PURPOSE OF THE STUDY

The authors present the results of their first trial of a new, Beznoska / S. V. L. type, knee prosthesis in order to introduce   it to a broad orthopedic public.

MATERIÁL

Clinical and radiological evaluation was carried out on 34 knee prostheses implanted in 31 patients between Septem-ber 1997 and October 1999. The average patient age at the time of surgery was 71.3 years and the average interval bet­ween surgery and assessment was 22.4 months (range 6 to 31 months). All patients underwent implantation due to pri-mary or secondary gonarthosis. A brief desription of the implant and the instrumentation and ušed surgical technique is provided.

METHODS

Clinical outcomes were evaluated according to the "Knee-Society Clinical Rating System" by John N. Insall. The systém classifies both knee joint parameters and knee function. X-ray films were assessed on the basis of the "Knee-Society To­tal Knee Arthroplasty Roentgenographic Evaluation and Scoring System" by Frederic O Ewald. In standardized X-ray pro-jections, this allowed us to evaluate the implant position as well as radiolucent lineš.

RESULTS

On stability evaluation, we found anteroposterior instabilíty up to 5 mm in 85 % of the implants and mediolateral insta-bility up to 9° in 97 % of them. A maximum flexion of 90° to 120° was achieved in 91 % of the implants. The finál outcome in terms of knee score was on average 80.3 points (range, 40 to 97 points), which was a very good result.

Evaluation by function score showed that only 17 % of the patients were not able to walk farther than 500 meters. Alt-hough 82 % of them had to hold on a railing when going upstairs, all were able of stair ascent and descent; 13 % had to use a walking stick permanently. The average function score was 68.4 points (range, 30 to 100), which was a good out­come.

Radiograms in anteroposterior projection, assessed according to Ewald, showed the average femoral flexion angle (a) to be 95.2°, the average tibial angle (p) to be 89° and the total valgus angle (co) to be 3.2°. In lateral projection, the femo­ral flexion angle (7) was on average 2.5° and the average tibial angle (S) was 86.7°. An optimal position of the patella was achieved in 27 implants. Five radiolucent Unes, up to 1 mm, were found in zone 1 of the femoral component and further li­neš were observed in zones 1, 2 and 4 of the tibial component.

DISCUSSION

When assessing the results by the knee and function scores, it had to be taken into consideration that the average age of the patients was 71.3 years. At this age, walking without a stick, or stair ascent or descent without the use of a railing can hardly be expected. The average result of 68,4 points achieved can, therefore, be considered a very satisfactory out­come. The values shown by X-ray examination were close to the normál condition. The patients were also asked for their subjective opinion of the effect of arthroplasty; 97 % of them regarded the effect as good or very good, only one patient reported no benefit.

CONCLUSIONS

The results of the first trial of the use of a cemented prosthesis, type Beznoska / S. V. L, in total knee arthroplasty are presented, together with practical recommendations. Although the patient sample was small and the follow-up period short, the results are promising and suggest excellent prospects for this implant.

Key words: total knee arthroplasty, radiography, knee score, function score.

Celý článek ke stažení zde:

První zkušenosti s implantací cementované totální endoprotézy kolenního kloubu typu Beznoska / S. V. L. 357.0 KB