We report on a patient with tetraspasticity due to perinatal cerebral palsy requiring total hip joint endoprosthesis because of hip dysplasia. In order to minimize the risk of postoperative luxation Botulinum Toxin A was injected preoperatively into hip flexor and adductor muscles guided by CT-fluoroscopy. Outcome measures included muscle tone, limb position and self-reported pain relief. Seven days post injections the tone of the right hip flexor and adductor muscles improved from three to one points on the five-point Modified Ashworth Scale (MAS), the spastic joint position improved from 45° to 20° in flexion and from 20° to 10° in adduction, and the patient was free of pain. Ten days after injection of Botulinum Toxin operation of total hip joint arthroplasty was performed without complication. Improvement of spasticity sustained for another eight weeks. Subsequent Botulinum Toxin A injection three months post surgery resulted in identical results. This case demonstrates a new preoperative indication for Botulinum Toxin A in patients with an increased muscle tone at the hip who have to undergo total hip joint endoprosthesis to reduce the risk of postoperative luxation.