Long-Term Survivorship of INBONE II Total Ankle Arthroplasty

As total ankle arthroplasty (TAA) use evolves, understanding implant longevity and survivorship expectations has become critical for patient counseling and decision making. The purpose of this study was to determine the long-term survivorship of the INBONE II TAA.

Patients enrolled in a prospective single-institution TAA registry with minimum 10-year follow-up after INBONE II TAA were retrospectively identified. Chart review captured operative data, prior and concomitant surgeries, reoperations, and revision details. Pre- and postoperative radiographs were measured to assess alignment and periprosthetic lucency or osteolysis. Survivorship was determined by incidence and timing of metal component revision (MCR). Data were stratified by those who failed (MCR) and those who did not. Of 180 TAAs, 74 ankles (71 patients) met inclusion criteria.

Mean age at surgery was 60.9 years (38.7-78.4), with median 10.4 years of follow-up (IQR 9.8, 11.1). Survivorship at minimum 10 years was 93.2% (95% CI: 87.1%-99.3%). Overall reoperation rate was 16.9%. Peri-implant lucency was found in 28.4% of tibias (21) and 13.5% of taluses (10); cysts were noted in 21.6% of tibias and 12.2% of taluses. The MCR rate was 6.8% (3 talus, 2 both components), secondary to failure of ingrowth (2), osteolysis/polyethylene wear (2), and infection (1). Patients who underwent MCR exhibited numerically greater preoperative varus talar tilt (9.6 vs 2.9 degrees) and varus tibiocalcaneal angle (-5.6 vs 9.1 degrees), although these differences were not statistically significant (P = .25 and .07, respectively). They also showed larger changes from pre- to postoperative alignment in tibiotalar and distal tibial angles compared with nonfailures (-16.2 vs 0.2 degrees, P = .11; -7.3 vs -0.2 degrees, P = .07), which likewise were not statistically significant.

Ten-year survivorship of INBONE II TAA was 93% in this cohort. Despite periprosthetic osteolysis and/or peri-implant lucency, the reoperation rate was low. Although the small number of failures prevented statistically significant conclusions, radiographic patterns suggest possible higher risk of failure in those with greater varus deformity.