AC Joint dislocation
Dislocation of the acromio-clavicular joint
can be stabilized by surgical ligament reconstruction
AC joint injury
In Queenstown this is a common mountain biking injury. It frequently occurs when a rider goes over the handlebars landing onto the tip of the shoulder. In the uninjured shoulder the ACJ is the only bony connection between the shoulder girdle and the rest of the body and easily susceptible to injury.
The joint is held down by the coraco-clavicular (C-C) ligaments below, and stabilised front-to-back by the dorsal capsule of the ACJ. Usually when there is complete rupture the clavicle is pulled upwards by the neck muscles and there is a visible lump where the end of the clavicle is protruding.
Injury types
ACJ injuries are usually described by the Rockwood classification. Grades 1 and 2 are characterized by intact C-C ligaments, whereas grades 3-6 are complete ruptures with dislocation in various directions.
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Grade 1 : sprain
Grade 2 : ruptured AC ligaments but the C-C ligaments are intact
Grade 3 : complete rupture of both ligaments. (<100% C-C gap increase)
Grade 4 : complete rupture of both ligaments. Displaced backwards
Grade 5 : complete rupture of both ligaments. (>100% C-C gap increase)
Grade 6 : complete rupture of both ligaments. Displaced underneath coracoid.
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Most patients with a deformity that is confirmed on X-ray will have at least a grade 3 ACJ dislocation.
Should I have surgery?
Grades 1 & 2 ACJ injuries do not require surgery. They are still quite painful for several weeks/months but intact C-C ligaments will ensure healing without deformity.
Grades 3-6 all involve complete ligament disruption of both the A-C and C-C ligaments. Grade 3 injuries can be treated non-surgically but it is recommended to operate on the higher grade injuries. If you perform shoulder intensive sports or a lot of overhead activities (eg ceiling painter) then repair of grade 3 injuries is also worthwhile.
If the injury is long-standing or the is pre-existing ACJ degeneration it may be better to leave the clavicle dislocated, or excise the distal clavicle and reconstruct which is a more complicated procedure. Some people elect not to have surgery. They tend to have persistent instability which is visible but may still lead to acceptable shoulder function
Surgery
Some surgeons only address the C-C ligaments without stabilising the A-C joint. At QJC we repair both ligaments using an open approach. This ensures maximum stability and strength of repair, as well as an anatomic reduction of the dorsal capsule that cannot be achieved with a keyhole type approach.
The foundation of the repair is a C-C ligament reconstruction using a loop or a button. then a posterior band to resist forward motion, as well as a dorsal ACJ capsular reconstruction.
What are the risks of surgery?
Grades 1 & 2 ACJ injuries do not require surgery. They are still quite painful for several weeks/months but intact C-C ligaments will ensure healing without deformity.
One of the biggest problems in ACJ stabilization if the high loads that pass though such a small joint. The is one of the reasons that the clavicle is one of the common fractures in adults. Stabilization can increase the stress and create weakness where fixation is achieved in the coracoid, acromion and clavicle. Fracture can occur at any of these sites.
Frequently patients have grazes over the tip of the shoulder the increase the risk of infection. Infection of the fixation and ligament graft would require treatment with antibiotics at least and potentially further surgery and hospitalization. The skin needs to be healed, dry and infection free before surgery.
There are also risks of anaesthetic that your anaesthetist will discuss. There are also standard surgical risks including medication reactions, blood clots, bleeding, stroke/death. These are all of course very rare and most patients have a short and reliable surgery and recovery.
In the long term it is common for the clavicle to be prominent as most repairs do stretch a little. Additionally the cartilage damage from dislocation may lead to pain and arthritis in the long term that can be addressed should that occur.
Stabilization does not make one immune from repeating the initial injury. Furthermore if the stabilization is especially strong a repeated fall may lead to fracture of the clavicle though the fixation point.
General advice regarding AC joint stabilization
The information here is general and varies depending on individual factors such as: time to treatment, strength of repair, occupation, age and sporting demands.
Will surgery benefit?
Grade 4-6 dislocations & Grade 3 dislocations in the active person
Immobilisation
Sling for 6 weeks
Driving
no Driving for 6 weeks
Aim for surgery
Reduce and stabilize the dislocation
Reconstruct both AC and CC ligaments
Hospital stay
Day surgery only
Return to Work
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1 handed duties at 2 weeks
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light duties at 6 weeks
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full duties at 12 weeks
Investigations
erect X-ray required
Sometimes additional chest views
Therapy
Shoulder exercises after 6 weeks