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Shoulder Arthrodesis

Shoulder joint fusion, also known as shoulder arthrodesis, is a surgical procedure where the bones of the shoulder joint are fused together, resulting in a single, solid bone. This eliminates movement at the glenohumeral joint but can significantly reduce pain and provide stability when other treatments, such as shoulder replacement, are not suitable.

When Is Shoulder Fusion Considered?

While shoulder replacement surgery is more common today, fusion still plays an important role for certain conditions where joint replacement is not viable. Fusion may be the best option in the following scenarios:

  1. Infection in the Joint: If a bacterial infection causes chronic joint pain and deformity, and if infection persists despite treatment, fusion may be preferred over replacement.
  2. Paralysis in Childhood: Some children suffer from shoulder paralysis due to conditions like brachial plexus injury or polio. Fusion can stabilize the shoulder when muscle transfers aren’t an option.
  3. Deltoid and Rotator Cuff Paralysis: In adults with complete loss of both these critical muscle groups, there’s often not enough power for joint replacement to be useful.
  4. Brachial Plexus Injuries in Adults: After trauma, if some muscles (like the trapezius) are still functional, fusion can provide a stable base for remaining arm movement.
  5. Advanced Rheumatoid Arthritis: In patients with rotator cuff destruction and instability, fusion offers pain relief and function where replacement is contraindicated.
  6. Failed Shoulder Replacement: When a shoulder prosthesis fails and cannot be replaced—often due to infection or severe bone loss—fusion is the fallback.
  7. Recurrent Dislocations: For people with ongoing shoulder dislocations despite surgeries, fusion can offer permanent stability.
  8. After Tumor Surgery: If the top part of the humerus has to be removed due to cancer, fusion may be done to restore strength.
  9. Severe Rotator Cuff Tears: In cases where multiple repairs have failed and muscle function is lost, fusion might be needed.
  10. High-Force Jobs: Workers who need strength more than flexibility (like manual laborers) may benefit from a fused shoulder that doesn’t move but can handle loads.
  11. Immunocompromised Patients: Individuals on immunosuppressive treatments or with HIV/AIDS have higher infection risks after joint replacement, making fusion a safer choice.
  12. Tuberculosis of the Shoulder: Historically a common reason for fusion, it’s now less frequent due to effective medications but still a valid indication in resistant cases.

Preparing for Surgery: What to Consider

Before surgery, several factors are evaluated to ensure the best possible outcome:

  • Muscle Strength: Muscles around the shoulder blade—especially the trapezius, serratus anterior, and rhomboids—need to function well for scapular motion to compensate for loss of shoulder joint movement.
  • Other Joints: The joints near the shoulder, especially the acromioclavicular and sternoclavicular joints, will bear extra stress after fusion. Their condition is important.
  • Previous Injuries or Deformities: Scar tissue, scoliosis, or congenital abnormalities can limit post-fusion motion.
  • Other Arm Joints: If the elbow or wrist is already impaired (e.g., from arthritis), fusion may worsen arm function. Fusion in such cases must be carefully weighed.
  • Children and Teens: In young patients, skeletal growth must be considered, and ideally, fusion is delayed until maturity. If done early, the fused shoulder must be carefully positioned to avoid future deformities.

How Is Shoulder Fusion Done?

Several surgical techniques are available:

  • Intra-articular Fusion: Direct fusion inside the joint using screws.
  • Extra-articular Fusion: Fusion performed outside the joint.
  • Combined Techniques: Both internal and external elements are fused for added strength (often used in children).

Hardware such as screws and plates are used to hold the bones together during healing. Bone grafts may be used to encourage bone growth across the joint. In some cases, special plates like pelvic reconstruction plates are used, which can be molded to fit the shoulder and usually don’t need to be removed later.

Functional Goals

After surgery, the goal is to maintain a stable shoulder that allows:

  • Reaching the mouth and face
  • Supporting the hand in daily tasks
  • Lifting and pushing motions

The fused arm will not lift overhead, but many patients return to their jobs or daily activities that do not require overhead movement.

Common Complications

Though helpful in specific cases, shoulder fusion carries risks:

  1. Functional Limits: Overhead tasks like painting or climbing are difficult or impossible.
  2. Nonunion (Pseudarthrosis): The bones may fail to fuse, occurring in 5–20% of cases.
  3. Malposition: Incorrect angles during surgery can impair arm function.
  4. Distal Joint Stiffness: The wrist or elbow may become stiff due to reduced use.
  5. Humerus Fractures: Can happen in up to 15% of cases due to stress on the arm.
  6. AC Joint Dislocation: May occur if this joint was already arthritic.
  7. Nerve Irritation: Excess abduction can stretch nerves and cause pain.
  8. Infection: Occurs in about 3–5% of cases.
  9. Hardware Migration: Pins or screws may move, especially if not secured properly.
  10. Epiphyseal Damage in Children: If done before bone maturity, it may stunt growth.
  11. Allograft Complications: If donor bone is used, infection or rejection risks increase.

Optimal Shoulder Positioning

Getting the fusion angles right is crucial. If fused at the wrong angle, patients may not be able to perform basic tasks like eating or dressing.

Typical recommended fusion angles for adults:

  • Abduction: 20–30°
  • Forward Flexion: 25–30°
  • Internal Rotation: 25–40°

These angles allow patients to keep the arm comfortable by the side and still use it for daily tasks. Internal rotation is particularly important—without it, reaching the body midline is very difficult.

Fusion in Children

Fusion in young patients requires extra care:

  • Growth Impact: Since the shoulder’s growth plate contributes heavily to upper arm growth, early fusion can lead to a shorter arm.
  • Angle Adjustments: Some surgeons advocate fusing at a higher abduction angle (up to 90°) in younger children to account for changes during growth.
  • Timing: Ideally delayed until at least 10 years of age to avoid complications.
  • Recommended Angles: 45° abduction, 25° forward flexion, 25° internal rotation for children.

Despite these complexities, children often do very well after fusion if the rest of the arm is functional. The key is carefully planned positioning and delaying the procedure when possible.

Conclusion

Shoulder fusion is a valuable surgical option in selected patients where shoulder replacement is not viable. Though it results in loss of joint motion, it can dramatically reduce pain, improve function, and restore quality of life—especially when arm power is more important than mobility.