[Radiological analysis of osseointegration after implantation of the Zweymüller-Alloclassic total hip system].
OBJECTIVE
The purpose of this study was to identify typical radiological patterns of osseointegration following implantation of the Zweymüller-Alloclassic total hip system.


METHODS
The follow-up included the clinical and radiological evaluation of 115 consecutive hips. For each case the screw direction of the cup was calculated individually to fully observe the bony surroundings by properly tilted X-ray beam.


RESULTS
After 8.1 years, the Harris hip score was 88.5 points on average. Trabecular condensations leading toward the threads of the cup were observed in 100 cases, underlining the importance of the threads for load transfer. A complete intrusion of the threads into the pelvic bone was not accomplished in 23 cases with marked sclerosis of the acetabulum. The reduced connection, however, did not impair stability or function. The area of the distal stem is characterized by cortical hypertrophy and trabecular condensation of the neighbouring marrow. Linear radiolucencies were frequently observed in Gruen-Zone 1 and 7, in 5 cases extending into zone 2 and 6 without influence on the clinical function of the implant.


CONCLUSIONS
Material and geometry of the Zweymüller total hip lead to a load transfer through the threads of the cup. The integration of the stem relies on cortical interlocking. Proximal linear radiolucencies do not impair function. The signs of osseointegration around the cup can be fully demonstrated only by a specially tilted X-ray beam at a right angle to the screw direction of the cup.
Dohle
J
J
Orthopädische Klinik Volmarstein, Universität Witten/Herdecke, Wetter, Germany. dohle@gmx.net
Becker
W
W
Braun
M
M
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging / Q000601:surgery; D001863:Bone Screws; D005260:Female; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging / Q000601:surgery; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D016348:Osseointegration / Q000502:physiology*; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000601:surgery; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011474:Prosthesis Design; D011859:Radiography; D012189:Retrospective Studies; D016474:Weight-Bearing / Q000502:physiology