Deltopectoral approach · Grammont design — the deltoid is the motor
- RSA needs a FUNCTIONING DELTOID and an intact AXILLARY NERVE — the deltoid is the sole motor for elevation. Axillary nerve injury is catastrophic and the operation will fail without it.
- The Grammont design medialises the centre of rotation to the glenoid face and distalises the humerus, increasing the deltoid moment arm by 30–40 percent so the deltoid alone can elevate the arm.
- The baseplate must sit FLUSH with the INFERIOR glenoid rim with 5–10 degrees of inferior tilt. A superior baseplate position causes scapular notching in 50–80 percent of cases.
- The axillary nerve runs on the anterior-inferior capsule 5–7 cm below the acromion — protect it during the inferior capsular release, under direct vision.
- TSA needs an intact cuff; RSA is for cuff DEFICIENCY. Instability after RSA is INFERIOR (opposite to TSA, which is posterior) — test it with the arm adducted.
When & Why
Indication. RSA is the operation for the cuff-deficient shoulder. The commonest indication is cuff tear arthropathy (Hamada grade 4–5) — pseudoparalysis (active elevation less than 90 degrees) with superior migration of the humeral head and acetabularisation of the acromion. It is also indicated for: - A massive irreparable rotator cuff tear with pseudoparalysis (elevation less than 90 degrees).
- Complex proximal humerus fractures in the elderly — patients older than about 70 years with 3–4 part, head-split or fracture-dislocation patterns.
- Failed rotator cuff repair with stiffness and pain.
- Revision total shoulder arthroplasty (TSA) with rotator cuff deficiency.
- Rheumatoid arthritis with cuff destruction. Expanding indications include tumour reconstruction of the proximal humerus, severe bone loss in the revision setting, complex instability in the elderly with cuff deficiency, and selected acute fractures (controversial in younger patients). The absolute requirement. A functioning deltoid with an intact axillary nerve. The deltoid is the sole motor in RSA — without it the arm will not elevate regardless of the implant. Examine deltoid bulk, active contraction and axillary nerve sensation pre-operatively in every patient. RSA or TSA? The cuff status decides:
Primary glenohumeral osteoarthritis with a functioning rotator cuff. The cuff is needed to centre the head and to power movement.
Cuff tear arthropathy, a massive irreparable tear with pseudoparalysis, or a cuff-deficient revision. The reversed geometry lets the deltoid work alone.
If the patient cannot actively elevate above 90 degrees, the cuff is deficient regardless of the radiograph — choose RSA.
Contraindications. Absolute: deltoid insufficiency (paralysis or prior deltoid detachment failure), axillary nerve palsy, active infection, and glenoid bone stock that cannot be reconstructed. Relative: age less than 60 (higher revision burden and glenoid loosening concerns), high-demand patients expecting a return to sport or heavy labour, prior radiation to the shoulder (deltoid and soft-tissue damage), Charcot arthropathy, and uncontrolled diabetes or immunosuppression. Pre-operative assessment. Clinically, document active elevation (pseudoparalysis is less than 90 degrees), the external rotation lag sign (infraspinatus), the Hornblower sign (teres minor), the belly-press test (subscapularis), and — critically — deltoid bulk, function and axillary nerve sensation. Image with plain X-rays (AP, axillary lateral, Y-view) to assess the acromiohumeral interval (less than 7 mm indicates superior escape and cuff deficiency), acetabularisation and glenoid morphology; a CT scan for glenoid version and bone stock (retroversion more than 20 degrees may need an augmented baseplate, and more than 30 percent bone loss may need a graft); and an MRI to confirm the cuff is irreparable (Goutallier fatty infiltration) and to judge deltoid quality. Counsel the patient honestly: pain relief is excellent, forward elevation reaches about 120–140 degrees, but external rotation is often limited to neutral, scapular notching is common (50–80 percent), and 10–15 year implant survival is around 90–95 percent.
