Talar neck angle correlates with tibial torsion—Guidance for 3D and 2D measurements in total ankle replacement

Abstract

Axial plane alignment of the talar component in total ankle arthroplasty is poorly understood and remains a major issue, especially since malpositioning results in increased peak pressure and rotational torque. Further profound knowledge regarding individual anatomy of the talus and its relation to proximal and distal osseous structures is therefore needed. Therefore, three-dimensional (3D) surface models of 50 lower extremities were generated using computed tomography data of patients without ankle osteoarthritis. The talus neck torsion was measured using a novel 3D measurement method. Then, tibial torsion and subtalar joint axis orientation were measured and correlated to the talus neck torsion. Moreover, a 2D measurement method of the talus neck torsion was developed. A statistically significant correlation was found between external tibia torsion and medial talus neck torsion, as well as talus neck axis and subtalar joint axis in the transversal and frontal plane. The novel defined 3D measurement methods indicated excellent inter-rater and intra-rater reliability. The 2D measurement method of the talus neck torsion was in good agreement with the 3D method. The results showed that the rotational profiles of the tibia, talus, and adjacent joints are interconnected, which should be considered in total ankle replacement (TAR). Clinical relevance: This study improves the overall understanding of the talar anatomy, as well as its relationship to adjacent osseous structures. The novel 2D measurement method of the talus neck torsion might improve talar component positioning in the axial plane corresponding to the patient's individual anatomy, and therefore improve the survival rate of TAR. K E Y W O R D S extramedullary referencing, talar neck torsion, total ankle replacement 1 | INTRODUCTION Osteoarthritis of the ankle is an increasing issue with about 1% of the adult population affected. 1 For end-stage osteoarthritis, total ankle replacement (TAR) represents an evolving method of treatment. The failure rates of TAR, however, are more than twice as high as the rates after total hip and knee replacements. 2 Reasons might be an insufficient consideration of the anatomy as well as the limited predictability due to the use of conventional radiographs for planning of the prosthesis. 3 In coronal and sagittal planes, component positioning is ensured with preoperative weight-bearing radiographs and intraoperative extramedullary

WITHDRAWN: Establishment of a Finite Element Model and Biomechanical Analysis of Different Fixation Methods for Total Talar Prosthesis Replacement

“…Its anatomical structure is complex, and it is the mechanical point of rotation between the lower limb and foot. Stress is concentrated in this area, and the mechanical properties are particularly important [1][2][3]. Collapsible talus necrosis severely affects individuals' ability to stand and walk, with a disability rate of 100%.…”

Tibial torsion and pressures in the feet during walking: Implications for patterns of metatarsal robusticity

“…The high talar neck angle of the Dmanisi specimen (26°, in the upper end of the modern human range) suggests a very medially oriented foot and potentially a negative FPA when paired with just 1° of tibial torsion (Bleck & Minaire, 1983; Lordkipanidze et al, 2007; Pontzer et al, 2010). It is not clear whether talar neck angle has a positive or negative relationship with tibial torsion in modern humans (Ciufo et al, 2022; Flury et al, 2021). Our data could not test the possible interactions between tibial torsion and talar neck angle, but support the idea that additional static or dynamic structures may have a greater influence on neutral foot position than tibial torsion does.…”

“…A high talar neck angle indicates a more medial inclination of the head of the talus relative to the trochlea, is associated with a lower FPA in humans, and is cited as a common cause of in‐toeing (Bleck & Minaire, 1983; Ciufo et al, 2022; Flury et al, 2021; Wallace et al, 2008). The high talar neck angle of the Dmanisi specimen (26°, in the upper end of the modern human range) suggests a very medially oriented foot and potentially a negative FPA when paired with just 1° of tibial torsion (Bleck & Minaire, 1983; Lordkipanidze et al, 2007; Pontzer et al, 2010).…”

Talus morphology differs between flatfeet and controls, but its variety has no influence on extent of surgical deformity correction

“…In addition, a valgus subtalar joint axis might likely be another contributing or perhaps even primary risk factor for the progression of valgus angulation of the hindfoot [7]. This led to the hypothesis, that further anatomical/morphological characteristics of the talar bone might exist in PCFD, which have been insufficiently investigated so far [27].…”

“…A sphere was created and manually adjusted to best fit the talonavicular articular surface (talus head) by the first author (Fig. 1c) [25,27]. The talus neck axis was defined as the axis between the centre of mass of the superior articular surface of the talus and the centre of the talus head (Fig.…”