Short Plantar Ligaments Research Articles

Anatomical analysis of ligaments surrounding calcaneocuboid joint; implications for role in foot stability.

The calcaneocuboid joint is located in the lateral part of the foot and acts as a major stabilizer for the foot. Injuries to this joint often occur in association with ankle or foot injuries and are frequently overlooked, subsequently causing chronic pain or osteoarthritis. However, the relationship between ligaments surrounding the joint and joint instability remains unclear. Therefore, this study aimed to clarify the morphology and position of the ligaments surrounding the calcaneocuboid joint, and to reveal the relationship between the ligament structure. The position and morphology of the bifurcate ligament (subdivided into calcaneonavicular and calcaneocuboid ligaments), dorsal calcaneocuboid ligament, lateral calcaneocuboid ligament, long plantar ligament, and short plantar ligament were measured (N = 11 feet in 6 Japanese cadavers). The circumference of the joint was quartered, while the ligament-uncovered area and the estimated cross-sectional area of each ligament were compared between the four sides. Furthermore, the estimated cross-sectional area of each ligament was calculated as an index for the ligament strength. The inferolateral side of the calcaneocuboid joint had the most uncovered area (54.63%) by the ligaments. In addition, the cross-sectional area of the ligaments on the lateral side was considerably smaller than that on the medial side. Our results suggest that ligament weakness on the inferolateral side may cause instability of the calcaneocuboid joint, especially after an inversion sprain injury, and may decrease the lateral longitudinal arch function, which results in chronic foot pain.

How Does Lateral Column Lengthening Correct the Flatfoot? A Cadaveric Study

Category: Hindfoot; Basic Sciences/Biologics Introduction/Purpose: Since its description by Evan for correction of overcorrected clubfoot cases, lateral column lengthening ( LCL) has been widely used for correction of pes planovalgus deformity of any etiolog. The main indication is correction of forefoot abduction manifested radiologically as talonavicular uncoverage. It was reported by many authors that LCL improved forefoot abduction and talonavicular uncoverage, but it was also noticed that LCL corrects the flattening of medial longitudinal arch. The mechanism by which LCL corrects the medial longitudinal arch is still not clearly understood. It was also reported that LCL is associated with forefoot supination, but the exact mechanism of supination is not understood. This study aimed to try to understand the mechanism by which LCL changes the shape of the foot. Methods: LCL osteotomy using Hintermann technique was performed in ten fresh frozen below knee cadaveric specimens. After completion of the osteotomy, the talus and leg were removed to monitor how the foot moves under the talus with opening of the osteotomy to change the shape of the foot. The amounts of osteotomy displacement medially, laterally and planetary were observed and measured. After that, the whole plantar skin was removed and plantar ligaments were dissected to study the influence of plantar ligaments on the plane of motion of the osteotomy and the effect of the osteotomy on plantar ligaments. Results: With opening of the osteotomy, the distal portion did not move in pure adduction. Instead, it moved medial and plantar, working as a dorsolateral opening wedge . So, the distal portion was adducted and plantarflexed correcting the forefoot abduction and the flat arch. Because the osteotomy opens dorsally and laterally only, the lateral part of the distal portion was plantar flexed more than the medial part, and this is the cause of forefoot supination. After dissection of plantar ligaments, it was found that the long and short plantar ligaments prevent the osteotomy from opening inferiorly . It was possible to move the distal portion in pure adduction only after cutting the long and short plantar ligaments. Plantar fascia was relaxed after opening of the osteotomy. Conclusion: This mayexplain how the LCL osteotomy corrects the flat medial longitudinal arch and how it causes supination and lateral side overload. Based on this study, Cotton osteotomy should be added to LCL to correct the supination. Also, plantar fascia tightening can not be the cause of medial longitudinal arch correction as it actually becomes more lax after opening of the osteotomy.

