You are correct. There is limited information about the long term outcomes following posterior sternoclavicular dislocations. The primary reason has to do with the small number of cases in the literature. Anterior sternoclavicular dislocation account for 90-95% while posterior only 5-10%.
There are no real guidelines for many of the questions you have asked.
Will I suffer longterm complications?
If you avoided any significant injuries with the initial injury (ie. no injury to the blood vessels, lungs or trachea then the most common long term complications are development of arthritis in the joint and possible recurrent instability. There is little data in the literature to provide exact numbers.
Will I be able to endure my regular physical sports a year from now and not risk dislocation again?
Yes. I would be very surprised if you were not able to do all sports. Assuming the reduction was successful and stays in place then your risk of re dislocation is probably only 5-10%. Again, there is little literature to support this for posterior dislocations. Most recurrent dislocations occur with anterior dislocation.
If I dislocate it again - can it pop out faster and result in death as usually is the case of this type of injury?
I would estimate that your risks of injury to the blood vessels is at most only slightly higher than with the initial injury. The estimated risks of a complication from a posterior sternoclavicular joint are 25%.
What can I do to ensure the ligaments tighten and heal properly?
Don't do too much too soon. How long is too soon? No one really knows but I would definitely avoid contact sports or other activities (ie. if you can hit the ground or a wall consider it a contact sport) for 3 months minimum.
Is there a way to find out if the ligaments did heal properly all around the joint?
Clinical exam is probably as realiable as any other test. An MRI will show lots of changes in the soft tissues for a long time and would not clearly show the ligaments.
Is my joint weaker as most other common dislocations are such as shoulder dislocations?
Again, there is no good evidence to answer this question but based on other joint dislocation it most likely will have some increased mobility/motion compared to the other side. You might also notice that it remains more swollen than the other side.
Or does the body have a backup plan because the type of injury this is it would heal better then most other joints?
No backup plan. Give the body time to heal itself. Don't do too much too soon. Avoid contact sports/activities for 3-6 months minimum.
Great questions. Unfortunately there is little in the literature to provide you with well supported answers.
Regards
Christian
Christian Veillette M.D., MSc., FRCSC
Shoulder and Elbow Reconstructive Surgery
Toronto Western Hospital, University Health Network
UHNArthritisProgram.ca
Orthogate.org
OrthopaedicsOne.com
OrthopaedicWeblinks.com