The aim of this prospective single-centre study was to assess the difference in clinical outcome between total knee replacement (TKR) using computerised navigation and that of conventional TKR. We hypothesised that navigation would give a better result at every stage within the first five years. A total of 195 patients (195 knees) with a mean age of 70.0 years (39 to 89) were allocated alternately into two treatment groups, which used either conventional instrumentation (group A, 97 knees) or a navigation system (group B, 98 knees). After five years, complete clinical scores were available for 121 patients (62%). A total of 18 patients were lost to follow-up. Compared with conventional surgery, navigated TKR resulted in a better mean Knee Society score (p = 0.008). The difference in mean Knee Society scores over time between the two groups was not constant (p = 0.006), which suggests that these groups differed in their response to surgery with time. No significant difference in the frequency of malalignment was seen between the two groups.

In summary, computerised navigation resulted in a better functional outcome at five years than conventional techniques. Given the similarity in mechanical alignment between the two groups, rotational alignment may prove to be a better method of identifying differences in clinical outcome after navigated surgery.

Since 2000 we have performed TKR with the aid of a computer assisted navigation system (PiGalileo). Over this time we have made more than 2000 TKR, while continuing to monitor results from both standard technique and computer navigated TKR.

As we began to work with the computer assisted navigation system, we ran a comparison trial to ascertain the accuracy of mechanical axis calculation. The trial comprised of 32 patients. The accuracy of the calculation in both techniques was measured by paralax-free X-ray. The computer assisted navigation group showed a deviation of 0.9°–2.5°, whereas the standard technique group showed a deviation of 3.5°–4.6°.

A second comparison was conducted involving 186 patients. The TKR were performed from August 2000 to December 2001. All patients received the same implant (TC-Solution). All operations were performed by the hospital’s two most senior surgeons. Cases involving deviations from our standard TKR (such as patellar replacement) were eliminated from the trial. Two groups were created randomly:

Group A (88 patients) standard technique

All patients were examined by an independent doctor, in accordance with a clearly defined protocol. Preoperative and postoperative clinical examinations with X-rays were made. Check ups with valuation of the KSS score (Insall) and HSS Knee score (Ranavate and Shine) followed after 3,6,12,24 and 60 months.

Both groups have comparable biometric data. In the post-surgery checks we found noticeable differences in the axis positions of the legs and the ventral cutting plane in favour of group B. This group showed better clinical results and patient satisfaction.

There was no difference in the outcome in case of retropatelar problems, as the first generation software did not permit rotation assessment of the prosthesis. The current version of the system allows this assessment.

The results of our clincal observations confirm the advantage of computer navigated TKR. It has become our standard operating method. The navigation system is reliable, warrants better axis and rotation positioning of the prosthesis; exact cutting planes, and consequently, exact setting of the implants. Through progressive development of the navigation system and refined surgical techniques in relation to computer assisted TKR, we have reduced the average TKR operating time.