Subtalar joint anatomy is complex and can vary significantly between individuals.Movement is affected by several adjacent joints, ligaments and periarticular tendons.The subtalar joint has gained interest from foot and ankle surgeons in recent years, but its importance in hindfoot disorders is still under debate.The purpose of this article is to give a general overview of the anatomy, biomechanics and radiographic assessment of the subtalar joint.The influence of the subtalar joint on the evolution of ankle joint osteoarthritis is additionally discussed.Cite this article: EFORT Open Rev 2017;2:309-316. DOI: 10.1302/2058-5241.2.160050

Aims To assess the effect of age on clinical outcome and revision rates in patients who underwent total ankle arthroplasty (TAA) for end-stage ankle osteoarthritis (OA). Methods A consecutive series of 811 ankles (789 patients) that underwent TAA between May 2003 and December 2013 were enrolled. The influence of age on clinical outcome, including the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score, and pain according to the visual analogue scale (VAS) was assessed. In addition, the risk for revision surgery that includes soft tissue procedures, periarticular arthrodeses/osteotomies, ankle joint debridement, and/or inlay exchange (defined as minor revision), as well as the risk for revision surgery necessitating the exchange of any of the metallic components or removal of implant followed by ankle/hindfoot fusion (defined as major revision) was calculated. Results A significant improvement in the AOFAS hindfoot score and pain relief between the preoperative assessment and the last follow-up was evident. Age had a positive effect on pain relief. The risk for a minor or major revision was 28.7 % at the mean follow-up of 5.4 years and 11.0 % at a mean follow-up of 6.9 years respectively. The hazard of revision was not affected by age. Conclusion The clinical outcome, as well as the probability for revision surgery following TAA, is comparable between younger and older patients. The overall revision rate of the Hintegra total ankle is comparable with other three component designs. TAA should no longer be reserved for low demand elderly patients, but should also be recognized as a viable option for active patients of younger age. Cite this article: Bone Joint J 2020;102-B(7):925–932.

Background: Although surgeons have argued that preserving motion at the level of the ankle joint may be crucial for the long-term success in the treatment of end-stage ankle osteoarthritis, there is little evidence regarding the potential of total ankle arthroplasty (TAA) to increase ankle range of motion (ROM). In addition, the effect of a percutaneous heel cord lengthening (HCL) during TAA on ankle motion is poorly understood. Methods: A total of 357 primary TAAs treated with a 3-component device (336 patients, mean age 62.6 [24-85] years) performed between May 2003 and November 2017 were retrospectively analyzed. Sagittal ankle ROM was assessed according to a previously published protocol preoperatively (PreOP), 1 year postoperatively (PostOP), and at the last available follow-up (LastFU). Pain assessed on a visual analog scale (VAS) was assessed at the same time points. The effect of a percutaneous HCL on ankle ROM and VAS for pain was also evaluated. Results: Preoperative ankle ROM increased from mean 31.3 (0-69) to 33.9 (5-65) degrees 1 year postoperatively ( P = .0002) and decreased to 31.9 (5-70) degrees at the LastFU ( P = .007). Percutaneous HCL showed no effect on ankle ROM development after TAA ( P = .141). Ankle ROM improvement after TAA (PreOP to LastFU) was higher in ankles with lower preoperative ankle motion ( P < .0001). A lower ankle ROM at the last follow-up tended to be associated with a higher pain level ( P = .056). Conclusion: Although ankles with a lower preoperative sagittal ROM gained motion, the current data suggest that TAA has little potential to increase the preoperative available ankle motion. In some patients with a high preoperative ankle ROM, a slight decrease of ankle motion was observed postoperatively. Patients with limited ankle motion at long-term follow-up tended toward experiencing higher pain levels. The short- and long-term effect of a percutaneous HCL on ankle ROM following TAA was minimal. Level of Evidence: Level III, retrospective comparative series.

BackgroundGiven the growing number of primary total ankle replacements (TAR), an increase in the number of patients undergoing subsequent revisions might be expected. Achieving a stable and balanced ankle while preserving the remaining bone stock as much as possible is crucial for success in revision TAR. Most reported techniques rely on bulky implants with extended fixation features. Since 2018, we have used a novel, three-component ankle prosthesis for revision that is converted in situ to a fixed-bearing, two-component ankle prosthesis once the components have found their position according to an individual’s anatomy. The results of this novel concept (fixation, revision, pain, or function) have not, to our knowledge, been reported.Questions/purposesWhat are the short-term results with this new revision TAR design, in terms of (1) repeat revision surgery, (2) patient-reported outcomes on the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, (3) pain according to the VAS, and (4) radiographic signs of fixation?MethodsBetween February 2018 and February 2020, we performed 230 TAR surgeries (in 206 patients) for any indication in our clinic. The novel semiconstrained, uncemented Hintermann Series H2© implant was used in 96% (220 of 230) of procedures (201 patients). Fifty-four percent (119 of 220) of these were converted from an existing TAR to H2, which was the focus of the present study. However, only 45% (54 of 119) of these conversions to H2 were eligible for analysis. These patients had a mean age of 63 ± 12 years, and 43% (23 of 54) were women. The median (range) follow-up time was 3.2 years (2.0 to 4.3). The H2 design allows in situ conversion to a fixed-bearing system, with minimal bone resection. It achieves translational and rotational stability while preserving function and supporting the periarticular soft tissues. We defined repeat revision as exchange of one or both metal components, ankle fusion, or amputation and assessed it using a cumulative incidence survivorship estimator. Factors potentially associated with revision were assessed using Cox regression analyses. Clinical and radiologic outcomes were assessed preoperatively and at the most recent follow-up interval. Clinical outcomes included pain on the VAS (average pain during normal daily activity during the past seven days) and AOFAS score. Radiologic outcomes were the tibial articular surface angle, tibiotalar surface angle, talar tilt angle in the coronal plane, and AP offset ratio in the sagittal plane, as well as radiolucent lines and radiographic signs of loosening, defined as change in position greater than 2° of the flat base of the tibia component in relation to the long axis of the tibia, subsidence of the talar component into the talus greater than 5 mm, or change in position greater than 5° relative to a line drawn from the top of the talonavicular joint to the tuberosity of the calcaneus, as seen on plain weightbearing radiographs.ResultsThe cumulative incidence of repeat revision after 1 and 2 years...

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