The Impact of Tendon Lengthening Following Achilles Tendon Repair on Foot Kinetics, a Finite Element Analysis

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Triceps surae muscle force is transferred through the Achilles tendon to the calcaneus and from the calcaneus to the plantar fascia and then to the metatarsal heads and the toes which exert force on the ground. Achilles tendon ruptures occur in tendons that have reached a critical point of intrasubstance degeneration. The Achilles tendon almost always heals but frequently lengthens during the healing process, leading to an alteration in the triceps surae force production profile. We hypothesized that Achilles tendon overlengthening has implications not only for force generation but likely has many other impacts throughout the foot. The goal of this work was to evaluate the effect of a lengthened Achilles tendon following tendon repair on the kinetics of the foot. Methods: A validated finite element model of the foot was used to compare foot biomechanics between the foot with a functional and non-functional Achilles tendon. The model of the foot constructed from CT scan images of a female cadaveric foot weighing 60 kg included all 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The model was loaded with 0.5 body weight applied at the center of mass and 0.25 body weight applied to the Achilles tendon simulating quiet stance. The tendon forces were applied using force vectors in the direction of their lines of action. The foot with a non-functional Achilles tendon was created by unloading the Achilles tendon since triceps surae muscle shortening due to tendon lengthening significantly decreases force production. The force transmitted through the joints, force in the ligaments, and plantar pressure were determined for both the foot with a functional and non-functional Achilles tendon. Results: We found that the force transmitted through all the joints decreased when the Achilles tendon force was removed (Figure 1a). In addition, removing the Achilles tendon decreased the force within the plantar fascia, long and short plantar ligaments, and deep deltoid ligament, while it increased the force within the spring and superficial deltoid ligaments (Figure 1b). The plantar fascia experienced the greatest reduction in ligament force after unloading of the Achilles tendon (from 93 N to 26 N). Moreover, the maximum plantar pressure in the heel fat pad increased from 164 kPa to 231 kPa when the Achilles tendon was removed. Conclusion: The varying changes in the force in the ligaments and joints due to Achilles lengthening suggest that Achilles tendon rupture with sequent healing with overlengthening can alter the force distribution throughout the entire foot. A major implication of this work is that in treating Achilles ruptures, an extended period of protection with heel wedges beyond the customary six weeks may be needed to prevent over lengthening of the Achilles. Moreover, this study supports the efficiency of surgical lengthening of the Achilles in the treatment of diabetic forefoot foot ulcers by shifting the plantar pressure towards the calcaneus.

The Role of the Plantar Fascia in Supporting the Arch in Flatfoot Deformity

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: The osseous structure of the foot has been described as an arch-like triangular structure or truss where the plantar fascia (PF) functions as the tensile element, maintaining the overall length of the arch. The importance of the PF in maintaining the arch has likely been underestimated because only minor abnormalities in its structure are seen on MRI studies in patients with flatfoot deformity. However, the importance of a ligament in preventing deformity may not be correlated with its attenuation seen on MRI. We hypothesized that the degenerative elongation of the plantar fascia would be a necessary precursor of arch collapse. The goal of this study was to evaluate the role of the plantar fascia in arch stability in flatfoot deformity. Methods: We used a validated finite element model of the foot reconstructed from CT scan of a female cadaveric foot weighing 60 kg. The model included 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The flatfoot model was created by simulated transection of the ligaments and unloading of the posterior tibial tendon. The model was used to assess the impact of isolated PF failure on the development of flatfoot deformity, evaluate the capability of the PF when reconstructed to restore foot alignment, and determine the amount of progressive strain that constitutes failure for each ligament. Foot alignment angles were used to evaluate the foot alignment. For comparison, the angles were also evaluated for other ligament tears. The impact of PF failure on force changes in the remaining ligaments was also investigated by quantifying ligament force changes during simulated PF cutting in the foot model. Results: When compared to the intact and flatfoot models, we found that the individual release of the PF cannot cause deformity (Figure 1). However, it significantly increased the force in the long (142%) and short plantar (156%), deltoid (45%), and spring ligaments (60%), potentially putting the foot at risk of arch instability over time. Moreover, we found that the PF was the structure most able to restore the arch (Figure 1a). The PF was also found to play a secondary role in reducing hindfoot valgus and forefoot abduction deformities (Figures 1b,1c). Moreover, to produce deformity, a considerable amount of attenuation in the spring (strain= 41%) and interosseous talocalcaneal ligament (strain= 27%), but only a small amount in the plantar fascia (strain= 10%) was needed. Conclusion: In comparing normal to flatfoot models of the foot, we found that isolated PF release did not cause arch collapse, but that arch collapse could not occur without elongation of the PF. While the progressive strain in the PF needed to enable arch collapse was small, the PF is a very long ligament, thus even small strain within the PF corresponds to substantial change in overall length of the arch. Chronic degeneration of the PF leading to plantar fasciitis may be an early sign of impending flatfoot deformity.

