Glenohumeral Osteoarthritis: Etiology, Surgical Anatomy & Biomechanical Principles for Management

Shoulder Osteoarthritis: The Best Orthopedic Answers You Need

Introduction & Epidemiology

Glenohumeral osteoarthritis (GHOA) represents a degenerative arthropathy characterized by progressive articular cartilage loss, subchondral bone remodeling, osteophyte formation, and capsular contracture. It is a significant cause of shoulder pain and dysfunction, profoundly impacting patient quality of life.

GHOA can be classified as primary (idiopathic) or secondary. Primary GHOA typically affects individuals over 50 years of age, with a gradual onset of symptoms. Secondary GHOA, conversely, is attributable to identifiable underlying etiologies, including:
* Post-traumatic arthritis: Following fractures of the proximal humerus or glenoid, dislocations, or chronic instability.
* Rotator cuff arthropathy (Cuff Tear Arthropathy, CTA): Chronic, massive, irreparable rotator cuff tears leading to superior humeral head migration, glenoid erosion, and incongruity.
* Inflammatory arthropathies: Rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis.
* Osteonecrosis: Avascular necrosis of the humeral head.
* Dysplasia: Glenoid or humeral head dysplastic conditions.
* Infection: Septic arthritis.
* Metabolic disorders: Gout, pseudogout.

Epidemiologically, GHOA incidence increases with age. Radiographic evidence of GHOA is present in up to 30% of individuals over 60, though symptomatic prevalence is lower. Risk factors include advanced age, genetic predisposition, a history of shoulder trauma or surgery, certain occupations requiring repetitive overhead activity, and obesity. CTA is a distinct subset, accounting for a substantial proportion of end-stage shoulder arthritis, particularly in elderly populations. Understanding these etiological factors is crucial for accurate diagnosis, prognosis, and treatment planning.

Surgical Anatomy & Biomechanics

A thorough understanding of the surgical anatomy and biomechanics of the glenohumeral joint is paramount for effective management of GHOA, particularly in arthroplasty.

Glenohumeral Joint Articulation

The glenohumeral joint is a multiaxial diarthrodial ball-and-socket joint, providing the greatest range of motion of any joint in the body at the expense of inherent stability.
* Humeral Head: Approximately one-third of a sphere, oriented posteromedially and superiorly relative to the humeral shaft. Its articular surface is covered by hyaline cartilage.
* Glenoid Fossa: A shallow, pear-shaped articular surface of the scapula, significantly smaller than the humeral head (articulating surface ratio is approximately 1:4). The glenoid is typically retroverted by 0-10 degrees and superiorly inclined by 5-10 degrees. The glenoid labrum, a fibrocartilaginous ring, deepens the socket and provides attachment for the glenohumeral ligaments.
* Articular Cartilage: In GHOA, the articular cartilage undergoes progressive degeneration, characterized by fibrillation, fissuring, erosion, and ultimately complete loss, exposing subchondral bone. This process alters the joint congruity and load distribution.

Stabilizers of the Glenohumeral Joint

• Static Stabilizers:
  • Capsule and Glenohumeral Ligaments (GHLs): Superior, middle, and inferior GHLs (anterior and posterior bands) reinforce the anterior capsule, providing primary stability against translation and external rotation.
  • Glenoid Labrum: Enhances glenoid depth and serves as an attachment site for the GHLs and biceps tendon.
  • Negative Intra-articular Pressure: Contributes to joint stability.
• Dynamic Stabilizers:
  • Rotator Cuff Muscles: Supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles depress and center the humeral head within the glenoid fossa during deltoid contraction, providing dynamic stability and facilitating smooth joint kinematics.
  • Long Head of Biceps Tendon: Contributes to anterior stability and humeral head depression.
  • Deltoid Muscle: The primary abductor and flexor of the shoulder. Its integrity is critical, particularly in the context of reverse total shoulder arthroplasty (rTSA).

