 He resigned after the medical staff was blamed after a 3–1 loss to Porto in a UEFA Champions League match, and rejoined after the reappointment of Jupp Heynckes as coach.Many of the German doctor's treatments are controversial, including using injections of a substance called Hyalart, extracted from the crest of cockerels, which is claimed to help lubricate knee injuries and take away the pain.He has also injected Myo-Melcain, which is the painkiller Procaine in a honey solution, or Actovegin into patients' muscles.