Postural musculature is always weakened and postural musculature usage patterns are always altered by surgery. Limping and crutch usage contribute further to this effect. Therefore, strengthening the joint is necessary prior to any extensive work. Attempting high volumes of work (extensive jogging, pool work, etc.) overfatigue the postural musculature and set up improper firing of kinetic chains because of the lack of postural anchoring. This tends to compound the problem and produce others.
The injury cascade information is foggy, but I have seen some maps of what injuries will compound to secondary injuries. The problem is record keeping and short exposure with the athlete. Look for a big rash of issues in weeks 5-6 with teams as the statistical information is hinting to some interesting challenges with the NFL. A good resource on innovative injury updates is Football Outsiders.