Neurovascular Structures

• Axillary Nerve: Courses inferior to the humeral head, supplying the deltoid and teres minor. It is vulnerable during inferior capsular release, humeral head dislocation, and humeral reaming.
• Musculocutaneous Nerve: Pierces the coracobrachialis, supplying the coracobrachialis, biceps, and brachialis.
• Suprascapular Nerve: Courses through the suprascapular notch, supplying the supraspinatus and infraspinatus. Vulnerable during excessive retraction of the supraspinatus or in posterior glenoid exposure.
• Brachial Plexus: Located superior and medial to the joint, susceptible to traction injury.
• Vascular Structures: Anterior and posterior circumflex humeral arteries, branches of the axillary artery, supply the humeral head and surrounding soft tissues. The anterior circumflex humeral artery gives rise to the arcuate artery, a major blood supply to the humeral head, vulnerable during anterior approaches.

Biomechanical Considerations in GHOA and Arthroplasty

• Joint Center of Rotation (COR): In a healthy shoulder, the COR is located centrally within the glenoid. In OA, articular erosion, osteophyte formation, and rotator cuff deficiency can lead to superior, posterior, or eccentric migration of the humeral head, altering the COR.
• Conventional Total Shoulder Arthroplasty (TSA): Aims to restore the native anatomy and COR, relying on an intact and functional rotator cuff for dynamic stability and optimal function. Appropriate glenoid component version and inclination, along with humeral component retroversion and offset, are critical for stability and range of motion.
• Reverse Total Shoulder Arthroplasty (rTSA): Medializes and distalizes the COR by inverting the ball-and-socket anatomy (glenosphere on glenoid, humeral cup on humerus). This design converts the deltoid into a more efficient abductor, compensating for deficient rotator cuff function. However, this altered biomechanics places increased stress on the deltoid and periscapular musculature, and changes the relationship between the acromion and humerus. Careful attention to glenosphere lateralization, humeral offset, and deltoid tension is essential to optimize outcomes and minimize complications such as impingement and scapular notching.

Indications & Contraindications

The decision-making process for surgical intervention in GHOA is complex, weighing patient factors, disease severity, failed conservative management, and the specific etiology of arthritis.

Non-Operative Indications

Non-operative management is the initial approach for nearly all patients with GHOA, particularly those with mild to moderate symptoms, early-stage disease, or significant surgical contraindications.
* Mild to moderate pain: Successfully managed with analgesia.
* Preserved functional range of motion: Adequate for activities of daily living (ADLs).
* Patient preference: Unwillingness to undergo surgery.
* Significant medical comorbidities: Increased surgical risk.
* Early-stage GHOA: Without significant radiographic changes or cartilage loss.
* Failure of conservative measures not yet reached: Including activity modification, physical therapy, NSAIDs, corticosteroid injections, and potentially viscosupplementation.

Operative Indications

Surgical intervention is considered when non-operative measures fail to provide adequate pain relief or functional improvement, and the patient's quality of life is significantly compromised.

Specific Surgical Options:

• Arthroscopy (Diagnostic/Debridement):
  • Indications: Often limited, primarily for early GHOA with mechanical symptoms (e.g., loose bodies, osteophyte impingement, capsular contracture without significant cartilage loss). Can be used for debridement, capsular release, synovectomy, or biceps tenodesis. Rarely a definitive long-term solution for advanced GHOA.
  • Contraindications: Significant cartilage loss, advanced radiographic changes, inflammatory arthropathy with widespread synovitis.
• Glenohumeral Hemiarthroplasty (HA):
  • Indications: Avascular necrosis of the humeral head with a preserved glenoid, severe humeral head destruction (e.g., complex proximal humerus fracture with concomitant arthritis) in younger, active patients where glenoid resurfacing might not be durable. Patients with glenoid cartilage softening but not erosion.
  • Contraindications: Significant glenoid erosion or cartilage loss (risk of pain from glenoid wear), inflammatory arthritis, irreparable rotator cuff tears (leading to superior migration).
• Total Shoulder Arthroplasty (TSA):
  • Indications: Primary GHOA with intact and functional rotator cuff tendons, post-traumatic arthritis with intact rotator cuff, inflammatory arthritis (e.g., rheumatoid arthritis) with intact rotator cuff. Patients must have adequate glenoid bone stock for component fixation.
  • Contraindications: Irreparable rotator cuff tear (relative, as pain may persist or develop, leading to early failure), active infection, severe deltoid dysfunction, significant glenoid bone loss that precludes stable glenoid component fixation.
• Reverse Total Shoulder Arthroplasty (rTSA):
  • Indications: Rotator cuff arthropathy (CTA) – the primary indication. Failed TSA with rotator cuff deficiency. Proximal humerus fractures in elderly patients with poor bone quality or significant comminution where osteosynthesis is challenging. Tumour resection. Revision surgery for failed conventional arthroplasty with cuff deficiency. Massive, irreparable rotator cuff tears without arthritis but significant pseudoparalysis.
  • Contraindications: Active infection, deltoid paralysis or significant dysfunction (the deltoid is the primary motor for rTSA), insufficient glenoid bone stock for stable baseplate fixation (though glenoid reconstruction techniques exist), unmanaged brachial plexus injury.

