Analysis of biomechanical stresses caused by hindfoot joint arthrodesis in the treatment of adult acquired flatfoot deformity: A finite element study

Comparison of the Acute Postoperative Complications Between Isolated Talonavicular Versus Talonavicular and Subtalar (Double) Arthrodesis in Flatfoot Deformity

BACKGROUND

Both isolated talonavicular arthrodesis and talonavicular and subtalar (such as double) arthrodesis can be effective treatments for adult-acquired flatfoot deformity (AAFD) with good success rates, but double arthrodesis has become more commonly performed in recent years. The purpose of this study is to evaluate whether isolated talonavicular versus talonavicular and subtalar arthrodesis led to significantly different 30-day postoperative complication rates in patients with AAFD.

METHODS

We performed a retrospective review to identify a large cohort of adult patients with the diagnosis of AAFD or posterior tibial tendon deformity (PTTD) who underwent isolated talonavicular or talonavicular and subtalar arthrodesis between 2006 and 2020 from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). To investigate whether there was a difference in complication rate between the 2 surgical cohorts, we estimated logistic regression models and log-binomial models on each of the outcomes while also adjusting for sex and age.

RESULTS

We found that there was no significant difference in the rate of major complications (P = .567) or readmissions (P = .567) between patients who underwent isolated talonavicular versus talonavicular and subtalar arthrodesis for AAFD. However, there was a significantly higher rate of minor complications in patients who underwent isolated talonavicular arthrodesis when compared with patients who underwent talonavicular and subtalar arthrodesis (P = .009).

CONCLUSION

This study found that there was no increased risk of 30-day postoperative complications or readmissions with talonavicular and subtalar arthrodesis when compared with isolated talonavicular arthrodesis for AAFD. In addition, there was no increased risk of major complications for talonavicular and subtalar arthrodesis when compared with isolated talonavicular arthrodesis, and isolated talonavicular arthrodesis actually carried a higher risk of minor complications for this surgical cohort. This may provide valuable information for surgeons considering surgical treatment for a particular case of AAFD.

LEVEL OF EVIDENCE

Level III.

Ligament Insufficiency with Flatfoot: Spring Ligament and Deltoid Ligament

The objective of this article was to review the deltoid ligament and spring ligament specifically as they pertain to ligament insufficiency and adult-acquired flatfoot deformity. Discussion includes the normal and abnormal biomechanical forces that extend through these ligaments in normal and flatfoot deformity. Current literature related to spring ligament repair as part of the flatfoot deformity reconstruction is also reviewed.

Disease-Specific Finite element Analysis of the Foot and Ankle

Finite-element analysis is a computational modeling technique that can be used to quantify parameters that are difficult or impossible to measure externally in a geometrically complex structure such as the foot and ankle. It has been used to improve our understanding of pathomechanics and to evaluate proposed treatments for several disorders, including progressive collapsing foot deformity, ankle arthritis, syndesmotic injury, ankle fracture, plantar fasciitis, diabetic foot ulceration, hallux valgus, and lesser toe deformities. Parameters calculated from finite-element models have been widely used to make predictions about their biomechanical correlates.

A Critical Biomechanical Evaluation of Foot and Ankle Soft Tissue Repair

The objective of this article is to review the biomechanical stresses that occur during normal physiologic function of lower extremity soft tissue anatomic structures and to use this as a baseline for a critical analysis of the medical literature because it relates to surgical reconstruction following injury. The Achilles tendon, anterior talofibular ligament, plantar plate, and spring ligament are specifically evaluated.

A Review of Finite Element Models of Ligaments in the Foot and Considerations for Practical Application

PURPOSE

Finite element (FE) modeling has been used as a research tool for investigating underlying ligaments biomechanics and orthopedic applications. However, FE models of the ligament in the foot have been developed with various configurations, mainly due to their complex 3D geometry, material properties, and boundary conditions. Therefore, the purpose of this review was to summarize the current state of finite element modeling approaches that have been used in the ?eld of ligament biomechanics, to discuss their applicability to foot ligament modeling in a practical setting, and also to acknowledge current limitations and challenges.

METHODS

A comprehensive literature search was performed. Each article was analyzed in terms of the methods used for: (a) ligament geometry, (b) material property, (c) boundary and loading condition related to its application, and (d) model verification and validation.

RESULTS

Of the reviewed studies, 80% of the studies used simplified representations of ligament geometry, the non-linear mechanical behavior of ligaments was taken into account in only 19.2% of the studies, 33% of included studies did not include any kind of validation of the FE model.

