Conventional Hip Replacement and Hip Resurfacing

1 The hip resurfacing is considered as a new generation of Hip Replacement.

1. Conventional Hip Replacement:

1.a. The Conventional Hip Replacement of first generation is composed by a cemented femoral stem.

A total hip replacement (THP) is composed by three parts: a plastic cup with metalback that replaces the hip socket (acetabulum); a metal ball to replace the femoral head; and a metal femoral stem that attached to the bone shaft.
The total hip prosthesis are in this case fixed with biological cement.
Several years after their implantation, sometimes they will wear out and need to be replaced again; this second operation is called revision and it is considered a long operation because at first we need to remove the old cement, taking care on the bone because it is very weak and after we need to prepare correctly the place which will receive the new prosthesis (in some cases, we need to do bone graft) and at the end we implant the new prosthesis.

2.a. The Conventional Hip Replacement of second generation is composed by a cementless femoral stem or with coating.

Theses prosthesis are called cementless because we don't need to use a bilogical cement to fixe them.
Their surface are made with a special coating looking like bone composition (hydroxyapathite) and with a characteristic similar than the bone morphology: the porous coating.

Exemple of cementless THP

Some clinical cases:

1st Case: hip arthritis consequent of a congenital desease ( epiphysiolysis):

Left side: before the implantation of the THP
Right side: after the implantation of the THP

2d Case: Hip arthritis consequent of femoral head necrosis:

3d Case: hip arthritis consequent of an old fracture:

The right hip has two problems : a congenital dislocation of the femoral head and a consequence of an old fracture of the femur.

In this complex case, at first we build a new acetabulum for receiving a cup and after we need to do osteotomy for reaxing the femur and to insert a long femoral stem.

2. Hip Resurfacing:

The Hip Resurfacing are considered the third generation of the Hip Replacement.

They have been implanted since the beginning of the 1990 years with perfectly established results (series of Mac Minn in England, of Amstutz in the USA, De Smet in Belgium...)

They bring many advantages:

• Femoral head and femoral canal are preserved and no associated femoral bone loss with future revision. Moreover, the risk of microfracture of femur with uncemented stem implantation is eliminated.
• Larger size of implant "ball" reduces the risk of dislocation in a significant way.
• Stress is transferred in a natural way along the femoral canal and through the head and neck of the femur. With the standard hip prosthesis, some patients experience thigh pain as the bone has to respond and reform to less natural stress loading.
• Use of metal rather than plastic reduces osteolysis and associated early loosening risk.
• Use of metal has low wear rate with expected long implant lifetime.
• they replace only the surface of the damaged cartilage, do not comprise a stem in the femur ;
• thus, they constitute a relatively conservative treatment;
• combines with this concept of resurfacing (implants with reduced size), the notion initially surgical less complicated (with the antero-lateral approach especially) with conservation of the bone and muscles ;
• immediate total stability of the press-fit of the prosthesis and stability in time;
• simplified operational steps and definitely less pain; possibility of walking with complete support very quickly after the intervention...

Bibliographic Références:

Hip International 2003; 13: 41 - 53
Development of Metal/Metal Hip Resurfacing
D.J.W. McMinn (Royal Orthopaedic Hospital, Birmingham – UK)

Hip International 2002; 12: 158 - 162
Early results of primary Birmingham hip resurfacing using a hybrid metal-on-metal couple
K.A. De Smet*, C. Pattyn1, R. Verdonck*
*Ghent University Hospital, Ghent – Belgium

Metal-on-Metal hybrid surface arthroplasty: two to six year follow up.
by Harlan C. Amstutz*, M.D.; Paul E. Beaule, M.D., FRCSC; Frederick J. Dorey Ph.D.; Michel J. Le Duff, M.A.; Pat A. Campbell, Ph.D.; Thomas A. Gruen, MS
*Joint Replacement Institute, Los Angeles-USA

Quand et comment opérer les coxarthroses du sujet jeune ?
(When and how to operate young patients with hip arthritis ?)
R. Mosseri – Paris
www.rhumatologie-bichat.com (« Annales Congrès du sport 2004 »)