Do not use RSA for primary osteoarthritis with an intact cuff — TSA is indicated, and RSA carries a higher complication rate. Never proceed without examining the deltoid, because a subtle axillary nerve palsy will cause the operation to fail. RSA is not for the young high-demand patient expecting a return to heavy sport, and pseudoparalysis (active elevation less than 90 degrees) means cuff deficiency regardless of the X-ray.
The Operation
The goal is to resurface the glenoid with a glenosphere and the humerus with a concave polyethylene, medialising and distalising the centre of rotation so the deltoid can elevate the arm without a cuff. Everything hinges on exposure of the inferior glenoid and baseplate position. The steps below follow the deltopectoral approach, which is laid out in depth on the deltopectoral approach to the shoulder page.
Operative sequence
- Beach chair at 70–80 degrees — more upright than for TSA, because glenoid access (especially the inferior glenoid) is critical.
- Head secured in a horseshoe headrest; place a large bump under the medial scapular border to roll the scapula forward and bring the glenoid face anteriorly.
- Arm draped completely free to the fingertips so it can be manipulated; fluoroscopy available to confirm baseplate position.
- Mark the coracoid (the key landmark, palpated at every step), clavicle, acromion, AC joint and scapular spine.
- A 15–18 cm curvilinear incision from the coracoid distally toward the deltoid insertion — longer than for TSA because glenoid access is more demanding.
- Identify the deltopectoral groove and cephalic vein. Most surgeons retract the vein laterally with the deltoid (it has more tributaries on the deltoid side); the key is consistency. If it tears, ligate both ends and continue.
- Develop the interval proximally to the clavicle and distally 8–10 cm. This is a true internervous plane: deltoid (axillary nerve) lateral, pectoralis major (medial and lateral pectoral nerves) medial.
- Identify the conjoint tendon medially. The musculocutaneous nerve enters the conjoint tendon 5–8 cm distal to the coracoid (mean 5.5 cm) — keep the medial retractor within 5 cm of the coracoid and avoid distal medial dissection.
- Release the upper pectoralis major insertion if needed, staying on bone to protect the anterior circumflex vessels.
- Identify subscapularis — in cuff tear arthropathy it is often absent or severely atrophic; if present it may be released without repair, because RSA does not depend on it.
- Protect the deltoid absolutely — it is the motor for RSA, so avoid excessive lateral retraction.
- Perform an aggressive 360-degree capsular release — more extensive than in TSA: superior (excise the cuff remnant), anterior (with subscapularis), posterior, and inferior.
- The inferior release is the dangerous step. The axillary nerve runs with the posterior circumflex humeral artery on the anterior-inferior capsule, 5–7 cm below the acromion. Perform this release under direct vision, never blindly.
- Externally rotate, extend and adduct to deliver the humeral head.
- Make the humeral neck cut at the anatomic neck. The cut inclination matches the implant neck-shaft angle: the original Grammont/Delta uses a steeply valgus 155-degree inlay cup, while most modern systems use a 135–145-degree onlay or inlay design that lowers the humerus less and reduces adduction notching. Set the cut to the chosen system — do not free-hand a 155-degree cut into a 145-degree system.
- Place three retractors: anterior over the anterior rim, posterior into the capsule, and an inferior retractor into the axillary recess (protecting the axillary nerve).
- Expose the entire glenoid face including the inferior border — remove all labrum, capsule and osteophytes. If the inferior glenoid is not clearly seen, the baseplate cannot be placed correctly.
- The baseplate must sit flush with the inferior glenoid rim with 5–10 degrees of inferior tilt, in neutral version (0–5 degrees), and centred (not superior).
- Place the central guide pin aiming toward the coracoid base; confirm the position with fluoroscopy. Ream the glenoid face flat to bleeding bone.
- Insert the baseplate with central fixation (press-fit or screw), then 2–4 peripheral locking screws, all aiming for bicortical purchase (28–40 mm).
- Superior screw toward the coracoid base (strongest bone); inferior screw parallel to the face or slightly inferior; posterior screw at the scapular body anterior to the suprascapular notch (the nerve runs in the notch); anterior screw in a safe direction.
