HTO is the process of ectopic bone formation . it can occur, as previously mentioned in MT junctions and can potentially occur at any joint but more commenly the knee, hip, shoulder or elbow. Early detection is difficult as often onset is insidious with pain, swelling and heat with a reduction of range of movement noted in the area. Diagnosis is confirmed by bone scans where it shows as an area of active uptake.
The effectiveness of physio in HTO remains controversial. Maintaining range of movement in the area is vital so the joint does not fuse however it is not known if too vigorous a mobilisation could affect the process. Splinting could also be of use to maintain a position but care must be taken that the joint is still ranged so it does not fuse in the splinted position.
HTO can be treated with medication (I think indomethacin may be one of the ones used) and if it should come to it corrective surgey usually isn't carried out until the HTO is inactive. This may be up to 2 years after the injury and is shown by inactivity on bone scan.
It can adversly affect rehab due to pain as well as ROM, I guess making sure pain relief is sufficient and ensuring a good ROM in the joints surrounding the area is a start.