Drill bit failure without implant involvement--an intraoperative complication in orthopaedic surgery.

The aetiology, frequency and consequences of drill bit failure during surgical intervention in human and animal bone tissue are investigated and discussed to provide the surgeon confronted with this problem with a scientifically based procedure. The literature on this subject is rather inadequate, i.e. only one publication in the last decade could be found dealing with this topic and this was a veterinary case. The Laboratory for Experimental Surgery in Davos has received several enquiries from the medical profession worldwide as to correct procedure in the case of drill bit failure. Three sources of information were investigated in order to furbish a reply to these enquiries, these were the AO/ASIF documentation centre in Berne, a survey of 280 surgeons and orthopedic doctors in Switzerland and a survey of 83 AO/ASIF foundation members. One broken tap (tool steel) was removed two years after the operation and metallographic investigations carried out. A frequency of 3 drill bit failure per 1000 internal fixations (0.3%) is apparent in nearly all data. The reasons for drill bit failure were investigated. Drill bit failure occurs more frequently in the proximal femur and when using angled plates. On the basis of this enquiry the following guidelines can be offered to the surgeon. A broken drill bit which is not in contact with an implant can be left in the body without any risk of delayed recovery. However, if the drill fragment is situated near a joint or if it can be easily removed without further trauma to the bone, then it should be removed. Once the fracture has healed the broken drill bit should be removed along with the implant provided no exceptional difficulties are involved.