Laurent Sedel, Steeve Sulimovic(Paris)
Mobile bearing knees are well known. This current study deals with a special design with fully constraint contact and full mobility of the bearing. 89 prosthesis were introduced prospectively and consecutively in 81 patients, 70 females and 11 in males. Mean age was 74 years. 7 knees has been already operated (5 osteotomies and one unicondylar). Patients were followed from periods from 75 days to 15 years (median 8,4 years).
Results were evaluated by an independent observer. Clinical evaluation, X-rays in patients that did show up and satisfaction. Twenty three patients deceased with their prosthesis. There was 21 revisions: five for traumatic fracture, one for sepsis after a haematoma, and 9 for loosening (5 tibias, 2 femur, and 2 patella). Survivorship taking revision of total joint related to loosening or pain as event was 81% @ten years. Survivorship taking full revision (excluding patella) as an event was 91%. Among the revision, 2 concerned knees already operated (one osteotomy and one unicondylar prosthesis). Pain improved markedly, mean range of flexion was 117°. 66. Mean oxford score was 22, 52; mean HSS score was 87; mean KS score was 196.
No or very limited positive drawing test were recorded. Although this is not a randomized controlled study, this fully constrained prosthesis with mobile bearing knee is interesting: range of motion is important and revision events were not superior to other designs. Limitation of polyethylene wear debris related to the fully conforming design could possibly allow a better long term survival.