Pudendal nerve palsy in trauma and elective orthopaedic surgery

The incidence of pudendal nerve palsy following routine trauma and elective orthopaedic surgery procedures ranges from 1.9% to 27.6%. Excessive and/or prolonged traction against the perineal post of a traction table, leading to direct compression and localised ischaemia to the nerve are suggested mechanisms of injury. Misuse of traction and the inappropriate placement of the perineal post, leading to crushing and stretching of the pudendal nerve, are two main contributing factors leading to its postoperative palsy. The sequelae may be sensory, motor or mixed. In most cases, these injuries are transient and tend to resolve within several weeks or months. However, complete neurological recovery may be unpredictable and the effects of ongoing dysfunction potentially disastrous for the individual. In terms of preventative measures, magnitude and duration of traction time should be minimised; traction should be limited to the critical operative steps only. Additionally, the perineal post should be placed between the genitalia and the contralateral leg. A well-padded, large-diameter perineal post should be used (>10cm). Adequate muscle relaxation during anaesthesia is particularly important in young men who have strong muscles and thus require larger traction forces when compared to elderly patients. Orthopaedic surgeons should be aware of the pathophysiology behind the development of this palsy and the measures that can be employed to reduce its occurrence. In procedures where a traction table is employed, consenting for pudendal nerve palsy should be considered by the surgical team.