100 randomized primary cementless THRs in 80 patients were reviewed retrospectively regarding the HA cover of the stem which was Waldemar Link’s, ribbed type, made of Titanium, with a collar and mostly applied without the trochanteric screw. The femoral neck was always retained high as possible. Full weight bearing on the operated leg started the 3rd postoperative day, while years earlier the 6th postoperative week. Two more or less, equal groups were formed: (A) without, (B) with HA covered stems and two subgroups: patients of 60 to70 years and 70 to 80 years. Gender was matched as possible and mean follow-up time was 8 years (range 7 to IO years). The Harris Hip Score was used for clinical evaluation and the method of “pencil and ruler” in plain X- Rays for radiographical one. Patients who died after the 8th postoperative year of evaluation were included. Results 1, The postoperative hip score was at average for group (A) 92.1 points and for gr. (B) 92,4p. 2. In gr. (A) we found* at a rate 70% 2mm of symptom less, adaptive, slow early migration, while in gr. (B) this corresponded to 1 mm of same migration at a rate 60%. In both groups migration stopped by the second postoperative year. 3. “Alarming” stem migration was found in two cases: one in each group. The cause was that the stems applied, were undersized and the patients were women on menopausal osteoporosis. Both sterns were revised. Two more “alarming” stem migrations were found, one in each group, in patients suffering from collagenosis with the relevant bone quality. This migration was related to bone retreat primarily and irrelevant to stem’s loosening, gender or age of patients. Both stems have not been revised yet. 4. Similar and minimal-2% for gr. (A) vs 4% for gr. (B)- was the rate of symptomless, limited, non-sclerotic of less than 2mm wide demarcations gradually resolving, 5. Similar and minimal-2% for gr. (A) vs 5% for gr (B)- was the rate of stress shielding phenomenon resolving in 2 years time. 6. No further mechanical or biological loosening were noticed at mid-term results 7. Similar- 20% for gr (A) vs 15% for gr (B) was the rate of mild symptomless ectopic ossifications.
