Abstract
The ROCC® prosthesis is a stabilised posterior cruciate ligament-sacrificing rotating mobile bearing knee. It contains a press-moulded polyethylene insert (Arcom®). It has high coronal conformity during gait and lift-off, and sagittal conformity during the weight-bearing phase. It also has a central concave-convex saddle-horse stabilisation mechanism with a progressive stop. Preferential gliding kinematics optimise the wear factor. A deep anatomical trochlea permits good patellar tracking at every degree of flexion with both resurfaced and unresurfaced patellae. The tibiofemoral displacement of the prosthesis approximates normality.
In 175 primary TKAs with the ROCC® knee, at two-year follow-up the objective measurement of pain was 8.7 out of 10 (7 to 10) in 94% of patients. In 89% of patients, the range of flexion was 128° (95° to 145°). At 3 months, the Knee Society Score was 175 in 87% of patients (function score 80), at 6 months 185 in 89% of patients (function score 90) and at 12 months 200 in 94% of patients (function score 100).
In 98% the femoral component was not cemented and there were no femoral radiolucent lines. The tibial component was not cemented in 30% and two patients in this group needed revision for loosening of the tibial plateau. There were no complications such as persistent pain, flexion contracture, Sudeck’s syndrome, instability or dislocation. Mechanical tests did not show any wear or cold flow deformation of the polyethylene insert after 3 million cycles.
The abstracts were prepared by Professor M.B.E. Sweet. Correspondence should be addressed to him at PO Box 47363, Parklands, Johannesburg 2121, South Africa.
