Introduction Osteonecrosis of femoral head (ONFH) leads to hip osteoarthritis (HOA); among joint preserving treatments (JPT), the role of core decompression (CD) is still debated. We assessed the efficacy of CD compared with all other JPT in delaying the natural osteonecrosis evolution to HOA. Sources of data Following the PRISMA checklist, the Medline and Scopus databases were searched. Fifteen- to 70-year-old subjects with ONFH with a minimum follow-up of 24 months were considered. The outcomes evaluated were patient clinical status, radiographic progression and total hip arthroplasty (THA) or further surgery (FS) need. Risk ratio (RR) was calculated for every outcome reported. RCT, CCT and prospective studies were included. Areas of agreement A total of 12 studies (776 patients) met the inclusion criteria. Clinical outcome (RR = 1.14; 95% CI 0.58–2.32; P = 0.05), radiographic progression (RR = 1.64; 95% CI 1.14–2.35; P = 0.05) and the need for THA/FS (RR = 1.52; 95% CI 0.95–2.45; P = 0.05) suggested a slight superiority of other JPT compared with CD. Areas of controversy High heterogeneity of the primary investigations was the main limitation of our study. Growing points The efficacy and effectiveness of core decompression for ONFH are, at best, no better than other joint preserving strategies. The more recent scientific evidence seems to suggest that such procedure is less successful than other joint preserving strategies. Areas timely for developing research Further studies are needed to identify the best therapeutic approach to the ONFH.

Subtalar arthroereisis has been reported as a minimally-invasive, effective and low-risk procedure in the treatment of flatfoot mainly in children but also in adults. It has been described as a standalone or adjunctive procedure, and is indicated in the treatment of flexible flatfoot, tibialis posterior tendon dysfunction, tarsal coalition and accessory navicular syndrome. Different devices for subtalar arthroereisis are currently used throughout the world associated with soft-tissue and bone procedures, depending on the surgeon rather than on standardised or validated protocols. Sinus tarsi pain is the most frequent complication, often requiring removal of the implant. To date, poor-quality evidence is available in the literature (Level IV and V), with only one comparative non-randomised study (Level II) not providing strong recommendations. Long-term outcome and complication rates (especially the onset of osteoarthritis) are still unclear. Cite this article: EFORT Open Rev 2017;2:438–446. DOI: 10.1302/2058-5241.2.170009

Background: Weightbearing computed tomography (WBCT) is a useful tool for the assessment of hindfoot alignment (HA). Foot ankle offset (FAO) is a recently introduced parameter, determined from WBCT images using semiautomatic software. The aim of this study was to determine the clinical relevance and reproducibility of FAO for the evaluation of HA. Methods: A prospective comparative study was performed on consecutive patients requiring bilateral WBCT between September 2017 and April 2018. Based on the clinical assessment of HA, patients were divided into 3 groups: (1) normal alignment group (G1), (2) valgus (G2), and (3) varus (G3). FAO and long axial view (HACT) were measured on WBCT images, and the groups were compared. The reproducibility of FAO and HACT was determined through intraclass correlation coefficients (ICCs). Regression analysis was performed to investigate the correlation between the 2 methods. Overall, 249 feet (126 patients) were included (G1 = 115, G2 = 78, and G3 = 56 feet). Results: The mean values for FAO and HACT were 1.2% ± 2.8% and 3.9 ± 3.1, respectively, in G1; 8.1% ± 3.7% and 9.7 ± 4.9 in G2; and −6.6% ± 4.8% and −8.2 ± 6.6 in G3. Intra- and interobserver reliability was 0.987 and 0.988 for FAO and 0.949 and 0.949 for HACT, respectively. There was a good linear correlation between HACT and FAO ( R² = 0.744), with a regression slope of 1.064. Conclusions: WBCT was a useful method for the characterization of HA. FAO was reproducible and correlated well with physical examination. Level of Evidence: Level II, prospective comparative study.

Varus hindfoot deformity may increase the risk of chronic lateral ankle instability (CLAI). Our aim was to analyze hindfoot alignment (HFA) in patients with CLAI using weight-bearing cone beam computed tomography (WBCT) to assess this risk. This retrospective, comparative analysis was carried out using an existing WBCT database (Talas, CurveBeam LLC), including data sets for 370 consecutive feet (189 patients) obtained between July 2016 and October 2018 at a single institution. The software provided semiautomated measurement of HFA, given as foot ankle offset (FAO). Univariate analysis was conducted to compare feet with and without CLAI against sex, age, body mass index, and FAO. Significant variables were included in a multivariable logistic model with random effects to take into account correlation between feet of the same patient. Forty-three feet had CLAI (34 patients). FAO (P = .0009) was significant for CLAI by univariate analysis. Mean FAO was −2.2% ± 5.5% (varus) and + 2.6% ± 4.7% (valgus) with and without CLAI history, respectively. Multivariable logistic regression adjusted for sex and age demonstrated a 35% increased odds ratio (OR) of CLAI per 1% reduction in FAO value (varus) (adjusted OR=0.64, 95% confidence interval [CI]: 0.49-0.84; P = .001) and no significant effect of sex (adjusted OR=0.52; P = .617) or age (adjusted OR=0.94; P = .165) after adjustment for FAO. A positive relationship was found between varus HFA and the risk to have CLAI. Systematic recording of FAO measurements from WBCT images along with clinical data regarding CLAI history proved successful at quantifying the risk of CLAI. Level III, retrospective cohort study.

