Abstract
Introduction
Extensive bone loss and poor residual bone quality can make implant fixation difficult to achieve in revision of failed megaprostheses. While newer porous components are available to address various periarticular cavitary and segmental defects, diaphyseal fixation remains challenging without resorting to cemented techniques, or cementless fully-coated stems that achieve fixation over long segments of bone. In cases of previous infection, it may be advantageous to avoid the use of such devices as they can be difficult to remove and may result in even greater bone loss if the infection were to persist. Compressive osseointegration technology has been become a valuable device in the management of these challenging situations.
Objectives
We aimed to evaluate the short-term results of compressive osseointegration when used for reconstruction of massive diaphyseal and segmental bone defects. We believe that compressive osseointegration provides predictable, strong endoprosthesis fixation in the short-term and that osseointegration can be evaluated radiogrphically.
Methods
We retrospectively reviewed a total of 32 implants (spindles) in 28 patients with failed prior megaprosthetic reconstructions. Procedures were performed at two institutions by six surgeons. Data recorded included patient demographics, indication for surgery, diaphyseal segment and joint reconstructed, and any complications.
Results
Average patient age and body mass index at time of surgery were 48 years (range 14–68) and 28.1 m2 (range 17–58), respectively. Indications included aseptic loosening (18), loosening and infection (11), and allograft-prosthetic composite nonunion (3). The reconstructions consisted of distal femoral replacement (16), proximal femoral replacement (10), distal humeral replacement (4) and proximal ulnar replacement (2). There were five spindle failures in 4 patients. Three were converted to a Compress device, two were successful one converted to a cemented stem and another patient was also converted to a cemented stem. Other complications that required repeat surgery included hinge failure (2), arthrofibrosis (1), segment taper adapter fracture (2), persistent chronic deep wound infection (1)and superficial wound infection (1). Fixation at the bone-implant interface remained intact in each of these cases. There was 1 deep infection in this series in spite of a large number of index infected megaprostheses. Twenty-six of twenty-eight patients (92.8%) achieved stable osteointegration and we had an overall spindle osteointegration failure rate of 15.6% (5 of 32) at a mean follow-up length of 16.7 months (range 0.5–57.4). The cortex/spindle ratio of these increased from 0.33 (SD 0.9) immediately postoperatively to 0.53 (SD 0.15) at final follow-up (p < 0.001). At most recent follow-up, these patients reported satisfaction and painless function of the operative limb.
Conclusion
Use of compressive osseointegration for revision of failed massive segmental bone defects (See Fig 1 and 2) provides reliable short term fixation, and may prove to be bone conserving in cases that require future re-revision. The cortex/spindle ratio reliably increases over time as fixation is achieved. It has become our device of choice for failed limb salvage reconstructions.
