FORUM DE L’INSTITUT MARCEL KERBOULL
Traitement des descellements cotyloïdiens aseptiques
avec perte de substance osseuse majeure.
Paris, Vendredi 31 Janvier, 2003
WHAT TO PUT IN?
HA COATED IMPLANTS .
J.P. VIDALAIN . ARTRO Group .
Clinique du Lac . 22, rue André Theuriet . 74000 . ANNECY . France .
1. Thank you for this opportunity to present our strategy regarding severe acetabular defects,
2. using HA coated components . Reconstruction poses a considerable challenge in the
presence of significant bone loss, and
3. It is clear that in such situations, we need not only a rational strategy, but also specific
implants adapted to the seriousness of the situation after the extraction of the failed
prosthesis.
4. If the choice of cemented versus cementless THA is still a topic of controversy for mild
and moderate bone stock loss, cementless revision surgery has increasingly gained
acceptance over the last decade, in case of severe deficiencies.
5. On the acetabular side, is cementless revision reliable ? We know that the excellent
clinical results of HA coated implants in primary surgery are entirely related to good
osteo-conductive properties resulting in well-fixed implants in the presence of wellvascularized native bone .
6. Therefore application in revision surgery is more challenging either from a mechanical or
from a biological point of view .
7. Repair and augmentation of bone defects is not only usefull, but unfortunately, often
mandatory on the acetabular side : in many cases, morcellized grafts must be used in
combination with structural blocks .
8. What to put in, after removing a failed acetabular component ? According to the different
patterns of bone loss, we use either hemispherical cups or a modular device.
9. In Paprosky’s types 1 and 2 defects, the acetabular rim is preserved and the anterior and
posterior columns permit the use of a standard cup . In some extensive erosions, the use of
an oversized implant is preferable .
10. Two kinds of jumbo cups are available, the threaded component Tropic or the impacted
shell Lagoon ; additional screws can improve the primary stability .
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11. This type of component is used in the majority of our revision cases : because of a close
contact with the living bone, because of the small amount of graft material, the
management of the post-operative period is similar to that of a primary surgery .
Functional results are excellent,
12. And radiological analysis have confirmed, the stability and the quick osteintegration of the
cup . The topography of the new hip center has been evaluated .
13. If the center of rotation is not usualy in an anatomical position, the risk of lateralisation is
not so important as mentioned in the literature .
14. And if a high hip center is noticed in 57% of the cases, the difference is not really
significant .
15. Globaly, this new hip mechanics have strictly no consequence on the final functional
outcome.
16. Major deficiencies including types 3 and 4 defects, need a specific, modular device.
17. The OCTOPUS modulus offers an effective strategy for dealing with each of these
problems. The system comprises three modular components :
 An outer acetabular ring,
 A hemispherical acetabular shell,
 An inner polyethylene liner .
18. The acetabular ring is manufactured from pure titanium . The ring is located on the
acetabular rim by its inferior hook securely locked into the obturator foramen . The two
superior legs, can be fixed in sound iliac bone outside the damaged area .
19. The shell is mounted on the acetabular ring by four connecting screws . Multiple holes
allow the surgeon to secure and to compress bone grafts into host bone . The outer shell is
spray-coated with HA .
20. The PE liner fits tightly within the shell . A standard hooded liner or a reorientation liner
can be selected .
21. A complete set of templates permits an accurate pre-operative planning .
22. VIDEO CLIP .
 Any of the standard approaches may be use for OCTOPUS implantation . However, the
wound should be enlarged to fully expose all the acetabular rim . The failed acetabular
component, all the cement debris are removed . The acetabular bed must be cleared of any
fibrous tissue, cysts and granulomas . The diameter of the acetabular cavity is evaluated
and

The trial ring is placed on the acetabulum and oriented in 45° of abduction , and 15° of
anteversion . Once in position, this will provide a clear indication of the bone defects to
be filled.
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
The walls, the roof, the floor of the acetabulum are repaired using solid cortico-cancellous
grafts temporary retained by several pins . The trial ring is positioned once again and the
superior legs are adapted to the patient’s anatomy .

The legs of the definitive frame are adjusted according to the trial ring used as a template .

The definitive ring is correctly positioned over the grafted acetabulum, the inferior hook is
fully inserted into the obturator foramen, and the fixation of the superior legs achieve to
secure anchoring in healthy bone stock .

Any remaining defects are repaired by compacted morcellized cancellous bone to produce
an hemispherical cavity, and the shell is fixed to the ring .

