Systematic Quantification of Stabilizing Effects of Subtalar Joint Soft-Tissue Constraints in a Novel Cadaveric Model

Patients with mechanic ankle instability experience increased tibiotalar and subtalar joint laxity. However, in vivo joint kinematics in functional ankle instability (FAI) patients and lateral ankle sprain (LAS) copers, especially during dynamic activities, are poorly understood. Ten FAI patients, 10 LAS copers, and 10 healthy controls were included in this study. A dual fluoroscopic imaging system was used to analyze the tibiotalar and subtalar joint kinematics during stair descent. Five key poses of stair descent were analyzed. Kinematic data from six degrees of freedom were calculated utilizing a solid modeling software. The range of motion and joint positions in each degree of freedom were compared among the three groups. The tibiotalar joints of FAI patients and LAS copers were significantly more inverted than those of healthy controls during the foot strike (p = 0.016, η p 2 = 0.264). The subtalar joints of FAI patients were significantly more anteriorly translated (pose 2, p = 0.003, η p 2 = 0.352; pose 3, p < 0.001, η p 2 = 0.454; pose 4, p = 0.004, η p 2 = 0.334), inverted (pose 4, p = 0.027, η p 2 = 0.234; pose 5, p = 0.034, η p 2 = 0.221), and externally rotated (pose 4, p = 0.037, η p 2 = 0.217; pose 5; p = 0.004, η p 2 = 0.331) than those of healthy controls during the mid-stance and the heel off. The FAI patients showed excessive tibiotalar inversion and subtalar joint hypermobility during stair descent. Meanwhile, the LAS copers maintained subtalar joint stability, and only showed excessive tibiotalar inversion in foot strike. These data provide insight into the mechanisms behind the development of FAI after initial LAS.

Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

In Vivo Kinematics of Functional Ankle Instability Patients and Lateral Ankle Sprain Copers During Stair Descent

Cao

Wang

et al. 2019

“…2 Two ligaments are the primary stabilizers of the subtalar joint: the interosseous talo-calcaneal ligament (ITCL) and the calcaneo-fibular ligament (CFL). [6][7][8][9] Other ligaments providing subtalar joint stability include the cervical ligament, lateral talo-calcaneal ligament, and deltoid ligament. [6][7][8]10,11 Recent cadaver studies showed that the CFL is potentially the most important stabilizer of the subtalar joint when subjected to inversion and external rotation stress.…”

mentioning

confidence: 99%

“…[6][7][8][9] Other ligaments providing subtalar joint stability include the cervical ligament, lateral talo-calcaneal ligament, and deltoid ligament. [6][7][8]10,11 Recent cadaver studies showed that the CFL is potentially the most important stabilizer of the subtalar joint when subjected to inversion and external rotation stress. 7,8 As the CFL crosses both the ankle and subtalar joint, the stability of both joints is affected after injury.…”

mentioning

confidence: 99%

“…[6][7][8]10,11 Recent cadaver studies showed that the CFL is potentially the most important stabilizer of the subtalar joint when subjected to inversion and external rotation stress. 7,8 As the CFL crosses both the ankle and subtalar joint, the stability of both joints is affected after injury. In contrast, the ITCL only provides stability to the subtalar joint.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Can Weightbearing Computed Tomography Scans Be Used to Diagnose Subtalar Joint Instability? A Cadaver Study

Krähenbühl

Burssens

Davidson

et al. 2019

Chronic hindfoot instability is a frequent problem that includes the ankle and/or the subtalar joint. While ankle joint instability can be diagnosed clinically, accurate assessment of the subtalar joint remains elusive. This study's purpose was to assess the ability of weightbearing computed tomography (CT) scans to detect subtalar joint instability. Seven pairs of fresh frozen male cadavers (tibial plateau to toe‐tip) were tested. A radiolucent frame held specimens in a plantigrade position while non‐weightbearing and weightbearing CT scans (with and without torque application) were taken. First, intact ankles (Native) were scanned. Second, one specimen from each pair underwent interosseous talo‐calcaneal ligament (ITCL) transection, while the contralateral underwent calcaneo‐fibular ligament (CFL) transection. Third, the remaining intact ITCL or CFL was transected. Finally, the deltoid ligament was transected in all ankles. Eight radiographic measurements were performed to assess the congruency of the subtalar joint on digitally reconstructed radiographs and single CT images. Axial loading did not impact most measurements, whereas torque did impact most measurements. Radiographic measurements performed at the subtalar joint level were more reliable and better predictors for subtalar joint instability compared with measurements performed at the ankle joint level. While torque application is crucial to identify subtalar joint instability, axial load application should be avoided. Measurements to assess the subtalar joint stability should primarily be performed at the subtalar joint level rather than at the ankle joint level when using weightbearing CT scans. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2457–2465, 2019

Interaction of loading and ligament injuries in subtalar joint instability quantified by 3D weightbearing computed tomography

Burssens

Krähenbühl

Lenz

et al. 2021

Despite decades of research since its first description, subtalar joint instability remains a diagnostic enigma within the concept of hindfoot instability. This could be attributed to current imaging techniques, which are impeded by two‐dimensional measurements. Therefore, we used weightbearing computed tomography imaging to quantify three‐dimensional displacement associated with subtalar joint instability. Three‐dimensional models were generated in seven paired cadaver specimens to compute talocalcaneal displacement after different patterns of axial load (85 kg) combined with torque in internal and external rotation (10 Nm). Sequential imaging was repeated in the subtalar joint containing intact ligaments to determine reference displacement. Afterward, the interosseus talocalcaneal ligament (ITCL) or calcaneofibular ligament (CFL) was sectioned, then the ITCL with CFL and after the ITCL, CFL with the deltoid ligament (DL). The highest translation could be detected in the dorsal direction and the highest rotation occurred in the internal direction when external torque was applied to the foot without load. These displacements differed significantly from the condition containing intact ligaments, with a mean difference of 1.6 mm (95% CI, 1.3 to 1.9) for dorsal translation and a mean of 12.4° (95% CI, 10.1 to 14.8) for internal rotation. Clinical relevance: Our study provides a novel and noninvasive analysis to quantify subtalar joint instability based on three‐dimensional WBCT imaging. This approach overcomes former studies using trans‐osseous fixation to determine three‐dimensional subtalar joint displacement and implements an imaging device and software modalities that are readily available. Based on our findings, we recommend applying torque in external rotation to the foot to optimize the detection of subtalar joint instability.