Newer Techniques

Newer techniques increasing in popularity

Gap balancing techniques
Nearly every step of the procedure requires consideration of bone alignment and soft tissue tension, both of which are critical to success.  One attempts to remove the minimal amount necessary.  The size of the implants must be accurately accessed to match the size of the native knee.  The “joint line” must be re-established to match that of the native knee.  Lastly, the tension on the ligaments must be recreated.  Too little tension can lead to painful instability patterns. Too much tension on the ligaments can produce a stiff and painful knee.  “Gap balancing” techniques make ligament tension a primary concern when choosing implant position. 

Computer-generated cutting blocks
Based on a preoperative MRI or CT scan, individualized cutting blocks are manufactured to fit the patient’s anatomy.  It has yet to be demonstrated that this technology will improve implantation accuracy, though low volume knee replacement centers may benefit.
 
Intra-operative computer navigation
Using selected boney prominences; a computerized navigation system constructs a virtual knee joint.  This information is then used to guide the surgeon for accurate sizing and placement of the prosthetic components.  Published studies generally support the increased accuracy afforded by this technique.

Robotically guided implantation
Using selected boney prominences, a computerized navigation system constructs a virtual knee joint and a robotic arm performs the bone resection, guided by the surgeon (www.mako.com). High degrees of accuracy have been demonstrated.  This technique is available for partial knee replacement only. 

Customized computer-generated prosthesis

This should not be confused with computer-guided implantation.  The manufacturer, Conformis, produces the only computer-generated total joint prosthesis.