Shoulder Instability — Revision Surgery

Recurrent shoulder instability following failed primary stabilisation surgery is a clinically challenging problem requiring systematic analysis of the cause of failure before embarking on revision. The most common reason for failure of a primary Bankart repair is unrecognised or inadequately addressed bone loss — either glenoid, humeral, or both. Revision instability surgery demands a thorough understanding of the engaging Hill-Sachs lesion, glenoid track concept, and when to escalate from soft tissue to bony procedures.

• Recurrence after primary arthroscopic Bankart repair: approximately 15–25% overall; significantly higher in patients with significant bone loss, hyperlaxity, young age (<20 years), competitive contact sport, and off-track Hill-Sachs lesions
• Recurrence after open Bankart repair: approximately 5–10% — lower than arthroscopic in the presence of bone loss
• Most common causes of failure: unrecognised glenoid bone loss (most common), engaging Hill-Sachs lesion (off-track), soft tissue failure (anchor pullout, capsule stretching), hyperlaxity not addressed, incorrect patient selection
• The critical step before any revision instability surgery is quantification of bone loss — CT scan with 3D reconstruction is mandatory; glenoid bone loss >20–25% and/or engaging off-track Hill-Sachs lesion requires a bony procedure rather than repeat soft tissue repair
• Latarjet procedure is now the most commonly performed revision procedure and the primary procedure in patients with significant bone loss

The glenoid track concept (Di Giacomo, 2014) provides a unified framework for assessing the interaction between glenoid bone loss and the Hill-Sachs lesion, and predicting engagement risk.

• Glenoid track: the zone of the humeral head that contacts the anterior glenoid rim during extreme abduction and external rotation (the position of apprehension and dislocation); calculated as a percentage of the glenoid width
• Glenoid track formula: GT = 0.83 × D − (d + HS width) where D = glenoid diameter, d = amount of anterior glenoid bone loss, HS = Hill-Sachs lesion width
• On-track Hill-Sachs: the medial extent of the Hill-Sachs lesion falls within the glenoid track — will NOT engage during movement; soft tissue repair (Bankart) appropriate
• Off-track Hill-Sachs: the medial extent of the Hill-Sachs lesion extends beyond the glenoid track — WILL engage the anterior glenoid rim during ABER; soft tissue repair alone will fail; requires bony procedure (Latarjet or remplissage)
• Glenoid bone loss quantification: CT 3D en-face (best-fit circle method); <13.5% = low risk; 13.5–20% = moderate risk; >20–25% = high risk; absolute threshold for Latarjet is debated — most use >20–25% as the cutoff

The Latarjet procedure transfers the coracoid process with its attached conjoint tendon to the anterior glenoid rim, providing three simultaneous stabilising mechanisms — the "triple-block effect."

• Triple-block mechanism:

• Latarjet indications: glenoid bone loss >20–25%; off-track Hill-Sachs; failed previous Bankart repair (especially with bone loss); contact sport athletes at high risk of recurrence; hyperlaxity with bone loss; revision instability
• Coracoid graft positioning: flush with or slightly proud of the anterior glenoid surface — proud graft risks humeral head erosion and OA; recessed graft loses bony block effect; the inferior coracoid surface should be flush with the glenoid face
• Fixation: two divergent screws (3.5 mm or 4.5 mm cortical) through the coracoid into the glenoid neck; parallel placement risks coracoid fracture; convergent placement risks screw loosening
• Subscapularis management: split (Latarjet) through the lower 1/3 and upper 2/3 — preserves subscapularis function; divide (Bristow variant) — less commonly used
• Arthroscopic Latarjet: increasingly performed; equivalent results to open in experienced hands; technically demanding; steep learning curve; not recommended without significant experience
• Results: recurrence rate approximately 2–5%; 10-year survivorship approximately 94–95%; patient satisfaction high; return to sport approximately 75–85%

