Comparison of Proximal Porous-Coated and Grit-Blasted Surfaces of Hydroxyapatite-Coated Stems

Background: It remains controversial whether a proximal porous coating is superior to a grit-blasted surface with regard to providing femoral stem fixation in total hip arthroplasty. We examined the hypothesis that a proximal porous coating would provide better fixation than would a fully grit-blasted surface of otherwise identical proximally hydroxyapatite-coated stems.

Methods: In a prospective study, seventeen patients (thirty-four hips) underwent bilateral sequential total hip replacement with the Anatomic Porous Replacement at the same operation. A proximally porous-coated femoral stem was implanted on one side, and a stem of the same design but with a proximal grit-blasted surface was implanted in the contralateral hip. A proximal hydroxyapatite coating was applied to the metallic substrate of both stems. The patients were followed for a mean 2.5 years and then were assessed radiographically and clinically with the Harris hip score.

Results: With the numbers available, no significant clinical or radiographic differences were found between the two cohorts. Thirty of the thirty-four hips had an excellent result, two were rated good, and two were rated fair. All hips had stable osseous fixation of the stem radiographically. The two types of stems were associated with the same pattern of adaptive bone-remodeling.

Conclusions: In the first two years following total hip arthroplasty, hydroxyapatite-coated proximally porous-coated femoral stems do not provide fixation that is superior to that provided by hydroxyapatite-coated grit-blasted stems.

Level of Evidence: Therapeutic study, Level II-1 (prospective cohort study). See Instructions to Authors for a complete description of levels of evidence.