My 10 year old mare went lame in October and was finally diagnosed with a bone cyst just below her fetlock joint and a possible hairline fracture at the beginning of December. I was told by the vet at Newmarket that there was a 60% chance that she would be 100% sound again. She was put on complete box rest and I took her back to Newmarket at the end of January for another x-ray and the cyst was the same size and she was 1/10 lame in trot. Was advised to walk her in hand for 5 mins a day building up each week by another 5 mins. After another trip to Newmarket in April for another MRI I was advised that she could be ridden in walk only and she could be turned out in a small paddock for a couple of hours a day gradually building up to a full day after six weeks, which is this week. I now have to get my local vet out this week to check her to see if I can start trotting her for 5 mins a day gradually building it up as with the walk. Then it is back to Newmarket in 6 weeks time for another x-ray and hopefully the all-clear. She obviously thinks she is better though cos she has taken it upon herself to jump the electric fence a couple of times and then had a go at the higher wire fence around the edge of the field with no ill-effects. I put her on cortaflex in January so whether that has helped or not I dont know. As for the long term effect, the last report I had from Newmarket said that she should be able to do everything she has done before but that there is a greater chance of her getting osteoarthritis when she is older. I hope your horse is ok.
my sec d had one in his stifle. he took a long time to come sound and even after that he would often go very slightly lame. It did help to have a light weight rider rather than a heavier one
My horse was operated on 4th June last year for a subchondral bone lesion in his shoulder joint, he has just finished IRAP treatment. Too soon to tell what the results will be.