Although long-term studies of total knee arthroplasty(TKA) have confirmed reliable relief of pain and maintenance of function, survivorship at nine to ten years has been inconsistent with late component loosening being the most frequent mode of
failure. Tibial component failure has been more frequent than failure of the femoral or patellar component in most TKA series. Encouraged by the early results of porous-ingrowh femoral and patellar components, and aware of retrieval studies
showing
poor
bone ingrowth into tibial components, the "hybrid" method of fixation with an uncemented femoral component and a cemented tibial component, has been introduced and incorporated the potential advantages of both traditional fixation techniques.
Between January 1987 and December 1991, forty-five "hybrid" TKAs(group I) were performed in degenerative arthritis and evaluated retrospectively in comparison with the results of nineteen nonce-mented porous-coated TKAs(group II) in degenerative
arthritis. The average follow-up period was 31 months(range, 14 to 60 months) in group I and 26 months(range, 13 to 63 months) in group II. Using the knee rating scale of the Hospital for Special Surgery and the American Knee Society
Roentgenographic
Evaluation and Scoring System, clinical and radiological comparative study between two groups was performed.
Pain scores, range of motion and HSS knee scores improved in both groups, but there was no significant difference between group I and group II(p<0.05). In both groups, the scores of radiolucent lines were significantly higher in zone 1 and 4 of
A-P
roentgenograph of the tibial component than in other zones(p<0.05). The tibiofemoral angle was corrected from valgus 2.7°to valgus 5.8° in group I and from varus 3.4°to valgus 4.6°in group II. There was no significant differences in component
position and scores of radiolucnet lines between group I and group II.
In conclusion, there were no significant differences in clinical and radiological results between the "hybrid" and the cementless groups. Results of this study suggest that both the hybrid fixation and the comentless techniques can reliably
provide
satisfactory clinical and radiological results in properly selected degenerative arthritis patients. But the final outcomes of this study need further evaluation through long term follow-up.
|