Abstract
Introduction
To utilize existing cancellous bone for initial stability, custom-made stems were implanted without reaming and rasping. This study reviewed the results of this non-reaming technique.
Methods
One hundred and fifty-three hips (138 patients) were followed-up for an average of 12 years (range, 8 to 18). Average age at the surgery was 59 (range, 19 to 78). Seventy percent of the etiologies were dysplastic hips including 17 hips after femoral osteotomy. The Ti-6Al-4V stems were designed using CT data and directly inserted into the femora without reaming and rasping. The stems were coated with hydroxyapatite on the porous coating at proximal 1/3. Harris hip score was used for clinical evaluation.
Results
The average preoperative Harris hip score was 44 points. At the most recent follow-up, the score was 90 points. One hundred and fifty-one hips were evaluated as bone-ingrown fixation and 2 hips were evaluated as stable fibrous fixation. The average subsidence was 0.7mm. Grade 2 or 3 stress shielding described by Engh was observed in nineteen hips. The average cortical ratio of the hips evaluated as severe stress shielding was statistically smaller than that of the hips without severe stress shielding. Osteolysis was observed around the stem in 17 hips.
Discussion and Conclusions
In conclusion, the proximal press-fit of the custom-made stem secured a stable fixation with non-reaming technique. Although the results obtained with the custom-made stem system were excellent over an average follow-up period of 9 years, stress shielding is still an issue.
