The biggest question that must be answered is what needs correction.
If only simple alignment is required, then the implant would not pose a major issue. The implant crown may need remaking after the braces come off since the bite will be altered.
If a more drastic correction is required, especially when extractions are part of the treatment plan, implants may be helpful or may pose an issue for space management.
If the implant is on a back tooth and maximum anchorage is desired (to correct protruding front teeth), then the implant can serve as the perfect skeletal anchor when incorporated into the braces.
If the implant is on a front tooth and significant retraction of the incisors is required, then removal of the implant may be necessary to facilitate this treatment.
Ideally, any orthodontic treatment should be discussed prior to implants to ensure patients are fully aware of the future implications of having an implant placed.