Shoulder arthroplasty and instability: pyrocarbon, reverse, and when to refer after a dislocation

Dr Andrew McBride — shoulder arthroplasty update

Upper-limb / shoulder surgeon. Talk covers hemi-arthroplasty (pyrocarbon), anatomic TSA, reverse TSA, AOANJRR outcomes, 3D planning, navigation, and robotics. Mentions public work at the Princess Alexandra Hospital (PA), Brisbane.

Dr Ezekiel Tan (“Zeke”) — shoulder instability for GPs

Upper-limb surgeon; introduced as the fourth partner in Coastal Orthopaedics. Host briefly jokes about an associate professor title he “gave up.” Talk covers traumatic instability, natural history, Bankart / remplissage / Latarjet, rehab, and multidirectional instability.

Host

Narelle (Gold Coast CPD day host).

Who was speaking

Host Narelle opens the upper-limb block with Dr Andrew McBride on shoulder joint replacement, then Dr Ezekiel Tan (“Zeke”), introduced as the fourth partner in Coastal Orthopaedics, on shoulder instability. McBride mentions still working at the PA in Brisbane. We keep names as given in the recording and do not invent surnames for colleagues mentioned only by first name.

Why shoulder arthroplasty caught up

For years shoulder replacement was the “poor cousin” of hip and knee arthroplasty. McBride’s update: at about 15 years, survivorship and patient-reported outcomes now match other joints. That did not arrive as one breakthrough — it was stepwise: materials, operative technique, surgical planning, navigation, and robotics.

AOANJRR and Oxford Shoulder Score

• Every joint replacement goes onto Australia’s national registry — about 150,000 joints; among the world’s largest. Overseas systems often look to Australian data for prosthesis survival.
• Registries catch failures early. Classic example: the ASR metal-on-metal hip (Adelaide surgeon / DePuy lineage in the talk) — catastrophic failure first flagged by the Australian registry, then withdrawn, then class action.
• Shoulder revision rates for what is done now are better than pre-2016 on the registry.
• Oxford Shoulder Score (pain, function, ADLs; /48): typical pre-op under 25 → population mean around 40 post-op. Does not make the shoulder perfect; improves pain and function for anatomic and reverse alike.
• Patient satisfaction at 12 months: about 85% “much better,” ~8% a little better, ~4% the same; very few worse.

Three replacement options

1. Hemi-arthroplasty — young / high-demand, bone-preserving

• Aimed at young high-demand active patients — especially under 55, and generally under ~65; also considered for older but still very high-demand patients (builder, sailor, rock climber).
• Bone-preserving: glenoid untouched → revision options later (20–30 years).
• Main advance: pyrocarbon head over a graphite core (stem may still be metal). Elastic modulus ~26 vs cobalt chrome ~200 — closer to cortical bone; less glenoid erosion than old metal hemis. No polyethylene.
• Australia ~11 years of use before wider US access. Cited series: ~90–95% survivorship at 7–10 years (French / US FDA-era data mentioned).
• Examples in the talk: bilateral pyrocarbon in a working builder; Paralympic powerlifter (bench press career loads); carpenter still working years later after hemi done as a registrar case.

2. Anatomic total shoulder arthroplasty

• Primary indication: osteoarthritis. Also inflammatory arthritis / AVN — less common now (especially RA with better drugs).
• Needs an intact rotator cuff. Partial-thickness tear / tendinopathy over age 50 is common and does not automatically preclude anatomic TSA. OA is often protective of big cuff tears (stiff, less used shoulder).
• Advances: stemless humeral components (lower revision on registry narrative); best-performing glenoid on registry = all-polyethylene with central peg; crosslinked polyethylene sterilised with >50 kGy radiation — big wear/revision win, analogous to hip arthroplasty’s crosslink story.
• Glenoid poly is cemented; humeral side usually uncemented press-fit (hydroxyapatite coating on stemless).

3. Reverse total shoulder arthroplasty

• Designed primarily for rotator cuff arthropathy: irreparable cuff → unbalanced shoulder → superior migration of the humeral head → new joint under the acromion (“acetabularisation of the acromion”). X-ray looks very different from central-wear OA.
• Also used for severe OA when anatomic reconstruction will not work technically.
• Lineage (cleaned carefully from Otter garble): Charles Neer invented the reverse concept; Paul Grammont popularised a workable design (1970s era in the talk).
• Design shift: original ~155° neck-shaft → modern ~145° / 135° plus lateralisation of the centre of rotation — reduces scapular notching, improves rotator cuff moment arm. Fifth-generation stems now in use.

Planning, navigation, robotics

• 3D pre-op planning is nearly universal for shoulder replacement: position the prosthesis, remove osteophytes in the plan, estimate ROM (IR/ER, abduction, flexion/extension), and check for notching before cutting.
• Navigation: e.g. a European platform involving friend Matthias Sunstein (as named in the talk); US systems also mentioned.
• Robotics: extends navigation — reams and drills the glenoid central hole exactly to plan once scapular registration is done. Accuracy of angulation/translation vs plan is improved in early studies; whether that improves long-term outcomes is still TBD.

