NATURAL-HISTORY OF FEMORAL FOCAL OSTEOLYSIS WITH PROXIMAL INGROWTH SMOOTH STEM IMPLANT

Focal femoral osteolysis has become a prominent cause of failure of to tal hip arthroplasty. Femoral focal osteolysis is studied in 185 hips with a parched porous-coated titanium Femoral stem. Seventy-two hips h ad osteolysis and 113 did not. Seventy-one percent of osteolysis is ev ident on radiographs by 6 months to 5 years after surgery. The locatio n is most commonly seen on an anteroposterior radiograph, with proxima l osteolysis most common and the initial size of defects being greates t in zones 2, 3, 5, and 6. Progression of size is slow with each focal defect averaging 0.89 mm/y. Progression of bone loss occurs more comm only with the occurrence of new defects rather than extension of an ex isting defect. Focal osteolysis was directly correlated with the amoun t of polyethylene wear. Osteolysis is more likely when linear polyethy lene wear exceeds 0.2 mm/y or volumetric wear exceeds 150 mm(3)/y or w hen the patient is below age 60. Accelerated wear and osteolysis occur most often when the fixation of the arthroplasty is poor.