The Finnish Arthroplasty Register was established in 1980. Between 1980 and 1999, 62,841 primary and 12,224 revision total hip arthroplasties (THA) were recorded. The annual number of both primary and revision THA has increased: in 1999, the incidence of primary THAs was 93/100,000. 174 implant designs have been used, but the 6 commonest implants comprised 82% in 1999. Since the late 1980s, more than 40% of the hips were inserted without cement. Over 47% of the cementless primary hip prostheses were used in patients younger than 60 years and over 93% of the cemented primary hips were used in patients 60 years or older. The 10-year survival rate was 72 (95% CI 67-76)% in patients younger than 55 years and 90 (89-91)% in patients older than 70 years. The commonest reasons for revision were aseptic loosening (65%), dislocation (9%) and infection (7%). In revisions, the 5-year survival of the cementless hip prosthesis improved over time: it was

We measured the post-operative radiological "fit and fill" of two different femoral stem designs, one with a straight proximally porous-coated n=50) and the other with a proximally anatomic, hydroxyapatite-coated and distally over-reamed stem (ABG, n=26). A comparison was then made between the clinical and radiological 5-year follow-up data of these two series and also of the bone remodeling changes around the stems. The observed differences in "fit and fill" parameters in the metaphyseal region were minute. However, in the diaphyseal bone the straight stem had substantially more cortical contact. The clinical results were excellent for both groups. Subsidence (>2 mm) was more frequent with the anatomical ABG stems, although the ABG stems had better bone ingrowth in the lower metaphyseal area. The present results indicate that the anatomical design may improve the fit and fill of a femoral stem in the metaphysis. On the other hand, a looser fill of the diaphyseal bone made the stems of this type more susceptible to subsidence. The straight stem with tight diaphyseal fit showed excellent stability, but the good bone ingrowth and remodeling around the distal part of the stem indicates stress transfer through this region and increased stress shielding of the proximal metaphyseal femur.Résumé Nous avons mesuré l'adaptation et le remplissage radiographique postopératoire de deux modèles diffé-rents de tiges fémorales, une tige droite avec la porosité proximale (BI-Metric, n=50) et une tige proximalement anatomique revêtue d'hydroxyapatite avec un surfaçage distal (ABG, n=26). Nous avons comparé les renseignements cliniques et radiographiques de ces deux séries de données résultant d'un suivi de cinq ans. Le remodelage osseux autour des tiges a été pris en compte. Les diffé-rences observées dans les paramètres de l'adaptation et de remplissage dans la région métaphysaire étaient minimales. Par contre dans la région diaphysaire la tige droite faisait montre de plus de contact cortical et ceci d'une manière significative. Les résultats cliniques sur ces deux groupes furent excellents. L'enfoncement (>2 mm.) de tiges anatomiques ABG était plus fréquent. Les résul-tats présentés indiquent que le modèle anatomique pourrait améliorer l'adaptation et le remplissage de la tige fé-morale dans la région de l'os métaphysaire.

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Wear of the socket liner and resulting osteolysis are the major causes of failure in cementless hip arthroplasties. We report alarming wear of the first-generation polyethylene liner of the cementless porous-coated Biomet Universal cup. Radiographs of 107 primary hip arthroplasties were analyzed retrospectively. The mean follow-up time was 74 (47-91) months. The linear wear of the polyethylene liners was assessed using a modification of the Livermore method. The median linear wear was 1.0 (0-6.2) and the median linear wear rate was 0.17 mm/year. There was a statistically significant difference between the 28 mm and 32 mm femoral head groups both in the volumetric wear and in the volumetric wear rate. The median linear wear was 0.28 mm/year and 0.14 mm/year for the 32 mm and 28 mm heads, respectively. So far, 14 revisions have been performed or have been scheduled because of excessive wear of the polyethylene liner. In regression analysis, the factors related to the wear rate were the 32 mm size of the femoral head and screw fixation of acetabular shell. We found that the cases with calcar rounding were associated with significantly greater wear. Possible reasons for increased wear of the Hexloc liner may be the cylindrical design, thin polyethylene, and poor quality of the polyethylene. Regular clinical and radiographic follow-ups are recommended especially for hips with 32 mm femoral heads or with screw fixation. If progressive wear of the liner is observed, revision must be considered.