Comparison of different surgical treatments for stage II progressive collapsing foot deformity: a finite element analysis

BackgroundThis study analyzed the advantages and disadvantages of different procedures for stage IIA progressive collapsing foot deformity (PCFD) through three-dimensional finite element models.MethodsA previous validated stage IIA PCFD FEA model was established consisting of 16 bones, 56 ligaments, 5 muscles and soft tissues. The ligament properties of the spring, deltoid, short plantar and long plantar ligaments, and plantar fascia were attenuated according to a previous publication. Medial column fusion (MCF), medializing calcaneal osteotomy (MCO), lateral column lengthening (LCL), and subtalar joint arthroereisis (SJA) operations were simulated in this model. The indexes of plantar stress distribution, maximum von Mises of the medial and lateral columns, strain of the medial ligaments and plantar fascia that supported the medial longitudinal arch, arch height, talo-first metatarsal angle, calcaneus pitch angle, and talonavicular coverage angle were all compared before and after simulated single-foot weight loading.ResultsThe maximum plantar stress of PCFD decreased with MCO and SJA but increased with MCF and LCL. MCF and LCL failed to significantly reduce the stress on the medial column fragments, thereby increasing their stress. Both MCO and SJA relieved medial plantar stress. MCF had no significant effect on stress relief of the medial ligament. MCO, LCL, and SJA were all shown to reduce the pressure on the medial plantar ligament, with LCL having the most obvious effect. All four procedures corrected the arch deformity; however, MCF was not as effective as the other methods. SJA is the best method for restoring arch height and correcting arch deformities. For stage IIA PCFD, isolated MCF failed to reduce pressure on the medial column; however, isolated MCO significantly reduced the pressure on the medial plantar and ligamentous soft tissues while restoring the foot’s arch and correcting the hindfoot valgus.ConclusionSJA with type II sinus tarsi implant effectively transferred pressure from the medial plantar tract to the lateral side and restored the arch. Isolated LCL was not found suitable for stage IIA PCFD.

How Does Lateral Column Lengthening Improve the Medial Longitudinal Arch? Now I Started to Understand!

Category: Hindfoot; Other Introduction/Purpose: Since its description by Evan for correction of overcorrected clubfoot cases, lateral column lengthening (LCL) has been widely used for correction of pes planovalgus deformity of any etiology, including flexible flat foot deformity in adolescents and adults, either as a solitary procedure or in combination with other bony or soft tissue procedures. The main indication is correction of forefoot abduction manifested radiologically as talonavicular uncoverage. Different techniques were described including Evan and Hintermann techniques. It was reported by many authors that LCL improved forefoot abduction and talonavicular uncoverage, but it was also noticed that LCL corrects the flattening of medial longitudinal arch. The mechanism by which LCL corrects the medial longitudinal arch is still not clearly understood. It was also reported that LCL is associated with forefoot supination, but the exact mechanism of supination is not understood. This study aimed to try to understand the mechanism by which LCL changes the shape of the foot. Methods: LCL osteotomy using Hintermann technique was performed in ten fresh frozen below knee cadaveric specimens. After completion of the osteotomy, the talus and leg were removed to monitor how the foot moves under the talus with opening of the osteotomy to change the shape of the foot. After that, the whole plantar skin was removed and plantar ligaments were dissected to study the influence of plantar ligaments on the plane of motion of the osteotomy and the effect of the osteotomy on plantar ligaments. Results: With opening of the osteotomy, the distal portion of the foot did not move in pure adduction as might be expected. Instead, it moved medial and plantar, and the osteotomy worked as a dorsolateral opening wedge osteotomy meaning that the osteotomy opened laterally but not medially, and dorsally but not inferiorly. The result was that the distal portion was adducted and plantar flexed, so it can correct the forefoot abduction and the flat arch. Because the osteotomy opens dorsally and laterally only, with no opening medially or inferiorly, the lateral part of the distal portion was plantar flexed more than the medial part, and this is the cause of forefoot supination. After dissection of the plantar ligaments to understand their influence on the osteotomy, it was found that the long and short plantar ligaments prevent the osteotomy from opening inferiorly and force it to work as a dorsolateral opening wedge. It was possible to move the distal portion in pure adduction only after cutting the long and short plantar ligaments. As the osteotomy worked as a dorsolateral opening wedge, the plantar fascia which is plantar and medial was relaxed after opening of the osteotomy. Conclusion: May be this can explain how the LCL osteotomy corrects the flat medial longitudinal arch and how it causes supination and lateral side overload. Based on this study, Cotton osteotomy may be needed to be added to LCL to correct the supination. Also, plantar fascia tightening cannot be the cause of medial longitudinal arch correction as it actually becomes more lax after opening of the osteotomy

