Standard anatomical medullary locking (AML) versus tricalcium phosphate-coated AML femoral prostheses.
OBJECTIVE
To compare the preliminary rate and amount of bony ingrowth and calcar resorption between patients receiving either a standard anatomical medullary locking (AML) or a tricalcium phosphate (TCP)-coated AML femoral prosthesis and to compare preliminary clinical results.


METHODS
A prospective, randomized, double-blind clinical trial.


METHODS
An acute care tertiary institution.


METHODS
Between January 1993 and March 1995, 92 patients underwent primary total hip arthroplasty (THA). They were randomized to 2 groups of 46--a control group or a treatment group. Of the 46 subjects enrolled in each group, no significant differences were seen preoperatively with respect to age, sex, diagnosis, clinical and radiographic assessment. Seventy-one patients were followed up for 24 months.


METHODS
Insertion of either a standard AML femoral implant (control group) or a TCP-coated AML femoral implant (treatment group).


METHODS
The degree of hypertrophy, calcar atrophy and the number of spot welds on standard postoperative radiographs at 6, 12 and 24 months. Clinically, assessment according to the Société internationale de chirurgie orthopédique et de traumatologie (SICOT) scale and a 100-point visual analogue scale (VAS) for pain.


RESULTS
There were no prosthetic stem revisions in either group at the 24-month follow-up. Radiographically, bony ingrowth was not significantly different in the TCP-coated stem, by chi2 analysis of the degree of hypertrophy and number of spot welds present. Also by chi2 analysis, the degree of calcar atrophy was not significantly different between groups. The mean VAS score for pain at 24 months was 12.5 for the control and 12.1 for the treatment group. No significant differences were seen in any of the clinical categories of the SICOT Scale over the 24-month interval.


CONCLUSIONS
The objective of TCP-coating--to increase the rate and amount of bony ingrowth while reducing the rate of calcar resorption in non-cemented THA--was not achieved by 24 months postoperatively in our study.
Johnston
D W
DW
Faculty of Medicine and Public Health Sciences, University of Alberta, Edmonton. bjohnsto@cha.ab.ca
Davies
D M
DM
Beaupré
L A
LA
Lavoie
G
G
D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D004311:Double-Blind Method; D005260:Female; D005269:Femur; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D011446:Prospective Studies; D011474:Prosthesis Design; D011859:Radiography
D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; C485817:beta-tricalcium phosphate; C018392:tricalcium phosphate