Table 3 Complication due to surgery (each subject could have more than one complication)

Complication No of patients At treatment site:     Dural tear 5     Excessive bleeding 3     Implant problems 5     Bone fracture 1     Vascular injury 1     Loss of purchase or fixation 3     Broken drain 1 Associated with surgical approach:     Vascular injury 1     Other (loss of swab 1, peritoneal tear 2) 3 Systemic:     Haemorrhage 1 Further surgery (up to 2 years' follow-up) 11

A total of 19 patients had complications as a result of surgery.