Computational Modeling of Peritalar Joint Contact Mechanics in Flexible Flatfoot Deformity

Category: Hindfoot; Ankle; Ankle Arthritis Introduction/Purpose: Patients with longstanding progressive collapsing foot deformity (PCFD) often develop osteoarthritis of the peritalar (tibiotalar, subtalar, and talonavicular) joints, which can be symptomatic or can lead to fixed deformities that further complicate the treatment of other sequalae of the deformity (Mann, 1992). Degeneration and subsequent tearing of the arch supporting ligaments leads to altered joint contact mechanics which is a likely causative factor in the development of arthrosis (Hauser and Dolan, 2011). However, the initial effect of ligament tears on changes in joint contact mechanics in the collapsing foot has not been well characterized. The goal of this work was to compare the joint contact mechanics between the neutrally aligned and the flexible flatfoot (collapsed foot). Methods: A validated finite element model of the foot (Malakoutikhah et al., 2022a) was used to compare joint contact pressures between the normally aligned and the collapsed foot. The model of the foot constructed from CT scan images of a female cadaveric foot weighing 60 kg included all 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The model was loaded with 0.5 body weight applied at the center of mass and 0.25 body weight applied to the Achilles tendon simulating quiet stance. The collapsed foot model was created by simulated transection of the plantar fascia, long plantar, short plantar, deltoid, and spring ligaments and unloading of the posterior tibial tendon (Malakoutikhah et al., 2022b). The joint contact pressure maps were determined for both the neutrally aligned and collapsed foot models. The average and peak contact pressures were compared. Results: The peak contact pressures were increased in the tibiotalar and subtalar joints, but paradoxically were decreased in the talonavicular joint in the collapsed as compared to the neutrally aligned foot (Figure 1). The center of pressure was markedly different in all three joints between the neutral and collapsed foot conditions. Specifically, collapsing the foot caused two centers of the talonavicular joint peak pressure to shift towards the central region of the navicular bone, which were evenly distributed in the lateral and medial regions in the neutrally aligned foot. In the subtalar joint, the peak pressure that was uniformly distributed in the lateral and medial regions of the posterior facet in the neutrally aligned foot shifted towards the lateral region in the collapsed foot. Similarly, the peak contact pressure across the tibiotalar joint moved from the center to the lateral region when the foot collapsed. Conclusion: Degenerative tearing of the arch supporting ligaments in PCFD leads to an increase and laterization of the contact pressure in the tibiotalar and subtalar joints with a decrease of the pressure in the talonavicular joint. The paradoxical unloading of the talonavicular joint may be a result of the inability of the malaligned medial column to transmit force from the hindfoot to the forefoot. One implication of this work is that future treatments of PCFD might be directed towards normalizing contact pressure within the peritalar joints to prevent the progression of disease and the development of arthrosis.

A computational model of force within the ligaments and tendons in progressive collapsing foot deformity.

Progressive collapsing foot deformity results from degeneration of the ligaments and posterior tibial tendon (PTT). Our understanding of the relationship between their failures remains incomplete. We sought to improve this understanding through computational modeling of the forces in these soft tissues. The impact of PTT and ligament failures on force changes in the remaining ligaments was investigated by quantifying ligament force changes during simulated ligament and tendon cutting in a validated finite element model of the foot. The ability of the PTT to restore foot alignment was also evaluated by increasing the PTT force in a foot with attenuated ligaments and comparing the alignment angles to the intact foot. We found that failure of any one of the ligaments led to overloading the remaining ligaments, except for the plantar naviculocuneiform, first plantar tarsometatarsal, and spring ligaments, where removing one led to unloading the other two. The combined attenuation of the plantar fascia, long plantar, short plantar, and spring ligaments significantly overloaded the deltoid and talocalcaneal ligaments. Isolated PTT rupture had no effect on foot alignment but did increase the force in the deltoid and spring ligaments. Moreover, increasing the force within the PTT to 30% of body weight was effective at restoring foot alignment during quiet stance, primarily through reducing hindfoot valgus and forefoot abduction as opposed to improving arch collapse. Our findings suggest that early intervention might be used to prevent the progression of deformity. Moreover, strengthening the PTT through therapeutic exercise might improve its ability to restore foot alignment.

