Radiographic analysis of an investigational hydroxyapatite-coated total hip replacement.
OBJECTIVE
The impetus to discover cementless techniques for fixing implants to bone is the result of the high failure rates of cemented arthroplasty in young, active patients. The application of hydroxyapatite (HA) to implants represents an alternative. The purpose of this investigation is to define the early radiographic pattern of an HA femoral stem and compare this definition with an identical stem without the HA treatment.


METHODS
Radiographic analysis was performed on 98 hips: 63 HA stems and 35 non-HA stems, with a 1-year follow-up. Radiographic parameters analyzed included: 1) radiolucent line formation; 2) endosteal bone formation; 3) calcar response; 4) periosteal bone formation; 5) heterotopic bone formation; 6) stem subsidence; and 7) quality of fit.


RESULTS
The HA stem demonstrated greater proximal endosteal sclerosis and distal radiolucency (P < .001). The non-HA (control) stem demonstrated greater proximal and distal radiolucency (P < .02) and distal endosteal sclerosis (P < .001).


CONCLUSIONS
The HA pattern suggests proximal load transference and bony fixation. The control pattern suggests distal loading and fixation, in addition to motion between the stem and native femur. These patterns indicate an advantage of the HA fixation over traditional implants.
Abrahams
T G
TG
University of Vermont School of Medicine.
Crothers
O D
OD
D000328:Adult; D000368:Aged; D017886:Durapatite; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D006882:Hydroxyapatites; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D011859:Radiography; D013499:Surface Properties
D006882:Hydroxyapatites; D017886:Durapatite