J.-F. Kempf , Ph. Gicquel (Strasbourg)
Comparative study of the clinical résults of a TKA cruciate retaining with fixed or mobile bearing
In a retrospective study we compared the results of ISA (with mobile bearing PE) versus Standard (fixed PE) Interax cemented total knee arthroplasty (Stryker ®).
30 cases of ISA TKA performed in 1997 were reviewed with a minimal follow-up of 5 years, and we compared them to a matched group (concerning the principals criteria : follow-up, age, sex, preoperative scores) of 30 Standard TKA performed before 1997.
In the postoperative period 1 mobilisation under anesthesia for stiffness was necessary in the ISA group, which also showed a lower (non significant) range of motion at discharge with 95° vs 97° for the Standard group.
At a mean follow-up of 66 months, there were 3 mechanical complications (2 femoro-tibial and 1 patellar dislocation) in the Standard group, requiring revision and none in the ISA group. The scores were close but the range of motion was still lower (non significant) in the ISA group with 103° vs 107° in the Standard one. Concerning the radiological results, we didn’t observe any radiolucent lines in the ISA group whereas 3 cases (with 1 case exceeding 2 millimetres) were observed in the Standard one.
Concerning the mobility of the PE of the mobile bearing, a RSA study was done by the German team of the Interax group who demonstrated the reality of the mobility of the PE.
In conclusion, the results are close but if Standard TKA seems to be better for the mobility, ISA probably preserve the anchorage if we accept a filiation between lucent lines and loosening. Concerning polyethylene wear, we can’t conclude but we didn’t observe any polyethylene dislocation in the ISA group. Concerning the flexion, a mobile bearing WITH conservation of the PCL is not able to procure a deeper flexion and the interest of a postero-stabilized mobile TKA will be discussed.