The contribution of the ligaments in progressive collapsing foot deformity: A comprehensive computational study.

The contribution of each of the ligaments in preventing the arch loss, hindfoot valgus, and forefoot abduction seen in progressive collapsing foot deformity (PCFD) has not been well characterized. An improved understanding of the individual ligament contributions to the deformity would aid in selecting among available treatments, optimizing current surgical techniques, and developing new ones. In this study, we evaluated the contribution of each ligament to the maintenance of foot alignment using a finite element model of the foot reconstructed from computed tomographyscan images. The collapsed foot was modeled by simulating the failure of all the ligaments involved in PCFD. The ligaments were removed one at a time to determine the impact of each ligament on foot alignment, and then restored one at a time to simulate isolated reconstruction. Our findings show that the failure of any one ligament did not immediately lead to deformity, but that combined failure of only a few (the plantar fascia, long plantar, short plantar, deltoid, and spring ligaments) could lead to significant deformity. The plantar fascia, deltoid, and spring ligaments were primarily responsible for the prevention of arch collapse, hindfoot valgus, and forefoot abduction, respectively. Moreover, to produce deformity, a considerable amount of attenuation in the spring, tibiocalcaneal, interosseous talocalcaneal, plantar naviculocuneiform, and first plantar tarsometatarsal ligaments, but only a small amount in the plantar fascia, long plantar, and short plantar ligaments was needed. The results of this study suggest that the ability of a ligament to prevent deformity may not correlate with its attenuation in a collapsed foot.

Anomalous plantar intrinsic foot muscle attaching to the medial longitudinal arch: possible mechanism for medial nerve entrapment: a case report

BackgroundMuscular variations are potentially symptomatic and may complicate imaging interpretation. Intrinsic foot musculature and extrinsic tendon insertion variations are common. Distinct supernumerary muscles are rare. We report a novel anomalous intrinsic foot muscle on the medial longitudinal arch.Case presentationAn accessory muscle was encountered on the medial arch of the right foot of a 78-year-old white male cadaver, between layers two and three of the foot intrinsics. It did not appear to be a slip or variant of a known foot muscle. This muscle consisted of two slips that ran transversely on the plantar aspect of the medial arch, crossing the medial transverse tarsal joint and attaching to the tuberosity of the navicular, the short and long plantar ligaments, and spring ligament.ConclusionsThe medial plantar vessels and nerve passed from deep to superficial between the two slips, and this suggests a possible location for medial nerve entrapment.

Morphological characteristics of the plantar calcaneocuboid ligaments

BackgroundThe aim of this study was to clarify the differences in morphological features between the long plantar ligament (LPL) and the short plantar ligament (SPL).MethodsThis investigation examined 50 legs from 25 Japanese cadavers. The LPL and SPL of each leg were classified into one of three types based on the shape and number of fiber bundles. Then, fiber bundle length, fiber bundle width, and fiber bundle thickness were measured.ResultsThe LPL was rectangular in shape (Type I) in 12%, hourglass shape (Type II) in 62%, and triangular in shape (Type III) in 26%. The SPL was a single fiber bundle (Type I-a) in 26%, a surface fiber bundle and a deep fiber bundle (Type I-b) in 60%, and a surface fiber bundle (medial and lateral) and a deep fiber bundle (Type II) in 14%. Regarding the morphological characteristics, there were no significant differences among the types in the LPL, but there were differences between types and between surface and deep fiber bundles in the SPL.ConclusionsFor the LPL, the hourglass shape is the most common type. However, there appeared to be no functional difference due to the difference in the shape of the LPL, since there were no significant differences among the types in the LPL. For the SPL, there were types of single, double and triple fiber bundles; there may be functional differences based on the number of fiber bundles and between superficial and deep fibers.

