Threaded titanium implants with an osseointegrated surface in hip arthroplasties similar to the best dental implants in the jawbone !
In the past implants of chromium, cobalt, Vitale or ceramic have been tested with “Press Fit” or threaded fastening technique in the jawbone in order to replace worn teeth.
From 1970 to date only screw dental titanium implants whith an osseointegrated surface have established because they showed the best permanent stable fixation and have a larger contact surface with the bone compared to other materials of the same diameter.
So in the hip joint also new generation threaded acetabular titanium implants Zweymuller type with thin fins (lamelae) and roughened and osseointegradable surface showed excellent permanent results as in our long series of patients at the acetabulum site which is similar in formation to that of the remaining area of the jawbone after the removal of a damaged tooth.
In hip arthroplasties in contrast with the successful threaded teeth implants they have been slow to be established internationally because many orthopedic hip surgeons thought that they are not so good because they had similar shape with the unsuccessful old Mittelmeiyer type, Link, PCA or other anelastic and with smooth surface screwed hip cups used mainly in the 1980s which were accompanied by large percentages of mechanical loosening. These old cups had showed only primary mechanical stability but not permanent biological fixation and no periprothetic new bone formation.
The difference is that the new generation titanium threaded dental or Zweymuller and similar type implants are no so rigid and they have roughened titanium surface and thin fins (lamaele) with excellent osseontigration possibility and permanent biological fixation.
Thanks to the famous professor of Vienna Zweymuller many orthopedic surgeons including myself became aware of the considerable capabilities of these new threaded titanium acetabular implants. The Zweymuller cup with titanium roughened and osseointegrated surface has sharp-cutting thread blades able for improve the penetration of the thread teeth even into an subchondral sclerotic zone.
So, after several years of scientific erroneous assessment and in continuance to the excellent Zweymuller cup results, many other similar threaded titanium cups with osseointegrated surface are now introduced in the market ( Smith & Nephew, Zimmer, Implant Cast, Lima, Permedica, Aesculap and many others ) and make unnecessary the problematic – mainly in the revision hip arthroplasty surgery – use of acrylic cement or screws.
The results in hip arthroplasties are excellent and perfectly comparable to those of highly successful dental screw implants in both simple cases of hip osteoarthritis and in cases of osteoarthritis secondary to congenital dysplasia, low congenital hip dislocation or other deseases.
Especially in cases in which the threaded titanium acetabular implant is combined with rectagular antirotational stem with osseontegrated also surface the result is almost perfect.
There are indications that the coveraged with new periprothetic bone threaded titanium implant surfaces without necrotic area between implant and bone – as in cases in which acrylic cement is used – reduces the risk of infections. Around mandibular threaded titanium implants although the mouth is not a sterile area rarely are caused infections.
In our Clinic we place these implants using the new so-called ALMIS (Antero-Lateral Minimally Invasive Surgery) tecnique. This modified our technique has established in the Master Techniques in Orthopaedic Surgery as “Mayo Limited – Minimal Anterior” – USA.
The usually very laborious and complicated revision surgery to remove broken screws from the iliac bone or acrylic cement in cases of a hip arthroplasty loosening is avoided.
The absence of screws or acrylic cement in threaded titanium acetabular prostheses makes easy the review process in very rare cases of loosening and leaves enough healthy periprosthetic bone intact or not infected to place a new one threaded titanium implant.
Threaded titanium implants with osseointegrated surface in the jawbone and hip acetabulum seem to be the most ideal and permanent solution to these difficult and too loaded damaged bone areas ! This is the future..
Zweymuller Hip Arthroplasty
Surgical Experience of 1000 Zweymuller Cases
The “High Hip Center” Technique in Deficient Acetabulum. N. Christodoulou
High Hip Center Technique Using a Biconical Threaded Zweymüller® Cup in Osteoarthritis Secondary to Congenital Hip Disease, N. Christodoulou et al. Clin Orthop Relat Res. 2010 Jul; 468(7): 1912–1919
Screwed cups a valid alternative.wmv