What is the AC or Acromio-Clavicular Joint?
The Acromio-Clavicular Joint is a small joint between the outer end of the clavicle and the acromial process of the scapula. Acromio-Clavicular Joint is commonly abbreviated to AC Joint. Although a small amount of movement occurs at the AC Joint it’s more important role is to stabilise the scapula or shoulder blade on the chest wall. This in turn provides a stable foundation for the entire shoulder joint. The AC Joint may dislocate due to injury.
What is AC Joint Reconstruction?
AC Joint Reconstruction is a surgical procedure which restores the anatomy of a dislocated AC Joint. Dislocation of the AC Joint is due to rupture to varying extent of the AC Joint Capsular Ligaments, the Coraco-Clavicular Ligaments and muscle attachments near the joint. The extent of the tearing may influence the type of reconstruction required. Although the torn ligaments may not be able to be repaired directly the reconstructive surgery is designed to hold the AC Joint in a reduced position while the torn soft tissue structures heal strongly enough to keep the joint stable.
Reconstruction for Acute AC Joint Dislocation
If the AC Joint Injury is recent an early reconstruction has the advantage of the torn ligaments of having the best chance of healing. Ideally surgery is best undertaken within about 2 to 3 weeks of injury. Many surgical techniques have been described to achieve AC Joint stability. Whichever technique is chosen the goal is to align the Acromion with the Clavicle and maintain the alignment while the torn ligaments heal. Common techniques include:
- Coraco-Clavicular Screw (A screw between the clavicle and coracoid process of the scapula)
- Hook Plate (A plate applied to the clavicle with a hook that sits under the acromion to hold the joint in place)
- Synthetic Ligaments (Strong sutures or tape wrap around the clavicle and coracoid process to keep the joint aligned)
Reconstruction for Chronic AC Joint Dislocation
If the AC Joint has been dislocated for more than 6 to 8 Weeks the torn ligaments may have retracted and will have lost the capacity to heal. The joint cartilage is likely to have deteriorated as well. This type of chronic dislocation may require a different surgical technique. The compromised ligaments may require augmentation with a synthetic ligament or a soft tissue supplement such as a Coraco-Acromial Ligament Transfer. If the joint has become arthritic a small portion of the outer end of the clavicle may need to be removed.
Surgical reconstruction of the AC Joint will usually require a 2 day admission to hospital. Use of a sling in the first 2 weeks following surgery is recommended to avoid any unexpected load on the joint. However it is possible to remove the sling at home to shower and dress and perform light waist level tasks. The physio will have shown you how to perform some gentle exercises in those early weeks.
During the next 6 weeks light shoulder level activities can be performed. But once again caution needs to be exercised to minimize the risk of disrupting the surgical reconstruction. If a metal screw or plate has been used as part of the reconstruction it may require removal as a day surgery procedure approximately 2 months after the initial surgery. Then a structured physiotherapy program can be commenced to address any shoulder stiffness or muscle weakness. It may take as long as 3 to 4 months from the time of surgery that your shoulder feels close to normal.