Anatomical Study of the Cuboid and Its Ligamentous Attachments and Its Implications for a Cuboid Osteotomy.

Background:Lateral column lengthening (LCL) for flexible flatfoot is an effective surgery with powerful correction of deformity because it tightens only the lateral third of the long plantar ligament (LPL). However, LCL has been associated with joint damage at the osteotomy site and loss of foot flexibility owing to joint fixation. We focused on the cuboid and investigate a novel anatomical LCL osteotomy site that effectively tightens the LPL without damaging any joints.Methods:We studied 24 feet of 12 cadavers (mean age, 80.8 years). The lengths of the LPL and short plantar ligament, locations of the attachments, and shape and location of the cuneocuboid joint on the medial side of the cuboid were studied. ImageJ software was used to measure the osteotomy angle.Results:The lateral cuboid attachment of the LPL on average was located 4.6 mm from the calcaneocuboid joint, and the cuneocuboid joint on average was located 6.7 mm from the cuboid-metatarsal joint on the medial surface of the cuboid. The direct line connecting the anterior cuneocuboid joint and the oblique crest of the cuboid on average was at a 10.3-degree inclination posterior to the cuboid-metatarsal joint.Conclusion:A straight line must be selected between a point 4 mm from the calcaneocuboid joint laterally and 6 mm from the cuboid-metatarsal joint medially at a 10-degree posterior tilt to the cuboid-metatarsal joint to perform a cuboid osteotomy LCL without damaging the articular surface.Clinical Relevance:We investigated a potential novel cuboid osteotomy method for LCL.

Analysis of the main passive soft tissues associated with adult acquired flatfoot deformity development: A computational modeling approach

Adult acquired flatfoot deformity (AAFD) is a pathology with a wide range of treatment options. Physicians decide the best treatment based on their experience, so the process is entirely subjective. A better understanding of soft tissue stress and its contribution in supporting the plantar arch could help to guide the clinical decision. Traditional experimental trials cannot consistently evaluate the contribution of each tissue. Therefore, in this research a 3-Dimensional FE foot model was reconstructed from a normal patient in order to measure the stress of the passive stabilizers of the arch, and its variation in different scenarios related with intermediate stages of AAFD development. All bones, the plantar fascia (PF), cartilages, plantar ligaments and the spring ligament (SL) were included, respecting their anatomical distribution and biomechanical characteristics. An AAFD evaluation scenario was simulated. The relative contribution of each tissue was obtained comparing each result with a normal case. The results show that PF is the main tissue that prevents the arch elongation, while SL mainly reduces the foot pronation. Long and short plantar ligaments play a secondary role in this process. The stress increment on both PF and SL when one of two fails suggests that these tissues complement each other. These findings support the theory that regards the tibialis posterior tendon as a secondary actor in the arch maintenance, compared with the PF and the SL, because this tendon is overstretched by the hindfoot pronation around the talonavicular joint. This approach could help to improve the understanding of AAFD.

MRI evaluation of ligaments and tendons of foot arch in talar dome osteochondral lesions.

Background There are no publications in literature describing an association between disorders of the ligaments and tendons supporting the foot arch and osteochondral lesions of the talus (OCLT). We believe there may be a correlation between the damage of these structures. Purpose To investigate the pathologies of main ligaments and tendons that support the foot arch in sprained ankles, by reviewing magnetic resonance imaging (MRI) studies and comparing the results in two groups of patients, with and without OCLT. Material and Methods MR images from 316 patients examined in the orthopedic clinic for ankle sprain were evaluated for pathologic findings of the plantar fascia, short and long plantar ligaments, spring ligament, sinus tarsi, and ankle tendons supporting the foot arch. Findings were compared between two groups of patients: 158 patients with OCLT and 158 patients without OCLT. Results Plantar fascia, short plantar ligament, and spring ligament abnormalities were seen in 50 (31.6%), 28 (17.7%), and 60 (38%) patients with OCLT, and in nine (5.6%), three (1.9%), and 18 (11.4%) patients without OCLT, respectively ( P < 0.05). Sinus tarsi and tendon abnormalities were seen in 11 (6.7%) and nine (5.7%) patients with OCLT, and in eight (5%) and eight (5%) patients without OCLT, respectively ( P > 0.05). Two or more associated abnormalities were present in 50 (31.6%) patients with OCLT and in 11 (6.7%) without OCLT ( P < 0.05). Conclusion Plantar fascia, short plantar ligament, and spring ligament abnormalities were commonly seen in patients with OCLT on MRI, while sinus tarsi and tendon abnormalities were not. Concomitant pathologies have an increased incidence in patients with OCLT.

