Subscapularis Management in Shoulder Arthroplasty

What it is. Subscapularis management in shoulder arthroplasty is the controlled detachment and repair of the subscapularis tendon from the lesser tuberosity during anatomic glenohumeral arthroplasty through the deltopectoral approach. The subscapularis arises from the subscapular fossa of the scapula, crosses the anterior glenohumeral joint, and inserts on the lesser tuberosity; the bicipital groove separates this insertion from the greater-tuberosity insertions of supraspinatus, infraspinatus and teres minor. The tendon must be taken down to enter the joint and deliver the humeral head, and the chosen takedown-and-repair technique directly governs postoperative internal-rotation strength, the belly-press and lift-off examination, and anterior stability. Three established techniques exist: tenotomy, subscapularis peel and lesser-tuberosity osteotomy. Indications. - Anatomic total shoulder arthroplasty for glenohumeral osteoarthritis with an intact, repairable rotator cuff

• Shoulder hemiarthroplasty for arthritis or avascular necrosis when the glenoid is preserved
• Selected proximal humeral fractures managed through the deltopectoral approach (the tuberosity is already fractured, so a separate osteotomy is not performed)
• Revision shoulder arthroplasty requiring re-exposure of the glenohumeral joint Contraindications to anatomic arthroplasty (a different strategy is needed): - Irreparable massive rotator cuff tear with cuff-tear arthropathy - reverse total shoulder arthroplasty is preferred, and a deficient subscapularis cannot be managed in the standard way
• Severe subscapularis fatty infiltration or tear at the index operation - peel or osteotomy may not be feasible
• Active infection Alternative exposure. The anterosuperior (deltoid-on) approach is used by some surgeons for anatomic arthroplasty and leaves the subscapularis largely undisturbed, but the deltopectoral approach remains the workhorse exposure taught in examinations and is the focus of this page.

Comparing the three techniques. The three options differ in how the tendon is separated from bone and, crucially, in the healing interface they create.

Healing hierarchy. Reliability follows a clear order: bone-to-bone (osteotomy) is stronger than tendon-to-bone (peel), which is stronger than tendon-to-tendon (tenotomy). This single fact is the rationale for choosing a peel or an osteotomy over a simple tenotomy, and it is the most commonly asked viva point on the topic. How to choose. A peel or lesser-tuberosity osteotomy is preferred when subscapularis integrity is critical - typically a younger, higher-demand patient - because of superior healing. A tenotomy remains acceptable in lower-demand patients and is the simplest and fastest option; Z-lengthening is added to a tenotomy only when the subscapularis is tight and limits external rotation. An osteotomy is avoided in fracture arthroplasty, where the tuberosity is already fractured and should be repaired directly. A deficient or irreparable subscapularis shifts the decision toward a reverse total shoulder arthroplasty rather than an anatomic design.

Work down through the deltopectoral interval, protect the axillary nerve at the inferior border, take the subscapularis down by the chosen technique, deliver and prepare the joint, then repair the tendon with a construct matched to the takedown and close loosely.

Structures at risk, by layer

Extensile options. Extend proximally along the groove toward the coracoid and clavicle to reach the rotator interval, the coracoid, the conjoined tendon and the acromioclavicular joint (useful for combined rotator-cuff repair or coracoplasty). Extend distally along the humeral shaft toward the deltoid insertion to reach the proximal humeral diaphysis (rarely needed for arthroplasty, but useful in fracture or revision with stem extension). The posterior cuff and posterior glenoid are not addressed by this approach alone and may require adjunct windows or repositioning in complex revisions. Postoperative protection of the repair (approximately 6 weeks). - Sling or shoulder immobiliser, with the arm in neutral to slight external rotation

