Bilateral simultaneous total knee replacement surgery remains controversial with arguments for and against its use. Doing sequentially staged TKR's is a safer procedure and may have additional benefits as set out below. If both knees need to be replaced we have often seen that the symptoms of the contralateral knee improve after the one knee is replaced and that patients wait some time before having the opposite knee replaced. 333 of 2084 patients having primary total knee replacements needing bilateral replacements were reviewed retrospectively. 245 patients were seen initially with bilateral arthritis of the knee and needed bilateral TKR, while 88 patients developed arthritis in the contralateral knee following TKR. No patients had simultaneous bilateral TKR's; operations were done sequentially and the average time between the TKRs was 20.77 months with a range between 1.5–111 months. Most patients had the contralateral knee replaced within two years of the first knee replacement but 81 patients actually waited between 2 and 10 years before coming in for the second TKR.Materials:
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At the 2010 Effort congress Prof Hernigou of France stated that you never need to template knee x-rays as there is an absolute association with patients height and implant size. Templating of the knee for size is seldom done in clinical practice but could be handy when doing revision surgery where normal anatomy has been lost. This is however difficult with digital x-rays due to enlargement problems. With this in mind we retrospectively looked at the size of knee implants inserted to see if there was any relation with patient's height and also to see if this differs in male and female patients. 2084 IB II and NexGen knee replacements were reviewed from our database and implant size was correlated to patient height.Material:
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Digital x-rays on computer screens are difficult to template due to the lack of standardized magnification. This can be overcome by the use of markers placed onto or next to the patient but have certain shortcomings. Trochanteric marker placements are operator dependant and very difficult to use in the obese patient. Inter- thigh markers are also operator dependent and often embarrassing for radiographer and patient. Anterior combined with posterior markers are very accurate (King et al) but can only be used with a digital template system which is costly and time consuming. We would like to describe a new method of posterior bar markers that are easy to use with standard hip templates. Over a period of 30 months this method of templating was used on 296 primary total hip replacements. Fifty eight patients had a previous hip replacement with known head diameter which was used as a control to assess the accuracy of enlargement with this method. X-rays were taken of each patient as a standard supine AP of both hips with the patient lying on a marker ruler with 30mm metal bar markers. The X- rays are then loaded onto a PACS digital x-ray system for use in theatre. In theatre the X-rays are enlarged until the 30mm bar markers are enlarged to 31mm on a standard ruler which represents a 20% (as seen in patients with contralateral hip replacements) enlargement of the hip and standard 20% enlarged plastic templates can then be used to measure the neck resection level and assess implant size and offset. The patients with previous contralateral hip replacements were used as controls to evaluate the accuracy of this method by correlating the head size on the enlarged x-ray with the 20% enlarged ruler on the template.Introduction
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