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HI LUBRICER

Cementless Threaded Cup System

HI

Algemeen

HI cementless threaded cup system – A successful concept since 1988.1,3,5

Since the first implantation in May 1988, the HI cup has been implanted with unchanged external geometry and material. The typical features of the HI cup are its single-start flat thread and the bone-sparing parabolic shape, which leads to excellent screwing properties and high primary stability.1,2,5-7 Surgeons have an option of  either ceramic-, REXPOL™- or polyethylene-inserts with direct anchoring in the titanium shell.

The flat thread of the HI Cup

The thread of the HI cup is flat, which means that the teeth of the thread remain the same for their whole depth, the surfaces of the teeth run parallel to each other. This makes the cup genuinely self-tapping. With the flat thread, there is no broadening when screwing in, but only a deepening of the threads, which does not lead to jamming.4-6 The flat thread sinks into the bone and removes the slivers of bone from the bed (low flank forces).4 Furthermore, this special thread shape enables self-centering and closely fitting implantation of the cup even in an extensively sclerotic acetabular socket, without any jamming of the thread.1,5,7 The last turn of the thread is continuous and thus preventing soft tissues from being squeezed when screwing the cup into place.

Internal geometry

The HI cup has a circular opening on the pole so that the cup can be positioned with precision in relation to the depth of implanting. If the distance between the implant and the inner surface of the bony socket is too great, e.g. in the case of protruding acetabular bone, this gap can be filled with cancellous bone. Once the cup is seated in its final position, the opening is closed with a titanium cover.

The HI cup has four recesses on the equator, which are used to accommodate the introducer and for preventing rotation of the PE insert.

Inserts
The standard inserts sit flush with the rim of the shell. Only two insert sizes are needed for all HI cups, which is a great advantage in terms of storage.

Bearing
The HI cup system includes inserts for ceramic-ceramic bearing in BIOLOX® delta as well as standard and dysplasia inserts in REXPOL (XL-PE) and conventional polyethylene. In addition, PE retention inserts are available, with which increased luxation stability can be achieved.7-9 All inserts can be anchored directly into the HI cup.

Material and Surface
The HI cup is made of pure titanium according to ISO 5832-2.  The corundum-blasted surface has a surface roughness of 4 – 8 μm.

 

BIOLOX® delta is a registered trademarks from CeramTec GmbH, Germany, CE0123.

 

References:

  1. Metzner C, Strassl R, Neumann DRP, Hitzl W, Ramsauer T, Dorn U. Long-Term Results of the Cementless Hofer-lmhof Threaded Titanium Cup.  ZOrthop Unfall 2009; 147: 166-174
  2. Effenberger H, Imhof M, Witzel U, Kaelin P, Reiger W. Modifications of Shape, Material and Modularity of Threaded Cups. Biomed Technik 2002; 47 : 169-175
  3. Effenberger H, Ramsauer T, Böhm G, Hilzensauer G, Dorn U, Lintner F. Successful hip arthroplasty using cementless implants in rheumatoid titanium arthritis. Arch Orthop trauma Surg. 2002; 122 (2) :80–87
  4. Effenberger H, Imhopf M, Witzel U. Gewindedesign von Schraubpfannen. Z Orthop  2001; 139:428-434
  5. Effenberger H, Weber M, Dorn U, Hofer H. Röntgenkriterien und radiologische Ergebnisse der Hofer-Imhof (HI)-Schraubpfanne bei Erstimplantation. Z. Orthop 1997; 135: 434– 443
  6. Effenberger E, Imhof M, Witzel U. Criteria for Success with Threaded Cups. Acta Chirurgiae ORthopaedicae 2003:  285-291
  7. Bader R, Steinhauser E, Scholz R, Simnacher M, Mittelmeier W. Experimentelle Analyse von neutralen, asymmetrischen und Schnapp-Pfannen für die Hüftendoprothetik; Zeitschrift für Orthopädie 2004; 142:1–9
  8. Padgett DE, Warashina H. The Unstable Total Hip Replacement. Clin Orthop 2004; 420:72-79
  9. Yun AG, Padgett D, Pellicci P, Dorr LD. Constrained Acetabular Liners, Case Report. The Journal of Arthroplasty 2005; 20 (4): 536-541

 

Clinical evidence

Long-Term Results of the Cementless Hofer-lmhof Threaded Titanium Cup
Autoren InstituteC. Metzner1, R. Strassl1, D. R. P. Neumann1, W. Hitzl2, T. Ramsauer1, U. Dorn1ZOrthop Unfall 2009; 147: 166-174