Distally locked femoral stems offer patient satisfaction

By Claus Varnum, MD, Vejle Hospital, Denmark

During the Distally Interlock Femoral Revision Stem symposium, Patrice Mertl, MD; Phillippe Rosset, MD; and Rémi Phillipot, MD, presented a retrospective inclusion study of 725 patients, of which 415 underwent revision hip arthroplasty.

Bone damage was evaluated according to the SOFCOT classification and was in stages 0-IV. During surgery, in which the patient is lying in a lateral position, the transfemoral approach is utilized and a femoral flap is created and the implant and cement are removed. Before reconstruction of the femur, a metal wire is circulated around the femoral bone just distal to the femoral flap, which was closed with three to five wires, and the stem is locked distally with one to eight screws, most commonly two or three.

They reported that the overall clinical results revealed that 79% of patients had no pain; 16.5% had stress pain; and 4.5% had incapacitating pain. They also found that 87% said they were satisfied or very satisfied, and 3.6% said they were not satisfied with the surgery.

Complications

They reported some complications including, 106 (14.6%) intra-operative fractures and a 1.4% rate of breakage of screws and stems. Stem breakage occurred at the level of the first screw, they said, and an important risk factor is a stem diameter less than 12 mm.

Screw removal was performed in 63 cases, but no clinical improvement was seen afterwards leading the presenters to not recommend removal of broken screws. Both aseptic and septic loosening of the stem were described. In aseptic loosening, if the metaphyseal filling index (MFI) —- the relation between the stem diameter and the femoral canal diameter – is less than 75%, 83% of stems were, if it was greater than 75%, 94% of stems were stable.

They agreed that they had a generally good experience in using a distally locked revision stem in treating peri-prosthetic fractures.

Satisfaction ratings

The speakers summarized, that 87% of patients were satisfied or very satisfied, and radiologically 80% of stems were stable. They reminded the audience that the procedure is difficult to perform, and only experienced surgeons should use this technique.

In that cohort, there was a 15% rate of intra-operative complications and 17% underwent reoperations. According to the speakers, the absolute indications are severe loosening, SOFCOT stage III and IV, and periprosthetic fractures, especially in the Vancouver type B fractures. Fracture union was seen in 95% of cases, and stem fixation was obtained in 86%, they said.

The presenters noted that one relative indication for complications was septic loosening. In the presented study 7% of patients with septic loosening had re-sepsis – certainly because of good cleaning possibilities because of the femoral flap.

At the end of the discussion the speakers asked the audience, if any used distally interlocked femoral revision stems; only a few responded that they had.