Distally locked stems in revision hip arthroplasties: surgical technique and indications

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In case of severe femoral bone loss, cementless revision hip arthroplasties require a stable initial distal fixation that does not compromise a subsequent bone reconstruction. The locking mechanism provides initially reliable fixation, especially if bone loss has spread to the distal femoral isthmus or when an extended trochanteric osteotomy (femorotomy) is indicated. Locking stems can be used in all types of femoral revision, but this type of implant can be especially useful in case of diaphysial damage (beyond the isthmus) which makes fixation of a long cemented or non-cemented stem uncertain; in case of septic revisions which need a careful femoral cleaning; in case of peri-prosthetic fractures or if surgical complications (false route, fracture, perforations) occur that impair fixation of a cemented stem or one that is not of standard length. All approaches may be used, but the need for access to the femur dictates choice of the antero-lateral and especially the postero-lateral route. The choice of diameter is guided by “press-fit” beyond the femorotomy, thus minimizing the stresses that will consequently be exerted on the locking system. The size will be chosen also to optimize the contact between residual bone and prosthetic surface treatment in the metaphysial proximal and diaphysial regions. The stem must be locked depending a few technical requirements. The position of the stem will be chosen regarding limb length (height) and joint stability (anteversion). The quality of femorotomy closure is evaluated by achieving broad contact between the flap and the proximal part of the stem. When the medial part of the femur relative to the flap remains distant from the stem, a “counter-femorotomy” of medial cortical bone made at a different level should be performed to optimize contact. These implants simplify femoral revisions by facilitating femorotomy in complex situations. This method offers constant bone reconstruction without significant bone grafting and durable fixation if locking mechanism is added to an adjusted implant in contact with native bone, limiting short-and long-term stresses on it.