Proper femoral reaming is a key factor for a successful outcome in cementless hip arthroplasty. Good quality reaming minimizes risks of intra-operative femoral fracture during reaming and prevents poor fitting of the implant which can lead to subsidance of the stem postoperativly. Determining the quality of reaming is largely a subjective skill and dependant on the surgeon's experience with no documented intraoprative method to assess it objectively. We recorded and analysed the frequencies of sound signals recorded via a bone conduction microphone during reaming of the femoral canal in a series of 28 consecutive patients undergoing uncemented total hip replacement performed by same surgeon. Hammaring sound frequencies and intensity were analysed by mean of computer software. The relationship between the patterns of the recorded reaming sound frequencies compared with surgeon judgment of the reaming quality intraoparativly and post operative x rays. All patients were followed up clinically and radiologically for 2 years after surgery to determine the integrity of the fix and to evaluate the stability of the prosthesis.Introduction
Method
Many surgeons are familiar with the audible change in the sound pitch while hammering a rasp in a long bone during surgeries like Hip Arthroplasty. We have developed a hypothesis indicating that there is a relationship between that sound change and the development of micro-fracture and subsequently full fracture. An experiment using porcine femur bone performed by attaching a bone conduction microphone to the distal part of the bone while hammering a rasps of different sizes through the medullary canal till the point where a fracture developed. The transduce sound resonances created in the bone during rasping are converted to an analogue electrical signals that were sent to a Zoom H4n handheld recording device which recorded the signal to a disk. The recorded signals subsequently were analysed using Matlab software and a spectrum analyzer using Fast Fourier Transforms (FFT).Introduction
Methods
We examined the rates of infection and colonisation by methicillin-resistant In 2004, we screened 1795 of 1796 elective admissions and MRSA was found in 23 (1.3%). We also screened 1122 of 1447 trauma admissions and 43 (3.8%) were carrying MRSA. All ten ward transfers were screened and four (40%) were carriers (all p <
0.001). The incidence of MRSA in trauma patients increased by 2.6% per week of inpatient stay (r = 0.97, p <
0.001). MRSA developed in 2.9% of trauma and 0.2% of elective patients during that admission (p <
0.001). The implementation of the MRSA policy reduced the incidence of MRSA infection by 56% in trauma patients (1.57% in 2003 (17 of 1084) to 0.69% in 2004 (10 of 1447), p = 0.035). Infection with MRSA in elective patients was reduced by 70% (0.56% in 2003 (7 of 1257) to 0.17% in 2004 (3 of 1806), p = 0.06). The cost of preventing one MRSA infection was £3200. Although colonisation by MRSA did not affect the mortality rate, infection by MRSA more than doubled it. Patients with proximal fractures of the femur infected with MRSA remained in hospital for 50 extra days, had 19 more days of vancomycin treatment and 26 more days of vacuum-assisted closure therapy than the matched controls. These additional costs equated to £13 972 per patient. From this experience we have been able to describe the epidemiology of MRSA, assess the impact of infection-control measures on MRSA infection rates and determine the morbidity, mortality and economic cost of MRSA carriage on trauma and elective orthopaedic wards.
