An Objective Computational Method to Quantify Ankle Osteoarthritis From Low-Dose Weightbearing Computed Tomography.

Background: The treatment of ankle osteoarthritis (OA) varies depending on the severity and distribution of the associated joint degeneration. Disease staging is typically based on subjective grading of appearance on conventional plain radiographs, with reported subpar reproducibility and reliability. The purpose of this study was to develop and describe computational methods to objectively quantify radiographic changes associated with ankle OA apparent on low-dose weightbearing CT (WBCT). Methods: Two patients with ankle OA and 1 healthy control who had all undergone WBCT of the foot and ankle were analyzed. The severity of OA in the ankle of each patient was scored using the Kellgren-Lawrence (KL) classification using plain radiographs. For each ankle, a volume of interest (VOI) was centered on the tibiotalar joint. Initial computation analysis used WBCT image intensity (Hounsfield units [HU]) profiles along lines perpendicular to the subchondral bone/cartilage interface of the distal tibia extending across the entire VOI. Graphical plots of the HU distributions were generated and recorded for each line. These plots were then used to calculate the joint space width (JSW) and HU contrast. Results: The average JSW was 3.89 mm for the control ankle, 3.06 mm for mild arthritis (KL 2), and 1.57 mm for severe arthritis (KL 4). The average HU contrast was 72.31 for control, 62.69 for mild arthritis, and 33.98 for severe arthritis. The use of 4 projections at different locations throughout the joint allowed us to visualize specifically which quadrants have reduced joint space width and contrast. Conclusion: In this technique report, we describe a novel methodology for objective quantitative assessment of OA using JSW and HU contrast. Clinical Relevance: Objective, software-based measurements are generally more reliable than subjective qualitative evaluations. This method may offer a starting point for the development of a more robust OA classification system or deeper understanding of the pathogenesis and response to ankle OA treatment.

Does tibialis posterior dysfunction correlate with a worse radiographic overall alignment in progressive collapsing foot deformity? A retrospective study.

BACKGROUND: Posterior Tibial Tendon (PTT) dysfunction is considered to have an important role in Progressive Collapsing Foot Deformity (PCFD). The objective of our study was to assess the relationship between PTT status and three-dimensional foot deformity in PCFD. METHODS: Records from 25 patients with PCFD were included for analysis. The PTT was considered deficient in patients with a positive single heel rise test or a deficit in inversion strength. Three-dimensional foot deformity was assessed using the Foot and Ankle Offset (FAO) from Weight-Bearing-CT imaging. Hindfoot valgus, midfoot abduction and medial longitudinal arch collapse were assessed on X-Rays using hindfoot moment arm, talonavicular coverage angle and Meary's angle respectively. Deland and Rosenberg MRI classifications were used to classify PTT degeneration. RESULTS: PCFD with PTT deficit (13/25) had a mean FAO of 7.75 + /- 3.8% whereas PCFD without PTT deficit had a mean FAO of 6.68 + /- 3.9% (p = 0.49). No significant difference was found between these groups on the hindfoot moment arm and the talonavicular coverage angle (respectively p = 0.54 and 0.32), whereas the Meary's angle was significantly higher in case of PCFD with PTT deficit (p = 0.037). No significant association was found between PTT degeneration on MRI and FAO. CONCLUSION: PCFD associated three-dimensional deformity, hindfoot valgus and midfoot abduction were not associated with PTT dysfunction. PTT dysfunction was only associated with a worse medial longitudinal arch collapse in our study. Considering our results, it does not appear that PTT is the main contributor to PCFD. LEVEL OF EVIDENCE: Level III, Retrospective Comparative Study.

Multiplanar instability of the first tarsometatarsal joint in hallux valgus and hallux rigidus patients: a case-control study.

