Background: In progressive collapsing foot deformity (PCFD), hind- and midfoot deformities can be hard to characterize based on weightbearing plain radiography. Semiautomated 3-dimensional (3D) measurements derived from weightbearing computed tomography (WBCT) scans may provide a more accurate deformity assessment. In the present study, automated 3D measurements based on WBCT were used to compare hindfoot alignment of healthy individuals to patients with PCFD. Methods: The WBCT scans of 20 patients treated at our institution with either a flexible (N = 10) or rigid (N = 10) PCFD were compared with the WBCT scans of a control group of 30 healthy individuals. Using semiautomated image analysis software, from each set of 3D voxel images, we measured the talar tilt (TT), hindfoot moment arm (HMA), talocalcaneal angle (TCA; axial/lateral), talonavicular coverage (TNC), and talocalcaneal overlap (TCO). The presence of medial facet subluxation as well as sinus tarsi/subfibular impingement was additionally assessed. Results: With the exception of the TCA (axial/lateral), the analyzed measurements differed between healthy individuals and patients with PCFD. The TCA axial correlated with the TNC in patients with PCFD. An increased TCO combined with sinus tarsi impingement raised the probability of predicting a deformity as rigid. Conclusion: Using 3D measurements, in this relatively small cohort of patients, we identified relevant variables associated with a clinical presentation of flexible or rigid PCFD. An increased TCO combined with sinus tarsi impingement raised the probability of predicting a deformity as rigid. Such WBCT-based markers possibly can help the surgeon in decision-making regarding the appropriate surgical strategy (eg, osteotomies vs realignment arthrodesis). However, prospective studies are necessary to confirm the utility of the proposed parameters in the treatment of PCFD. Level of Evidence: Level III, case-control study.

Introduction: Auto-generated 3-dimensional (3D) measurements based on weightbearing cone-beam computed tomography (CT) scan technology may allow for a more accurate hind- and midfoot assessment. The current study evaluated the reliability and clinical relevance of such measurements in patients with posttraumatic end-stage ankle osteoarthritis. Methods: Seventy-two patients treated at our institution for posttraumatic end-stage ankle osteoarthritis, with available weightbearing conventional radiographs and a cone-beam CT scan, were analyzed. Twenty healthy individuals aged between 40 and 70 years served as controls. Seven variables were measured on weightbearing conventional radiographs (2D) and compared to 3D measurements that were based on reconstructions from weightbearing cone-beam CT scans. The reliability of each measurement was calculated and subgroups formed according to commonly observed deformities. Results: Inter- and intraobserver reliability was superior for 3D compared to 2D measurements. The accuracy of 3D measurements performed on osteoarthritic ankles was similar to 3D measurements performed on healthy individuals. Thirty-three of the 72 included patients (46%) evidenced an inframalleolar compensation of a supramalleolar/intra-articular ankle deformity (78% = varus compensation; 22% = valgus compensation), whereas 24 of those 72 patients (33%) showed no compensation or a further increase of a supramalleolar/intra-articular ankle deformity (67% = varus deformity; 33% = valgus deformity). Conclusion: Auto-generated 3D measurements of the hind- and midfoot were found to be reliable in both healthy individuals and patients with posttraumatic end-stage ankle osteoarthritis. Such measurements may be crucial for a detailed understanding of the location and extent of hindfoot deformities, possibly impacting decision making in the treatment of end-stage ankle osteoarthritis. Level of Evidence: Level III, comparative study.

Background: A reliable assessment of the ankle using weightbearing radiography remains challenging. Semiautomated 3-dimensional (3D) measurements derived from weightbearing computed tomography (WBCT) scans may provide a more reliable approach. Methods: Thirty healthy individuals without any foot and ankle disorder were analyzed. We assessed 6 widely used ankle parameters (4 angles and 2 distances) using either semiautomated 3D (based on WBCT scans) or traditional 2-dimensional (2D; based on conventional radiographs) measurements. The reliability and discrepancy between both techniques were compared using intraclass correlation coefficients and the Bland-Altman method. Results: Five of 6 variables showed a lower reliability when derived from 2D measurements. The mean of 3 variables differed between the techniques: the 3D technique assessed that the talonavicular coverage angle was 18.9 degrees higher, the axial talocalcaneal angle was 5.5 degrees higher, and the talocalcaneal overlap was 3.7 mm lower when compared with 2D measurements. Conclusion: Semiautomated 3D measurements derived from WBCT scans provide more reliable information on ankle alignment compared with 2D measurements based on weightbearing radiographs. Future studies may show to what extent these parameters could contribute to current diagnostic algorithms and treatment concepts. Level of Evidence: Not applicable.

Level IV, prospective cohort study.

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.