TANTALUM METAL IN ACETABULAR REVISIONS

Abstract

Preliminary results using Trabecular Metal (TM) acetabular component (made of tantalum) in primary and in revision total hip arthroplasty are encouraging in few published papers in the literature.

Patients and Methods: The outcome and survivorship of a TM revision uncemented acetabular cup were assessed in 85 consecutive patients (Male 48, Female 37, mean age 70,9 years, range 54–92) undergoing revision THA in the time period from 13.5.2004 to 8.6.2006. Years from previous operation to revision arthroplasty was in average of 10,0 years (range 1–23). Acetabular bone defects were assessed using Paprosky grading system. Monoblock TM cup was used in 26 operations(Paprosky grade I=13; grade IIa=1; Grade IIb=6 and Grade IIc=6). Modular revision TM cup was used in 59 operations (Paprosky grade I=7; Grade IIa=5; Grade Ibis=15;Grade IIc=24; Grade IIIa=5 and Grade IIIb=3). 55 allografts (femoral heads) were used to fill bone defects in 39 acetabulums. TM augment was needed in 4 operations. In 17 operations also the femoral component was revised. Seven of these operations were re-revision operations. Full weight-bearing was allowed after 44 operations, partial weight-bearing after 37 operations and no weight-bearing after 4 operations. In four operations, where TM cup was initially tried to use, the fixation was found to be insufficient. Consequently, the method of revision was changed either to plating and TM-cup (Paprosky grade IIIB, n=2) or protection cup-system (Paprosky grade IIc, n=2).

Results: Subjectively, the patients were satisfied with this operation at the follow-up (mean 14 months, range 3–26). 58 (68%) patients were painless and 72 (85%) patients walked without any support. X-ray studies showed good TM-cup fixation into acetabular host bone and bone defect filling in 84 out of 85 cases in this short follow-up.

Complications: 7 dislocations, 1 deep infection and 1 sciatic nerve injury. These complications were concentrated to alcoholic and patients with many other health problems.

Conclusion: TM implant has very good primary fixation properties in host bone. The cup shows reliable ingrowths and defect filling with host bone. Our good short-term results with TM-cup are similar to the few previously published papers. Further clinical investigation is needed to show the durability and functionality of this new prosthetic material.