Trial liners permit to select the appropriate liner and to adjust the correct orientation .
23. The post-operative X-ray control is in accordance with the programmation, and early
partial weight-bearing is normally permitted . Full weight-bearing being usally delayed
untill 45 days .
24. From 1990 to 1999, we have performed 73 OCTOPUS . The mean FU is 7 years . They were
all elderly patients with several associated pathologies .
25. The review of 48 files with more than 5-year FU, confirms all the benefit of the procedure.
The PMA score fully testifies to the functionnal handicap before the operation and to the gain
which can be expected after the reconstruction . The most significant improvement concerns
the pain parameter .
26. However, the percentage of complications confirms that this is relatively serious surgery .
27. X-ray assessment made it possible to check whether the anatomical, mechanical and
biological challenge had been met .
28. Anatomically, a physiological hip center has been re-established in 83% of the cases .
29. Mechanicaly, the different failures clearly show the stresses to which the reconstruction
modulus is subjected . However, many screw breakages are not correlated with any
loosening of the cup .
30. We can note that despite a significant amount of grafts, the rate of migration is relatively low.
31. Biologically, the integration of the grafted tissues is the major question . Radiological
assessment confirms definitly the integration in 32 cups, but on the over hand, we can talk of
8 failures with extensive lucencies, graft lysis or mobilisation of the modulus .
32. Nethertheless, in all our series, only 6 patients have been operated on for an Octopus
removal, and that gives a survival rate of 86 % at 8 years . At this stage, I would like to make
several comments because a successfull surgical technique, in particular with regard to the
right use of grafts, is absolutly imperative :
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33. A good anatomical reconstruction is essential in order to properly position the Octopus
modulus and to reduce the risks of dislocation in patients who have undergone several
operations .
34. On one hand, an inadequate reconstruction of the roof can lead to fix the ring too vertically.
One the over hand, filling up the acetabulum too much can eventually lead to an excessive
off-set of the modulus .
35. Primary mechanical stability is essential. The hook must be properly engaged in the
obturator foramen, and the legs fixed in reliable bone . The mechanical stabilisation must be
strong enough to withstand waiting for a necessarily slow biological integration .
36. Allografts must not be considered as a reliable support for a reconstruction modulus .
Actually, there is a race on between neo-osteogenesis and material fatigue .
37. Grafts incorporation poses the most serious problem . Is the secondary stabilization of a
bio-active implant in grafts a mere pipe-dream ?
38. Numerous experiments and creditable clinical results prove that allografts can become live
again and that the incorporation of a bio-active implant can become a reality .
39. But it is a total illusion to expect osteogenesis of scar tissue in an area deprived of any osteocompetent cells . We would therefore insist on a minimal supply of osteo-blastic precursors
(auto-graft or bone marrow).
40. Few cases now, to illustrate the possibilities and the limits of this device . First, a Mac KeeFarrar prosthesis implanted in 72 and revised 20 years later for this extensive loosening of
the cup . 3 femoral heads were needed to rebuilt the different columns and to fill in the
cavity.The result at 6-year FU, with this nice incorporation of the grafts and the perfect
stability of the modulus .
41. Another major destruction of the acetabulum associated to a fracture of the bottom of the
cavity . You can appreciate the quality of the anatomic reconstruction and the radiological
bone pattern after 3 years with an excellent clinical result .
42. A dramatic case with a pelvic discontinuity operated in 90 and the radiological result
showing a slight migration of the device without any failure of the material .
43. This grade 4 acetabular destruction has been operated in 96 . You can appreciate the great
amount of allografts needed to restore the natural anatomy . On the last X-ray control, you
can evaluate the compaction of the morcellized grafts, the global migration of the cup, but
the integrity of the device in accordance with the excellent functional result .
44. This loosening with severe bone loss has been operated in 91 , using a very significant bone
graft augmentation . 8 years later, the majority of the graft material is incorporated .The cup
migrated during the first year, and then, has found its definitive stability .
45. To conclude,
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46. Strict adherence to important principles is necessary to produce consistent and reliable
results :
 a pre-operative planning as well as rational strategy.
 a very large instrumentation kit.
 a large range of different implants to give an adaptable solution to any unpredictable
situation .
47. Data on revision surgery using HA coated implants, have been very encouraging and have
demonstrated that : once implants have acquired bony stability, the prospect for long term
prosthesis survival is very favorable, and restoration of a good periprosthetic bone
trophicity is a reality, even after significant bone grafting.
48. In addition, in all the cases where an octopus needed to be removed, we have been faced
to a very bleeding acetabular bed,
49. And we have been able to re-implant a standard hemispherical component.
50. However, there is no doubt that major deterioration takes us to the frontiers of reasonable
reconstruction and some extreme cases are beyond the possibilities of this type of device, and
perhaps even the possibilities of cementless reconstruction. The use of HA coated
components in such revisions, is far from being generally accepted, and it will be essential to
fully understand the biology of bio-active implants in a grafted site .
51. Thank you very much for listening .
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