- Insert the glenosphere — typically 36 or 38 mm (larger means more stability and less notching); standard, lateralised or inferior-eccentric designs modify notching and range of motion.
- Open the canal with a box chisel in the centre of the metaphysis, then sequential broaching to metaphyseal contact.
- Set humeral retroversion at 0–20 degrees — less than TSA's 20–30 degrees — to optimise external rotation, which is limited in these patients.
- Insert the trial stem and polyethylene liner (typically 6, 9 or 12 mm) and reduce.
- Test stability: the commonest RSA instability is inferior — hold the arm adducted and apply an inferior distraction force; if it subluxes, use a thicker liner. Forward elevation should exceed 90 degrees (aim for 120–140 degrees); external rotation is often limited.
- Insert the final stem (cemented for poor bone, a wide canal, a metaphyseal defect or a periprosthetic fracture; otherwise an uncemented metaphyseal-engaging stem) and the matched liner, and reduce.
- If subscapularis was present and released, repair is optional in RSA (unlike TSA, where it is critical) — many surgeons do not repair, as function does not depend on it.
- Re-test all directions of stability (inferior, anterior, posterior) and document the range of motion achieved.
- Copious irrigation, meticulous haemostasis and a deep drain. Close the deltopectoral interval loosely (overtightening restricts the deltoid). Apply a sling with an abduction pillow at 30 degrees to prevent inferior instability.
The axillary nerve runs with the posterior circumflex humeral artery on the anterior-inferior capsule, 5–7 cm below the acromion. It is at risk during the inferior capsular release and inferior glenoid retractor placement. Release under direct vision, place the inferior retractor carefully, and avoid excessive traction. Injury paralyses the deltoid — and because the deltoid is the sole motor in RSA, the operation is essentially failed. Examine deltoid function and axillary nerve sensation before and after surgery; if there is no recovery by 6–12 months the prognosis is poor.
A superiorly-placed baseplate is the commonest cause of scapular notching (50–80 percent). If the inferior glenoid rim is not clearly exposed, take the time — complete the capsulectomy, reposition the scapular bump, and place the three retractors properly. The central guide pin should aim toward the coracoid base; confirm the inferior position with fluoroscopy before reaming.
On the anterior-inferior capsule, 5–7 cm below the acromion, with the posterior circumflex humeral artery. Injury is catastrophic — deltoid paralysis means RSA cannot function. Protect it during the inferior release and the inferior retractor, under direct vision.
Enters the conjoint tendon 5–8 cm distal to the coracoid (mean 5.5 cm). Injury causes biceps weakness and lateral forearm numbness. Keep the medial retractor within 5 cm of the coracoid; never retract the conjoint blindly.
Runs in the suprascapular notch, posterior to the glenoid. At risk from a posteriorly-directed baseplate screw. Aim the posterior screw at the scapular body, anterior to the notch.
Deep to the conjoint tendon, medial to the field. At risk from overzealous medial dissection or a deep medial retractor. Stay lateral to the conjoint, avoid deep medial dissection, and avoid excessive head tilt to prevent a traction injury.
About 90 percent of surgeons retract the cephalic vein laterally with the deltoid, because it has more tributaries on the deltoid side, keeping them under direct vision. The key is consistency — always retract the same way so you know where the vein is. If it tears, ligate both ends and continue; it is not critical.
In RSA the concave polyethylene sits on the convex glenosphere, and with the arm adducted the liner can ride off inferiorly — so the commonest dislocation direction is inferior (opposite to TSA, where posterior instability predominates). Test by adducting the arm and applying inferior distraction. Treat with a thicker liner; an abduction pillow post-operatively holds the arm out of the inferior subluxation position.