• Remplissage: arthroscopic posterior capsulodesis and infraspinatus tenodesis into the Hill-Sachs defect — fills the defect, preventing it from engaging the anterior glenoid rim
• Remplissage indication: off-track Hill-Sachs lesion with minimal or no significant glenoid bone loss (<20%); converts an engaging Hill-Sachs to a non-engaging one; performed concurrently with arthroscopic Bankart repair
• The soft tissue fill prevents engagement but does not restore bone — appropriate only when Hill-Sachs is the primary problem without significant glenoid bone loss
• Functional consequence: approximately 10–15° loss of external rotation post-remplissage — acceptable trade-off in most patients; affects overhead athletes disproportionately
• Results: re-dislocation rate approximately 5–8%; lower than Bankart alone for off-track lesions; external rotation loss is the main reported limitation
• Remplissage vs Latarjet for off-track Hill-Sachs with minimal glenoid loss: no definitive superiority established; Latarjet preferred by many when glenoid loss approaching 20%; remplissage preferred when glenoid loss is minimal (<13%) and Hill-Sachs is the dominant problem

• Revision after failed Latarjet is among the most challenging procedures in shoulder surgery — anatomy is distorted, bone is scarce, and neurovascular structures are at risk
• Options for massive glenoid bone loss after failed Latarjet:
• Iliac crest bone graft (ICBG): structural graft for large glenoid defects; tricortical ICBG shaped to restore glenoid arc; fixed with screws; used when coracoid graft has resorbed or is inadequate; lower long-term results than primary Latarjet
• Distal tibia allograft: increasingly popular — anatomical congruity with glenoid curve; fresh frozen allograft; no donor site morbidity; good early results; less evidence than ICBG
• Glenohumeral arthrodesis: salvage for failed multiple instability procedures with severe bone loss and/or poor soft tissue — fuses shoulder in functional position; reliable pain relief but significant functional limitation
• Reverse shoulder arthroplasty: for older patients with failed instability surgery, severe arthritis, and cuff deficiency — addresses arthritis and instability simultaneously in appropriate patients

• The ISIS score (Instability Severity Index Score): pre-operative scoring system (0–10) for predicting recurrence after arthroscopic Bankart repair; factors include age, sport level, contact sport, hyperlaxity, Hill-Sachs on AP X-ray, and glenoid bone loss on face view X-ray; score >6 predicts 70% recurrence after arthroscopic Bankart — Latarjet recommended instead
• Posterior instability: accounts for approximately 5% of recurrent shoulder instability; causes include posterior labral tear (Kim lesion), posterior bone loss, excessive glenoid retroversion, and posterior capsular laxity; management with arthroscopic posterior labral repair ± posterior bone block (posterior iliac crest graft) for significant posterior glenoid bone loss
• Multidirectional instability (MDI): generalised glenohumeral laxity without a discrete labral tear; associated with hyperlaxity syndromes (Ehlers-Danlos, Marfan); primary treatment is rehabilitation (rotator cuff strengthening programme — Rockwood exercise programme); surgery (inferior capsular shift) only after 6–12 months of intensive rehabilitation failure; avoid Latarjet in MDI without bone loss — does not address the underlying capsular laxity
• Latarjet graft positioning pearls: the bone graft must be placed flush with the glenoid articular surface (not proud, not recessed); assess on intraoperative fluoroscopy or arthroscopy; the inferior edge of the coracoid should be at the inferior glenoid level; the conjoint tendon should pass under the subscapularis split to provide the sling effect

• Most common cause of failed Bankart repair: unrecognised glenoid bone loss; always CT 3D before revision
• Glenoid bone loss >20–25%: Latarjet; off-track Hill-Sachs: Latarjet or remplissage
• Glenoid track: on-track = safe for Bankart; off-track = engaging Hill-Sachs = bony procedure required
• Latarjet triple block: bony extension of glenoid + conjoint tendon sling + capsular repair
• Proud coracoid graft: humeral head erosion → osteoarthritis; flush is correct position
• Musculocutaneous nerve: enters conjoint tendon 3–5 cm distal to coracoid; most feared neurological complication of Latarjet
• Remplissage: fills Hill-Sachs with capsule/infraspinatus; off-track lesion + minimal glenoid loss (<20%); 10–15° ER loss
• ISIS score >6: 70% recurrence with arthroscopic Bankart → perform Latarjet instead
• MDI: rehabilitation first (6–12 months); inferior capsular shift only after failure; NOT Latarjet
• Failed Latarjet with massive bone loss: iliac crest bone graft or distal tibia allograft; glenohumeral arthrodesis as salvage