Flatfoot Deformity Due to Isolated Spring Ligament Injury

Biomechanical evaluation of the spring ligament and the posterior tibial tendon by shear-waves elastography: validation of a reliable and reproducible measurement protocol

PURPOSE

The anatomy of the spring ligament complex, as well as its pathology, is not well known in daily clinical practice. The purpose of this study was to evaluate the shear-wave elastography properties of the spring ligament and the posterior tibial tendon in healthy adults, and to assess the reliability and reproducibility of these measurements.

METHODS

Shear-wave elastography was used to evaluate both ankles in 20 healthy patients (10 females/10 males) resting on a hinge support with their ankles in neutral, valgus 20° and varus 30° positions. The stiffness of the spring ligament and posterior tibial tendon was assessed by measuring the speed of shear wave propagation through each structure.

RESULTS

Posterior tibial tendon and spring ligament reach a maximum estimated stiffness in valgus 20° position (7.43 m/s vs 5.73 m/s, respectively). Flat feet were associated with greater spring ligament stiffness in the 20° valgus position (p = 0.01), but not for the posterior tibial tendon (p = 0.71). The physiologic weightbearing hindfoot attitude had no impact on the stiffness of the posterior tibial tendon or the spring ligament, regardless of the analysis position. Intra- and inter-observer agreements were all excellent for spring ligament stiffness, regardless of ankle position, and were good or excellent for posterior tibial tendon.

CONCLUSIONS

This study describes a protocol to assess the stiffness of tibialis posterior and the spring ligament by shear-wave elastography, which is reliable, reproducible, and defines a corridor of normality. Further studies should be conducted to define the role of elastography for diagnosis/ evaluation of pathology, follow-up, or surgical strategies.

Unique shape variations of hind and midfoot bones in flatfoot subjects-A statistical shape modeling approach

Flatfoot deformity is a prevalent hind- and midfoot disorder. Given its complexity, single-plane radiological measurements omit case-specific joint interaction and bone shape variations. Three-dimensional medical imaging assessment using statistical shape models provides a complete approach in characterizing bone shape variations unique to flatfoot condition. This study used statistical shape models to define specific bone shape variations of the subtalar, talonavicular, and calcaneocuboid joints that characterize flatfoot deformity, that differentiate them from healthy controls. Bones of the aforementioned joints were segmented from computed tomography scans of 40 feet. The three-dimensional hindfoot alignment angle categorized the population into 18 flatfoot subjects (≥7° valgus) and 22 controls. Statistical shape models for each joint were defined using the entire study cohort. For each joint, an average weighted shape parameter was calculated for each mode of variation, and then compared between flatfoot and controls. Significance was set at p < 0.05, with values between 0.05 ≤ p < 0.1 considered trending towards significance. The flatfoot population showed a more adducted talar head, inferiorly inclined talar neck, and posteriorly orientated medial subtalar articulation compare to controls, coupled with more navicular eversion, shallower navicular cup, and more prominent navicular tuberosity. The calcaneocuboid joint presented trends of a more adducted calcaneus, more abducted cuboid, narrower calcaneal roof, and less prominent cuboid beak compared to controls. Statistical shape model analysis identified unique shape variations which may enhance understanding and computer-aided models of the intricacies of flatfoot, leading to better diagnosis and, ultimately, surgical treatment.

Spring Ligament Reconstruction for Progressive Collapsing Foot Deformity: Contemporary Review

The spring ligament is one of the main stabilizers of the medial arch of the foot and the primary static supporter of the talonavicular joint. Attenuation or rupture of this ligament is thought to play a central role in the pathophysiology of progressive collapsing foot deformity. Traditional correction of flexible flatfoot consists of posterior tibial tendon augmentation along with various osteotomies or hindfoot fusions. Repair or reconstruction of the spring ligament has not been as widely pursued. In recent years, newer techniques have been explored and may improve outcomes of traditional procedures, or possibly entirely replace some osteotomies. Combined spring-deltoid ligament reconstruction is also gaining traction as a viable technique, particularly as the ankle begins to deform into valgus. This review summarizes the variety of nonanatomic and anatomic reconstruction techniques that have been described, including autologous tendon transfers, allografts, and synthetic augmentation. Although many have only been characterized in biomechanical cadaver studies, this article reviews preliminary clinical studies that have shown promising results. There is a need for more high-quality studies evaluating the clinical, radiographic, and patient-reported outcomes following spring ligament reconstruction.

