The effect of diaphyseal biologic fixation on clinical results and fixation of the APR-II stern

This study evaluated the effect of a grit-blasted diaphyseal surface on non cemented fixation of the Anatomic Porous Replacement II stem (APR-II, Sulze r Medica Orthopaedics, Austin, TX) for improvement of clinical results and fixation. A total of 107 consecutive total hip arthroplasties with the APR- II stem, which has proximal porous coating and a diaphyseal grit-blasted su rface, were performed without cement, and 99 were studied at average 4 year s. Of these hips, 37 had hydroxyapatite sprayed onto the proximal porous co ating, but because there were no statistical differences for performance in any category, all stems were considered as 1 group. Clinical results were measured by the Harris hip score. Radiographic measurements of fixation. os teolysis. and bone remodeling were studied by reference to Gruen zones. Of hips, 99% had a good or excellent result by Harris hip score, with an avera ge pain store of 42.3. Of hips, 98% had >40 points, with no patient reporti ng thigh pain after 3 years. There were no radiolucent lines in 94% of stem s, and 100% had proximal bone ingrowth fixation. Distal cortical hypertroph y associated with tip fixation occurred in 49%. whereas proximal stress shi elding was present in 43% of hips. Comparison of these clinical and radiogr aphic results with our previous experience of hone ingrowth implants (smoot h stem) suggests that bone ingrowth proximally with ongrowth in the diaphys is of the femoral stem provides better clinical and radiographic results.