General Contraindications for Shoulder Arthroplasty:

• Active infection (local or systemic).
• Uncontrolled medical comorbidities (e.g., severe cardiac, pulmonary, or renal disease) that significantly elevate surgical risk.
• Progressive neurologic disease affecting the shoulder or upper extremity.
• Poor patient compliance with rehabilitation protocols.
• Significant soft tissue compromise at the surgical site.
• Charcot arthropathy.

TABLE: Operative vs. Non-Operative Indications for Glenohumeral Osteoarthritis

Pre-Operative Planning & Patient Positioning

Meticulous pre-operative planning is critical to optimizing outcomes, minimizing complications, and ensuring efficient surgical execution in shoulder arthroplasty.

Pre-Operative Assessment:

1. History: Detailed pain history (location, character, exacerbating/alleviating factors), functional limitations, previous shoulder injuries/surgeries, medical comorbidities, medications (especially anticoagulants, steroids), smoking/alcohol history, patient expectations.
2. Physical Examination:
   • Inspection: Atrophy (deltoid, rotator cuff), scars, asymmetry.
   • Palpation: Tenderness (AC joint, biceps groove, glenohumeral joint line).
   • Range of Motion (ROM): Active and passive ROM in all planes (flexion, extension, abduction, adduction, internal/external rotation). Differentiate true capsular stiffness from pain-limited motion.
   • Strength: Manual muscle testing of rotator cuff, deltoid, periscapular muscles. Assess for pseudoparalysis in suspected CTA.
   • Neurovascular Status: Sensation, motor function (axillary, musculocutaneous, radial, ulnar, median nerves), pulses.
   • Special Tests: Though often limited by pain in advanced OA, they can provide adjunctive information.
3. Imaging:
   • Plain Radiographs: Standard series includes true AP (Grashey), scapular Y-view, and axillary lateral views. Essential for assessing joint space narrowing, osteophytes, subchondral sclerosis/cysts, humeral head migration/flattening, glenoid erosion (central vs. eccentric, superior vs. posterior), and presence of prior hardware.
   • Computed Tomography (CT) Scan: The gold standard for assessing glenoid bone loss, version, and inclination. Crucial for templating the glenoid component, particularly in cases of significant erosion (Walch classification) or dysplastic glenoids. Three-dimensional reconstructions aid in surgical planning and identifying exact glenoid morphology.
   • Magnetic Resonance Imaging (MRI): Primary utility in evaluating rotator cuff integrity, particularly important for differentiating between TSA (intact cuff) and rTSA (cuff deficiency/arthropathy). Also assesses biceps pathology and other soft tissue lesions. May not be necessary if cuff status is clearly established clinically or by other means.
   • Arthrography: Rarely used now, but can confirm cuff tears.

