Background

Large bone loss and frequently irradiated existing bone make reconstructing metastatic and other nonprimary periacetabular tumors challenging. Although existing methods are initially successful, they may fail with time. Given the low failure rates of porous tantalum acetabular implants in other conditions with large bone loss or irradiated bone, we developed a technique to use these implants in these neoplastic cases where others might fail.

Description of Technique

After local tumor curettage, a large uncemented tantalum shell (sometimes with tantalum augments) was fixed to remaining bone using numerous screws. When substantial medial bone loss was present, an antiprotrusio cage was placed over the top of the cup and secured to remaining ilium and ischium.

Patients and Methods

We retrospectively reviewed 20 patients who underwent THAs for neoplastic bone destruction with the described technique. Their mean age was 60 years (range, 22–80 years). We recorded pain and ambulatory status, pain medication use, and Harris hip scores. We assessed for progressive radiolucent lines and component migration on followup radiographs. Eleven of the 20 patients died at a mean of 17 months after surgery. The minimum followup for surviving patients was 26 months (mean, 56 months; range, 26–85 months).

Results

Harris hip scores improved from a mean 32 preoperatively to a mean 74 postoperatively. We observed no cases of progressive radiolucent lines or component migration. Complications included one perioperative death, two superficial infections, one deep vein thrombosis, and one dislocation.

Conclusion

Our initial experience has made tantalum reconstruction our preferred method for dealing with major periacetabular neoplastic bone loss. Additional studies comparing this technique with alternatives are required.

Level of Evidence

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background

A number of recent reports have described novel failure mechanisms of metal-on-metal bearings in total and resurfacing hip arthroplasty. Hip arthroplasties with metal-on-metal articulations are also subject to the traditional methods of failure seen with different bearing couples. There is currently little information in the literature to help guide timely clinical evaluation and management of these patients.

Questions/purposes

We therefore describe the (1) clinical presentations; (2) reasons for failure; (3) operative findings; and (4) histologic findings in patients with failed metal-on-metal hip arthroplasties.

Methods

We retrospectively identified all 37 patients (37 hips) with metal on metal total hip or resurfacing arthroplasties who underwent revision over the past 3 years at our institution. Relevant clinical, radiographic, laboratory, intraoperative, and histopathologic findings were analyzed for all patients.

Results

Of the 37 patients, 10 were revised for presumed hypersensitivity specific to the metal-on-metal articulation. This group included eight patients with tissue histology confirming chronic inflammation with lymphocytic infiltration, eight with aseptic loosening of a monoblock screwless uncemented acetabular component, two with iliopsoas impingement associated with a large-diameter femoral head, and three with femoral neck fracture after resurfacing arthroplasty; the remainder of the patients were revised for infection, instability, component malposition, and periprosthetic fracture.

Conclusions

Increased awareness of the modes of failure will bring to light the potential complications particular to metal-on-metal articulations while placing these complications into the context of failures associated with all hip arthroplasties. This novel clinical information should be valuable for the practicing surgeon faced with this patient population.

Level of Evidence

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Management of large bone defects in total knee arthroplasty (TKA) usually has involved modular prostheses with metal augments, structural allografts, and megaprostheses. We retrospectively reviewed the outcome of treatment of major bone defects for 74 patients (79 knees) who had revision TKAs with structural allografts; nine patients were lost to followup before 5 years, leaving 65 patients (70 knees, or 88%) followed for a minimum of 5 years or until revision or death. Medical records, radiographs, patient surveys, and correspondence were used for all data. Sixteen patients (22.8%) had failed reconstructions and underwent additional revision surgery; eight of the 16 were secondary to allograft failure, three were secondary to failure of a component not supported by allograft, and five were secondary to infection. In patients not requiring revision surgery, the Knee Society score improved from 49 preoperatively to 87 postoperatively. We observed revision-free survival of 80.7% (95% confidence interval, 71.7–90.8) at 5 years and 75.9% (95% confidence interval, 65.6–87.8) at 10 years. Our data support the selective use of structural allograft for large cavitary defects encountered during TKA. However, the rates of complications and reoperations suggest efforts to improve results or develop more durable alternative methods are warranted for these challenging reconstructions.

Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.