Indications
PatternTypically a YOUNGER patient with glenohumeral arthritis and PRESERVED humeral-head bone stock and good geometry; chosen to avoid the stem and (in hemi-resurfacing) the glenoid component, accepting articulation with the native or resurfaced glenoid.
Treatment
Failure mode
PatternGLENOID EROSION and pain when a metal cap articulates with the native glenoid is the dominant failure mode; technical OVERSIZING ('overstuffing') and excessive LATERAL OFFSET accelerate glenoid wear. PYROCARBON bearings reduce wear and revision in registry data.
Treatment
Critical Must-Knows
- Humeral head resurfacing arthroplasty is a BONE-PRESERVING procedure in which a metallic (or pyrocarbon) CAP is fitted over the reamed humeral head WITHOUT a long intramedullary stem - the metaphysis and shaft remain native bone - which avoids stem-related complications (periprosthetic fracture, stem loosening, difficult stem removal) and preserves humeral bone stock, making later revision to a stemmed implant relatively straightforward.
- It is typically chosen for a YOUNGER patient with glenohumeral arthritis who has PRESERVED humeral-head bone stock and acceptable head geometry; the appeal is preserving bone and avoiding both the humeral stem and (in hemi-resurfacing) a glenoid component, while restoring the joint surface.
- The dominant failure mode is GLENOID EROSION and pain that occurs when a metal resurfaced head articulates with the NATIVE GLENOID - this is why registry and comparative studies have NOT shown a survivorship advantage for metal resurfacing over stemmed hemiarthroplasty at mid-term, and why glenoid-side pathology must be considered before choosing a hemi-resurfacing.
- The classic TECHNICAL PITFALLS are getting the head size and position wrong: OVERSIZING the cap ('overstuffing' the joint) and creating excessive LATERAL OFFSET (or varus malposition) increase the load on the glenoid and ACCELERATE GLENOID WEAR - so matching the patient's native head size and offset (and down-sizing rather than up-sizing in resurfacing) is important.
- PYROCARBON (pyrolytic carbon) resurfacing has been proposed to reduce glenoid erosion because of markedly lower wear rates, and registry data (AOANJRR) in patients under 55 show a LOWER revision rate for pyrocarbon hemi-resurfacing (around 8.9% at 6 years) than for metal hemi-resurfacing (around 17.1%) or metal stemmed hemiarthroplasty (around 17.5%), with no pyrocarbon cases revised for glenoid erosion; pain, prosthesis fracture and infection were the main revision reasons.
- A major practical advantage is that, because bone stock and humeral geometry are preserved, a failed resurfacing can usually be CONVERTED relatively straightforwardly to a stemmed anatomic or reverse arthroplasty - so resurfacing can be viewed as a bone-conserving first step in a young patient, provided the surgeon avoids overstuffing and considers the glenoid.
Clinical Pearls
- “Humeral head resurfacing = bone-preserving stemless CAP (native shaft kept) -> avoids stem complications, eases later revision; for younger patients with preserved head bone stock.
- “Dominant failure = GLENOID erosion/pain (metal on native glenoid); no survivorship advantage over stemmed hemi at mid-term; OVERSTUFFING / lateral offset accelerate wear.
- “Pyrocarbon resurfacing lowers wear/revision (AOANJRR ~8.9% vs ~17% at 6y); conversion to stemmed implant is straightforward.
Preserve Bone - But Mind the Glenoid
The appeal
A stemless cap preserves the metaphysis and shaft - no stem complications, and a failed resurfacing converts easily to a stemmed implant. Good for younger patients.
The catch
Glenoid erosion/pain (metal on native glenoid) is the main failure; don't overstuff or over-lateralise the head. Pyrocarbon reduces wear.
Concept, Indications & Failure
A Bone-Preserving Cap - With a Glenoid Caveat
Humeral head resurfacing fits a metallic (or pyrocarbon) cap over the reamed humeral head without a stem, preserving the metaphysis and shaft. The benefits are bone preservation and avoidance of stem-related complications (periprosthetic fracture, stem loosening, hard stem removal), and a failed resurfacing converts relatively easily to a stemmed implant - which makes it attractive in a younger patient with preserved head bone stock. The caveat is the glenoid: when a metal cap articulates with the native glenoid, glenoid erosion and pain are the dominant failure mode, and at mid-term resurfacing has not out-survived stemmed hemiarthroplasty. The classic technical errors - oversizing/overstuffing and excessive lateral offset - increase glenoid load and accelerate wear; pyrocarbon bearings reduce it.