Ligament Balancing for Total Ankle Arthroplasty: An in vitro Evaluation of the Elongation of the Hind- and Midfoot Ligaments

The changes in length of the hindfoot ligaments in response to alterations in ankle and subtalar joint orientation under physiologic load in eight fresh-frozen cadaver limbs were documented. In eversion, the tibiocalcaneal (11% ± 4%, mean ± SD], calcaneofibular (6% ± 4%), posterior talofibular (7% ± 4%), posterolateral talocalcaneal (21% ± 9%), posteromedial talocalcaneal (33% ± 45%) and calcaneonavicular (bifurcate) (8% ± 7%) ligaments were elongated relative to their lengths in inversion. In inversion, the anterior capsular (talocalcaneal) (5% ± 3%) and the plantar cuboidnavicular (5% ± 6%) ligaments were elongated relative to their everted lengths. In dorsiflexion, the superficial (26% ± 8%) and deep posterior tibiotalar (30% ± 13%), calcaneofibular (8% ± 4%), tibiocalcaneal (4% ± 2%) and lateral talocalcaneal (cervical) (2% ± 1%) ligaments were elongated. In plantarflexion, the tibionavicular (26% ± 5%) and the anterior talofibular (7% ± 4%) ligaments were lengthened. No statistically significant elongation was documented in any ankle position for the anterior tibiotalar, talocalcaneal interosseous, plantar calcaneocuboid, calcaneocuboid (bifurcate), all components of the spring ligament, and the dorsal cuboidnavicular ligaments. Components of the deltoid ligament complex elongated largest at the ankle joint with any hindfoot movement but inversion. Therefore, selective release of components of the deltoid ligament complex may provide a means for achieving optimal ligament balancing in total ankle arthroplasty. Specifically, release of the superficial and deep posterior tibiotalar ligament may improve range of motion in total ankle arthroplasties, whereas the release of the tibiocalcaneal ligament may correct a varus talar tilt.

Mechanical behaviors of the foot after individual releases of plantar fascia and ligaments during the balanced standing

To quantify mechanical effects of plantar fascia and ligaments on the arch structure, a 3D finite element model of the foot was created to simulate the balanced standing posture. Four cases after individual releases of plantar fascia, spring ligament, long and short plantar ligaments were simulated respectively to compare their consequences to the predictions of the intact structure. It was founded that the foot arch didn’t collapse obviously after any individual release of these structures. As plantar fascia was released, tensions of plantar ligaments were largely increased. Long and short plantar ligaments performed mutual compensation functions.

Relative contributions of plantar fascia and ligaments on the arch static stability: a finite element study

The plantar fascia (PF) and major ligaments play important roles in keeping the static foot arch structure. Their functions and relative contributions to the arch stability have not been well studied. A three-dimensional finite element foot model was created based on the reconstruction of magnetic resonance images. During balanced standing, four cases after individual releases of the PF, spring ligament (SL), and long and short plantar ligaments (LPL and SPL) were simulated, to compare their biomechanical consequences with the normal predictions under the intact structure. Although the predictions showed the arch did not collapse obviously after each structure sectioning, the internal mechanical behaviors changed considerably. The PF release resulted in the maximal increases of approximately 91%, 65% and 47% in the tensions of the LPF, SPL and SL, produced the largest changes in all bone rotations, and brought an obvious shift of high stress from the medial metatarsals to the lateral metatarsals. The SL release mainly enhanced bone rotation angles and weakened the joint stability of the arch structure. The LPL and the SPL performed the roles of mutual compensation as either one was released. The influence of the LPL on the load distribution among metatarsals was greater than for the SPL and the SL.