Background: Semiautomatic 3-dimensional (3D) biometric weightbearing computed tomography (WBCT) tools have been shown to adequately demonstrate the relationship between the center of the ankle joint and the tripod of the foot. The measurement of the foot and ankle offset (FAO) represents an optimized biomechanical assessment of foot alignment. The objective of this study was to evaluate the correlation between FAO and traditional adult acquired flatfoot deformity (AAFD) markers, measured in different planes. We hypothesized that the FAO would significantly correlate with other radiographic markers of pronounced AAFD. Methods: In this retrospective comparative study, we included 113 patients with stage II AAFD, 43 men and 70 women, mean age of 53.5 (range, 20-86) years. 3D coordinates (x, y, and z planes) of the foot tripod (most plantar voxel of the first and fifth metatarsal heads, and calcaneal tuberosity) and the center of the ankle joint (most proximal and central voxel of the talar dome) were assessed by 2 blinded and independent fellowship-trained orthopedic foot and ankle surgeons. The FAO was automatically calculated using the 3D coordinates by dedicated software. Multiple WBCT parameters related to the severity of the deformity in the coronal, sagittal, and transverse planes were manually measured. Results: We found overall good to excellent intra- (range, 0.75-0.99) and interobserver (range, 0.73-0.99) reliability for manual AAFD measurements. FAO semiautomatic measurements demonstrated excellent intra- (0.99) and interobserver (0.99) reliabilities. Hindfoot moment arm (HMA) ( P < .00001), subtalar horizontal angle ( P < .00001), talonavicular coverage angle ( P = .00004), and forefoot arch angle ( P = .0001) were the only variables found to significantly influence and correlate with FAO measurements, with an R² value of 0.79. An HMA value of 19.8 mm was found to be a strong threshold predictor of increased values of FAO, with mean values of FAO of 6.5 when the HMA was lower than 19.8 mm and 14.6 when the HMA was equal to or higher than 19.8 mm. Conclusion: We found that 3D WBCT semiautomatic measurements of FAO significantly correlated with some traditional markers of pronounced AAFD. Measurements of FAO were also found to be slightly more reliable than the manual measurements. The FAO offers a simple and more complete biomechanical and multiplanar assessment of the AAFD, representing in a single measurement the 3D components of the deformity. Level of Evidence: Level III, retrospective comparative study.

We investigated the association between hindfoot residual malalignment assessed on weightbearing computed tomography (WBCT) images and the development of periprosthetic cysts (PPCs) after total ankle replacement (TAR). We hypothesized that PPCs would be found predominantly medially in the varus configuration and laterally in the valgus configuration. Cases of primary TAR with available WBCT imaging of the ankle were included in this retrospective study. The location of the PPC was marked and the following volumes were calculated: total (TCV), medial (MCV), central (CCV), and lateral (LCV) cyst volumes. Hindfoot alignment was measured as Foot and Ankle Offset (FAO), with 95% confidence intervals (95% CIs) calculated to define varus (95% CI) groups. Cyst volumes were compared between these 2 groups. The American Orthopaedic Foot & Ankle Society (AOFAS) score at the time of the WBCT was also retrieved. Receiver operating characteristic (ROC) curves were used to determine FAO thresholds for predicting an increased risk of PPC. Forty-eight TARs (mean follow-up, 44.6 months) were included, 81% of which had at least 1 PPC. The mean FAO was 0.12% (95% CI, –1.12 to 1.36). Patients with greater residual malalignment (P < .001) and those with longer follow-up (P < .001) presented with increased TCV. In varus cases, the MCV was greater than the LCV (P = .042), with a threshold FAO value of −2.75% or less predicting an increased MCV. In valgus cases, the LCV was greater than the MCV (P = .049), with a FAO threshold value of 4.5% or more predicting an increased LCV. In this series, the PPC volume after primary TAR significantly correlated with postoperative hindfoot malalignment and longer follow-up. Level III, retrospective comparative series.