[Cement-within-cement femoral stem reimplantation technique]

The reimplantation of a cemented femoral component at revision is always a challenge for the orthopaedic surgeon, particularly when the cement mantle is intact. The aim of this study was to provide evidence that the recementing of a femoral stem into the original cement mantle can be included in routine surgical procedures.

A group of 104 patients with femoral stem revision, followed-up for an average of 50.2 months, were retrospectively reviewed. The outcome evaluation was focused, in the first place, on survivorship of the femoral component, acetabular migration, and dislocation and infection after revision arthroplasty. Hip function evaluation was based on the Harris hip scores before surgery and at the latest follow-up. On radiographs Gruen zones were assessed pre-operatively and at the latest follow-up. The results were statistically evaluated using the Kaplan-Meier survival analysis (Statistica 8.0).

Of the 104 patients, only three (2.9 %) had stem re-revision due to its loosening. Further 16 patients underwent revision for other post-operative complications. The success rate of reimplantation in our group including all post-operative complications was 81.7 %. The average Harris scores were 56 before surgery and 87 at the latest follow-up. Radiolucent lines in Gruen zones were on average 0.45 mm in width before revision and 0.15 mm at the latest follow-up. Fourteen patients had second revision within 20 months of the first and only five were revised after a long period.

The cement-within-cement exchange of a femoral component is a relatively frequent orthopaedic procedure. Despite this frequency, however, there have not been enough literature reports based on large patient groups to give support to its routine use. The aim of this study was to demonstrate on a large patient group that recementing a femoral stem into the original intact cement mantle can be considered an established operative technique. Our results suggest that the list of indications for this technique, as described by Lieberman and Nelson, can be extended by the following: broken stem with an intact distal cement mantle, replacement of a monoblock femoral component due to severe head damage, loosening of the femoral component without impairment of the distal cement mantle, conversion of a cervico-capital to a total hip replacement and the need of removing all bone cement. No risk is associated with reimplantation of the original component if there is no need for a different implant to correct angle or length stability. A new implant is always used when any part of the femoral component has been damaged mechanically. If only the proximal stem requires recementing, the use of the original component is preferred because of absolute cement/stem cohesion. The number of our patients in which the technique failed was generally in agreement with the results of other authors.

Utilisation of the original cement mantle of a femoral component is one of the options at revision arthroplasty. It requires rational considerations based on the type of surgery, state of the cement mantle, and type of material used for the femoral stem. The method is indicated preferably in the hips with an intact cement mantle treated for loosening of the acetabular component, recurrent dislocation or unequal leg-length in monoblock femoral components. In such situations the removal of well-fixed cement would also involve a considerable loss of bone tissue. The follow-up outcomes showed that the involvement of the cement-within-cement technique in routinely used surgical procedures is fully justified.