What is the role of a hookplate in treating acromioclavicular (AC) joint injuries?

Role of Hookplate in Treating Acromioclavicular (AC) Joint Injuries

Hookplates are primarily indicated for surgical treatment of acute Rockwood type-V acromioclavicular joint dislocations, but they are associated with higher rates of complications including subacromial impingement, acromion osteolysis, and degenerative changes compared to other fixation methods. 1

Indications for Hookplate Use

• Hookplates are used to secure ligament repair in displaced acromioclavicular joint dislocations, particularly in conjunction with procedures like the Weaver-Dunn technique 2
• They provide excellent reduction and stable mechanical environment for healing in chronic AC dislocations when combined with ligament transfer 3
• Hookplates can be used for distal clavicular fractures with AC joint involvement 2

Advantages of Hookplate Fixation

• Provides immediate stability to the AC joint by engaging below the acromion while securing to the clavicle 2
• Allows for early return to work and sports activities (mean period of three months) 2
• Creates a stable environment for healing of ligament transfers in chronic cases 3
• Achieves acceptable joint alignment in most patients post-surgery 4

Limitations and Complications

• Significantly lower functional outcomes compared to other fixation methods like multistrand titanium cable (MSTC) before implant removal (Constant score 76.7 vs 95.8) 1
• Higher rates of degenerative changes in the AC joint (66.7% with hookplate vs 12.5% with MSTC) 1
• Common complications include:
  • Subacromial impingement requiring implant removal 1
  • Acromion osteolysis due to transarticular fixation 1
  • Potential for hook dislocation 4
  • Risk of redislocation after plate removal (reported in 12% of cases) 4

Clinical Outcomes

• Functional improvement is typically seen after hardware removal in patients treated with hookplates (Constant score improvement from 76.7 to 86.1) 1
• Most patients can return to preoperative activity levels following treatment 5
• MRI evaluation shows healing of coracoclavicular ligaments in approximately 88% of cases 18 months after trauma 4

Surgical Considerations

• Proper contouring of the hook plate is essential to fit under the acromion and avoid overreduction of the clavicle 3
• When combined with modified Weaver-Dunn procedure, better outcomes are achieved by transferring the coracoacromial ligament with attached acromial bone rather than ligament alone 3
• Hardware removal is typically recommended 8-12 months after the primary operation 1

Alternative Treatment Options

• For displaced midshaft clavicle fractures, plate fixation with manufacturer-contoured anatomic plates is preferred due to lower rates of implant removal 6
• Anterior inferior plating may lead to lower implant removal rates compared to superior plating for clavicle fractures 6
• Intramedullary nailing provides equivalent long-term clinical outcomes to plate fixation with similar complication rates for clavicle fractures 6

Decision-Making Algorithm

1. Assess the type and grade of AC joint injury (Rockwood classification) 4
2. Consider patient factors (age, activity level, expectations) 7
3. For acute Rockwood type-V AC dislocations, consider alternative fixation methods like coracoclavicular stabilization with multistrand titanium cable due to superior functional outcomes 1
4. If hookplate is selected, plan for hardware removal after 8-12 months 1
5. Inform patients about the potential need for a second surgery for hardware removal and possible complications 1