BACKGROUND: Hypermobility of the first ray has been considered associated with various forefoot diseases including hallux valgus (HV) and hallux rigidus (HR). Weightbearing CT scan can be a reliable method for analysis of the first tarsometatarsal (TMT) joint in axial, sagittal, and coronal planes. Our objective was to comparatively investigate signs of instability of the first TMT joint on weightbearing CT between three groups (control, HV, and HR). METHODS: In this single-centre, retrospective, case-control study, 27 HV patients (30 feet; mean age 54.2 years), 26 HR patients (30 feet; mean age 56.6 years), and 30 controls (30 feet; mean age; 43 years) were enrolled. Measurements of signs of instability were performed in multiplanes including first TMT angle, dorsal translation of the first metatarsal (M1) at the first TMT joint, plantar distance between the medial cuneiform (C1) and M1 in sagittal plane, hallux valgus angle (HVA), intermetatarsal angle (IMA) in axial plane, rotational profiles of C1 and M1 in coronal plane. Analysis of variance (ANOVA) test and chi-square test were performed to compare each parameter between the three groups. Interobserver reliabilities were assessed using interclass correlation coefficients (ICCs). RESULTS: The HV group had significantly increased first TMT angle (0.23° in controls, 1.15° in HV, 0.19° in HR, p < 0.001), HVA (7.52°, 33.50°, 11.21°, p < 0.001), IMA (9.46°, 16.98°, 11.87°, p < 0.001), C1-M1 angle (22.44°, 29.46°, 23.74°, p < 0.001), and rotational profile of the distal M1 (7.06°, 17.88°, 9.85°, p < 0.001) compared with the control and HR groups. Dorsal translation of M1 (23% in controls, 63% in HV, 70% in HR, p < 0.001) was frequently found in the HV and HR groups with significantly increased plantar distance (0.37 mm, 1.14 mm, 1.46 mm, p < 0.001) compared with controls. CONCLUSIONS: Multiplanar instability of the first TMT joint was confirmed using weightbearing CT in HV and HR groups compared with controls. HV group demonstrated instability mainly in sagittal and axial planes; HR group had sagittal instability predominantly. Our measurement of rotational instability at the first TMT joint was not able to detect differences between groups. A surgical correction of the instability at the first TMT joint can be an option to address HV and HR. CLINICAL RELEVANCE: First ray hypermobility at the first TMT joint is an important consideration when addressing HV and HR, a surgical correction of the instability at the first TMT joint should be taken in consideration as an option.

Deformity Correction in Ankle Osteoarthritis Using a Lateral Trans-Fibular Total Ankle Replacement: A Weight-Bearing CT Assessment.

Background: Ankle osteoarthritis (AO) is often secondary to prior trauma and frequently presents with joint deformity. Total ankle replacement (TAR) has been shown as a viable surgical option to reduce pain, improve function, and preserve ankle joint range of motion. The standard TAR uses an anterior approach, but recently a lateral trans-fibular approach has been developed. Our aim was to determine if the lateral TAR was able to correct alignment and improve patient reported outcomes (PROs) in patients with end-stage AO. Methods: This IRB-approved, retrospective comparative study included 14 consecutive patients that underwent lateral trans-fibular approach TAR for end-stage AO. All patients had received pre-and post-operative WBCT imaging on the affected foot and ankle. Using multiplanar reconstruction of WBCT images, measures of coronal and sagittal plane ankle alignment: Foot and Ankle Offset (FAO), Talar Tilt Angle (TTA), Hindfoot Moment Arm (HMA), and Lateral Talar Station (LTS) were performed. PROs were collected pre- and postoperatively at the latest clinical follow-up. Results: All patients demonstrated a significant deformity correction in all measurements performed: FAO (7.73%-3.63%, p=0.031), HMA (10.93mm - 5.10mm, p=0.037), TTA (7.9o-1.5o, p=0.003), and LTS (5.25mm-2.83mm, p=0.018). Four of the PROs measured exhibited significant improvement postoperatively, the Tampa Scale for Kinesiophobia (TSK) (42.7-34.5, p=0.012), PRO-MIS Global Physical Health (46.1-54.5, p=0.011), EFAS (5-10.3, p=0.004), and FAAM Daily Living (60.5-79.7, p=0.04). Multivariate analysis assessing the influence of deformity correction in the improvements of PROs found that PROMIS Global Physical Health was significantly associated with improvements in FAO and LTS, TSK associated with HMA, and FAAM Daily Living with FAO and TTA (p<0.05). Conclusion: The results of this retrospective comparative cohort study suggest that the lateral trans-fibular TAR can correct different aspects of AO deformity. The method also impacted PROs, particularly TSK, PROMIS Global Physical Health, EFAS, and FAAM Daily Living. Direct correlation between some of the deformity correction measurements and the significantly improved PROs was found. The obtained data could help surgeons when making treatment decisions and be the base for comparative prospective studies. Level of Evidence: III.