Between 1986 and 1991, 106 patients (127 knees) underwent uncemented knee arthroplasty for osteoarthritis. There were 106 total knee arthroplasties and 21 medial unicompartmental knee arthroplasties. The arthroplasties were evaluated for aseptic loosening during the year 2000. For total arthroplasty we used 77 porous-coated anatomic prostheses and 29 press-fit condylar prostheses. The mean bone mineral content of the proximal tibia, measured the day before surgery using dual-photon absorptiometry was 5.48 g/cm for the porous-coated anatomic prostheses which were revised for aseptic loosening (n = 9). This was significantly higher (p = 0.02) than the mean of 4.33 g/cm for those which were not revised. Values for the two revised press-fit condylar knees (4.78 and 4.93 g/cm) were above the mean value (4.23 g/cm) for those which were not revised. We found no statistically significant (p = 0.38) difference between the bone mineral content of the 12 revised and nine unrevised unicompartmental arthroplasties. Low trabecular bone quality, measured as the pre-operative bone mineral content of the proximal tibia, was not a predictor for later revision surgery following uncemented total knee or unicompartmental knee arthroplasty.

The short-term survival after an ITPIE was similar to that of a total knee revision with exchange of all components. Since the ITPIE is a much smaller operation with fast rehabilitation, we recommend it in elderly patients with a well-fixed and wellaligned prosthesis without surface damage of the components.

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Background Bioactive coating of uncemented total knee arthroplasty (TKA) is believed to increase bone ingrowth and enhance early fixation of the TKA. In a prospective randomized study using radiostereometric analysis (RSA) we examined migrations of the tibial implant, in an uncemented TKA with and without bioactive coating. The study was performed according to new RSA guidelines, and focus was put on some important methodological issues. Materials and methods Twenty-three patients with osteoarthrosis of the knee received an uncemented Duracon TKA either with bioactive (hydroxyapatite or periapatite) coating (+HA) or without bioactive coating (-HA). Patients had RSA examinations postoperatively and at 3, 6 and 12 months. Nine patients were excluded during the study resulting in 14 knees for final analysis. Results At 12 months follow-up we found no significant differences in migrations between the two groups. However, in general the -HA group migrated more than the +HA group, and we found a significant larger variation in migration pattern in the -HA group. In the +HA group the tibia component stabilized after 6 months, whereas the -HA group showed continuous migration. Subsidence and posterior tilt were the main migration patterns in both groups.Conclusions Bioactive coating of TKA seems to enhance early stabilization of the tibia component. Similar results are found in previous studies.