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

Abstract

Background Progressive collapsing foot deformity (PCFD) is a complex 3-dimensional (3-D) deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot varus. The first aim of this study was to perform a 3-D analysis of the talus morphology between symptomatic PCFD patients that underwent operative flatfoot correction and controls. The second aim was to investigate if there is an impact of individual talus morphology on the success of operative flatfoot correction. Methods We reviewed all patients that underwent lateral calcaneal lengthening for correction of PCFD between 2008 and 2018 at our clinic. Radiographic flatfoot parameters on preoperative and postoperative radiographs were assessed. Additionally, 3-D surface models of the tali were generated using computed tomography (CT) data. The talus morphology of 44 flatfeet was compared to 3-D models of 50 controls without foot or ankle pain of any kind. Results Groups were comparable regarding demographics. Talus morphology differed significantly between PCFD and controls in multiple aspects. There was a 2.6° increased plantar flexion (22.3° versus 26°; p = 0.02) and medial deviation (31.7° and 33.5°; p = 0.04) of the talar head in relation to the body in PCFD patients compared to controls. Moreover, PCFD were characterized by an increased valgus (difference of 4.6°; p = 0.01) alignment of the subtalar joint. Satisfactory correction was achieved in all cases, with an improvement of the talometatarsal-angle and the talonavicular uncoverage angle of 5.6° ± 9.7 (p = 0.02) and 9.9° ± 16.3 (p = 0.001), respectively. No statistically significant correlation was found between talus morphology and the correction achieved or loss of correction one year postoperatively. Conclusion The different morphological features mentioned above might be contributing or risk factors for progression to PCFD. However, despite the variety of talar morphology, which is different compared to controls, the surgical outcome of calcaneal lengthening osteotomy was not affected. Level of evidence III.

The Foot and Ankle Kinematics of a Simulated Progressive Collapsing Foot Deformity During Stance Phase: A Cadaveric Study

“…Both clinical static studies and in vivo motion capture studies, which have extensively described talonavicular and forefoot abduction in PCFD, support these findings. 5,19,20,24,33,39,44,48 The kinematic data obtained from this study enhance understanding of the talonavicular joint in PCFD. In midstance, the talonavicular joint has relatively less motion.…”

Axial Plane Rotation of the Talus in Progressive Collapsing Foot Deformity: A Weightbearing Computed Tomography Analysis

“…We also directly measured the talar rotation within the mortise (Method 2) because different talar morphologies (body-to-head angles) have been suggested between PCFD patients and controls, although this difference has been reported to be only about 2 degrees. 13 Contrary to previously published methods, 22 we chose to measure the angle between the talus and the LM rather than the medial malleolus because the internal rotation of the talus may cause bone loss and result in changes to the shape of the medial malleolus. Both measures demonstrated internal talar rotation in the PCFD group significantly greater than that of the control group, which is consistent with our hypothesis.…”

Joint coverage analysis in progressive collapsing foot deformity

“…A talar alignment shift also impacts the observed increase in anterior‐medial facet subluxation, as well as reductions in the TN joint coverage 22–24 . The medial shift of the talus results in a pes planus alignment of the calcaneus, which, due to the interconnectivity of the foot, influences the alignment of the cuboid 9,25 . Interestingly, the CC joint alignment does not have an adequate radiographic measure to quantify alignment with respect to other bones within the joint.…”

“…When treating PCFD clinicians aim to preserve as much peritalar joint motion as possible, yet, joint‐sacrificing procedures, such as realignment fusions, are often used to obtain and maintain correction of the deformity in more complex cases 8 . However, a fusion is a permanent loss of range of motion and not an optimal first step for less complex PCFD cases 8,9 . It is important to note that greater complexity of the deformity can be associated with secondary findings such as loss of joint flexibility, subfibular impingement, sinus tarsi impingement, and posterior process fractures of the talus 2,10 .…”