Abstract
Cementless total hip arthroplasty was introduced into Japan in the mid 1980's and clinical results have been steadily reported since then. However, the condition of the bone around the stem in the years after the operation is not well known.
In this study, a total of 84 patients (90 joints) including 10 males (12 joints) and 74 females (78 joints) treated by total hip arthroplasty using the ceramic coated (with HA/TCP) cementless stem for unilateral or bilateral coxarthrosis were examined. Patients were selected 2 to 6.5 years (mean 4.5 years) passed after the operation. In these cases, laboratory tests were conducted for 2 years after the operation. Roentgenographic findings and bone mineral density were checked at 1 week, 3 and 6 months, and 1 year after the operation. Subsequently, these assessments were conducted at six month intervals until 5years after the operation for bone mineral density and until 6.5 years for roentgenographic findings.
Laboratory test results revealed no local infection or other findings that would contribute to loosening of the stem.
Osteolysis or sinking with time were not observed in the roentgenographic findings for any of the cases. Recovery from femoral atrophy was observed 2 to 2.5 years after the operation with no findings indicative of loosening. Densification, reactive line, and pedestal developed in one to 2 years after the operation. With the passage of time, bone ingrown fixation was observed and fixation of the stem was stabilized.
Bone mineral density decreased for 3 months after the operation in all zones. Recovery was observed after 6 months in zones 3, 4, 5 and 6, after 1 year in zone 1, and after 2 years in zones 2 and 7. These changes preceded morphological changes observed in the roentgenographic findings.
Assessment of changes in the roentogenographic findings and bone mineral density with time in the area surrounding the stem after total hip arthroplasty were very useful for understanding bone condition. Moreover, the postoperative results observed in this study support the safety and stability obtained using this procedure.
