None of the authors have any commercial interest in any of the products described in this technical note.
Background
Revision hip surgery can be a complex undertaking. A recent option for reconstruction of the acetabulum with major bone loss is the use of porous metal augments around a hemispherical shell such as the Trabecular Metal™ modular acetabular system (Zimmer, Warsaw, IN, US). These implants have demonstrated excellent bone ingrowth and incorporation into pelvic bone stock.1,2 Nevertheless, this presents a technical problem should these implants need to be revised, for example in the presence of deep seated prosthetic infection. The Explant® acetabular cup removal system (Zimmer) was designed to remove uncemented hemispherical acetabular shells. We describe the use of the Explant® for the removal of porous metal periacetabular augments.
Technique
The shell can be removed in the conventional manner using the Explant®. The same device can then be used to remove the periacetabular augments. Initially, the small blade is used on the Explant®, followed by the larger blade. However, the Explant® is impacted circumferentially about the augments with a mallet rather than in the traditional rotational manner (Fig 1). This overcomes the problem of the augments not possessing a corresponding internal diameter. The Trabecular Metal™ augments can then be lifted easily out of the acetabulum with minimal bone loss (Figs 2 and 3).
Figure 1.
Explant® removing Trabecular Metal™
Figure 2.
Acetabular augment removed with minimal bone loss
Figure 3.
Minimal acetabular bone loss
Discussion
This is a proposed further use for the Explant® system in what is becoming an increasingly encountered prosthesis for the revision surgeon.
References
- 1.Bobyn JD, Stackpool GJ, Hacking SA et al. Characteristics of bone ingrowth and interface mechanics of a new porous tantalum biomaterial. J Bone Joint Surg Br 1999; 81: 907–914. [DOI] [PubMed] [Google Scholar]
- 2.Lewallen D, Meneghini M, Poggie R et al. Revision hip arthroplasty with porous tantalum augments and acetabular shells. Presented at: Annual Meeting of the American Academy of Orthopaedic Surgeons; March 2006; Chicago. [Google Scholar]