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.

The Potential of Endoscopic Spring Ligament Repair in Flatfoot Reconstruction

BACKGROUND

Spring ligament fulfills 2 main important functions: one, supporting the head of the talus and stabilizing the talonavicular joint, and the other, maintaining the longitudinal arch by acting as a static support. In this preliminary report, we describe an endoscopic repair for spring ligament injuries with modified portals.

METHODS

We performed a retrospective case series study from February 2019 to January 2022. Posterior tibial tendon and/or associated bone deformities were assessed at the same surgical procedure. All patients were ≥18 years old and they had more than 6 months of follow-up. The procedure was performed in 11 patients. Mean age was 46 years (range 18-63). Ten had concomitant bony realignment surgery, and 8 had posterior tibial tendon surgery.

RESULTS

In all patients, endoscopic spring ligament repair could be technically done. The modified portals were used in all procedures as described in the surgical technique. Three patients had a superficial lesion, 1 had a rupture <5 mm, 7 had a rupture >5 mm but not a complete rupture through the entire spring ligament. Most of the patients had good clinical results from the surgery that included endoscopic spring ligament debridement and/or repair at 2 years follow up.

CONCLUSION

In this small series we found that endoscopy may be an effective technique to diagnose and treat incomplete spring ligament injuries.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Seguridad de los portales para la reparación endoscópica del ligamento calcaneonavicular: estudio cadavérico

Introducción: La lesión del ligamento calcaneonavicular ha sido descrita como una de las causas de la deformidad en el pie plano del adulto. El objetivo de este artículo es describir portales modificados para el diagnóstico y la reparación endoscópica de las lesiones del fascículo superomedial del ligamento calcaneonavicular y evaluar la seguridad de los portales utilizados. Materiales y Métodos: Se llevó a cabo un estudio cadavérico con seis preparados reproduciendo una lesión del fascículo superomedial del ligamento calcaneonavicular con una punta de corte de radiofrecuencia y la posterior reparación endoscópica. Se crearon dos portales modificados para el abordaje. Luego se procedió a la disección anatómica para evaluar la seguridad de los portales en relación con las estructuras anatómicas. El primer portal se realiza inmediatamente proximal a una línea trazada desde la punta del maléolo medial dirigida al centro del talón, el segundo portal se emplaza 0,5 cm proximal a la inserción del tendón tibial posterior en el escafoides por transiluminación. Si es necesario, se coloca un portal accesorio inmediatamente dorsal al tendón tibial posterior a mitad de camino entre los dos portales antes descritos. Resultados: En todos los casos, fue posible la reparación del ligamento con el procedimiento endoscópico. En la disección anatómica de los portales, se observó una distancia promedio a las estructuras vasculonerviosas de 11,83 mm del portal proximal y de 9,66 mm del portal distal. Conclusión: Los portales modificados son seguros y permiten la visualización directa del haz superomedial del ligamento calcaneonavicular y su reparación endoscópica.

Clinical Outcomes of Fusion in Type II Accessory Naviculars With or Without Asymptomatic Flatfeet

BACKGROUND

Few studies have reported the clinical outcomes of fusion surgeries for type II accessory naviculars. Whether the combination of accessory naviculars and asymptomatic flatfoot will result in worse outcomes in accessory navicular surgeries remains to be elucidated. Our study aims to report the clinical outcomes of fusion for type II accessory naviculars and make a subgroup comparison among accessory navicular patients with or without asymptomatic flatfeet.

