J Orthop Res. 2022 Mar 6. doi: 10.1002/jor.25318. Online ahead of print.
ABSTRACT
Forced external rotation is hypothesized as the key mechanism of syndesmotic ankle injuries, inducing a three-dimensional deviation from the normal distal tibiofibular joint alignment. However, current diagnostic imaging modalities are impeded by a two-dimensional assessment, without considering ligamentous stabilizers. Therefore, our aim is three-fold: (1) to construct an articulated statistical shape model of the normal distal tibiofibular joint with inclusion of ligamentous morphometry, (2) to investigate the effect of weightbearing on the distal tibiofibular joint alignment and (3) to detect differences in predicted syndesmotic ligament length of patients with syndesmotic lesions with respect to normative data. Training data comprised non-weightbearing CT scans from asymptomatic controls (N= 76), weightbearing CT scans from patients with syndesmotic ankle injury (N = 13) and their weightbearing healthy contralateral side (N = 13). Path and length of the syndesmotic ligaments were predicted using a discrete element model, wrapped around bony contours. Statistical shape model evaluation was based on accuracy, generalization and compactness. The predicted ligament length in patients with syndesmotic lesions was compared to healthy controls. With respect to the first aim, our presented skeletal shape model described the training data with an accuracy of 0.23 +/- 0.028 mm. Mean prediction accuracy of ligament insertions was 0.53 +/- 0.12 mm. In accordance to the second aim, our results showed an increased tibiofibular diastasis in healthy ankles after weight-bearing. Corcerning our third aim, a statistically significant difference in anterior syndesmotic ligament length was found between ankles with syndesmotic lesions and healthy controls (p = 0.017). There was a significant correlation between presence of syndesmotic injury and the positional alignment beween the distal tibia and fibula (r = 0.873, p < 0,001). Clinical Significance: Statistical shape modelling combined with patient-specific ligament wrapping techniques can facilitate the diagnostic workup of syndesmosic ankle lesions under weightbearing conditions. In doing so, an increased anterior tibiofibular distance was detected, corresponding to an ‘anterior open-book injury’ of the ankle syndesmosis as a result of anterior inferior tibiofibular ligament elongation/rupture. This article is protected by copyright. All rights reserved.
PMID:35249244 | DOI:10.1002/jor.25318
