Influence of ankle joint position on angles and distances of the ankle mortise using intraoperative cone beam CT: A cadaveric study

Abstract

Background The precise anatomical reduction of the ankle mortise is crucial for the clinical outcome in unstable syndesmotic injuries. Intraoperative cone beam computed tomography (CT), in addition to two-dimensional fluoroscopy, provides detailed information about the reduction and implant placement. The aim of this study was to analyze the influence of the joint position on the fibula position in the incisural notch and to determine the inter- and intraindividual anatomical differences in the intact ankle joints. Methods A total of 20 fresh-frozen lower legs disarticulated in the knee joint of 10 individuals were included. The measurements were performed using a cone beam CT. The distances and angles were measured in the standard imaging planes. The mean values of distances and angles were compared during the different joint positions: 10° dorsiflexion, 0° neutral position and 20° plantar flexion. Results The influence of the joint position was on average as follows: The anterior tibiofibular distance was 3.68 mm in 10° dorsiflexion, 3.66 mm (0° neutral position) and 3.59 mm (20° plantar flexion). The posterior tibiofibular distance measured 7.82mm, 7.76mm and 7.82mm. The rotation of the fibula measured ten millimeters proximal the joint line was 1.2°, 1.3° and 1.05°. The fibular rotation determined 4mm was 9.3°, 9.4° and 9.4°. On average, the following intraindividual variations were observed: superior tibiotalar clear space of 0.27mm and 0.15mm medial; and anterior tibiofibular distance of 0.42mm, 0.38mm posterior and 0.24mm in the incisural notch. The proximal angle of the fibular rotation was 0.2° and distal 0.4°. The interindividual variations of the angles and distances exceeded the intraindividual values partly by 3 to 4 fold. Conclusions Within the scope of this study neither the tibiofibular distance, nor the tibiofibular angle changed significantly through the different joint positions. The intraindividual differences were little while the interindividual variations of the parameters were distinctive.

Computer-assisted contralateral side comparison of the ankle joint using flat panel technology

“…Mirroring can only approximate the reality because it assumes that left and right ankles are truly symmetrical. Studies showed that the intra-individual variability is significantly lower than the inter-individual variability [ 5 ]. The input data consists of left and right ankles to generalize towards intra-individual variability eventually caused by biomechanical attrition.…”

“…Reduction refers to the re-alignment of the dislocated bones whereas fixation refers to the attachment of metal implants to fixate the bones. Anatomical reduction is essential and incorrect reduction (malreduction) may cause instability and chondral degeneration leading to premature osteoarthritis [ 5 ]. Intra-operative imaging allows monitoring of the reduction result and implant positioning during all phases of an intervention.…”

Intraoperative three-dimensional imaging in ankle syndesmotic reduction

“…The position of the foot, according to the studies by Levack and Vetter, has no relevant influence on the tibiofibular distance nor on the tibiofibular angle. Therefore, the intraoperative scan can be performed in any position of the ankle and foot [21,22].…”

Intraoperative three-dimensional imaging in ankle syndesmotic reduction.

“…The position of the foot, according to the studies by Levack and Vetter, has no relevant in uence on the tibio bular distance nor on the tibio bular angle. Therefore, the intraoperative scan can be performed in any position of the ankle and foot [21,22].…”