Hello. My name is Connor Delman. I'm an orthopedic surgery resident at UC Davis. Today I will be presenting on tantalum spacer augmentation and hindfoot orthodesis of large bony defects. My co-authors and I would like to thank the AOFAS for the opportunity to present our research today. These are our disclosures. As we know, patients with hindfoot orthodesis in the setting of large osseous defects can result in exceedingly high nonunion rates as well as graft collapse. The use of biocompatible porous tantalum spacers aims to circumvent the limitations of conventional hindfoot fusion techniques while providing a structural option to restore alignment, maintain length, and facilitate union. The purpose of the study was to assess the efficacy, radiographic outcomes, and complication profile associated with tantalum spacer use in hindfoot orthodesis in the setting of large osseous defects. Looking at our methods, we performed a retrospective review of all patients who underwent hindfoot orthodesis augmented with porous tantalum from 2012 to 2020 at a single institution. Patients greater than or equal to 18 years of age with large hindfoot osseous defects treated with either an isolated subtalar orthodesis or tibiotelocalcanearthrodesis were included in the study. These patients all had critically sized defects with greater than 1 to 2 centimeters in length of bone loss or greater than 50% loss in bone circumference. The outcome measures assessed included union rate, time to union, and postoperative complication profile including return to the operating room. Union criteria was assessed using bridging callus, trabeculation, and cortical continuity at the orthodesis metal bone interface. Briefly looking at our surgical technique, you can see that the tibiotelocalcanearthrodesis was performed with a fibular osteotomy utilizing a hindfoot intramedullary nail like you see on the upper right of your screen. Isolated distraction subtalar orthodesis was performed using joint spanning partially and or fully threaded cannulated screws like you see on the bottom right of your screen. The tantalum central core was filled with autograft and orthobiologic proteins such as Infuse or Augment, which was demonstrated on the previous slide. And the foot position infusion included 5 to 10 degrees of hindfoot valgus, neutral dorsiflexion, and 5 to 10 degrees of foot external rotation. Looking at our results on the left side of the screen, you can see the patient characteristics. 17 patients were identified during the study time period who underwent hindfoot orthodesis with the metal implant spacer, 14 of which met inclusion criteria with the use of trabecular augment. And 2 of the 14 patients were ultimately lost to follow-up, resulting in a total of 12 patients, 11 of which were female and 1 patient that was male that were included in the study. There were 9 tibiotelocalcaneofusions and 3 subtalar fusions. The average age of the patients was 59 years old with a mean follow-up of 26 months. All patients underwent autograft, 10 of which had ipsilateral re-autograft, 1 from the tibia, and 1 patient with autograft from the fibula. Four patients had x-rays at final follow-up, and 7 patients had CT scans at final follow-up to assess union. Looking at the outcomes on the right side of the screen, 10 of 12 patients achieved successful orthodesis as evidenced by robust osseous bone bridging, the absence of lucency at the tantalum bone interface, and lack of collapse on imaging. The patients with radiographic evidence of union also lacked clinical symptoms of nonunion, resulting in a union rate of 83% at a mean of 6 months. Three of 12 patients required return to the operating room, 1 for a symptomatic interlock in the intramedullary nail, 1 for a nonunion revision orthodesis, and an additional patient who had a BKA for a chronic infection whose initial presentation was a septic ankle. Patients were weight-bearing and tolerated at a mean of 10 weeks, and transitioned out of a CAM boot at a mean of 30 weeks. In conclusion, obviously this is a limited case series, but it does show that porous tantalum spacers provide a great structural graft option in patients undergoing tibiotelocalcaneal or subtalar fusions in the sitting of large, hindfoot bony defects. The high union rate is indicative of the beneficial biomechanical properties of porous tantalum in promoting stability, bony apposition, ingrowth, and fusion. And ultimately, the method described combining the use of orthobiologics, autograft, and adequate biomechanical stabilization can produce reliable results for a complex clinical problem. We'd like to thank you for your time and giving us the opportunity to present our research findings today. Thank you.

Connor Delman

orthopedic surgery resident

tantalum spacer augmentation

hindfoot orthodesis

large bony defects