Effects of extraosseous talotarsal stabilization on the biomechanics of flexible flatfoot subtalar joints in children: a finite element study

<p class="abstract"><strong>Background:</strong> Objective of the study was to generate an experimental foundation for the clinical application of extraosseous talotarsal stabilization (EOTTS) in treatment of flexible flatfeet in children by investigating the biomechanical characteristics of flexible flatfoot and the effects of EOTTS on hindfoot biomechanics.</p><p class="abstract"><strong>Methods:</strong> Three-dimensional finite element models of the foot and ankle complex were generated from computer tomography images of a volunteer’s left foot in three states: normal, flexible flatfoot, and post-EOTTS. After validation by X-ray, simulated loads were applied to the three models in a neutral position with both feet standing.</p><p class="abstract"><strong>Results:</strong> In the flexible flatfoot model, the contact stress on the subtalar joint increased and contact areas decreased, resulting in abnormal stress distribution compared to the normal model. However, following treatment of the foot with EOTTS, these parameters returned to close to normal. Subtalar joint instability leads to a flexible flat foot. Based on this study, it is proposed that EOTTS can restore the normal function of the subtalar joint in and is an effective treatment for flexible flatfoot in children. We and many clinical data studies provide evidence for sinus tarsi implants in pediatric patients. It is showed that the formation of flexible flatfoot is induced by subtalar joint instability.</p><p class="abstract"><strong>Conclusions:</strong> Because of the EOTTS provides the best biomechanical solution to subtalar joint instability, the EOTTS became an effective form for subtalar joint instability treatment.</p>

Arthroscopic treatment for posteromedial talar process fracture (Cedell fracture): a case report

Fracture of the posteromedial talar process (Cedell fracture) is a rare injury and is easily misdiagnosed as a simple ankle sprain. Suspicion should be heightened if specific mechanisms of injury are present, and, in these cases, a CT scan should be performed. Significant ankle pain and disability can result if these injuries are not identified and treated properly. Few cases have been described in the literature, and the efficacy of surgical techniques and approaches for fractures of the posterior talar process remains controversial. We report a 56-year-old man with an acute posteromedial talar fracture treated arthroscopically. This approach provides good access to the posterior ankle compartment, subtalar joint, and extraarticular structures, which may allow fracture reduction and fixation under arthroscopic visualization. Level of Evidence V; Therapeutic Studies; Expert Opinion.

A Modified Extra-articular Lateral Column Lengthening Procedure for Adult Acquired Flatfoot Deformity

Background: Lateral column lengthening (LCL), originally described by Evans, is an established procedure to correct stage II adult acquired flatfoot deformity (AAFD). However, the relative position between the facets is violated, and other problems may include nonunion, malunion, and calcaneocuboid (CC) joint subluxation. Herein, we report a modified extra-articular technique of LCL with hockey-stick osteotomy, which preserves the subtalar joint as a whole, increases bony apposition to enhance healing ability, and preserves the insertion of the calcaneofibular ligament to stabilize the posterior fragment to promote adduction of the forefoot. Methods: We retrospectively recruited 24 patients (26 feet) with stage II AAFD who underwent extra-articular LCL. The mean age was 55.7 ± 15.7 years, and the mean follow-up period was 33.4 ± 12.1 months. Associated procedures of spring ligament repair/reconstruction and posterior tibial tendon plication or flexor digitorum longus transfer were routinely performed and may also include a Cotton osteotomy, heel cord lengthening, or hallux valgus correction. Clinical and radiographic outcomes at the final follow-up were compared with the preoperative assessments. Results: All patients achieved calcaneus union within 3 months of operation. The VAS pain score improved from 5.3 ± 0.75 preoperatively to 1.2 ± 0.79 at the final follow-up ( P < .001), and the AOFAS Ankle-Hindfoot Scale from 63.5 ± 8.5 to 85.8 ± 4.8 points ( P < .001). The radiographic measurements significantly improved in terms of the preoperative vs final angles of 8.9 ± 5.3 vs 15.2 ± 3.6 degrees for calcaneal pitch ( P < .001), 20.5 ± 9.2 vs 4.9 ± 4.8 degrees for Meary angle ( P < .001), 46.5 ± 5.2 vs 41.9 ± 3.2 degrees for lateral talocalcaneal angle ( P < .001), 23.9 ± 8.5 vs 3.9 ± 3.1 degrees for talonavicular coverage angle ( P < .001), and 18.2 ± 9.2 vs 7.3 ± 5.0 degrees for talus-first metatarsal angle ( P = .002). The CC joint subluxation percentage was 7.0% ± 5.4% preoperatively compared with 8.5% ± 2.4% at the final follow-up ( P = .101). No case showed progression of CC joint arthritis or CC joint subluxation (>15% CC joint subluxation percentage). One case showed transient sural nerve territory paresthesia, and 1 had pin tract infection. Three cases had lateral foot pain, which could be relieved by custom insoles. Conclusion: Modified extra-articular LCL as part of AAFD correction is a feasible alternative technique without subtalar joint invasion and may be associated with less CC joint subluxation compared with the Evans osteotomy. Level of Evidence: Level IV, retrospective case series.

