What is the step by step procedure for shoulder hemiarthroplasty?

Step-by-Step Procedure for Shoulder Hemiarthroplasty

Shoulder hemiarthroplasty is a surgical procedure that involves replacing only the humeral head component of the glenohumeral joint while preserving the native glenoid. This procedure is typically indicated for patients with osteoarthritis limited to the humeral head, comminuted humeral head fractures, or in patients with deficient glenoid bone stock 1.

Preoperative Planning

1. Patient Selection:

   • Ideal candidates include patients with osteoarthritis limited to the humeral head
   • Patients with comminuted humeral head fractures
   • Patients with deficient glenoid bone stock
   • Patients with greater preoperative comorbidities requiring shorter operative time 1

2. Imaging Assessment:

   • Radiographs in multiple planes (AP, axillary, scapular Y views)
   • CT scan to evaluate bone quality and glenoid morphology
   • MRI if rotator cuff integrity needs assessment

Surgical Procedure

1. Positioning and Anesthesia

• Position patient in beach chair or lateral decubitus position
• General anesthesia with or without regional block

2. Surgical Approach

• Deltopectoral approach (most common):
  • Make 10-15 cm incision from coracoid process extending distally along deltopectoral groove
  • Identify and protect cephalic vein
  • Develop interval between deltoid and pectoralis major
  • Retract cephalic vein laterally with deltoid or medially with pectoralis major

3. Exposure

• Identify and release the subscapularis tendon:
  • Either perform tenotomy 1 cm medial to lesser tuberosity or
  • Perform subscapularis peel from lesser tuberosity
• Tag subscapularis with heavy non-absorbable sutures for later repair
• Perform anterior capsulotomy
• Dislocate humeral head anteriorly by external rotation, extension, and adduction

4. Humeral Head Preparation

• Identify anatomical neck and perform humeral head osteotomy:
  • Use cutting guide to ensure proper resection angle (typically 20-30° retroversion)
  • Resect humeral head at anatomical neck
• Measure resected humeral head to determine appropriate prosthesis size

5. Humeral Canal Preparation

• Identify entry point for intramedullary canal (typically posterior to bicipital groove)
• Ream medullary canal progressively to appropriate size
• Broach humeral canal to appropriate size for selected implant

6. Trial Reduction

• Insert trial stem and head components
• Perform trial reduction to assess:
  • Stability through range of motion
  • Appropriate tension
  • Head size and height
  • Version (typically 20-30° retroversion)

7. Final Implantation

• Remove trial components
• For cemented technique:
  • Insert cement restrictor
  • Prepare cement and insert into canal
  • Insert final stem with appropriate version
• For press-fit technique:
  • Insert final stem with appropriate version
• Attach final humeral head component
• Perform final reduction

8. Closure

• Repair subscapularis tendon with heavy non-absorbable sutures
• Close rotator interval
• Close deltopectoral interval
• Close subcutaneous tissue and skin in layers

Special Considerations for Fracture Cases

When performing hemiarthroplasty for proximal humeral fractures:

1. Tuberosity Management:

   • Identify and preserve tuberosity fragments with attached rotator cuff
   • Tag tuberosities with heavy non-absorbable sutures
   • After stem implantation, secure tuberosities to prosthesis and humeral shaft
   • Proper tuberosity healing is critical for good functional outcomes 2, 3

2. Height and Version Considerations:

   • Restore appropriate humeral height using anatomical landmarks
   • Maintain 20-30° of retroversion

Postoperative Management

1. Immobilization:

   • Sling immobilization for 4-6 weeks

2. Rehabilitation Protocol:

   • Phase 1 (0-6 weeks): Passive range of motion exercises
   • Phase 2 (6-12 weeks): Active-assisted range of motion exercises
   • Phase 3 (>12 weeks): Progressive strengthening exercises

Potential Complications

1. Early Complications:

   • Infection
   • Nerve injury (axillary, musculocutaneous)
   • Intraoperative fracture
   • Instability

2. Late Complications:

   • Glenoid erosion (most common complication, occurring in up to 20.6% of cases) 1
   • Prosthetic loosening
   • Tuberosity nonunion or malunion (in fracture cases)
   • Stiffness
   • Rotator cuff tears

Technical Pearls and Pitfalls

Pearls:

• Ensure proper version (20-30° retroversion) to optimize stability and function
• Accurately restore humeral head height and offset
• Preserve as much bone stock as possible for potential future revision

Pitfalls to Avoid:

• Improper version leading to instability
• Excessive humeral head size causing overstuffing of the joint
• Inadequate tuberosity fixation in fracture cases
• Subscapularis failure due to improper repair

Outcomes

Shoulder hemiarthroplasty typically provides good pain relief but variable functional outcomes 4. Success rates are higher in:

• Younger patients
• Acute rather than chronic cases (for fractures)
• Cases with proper surgical technique and rehabilitation 5, 6

The 10-year prosthetic survival rate can reach 93.9-96.6% with proper technique and patient selection 2, 3.