Technique Pearls & Evidence-based Practice
Match the Native Head, Respect the Glenoid
- Match native head size and offset. Reproduce the patient's anatomy; avoid oversizing ('overstuffing') and excessive lateral offset or varus malposition, which increase glenoid load and wear (down-size rather than up-size in resurfacing).
- Assess the glenoid. Glenoid erosion/pain drives failure of hemi-resurfacing - consider glenoid wear, version and bone stock when choosing hemi-resurfacing versus a glenoid-resurfacing or stemmed/total option.
- Consider the bearing. Pyrocarbon resurfacing reduces wear and, in registry data, revision rates - particularly for the goal of avoiding glenoid erosion.
- Plan for the future. Counsel that resurfacing is bone-conserving and convertible to a stemmed anatomic or reverse arthroplasty if it fails - a genuine advantage in a young patient.
The Glenoid Decides the Outcome
The recurring lesson of humeral head resurfacing is that the GLENOID, not the humeral cap, usually decides the outcome: because the dominant failure mode is glenoid erosion and pain when metal articulates with native glenoid, and because resurfacing has not out-survived stemmed hemiarthroplasty at mid-term, the glenoid must be assessed and the head must NOT be overstuffed or over-lateralised - both of which load the glenoid further. Use resurfacing for its real strengths - bone preservation and easy conversion in a young patient - and consider a pyrocarbon bearing or a glenoid-side solution where glenoid wear is the concern, rather than expecting a metal-on-native-glenoid hemi-resurfacing to be durable in every patient.
Evidence & Key Studies
Evidence
Pyrocarbon vs metal humeral resurfacing and metal stemmed hemiarthroplasty in young patients (AOANJRR)
McBride AP, Ross M, Hoy G, Duke P, Page R, Peng Y, Taylor F • Journal of Shoulder and Elbow Surgery (2021)
Key Findings:
- In registry patients under 55 with osteoarthritis, the cumulative revision at 6 years was 8.9% for pyrocarbon hemi-resurfacing, 17.1% for metal hemi-resurfacing and 17.5% for metal stemmed hemiarthroplasty.
- Pyrocarbon hemi-resurfacing had a significantly lower revision rate than other hemi-resurfacing prostheses; pain, prosthesis fracture and infection were the key reasons for revision.
- No pyrocarbon hemi-resurfacing case was revised for glenoid erosion - the failure mode that limits metal-on-native-glenoid resurfacing.
Evidence
Stemmed hemiarthroplasty versus resurfacing in primary shoulder osteoarthritis
Lebon J, Delclaux S, Bonnevialle N, Rongieres M, Bonnevialle P, Mansat P • Orthopaedics & Traumatology: Surgery & Research (2014)
Key Findings:
- Functional scores were similar between resurfacing and 3rd-generation stemmed hemiarthroplasty, but revision-free survival was significantly lower with resurfacing (4 revisions for glenoid wear, 9.8%, versus none).
- Resurfacing showed greater varus positioning and lateral offset of the humeral head than stemmed hemiarthroplasty.
- Greater humeral-head size may increase lateral offset and accelerate glenoid wear; down-sizing the head in resurfacing may limit these complications.
Evidence Attribution
According to PubMed, the registry survivorship figures (pyrocarbon vs metal hemi-resurfacing vs metal stemmed hemiarthroplasty), the reasons for revision and the absence of glenoid-erosion revisions with pyrocarbon come from the cited McBride AOANJRR study; the similar function but poorer revision-free survival of resurfacing (driven by glenoid wear) and the link between greater head size/lateral offset and glenoid wear (favouring down-sizing) from the cited Lebon study. The bone-preserving rationale, stem-avoidance and ease of conversion to a stemmed implant are standard, well-established teaching. (See also our Total Shoulder Arthroplasty and Glenohumeral Osteoarthritis topics.)
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
Viva scenarioStandard
Clinical prompt
“What is humeral head resurfacing arthroplasty and when would you consider it?”
Practical approach
Humeral head resurfacing arthroplasty is a bone-preserving shoulder arthroplasty in which a metallic or pyrocarbon cap is fitted over the reamed humeral head without a long intramedullary stem, so the metaphysis and shaft remain native bone. Its appeal is twofold: it avoids stem-related complications such as periprosthetic fracture and difficult stem removal, and it preserves humeral bone stock, which makes later conversion to a stemmed anatomic or reverse arthroplasty relatively straightforward. For those reasons I would consider it mainly in a younger patient with glenohumeral arthritis who has preserved humeral-head bone stock and acceptable geometry, where preserving bone and avoiding a stem is desirable. The key caveat is the glenoid: when a metal cap articulates with the native glenoid the dominant failure mode is glenoid erosion and pain, and resurfacing has not out-survived stemmed hemiarthroplasty at mid-term, so I would assess the glenoid carefully and consider a pyrocarbon bearing, which in registry data has lower wear and revision and no revisions for glenoid erosion. Technically I would match the native head size and offset and specifically avoid overstuffing or over-lateralising the head, because that accelerates glenoid wear.