Templating and Surgical Planning:

• Component Sizing: Based on pre-operative radiographs and CT.
  • Humeral Head: Size and offset matching for TSA/HA. For rTSA, stem length, diameter, and offset.
  • Glenoid Component: Size (to cover as much glenoid as possible without overhang), version, and inclination. CT templating helps determine the optimal placement of the glenoid baseplate for rTSA, considering bone quality and avoidance of impingement.
• Implant Type: Cemented vs. uncemented humeral stem, pegged vs. keeled glenoid (TSA), baseplate type (fixed angle vs. variable angle, lateralizing vs. medializing) and glenosphere size/offset (rTSA).
• Approach Selection: Predominantly deltopectoral for TSA/HA and often for rTSA.
• Contingency Planning: Plan for potential intraoperative challenges such as severe glenoid bone loss, difficulty with component removal in revisions, or intraoperative fractures. Availability of revision components.

Patient Positioning:

The most common position for shoulder arthroplasty is the Beach Chair Position .
* Setup:
* Patient supine on an operating table that can be flexed.
* Torso elevated to 30-70 degrees (surgeon preference).
* Head secured in a padded headrest, neutral alignment, ensuring no hyperextension or lateral flexion to prevent brachial plexus stretch.
* Affected shoulder positioned at the edge of the table to allow for full range of motion without impingement on the table.
* An arm holder (e.g., traction tower, bean bag with blanket roll) can support the ipsilateral arm during preparation and draping, allowing for manipulation during the procedure.
* The contralateral arm is tucked to the side, padded, and protected.
* Key Considerations:
* Airway Management: Secure endotracheal tube.
* Nerve Protection: Meticulous padding of all pressure points (ulnar nerves, common peroneal nerves, sacrum). Ensure no excessive traction on the brachial plexus, especially during arm manipulation.
* Hemodynamic Monitoring: The beach chair position can lead to significant drops in blood pressure due to gravitational pooling. Anesthetic management must account for this, often involving vasopressors and careful fluid administration. Continuous arterial line monitoring is common.
* Visualization: Ensures unhindered access to the anterior and superior aspects of the shoulder. Fluoroscopy can be easily positioned.
* Pneumatic Tourniquet: A tourniquet on the ipsilateral arm is often used for brief periods during cementation or to control bleeding for improved visualization, especially if blood pressure is higher.

The Lateral Decubitus Position is less commonly used for primary arthroplasty but can be considered, especially for revision cases or if significant posterior exposure is anticipated. It requires specific traction setups and careful patient stabilization.

Detailed Surgical Approach / Technique

This section will focus on the deltopectoral approach, which is the workhorse for both conventional (TSA/HA) and reverse total shoulder arthroplasty (rTSA).

