In 1879, Albert described ankle fusion, a technique that at that time was the only option for the treatment of severe ankle lesions, but there has not been much progress in ankle fusion in the last hundred years. Since the 1960s, attention has been focused on ankle fusion from different perspectives: fusion technique, fusion rates, incision or arthroscopic fusion, functional prognosis, gait analysis, and the effect on the ipsilateral hip and knee under long-term follow-up. Recent studies have begun to focus on the ankle joint after fusion compared to the normal population. However, most of the literature is still only level III or IV evidence. Charley J1 noted the importance of compression for ankle fusion in 1951 (level of evidence: level IV), and his advocacy of external fixation fusion has been used for more than 20 years. After the 1970s, the use of internal fixation began to increase, and Moecckel2 et al. concluded that external fixation has a higher rate of nonunion, longer fusion time, and higher risk of infection compared with internal fixation. More recently, it has been argued that circumferential external fixation frames deserve recognition for their advantages of allowing early weight bearing, easy adjustment of deformity, better protection of soft tissues, and avoidance of internal fixation irritation, but it has also been argued that this technique is complex, costly and labor-intensive, and that pin tract infections are common. Studies in the tertiary evidence literature suggest that external fixation is advantageous in the presence of infection, bone defects, ischemic necrosis of the talus, or severe deformity, but higher levels of medical evidence are lacking. Screw fixation has advantages over plate fixation: less soft tissue stripping and better compression. Two crossed screws have been shown to provide stronger fixation than two parallel screws, and cadaveric studies have shown that three screws provide more reliable compression and torsional resistance.5 Autogenous bone grafting of the lateral aspect of the ankle joint after osteotomy of the fibula can provide further ankle stability, and cadaveric studies have shown that T-plates provide the strongest fixation, but require more soft tissue stripping intraoperatively. Arthroscopic fusion of the ankle was proposed by Schneider in 1983 and was supported by others. Arthroscopic fusion has the advantages of short operative time, fusion rates comparable to those of the incisional approach, short hospital stay, and few incisional complications, but studies on the advantages of the above-mentioned arthroscopic approach are only in the tertiary and quaternary literature, and all proponents of the arthroscopic approach agree that proficiency in small arthroscopic techniques and minimal deformity of the diseased ankle are prerequisites for arthroscopic fusion. The optimal position for ankle fusion is currently considered to be neutral dorsiflexion, mild valgus, external rotation (in reference to the healthy side), and a talar position that coincides with the tibial midline or is mildly posteriorly displaced. The clinical results of ankle fusion have been generally satisfactory, with a large body of literature (mostly uncontrolled retrospective studies) from 1960 to the present demonstrating the effectiveness of ankle fusion in relieving pain and improving function. An intermediate follow-up study with a level III evidence rating confirmed that there is still a significant difference in fused ankle function compared to the healthy side.8 Some level III evidence suggests a higher incidence of hindfoot arthritis (especially subtrochanteric arthritis) after ankle fusion, but two papers reported over 20 years of follow-up that more than 60% of patients were satisfied with the treatment despite the high incidence of hindfoot arthritis.9, 10 However, Sheridan et al. Sheridan et al. showed that 77.5% of end-stage ankle patients had preoperative subtalar arthritic lesions.10 There is no evidence that ankle fusion is associated with an increased incidence of ipsilateral or contralateral knee arthritis and metatarsophalangeal arthritis. The gait of patients after ankle fusion usually changes as follows: decreased stride length, slower gait speed, early heel-off ground during the resting weight-bearing phase, anterior tibial tilt during the resting weight-bearing phase, posterior shift of the ground reaction zone on the metacarpal side of the forefoot at the end of the resting weight-bearing phase, increased hip flexion, early knee extension, decreased hindfoot motion, and increased midfoot motion.11 Bayaert et al. suggested that the change in gait increased midtarsal joint shear forces and may contribute to secondary arthritis in the hindfoot. Ankle