Abstract
To compare the new technique of computer assisted knee arthroplasty (CAK) against the current gold standard conventional jig based technique (JBK), 75 consecutive patients underwent knee replacement and were randomly allocated to either the CAK or JBK group. The CAK surgery was performed using a freehand technique that avoids violation of the medullary canal. Pre-and post-operative Knee society scores were collected. Post-operative CT scans were performed according to the Perth CT Knee Arthroplasty protocol and pre-and post-operative Maquet views of the limb performed. Intra-operative soft tissue release together with postoperative pain scores and blood loss were also assessed.
CT scans performed show a statistically significant improvement in component alignment when using computer assisted surgery for femoral varus/valgus (p=0.032), femoral rotation (p=0.001), tibial varus/ valgus (p=0.047) tibial posterior slope (p=0.0001), tibial rotation (p=0.011) and femoral-tibial mismatch (p=0.037). Standing Maquet limb alignment was also improved (p=0.004) as was blood loss (p=0.0001). CAK surgery took longer, a mean increase of 13 minutes (p=0.0001).
This is the first controlled study to assess all seven-alignment characteristics of knee arthroplasty in these two groups of patients.
The improvement in alignment resulted in this trial being stopped prematurely as 6 out of 7 of the initial variables had reached significance. It shows a clear improvement in component alignment with computer navigation. The reduction in blood loss in this surgery through not violating the medullary canal will also be beneficial.
The abstracts were prepared by Mr Tim Briggs. (Editoral Secretary 2003/4) Correspondence should be addressed to him at Lane Farm, Chapel Lane, Totternhoe, Dunstable, Bedfordshire LU6 2BZ, United Kingdom