Aftercare & Complications
Rehabilitation | Phase | Timing | Immobilisation | Therapy | |-------|--------|-----------------|---------| | 1 | 0–6 weeks | Sling with abduction pillow (30 degrees) | Passive forward elevation to 120 degrees, external rotation to 20 degrees, pendulums; no active elevation | | 2 | 6–12 weeks | Wean the sling | Active-assisted then active ROM; begin deltoid strengthening | | 3 | 12 weeks plus | None | Unrestricted activities; advanced strengthening | Because RSA does not depend on subscapularis, passive forward elevation can begin immediately (unlike TSA). X-rays are taken at 6 weeks, 3 months, 1 year, then annually to monitor scapular notching and baseplate fixation. Expected outcome: excellent pain relief (90 percent or more), forward elevation of 120–140 degrees, external rotation often limited to neutral, and 90 percent or better satisfaction. Complications
- Recognition
- AP X-ray: erosion of the lateral scapular pillar below the glenosphere, Sirveaux grade 1–4; often asymptomatic
- Prevention
- Baseplate flush with the inferior glenoid, 5–10 degrees inferior tilt; larger (38 mm) glenosphere; lateralised designs
- Management
- Grade 1–2 observe; grade 3–4 with loosening needs complex revision (reposition, graft, lateralised design)
- Recognition
- Dislocation (usually inferior) or recurrent subluxation; X-rays show component position
- Prevention
- Appropriate liner thickness, avoid excessive glenoid anteversion, tension the soft tissues, test stability intra-operatively
- Management
- Closed reduction if acute; recurrent — CT the components, revise if malpositioned, thicker or constrained liner
- Recognition
- Deltoid weakness or paralysis, sensory loss over the lateral shoulder; catastrophic for RSA
- Prevention
- Inferior capsular release under direct vision; careful inferior retractor; avoid traction
- Management
- EMG at 6 weeks; most are neuropraxia — observe 6–12 months; if no recovery, RSA has failed
- Recognition
- Pain, erythema, discharge, fever, raised inflammatory markers; higher rate than TSA
- Prevention
- Prophylactic antibiotics; optimise diabetes, nutrition, smoking; avoid haematoma
- Management
- Acute (less than 6 weeks): washout, IV antibiotics, retain; chronic: two-stage revision
- Recognition
- New pain weeks to months post-op, tender over the acromion or spine; X-ray or CT confirms
- Prevention
- Largely unavoidable — altered biomechanics and increased deltoid tension; avoid over-lengthening
- Management
- Most heal with a sling for 6–12 weeks; non-union may need ORIF
- Recognition
- Intra-operative (during preparation or implantation) or post-operative (a fall)
- Prevention
- Careful technique in osteoporotic bone; avoid a varus entry; appropriate stem
- Management
- Intra-operative: cerclage, longer stem or ORIF; post-operative: revise with a longer stem if unstable
- Recognition
- Progressive pain and loss of function; radiolucency around the baseplate, often with advanced notching
- Prevention
- Bicortical screws, correct inferior position, augment bone defects
- Management
- Revision: remove the baseplate, graft the defects, larger or augmented baseplate
- Recognition
- Cannot reach behind the head; pre-existing from cuff deficiency
- Prevention
- Use less humeral retroversion (0–20 degrees); consider a latissimus dorsi transfer in selected cases
- Management
- Usually accepted; a latissimus dorsi or teres major transfer can add 20–30 degrees of ER
Viva & Exam Focus
REVERSEREVERSE — indications for RSA
GRAMMONTGRAMMONT — design principles
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 75-year-old woman has severe shoulder pain and cannot lift her arm above horizontal, for the past 2 years. The X-ray shows superior migration of the humeral head with acetabularisation of the acromion. What is your diagnosis and management?”
“What is scapular notching, why does it occur, and how do you prevent it?”
“Explain the Grammont design principles and how RSA biomechanics differ from the native shoulder and from TSA.”