METHODS

From May 2017 to June 2021, all painful type II accessory naviculars with or without asymptomatic flatfeet in our inpatient center were reviewed, and those who only underwent fusion surgeries were included in the retrospective study. Visual analog scale (VAS) scores, American Orthopaedic Foot & Ankle Society (AOFAS) midfoot scores, Tegner activity level scores, complications, patient-reported satisfaction, and imaging results (Meary angle in the weightbearing lateral view, talo-first metatarsal angle and talonavicular coverage angle in the weightbearing anteroposterior view) were used to describe outcomes.

RESULTS

Thirty-two eligible patients responded to the latest follow-up request and were included in this study. The mean follow-up duration was 37.1 ± 16.0 months. The average VAS pain score improved from 4.7 ± 1.8 preoperatively to 0.9 ± 1.2 at the latest follow-up (P<.001). The average AOFAS midfoot score improved from 67.1 ± 8.5 preoperatively to 90.2 ± 10.7 at the latest follow-up (P<.001). The preoperative and postoperative Tegner activity level scores were similar (3.3 ± 1.5 vs 3.5 ± 1.6, P=.136). The overall complication rate was 37.5%. The most common complication was nonunion (31.3%). The overall satisfaction rate was 90.6%. Similar outcomes were observed between the flatfoot and the nonflatfoot subgroups.

CONCLUSION

Fusion for painful type II accessory naviculars resulted in good symptom relief, function improvement, and patient satisfaction at midterm follow-up, but the nonunion rate was relatively high. Fusion for painful type II accessory naviculars with or without asymptomatic mild to moderate flatfoot brought about similar clinical outcomes.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

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.

Injuries to the Spring Ligament: Nonoperative Treatment

The fibrocartilage within the superomedial calcaneonavicular (spring) ligament is part of an interwoven complex of ligaments that span the ankle, subtalar, and talonavicular joints. Acute isolated rupture of the spring ligament has been reported in association with an eversion ankle sprain. Attenuation and failure of the spring ligament causes complex 3D changes called the progressive collapsing foot deformity (PCFD). This deformity is characterized by hindfoot eversion, forefoot supination, collapse of the medial longitudinal arch, and forefoot abduction. Nonoperative treatment of an isolated spring ligament rupture and PCFD using various designs of orthoses have shown promising results.

The Spring Ligament Complex-Anatomy and Function

This article provides an overview of the soft tissue contributions to the normal structures that surround the talo-calcaneal-navicular (TCN) joint of the human arch. The TCN joint has a multiplanar range of motion that makes it essential to the kinetic coupling that links the forefoot and hindfoot. The soft tissue connection surrounding this joint is known as the spring ligament complex. More accurate knowledge of the anatomy of this complex will enhance the understanding of its role in the support of the head of the talus and, potentially, its critical interactions with the normal or abnormal function of the arch.

Current Concepts in Treatment of Ligament Incompetence in the Acquired Flatfoot

Flatfoot deformity consists of a loss of medial arch, hindfoot valgus, and forefoot abduction. Historically considered a posterior tendon insufficiency, multiple ligament damage and subsequent incompetence explain the different clinical presentations with varying degrees of deformity. When surgery is deemed necessary, depending on the apex of the deformity, skeletal and soft tissue procedures are considered to keep motion and restore function. Osteotomies are considered at every level where an apex of deformity is found. The recently designated tibiocalcaneonavicular ligament comprises the older superficial and deep deltoid and spring ligaments; its repair or reconstruction should be considered in most flatfoot cases.

Clinical Appearance of Medial Ankle Instability

Whereas tenderness, ecchymosis, and swelling over the deltoid ligament have relatively poor sensitivity, resulting valgus and pronation deformity that is seen to disappear when the patient is asked to activate the posterior tibial muscle or to go in tiptoe position is the hallmark for the presence of medial ankle instability. A pain on palpation at anteromedial edge of the ankle confirms the diagnosis. Various stress tests permit to confirm and specify the injury pattern. A pseudo hallux rigidus is the consequence of a hyperactivity of flexor hallucis longus muscle to protect the foot against the valgus and pronation deformity.