Key clinical points
Bone-preserving stemless cap (native shaft kept) - avoids stem complications, eases conversion
Consider in younger patients with preserved head bone stock
Glenoid erosion/pain is the dominant failure; no mid-term survival advantage over stemmed hemi
Match native size/offset (avoid overstuffing); consider pyrocarbon bearing
Common pitfalls
Overstuffing or over-lateralising the head (accelerates glenoid wear)
Ignoring glenoid pathology before a hemi-resurfacing
Expecting durability from metal-on-native-glenoid in every patient
Further questions
“Main failure mode? - Glenoid erosion/pain”
“Bearing that reduces wear? - Pyrocarbon”
Viva scenarioStandard
Clinical prompt
“A young patient's metal hemi-resurfacing has failed with glenoid pain. Why did it fail and what are the revision options?”
Practical approach
The most likely reason is glenoid erosion with pain, which is the dominant failure mode of a metal cap articulating with the native glenoid; this is well recognised, and it is why metal resurfacing has not shown a survivorship advantage over stemmed hemiarthroplasty at mid-term. Contributing technical factors include oversizing the head (overstuffing the joint) and excessive lateral offset or varus malposition, all of which increase the load on the glenoid and accelerate wear. The advantage now is that resurfacing preserves humeral bone stock and geometry, so revision is relatively straightforward: I can convert to a stemmed implant. If the rotator cuff is intact and the glenoid bone is adequate, conversion to an anatomic total shoulder arthroplasty with a glenoid component addresses the eroded glenoid; if the cuff is deficient or the glenoid is badly worn, a reverse total shoulder arthroplasty is the better option. Either way I would assess glenoid bone stock and version on CT, plan glenoid reconstruction or augmentation if needed, and counsel the patient that converting a resurfacing is generally more straightforward than revising a loose stemmed implant because the bone has been preserved.
Key clinical points
Failure: glenoid erosion/pain (metal on native glenoid), worsened by overstuffing/lateral offset
Preserved bone stock makes conversion to a stemmed implant straightforward
Cuff intact + adequate glenoid -> anatomic TSA; cuff-deficient/worn glenoid -> reverse TSA
CT glenoid bone stock/version; plan glenoid reconstruction if needed
Common pitfalls
Repeating a hemi solution for a glenoid-driven failure
Not imaging glenoid bone stock/version before revision
Choosing anatomic TSA with a deficient cuff
Further questions
“Cuff-deficient revision choice? - Reverse total shoulder arthroplasty”
“Why is conversion easier? - Bone stock/geometry preserved”
Mnemonics & Memory Aids
Mnemonic
RESURFACE
R
Remove no stem - bone-preserving cap
E
Erosion of glenoid - the dominant failure
S
Size to native head (avoid OVERSTUFFING)
U
Under-55 / younger patient indication
R
Revision easy (convert to stemmed)
F
Fracture (periprosthetic) avoided - no stem
A
Avoid excess lateral offset/varus
C
Carbon (pyrocarbon) reduces wear
E
Evaluate the glenoid before choosing hemi
Hook:RESURFACE: no stem, Erosion is the enemy, Size to native, Under-55, Revision easy, no Fracture, Avoid offset, Carbon helps, Evaluate glenoid.
Exam day cheat sheet
Shoulder Resurfacing Arthroplasty - Cheat Sheet
Concept & indication
- Bone-preserving metallic/pyrocarbon cap over the humeral head, NO stem
- Avoids stem complications; preserves bone; eases later revision
- Younger patient with preserved head bone stock and geometry
Failure mode
- Glenoid erosion + pain (metal on native glenoid) - dominant failure
- No survivorship advantage over stemmed hemiarthroplasty at mid-term
- Pain, prosthesis fracture, infection also cause revision
Technical pearls
- Match native head size/offset; AVOID oversizing (overstuffing)
- Avoid excess lateral offset/varus (accelerates glenoid wear)
- Assess the glenoid; consider pyrocarbon to reduce wear
Revision
- Preserved bone -> straightforward conversion to stemmed implant
- Cuff intact + adequate glenoid -> anatomic TSA
- Cuff-deficient/worn glenoid -> reverse TSA