• Passive and active-assisted forward flexion as prescribed, with pendulums
• Limit passive external rotation beyond the safe intra-operative range
• Avoid active internal rotation against resistance (for example, pushing up from a chair) for 6 weeks Rehabilitation phases. - Phase 1 (0 to 6 weeks): protection and passive or active-assisted motion; pendulums; no resisted internal rotation
• Phase 2 (6 to 12 weeks): progressive active motion and gentle strengthening; restore rotation
• Phase 3 (3 months and beyond): progressive resistance and return to function Complications | Complication | Prevention | Management | |--------------|------------|------------| | Subscapularis failure / anterior instability | Sound repair, correct tension and version, 6-week protection | Bracing; revision repair; pectoralis major transfer for chronic insufficiency | | Axillary nerve injury | Stay on bone, palpate the nerve, no blind inferior retractors | Observe for neurapraxia; explore if no recovery; rehabilitation | | Musculocutaneous nerve injury | Gentle medial retraction of the conjoined tendon | Observe; most recover; rehabilitation | | Stiffness | Early controlled motion within limits | Physiotherapy; manipulation under anaesthesia or release if persistent | | Infection | Aseptic technique, prophylactic antibiotics | Irrigation and debridement; component retention or revision as indicated | | Osteotomy nonunion or migration (LTO) | Precise technique, secure cerclage | Revision fixation if symptomatic |

• Anatomic total shoulder arthroplasty - the principal operation done through this exposure
• Shoulder hemiarthroplasty for arthritis or avascular necrosis with the glenoid preserved
• Selected proximal humeral fracture fixation or arthroplasty (the tuberosity is already fractured, so no separate osteotomy)
• Revision shoulder arthroplasty - re-exposure of the glenohumeral joint
• Not addressed by this approach alone: the posterior cuff and posterior glenoid (may require adjunct windows or repositioning in complex revisions)

During anatomic shoulder arthroplasty through the deltopectoral approach, the subscapularis must be taken down from the lesser tuberosity to enter the glenohumeral joint, and the chosen repair governs postoperative internal-rotation strength, the belly-press examination and anterior stability. Three established techniques exist. Tenotomy cuts the tendon and repairs it tendon-to-tendon or tendon-to-bone; it is simple but has the weakest healing. A subscapularis peel elevates the tendon off its footprint and repairs it tendon-to-bone with anchors or transosseous tunnels. A lesser-tuberosity osteotomy (Gerber) raises bone with the tendon and fixes it with cerclage, healing bone-to-bone - the strongest interface. The healing hierarchy is bone-to-bone stronger than tendon-to-bone stronger than tendon-to-tendon. The axillary nerve at the inferior border of the subscapularis is the critical at-risk structure and is protected by staying on bone and avoiding blind inferior retractors.

Guidelines, Registries & Global Practice

Management of the subscapularis in anatomic shoulder arthroplasty is governed by surgical-biomechanical principles that converge across examination systems. The deltopectoral approach, protection of the axillary nerve at the inferior border, and the healing hierarchy (bone-to-bone stronger than tendon-to-bone stronger than tendon-to-tendon) are universally taught. Arthroplasty registry evidence (for example the National Joint Registry and the Australian Orthopaedic Association National Joint Replacement Registry) principally reports survivorship and revision rather than subscapularis-specific technique, but revision for instability is captured and is relevant to subscapularis failure. Side-by-side principles (where guidance converges): | Body | Position on subscapularis management | |------|--------------------------------------| | AAOS (US) | Secure subscapularis repair and protection are essential to anterior stability after anatomic arthroplasty; technique is surgeon-dependent but bone-to-bone/tendon-to-bone constructs are favoured for higher-demand patients | | BESS / BOA / EFORT | The deltopectoral approach is standard; the axillary nerve at the inferior border must be protected; lesser-tuberosity osteotomy or peel preferred when subscapularis integrity is critical | | AO Foundation | Restoration of soft-tissue tension and version is part of balanced arthroplasty; protect the repair and limit early external rotation and resisted internal rotation | Registry / population evidence: - Arthroplasty registries report shoulder arthroplasty revision rates broadly in the single-digit percent range at mid-term follow-up, with instability a recognised mode of failure after anatomic designs

• Subscapularis failure is a contributor to instability-related revision, which underlines the preventive value of a sound repair Global practice variation. In well-resourced settings, suture anchors, anatomic implants and lesser-tuberosity osteotomy are widely available. In resource-limited settings, the same biomechanical principles are applied with transosseous bone tunnels and standard implants; a simple tenotomy with a meticulous repair remains a reasonable, lower-cost option. Consent (globally applicable). Discuss subscapularis dysfunction or failure with possible anterior instability, axillary nerve injury with deltoid weakness, stiffness, infection, and the potential need for revision (including pectoralis major transfer or conversion to a reverse design) if the subscapularis fails.