[Anatomic reconstruction of hip joint biomechanics: conventional vs. short-stem prosthesis].
BACKGROUND
Currently, short cementless femoral stems are alternative implants to treat osteoarthritis in young patients with sufficient bone quality in order to get a more proximal load transfer. The purpose of the present study was to biomechanically compare joint reconstructions resulting from implantations of a short-stemmed and a conventional hip replacement.


METHODS
100 patients (50 short-stemmed and 50 conventional) were retrospectively examined. For evaluation of biomechanical parameters standardised pre- and postoperative X-rays (pelvic AP views) were used and digitally analysed.


RESULTS
The horizontal femoral off-set increased within both groups (short: 2.0 mm and conventional: 3.3 mm), with a significant increase in the conventional group. The hip centre of rotation was significantly medialised after both procedures (short: 6.0 mm and conventional: 4.2 mm). Limb length was shorter preoperatively at the arthroplasty side, but increased thereafter (short: 2.1 mm and conventional: 2.6 mm). Compared to the native contralateral side the limb length was almost equal after THA (short: 0.7 mm and conventional: 0.8 mm).


CONCLUSIONS
Our study shows that an almost anatomic reconstruction of hip joint biomechanics is possible with a short-stemmed prosthesis compared to a conventional stem, regarding limb length, centre of rotation and offset.
Klinik und Poliklinik für Orthopädie und Unfallchirurgie, Universität zu Köln.
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C
Ries
Arcus Kliniken Pforzheim.
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Schopf
Arcus Kliniken Pforzheim.
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F
Dietrich
Arcus Kliniken Pforzheim.
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S
Franke
Labor für Biomechanik, Klinik und Poliklinik für Orthopädie und Orthopädische Chirurgie, Justus-Liebig-Universität Gießen.
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Jakubowitz
Arcus Kliniken Pforzheim.
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Sobau
Zentrum für Orthopädie, Unfallchirurgie und Sportmedizin, Orthopädie Kurpfalz, Speyer-Mannheim-Heidelberg.
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C
Heisel
D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods; D019544:Equipment Failure Analysis; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular; D016896:Treatment Outcome