The reliability and validity of radiographic measurements for determining the three-dimensional position of the talus in varus and valgus osteoarthritic ankles

Abstract

ObjectiveTo assess the most accurate radiographic method to determine talar three-dimensional position in varus and valgus osteoarthritic ankles, we evaluated the reliability and validity of different radiographic measurements.Materials and methodsNine radiographic measurements were performed blindly on weight-bearing mortise, sagittal, and horizontal radiographs of 33 varus and 33 valgus feet (63 patients). Intra- and interobserver reliability was determined with the intraclass coefficient (ICC). Discriminant validity of measurements between varus and valgus feet was assessed with effect size (ES). Convergent validity (Pearson’s r) was evaluated by correlating measurements to the dichotomized varus and valgus groups. Obtained measurements in both groups were finally compared with each other and with 30 control feet.ResultsReliability was excellent (ICC > 0.80) in all but two measurements. Whereas frontal plane validity was excellent (ES and r > 0.80), horizontal and sagittal measurements showed poor to moderate validity (ES and r between 0.00 and 0.60). Four measurements were significantly different among all groups (p < 0.05). Talar positional tendency was found towards dorsiflexion or endorotation in the varus group and towards plantarflexion or exorotation in the valgus group. The frontal tibiotalar surface angle, sagittal talocalcaneal inclination angle, and horizontal talometatarsal I angle showed the best reliability, validity, and difference among the groups.ConclusionThe frontal tibiotalar surface angle, sagittal talocalcaneal inclination angle, and horizontal talometatarsal I angle accurately determine talar three-dimensional radiographic position in weight-bearing varus and valgus osteoarthritic ankles. Careful radiographic evaluation is important, as these deformities affect talar position in all three planes.

The effect of posture on the osseous relations in the foot

“…The mean of the foot angles in the present study were between the values reported in previous studies with radiographs [8,[31][32][33][34][35][36] and skin markers during midstance of gait [37]. The variation across subjects (indicated by the standard deviation in Table 2) was with 14.38 slightly higher than the approximately 108 reported in the literature [8,[31][32][33]35,37,38].…”

“…The variation across subjects (indicated by the standard deviation in Table 2) was with 14.38 slightly higher than the approximately 108 reported in the literature [8,[31][32][33]35,37,38]. The importance of the posture on foot angles can be indicated by the effect of the postures in relation to the variation of the foot angles across subjects (between subject standard deviation).…”

“…For example, the effect of posture in flexible feet might have been larger than in more rigid feet. Furthermore, the foot angles in natural position show large differences between subjects [14,32,38]. As a consequence, the degree of impact of postures on foot angles can differ between the subjects due to their foot shape.…”

Effect of Supramalleolar Osteotomy and Total Ankle Replacement on Talar Position in the Varus Osteoarthritic Ankle

“…5,14,27 The sagittal position of the talus was determined on the lateral view measuring the talocalcaneal inclination angle (TCI) and the tibial lateral surface angle (TLS). 14,23 The rotation of the talus was assessed on the AP foot view with the talometatarsal 1 angle (TMT1), endorotation of the talus related to the first metatarsal was defined as a positive value. 23 The hindfoot alignment was assessed measuring the calcaneus offset on the Saltzman view.…”

“…14,23 The rotation of the talus was assessed on the AP foot view with the talometatarsal 1 angle (TMT1), endorotation of the talus related to the first metatarsal was defined as a positive value. 23 The hindfoot alignment was assessed measuring the calcaneus offset on the Saltzman view. 25 We published in a previous study the reliability and validity of these angles in a normal cohort (NC).…”