Abstract:[Objective] To compare the clinical outcomes of the fully threaded headless compression screws (FTCS) versus intramedul-lary nails (IMN) used as internal fixations in tibiotalocalcaneal arthrodesis (TTCA) for end-stage ankle and subtalar arthropathy. [Methods]A retrospective study was conducted on 52 patients (52 feet) who received TTCA for end-stage ankle and subtalar osteoarthritis in our hospi-tal from 2018 to 2022. Based on the preoperative patient-doctor discussion, 28 patients had tibiotalocalcaneal joints fixed with multiple FTC-Ss, while the remaining 24 patients were fixed with IMN. The documents regarding to perioperative period, follow-up and images were com-pared between the two groups. [Results] All the patients in both cohorts had TTCA performed successfully, without statistically significantdifferences between the two groups in terms of operation time, total length of incision, intraoperative blood loss, number of intraoperative fluo-roscopy, ambulation time, incision healing grade, ratio of percutaneous nerve injury, and hospital stay (P>0.05). The follow-up period lastedfor more than 12 months, and the FTCS group resumed full weight-bearing activity significantly earlier than the IMN group [(125.7±38.9)days vs (149.2±23.6) days, P=0.013]. The VAS scores significantly decreased at the last follow-up compared with that preoperatively (P<0.05), while the AOFAS scores significantly increased at the last follow-up compared with that 3 months postoperatively in both groups (P<0.05). The FTCS group proved significantly superior to the IMN group in term of AOFAS score 3 month postoperatively and at the latest fol-low-up [(61.5±4.8) vs (57.3±7.0), P=0.015; (75.2±6.7) vs (70.7±8.5), P=0.036]. As for imaging, the tibiocalcaneal angle (TCA), calcaneal off-set (CO) and internal arch angle (IAA) significantly improved in both groups at the latest follow-up compared with those preoperatively (P<0.05), whereas which were not statistically significant between the two groups at any time points accordingly (P>0.05). However, the FTCSgroup got bony fusion on images significantly earlier than the IMN group (P<0.05). [Conclusion] The FTCS achieved considerably betteroutcome in terms of AOFAS scores, time to regain full weight bearing activity, and bony fusion time on images over the IMN for end-stage an-kle and subtalar arthropathy in this paper.