I don't really know that there's a lot more known today for Bo's injury. In the early 90s, I took a nasty fall on a ladder from 13'. Since I was at the top, my head dove in first (ladder rung caused 25 stitches between my eyes). When the bottom of the ladder came down, my foot was stuck through a rung. This rotated my trocantor (head of the femur) against the back of my left hip socket, fracturing it. IOW, it was the same injury as Bo, except that his toe was dug into the turf with another hefty player landing on top. Mine was my own weight, from 13'. I had ski reservations made for Grand Targhee, so I went ahead and took the trip, with only one fall that really worried me (lotsa powder there). A few months after that, Bo's condition came to light and I suggested to my ortho that we do followup x-ray. Thankfully, all the bone was nice and gray. I haven't researched it lately, so I don't know if better predictors for necrosis have come along, much less if there's anything other than replacement which can be done. I may be wrong, but I don't remember there being any underlying precondition. In fact, I don't know how you'd know it, unless the initial x-rays showed chalky white on the trocantor immediately after the injury. Certainly there would have been symptoms - significant pain and the like - if the bone had been decaying before the injury.
I'm assuming that CJ's x-rays came back clean for fracture, so we're probably looking at typical dislocation type damage - soft tissue damage. My main worry would be stretching of the big sacral and other attendant ligaments, predisposing to further dislocations, as in a dislocated shoulder.* An ironical advantage OF's have over youngsters is that our ligaments and tendons aren't as flexible and stretchy as younger folk. When an OF dislocates a shoulder, you reduce it, and that's usually end of story. A 20-year old does the same, and, if he returns to activity too quickly, the shoulder capsule components stay stretched, leading to further dislocations until surgery is done to tighten up the joint. The hip is a much more stable joint and, if it's just dislocation, I think he'll be good to go within the forecast 6-8 weeks...
*I once strained that sacral ligament doing, of all things, an installation of a kitchen sink faucet, scrunched up under the counter in an awkward position. Once strained, no posture on earth is comfortable. It took weeks to heal. After it had stabilized, a 16-year old kid rear-ended me here on Governors Drive. I had pulled into the turn lane to try to pick up my wife, whose Passat had quit in rush hour traffic on New Year's Eve. There were no skid marks - he hit me at around 50 MPH, talking on his cell to his parents, telling them he was almost home. His accident report read to the effect that he turned to look at the accident (there was no accident), his car pulled left, and "I hit them and after that I don't remember anything." Well I do remember being airborne, at 90 degrees to the ground, before the Explorer settled back down on four wheels. It was amazing that all I had was mild whiplash and re-straining that same damned sacral attachment, which cost me sleep for another three weeks or so...