1. Deltopectoral Approach for Total Shoulder Arthroplasty (TSA)

• Incision: A curvilinear incision approximately 8-10 cm long, beginning just lateral to the coracoid process, extending inferiorly along the deltopectoral groove towards the anterior axillary fold.
• Dissection to Deltopectoral Interval:
  • Identify the cephalic vein, which serves as a key landmark in the deltopectoral groove. It is typically retracted medially with the pectoralis major. Care must be taken to preserve it, though it can be ligated if necessary for exposure.
  • The internervous plane is between the deltoid (axillary nerve innervation, lateral) and the pectoralis major (medial and lateral pectoral nerve innervation, medial).
  • Deep to the cephalic vein, incise the clavipectoral fascia longitudinally.
• Exposure of Deep Structures:
  • Retract the deltoid laterally and the pectoralis major medially.
  • Identify the conjoint tendon (short head of biceps and coracobrachialis) and the coracoid process. These are retracted medially.
  • The subscapularis tendon lies anterior to the joint capsule, extending from the lesser tuberosity to the anterior glenoid rim. Protect the axillary nerve which lies inferiorly.
• Subscapularis Management:
  • Lesser Tuberosity Osteotomy: A common technique, involving an osteotomy of the lesser tuberosity with the subscapularis attached. This allows for excellent exposure and provides a robust bone-to-bone repair.
  • Subscapularis Tenotomy: An alternative, involving transection of the subscapularis tendon 1.5-2 cm medial to its insertion. This requires careful repair.
  • Tag the subscapularis for later repair.
• Capsulotomy: Incise the anterior capsule longitudinally, extending from the superior labrum to the inferior aspect, allowing dislocation of the humeral head.
• Humeral Head Resection:
  • Dislocate the humeral head anteriorly.
  • Use a humeral head osteotomy guide specific to the implant system. The cut is typically made in 30-40 degrees of retroversion, at the level of the anatomical neck, removing approximately 8-10 mm of cartilage.
  • Harvest the resected humeral head for bone grafting if needed.
• Glenoid Preparation:
  • Retract the humerus posteriorly and inferiorly to expose the glenoid. Use specialized glenoid retractors.
  • Assess glenoid bone loss and version. Ream the glenoid to a flat, congruous surface, correcting for retroversion or superior inclination as needed. Eccentric reaming may be used to reduce posterior bone loss.
  • Prepare drill holes for the glenoid component pegs or a slot for a keeled component.
  • Perform trial glenoid component placement.
• Humeral Preparation:
  • Ream the humeral canal progressively.
  • Broach the metaphysis to create the appropriate cavity for the humeral stem.
  • Perform trial humeral stem and head component placement, ensuring proper offset, retroversion, and stability through full ROM. Adjust head size and neck length as needed to achieve optimal soft tissue tension and stability.
• Component Implantation:
  • Insert the definitive glenoid component (cemented, uncemented, or hybrid). Ensure all pegs/keel are fully seated.
  • Insert the definitive humeral stem (cemented or uncemented) with the appropriate retroversion. Impact the definitive humeral head onto the taper.
• Reduction and Closure:
  • Reduce the humeral head onto the glenoid.
  • Assess stability and ROM.
  • Repair the subscapularis (bone-to-bone with non-absorbable sutures through drill holes in the lesser tuberosity, or tendon-to-tendon for tenotomy). Strong repair is crucial to prevent anterior instability.
  • Close the capsule, reapproximate the deltopectoral interval, close the subcutaneous tissue and skin.

2. Deltopectoral Approach for Reverse Total Shoulder Arthroplasty (rTSA)

The initial incision and exposure of the deltopectoral interval are identical to TSA. However, the subsequent steps differ significantly to accommodate the reversed anatomy.

• Subscapularis Management:
  • In CTA, the subscapularis is often deficient or irreparably torn. If present, it may be partially released but is rarely repaired fully in rTSA, as it can impinge on the prosthesis or lead to failure. Complete tenotomy is often performed without repair.
• Capsulotomy and Dislocation:
  • The anterior capsule is incised. The humeral head is dislocated.
• Humeral Head Resection:
  • A straight osteotomy of the humeral head is performed, typically at 0-20 degrees of retroversion, to facilitate placement of the humeral tray. The cut is usually slightly more proximal than in TSA.
• Glenoid Preparation (Critical Step):
  • Expose the glenoid. Clear all remaining cartilage, osteophytes, and soft tissue.
  • Central Guide Pin Placement: Identify the center of the native glenoid or the optimal point for baseplate placement. This is crucial for controlling glenoid version and inclination. Use fluoroscopy to confirm correct placement in the mid-glenoid vault.
  • Glenoid Reaming: Ream the glenoid to a flat surface perpendicular to the central pin. This ensures maximal bone-to-implant contact for the baseplate.
  • Baseplate Fixation: Drill holes for baseplate screws. The baseplate is then secured with screws into the scapular body, often using longer screws in the superior and inferior portions for bicortical fixation. Ensure solid, stable fixation of the baseplate.
  • Glenosphere Impaction: Impact the glenosphere (ball component) onto the baseplate. The glenosphere can be medialized or lateralized. Lateralization can improve deltoid wrapping, reduce scapular notching, and enhance range of motion, but may increase the risk of acromial stress fracture.
• Humeral Preparation:
  • Ream and broach the humerus in a similar fashion to TSA, but the goal is to accept the humeral tray/cup.
  • Perform trial humeral stem and polyethylene liner components. The humeral tray contains a concavity that articulates with the glenosphere. Select the appropriate liner thickness and offset to achieve optimal deltoid tension and stability.
• Reduction and Tensioning:
  • Reduce the humeral tray onto the glenosphere.
  • Deltoid Tension: This is paramount. The arm should be stable through the functional range of motion, but not overly tight. Excessive tension increases the risk of scapular notching and acromial fracture; insufficient tension increases the risk of instability and dislocation.
  • Assess stability in internal and external rotation, adduction, and abduction.
• Closure:
  • Typically, the subscapularis is not repaired.
  • Close the deltopectoral interval, subcutaneous tissue, and skin.

