LOW-FRICTION ARTHROPLASTY AT 10 TO 20 YEARS - CONSEQUENCES OF PLASTICWEAR

One hundred eighty-seven patients, in whom 224 low friction arthroplas ties were done by 1 surgeon from 1972 to 1983, were observed for 10 to 20 years. An attempt was made to reassess each patient annually. Pain , walking, and passive range of motion were graded on a 6-point scale (d'Aubigne and Postel assessment). Active movements, straight leg rais ing, and abduction against gravity were recorded in degrees, The avera ge scores, based on 224 assessments done preoperatively, 1914 assessme nts done during the first 10 years, and 590 assessments done during th e second 10 years, were as follows: pain-3.28, 5.71, and 5.59 points; walking-3,34, 5.16, and 4.87 points; passive range of motion-3.42, 4.6 1, and 4.54 points; straight leg raising-40.5 degrees, 60.8 degrees, a nd 54.9 degrees points; and abduction against gravity-8.8 degrees, 24. 3 degrees, and 19.0 degrees points. The percentage of cases with no ce ment-bone interface demarcation based on >2000 radiologic observations was as follows: cup Zone I-9.9%, Zone II-26.4%, and Zone III-26.3%; a nd femoral Zone 1-72.5%, Zone 2-96.7%, Zone 3-94.2%, Zone 4-89.6%, Zon e 5-96.7%, Zone 6-96.3%, and Zone 7-72.6%. A relationship was seen bet ween wear of the socket, and cup migration and revision, development o f femoral endosteal erosions (significant at 95% confidence level), an d femoral prosthesis migration and revision. Ultra high molecular weig ht polyethylene particles that migrate to the cement-bone interface ar e believed to be an important cause of loosening and failure in total hip arthroplasty.