_applied sciences_  
_Article_  
**Three-Dimensional Bone Alignment from Cone-Beam Computed-Tomography Scans in Weight-Bearing and Clinical Outcomes Following the Modified Grice-Green Surgical Procedure for Adult Acquired Flatfoot**  
[PERSON], [PERSON],*2, [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON]  
1 Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; [EMAIL_ADDRESS] (G.S.); [EMAIL_ADDRESS] (M.O.); [EMAIL_ADDRESS] (A.L.); [EMAIL_ADDRESS] (L.P)  
2 Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104, USA  
3 Diagnostic and Interventional Radiology Unit, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; [EMAIL_ADDRESS]  
4 Physical Medicine and Rehabilitation Unit, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; [EMAIL_ADDRESS] (D.P); [EMAIL_ADDRESS] (L.B)  
5 Department of Biomedical and Neuromotor Sciences, University of Bologna, 40127 Bologna, Italy  
* Correspondence: [EMAIL_ADDRESS]  
**Featureued Application: Inclusion of cone-beam computed-tomography scans in weight-bearing, combined with clinical score systems, may lead to more robust pre- and post-operative evaluations of correction surgery following the modified Grice-Green surgical procedure for adult acquired fatfoot, as well as more biomechanically based skeletal investigations of foot alignment.**  
**Abstract: Severe adult-acquired flatfoot deformity is widely addressed surgically via the Grice-Green subtalar arthrodisis. Standard radiographic measurements have been reported, but these are limited to planar views. These complex deformities and the relevant corrections after surgery should be assessed in weight-bearing using 3D analyses now enabled by modern cone-beam CT scans. The present study is aimed at reporting these 3D radiographical foot bone alignments and the clinical results for this surgery. Ten patients were treated with the Grice-Green procedure. This implies inserting an autologous bone graft from the proximal tibial into the extra-articular sinus-tarsi to perform a subtalar arthrodisesis. Before and after surgery, the patients were assessed based on the clinical range-of-motion and Foot-Function and Posture Indexes. Three-dimensional models of the tibia, calcaneus, talus, navicular, and 1 st metatarasus were reconstructed from cone-beam CT scans in a single-leg up-right posture. Relevant longitudinal axes were defined to calculate ten spatial angles. Post-operatively, a significant realignment was observed for seven angles, including corrections lift-up of the talus (on average by 15\({}^{\circ}\)) and subtalar joint (13\({}^{\circ}\) in 3D), as well as the Meary's angle (21\({}^{\circ}\)). Only few correlations were found between traditional clinical and novel 3D radiographical measurements, suggesting the former only limitedly represent the corresponding real skeletal status, and the latter thus offer the physician a more comprehensive evaluation. The present original analysis from modern cone-beam CT scans shows precisely the correction of foot and ankle bone alignments achieved using the Grice-Green surgical procedure, finally in 3D and in weight-bearing. For the first time, traditional clinical and score system evaluations are reported together with bone orientation and joint angles in the three anatomical planes.**  
**Keywords: adult acquired flatfoot; modified Grice-Green surgical procedure; foot clinical outcome; cone-beam computed-tomography; weight-bearing; 3D foot bone alignment**