Monthly Archives: May 2013
Total knee replacement surgery has been a highly successful procedure for over 30+ years. 90% of patients who undergo the procedure report improved pain relief, knee function and quality of life.
Long term analysis of knee replacements reveal a tendency toward improved implant survival with better/more accurate alignment (positioning of implants relative to the mechanical weight bearing axis of the leg).
Computer assisted surgery (used during the procedure) for knee replacements has been shown to provide more accurate alignment but is associated with increased set-up and procedure time (approximately extra 15-30 minutes).
Efforts to enhance the negative aspects of computer navigation have led to the development of “patient specific” cutting guides. Detailed magnetic resonance imaging (MRI) of the patients knee is obtained preoperatively along with several images of the hip and the ankle. From these images, computer software is used to create and orient in space virtual 3D models of the femur (thigh bone) and the tibia (leg bone). Appropriate implant sizes are determined with the software, and virtual bony resections are mapped that will accomplish accurate position and alignment. A preoperative plan with visual images is sent to the surgeon for review. Upon approval, actual models of the knee are created as well as disposable custom guides that will fit precisely on the patient’s actual bone (femur and tibia) during surgery to determine accurate placement for the standard bone cutting instruments. In this way, total knee replacement can be performed with custom jigs in truly “patient specific” fashion, achieving optimal alignment. Advantages include less surgical time and blood loss. Also, the technique ensures precise sizing of implants and thus a better fit at surgery. The planning is done prior to the procedure rather than in the operating room.
In addition, surgeons still utilize the same tools in the operating room as with conventional knee replacement surgery. Thus, the same checks and balances to obtain accurate bone resections and prosthetic alignment can be performed. Changes from the preoperative planning have rarely been necessary , with now almost 2 years of experience at Jefferson Regional Medical Center.
www.zimmer.com “the right fit for nearly every knee”