CT analysis of defects of the cement mantle and alignment of the stem: in vitro comparison of Charnley-Kerboul femoral hip implants inserted line-to-line and undersized in paired femora.
Using a modern cementing technique, we implanted 22 stereolithographic polymeric replicas of the Charnley-Kerboul stem in 11 pairs of human cadaver femora. On one side, the replicas were cemented line-to-line with the largest broach. On the other, one-size undersized replicas were used (radial difference, 0.89 mm sd 0.13).CT analysis showed that the line-to-line stems without distal centralisers were at least as well aligned and centered as undersized stems with a centraliser, but were surrounded by less cement and presented more areas of thin (< 2 mm) or deficient (< 1 mm) cement. These areas were located predominantly at the corners and in the middle and distal thirds of the stem. Nevertheless, in line-to-line stems, penetration of cement into cancellous bone resulted in a mean thickness of cement of 3.1 mm (sd 0.6) and only 6.2% of deficient and 26.4% of thin cement. In over 90% of these areas, the cement was directly supported by cortical bone or cortical bone with less than 1 mm of cancellous bone interposed. When Charnley-Kerboul stems are cemented line-to-line, good clinical results are observed because cement-deficient areas are limited and are frequently supported by cortical bone.
Scheerlinck
T
T
Department of Orthopaedic Surgery, Academic Hospital of the Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium. Thierry.Scheerlinck@az.vub.ac.be
de Mey
J
J
Deklerck
R
R
Noble
P C
PC
D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D002484:Cementation / Q000379:methods*; D005269:Femur / Q000000981:diagnostic imaging* / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D011474:Prosthesis Design; D011475:Prosthesis Failure; D014057:Tomography, X-Ray Computed