Juric Doria, Donners Ricardo, Harder Dorothee, Burssens Arne, Nüesch Corina, Krähenbühl Nicola
Department of Orthopaedics, University Hospital Basel, Spitalstrasse 21, Basel 4031, Switzerland.
Department of Radiology and Nuclear Medicine, University Hospital Basel, Spitalstrasse 21, Basel 4031, Switzerland.
Foot Ankle Surg. 2025 Apr;31(3):273-277. doi: 10.1016/j.fas.2024.11.003. Epub 2024 Nov 14.
Progressive collapsing foot deformity (PCFD) remains challenging to treat. Surgical planning depends on the amount and complexity of the deformity, which requires accurate differentiation through precise imaging. Weightbearing CT (WBCT) imaging has enhanced the three-dimensional (3D) assessment of PCFD. However, it remains unclear how PCFD findings on WBCT are related to the evaluation of conventional weightbearing radiographs. Therefore, we aimed to (1) compare specific X-ray measurements to corresponding WBCT measurements; (2) evaluate the reliability of X-ray measurements of interest; and (3) investigate whether X-ray measurements can infer osseous impingement in the subtalar joint region identified through WBCT.
Two clinically established measurements were assessed on standardized weightbearing radiographs (manually) as well as on the WBCT datasets (auto-generated): (1) talo-calcaneal overlap (TCO, mm) and (2) talo-navicular coverage (TNC, °). In addition to the measurements, osseous impingement in the subtalar joint region was assessed on WBCT using three criteria, compared both inter- and intra-rater: (1) joint obliteration; (2) cyst formation; and (3) signs of secondary instability. Two of the criteria needed to be fulfilled to confirm subtalar impingement.
While no significant difference between X-ray and WBCT measurements was evident for TCO, significant differences were found for TNC. Inter- and intra-observer reliability was with an intraclass correlation coefficient > 0.9 excellent for both measurements on X-rays. The mean bias of measurement (between X-ray and WBCT) was 0.2 mm for TCO and -22 degrees for TNC. Cohen's Kappa for inter- and intra-rater reliability to assess patients for subtalar instability was > 0.9. The probability to infer subtalar impingement was ≥ 0.85 if TCO was > 15 mm or TNC was > 25 degrees on X-ray.
The examined imaging parameters are reliably assessable through conventional radiographs (TCO/TNC) or WBCT (osseous subtalar impingement). In situations where WBCT is unavailable, X-ray-assessed TCO and TNC can serve as predictors for osseous sinus tarsi impingement. This finding plays a pivotal role in evaluating PCFD patients, aiding in the surgical decision-making process between joint-preserving interventions (e.g., osteotomies) and joint-sacrificing procedures (e.g., realignment fusion).
Level IV, observational study.
进行性塌陷性足畸形（PCFD）的治疗仍然具有挑战性。手术规划取决于畸形的程度和复杂性，这需要通过精确的影像学检查进行准确鉴别。负重CT（WBCT）成像增强了对PCFD的三维（3D）评估。然而，WBCT上PCFD的表现与传统负重X线片评估之间的关系仍不清楚。因此，我们旨在：（1）比较特定的X线测量值与相应的WBCT测量值；（2）评估感兴趣的X线测量的可靠性；（3）研究X线测量是否能推断通过WBCT确定的距下关节区域的骨撞击。
在标准化负重X线片（手动）以及WBCT数据集（自动生成）上评估两项临床既定测量值：（1）距骨-跟骨重叠（TCO，mm）和（2）距骨-舟骨覆盖度（TNC，°）。除了测量外，还使用三个标准在WBCT上评估距下关节区域的骨撞击，在评分者间和评分者内进行比较：（1）关节间隙消失；（2）囊肿形成；（3）继发性不稳定迹象。需要满足其中两个标准才能确认距下撞击。
虽然TCO的X线和WBCT测量值之间没有明显差异，但TNC存在显著差异。观察者间和观察者内的可靠性良好，X线测量的组内相关系数均>0.9。TCO测量值（X线和WBCT之间）的平均偏差为0.2mm，TNC为-22度。评估患者距下不稳定的评分者间和评分者内可靠性的Cohen's Kappa>0.9。如果X线片上TCO>15mm或TNC>25度，则推断距下撞击的概率≥0.85。
通过传统X线片（TCO/TNC）或WBCT（距下骨撞击）可以可靠地评估所检查的成像参数。在无法获得WBCT的情况下，X线评估的TCO和TNC可作为跗骨窦骨撞击的预测指标。这一发现对评估PCFD患者起着关键作用，有助于在保留关节的干预措施（如截骨术）和牺牲关节的手术（如重新排列融合）之间的手术决策过程。
IV级，观察性研究。
