[Periprosthetic bone cement allocation at the femoral durom hip prosthesis. a pilot study: artificial bone models versus ex-vivo femura].
BACKGROUND
Despite controversial discussions, hip resurfacing at the moment seems to be the most bone-sparing surgical procedure of the femoral bone when implanting hip endoprostheses. Main risks are septic and aseptic loosening and necroses of the coxal end of the femoral bone mainly influenced by the periprosthetic allocation of bone cement. Because of a lack of radiation transparency of the hip resurfacing implant, this cement allocation cannot be sufficiently evaluated by common radiological procedures. A pilot study was conducted to describe and validate the macromechanical interdigitation of bone cement with spongy bone of anatomic specimens compared to artificial bone models and to evaluate whether artificial bones may be used for further interdigitation studies of different implantation techniques.


METHODS
Plastic models of polyoxymethylene (POM) according to the inside geometry of the Metasul Durom hip prosthesis were implanted on ex vivo femora (n = 14) versus artificial bone models (n = 24) (Sawbones) of three different spongy densities (0.16; 0.20; 0.32 g/cm(3)) (each n = 8) in a clinically standardised surgical procedure and reproduced by highly resolving computed tomography. Afterwards a computer-based analysis of the cement allocation was accomplished.


RESULTS
It could be shown that the Sawbones of the lower spongy densities (0.16 and 0.20 g/cm(3)) were similar to the ex vivo femora regarding the bone penetration of cement. No significant differences could be shown regarding interdigitation. According to our data, both groups of Sawbones may be used for further studies.
Barbe
A G
AG
Klinik für Orthopädie und Unfallchirurgie, Schwerpunkt Orthopädie, Uniklinik der RWTH Aachen. annagretabarbe@gmx.de
Spennes
J
J
Follmann
A
A
Plumhans
C
C
de la Fuente
M
M
Mumme
T
T
D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001843:Bone Cements / Q000627:therapeutic use*; D015519:Bone Density / Q000502:physiology; D003196:Computer Graphics; D019544:Equipment Failure Analysis; D005260:Female; D005269:Femur / Q000473:pathology*; D006622:Hip Prosthesis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D010865:Pilot Projects; D011183:Postoperative Complications / Q000473:pathology*; D011474:Prosthesis Design; D012117:Resins, Synthetic; D012984:Software; D014057:Tomography, X-Ray Computed
D001843:Bone Cements; D012117:Resins, Synthetic; C010102:delrin