Whilst there is little debate on the treatment of type 1&2 (conservative), and type 4-6 (surgery), type 3 injuries continue to present a clinical dilemma. Historically, these fractures were treated conservatively and there are numerous papers to support this approach. With newer advances in arthroscopic techniques, there are growing proponents of early ligament reconstruction, although so far there is no clear evidence of potential benefits.
Athletes, or young active patients involved in heavy overhead lifting are more likely to benefit from early surgery. For others, in line with the available evidence, my preferred treatment is to start with conservative treatment including targeted rehabilitation. The AC joint remains permanently prominent, but is generally stabilised by the fibrous tissue. Most patients can therefore regain full movements and strength in due course. In a small minority of patients with persistent instability after 6 months, I offer surgical stabilisation.
The challenge lies in identifying such patients early who are likely to remain unstable in the longer term. Although no test is 100% sensitive, I have found the “Arm adduction test” to be useful. Once the pain from trauma settles down and patient has regained ROM in around 6 weeks, I assess them in the clinic. With the arm flexed to 90 degrees, if active adduction causes further increase in prominence and instability, in my experience I find these patients will continue to be unstable in the longer term and therefore may benefit from earlier surgical intervention.
Increased prominence and instability in Flexion + Adduction
Surgical techniques have constantly evolved over the years and can be broadly divided as follows:
A) Transacromial or subacromial Stabilisation: This is mostly of historic interest. Hook plates are still used to ‘fix’ the ACJ but since it does not address the fundamental issue to C-C ligament tear, the clavicle usually dislocates as soon as the plate is removed. Most specialist Shoulder surgeons have given up using this plate except in special circumstances.
B) Direct fixation of coracoid to clavicle (eg Bosworth screw): Provides secure initial fixation but loosens or breaks over time, has been largely abandoned.
C) Non anatomic reconstruction using Coraco-acromial ligament (Weaver Dunn repair): This provides an attractive option of using CA ligament to substitute for the torn C-C ligament. Advantage of being native tissue with good strength, but is a non anatomic repair. Still popular as a primary or salvage procedure.
D) Coracoclavicular ligament reconstruction using tendon grafts or synthetic ligaments: This is the current treatment of choice. The main advantage is that it is more anatomic than other methods of repair. Can be performed arthroscopically but it relies on drilling a hole through the coracoid, thus risking a fracture. I therefore favour an open procedure in which the graft is looped, rather than drilled through the coracoid.
The choice between synthetic and tendon graft is based on surgeon’s preference. Synthetic grafts today are very strong and reliable but have a risk of osteolysis (1) and can potentially stretch out over time. It also entails a small risk of rejection, being a foreign material. Tendon grafts involve extra morbidity (in case of autograft), but mitigate against the risk of late osteolysis or rejection.
There are many techniques to fix the graft, I personally loop the graft around coracoid and fix it through anatomic footprint of native ligament. Others rely on an interference screw or bicortical screw. Whatever technique is used, postoperative rehabilitation is a very important aspect in achieving success, and participation in competitive sports usually takes around 6 months.
AC joint stabilisation is challenging surgery. Apart from the usual surgical risks, there is also a risk of failure of the ligament reconstruction necessitating further surgery. So far there is no gold standard procedure for these injuries (hence the title of the post!), partly due to huge variation in presentation, but also from the enormous stresses that pass through the ligament during movements of arm, multiplied manifold during sporting activities. Most patients do well with modern surgical techniques, but it is important to thoroughly counsel them before surgery to manage expectations and explain the prognosis.