Indications (cuff deficiency)
- Cuff tear arthropathy (Hamada 4–5) — the commonest indication
- Massive irreparable cuff tear with pseudoparalysis (elevation less than 90 degrees)
- Proximal humerus fractures in the elderly (older than 70 years, 3–4 part)
- Revision TSA with cuff deficiency
- Absolute requirement: a functioning deltoid plus an intact axillary nerve
Grammont principles
- Medialised centre of rotation — deltoid moment arm up 30–40 percent
- Distalised humerus — tensions the deltoid by 2–3 cm
- Fixed fulcrum at the glenosphere — the deltoid acts as an efficient lever
- The deltoid is the sole motor — the cuff is not required
- Inversion of the articulation (ball on the socket side) gives inherent stability
Key technical points
- Baseplate flush with the inferior glenoid, 5–10 degrees of inferior tilt
- The central pin aims at the coracoid base (confirm with fluoroscopy)
- Humeral version 0–20 degrees (less than TSA's 20–30 degrees)
- Subscapularis repair is optional (unlike TSA, where it is critical)
- Test inferior stability — the commonest instability direction
Danger structures
- Axillary nerve: 5–7 cm below the acromion on the anterior-inferior capsule — catastrophic if injured
- Musculocutaneous nerve: enters the conjoint tendon 5–8 cm distal to the coracoid
- Suprascapular nerve: posterior to the glenoid — posterior screw risk
- Posterior circumflex humeral artery: travels with the axillary nerve
Scapular notching prevention
- Occurs in 50–80 percent — the most important complication to prevent
- Primary cause: a superior baseplate position
- Prevention: baseplate flush inferior with 5–10 degrees of inferior tilt
- A larger glenosphere (38 mm) and lateralised designs reduce the risk
- Sirveaux grade 1–4 (grade 4 lies under the baseplate)
RSA versus TSA
- RSA: cuff deficient; TSA: cuff intact
- RSA: inferior instability; TSA: posterior instability
- RSA: subscapularis optional; TSA: subscapularis critical
- RSA: humeral version 0–20 degrees; TSA: 20–30 degrees
- RSA: abduction pillow; TSA: simple sling
Expected outcomes
- Pain relief: excellent (90 percent or more)
- Forward elevation: 120–140 degrees typical
- External rotation: limited (neutral to 20 degrees) — counsel the patient
- 10-year survival: about 90 percent (AOANJRR, NJR, AJRR data)
- Complications: notching 50–80 percent, instability 2–5 percent, infection 2–4 percent
Examiner favourites
- Why RSA works without a cuff — the Grammont mechanism (medialised centre of rotation, deltoid moment arm)
- Why baseplate position is critical — it prevents scapular notching
- Why axillary nerve injury is catastrophic — the deltoid is the sole motor
- RSA versus TSA indications — cuff status decides
- How to test stability — inferior distraction with the arm adducted
Background & Evidence
Design rationale. Paul Grammont developed reverse shoulder arthroplasty in the 1980s around a single idea — make the deltoid able to elevate the arm without a rotator cuff. Two design changes deliver this. First, the centre of rotation is medialised to the glenoid face, which increases the deltoid moment arm by 30–40 percent and recruits more deltoid fibres as abductors. Second, the humerus is distalised, which restores deltoid tension (by about 2–3 cm). A large glenosphere with no neck and a non-anatomic (originally 155-degree) humeral cup medialise and stabilise the centre of rotation and minimise torque on the glenoid. The convex glenosphere on the glenoid and the concave polyethylene on the humerus invert the articulation and provide a fixed, conforming fulcrum that prevents the superior escape seen in a failed TSA. The trade-offs follow directly from the geometry: external rotation is limited (the external rotators are deficient and the fulcrum is medialised) and the medialised centre brings the polyethylene close to the scapular pillar in adduction, causing scapular notching. Modern lateralised designs (bony-increased-offset RSA, 135-degree stems) restore some lateral offset to reduce notching and improve external rotation.
- Native shoulder
- Humeral head (lateral)
- TSA
- Humeral head
- RSA
- Glenoid face (medial)
- Native shoulder
- Essential
- TSA
- Essential
- RSA
- Not required
- Native shoulder
- Supraspinatus and deltoid
- TSA
- Supraspinatus and deltoid
- RSA
- Deltoid alone
- Native shoulder
- Dynamic (cuff)
- TSA
- Dynamic (cuff)
- RSA
- Static (conforming)
- Native shoulder
- Standard
- TSA
- Standard
- RSA
- Increased 30–40 percent
Scapular notching — the Sirveaux classification. Notching is mechanical impingement of the polyethylene on the lateral scapular pillar during adduction, visible on the AP X-ray as bone erosion below the glenosphere. It appears in 50–80 percent of RSA radiographs (many are asymptomatic grade 1–2). The dominant preventable cause is a superior baseplate position.
