Premature fusion of craniofacial joints, i.e. sutures, is a major clinical condition. This condition affects children and often requires numerous invasive surgeries to correct. Minimally invasive external loading of the skull has shown some success in achieving therapeutic effects in a mouse model of this condition, promising a new non-invasive treatment approach. However, our fundamental understanding of the level of deformation that such loading has induced across the sutures, leading to the effects observed is severely limited, yet crucial for its scalability. We carried out a series of multiscale characterisations of the loading effects on normal and craniosynostotic mice, in a series of in vivo and ex vivo studies. This involved developing a custom loading setup as well as software for its control and a novel in situ CT strain estimation approach following the principles of digital volume correlation. Our findings highlight that this treatment may disrupt bone formation across the sutures through plastic deformation of the treated suture. The level of permanent deformations observed across the coronal suture after loading corresponded well with the apparent strain that was estimated. This work provides invaluable insight into the level of mechanical forces that may prevent early fusion of cranial joints during the minimally invasive treatment cycle and will help the clinical translation of the treatment approach to humans.

颅面关节过早融合（即缝合）是主要的临床病症。这种情况会影响儿童，通常需要进行多次侵入性手术才能纠正。微创颅骨外部负载在这种情况的小鼠模型中取得了一些成功的治疗效果，有望成为一种新的非侵入性治疗方法。然而，我们对这种负载在缝合线上引起的变形程度（导致观察到的效果）的基本理解受到严重限制，但这对其可扩展性至关重要。我们在一系列体内和离体研究中对正常小鼠和颅缝早闭小鼠的负载效应进行了一系列多尺度表征。这涉及开发定制加载设置及其控制软件，以及遵循数字体积相关原理的新型原位 CT 应变估计方法。我们的研究结果强调，这种治疗可能会通过处理后的缝合线的塑性变形来破坏缝合线的骨形成。加载后观察到的跨冠状缝的永久变形水平与估计的表观应变非常一致。这项工作为了解机械力的水平提供了宝贵的见解，机械力的水平可能会阻止微创治疗周期中颅骨关节的早期融合，并将有助于将治疗方法应用于人类的临床转化。