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Better Fit for Total Knee Replacement with Computer Assisted Templates

Total knee replacement (TKR) is a common operation these days. The success of this procedure depends on surgeon skill and planning. Bone shape and size are slightly different for every patient. So bone cutting and aligning the implant are especially important.

In this study surgeons practice a new way to line up the implant using a 3-D computer program. Plastic and cadaver knees are used first before this idea is tried out on live patients.

Before the operation a model or template of the patient's knee was made using 3-D CT scans. In this way an exact or very close implant match could be made. Using the computer program gave surgeons a chance to move the implant until the desired alignment was obtained.

This program helped the surgeons avoid over rotating the femoral implant, a common problem during TKR. They could carefully plan out ahead where and how to make the best cuts into the bone.

Using the virtual templates cutting blocks were made to match each knee's unique shape. Results of the computer-assisted TKRs were compared to standard TKRs. The authors report smoother cuts into the bones and smaller gaps between the bones and implants with the templates.

Patient-specific templates are superior to standard instruments used. This new method was easier, faster, more accurate, and less expensive compared to the usual method used. The authors list several problems that still must be solved before this technique can be used on humans. More studies are needed to improve this method.

References: M. A. Hafez, FRCS (ED), et al. Computer-Assisted Total Knee Arthroplasty Using Patient-Specific Templating. In Clinical Orthopaedics and Related Research. March 2006. No. 444. Pp. 184-192.

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