CORR Insights®: Upshifting the Ipsilateral Proximal Femur May Provide Satisfactory Reconstruction of Periacetabular Pelvic Bone Defects After Tumor Resection

Where Are We Now?

Limb salvage with internal hemipelvectomy, pioneered by Enneking [2] and Steel [12], remains the go-to approach for reconstructing pelvic bone defects. However, reconstruction following resection of pelvic tumors is still a challenge for orthopaedic surgeons because of the high incidence of complications (infection, loosening, or collapse of the construct) associated with the various reconstructions.

In the current study, Lin and colleagues [6] reconstructed periacetabular pelvic bone defects after tumor resection utilizing a novel technique in which the entire proximal femur was stripped of its soft tissues, reflected proximally, secured to the remaining hemipelvis, and then an acetabular component was cemented into the now-devascularized bone. To replace the previously normal proximal femur, which was reflected superiorly, the authors opted for a proximal femoral replacement with a mesh reconstruction of the capsule.

This procedure provides a biological option to reconstruct the pelvic ring by keeping spinal/femoral articulation, and a strutting of the pelvis to retain the tension of the pelvic ring. Additionally, it offers a reconstruction that calls for no special implants and can be performed by most oncological surgeons.

Where Do We Need To Go?

As with most novel surgical approaches for otherwise-difficult reconstructions, we are left with gaps in our knowledge. The current study examined only 11 patients during a 10-year period, making it difficult to determine whether the complications and problems observed were a function of the learning curve or the technique itself. Also, we need to know whether these reconstructions will be durable, or over time will they sustain similar complications of pelvic allografts, since they probably do not fully vascularize?

I wonder whether surgeons are reluctant to try this technique because it involves sacrificing the abductors (which are important in hip reconstruction) in order to provide bone graft. Previous gait studies [4, 10] have demonstrated important functional deficits in patients who have lost their abductors in the course of tumor resections in the proximal femur; future studies will need to provide compelling reasons to make this trade.

Surgeons have primarily used proximal femoral implants for reconstruction of the proximal femur following resection of tumors. In addition, they also have been used in selected patients with failed hip arthroplasty implants associated with extensive bone loss in the proximal femur [11]. While implant survival is reportedly up to 90% at 10 years [3, 9, 13], “high stakes” procedures like these can have devastating consequences if implant removal is performed for any reason since resection arthroplasty in this setting results in an extensive bone and soft-tissue deficiency and a discontinuity [11] between the remaining femur and pelvis.

Numerous other alternatives can be utilized, such as “Figure 7” allografts, highly porous augments/cups/cages, and custom triflange acetabular components. These reconstruction procedures can be also utilized in patients following extensive pelvic resections [1]. Moreover, these procedures provide biological fixation against host bone, rather than placing a cemented cup against a devitalized portion of autogenous bone graft

How Do We Get There?

Three-dimensional (3-D) printed implants prepared ahead of time to match the anticipated defects may provide new options in these difficult situations. Accurate 3-D printed resection guides facilitate immediate reconstruction with exact implant match, and 3-D printed implants prepared ahead of time to match the anticipated defects may provide new options in these difficult situations. Accurate 3-D printed resection guides facilitate immediate reconstruction with exact implant match, and rapid prototyping technologies already have shown benefit in resection of extremity tumors compared to standard techniques [7]. Additionally, 3-D printing is currently established in aiding in the understanding and resection of pelvic tumors [8]. Initial reports have demonstrated excellent initial results applying this technology to reconstruction of pelvic tumor resections [5]. As 3-D printing progresses and experience grows with their application, there will be great potential for immediate anatomic reconstruction of challenging pelvic tumor defects. Additionally, in the case of infection or other construct failures, such procedures could allow for salvage via conversion to conventional resection arthroplasty.

Multicenter studies providing a larger number of patients with a standardized definition of the extent of resection will hopefully provide answers regarding the clinical outcome of the various reconstructive procedures. Organizing a pelvic tumor study group similar to the sacral tumor study group [14] could potentially advance the science in this area by offering surgeons the opportunity to work closely with material scientists, bioengineers, as well as manufacturers to develop techniques that can potentially improve the quality of life for these patients.