General Intraoperative Considerations for Both Procedures:

• Fluid Management: Maintain adequate hydration.
• Bleeding Control: Electrocautery, topical hemostatic agents.
• Neurovascular Protection: Constant vigilance to protect the axillary nerve and brachial plexus.
• Cementing Technique (if used): Ensure proper bone preparation, cement mixing, and insertion, followed by pressurization to achieve adequate interdigitation.
• Component Orientation: Crucial for success. Use intraoperative fluoroscopy to confirm glenoid baseplate and humeral stem alignment as needed.

Complications & Management

Shoulder arthroplasty, while highly effective, is associated with a range of potential complications. A comprehensive understanding of their incidence and management strategies is vital.

General Complications (Common to most surgeries):

• Infection:
  • Incidence: 1-3% for primary arthroplasty, higher for revisions.
  • Management:
    • Superficial: Oral antibiotics, local wound care.
    • Deep/Periprosthetic Joint Infection (PJI):
      • Acute (<4-6 weeks post-op): Irrigation and debridement with component retention (IDCR) if diagnosed early, followed by targeted IV antibiotics.
      • Chronic (>6 weeks post-op) or failed IDCR: Two-stage revision arthroplasty (explant, antibiotic spacer, prolonged IV antibiotics, reimplantation) is the gold standard. In select cases, one-stage revision may be considered. Resection arthroplasty, arthrodesis, or chronic suppression may be options for patients with contraindications to revision.
• Neurovascular Injury:
  • Incidence: 1-4%, most commonly axillary nerve. Brachial plexus injury is less common but more devastating.
  • Management:
    • Neuropraxia: Observation, expectant management, nerve conduction studies/EMG if no recovery.
    • Neurotmesis/Axonotmesis: Surgical exploration, neurolysis, or nerve repair/grafting if indicated.
• Deep Vein Thrombosis (DVT) / Pulmonary Embolism (PE):
  • Incidence: Low in upper extremity surgery (0.1-0.5%), but potentially lethal.
  • Management: Prophylaxis (mechanical, low-dose aspirin or LMWH for high-risk patients), anticoagulation if diagnosed.
• Intraoperative Fracture:
  • Incidence: 1-5%. Humeral shaft or glenoid rim/vault.
  • Management: Dependent on location and stability. Humeral shaft: ORIF with cerclage wires or plates. Glenoid: Small fractures may be observed; larger, unstable fractures may require screw fixation or revision to a different component.

Specific Complications of Shoulder Arthroplasty:

Decision-Making for Salvage:

Salvage strategies are highly individualized and depend on the type of complication, its severity, patient factors, and the initial prosthesis. Revision arthroplasty, often more complex than the primary procedure, carries higher risks and may result in diminished outcomes. In cases of recurrent infection or severe bone loss, resection arthroplasty or arthrodesis may be considered as final options.

Post-Operative Rehabilitation Protocols

Post-operative rehabilitation is as critical as the surgical procedure itself for optimizing patient outcomes following shoulder arthroplasty. Protocols are typically structured in phases, emphasizing protection, gradual restoration of motion, and progressive strengthening. Specifics vary depending on the surgical procedure (TSA vs. rTSA), rotator cuff repair (if any), surgeon preference, and patient progress.

General Principles:

• Protection: Initial immobilization to allow soft tissue healing.
• Early Motion: Initiate passive and active-assisted range of motion (AAROM) within safe limits to prevent stiffness.
• Progressive Strengthening: Gradually introduce active motion and strengthening exercises.
• Patient Education: Crucial for adherence and understanding precautions.

