Proximally versus fully porous-coated femoral stems: a multicenter randomized trial.
There are two broad-based categories of cementless femoral component designs: proximally porous-coated and fully porous-coated. While both have been widely used, there remains debate regarding differences in clinical outcome scores, relative incidence of thigh pain, and development of stress shielding. We investigated these variables in a multicenter prospective randomized blinded clinical trial of 388 patients from three centers: 198 patients had a proximally porous-coated tapered cementless femoral component and 190 patients had a fully porous-coated cementless femoral component. A minimum followup of 2 years (mean, 6.7 years; range, 2.0-8.65 years) was available in 367 of the 388 patients (95%). We observed no differences in age at surgery, body mass index, or preoperative clinical outcome scores (WOMAC, SF-12, Harris hip score, UCLA activity, thigh pain) with the two groups. We determined serial bone density changes in a subcohort of 72 patients from two of the three centers. The postoperative clinical outcome scores were similar at all followup intervals, and we observed no differences in the incidence of thigh pain at any time. Bone density reduction in Gruen Zone 7 was greater with the fully coated stem than the proximally coated stem (24% versus 15% reduction, respectively). Both fully and proximally coated stems performed well, with no clinical differences at 2 years' followup, except in bone mineral density evaluations.


METHODS
Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
MacDonald
Steven J
SJ
London Health Sciences Centre, University of Western Ontario, 339 Windermere Road, London, ON, N6A 5A5, Canada. steven.macdonald@lhsc.on.ca
Rosenzweig
Seth
S
Guerin
Jeffrey S
JS
McCalden
Richard W
RW
Bohm
Eric R
ER
Bourne
Robert B
RB
Rorabeck
Cecil H
CH
Barrack
Robert L
RL
D015502:Absorptiometry, Photon; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation*; D015519:Bone Density; D002170:Canada; D020099:Coated Materials, Biocompatible; D004311:Double-Blind Method; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery*; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008145:Louisiana; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology / Q000517:prevention & control; D010147:Pain Measurement; D016062:Porosity; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D020127:Recovery of Function; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D016896:Treatment Outcome
D020099:Coated Materials, Biocompatible