Removal of well-fixed components in femoral revision arthroplasty with controlled segmentation of the proximal femur

Abstract

Background: The transfemoral and the extended trochanteric osteotomies are the most common osteotomies used in femoral revision, both when proximal or diaphyseal fixation of the new component has been decided. We present an alternative approach to the trochanteric osteotomies, most frequently used with distally fixated stems, to overcome their shortcomings of osteotomy migration and nonunion, but, most of all, the uncontrollable fragmentation of the femur.

Methods: The procedure includes a complete circular femoral osteotomy just below the stem tip to prevent distal fracture propagation and a subsequent preplanned segmentation of the proximal femur for better exposure and fast removal of the old prosthesis. The bone fragments are reattached with cerclage wires to the revision prosthesis, which is safely anchored distally. A modified posterolateral approach is used, as the preservation of the continuity of the abductors, the greater trochanter, and the vastus lateralis is a prerequisite.

Results: Between 2006 and 2012, 47 stems (33 women, 14 men, mean age 68 years, range 39-88 years) were revised using this technique. They were 12 (26%) stable and 35 (74%) loose prostheses and were all revised to tapered, fluted, grit-blasted stems. No fracture of the trochanters or the distal femur occurred intraoperatively. Mean follow-up was 28 months (range 6-70 months). No case of trochanteric migration or nonunion of the osteotomies was recorded. Restoration of the preexisting bone defects occurred in 83% of the patients. Three patients required repeat revision due to dislocation and one due to a postoperative periprosthetic fracture. None of the failures was attributed to the procedure itself.

Conclusions: This new osteotomy technique may seem aggressive at first, but, at least in our hands, has effectively increased the speed of the femoral revision, particularly for the most difficult well-fixed components, but not at the expense of safety.

Figure 1

The transverse distal osteotomy after prophylactic wiring is first performed.

Figure 2

Then controlled fractures of the proximal femur are generated with osteotomes. They may extend from the osteotomy site distally to, as far as needed, proximally to facilitate the stem removal, but not closer than 2 cm from the vastus ridge. The continuity of the abductors with the vastus lateralis and the GT with the lesser trochanter is thus retained. Normally, this extent of fragmentation of the femur is enough for the removal of the old prosthesis, as the area of remaining fixation is usually distal and proximally the prosthesis is loose. If, however, there are still areas of proximal bone ingrowth or when a stable implant is revised, the posterior aspect of the intertrochanteric region can be violated to facilitate the stem removal, as long as the trochanteric continuity is retained anteriorly. After stem removal, the canal preparation and the revision prosthesis insertion are performed under direct vision.

Figure 3

The bone fragments are reattached to the new prosthesis with two or three cerclage wires, depending on the extent of the fragmentation.

Figure 4

A case of a broken stem with a well-fixed proximal part. A 69-year-old female patient had an Autophor 900S stem implanted 15 years ago. This stem is entirely porous coated and has proximally two fenestrations for better anchoring. The arthroplasty became painful and an anteroposterior radiograph revealed a fatigue fracture of the middle of the stem. The distal part of the prosthesis seems firmly attached to the bone, whereas the stability of the proximal half is uncertain. During operation, this part could not be removed with standard techniques. Taking into account that distally the prosthesis is quadrilateral in cross section, it was decided to be revised with segmentation of the proximal femur.

Figure 5

Intraoperative photograph. Note the bone fragments (arrowheads), which are separated from the implant surface, but not from the attached soft tissues, the extracted distal part (small white arrow), the transverse osteotomy (large white arrow), and the intact trochanteric region with the abductors and the vastus muscle group attached (black arrow).

Figure 6

The immediate postoperative radiograph.

Figure 7

Six months later, the fractures have healed, the osteotomy has united, and remodeling has occurred.