When to refer for replacement

Q&A: cuff repair vs reverse

• Most of McBride’s practice is rotator cuff repair or reverse — far more reverses than anatomics/pyrocarbon, because end-stage cuff disease drives replacement referrals.
• Repairability: MRI (retraction, fatty infiltration) plus patient factors — age, diabetes, osteoporosis, smoking.
• McBride: all repairs arthroscopic.
• Zeke: philosophical / shared decision — older patients may go straight to reverse if repair odds are poor; some patients accept higher repair risk to avoid replacement. Reverse recovery is often quicker and more predictable than cuff repair healing.
• Anaesthesia aside: beach-chair position; usually GA + interscalene / brachial plexus block (not spinal). Some colleagues use sedation + block; airway access under drapes favours GA + block for many teams.

Shoulder instability for GPs

Zeke’s framing: instability is a nuanced field — anterior, posterior, multidirectional; surgeons can argue for days. Bulk of work is traumatic instability from the ED. Multidirectional / habitual patterns are harder, low-volume, and solutions are imperfect.

Pathoanatomy and natural history

History, exam, imaging

• History > exam > imaging. First insult (often ABD-ER — diving try, tackle with arm dragged back); frequency (every few years vs weekly/nightly); sport/season/life goals; team pressure and holidays all change decisions.
• Posterior instability is less common and easy to miss — operating for anterior when the problem is posterior fails.
• Exam: direction of instability, apprehension/relocation; big athletes may not demonstrate laxity in clinic despite tackle dead-arm symptoms.
• Imaging preference for instability referrals: X-ray ± CT for bone. MRI is less critical for surgical decision-making here. Ultrasound is not useful for instability (and weak predictive value for cuff too) — Zeke’s colourful aside about not letting a kangaroo tip decide State of Origin.

Non-operative care

• Live with it if risk is low and lifestyle allows (some desk-based patients after a one-off).
• Physio: strengthen deltoid and subscapularis, proprioception, avoid positions of instability.
• Anecdote: AFL first-season player offered early surgery; took the ~5% chance of no further instability and played many seasons without reconstruction — not the usual advice, but shared decision-making.
• Injections do not help instability (not diagnostic either); may help concurrent cuff pain.

Bankart, remplissage, Latarjet

• Arthroscopic Bankart: mobilise labrum, anchors into glenoid, suture labrum ± capsule; allow healing before strengthening.
• Remplissage: advance infraspinatus (~10–15 mm) into the Hill-Sachs defect so it engages less.
• Latarjet: transfer coracoid (with conjoint) to the anterior glenoid — stronger for high-demand / bone loss; lower recurrence (~10% elite) but more complications and slightly higher long-term OA risk. Untreated ongoing instability also drives arthritis.
• Return-to-play at same level often ~85–90% when carefully selected.

Rehab, timing, multidirectional

• Protect soft tissues ~6 weeks (sling for comfort; hand in front of body OK; office work usually fine).
• 6–12 weeks: ROM and control; gentle strengthening if pain-free.
• Then strength / stamina; contact when strong and confident. RTP often 6–8 months (range ~4–12).
• Operate earlier after first dislocation → lower long-term recurrence (~15% cited) vs after multiple (~25–30%); overall ~20% recurrence at 10 years (Marco Scheidt / Berlin–Zurich paper cited).
• Multidirectional: physio first — Sarah Warby (Melbourne); Jo Gibson (UK). Surgery reluctant (~40–60% odds); some patients worsen. Local Gold Coast physios named for geographic convenience (Rob Marshall, Josh Noble / Josh Melrose, Heidi Satter, Yasin Maki — as heard).
• Urgent call for nightly / frequent dislocations. Vague mild symptoms can wait public queue (~8–12 months) or private (~6–10 weeks).

Take-home messages for clinic

1. Shoulder replacement outcomes now match other joints at ~15 years — stepwise gains in materials, technique, planning, navigation, robotics.
2. Match option to patient: pyrocarbon hemi (young/high-demand, bone-preserving); anatomic TSA (OA + intact cuff; stemless + central-peg all-poly + crosslink); reverse (cuff arthropathy / unworkable anatomic).
3. Refer for pain + function loss after physio/simple analgesia; no opioids for chronic MSK; night pain / can’t function → consider replacement.
4. Cuff repairability = MRI + comorbidities; reverse may be quicker/more predictable than repair in older patients.
5. After dislocation: refer early for counselling; history first; X-ray ± CT for bone; skip ultrasound for instability.
6. Surgery ladder: Bankart → ± remplissage → Latarjet for bone loss / high demand; rehab is months, not weeks.
7. Multidirectional: expert physio first; surgery with caution.

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