- Radiographic finding
- Small defect confined to the scapular pillar
- Significance
- Usually asymptomatic
- Radiographic finding
- Defect extends to the inferior screw
- Significance
- Usually observe
- Radiographic finding
- Defect extends over the inferior screw
- Significance
- Risk of progressive loosening
- Radiographic finding
- Defect extends under the baseplate
- Significance
- Loosening risk — may need revision
References
Grammont reverse prosthesis: design, rationale, and biomechanics
- Two innovations underpin the Grammont design: a large glenosphere with no neck and a non-anatomic 155° humeral cup covering less than half of the glenosphere
- Design medialises and stabilises the centre of rotation, minimises torque on the glenoid, and recruits more deltoid fibres as abductors; the humerus is lowered to restore deltoid tension
- Restores active elevation above 90° in cuff-deficient shoulders, but external rotation remains limited (especially with absent or fatty teres minor) and scapular notching is a concern
Grammont inverted total shoulder arthroplasty for glenohumeral OA with massive cuff tear (multicentre, 80 shoulders) - source of the notching classification
- 80 shoulders, mean follow-up 44 months: mean Constant score rose from 22.6 to 65.6; active forward elevation rose from 73° to 138°
- Integrity of teres minor was essential for recovery of external rotation and significantly influenced the Constant score
- Defined the scapular notching grading (Sirveaux Grade 1-4); recommended the prosthesis be reserved for elderly patients
Reverse total shoulder arthroplasty: survivorship analysis of eighty replacements followed for five to ten years
- Survival at 120 months was 91% with prosthesis replacement as the endpoint and 84% with glenoid loosening as the endpoint
- Cuff-tear arthropathy fared significantly better than other aetiologies (rheumatoid, trauma, revision)
- Two breaks in the survival curve: early loosening at around 3 years, then progressive functional deterioration from around 6 years
Reverse total shoulder arthroplasty: a review of results according to aetiology
- 240 RSAs (mean age 72.7 years): mean Constant score improved from 23 to 60; 173 of 186 patients satisfied or very satisfied
- Cuff-tear arthropathy, primary OA with cuff tear, and massive cuff tear had better outcomes than post-traumatic arthritis or revision
- Dislocation and infection were the most common complications; revision cases had higher complication rates than primaries
The Reverse Shoulder Prosthesis for glenohumeral arthritis with severe rotator cuff deficiency (minimum two-year follow-up, 60 patients)
- 60 patients (mean age 71): mean ASES score improved from 34.3 to 68.2; forward flexion improved from 55° to 105° and abduction from 41° to 102°
- 13 complications in 10 patients (17%); 7 patients (12%) had failures requiring revision
- Used a lateralised (Frankle) glenoid design rather than the medialised Grammont design
Delta shoulder prosthesis for rotator cuff rupture — the original description
The original description of the Delta Mark III reverse prosthesis for rotator cuff rupture — the design that established the medialised centre of rotation principle on which all modern RSA systems build.
Problems, complications, reoperations and revisions in reverse total shoulder arthroplasty — systematic review
Systematic review quantifying the complication and revision burden of RSA — the basis for the overall complication rates quoted in patient counselling.
Effect of humeral stem design on humeral position and range of motion in reverse shoulder arthroplasty
Underpins the humeral neck-shaft angle (135–145 degree modern designs versus the 155 degree Grammont) and version considerations that influence range of motion and notching.
A history of reverse total shoulder arthroplasty
Historical review of the development of RSA, from early failed designs to the successful Grammont concept.
National joint registry shoulder arthroplasty data (AOANJRR, UK NJR, AJRR)
Registry implant survivorship and revision benchmarks for reverse shoulder arthroplasty — the basis for the quoted 10-year survival and revision rates across aetiologies.