Phase I: Maximum Protection Phase (Weeks 0-6)

• Goals: Protect surgical repair, minimize pain and inflammation, begin early passive motion to prevent adhesions and maintain cartilage health.
• Immobilization: Sling immobilization is generally required.
  • TSA: Usually for 3-6 weeks, with arm removed for exercises only. If a subscapularis osteotomy/repair was performed, external rotation may be restricted (e.g., <30 degrees).
  • rTSA: Often a shorter immobilization period (1-3 weeks), as deltoid function is immediately leveraged and no rotator cuff repair is typically performed. Sling worn for comfort and protection.
• Exercises:
  • Passive Range of Motion (PROM): Initiated with therapist guidance. Pendulum exercises, supine passive forward elevation (to 90-120 degrees depending on comfort/surgeon), external rotation (limited for TSA to protect subscapularis).
  • Scapular Mobilization: Gentle scapular glides and retraction exercises to maintain scapulothoracic rhythm.
  • Elbow, Wrist, Hand ROM: Active exercises to prevent stiffness and maintain upper extremity circulation.
• Precautions:
  • TSA: No active internal rotation against resistance or unsupported external rotation (subscapularis protection). Avoid hyperextension. No lifting, pushing, or pulling.
  • rTSA: No active internal rotation combined with extension, no extreme internal rotation or adduction (risk of dislocation). Avoid heavy lifting.

Phase II: Moderate Protection Phase / Early Active Motion (Weeks 6-12)

• Goals: Gradually restore active range of motion, initiate gentle active strengthening, improve shoulder control.
• Sling: Discontinued, except for comfort in public or during sleep.
• Exercises:
  • Active-Assisted Range of Motion (AAROM): Progress from PROM to AAROM using pulleys, sticks, or the unaffected arm.
  • Active Range of Motion (AROM): Gradually progress towards full AROM within pain limits.
  • Gentle Isometric Strengthening: Initiated for rotator cuff (TSA) and deltoid/periscapular muscles (TSA/rTSA). Isometric holds against wall/hand.
  • Light Resistance Exercises: Introduction of light elastic bands for external rotation, internal rotation, abduction, and flexion (emphasizing deltoid for rTSA, rotator cuff for TSA).
• Precautions:
  • Continue to avoid heavy lifting or sudden movements.
  • No overhead activities involving resistance.
  • rTSA specific: Continued emphasis on proper scapular mechanics and deltoid activation patterns.

Phase III: Minimum Protection Phase / Advanced Strengthening (Weeks 12-24+)

• Goals: Maximize strength, endurance, and functional use of the shoulder, prepare for return to specific activities.
• Exercises:
  • Progressive Resistance Training: Using weights, elastic bands, and bodyweight exercises. Focus on all planes of motion and include both open and closed kinetic chain activities.
  • Dynamic Stabilization Exercises: Plyometric drills (for specific athletic populations), balance exercises.
  • Functional Training: Tailored to patient's occupation, hobbies, or sports, gradually simulating required movements.
  • Endurance Training: Repetitive low-load activities.
• Precautions:
  • Gradual return to recreational activities. Avoid contact sports or repetitive overhead heavy lifting in most cases for the long term.
  • Patient education on avoiding high-impact or sudden, forceful movements.

Key Differences in Rehabilitation for TSA vs. rTSA:

• TSA: Greater emphasis on protecting the subscapularis repair and restoring balanced rotator cuff function. Initial external rotation is often limited. Goal is to restore near-normal ROM and strength.
• rTSA: Emphasis on maximizing deltoid function and maintaining appropriate deltoid tension for stability. Active internal rotation in extension and adduction/hyperextension are often restricted initially due to dislocation risk. Goal is often improved functional elevation and pain relief, rather than complete restoration of native ROM. Scapular notching avoidance through controlled motion.

Rehabilitation is a long-term commitment, often extending for 6-12 months, with continued home exercise programs essential for maintaining gains. Close communication between the surgeon and physical therapist is vital for adjusting protocols based on individual patient progress and potential complications.

Summary of Key Literature / Guidelines

The body of literature on glenohumeral osteoarthritis and its surgical management is extensive and continually evolving. Key insights and guidelines inform current best practices.

