Press fit fixation of cementless cups: how much stability do we need indeed?

Introduction: Using screws for a better primary and secondary fixation has been discussed in the literature of the recent years, although the principle of press fit has been explained as the principle of a push-button. The authors wanted to compare their own results in patients using X-rays from the postoperative course to decide if it is really safer to use screws or not. Materials and methods: Two hundred and twenty one consecutive, not selected patients were treated with total hip arthroplasty using a cementless cup type Duraloc. They were followed up over a time of 5 years for radiological changes of the bony acetabulum around the cup (“acetabular zones” according to De Lee and Charnley). One hundred and ten cups were additionally fixed with one to three screws at the upper part in region C1, 101 cups were implanted without the use of screws. Results: Periprosthetic changes visible on the radiographs (immediate postoperative gaps, subsequent sclerosis and radiolucent lines) were assessed according to the time of their appearance. A gap in zone C2 was seen more often immediately after operation within the group without screws (17.8% vs. 7.3%) and disappeared within the following 25 months. Within the group with screws significantly more often a gap was found in zone C1 and C3 compared to the group without screws (7.3% vs. 1.9%). In the group with screws a sclerosis of the bone in zone C1 developed in 32.7% mostly within the first 5 months. It was followed by a radiolucent line in zone C3 in 28.2% mainly within 5–25 months postoperatively and in zone C1 in 20.9% within 16 months. Significantly less seldom were these phenomena seen at the cups without screw fixation. There was no correlation between lateral or medial positioning and deviations from the ideal inclination to the bony changes around the cups. No signs of loosening occurred in either group. Conclusion: Less radiological changes around the cup if no screws were used and no disadvantages within this group led to the conclusion that an additional screw fixation in principle is not necessary in press-fit cups.

[1]  W. Harris,et al.  The Harris-Galante porous acetabular component press-fit without screw fixation. Five-year radiographic analysis of primary cases. , 1994, The Journal of arthroplasty.

[2]  D. Fisher 5-year review of second-generation acetabular cup with dome screws. , 1999, The Journal of arthroplasty.

[3]  W. Fischer Acetabular anatomy and the transacetabular fixation of screws in total hip arthroplasty. , 1991, The Journal of bone and joint surgery. American volume.

[4]  F. Kummer,et al.  Stability of press-fit acetabular cups. , 1992, The Journal of arthroplasty.

[5]  W. Harris,et al.  The Harris-Galante porous-coated acetabular component with screw fixation. An average ten-year follow-up study. , 1999, The Journal of bone and joint surgery. American volume.

[6]  K. Widmer,et al.  [Cementless socket fixation based on the "press-fit" concept in total hip joint arthroplasty]. , 2002, Acta chirurgiae orthopaedicae et traumatologiae Cechoslovaca.

[7]  R. Barrack,et al.  Tissue growth into porous-coated acetabular components in 42 patients. Effects of adjunct fixation. , 1992, Clinical orthopaedics and related research.

[8]  J. Charnley,et al.  Radiological demarcation of cemented sockets in total hip replacement. , 1976, Clinical orthopaedics and related research.

[9]  G. Salis-Soglio,et al.  Arthrodesis of the metatarsophalangeal joint of the great toe , 1979, Archives of orthopaedic and traumatic surgery.

[10]  L. Dorr,et al.  Comparison of Preoperative Radiographs and Intraoperative Findings of Fixation of Hemispheric Porous-Coated Sockets , 2001, The Journal of bone and joint surgery. American volume.

[11]  L. Dorr,et al.  Hemispheric Titanium Porous Coated Acetabular Component Without Screw Fixation , 1998, Clinical orthopaedics and related research.

[12]  J. Hollis,et al.  Initial Stability of Porous Coated Acetabular Implants: The Effect of Screw Placement, Screw Tightness, Defect Type, and Oversize Implants , 1994, Clinical orthopaedics and related research.

[13]  T. Hearn,et al.  Micromotion of cementless hemispherical acetabular components. Does press-fit need adjunctive screw fixation? , 1995, The Journal of bone and joint surgery. British volume.

[14]  A G Patwardhan,et al.  Acetabular micromotion as a measure of initial implant stability in primary hip arthroplasty. An in vitro comparison of different methods of initial acetabular component fixation. , 1992, The Journal of arthroplasty.

[15]  R. Barrack,et al.  Quantitative analysis of tissue growth into human porous total hip components. , 1988, The Journal of arthroplasty.

[16]  H Bereiter,et al.  Cementless press-fit cup. Principles, experimental data, and three-year follow-up study. , 1989, Clinical orthopaedics and related research.

[17]  F. Kerschbaumer,et al.  The Transgluteal Approach to the Hip Joint , 1979, Archives of orthopaedic and traumatic surgery.

[18]  D. Hungerford,et al.  The initial stability of uncemented acetabular components. , 1992, The Journal of bone and joint surgery. British volume.

[19]  W. Maloney,et al.  A quantitative in vitro assessment of fit and screw fixation on the stability of a cementless hemispherical acetabular component. , 1994, The Journal of arthroplasty.

[20]  E. Morscher,et al.  Development and first experience with an uncemented press-fit cup. , 1988, Clinical orthopaedics and related research.

[21]  E. Morscher,et al.  Current status of acetabular fixation in primary total hip arthroplasty. , 1992, Clinical orthopaedics and related research.

[22]  J. Galante,et al.  Histology of porous-coated acetabular components. 25 cementless cups retrieved after arthroplasty. , 1993, Acta orthopaedica Scandinavica.

[23]  M. Müller,et al.  The value of preoperative planning for total hip arthroplasty , 1998 .

[24]  J B Stiehl,et al.  Mechanical stability of porous-coated acetabular components in total hip arthroplasty. , 1991, The Journal of arthroplasty.

[25]  T. Brown,et al.  Areas of contact and extent of gaps with implantation of oversized acetabular components in total hip arthroplasty. , 1994, Clinical orthopaedics and related research.

[26]  W H Harris,et al.  The Harris-Galante porous-coated acetabular component with screw fixation. Radiographic analysis of eighty-three primary hip replacements at a minimum of five years. , 1992, The Journal of bone and joint surgery. American volume.

[27]  M. Ritter,et al.  Structures at risk from medially placed acetabular screws. , 1990, The Journal of bone and joint surgery. American volume.

[28]  L. Dorr,et al.  Cementless Hemispheric Porous-Coated Sockets Implanted with Press-Fit Technique without Screws: Average Ten-Year Follow-up , 2002, The Journal of bone and joint surgery. American volume.

[29]  M. Ries,et al.  Acetabular Strains Produced by Oversized Press Fit Cups , 1997, Clinical orthopaedics and related research.