In people that are still experiencing functional instability, or wish to participate in activities that test the ACL (such as those requiring sudden turning, cross cutting or pivoting), a reconstruction of the ACL would also be a reasonable option.
In a reconstruction, a graft (whatever is being used to replace the ACL) is passed along the path of the old ACL (now dysfunctional), tensioned and secured into the bones using tunnels and hardware. The aim is that this graft will reproduce the function of the ACL and keep the knee stable. The ACL Graft can be Autograft (form oneself, commonly Hamstrings), Allograft (from someone else, Cadaveric or Live Donor) or Synthetic Graft (artificial, common one being LARS) or a combination. They all have their perceived pros and cons.
Surgery, in the vast majority of patients, will lead to a successful return to sport and most pre injury activities. However, it is worth emphasizing that the prerequisite for a successful result is compliance (to do as you are told) and a strict intensive rehab program that will go on for a good 6 months. Whilst in most cases return to day-to-day function including work can be expected within a few weeks, sports requiring sudden turning cross cutting and pivoting must be avoided for 8-10 months.