replacement Despite the ongoing controversy regarding ankle replacement, interest in ankle replacement has increased with the progressive development of foot and ankle surgery as a separate discipline and the continuous improvement of prostheses and the successful performance of hip, knee, shoulder, and elbow replacements. Currently, there are two types of ankle prostheses, two-part and three-part, and the three-part prosthesis is becoming more mainstream because of its movable liner and low osteotomy, but there is no medical evidence comparing the results of the two types of prostheses. Prospective studies on the clinical outcomes of ankle replacements are increasing each year, but there is a lack of long-term follow-up comparisons between the two types of arthroplasty and joint fusion. Current results for the clinical use of next-generation prostheses are that prosthetic replacements are effective in relieving pain and improving foot and ankle function and gait, with acceptable 5-10 year prosthetic survival rates, but are not comparable to hip and knee replacements. A Level III evidence-based meta-analysis synthesizing 10 papers from 1998 to 2005 concluded12 that the 5-year prosthetic survival rate for ankle replacement was 78% and the 10-year prosthetic survival rate was 77%. During follow-up, 7% of cases underwent revision, with loosening and sinking of the prosthesis being the most common reasons for revision; 5% of cases underwent fusion, with loosening and sinking of the prosthesis remaining the predominant reason; and 1% of cases resulted in amputation. In contrast, 39 articles on joint fusion between 1990 and 1997 reported a nonfusion rate of 10% and 9% of patients underwent revision (65% of the reasons for revision were nonfusion); 5% of patients ended up with amputation. The longest reported follow-up for a two-part ankle prosthesis is 9 years.13 Because the outcome of first-generation ankle prostheses has been so disappointing, we cannot yet determine whether second- and third-generation prostheses will suffer the same fate. Level IV medical evidence points to more complications and a longer recovery period in cases of fusion after failed prosthesis replacement, so caution should be exercised when considering arthroplasty for younger patients. Ankle arthroplasty can significantly improve gait and joint mobility compared with fusion, thereby reducing subtalar joint stress, and Soohoo14 et al. noted by Meta-analysis (Level III evidence) that the probability of needing subtalar joint fusion after ankle arthroplasty is lower than that of ankle fusion. Fresh ankle osteochondral transplantation Brage15 et al. reported 11 cases of osteochondral transplantation with a mean follow-up of 33 months, with success in 6 cases, but the level of evidence in this literature was only level IV. The authors of this literature concluded that osteochondral transplantation has some value as an alternative to ankle replacement in younger patients with end-stage ankle arthritis. Ankle distraction Standard procedure: after ankle arthroscopic debridement, the ankle is distracted with an external fixator, 1 mm daily until 5 mm, the hinge is released to allow ankle motion after 6 to 12 weeks, and the external fixation is removed after 15 weeks. Marijnissen16 reported a significant reduction in pain (p<0.0001) and a significant improvement in function (p<0.0001) in 33 patients with a mean follow-up of 2.8 years, but no significant improvement in imaging.17 Ploegmakers17 reported an efficiency of 73% in 25 patients with a follow-up of more than 7 years. Despite the effectiveness of this approach, the relevant data are limited to the literature of grade III or IV. Conclusion There is a lack of controlled studies on long-term follow-up of different procedures for end-stage ankle osteoarthritis. The most commonly used procedures are joint fusion and joint replacement, however, the clinical use of joint replacement is relatively short and physicians lack authoritative evidence for deciding on the surgical approach. The problem is also that clinical outcomes of ankle replacement must be followed for greater than 5 years, or even 15 to 20 years, but after 15 to 20 years, there have been significant innovations in technology and prostheses, and the previous long-term follow-up studies are not very informative. Looking at the current literature, the only conclusion that can be drawn is whether ankle fusion is worth the risk of return to preserve joint mobility when the short-term clinical outcomes of ankle fusion and replacement are comparable. Does ankle replacement reduce the incidence of hindfoot arthritis and improve gait? Are the long-term results promising? The answers to these questions are not yet known.