CONCLUSION

Further refinement in the functional modeling of ligaments, the micro-structure level characteristics, nonlinearity, and time-dependent response, may be warranted to ensure the predictive ability of the models.

Biomechanical comparison among five mid/hindfoot arthrodeses procedures in treating flatfoot using a musculoskeletal multibody driven finite element model

BACKGROUND AND OBJECTIVE

Mid/hindfoot arthrodesis could modify the misalignment of adult-acquired flatfoot and attenuate pain. However, the long-term biomechanical effects of these surgical procedures remain unclear, and the quantitative evidence is scarce. Therefore, we aimed to investigate and quantify the influences of five mid/hindfoot arthrodeses on the internal foot biomechanics during walking stance.

METHODS

A young participant with flexible flatfoot was recruited for this study. We reconstructed a subject-specific musculoskeletal multibody driven-finite element (FE) foot model based on the foot magnetic resonance imaging. The severe flatfoot model was developed from the flexible flatfoot through the attenuation of ligaments and the unloading of the posterior tibial muscle. The five mid/hindfoot arthrodeses simulations (subtalar, talonavicular, calcaneocuboid, double, and triple arthrodeses) and a control condition (no arthrodesis) were performed simultaneously in the detailed foot multibody dynamics model and FE model. Muscle forces calculated by a detailed multi-segment foot model and ground reaction force were used to drive the foot FE model. The internal foot loadings were compared among control and these arthrodeses conditions at the first and second vertical ground reaction force (VGRF) peak and VGRF valley instants.

RESULTS

The results indicated that the navicular heights in double and triple arthrodeses were higher than other surgical procedures, while the subtalar arthrodesis had the smallest values. Five mid/hindfoot arthrodeses reduced the peak plantar fascia stress compared to control. However, double and triple arthrodeses increased the peak medial cuneo-navicular joint contact pressures and peak foot pressures as well as the metatarsal bones stresses.

CONCLUSION

Although mid/hindfoot arthrodesis generally reduced the collapse of medial longitudinal arch and plantar fascia loading during the stance phase, the increased loading in the adjacent unfused joint and metatarsal bones for double and triple arthrodeses should be noted. These findings could account for some symptoms experienced by flatfoot patients after surgery, which may facilitate the optimization of surgical protocols.

Is Advanced Imaging a Must in the Assessment of Progressive Collapsing Foot Deformity?

Advanced imaging modalities have, in very recent years, enabled a considerable leap in understanding progressive collapsing foot deformity, evolving from a simple confirmation of clinical diagnostic using basic measurements to minute understanding of soft tissue and bone involvements. MRI and weight-bearing cone-beam computed tomography are enabling the development of new 3-dimensional measurement modalities. The identification of key articular and joint markers of advanced collapse will allow surgeons to better indicate treatments and assess chances of success with conservative therapies and less invasive surgical procedures, with the hope of improving patient outcomes.

Analysis of the main soft tissue stress associated with flexible flatfoot deformity: a finite element study

A better understanding of soft tissue stress and its role in supporting the medial longitudinal arch in flexible flatfoot could help to guide the clinical treatment. In this study, a 3-Dimensional finite element (FE) foot model was reconstructed to measure the stress of the soft tissue, and its variation in different scenarios related to flexible flatfoot. All bones, cartilages, ligaments and related tendons around the ankle, and fat pad were included in the finite element model. The equivalent stress on the articular surface of the joints in the medial longitudinal arch and the maximum principal stress of the ligaments around the ankle were obtained. The results show that the plantar fascia (PF) is the main tissue in maintaining the medial longitudinal arch. The equivalent stress of all the joints in the medial longitudinal arch increases when the PF attenuation and the talonavicular joint increases, while other joints decreases when all the three tissue attenuation. Moreover, the maximum principal stress variation of calcaneofibular ligament is largest when the PF attenuation and the tibionavicular ligament and posterior tibiotalar ligament are largest when the posterior tibial tendon (PTT) attenuation. The maximum principal stress variation of tibionavicular ligament and posterior tibiotalar ligament are even larger when all the three tissue attenuation. These findings support that the PF is the main factor in maintaining the medial longitudinal arch. The medial longitudinal arch collapse mainly affects the talonavicular joint and the calcaneofibular ligament, the tibionavicular ligament and the posterior tibiotalar ligament. This approach could help to improve the understanding of adult-acquired flatfoot deformity (AAFD).