Osteolysis after TKA - About 9 cases in a serie of 122 Posterior Cruciate Retaining Prosthesis

Purpose of the study The aim of our work was to study X-rays showing osteolysis after 5 years an d more in 122 prosthesis and to try and assess such complication, often des cribed in the United States but seldom in Europ. Material We are dealing here with 122 retaining posterior cruciate ligament, mostly cementless prothesis implanted between 1985 and 1992 84 chromium-cobalt pro sthesis (PCA and Themis) implanted in 34 males and 88 females with an avera ge age of 67 (45-81), 87,7 p. 100 had femoral cementless components and 70 p. 100 tibial cementless components. Methods All patients were examined and had X-rays at an average of 6,9 years. Speci ally considered were X-rays showing a possible osteolysis, We looked for po ssible complication (external laxity, anterior femoral dislocation and poly ethylene wear), assessment of the mechanical axis and for clinical results (Hungerford score) Results Revisions: 19 arthroplasties were revised for PE wear (3) tibial loosening (6) metallosis (6) or patella problems(4) The postoperative score according to Hungerford was 84,5 p. 100 for PCA prosthese and 87 p. 100 for the Them is. On the X-rays were only few osteolysis to be found: 9 cases (7,3 p. 100 ). For the PCA series: 3 femoral osteolysis, 1 tibial at 12 years, and one patellar osteolysis. For the Themis series: no femoral osteolysis, 3 tibial and one patellar osteolysis. Osteolysis are apparent on X-rays in profile for the femur and the patella, and in both profile and frontal X-rays for t he tibia. Clinicaly 4 osteolysis really asymptomatic were not re-operated. 5 were rev ised: one 11 years later for femoral and tibial loosening, two for a patell ar loosening, the other two patients had to be reoperated on tor metallism (titanium's femoral component) and for those two instances osteolysis were discovered during the complication. Discussion Osteolysis after TKA appears unusual in our experience without bearing on f requency finded by american authors with a lesser follow-up (Engh 11,1 p. 1 00 after 4,5 y, Peters 16 p. 100 after 2,9 y, Robinson 9,18 p. 100 after 4, 6 y). American litteratur analysis shows that the important number of osteolysis is due to: - either to dual-metal using (Co-Cr component with Titanium scre ws for exemple), - or bad quality of polyethylene (compressed), - or a bad design of former prosthesis. Conclusion Interface illness, linked to the production of wear debris, osteolysis afte r total knee arthroplasty is rarer than after a hip one, probably because s ize of debris is different, larger in knee than in hip.