POROUS TANTALUM METAPHYSEAL CONES FOR LARGE TIBIAL BONE DEFECTS IN REVISION TOTAL KNEE ARTHROPLASTY: MID-TERM SURVIVORSHIP, PATIENT SATISFACTION, AND FUNCTIONAL OUTCOMES

Porous tantalum metaphyseal cones facilitate the reconstruction of large tibial bone defects during revision total knee arthroplasty (TKA). However, the effects of these complex reconstructions on intermediate-term component survivorship and functional outcomes remain unknown. The objectives of this study were to report on component survivorship, patient satisfaction, functional outcomes, radiographic osseointegration and complications of revision TKA using porous tantalum metaphyseal tibial cones at mid-term follow-up. This study included 130 patients with an average age of 66.4 (range, 35.2 to 86.1 years) undergoing revision TKAs using porous tantalum metaphyseal tibial cones. Study patients had undergone a mean number of 2.2 prior surgical procedures (range, 1 to 8 previous procedures) on the failed TKA. The indications for surgery included aseptic loosening (n=67), global knee instability (n=16), osteolysis (n=15), second-stage revision for infection (n=28), single-stage revision for infection (n=2), periprosthetic fracture (n=2) and tibial component fracture (n=1). The study included patients with Anderson Orthopaedic Research Institute (AORI) bone classification system type IIA (n=40), IIB (n=45), and III (n=45) tibial bone defects. The average follow-up time was 4.86 years (range, 2 to 13.9 years). Survivorship with cone revision as the endpoint was 100%, and survivorship with reoperation for any reason as the endpoint was 88.5%. In total, 13 patients required reoperations, which included seven patients with acute infections requiring debridement, implant retention and antibiotics; three patients with instability requiring increased levels of constraint; three patients with quadriceps tears requiring repair/reconstruction, and two patients with traumatic injuries requiring fracture fixation or increased level of constraint for ligamentous injury. There were no intraoperative complications during cone or implant insertion. At final follow-up, the mean patient satisfaction score was 79.4 ± 11.3 and mean Forgotten Joint Scores was 59.3 ± 16.7. Compared to preoperative values, there were statistically significant improvements in the mean University of California at Los Angeles score (2.9 ± 0.7 vs 5.5 ± 0.7 respectively, p and mean Oxford Knee Score (14.9 ± 3.8 vs 39.2 ± 5.1 respectively, p All porous tantalum metaphyseal cones showed radiographic evidence of osteointegration without any subsidence or loosening at final follow-up. Porous tantalum metaphyseal tibial cones in revision TKA facilitated robust reconstructions of severe tibial defects with excellent survivorship at mid-term follow-up. The most common reasons for reoperation included acute prosthetic joint infections, instability due to inadequate TKA constraint, and quadriceps tendon tears. These complex reconstructions were associated with high-levels of patient satisfaction, improvements in functional performance, and reliable radiographic osseointegration at mid-term follow-up.