Hindfoot motion analysis by subtalar compensation and ankle osteoarthritis stage using a multi-segment foot model

Background The biomechanics of the hindfoot in ankle osteoarthritis (OA) are not yet fully understood. Here we aimed to identify hindfoot motion in a gait analysis using a multi-segment foot model (MFM) according to ankle OA stage or hindfoot alignment by the presence of subtalar compensation. Methods We retrospectively reviewed the medical records, simple radiographs, and gait MFM data of 54 ankles admitted to our hospital for the treatment of advanced ankle OA. Spatiotemporal gait parameters and three-dimensional motions of the hindfoot segment were analyzed according to sex, age, body mass index, Takakura classification, and presence of subtalar compensation. Results No spatiotemporal gait parameters differed significantly according to the presence of subtalar compensation or ankle OA stage. Only normalized step width differed significantly (P = .028). Average hindfoot motion (decompensation versus compensation) did not differ significantly between the sagittal and transverse planes. Graphing of the coronal movement of the hindfoot revealed collapsed curves in both groups that differed significantly. Compared with Takakura stages 3a, 3b, and 4, cases of more advanced stage 3b had a smaller sagittal range of motion than those of stage 3a (P = .028). Coronal movement of the hindfoot in cases of Takakura stage 3a/3b/4 showed a relatively flat pattern. Conclusions The spatiotemporal parameters were not affected by the alignment state of the heel resulting from subtalar compensation. The sagittal range of hindfoot motion decreased in patients with advanced ankle OA. Once disrupted, the coronal movement of the subtalar joint in ankle OA did not change regardless of ankle OA stage or hindfoot compensation state.

First metatarsal elevation after subtalar arthroeresis in children with flatfeet

BACKGROUND: Arthroereisis of the subtalar joint is a common surgical option for children with flat feet. Along with all the advantages of arthroereisis of the subtalar joint, the indications for surgery, the optimal age for surgical treatment, as well as secondary deformities of the forefoot that occur after treatment are debatable. AIM: The aim of this study was to analyze the frequency and degree of I metatarsal elevation after arthroereisis of the subtalar joint in children. MATERIALS AND METHODS: The study group included 106 patients / 202 feet who were treated at the H. Turner Pediatric Orthopedic Institute for the period from 2015 to 2019. The average age was 11 years (8; 13). Arthroereisis of the subtalar joint was performed in two variants: arthroereisis with a locking screw in the calcaneus 44 patients / 83 feet and arthroereisis with a locking screw in the talus 62 patients / 119 feet. An analysis was made of the incidence of I metatarsal elevation after arthroereisis of the subtalar joint. The relationship between the degree of elevation of the first metatarsal bone and the main clinical and radiological characteristics of the feet at different times after surgical treatment was analyzed. RESULTS: The frequency of elevation of the I metatarsal bone with the use of a calcaneal locking screw was 20.7%, and with the use of a talar locking screw, the frequency is 51.6%. Clinical manifestations of elevation of the I metatarsal bone took place when the amount of elevation was more than 65% of the size of the head of the I metatarsal bone. At a period of 23 years after the operation, elevation of the I metatarsal bone were noted in 15.9%. A statistically significant correlation (Spearman coefficient) was noted between the degree of elevation of the I metatarsal bone and the following parameters: anteroposterior Meary angle (0.360), lateral Kite angle (0.367), lateral Meary angle (0.378), foot arch angle (0.344), tibio-talar angle (0.351), Friedlands index (0.402). CONCLUSIONS: Incidence of the first metatarsal bone elevation reaches 51% of the in patients in the immediate follow-up period after performing arthroereisis of the subtalar joint. Elevation of the first metatarsal bone developed dorsal bunion with an elevation value of more than 65%. The degree of elevation of the first metatarsal bone has a positive correlation with the degree of planovalgus deformity correction. Elevation of the first metatarsal bone tends to decrease up to 15% in the long-term follow-up after surgical treatment.