Effect of injury to plantar ligaments on plantar pressure distribution

Objective To explore the changes in plantar pressure distribution and contact area after injury to the plantar ligaments in a normal adult cadaveric model. Methods Seven fresh adult cadaverie feet were used in the test. F-scan insoles were put under the plantar aspect of the feet when the specimens were loaded to 700 N vertieally. The plantar pressure data in the specimens were collected and stored before and after the plantar fascia, spring ligament, short plantar ligament and long plantar ligament were sectioned. Results were statistically analyzed. Results The peak pressure was always observed at the hindfoot area in all conditions. The peak plantar pressure on the forefoot was observed at the third metatarsal area and in-creased when the plantar ligaments were sectioned, while the total contact area of the foot was constant in both intact and pathological situations. Conclusion After the plantar ligaments are injured, the plantar pressure of the foot changes significantly and the pressure concentration occurs at the lateral foot, which may lead to clinical symptoms. Key words: Foot injury; Ligaments; Plantar pressure; Biomechanies

Posterior Tibial Tendon Insufficiency: Which Ligaments are Involved?

The pathology manifested in posterior tibial tendon insufficiency (PTTI) is not limited to the posterior tibial tendon. The association of ligament failure with deformity has been discussed in numerous publications, but extensive documentation of the structures involved has not been performed. The purpose of this observational study was to identify the pattern of ligament involvement using standardized, high-resolution magnetic resonance imaging (MRI) in a series of 31 consecutive patients diagnosed with PTTI compared to an age matched control group without PTTI. The structures evaluated by MRI were the posterior tibial tendon, superomedial and inferomedial components of the spring ligament complex, talocalcaneal interosseous ligament, long and short plantar ligaments, plantar fascia, deltoid ligament, plantar naviculocuneiform ligament, and tarsometatarsal ligaments. Structural derangement was graded on a five-part scale (0 to IV) with level 0 being normal and level IV indicating a tear of more than 50% of the cross-sectional area of the ligament. Standard flatfoot measurements taken from preoperative plain standing radiographs were correlated with the MRI grading system. Statistically significant differences in frequency of pathology in the PTTI group and controls were found for the superomedial calcaneonavicular ligament (p < 0.0001), inferomedial calcaneonavicular ligament (p < 0.0001), interosseous ligament (p = 0.0009), anterior component of the superficial deltoid (p < 0.0001), plantar metatarsal ligaments (p = 0.0002) and plantar naviculocuneiform ligament (p = 0.0006). The ligaments with the most severe involvement were the spring ligament complex (superomedial and inferomedial calcaneonavicular ligaments) and the talocalcaneal interosseous ligament. Ligament involvement is extensive in PTTI, and the spring ligament complex is the most frequently affected. Because ligament pathology in PTTI is nearly as common as posterior tibial tendinopathy, treatment should seek to protect or prevent progressive failure of these ligaments.

Effects of plantar fascia stiffness on the biomechanical responses of the ankle–foot complex

Background. The plantar fascia is one of the major stabilizing structures of the longitudinal arch of human foot, especially during midstance of the gait cycle. Knowledge of its functional biomechanics is important for establishing the biomechanical rationale behind different rehabilitation, orthotic and surgical treatment of plantar fasciitis. This study aims at quantifying the biomechanical responses of the ankle–foot complex with different plantar fascia stiffness. Methods. A geometrical detailed three-dimensional finite element model of the human foot and ankle, incorporating geometric and contact nonlinearities was constructed by 3D reconstruction of MR images. A sensitivity study was conducted to evaluate the effects of varying elastic modulus (0–700 MPa) of the plantar fascia on the stress/strain distribution of the bony, ligamentous and encapsulated soft tissue structures. Findings. The results showed that decreasing the Young's modulus of plantar fascia would increase the strains of the long and short plantar and spring ligaments significantly. With zero fascia Young's modulus to simulate the plantar fascia release, there was a shift in peak von Mises stresses from the third to the second metatarsal bones and increased stresses at the plantar ligament attachment area of the cuboid bone. Decrease in arch height and midfoot pronation were predicted but did not lead to the total collapse of foot arch. Interpretation. Surgical dissection of the plantar fascia may induce excessive strains or stresses in the ligamentous and bony structures. Surgical release of plantar fascia should be well-planned to minimise the effect on its structural integrity to reduce the risk of developing arch instability and subsequent painful foot syndrome.