1. Outcomes and Survivorship:

• TSA: Widely regarded as a highly successful procedure for primary GHOA with an intact rotator cuff, providing reliable pain relief and significant functional improvement. Long-term survivorship rates for TSA are excellent, with 90-95% survivorship at 10 years and 80-85% at 15 years for the humeral component, and slightly lower for the glenoid component due to aseptic loosening.
• rTSA: Revolutionized the treatment of rotator cuff arthropathy and complex proximal humerus fractures in the elderly. Offers superior pain relief and functional improvement, especially active elevation, compared to HA in CTA. Survivorship rates are comparable to TSA, with 10-year survivorship for rTSA ranging from 80-90%. Functional outcomes are generally excellent, particularly for activities of daily living.

2. Glenoid Component Management:

• TSA: Aseptic glenoid loosening remains the most common mode of failure in TSA. Factors influencing loosening include patient age, bone quality, glenoid morphology (retroversion), and component design (pegged vs. keeled, cemented vs. uncemented).
  • Studies have shown advantages of all-polyethylene cemented glenoids in terms of long-term survivorship for well-selected patients.
  • The role of uncemented glenoids remains controversial, with concerns about fibrous ingrowth versus true bony ingrowth.
  • For significant glenoid bone loss or severe retroversion (Walch B2 or C glenoids), bone grafting or augmented glenoid components (e.g., posterior wedges) may be necessary to restore neutral version and maximize component contact.
• rTSA: Glenoid baseplate fixation is critical. Biomechanical studies support bicortical screw fixation, particularly inferiorly, to achieve initial stability. The role of glenoid lateralization (using lateralized baseplates or bone grafts) is an active area of research, with evidence suggesting potential benefits in reducing scapular notching and improving external rotation, but possibly at the expense of increased stress on the acromion.

3. Humeral Component Fixation:

• TSA/HA/rTSA: Both cemented and uncemented humeral stems provide good long-term results.
  • Cemented stems: Historically the gold standard, particularly in older patients with poorer bone quality. Provide immediate stable fixation.
  • Uncemented stems: Increasingly popular, especially in younger, active patients with good bone quality, aiming for biological fixation. Short stems are gaining traction, potentially reducing stress shielding and easing revision.
• The decision between cemented and uncemented stems often comes down to surgeon preference, patient age, bone quality, and experience with a particular system.

4. Patient Selection and Optimization:

• Age and Activity Level: While arthroplasty is primarily for older patients, indications for younger patients (e.g., AVN) are evolving. Younger patients require careful consideration due to higher activity levels and longer life expectancies impacting implant longevity.
• Comorbidity Management: Optimizing medical comorbidities (diabetes, smoking cessation, nutrition) pre-operatively is paramount to reduce complications, particularly infection.
• Psychological Factors: Patient expectations and psychological readiness for surgery and rehabilitation can significantly influence outcomes.

5. Emerging Technologies and Future Directions:

• Navigation and Patient-Specific Instrumentation (PSI): Computer navigation and 3D-printed PSI are increasingly used to achieve accurate glenoid component placement, particularly for complex deformities, with evidence suggesting improved anatomical restoration.
• Advanced Imaging: High-resolution CT and MRI continue to refine pre-operative planning.
• Biologics: The role of biologics (e.g., PRP, stem cells) in early OA or as adjuncts to arthroplasty is under investigation, though robust evidence for their efficacy in advanced GHOA is lacking.
• Revision Strategies: Evolving techniques for managing complex revision cases, including massive bone loss, PJI, and chronic instability.

6. Key Guidelines:

• American Academy of Orthopaedic Surgeons (AAOS): Provides clinical practice guidelines for the treatment of GHOA, although these tend to focus more on non-operative management and general indications, rather than granular surgical technique.
• American Shoulder and Elbow Surgeons (ASES): Their annual meetings and publications are key sources for consensus and evolving trends in shoulder arthroplasty.

In conclusion, shoulder arthroplasty for GHOA has evolved significantly, offering excellent long-term relief and functional restoration. Continued advancements in implant design, surgical techniques, and rehabilitation protocols, guided by high-level evidence, aim to further improve outcomes and address remaining challenges.